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i
of the
•Clnivergtti? of Mi0con0in
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Vacuum Cleaning Systems
A Treatise on the Principles and
Practice of Mechanical Gleaning
BY
M. S. COOLEY, M. E.
Mechanical Engineer in Office of the Supervising
Architect, Treasury Department, Washington, D. C.
FIRST EDITION
New York:
Heating and Ventilating Magazine Company,
1 1 23 Broadway
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Copyright, 1913.
Hbatzno and Vbntilatino Magazine Co.
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182979
MRR 25 1914
.G77
CONTENTS.
CHAPTER I.
HiSTOBY OP Mechanical Cleaning.
PAGE
Early Attempts : 3
Limitations of the Carpet Sweeper 4
Compressed Air Cleaners 5
Vacuum Produced by Compressed Air 7
Compressed Air Supplemented by Vacuum 7
Piston Pump ttie First Satisfactory Vacuum Producer. . . 9
Systems Using Vacuum Only * . . 11
Renovator with Inrush Slot 13
Steam Aspirators Used as Vacuum Producers 14
Piston Pump Used Without Separators 15
First Portable Vacuum Cleaner 15
First Use of Stationary Multi-Stage Turbine Blowers 16
Separators Emptying to Sewer by Air Pressure 18
Machines Using Root Blowers as Vacuum Producers 18
CHAPTER II.
Requirements of an Ideal Vacuum Cleaning System.
Necessity and Proper Location of Stationary Parts 24
CHAPTER HI.
The Carpet Renovator.
Four Important Parts of Vacuum Cleaning System 25
The Straight Vacuum Tool 26
Renovator with Auxiliary Slot Open to Atmosphere 27
Renovator with Two Cleaning Slots 30
Renovator with Inrush Slots on Each Side 30
on Dirty Carpets 30
iii
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iv CONTENTS
PAGE
Type A Renovator Most Efficient on Dirty Carpets 36
Tests of Carpets **ArtificiaUy'' Soiled 36
Effort Necessary to Operate Various Type of Renovators. . 51
Relative Damage to Carpets with Various Type of Reno-
vators 52
CHAPTER IV.
Other Renovators.
Different Form of Renovator Necessary to Clean Walls,
Ceilings and Similar Flat Surfaces 60
Upholstery Renovators Disastrous to Surfaces Cleaned. . . 64
Attempts to Overcome Destructive Tendency of Straight-
Slot Upholstery Renovator 64
Upholstery Renovators Most Serviceable Clothing Cleaners. 65
Special Renovators for Cleaning Stairs 66
Renovation of Furs 66
Renovation of Pillows 66
CHAPTER V.
Stems and Handles.
Use of Drawn Steel Tubing for Stems of Cleaning Tools. . 70
Drawn Aluminum Tubing for Long Stems 71
Swivel Joints Between Renovator and Stem 72
Wear on Hose Near Stem 74
Methods of Overcoming. Wear of Hose 74
Valves to Cut Off Suction 78
CHAPTER VI.
Hose.
Early Types Made of Canvas-Wound Rubber Tubing 80
Standard Weight Adopted 80
First Type Produced Especially for Use in Vacuum Clean-
ing Work 81
First Attempt to Produce Light- Weight Hose 81
Other Types 82
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CONTENTS V
PAGE
Hose Couplings 82
Hose Friction 84
Effect of Hose Friction 88
Most Economical Hose Size for Carpet and Floor Renovators 93
Conditions for Plant of Small Power 97
Limit of Length for Hose 99
CHAPTER VII.
Pipe and Fittings. »
Hose Inlets 100
Pipe Friction 107
Determination of Proper Size Pipe 107
Determination of Number of Sweepers to be Operated 113
Determination of Number of Risers to be Installed 115
Size of Risers 115
Illustration of Effect of Long Lines of Piping 120
CHAPTER VIII.
Sepabatobs.
Classification of Separators '. 127
Primary Separators 127
Secondary Separators 130
Complete Separators 134
Total Wet Separator 138
CHAPTER IX.
Vacuum Pbodtjoees.
Types of Vacuum Producers 142
Displacement Type 142
Centrifugal Type 142
Power Required to Produce Vacuum 142
Reciprocating Pumps 143
Rotary Pumps 148
Centrifugal Exhausters 156
Steam Aspirators 162
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vi CONTENTS
CHAPTER X.
Control.
PAGE
First Type of Controller 166
Second Form of Control 168
Appliances for Varying Speed of Motor-Driven Vacuum
Pump 171
CHAPTER XI.
Scrubbing Systems.
First Real Mechanical Scrubbing Device 176
Combining Scrubbing with Dry Cleaning 177
Ideal Separator for Use with a Combined Cleaning and
Scrubbing System 178
CHAPTER XII.
Selection op Cleaning Plant.
Renovators 179
Hose 182
Pipe Lines 182
Separators 182
Vacuum Producers 183
Control 183
Selection of Appliances for Four Classes of Work 184
Class 1. — Plant for Residence or Small Office or De-
partmental Building, to be Not More than
One-Sweeper Capacity.
Class 2. — ^Large Office or Departmental Building
Where Carpet Cleaning is Important and
Pipe Lines are of Reasonable Length.
Class 3. — ^Large Building or Group of Buildings
Where Carpet Cleaning is Important and
Long Lines of Piping are Necessary.
Class 4. — Large or Small Plant Where Carpet Clean-
ing is Not an Important Function of the
Cleaning System
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CONTENTS vii
CHAPTER XIII.
Tests.
Early Methods of Testing .^. . 187
Most Rational System of Testing 189
Use of Vacometer 190
Proper Orifice to be Used with Each Class of Plant 191
CHAPTER XIV.
Specifications.
Award of Contracts on Evaluation Basis 193
Determination Basis of Evaluation 193
Specification for Class 1, Plant for Residence or Small
OfSce Building of One-Sweeper Capacity 194
Specification for Class 2, Plant for Large OfSce Building
Having Pipe Lines of Moderate Length 204
Specification for Class 3, Large Installation, with Unusually
Long Pipe Lines 209
Specification for Class 4, Large or Small Plant Where
Carpet Cleaning is of Secondary Importance 215
Specification for Class 5, To Give Widest Competition 218
CHAPTER XV.
Portable Vacuum CiiEANBBS.
Power Required 228
Weig'ht of Efficient Portable Cleaners 228
Limit of Power Consumption When Attached to Lighting
System 229
Disadvantage of Having Dust Bag at Outlet of Fan 230
Portables Equipped with Mechanically-Operated Brushes. . 231
Portables Exhausting Air Inside of Building 231
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TABLES.
' PAGE
1. Cleaning Tests of Dirty Carpets 34
2. Cleaning Tests of Carpets Filled with Quicksand 38
3. Cleaning Tests Using 1 oz. of Sand per Square Yard
of Carpet 40
4. Comparison of Tests Made by Mr. Reeve and by the
Author 48
5. Effort Necessary to Operate Cleaning Tools 51
6. Vacuum Required at Hose Cock to Operate Type A
Renomtors Attached to Varying Lengths of Different-
Sized Hose 89
7. Air Quantities and Vacuum at Renovator with 1-in.
Hose and 10 in. Vacuum at Hose Cock 90
8. Air Quantities and Vacuum at Renovator with Ij^-iii-
Hose and 6 in. Vacuum at Hose Cock • 90
9. Vacuum Required at Hose Cock to Operate Type C
Renovators with Various Lengths of Three Sizes of
Hose 91
10. Air Quantities Through Floor Brush with Various Sizes
and Lengths of Hose, Operated on Same System with
Type A Renovators 92
11. Horse Power Required at Hose Cock to Operate Bare
Floor Brushes on Same System with Type A Reno-
vators 93
12. Free Air Passing Brush Type of Dare Floor Reno-
vator Operated on Same System with Type C Carpet
Renovators 94
13. Horse Power at Hose Cock with Brush Type of Bare
Floor Renovator Operated on Same System with
Type C Carpet Renovators 94
ix
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X TABLES
14. Cubic Feet of Free Air Passing the Pelt-Covered Floor
Renovator Operated on Same System with Type A
Renovators 96
15. Horse Power Required at Hose Cock to Operate Felt-
Covered Floor Renovators Operated on Same System
with Type A Renovators 96
16. Vacuum at Hose Cock with 2 in. Vacuum at Type A
Renovator 97
17. Air Quantities when Bristle Bare Floor Renovators die
Used in Conjunction with Type A Carpet Renovators
at 2 in. Mercury 98
18. Pipe Sizes Required, as Determined by Air Passing
Renovators 109
19. Friction Loss in Pipe Lines, with Carpet Renovators
in Use Exclusively 109
20. Pressure Losses from Inlet to Separator in System for
Cleaning Railroad Cars 121
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ILLUSTRATIONS.
Fig. Pagb.
1. Early Type of Mechanical Cleaning Nozzle Using Com-
pressed Air 6
2. Another Type of Compressed Air Cleaning Nozzle, Supple-
mented with Vacuum Pipe 8
3. Separators Used With Combined Compressed Air and Vacuum
Machines 9
4. Piston Type of Vacuum Pump, Mounted Tandem With Air
Compressor 9
5. Mr. Kenney's First Renovator, Vacuum Alone Being Used
as Cleaning Agent 10
6. Air Compressors Arranged for Operation as Vacuum Pumps 11
7. Separators Installed by Mr. Kenney in Frick Building 12
8. Vacuum Renovator With Inrush Slot, Introduced by the
Sanitary Devices Manufacturing Company 13
9. First Portable Vacuum Cleaner, Constructed by Dr. William
Noe, of San Francisco, in 1905 16
10. Late Type of Spencer Vacuum Cleaning Machine, Operated
by Multi-Stage Turbine Blowers 17
1 1. Type A, the Straight Vacuum Tool 26
12. Type B, with Wide Slot and Wide Bearing Surface 26
13- Type C, with Auxiliary Slot, Open to Atmosphere 28
14. Type D, with Two Cleaning Slots 28
15* Type £, with Inrush Slot on Each Side of Vacuum Slot 31
16. Type F, an Exaggerated Form of Type B 31
17. Tests of Three Renovators on Dirty Carpets 35
18. Cleaning Tests of Carpets Filled with Quicksand 39
19. Cleaning Tests Using i oz. of Sand Per Square Yard of
Carpet 41
20. Three Series of Tests with Kenney Type A Renovators 45
21. Tests by Mr. Reeve, Using Type C Renovator 46
22. Tests by Mr. Reeve, Using Type D Renovator 47
23. Tests Showing E£Eiciency of Different Types of Renovators
at Different Degrees of Vacuum 50
24. Early Type of Bare Floor Renovator 55
25. Later Type of Bare Floor Renovator 55
26. Another Type of Bare Floor Renovator 56
27. Bare Floor Renovator with Felt Cleaning Surface 57
28. Bare Floor Renovator with Unusual Form of Slot 58
29. Bare Floor Renovator with Hard Felt or Composition Rub-
ber Strips 58
xi
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xii ILLUSTRATIONS
Fig. Pack.
30. Bare Floor Renovator with Rounded Wearing Surface 59
30a. The Tuec School Tool 62
31. Round Bristle Brush for Carved or Other Relief Work 62
32. Rubber-Tipped Corner Cleaner for Use on Carved or Other
Relief Work 62
33. Early Type of Upholstery Renovator 63
34. Upholstery Renovator with Narrow Slots to Prevent Damage
to Furniture 64
35. Another Type of Upholstery Renovator with Short Slots... 65
36. Hand Brush Type of Renovator 65
37. Form of Swivel Joint Connecting Stem to Renovator 72
38. Swivel Joint Arranged to Prevent Dust Lodging Between the
Wearing Surfaces 73
39. Swivel Joint in Use 74
40. Another Use of Swivel Joint, Showing Possibilities of this
Form 75
41. Operator Cleaning Trim of Door with Swivel Joint 76
42. Swivel Joint, with Screwed Union 76
43. Swivel Joint Having Ball Bearings 76
44. Action of Ball-Bearing Swivel Joint 77
45. Illustration of Defects of Plug Cocks 78
46. Bayonet Type of Hose Coupling, Introduced by the American
Air Cleaning Company 82
47. All Rubber Hose Coupling Used by the Spencer Turbine
Cleaner Company 83
48. Chart for Determining Hose Friction 86
49. Effect of Increase of Velocity on the Friction Loss 88
50. Another Test Showing Friction Loss Due to .Velocity 89
51. Inlet Cock to Prevent Air Leakage when Not in Use loi
52. Type of Automatic Self-Closing Inlet Cock 102
53. "Smooth Bore" Pipe Coupling 103
54. Joint Made of Standard Pipe Flanges 104
55. Standard Durham Recessed Drainage Fittings Generally
Used in Vacuum Cleaning Installations 105
56. Friction Loss in Pipe Lines 106
57-60. Diagrams Showing Operation of Brush and Carpet Re-
novators Under Different Conditions no
61. Typical Floor Plan of Office Building Illustrating Number
of Sweepers Required 114
62. Plan of Layout for Office Building Showing Best Loca-
tion (at d) for Vacuum Producer 118
63. Vacuum Cleaning Layout for a Passenger Car Storage Yard 122
64. Arrangement of Piping Recommended as Best for Passenger
Car Storage Yard 123
65. Good Location for Dust Separator Where Large Areas Are
Served by One Cleaning System 125
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ILLUSTRATIONS xiii
Fig. Page.
66. Location of Separators at Centers of Groups of Risers for
Large Systems 126
67. Early Type of Primary Separator, Used by Vacuum Cleaner
Company 128
68. Primary Separator Used by the Sanitary Devices Manu-
facturing Company 128
69. Primary Separator Used by the General Compressed Air and
Vacuum Cleaning Company 129
70. Primary Separator Made by the Blaisdell Engineering Co... 129
71. Secondary Separator Used by the Vacuum Cleaner Company 131
72. Secondary Separator Used by the General Compressed Air
and Vacuum Cleaning Company 13J
73. Secondary Separator Used by the Sanitary Devices Manu-
facturing Company 132
74. Type of Dry Separator Used as Secondary Separator 134
75. Form of Complete Separator Used by the Vacuum Cleaner
Company 135
76. Complete Separator Brought Out by the Electric Renovator
Manufacturing Company 136
77. Complete Separator Made by the American Radiator Company 13^
77a. Interior Construction of Dunn Vacuum Cleaning Machine 140
78. Power Consumption and Efficiency of Air Compressor Used
as a Vacuum Pump 143
79. Modification of Reciprocating Pump Made by the Sanitary
Devices Manufacturing Company 144
80. Power Consumption and Efficiency of Modified Reciprocating
Pump 145
81 and 82. Indicator Cards for Clayton and Modified Pumps. .'. . 146
83. One of the Pumps Installed in Connection with the Vacuum
Cleaning System in the New York Post Office, the
Largest Reciprocating Pump Used for this Purpose up to
the Present 148
84. Interior Arrangement of the Garden City Rotary Pump 149
85. Power Required to Operate Garden City Type of Rotary
Pump 150
86. Arrangement of Double-Impeller Root Type Rotary Pump
for Vacuum Cleaning Work 151
87. Rotary Pump Arranged with Double-Throw Switch for Re-
versing Pump 152
88. Power Consumption and Efficiency of Root Type of Pump. . 153
89. The Rotrex Vacuum Pump, Used by the Vacuum Engineer-
ing Company 153
90. Late Type of Centrifugal Exhauster Made by the Spencer
Turbine Cleaner Company , 154
91. Power and Efficiency Curves for the Spencer Machine 155
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xiv ILLUSTRATIONS
Fia Pacb.
92. Interior Arrangement of Invincible Machine, Manufactured
by the Electric Renovator Manufacturing Company.... 156
93. Power Consumption, Vacuum and Efficiency of First Types
of Invincible Machine 157
94. Power Consumption, Vacuum and Efficiency of Invincible
Machine After Valve Was Fitted to Discharge 158
95. Four-Sweeper Invincible Plant Installed in the United States
Post Office at Los Angeles, Cal 159
96. Centrifrugal Pump with Single Impeller, Manufactured by
by The United Electric Company 161
96a. Test of Centrifugal Pump with Single Impeller 162
97. Steam Aspirator Used by the American Air Cleaning Company 163
98. Steam Consumption of Steam Aspirator 164
99. First Type of Controller Introduced by the Sanitary De-
vices Manufacturing Company, known as the "Unload-
ing Valve" 167
100. Test of Controller Connected to Suction of 8-Sweepcr Piston
Pump 168
lOi. Type of Controller for Use on Pumps Without Valves 169
102. Regulator for Motor-Driven Vacuum Pump, Manufactured
by the Cutler-Hammer Manufacturing Company 170
103. Inspirator Type Vacuum Contactor, Used to Control Pilot
Motor of Cutler-Hammer Controller 171
104. Vacometer for Use in Testing Vacuum Cleaning Systems... 190
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PREFACE.
The oontents of this work are compiled from the observations
of the author through the seven years during which he has
been engaged in the preparation of specifications for, and the
testing of, complete plants installed in the buildings under the
control of the Treasury Department.
During this time it has become necessary to alter no less than
five times the stock form of specifications for stationary vacuum
cleaning plants which were adopted by the Gk>vemment, with
the intent of obtaining the widest competition possible with
efficient and economical operation, in order to keep pace with
the variation and improvement in the apparatus manufactured.
As each new tyi)e of system has come on the market a personal
investigation at the factory, together with tests, has been made.
An exhaustive test of carpet renovators was also conducted,
using one of the Government plants. In addition the vaco-
meters recommended for use in capacity tests were carefully
calibrated, using the machine at the Department of Agriculture.
The writer wishes to acknowledge the aid received from the
various manufacturers in furnishing illustrations and data on
their machines, to Messrs. Ewing & Ewing and Prof. Sidney A.
Reeve for data on tests made by Prof. Reeve and used in de-
fending the Kenney basic patent.
In analyzing the results of his tests and observations, the
writer has endeavored to put his own conclusions into concrete
form for the use of the consulting engineer and has not entered
into the problems to be encountered in the design and manu-
facture of the various forms of apparatus.
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CHAPTER I.
History of Mechanical Cleaning.
Early Attempts. — ^Whenever machinery has been introduced
to assist or replace manual labor, the earlier attempts have been
in imitating the tools formerly used by man. As the earliest
meehanically-propellod carriages were mechanical walking ma-
chines, the earliest steamboats mechanical rowing machines,
and the earliest flying machines mechanical birds, so were the
earliest mechanical cleaners in the form of mechanical brooms.
These mechanical brooms were introduced about 1880 and
took the form of the well-known street sweeper, with a large
circular brush mounted on a four-whee'led cart and rotated by
means of gearing driven from the wheels, the propelling power
being the horses which drew the machine.
This machine at once made itself unpopular with the resi-
dents of the streets cleaned on account of its great activity in
stirring up dust, because the streets were sweptt dry. This
trouble was later overcome to a considerable extent by sprink-
ling the streets before sweeping, but only at a sacrifice in
eflSciency of cleaning, especially where such uneven surfaces
as cobble or medina stone blocks formed the surface of the
roadway. Various attachments were added to reduce this dust
nuisance, but none has apparently been successful, as we see
these machines in their original form in use today.
Almost simultaneously with the introduction of the street
sweeper came its counterpart, the carpet sweeper, with a similar
but smaller brush, enclosed in a wood and metal case, the
brush being driven by friction from the wheels supporting the
box and the power for operation being derived from the person
who pushed the machine along the floor.
This machine has not been jmodifled to any great extent dur-
ing the thirty odd years of its existence. It is today in prac-
3
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4 « VACUUIM CLEANING SYSTEMS
tically its original form, and is doing no better work than when
first introduced. This form of mechanical cleaner occupied the
field of household cleaning for nearly twenty years without a
rival, during which time it won its way into the hearts and
hands of many housekeepers in this and other countries.
Limitations of the Carpet Sweeper. — This device, with its
light brush and equally light pressure on the surface cleaned
and its limited capacity for carrying the material picked up,
has never been a thorough cleaner in any sense of the word,
and has been and is now used only to take up that portion of
the usual litter and light dust which is located directly on the
surface, and is, therefore, most annoying to the housekeeper,
owing to its being visible to the eye. Because of its generous
proportions, made necessary to accommodate the material
picked up, and its centrally-pivoted handle, made necessary
by its mechanical construction, it is impossible to operate it
under low furniture. Like the lawn mower, it must be in
motion in order to opei^e its revolving brush, on which its
cleaning action is dependent. It is impossible to make use of
same in comers, along walls, or close to heavy furniture, its
use being limited to a literal slicking up of those portions of
the carpet in the most conspicuous portions of the apartment.
In spite of these serious defects it came into, and is still in,
nearly universal use, even in households equipped with the
latest approved types of mechanical cleaners. Its use on bare
floors has never been even a moderate success and in no case
has it superseded the broom and dust pan of our grandmothers
Compressed Air Cleaners. — Compressed air has been in use
for many years in foundries and machine shops, for cleaning
castings and producing certain finishes on metal. With the
introduction of modem electrical machinery it was rapidly
adapted to the cleaning of windings and other inaccessible parts
of this machinery. Its first use in cleaning buildings was un-
doubtedly in the form of an open jet for dislodging dust from
carvings and relief work, for which purpose it is very efficient
as a remover of the dust from the parts to be cleaned and also
as a distributor of this same dust over the widest possible area
for subsequent removal by other means. It has a draw-back
in that the expansion of air both cools the same and reduces
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HISTORY OF MECHANICAL CLEANING 5
its ability to retain moisture, resulting in the deposit of mois-
ture on the surfaces cleaned.
About 1898, attempts to overcome the objections to the open
air jet and to produce a commercially successful compressed
air carpet cleaner were undertaken almost simultaneously by
two companies, the American Air Cleaning Company, of Mil-
waukee, operating under the Christensen patents, and the
General Compressed Air Cleaning Company, of St. Louis, (^cr-
ating under the Thurman patents.
The renovator used by the American Air Cleaning Com-
pany consisted of a heavy metal frame, about 18 in. long and
12 in. wide, having mounted on its longer axis a wedge-like
nozzle extending the entire length of the frame, with a very
narrow slit, 1/64 in. wide, extending the entire length of its
lower edge. This nozzle was pivoted and so connected to the
operating handle, by which the renovator was moved over the
floor, that when the renovator was alternately pushed and
pulled over the surface to be cleaned, the slot was always
inclined in the direction in which the renovator was being
moved. The top of the renovator was closed by a canvas bag,
smaller at the neck than in its center, which was supported by
a wire hook.
Air was introduced into the nozzle, at a pressure of from
45 to 55 lbs. per square inch, and issued from the slot in a thin
sheet which impinged on the carpet at an angle. The frame
was held close to the carpet by its weight, preventing the
escape of the air under its lower edge. The air striking the
carpet at an angle was deflected up into the bag, inflating
same like a miniature balloon. The dust loosened from the
carpet by the impact of the air was carried up into the bag
where it lodged, the air escaping through the fabric of the
canvas into the apartment.
The renovator used by the General Compressed Air Clean-
ing Company differed from the above-described renovator in
that it contained two noz^s, with slots inclined. at fixed angles
to the carpet. A pair of hand-operated valves were provided
in the handle to introduce air into the nozzle which was inclined
in the direction in which the renovator was moving; other-
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6 VACUUM CLEANING SYSTEMS
wise the renovator was identical with that used by the Mil-
waukee company.
These renovators were generally supplied with air from a
portable unit, consisting of an air compressor, driven by a gaso-
line engine mounted with the necessary gasoline and air storage
tanks on a small truck. One of these maohines was in use in
Washington last year, but its use at that time was very limited
and it is not to be seen this year.
These trucks were drawn up in front of the building to be
cleaned and a large-size hose, usually 1J4 ^- in diameter, was
carried into the house and attached to an auxiliary tank from
which 54 -in. diameter hose lines were carried to two or more
renovators.
A few buildings were equipped with air compressors and
pipe lines, with outlets throughout the building for use with
this type of renovator, among which was the Hotel Astor in
New York City.
These renovators, the construction of which is shown diagram-
matically in Fig. 1, required approximately 35 cu. ft. of free
PIG. I. EARLY TYPE OP MECHANICAL CLEANING NOZZLE
USING COMPRESSED AIR.
air per minute at a pressure of from 45 to 55 lbs. per square
inch and were usually driven by a 15 H. P. e^gine.
The renovators were very heavy to carry about, although
their operation with the air pressure under them was not
difficult. However, their operation was complicated, requiring
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HISTORY OF MECHANICAL CLEANING 7
skUled operators. Owing to their generous proportions it was
impossible to clean around furniture, making its removal from
the apartment necessary, and limiting their use to the cleaning
of earpeits at the time of general house cleaning. The cooling
effect of the expansion of the air in the nozzle often caused
condensation of moisture on the carpets when the relative
humidity was hig»h. They were also at a disadvantage in that
all the heavy dust collected in the canvas bag had to be carried
from the apartment by hand. Owing to the constant agitation
of the dust in the bag by the entering air currents, much of
the finer particles of dust and all the disease germs liberated
by the renovator were blown through the bag back into the
apartment. They were not, therefore, by any means sanitary
devices.
Vacuum Produced by Compressed Air. — The General Com-
pressed Air Cleaning Company also introduced another form of
renovator for use with their compressed air plants. This was
composed of an ejector operated by compressed air, with a
short hose attached to a carpet renovator of the straight nar-
row-slot type, such as was used later in vacuum cleaning sys-
tems. The outlet from this ejector was connected by another
short hose to a metal box containing a canvas bag, woven back-
wards and forwards over metal frames to give a large surface
for the passage of air. The dust picked up by the suction of
the ejector was carried with the air into the box and there
separated from the air, which escaped through the canvas into
the apartment.
This form of renovator overcame some of the objections to
the former type in that there was no condensation of moisture
on the carpets, and it was possible to operate the renovator
under and around furniture, and even on portieres aiid other
hangings. However, the apparatus was rendered inefficient
by the resistance of the bag, causing a back pressure on the
injector which greatly reduced its air-drawing capacity.
Compressed Air Supplemented by Vacuxmi. — Shortly after
these two companies began operation, the Sanitary Devices
Manufacturing Company, of San Francisco, introduced a new
system of mechanical cleaning under the Lotz patents. This
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VACUUM CLEANING SYSTEMS
system used a renovator having a compressed air nozzle ter-
minating in a narrow slot, similar to the nozzles of the Amer-
ican and Thurman systems, but differing from them in that
the slot was fixed vertically, pointing downward. This nozzle
was surrounded by an annular chamber having an opening at
the bottom of considerable width. The whole formed a reno-
vator about 14 in. long and not over 2 in. wide at its base. In
addition to the compressed air connection to its nozzle, a second
hose, 1 in. in diameter, was connected to the annular space
surrounding the nozzle and led to a vacuum pump by which
the air liberated through the nozzle, together with the dust
which was liberated from the carpet, was carried from the
apartment. The contraction of this renovator is shown dia-
grammatically in Fig. 2.
/acuum'
Air.
PIG.
2. ANOTHER TYPE OF COMPRESSED AIR CLEANING
NOZZLE, SUPPLEMENTED WITH VACUUM PIPE.
As dust-laden air was not suitable to be carried through the
pump used as a vacuum producer, separators had to be pro-
vided to remove the dust from this air before it reached the
pump. The separators used consisted of two cylindrical tanks.
The air was introduced into the first tank in such a way that
a whirling motion was imparted to it, thus separating the
heavier particles of dust by centrifugal force. The second
tank contained water which was brought into initimate contact
with the air by means of an atomizer located in the pipe con-
nection between the two tanks, thus washing the air in a man-
ner somewhat similar to the familiar air washers used in con-
nection with mechanical ventilating systems. The air and
spray then entered the second tank, above the water line, where
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HISTORY OF MECHANICAL CLEANING 9
the entrained water separated on the reduction of velocity and
fell back into the water below, to be recirculated through the
FIG. 3. SEPARATORS USED WITH COMBINED COMPRESSED AIR
AND VACUUM MACHINES.
atomizer. The air passed on out of the top of the tank to the
pump. An illustration of these separators is shown in Fig. 3
Piston Pump the First Satisfactory Vacuum Producer.—
Various types of apparatus were tried as vacuum producers,
including an air ejector, such as was used with the Thurman
Compr^essor
_^ rStcamlnlef D/scharge>
I \Sfeam Exhaust) \ ^^^J^:::^^Vacuum Itifotke /
Vacuum Discharge-'' Compressor In fake-''
FIG. 4. PISTON TYPE OF VACUUM PUMP, MOUNTED TANDEM
WITH AIR COMPRESSOR.
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10 VACUUM CLEANING SYSTEMS
renovator, and found to be ineflfective due to its inability to
overcome the back-pressure necessary to discharge the air
through the hose, which was placed on its outlet. A rotary
pump was next tried, but, owing to the selection of an in-
efficient type, this was abandoned and, finally, a piston-type
vacuum pump, with very light poppet valves and mounted tan-
dem with the air compressor, was adapted and remained in use
with this system until straight vacuum was adopted, when the
air compression cylinder was omitted. This pump is illus-
trated in Fig. 4.
PIG. 5. MR. KENNEY'S FIRST RENOVATOR, VACUUM ALONE
BEING USED AS CLEANING AGENT.
In this system we see the first sanitary device to be intro-
duced into the field of mechanical cleaning, as the dust and
germ-laden air were removed entirely from the apartment and
purified before being discharged into the outside atmosphere.
The foulness of the water in the separators clearly showed the
amount of impurities removed from the air.
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HISTORY OF MECHANICAL CLEANING 11
These machines were mounted on wagons, similar to their
forerunners, and were also installed in many buildings as
stationary plants, among which were the old Palace Hotel and
the branch Mint, in San Francisco, and the old Fifth Avenue
Hotel, in New York City.
Systems Using Vacuum Only. — In 1902 David T. Kenney,
of New York, installed the first mechanical cleaning system in
which vacuum alone was used as the cleaning agent. Mr.
Kenney used a renovator with a slot about 12 in. long and 3/16
in. wide, attached to a metal tube which served as a handle,
PIG. 6. AIR COMPRESSORS ARRANGED FOR OPERATION AS
VACUUM PUMPS.
and to a ^-in. diameter hose and larger pipe line leading to
separators and vacuum pump. Mr. Kenney 's first renovator is
illustrated in Fig. 5.
Mr. Kenney used as vacuum pumps commercial air com-
pressors, the first of which was installed in the Frick Building
in 1902 and is illustrated in Fig. 6. Later he adapted the Clay-
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12 VACUUM CLEANING SYSTEMS
ton air compressor, with mechanically-operated induction and
poppet eduction valves on larger sizes, and single mechanically-
operated induction and eduction valves on the smaller sizes.
The separators used by Mr. Kenney differed from those used
by the Sanitary Devices Manufacturing Company in that they
contained several interior partitions, screens, and baffles, and
FIG. 7. SEPARATORS INSTALLED BY MR. KENNEY IN FRICR
BUILDING.
the air was drawn directly through the body of water in the
wet separator. The relative merits of these types of separators
will be discussed in a later chapter.
The separators installed by Mr. Kenney in the Frick Build-
ing, and which are practically the same as were used by him
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HISTORY OF MECHANICAL CLEANING 13
as long as he manufactured vacuum cleaning apparatus, are
illustrated in Fig. 7.
After his application had been in the patent office for about
tsix years he was granted a fundamental patent on a vacuum
cleaning system.
Renovator with Inrush Slot. — The Sanitary Devices Manu-
facturing Company then produced a carpet renovator using
vacuum only as a cleaning agent. This cleaner has a wider
cleaning slot that the cleaners usually furnished by Mr. Kenney,
about 5/16 in. wide, with a supplemental slot or vacuum breaker
opening out of the top of the renovator and separated from the
cleaning slot by a narrow partition extending nearly to the
FIG. 8. VACUUM RENOVATOR WITH INRUSH SLOT, INTRODUCED
BY THE SANITARY DEVICES MANUFACTURING CO.
carpet, as illustrated in Fig. 8. The relative merits of these
types of renovators will be discussed in a later chapter.
Shortly after the introduction of vacuum cleaning by Mr.
Kenney and the Sanitary Devices Manufacturing Company, the
American Air Cleaning Company published an interesting little
booklet entitled, ** Compressed Air Versus Vacuum,'' which set
forth in great detail the so-called advantages 'of compressed air
over vacuum as a medium of mechanical carpet cleaning, and,
apparently, proved that vacuum cleaners were much less effi-
cient than cleaners operated by compressed air. A year or two
later the Ameri-can Air Cleaning Company evidently had a
change of heart and began to manufacture these same ** in-
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14 VACUUM CLEANING SYSTEMS
efficient" vacuum cleaners. Their previous treatise on vacuum
cleaning, which apparently was not copyrighted, was repub-
lished by both the Sanitary Devices Manufacturing Company
and by the Vacuum Cleaner Company, which had acquired
Mr. Kenney's patents, and freely distributed. Thus this little
work of the Milwaukee company, instead of injuring their
competitors, was turned into good advertising for them and
required a lot of explanation from the Milwaukee company.
Steam Aspirators Used as Vacuum Producers. — The Amer-
ican Air Cleaning Company used a steam aspirator as its
vacuum producer and, unlike its predecessor, the air-operated
ejector, it made good and has also been used to a limited extent
by the Sanitary Devices Manufacturing Company. It is now
marketed by the Richmond Radiator Company, and its merits
will be discussed in a later chapter. The American Air Cleaner
Company also used as a vacuum producer the single-impeller
type of rotary pump, made by the Garden City Engineering
Company, which was also later adopted, to a limited extent, by
the Vacuum Cleaner Company. This will be discussed
further on.
The renovator used by this company was a single-slot type,
with J^-in. by 10-in. cleaning slot. These systems at once be-
came notable on account of the small size of the vacuum pro-
ducers used, the low degree of vacuum carried, and the vigorous
campaign of advertising which was conducted.
Several firms soon began to market vacuum cleaning systems
almost identical with that of Mr. Kenney, among which were
the Blaisdell Machinery Company, The Baldwin Engineering
Company, and The General Compressed Air and Vacuum
Machinery Company, the latter being the original Thurman
company.
The Vacuum Cleaner Company then began a series of in-
f ringment suits against nearly every manufacturer of vacuum
cleaning systems. In nearly every case the suit has resulted
in the offending company paying license fees to the Vacuum
Cleaner Company, and this concern has now abandoned the
manufacture of vacuum cleaners and has become a licensing
company. At this writing nearly twenty firms are paying
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HISTORY OP MECHANICAL CLEANING 15
license fees to the Vacuum Cleaner Company and there is one
suit now in the courts.
Piston Pump Used Without Separators. — A vacuum clean-
ing system of somewhat diflferent design was produced by two
former employees of the Vacuum Cleaner Company, Mr. Dunn,
the once well-known "Farmer Dunn" of the weather bureau,
afterward salesman for the Vacuum Cleaner Company, and Mr.
Locke, at one time this firm's engineer. This company was
first known as the Vacuum Cleaning Company, and, shortly
afterward, as the Dunn-Locke Vacuum Cleaning Company. No
separators were used with this system, but the dust-laden air
was led from the pipe lines directly into a chamber on the
pump, known as the ** saturation chamber,'' and there mingled
with a stream of water converting the dust into a thin mud.
The air, water and mud then passed through the pump, the
muddy water was discharged into the sewer, and the air into
the atmosphere. The vacuum producer used was a piston pump
without suction valves. With this system it was possible to
handle water in almost unlimited quantities and with this fea-
ture a system of mechanical scrubbing was attempted for which
great claims were made, none of which, however, were realized
in a commercial way.
These gentlemen sold their patents to the E. H. Wheeler
Company, which attempted to market the system in its original
form. It was found, however, that the piston pump was not
adapted to the handling of grit which was picked up by the
renovators, and a rotary pump, with single impeller and a fol-
lower was substituted. This system is now marketed by the
Vacuum Engineering Company, of New York, and is known as
the Rotrex system.
Mr. Dunn again entered the field of vacuum cleaning and
began marketing his machine a short time ago with a new form
of automatic separator discharging to sewer.
First Portable Vacuum Cleaner. — About 1905, Dr. William
Noe, of San Francisco, constructed the first portable vacuum
cleaner. This machine contained a mechanically-driven rotary
brush, similar to the brushes used in the familiar carpet sweeper,
for loosening the dust from the carpet. This dust was sucked
up by a two-stage turbine fan and discharged into a dust bag.
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16 VACUUM CLEANING SYSTEMS
mounted on the handle, similar to the bags on the compressed
air cleaners. The whole machine was mounted on wheels and
provided with a small direct-connected motor. This machine is
illustrated in Fig. 9 and is the original form of the well-known
Invincible renovator manufactured by the Electric Renovator
Company, of Pittsburgh. This company now produces a com-
plete line of stationary and portable vacuum cleaners, all of
which use multi-stage turbines. The sale of the product' of this
company, until recently, was controlled by the United States
Radiator Corporation.
FIG. 9. FIRST PORTABLE VACUUM CLEANER, CONSTRUCTED BY
DR. WILLIAM NOB, OF SAN FRANCISCO, IN 1905.
First Use of Stationary Multi-Stage Turbine Blowers. —
About 1905 Mr. Ira Spencer, president and engineer of the
Organ Power Company, which manufactured a multi-stage tur-
bine blower for organs, known as the **Orgoblow,'' organized
the Spencer Turbine Cleaner Company and marketed a vacuum
cleaning system, using a modification of the **Orgoblow" as a
vacuum producer. These machines were first constructed with
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HISTORY OF MECHANICAL CLEANING
17
sheet metal casings and had sheet steel fans, with wings riveted
on and mounted on horizontal shafts. The separators were sheet
metal receptacles with screens for catching litter. Light-weight
hose, 2 in. in diameter, was used to connect the renovators to
4-in. sheet metal pipe lines. A variety of renovators was pro-
duced for use with this system. Carpet renovators having
Inlet Tapptclx
fdr4'mPipe
.2Lc
U- -Zl'Scfuare
■i^jL.
PIG. 10. LATE TYPE OP SPENCER VACUUM CLEANING MACHINE,
OPERATED BY MULTI-STAGE TURBINE BLOWER.
cleaning slots varying from 10 in. by ^ in. to 20 in. by >4 iii-
were used, and a very complete line of swivel joints for con-
necting the renovators and the hose to the handles was de-
veloped. This system was operated at 5 in. vacuum, which was
much lower than that used by any other system, 15 in. being
standard at that time, and a much larger volume of air was
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18 VACUUM CLEANING SYSTEMS
exhausted under certain conditions than was possible with any
of the then existing systems. Owing to the large volume of air
exhausted and to the large size of the renovators, hose and pipe
lines, larger articles could be picked up than was possible with
any of the existing systems. A great deal of weight was
attached to this condition by the manufacturers, a favorite
stunt being to pick up nails, washers, waste, small pieces of
paper and even pea coal from a floor and finally to pick up a
quantity of flour which had first been carefully arranged for
the demonstration.
This* invasion of the vacuum cleaning field was considered by
the established manufacturers as a freak and the apparatus
was christened **the tin machine." Whenever it was in-
stalled in competition with other forms of cleaning systems,
the daily question asked by its competitors was, **Has the tin
machine fallen apart?" However, the tin machine did not fall
apart, but held its own with the other systems, even in its
crude and inefficient state. Finding that the construction he
had adopted was too flimsy and subject to abnormal leakage,
Mr. Spencer developed a new form of machine, using cast-iron
casing and welded fan wheels and adopted standard pipe and
fittings. He also brought out a line of sheet metal tools and
on the whole perfected a satisfactory cleaning system. One of
his machines of a later type is illustrated in Fig. 10.
Separators Emptying to Sewer by Air Pressure. — ^A new
form of vacuum cleaning system was introduced by Mr. Moor-
head, of San Francisco, who used an inrush type of renovator
having an inlet for air on each side of the cleaning slot.
The separator used with this system was a wet separator and
contained a screen cleaned by a rotary brush into which all
the dust contained in the air lodged. The pump used with this
system was generally of the piston type, fitted with a single
rotary valve, so connected to the valve stem that it could be
rotated thereon and the machine changed from a vacuum pump
to an air compressor in order that the contents of the separators
might be discharged into the sewer by air pressure when it
was desired to empty same.
This system was marketed by the Sanitary Dust Eemoval
Company, of San Francisco, and, later, was taken over by the
American Rotary Valve Company, of Chicago, which is now
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HISTORY OF MECHANICAL CLEANING 19
marketing same. It eliminates the manual handling of the dust
at any stage of its removal, a feature which is made much of
by its manufacturers, but one which is likely to cause some
trouble for the sewerage system if care is not exercised.
Machines Using Root Blowers as Vacuum Producers. —
The use of a Boot type of rotary pump as a vacuum producer
was first undertaken by the Foster and Glidden Engineering
Company, of Buffalo, which marketed the Acme system about
1907, the same company having previously built a simliar sys-
tem for the removal of grain from steam barges. The other
features of this sysrtem did not differ materially from those
already on the market.
Being familiar with the various uses to which this type of
vacuum pump had been adapted, the principal one being the
operation of pneumatic tube systems, the author suggested the
use of this type of vacuum producer about two years previous
to its introduction and was advised by one manufacturer that
such a type of pump was not suitable for vacuum cleaning.
The fallacy of this statement will be brought out in detail
in a later chapter.
The type of vacuum producer just described has been adopted
in many makes of vacuum cleaners, including the Hope, Con-
nellsville, Arco, and, lately, in the American Rotary Valve
Company's smaller systems.
During the past four years a score or more of new stationary
vacuum cleaning systems have been introduced, among which
are the Palm, a modification of the Dunn-Locke system; the
Tuec, a turbine cleaner; the Water Witch, which uses a water-
operated turbine as a vacuum producer, and the Hydraulic,
with water-operated ejector. At the same time a hundred or
more portable vacuum cleaners have been marketed. These
are of almost every conceivable type and form and are operated
by hand, electricity, and water power. Among them will be
found machines which are good, bad and indifferent, the effi-
ciency and economy of which will be discussed in a later chapter.
This nearly universal invasion of the vacuum cleaner field
by anybody and everybody looking for a good selling article,
establishes the fact that the vacumn cleaner is not a fad or
fancy, but has become almost a household necessity and has led
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20 VACUUM CLEANING SYSTEMS
large corporations to take it up as a branch of their business.
First, the Sanitary Devices Manufacturing Company and the
Vacuum Cleaner Company, the pioneers in the field, after a
legal battle of years, consolidated with a view of driving their
competitors from the field as infringers of the patents con-
trolled by the two organizations. The result of this was the
licensing of other companies. In an attempt to control the sale
of their type of apparatus notice was served on all users of
other types of vacuum cleaners that they were liable to prose-
cution for using infringing apparatus.
Later, the McCrum-Howell Company, a manufacturer of
heating boilers and radiators, secured control of the products of
the American Air Cleaning Company and the Vacuum Clean-
er Company and sold these machines to the trade for installa-
tion by the plumbers and steam fitters. The McCrum-Howell
Company has been succeeded by the Richmond Radiator Com-
pany, which is handling these vacuum cleaning machines.
Shortly afterwards, the United States Radiator Corporation
secured control of the Invincible and the Connellsville systems,
and, lastly, the American Radiator Company secured the Wand
system.
Thus we see that vacuum cleaning seems to be virtually in
the control of the manufacturers of heating apparatus, who
are also among the largest corporations in this country and
well able to control the future of this business to their liking.
As to the future of vacuum cleaning the author considers that
it is at present, like the automobile, at the height of its career,
and also, like the automobile, that it is a useful appliance to
mankind and that it has its proper place as a part of the
mechanical equipment of our modem buildings.
As to the type of vacuum cleaner of tlie future, the author
believes that these appliances will become standardized, just
as all other useful appliances have been, and that the form
that it will then take will be a survival of the fittest. What
that form may resemble the reader may more readily judge
when he has completed the reading of this book.
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CHAPTER II.
Requirements oi* an Ideal Vacuum Cleaning System.
Before a oomparison of the relative merits of any line of
applianees, used for any one purpose, can be intelligently made,
one must have either some form of that apparatus which we
consider as a standard for comparison that we may rate all
others as inferior or superior thereto, or else an ideal of a
perfect system must be assumed, and the measures with which
each of the various appliances approaches the requirements of
the ideal will establish their relative merits.
The author has elected to use the latter method in comparing
the various systems of vaxiuum cleaning, and it is neoessary,
therefore, to first determine what are the requirements we shall
impose on the ideal system.
An ideal vacuum cleaning system would be one which, when
installed in any building, will displace all appliances used for
dry cleaning in the semi-annual renovating or house cleaning,
the weekly cleaning or Friday sweeping and the daily supple-
mental cleaning. If our system be truly an ideal one, the
premises should never become so dirty as to require any semi-
annual cleaning at all, and, if the daily cleaning be anjnvay
thorough, there need be no weekly cleaning. This latter con-
dition may be governed by the will of the housekeeper or
janitor.
The compressed air cleaners first introduced were intended
for use only at the semi-annual cleaning and they were in
reality carpet renovators, which were assumed* as imparting to
the carpets all the beneficial results that could be obtained by
taking them up and sending them to a carpet-cleaning estab-
lishment, with the advantage over this latter method, that the
labor of removal and replacement of the carpets was rendered
unnecessary, but with the disadvantage that all the germ-laden
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22 VACUUM CLEANING SYSTEMS
air, used as a means of cleaning the carpets, was blown back
into the apartment, leaving the germs in their former abode.
This disadvantage, however, is partly ofBset by the fact
that while the majority of the grms in one's own carpet are
blown out at the carpet cleaners, a mixed company of germs
from your neighbors' and others' carpets, which may be in the
tumbling barrel at the same time with your own, are returned
to you with your carpet.
Neither of these conditions is ideal and we will expect our
ideal cleaner to completely remove from the premises, not only
the dust and dirt, but also the germ-laden air which is used as
a means of conveying this dirt.
For replacing the weekly and the daily cleaning, these earlier
renovators were not suitable, as in order to use same the fur-
niture must all be removed from the apartment
To accomplish this daily and weekly cleaning, the ideal
vacuum cleaner must replace the broom and dust pan, and
their inseparable companion, the duster, and must also super-
sede that time-honored mechanical cleaner, the carpet sweeper.
The reader will doubtless consider that in making this state-
ment the author is asking the vacuum cleaner to perform much
more than it is usually ci^ed on to do. However, we are now
discussing an ideal system, and the above requirements are not
absolutely beyond what can be accomplished by some of the
cleaning systems now on the market.
To accomplish this requirement the ideal cleaner must pick
up everything likely to be found on the floor which cannot
be readily picked up by hand. The character of this material
will vary greatly according to the uses of -the apartment
cleaned. In residences and offices, where carpets or rugs are in
use, cigar stumps and matches are usually deposited in cuspidors
and small pieces of paper in waste baskets, consequently there
should be nothing but dust to be removed from a residence and,
perhaps, mud and sand from the shoes of the many visitors,
in addition to the dust in an office.
However, there are special conditions likely to be met in many
cases; sewing rooms will be littered with basting threads and
scraps of cloth; department stores, with a great quantity of
pins; banking rooms with bands and large-sized bank pins; all
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REQUIREMENTS OF AN IDEAL SYSTEM 23
of which increase the requirements of the ideal system. A
cleaner which is perfectly adapted to one sort of apartment
will be entirely unsuited for another, and the ideal cleaner
win be one which can be readily adapted to all conditions likely
to be met in the building in which it is installed.
The ideal cleaner must be able to accomplish the above stated
requirements without the necessity of moving heavy pieces of
furniture out of or about the apartment; that is, it must be
capable of being efficiently operated under beds, tables and
chairs, around the legs of other heavy furniture, behind book-
cases, pianos, cabinets, etc., over curtains, draperies and hang-
ings, over walls, behind pictures and over mouldings and carved
ornaments, all without injury to any of the furniture or fittings
of the apartment, and with the least expenditure of energy by
the operator.
These conditions should be met with the fewest possible num-
ber of cleaning appliances, none of which should be provided
with small attachments liable to be lost or misplaced, and all
parts of the system, which must necessarily be moved about,
either before, after or during the cleaning operation, should be
of minimum weight and bulk, but of rugged and lasting con-
struction.
The ideal vacuum cleaner should be of such proportions and
provided with ample motive power to clean rapidly and
effectively.
For use in an office building the cleaner should be able to
thoroughly clean an average-sized office, including floor, walls,
furniture and fittings in from 10 to 15 minutes, and for resi-
dence work, should be of sufficient capacity to clean an apart-
ment, including floor, walls, curtains, draperies, pictures and
furniture in not exceeding 30 minutes.
The ideal system should be so arranged that any apart-
ment in the building can be cleaned with the least possible
disturbance and without affecting the use of any other apart-
ment, excepting perhaps, the corridors or hallways.
In large offices, drafting rooms and similar apartments, it
may become necessary to clean same while they are occupied;
therefore, our ideal system must be practically noiseless in
operation and must offer the least possible obstruction to the:
proper use of the room by its regular occupants.
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24 VACUUM CLEANING SYSTEMS
Necessity and Proper Location of Stationary Parts. — To be
of sufficient power to do rapid cleaning and in order to remove
from the building all dust and germ-laden air, the cleaning
system must necessarily contain some stationary parts. The
motive power can generally be <5onfined to these stationary
parts, and must, in such cases, be located within the building
to be cleaned. Therefore, it should operate with the minimum
of noise and vibration.
Machines located in office or other large buildings, containing
elevators or other complicated apparatus requiring skilled at-
tendance, which are provided with complicated control and
with other attachments, are not objectionable, and in such
eases simplicity should give way to efficiency, but unnecessary
complications should be avoided.
In residences and other small buildings, where the vacuum
cleaner is likely to be the only machinery installed, the sys-
tem must be one which requires the minimum attention and
must be capable of being started and stopped by any person of
average ability, without the necessity of going to the point
where the machine is located.
The power consumption of the ideal system should be a
minimum to accomplish satisfactory results and should be, as
nearly as possible, directly proportioned to the amount of clean-
ing being done. This requirement is most important in hotels,
where some cleaning is likely to be done at all hours, day and
night. In other words, vacuum must be **on tap'' and as
readily attainable at any point in the building as your water
or electric light. In office buildings, where a schedule of clean-
ing hours is fixed, and in residences where cleaning hours are
few and the capacity of the plant is rarely more than could be
attended to by one operator, this requirement is not of as
great importance.
Lastly, our ideal system, from the standpoint of the pur-
chaser, must be of such rugged construction, as will enable it
to operate efficiently for, at least, ten years and its mechanical
details such that it will operate continuously, without expert
attention, and that the annual expense for repairs during the
life of the machine will not exceed 5% of the first cost of the
system.
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CHAPTER III.
The Carpet Renovator.
In undertaking the comparison of a number of different
makes of any appliance, in order to determine the good and
bad points in each, where the apparatus is composed of a
number of separate and distinct parts, each having its proper
function, which they must perform in order to make the whole
apparatus effective, as in a vacuum cleaning system, it becomes
necessary to isolate temporarily each part and consider its
action, first, as a unit working under the most favorable con-
ditions, and, second, as a component part of the whole ap-
paratus in order to determine where the weak points in any
system occur and what modifications are necessary in the vari-
ous parts of the apparatus to make some vital part of the
whole more effective. It is further necessary to determine
what are the vital parts of the system in order that the other
parts may be accommodated to the effective action of that part.
Four Important Parts of Vacuum Cleaning System. — In
analyzing a vacuum cleaning system it naturally divides itself
into four parts, viz. : the cleaning tool or renovator, the air-
conveying system or hose and pipe lines, the separators or
other means of disposal of the material picked up, and the
vacuum producer.
The author considers that the renovator is the most impor-
tant part of the system and that the other parts should be made
of such proportions and with such physical characteristics as
will produce the proper conditions at the renovator to permit
it to perform its functions in the most effective manner.
As the vacuum cleaning system must be capable of cleaning
surfaces of a widely variable character many forms of reno-
vators are necessary. Of the various surfaces cleaned the
author considers that carpets and rugs comprise the most im-
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26 VACUXJM CLEANING SYSTEMS
portant, as well as the most difficult to clean effectively, so
that the carpet renovator will be oonsid^red first.
The Straight Vacuum Tool. — Various forms of carpet ren-
ovators have been and are in use by manufacturers of vacuum
cleaning systems. The first type of renovator to be considered
is that having a cleaning slot not over 12 in. long, with its
edges parellel throughout its length, and not over }i in. wide,
with a face in contact with the carpet not over }i in. wide on
each side of the slot. This form of renovator is illustrated in
Fig. 11 and is designated by the writer as Type A. The first
PIG. 12. TYPE B, WITH WIDE
FIG. 11. TYPE A, THE STRAIGHT SLOT AND WIDE BEARING
VACUUM TOOL. SURFACE.
of these renovators was introduced by Mr. Kenney and, as
finally adopted by him, was 12^ in. long, with J^-in. face and
with a cleaning slot ll^^ in. long and 5/32 in. wide. This form
of cleaner was termed the ** straight vacuum tool'' and is used
today by many manufacturers. Slight modifications in its form
and dimensions were made in some cases, as in the one manu-
factured by the American Air Cleaning Company. In the one
used in all tests by the writer on type A renovators, the slot
was reduced to 10 in. long and yi in. wide and the face of the
renovator was slightly rounded at the outer edges, leaving very
little surface in contact with the carpet.
A renovator of this t.>T)e is easily operated over any carpet
even when a considerable degree of vacuum exists within the
renovator itself. It has met with favor when used with the
piston type of vacuum pump without vacuum .control, as was
the case with the earlier systems. However, w'hen a very high
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THE CARPET RENOVATOR 27
degree of vacuum occurs within the renovator it has a tendency
to pull the nap from the pile of the carpet.
Soon after the introduction of this form of renovator, some
users of same, particularly in San Francisco, complained that
while the renovator effectively removed the dust from carpets
it failed to pick up matches and other small articles and pre-
liminary or subsequent cleaning was necessary in order to
remove such litter.
To overcome this difficulty Mr. Kenney increased the width
of the cleaning slot to nearly J4 in., with the result that when
a high degree of vacuum existed within the renovator, which
often occurred where no vacuum control was used, it stuck to
the carpet, rendering its operation difficult and, at the same
time, doing great damage to the carpet. Hence, its use with the
piston type of vacuum pumps was abandoned.
Mr. Kenney then modified this wide slot renovator by making
the face of same much wider, thus having more surface in
contact with the carpet on each side of the slot, preventing the
renovator from sinking into the nap of the carpet. This type
of renovator is illustrated in Fig. 12 and has been designated
as Type B. While not as destructive to the carpets, when a
high degree of vacuum existed under the same, it still pushed
hard and was not as rapid a cleianer as the narrow-lipped Type
A renovator.
Renovator with Auxiliary Slot Open to Atmosphere. — •
The renovator introduced by the Sanitary Devices Manufac-
turing Company differed widely from the former type^ in
that it was provided with an auxiliary slot, open to the atmos-
phere through the top of the renovator, which communicated
with the slot open to the vacuum by a space of 1/32-in. under
the partition separating the slots. The cleaning slot was made
5/16-in. wide and the face of the renovator was made 2-in. wide,
which gave a contact of 13/32-in. in front of the inrush slot
and 21/32-in. in the rear of the cleaning slot. This form of
renovator is illustrated in Fig. 13 and is designated as Type C.
The auxiliary slot or vacuum breaker permitted air to enter
the cleaning slot even when the renovator was placed on a
surface plate, and, owing to this feature, a high degree of
vacuum never existed within the renovator. It was always
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VACUUM CLEANING SYSTEMS
easy to operate and did not damage the carpet. Owing to the
wide slot, articles of considerable size could be picked up, and
there was always an abundance of air passing through the
renovator to produce a velocity in the hose and pipe lines
sufficient to carry any heavy articles picked up.
The vacuum producer, control apparatus and the proportions
of the hose and piping used at that time made the degree of
vacuum in the renovator a function of the quantity of air
passing, with wide limits of variation under existing conditions,
and this fonn of renovator is practically the only one which
will do effective cleaning, including the picking up of litter,
without undue wear on carpets, when used with a system
having the above-stated characteristics. This renovator, how-
ever is not without its faults. Owing to the wide surface in
contact with the carpet, a considerable degree of vacuum is
necessary in order that any air shall enter the renovator under
FIG. 13. TYPE C, WITH AUX-
ILIARY SLOT, OPEN TO
ATMOSPHERE.
FIG. 14. TYPE D. WITH TWO
CLEANING SLOTS.
the faces of same and, as the air entering the inrush slot pre-
vents the formation of such vacuum within the renovator, very
little air enters the renovator between itai face and the carpet.
When the renovator is operated on a carpet having a glue-sized
back, no air enters througih the carpet, therefore all air entering
the renovator must come through the inrush slot and under the
partition separating same from the cleaning slot. Under these
conditions only one side of the vacuum slot is effective and this
effective side is raised above the surface of the carpei.
When operated on an ingrain or other loose-fabric carpet,
much air enters through the fabric of the carpet, due to the
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THE CAKPET RENOVATOR 29
wide cleaning and inrush slots, in addition to the quantity of
air entering through the inrush slot, making this renovator,
when operating under these conditions, use an unnecessary
amount of air. Apparently, this renovator has been designed
to prevent the formation of any great degree of vacuum under
same and such a design has resulted in a greater volume of
ftir at a lower vacuum passing through than through renovaltors
of. other types.
This property of the renovator raises the question whether
^;he quantity of air or the degree of vacuum in the renovator
is most essential for the removal of dirt from carpets. Tests
made by Mr. S. A. Reeve, consulting engineer for the Vacuum
•Cleaner Company, with this type of renovator, with the in-
rush open and repeated with the inrush closed, disclose the
fact th'art; it does more effective cleaning with its inrush closed,
while the volume of air passing is considerably less with the
inrush closed. The degree of vacuum was greater, which tends
to indicate that the vacuum within the renovator is the most
important factor.
An extract from the affidavits of Mr. Reeve in one of the
numerous patent suits will show his explanation of this phe-
nomenon : * * If we examine more closely into the actual process
whereby such a sweeper succeeds in extracting dust from car-
pets, etc., it will appear that the actual cleaning is effected
.at the periphery of the slot in the lower surface of the sweeper.
It is accomplished chiefly by the development of local changes
.of air pressure at the lips defining this slot, incidentally to the
movement of the tool over the carpet. These changes cause
the air occupying the interstices between the dust particles to
.expand suddenly, thus * raising the dust.' To a lesser degree,
-the scouring is effected by highly localized air currents of con-
siderable velocity, engendered where the tool comes in contact
with the carpet. These air currents pick up the dust which
has already been expanded or raised by pressure change. They
will be of higher velocity, and therefore more effective, the
better the contact of the tool with the carpet. The same is
true of the pressure changes.
'*A11 this action depends for its intensity, speed and effec-
;tiveness, not on the vacuum existing at the pump or in the
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30 VACUUM CLEANING SYSTEMS
separators, but upon the vacuum prevailing within the sweeper
head itself."
Renovator with Two Cleaning Slots. — Another form of
renovator was introduced by the Blaisdell Machinery Company
which contained two cleaning slots each 3/16-in. wide and 12-in.
long, separated by a partition j4-iii- wide in contact with the
surface of the carpet, as indicated in Fig. 14 (Type D). While
this form of renovator has a greater area of cleaning slot than
Type A, its individual cleaning slots are no wider; therefore,
it cannot pick up anything larger than can be picked up by
Type A. As no air can enter under the partition it oan
do no more effective work as a dust remover when operated on
a carpet with a glue-sized back and its only advantage over a
cleaner of Type A is that when operated on a loose-fabric carpet
more air can pass through the fabric into the cleaning slot,
thus giving a greater variation in the quantity of air exhausted
when operated on carpets of different texture, a condition which
is undesirable when used with a system having characteristics
previously described.
Tests of this type of renovator, made by Mr. Reeve, are given
later in this chapter.
Renovator with Inrush Slots on Each Side.-— Another form
of renovator, introduced by Mr. Moorhead, is illustrated in
Fig. 15 (Type E). This is a modification of Type A in that
an inrush slot is provided on each side of the vacuum slot,
these inrushes being hinged members which form the sides
of the cleaning slot. This cleaner has the advantage over Type
C renovator in that it can take air from either side, but in
action it takes air from but one side at any time. Its inrush
will not become entirely clogged, but its mechanically-moving
parts in contact with the dust and lint picked up will easily
become inoperative and are as like as not to become caught
wide open when the air entering the cleaner will not come into
intimate contact wtih the carpet. In that event, its cleaning
efficiency will be greatly reduced. The author has not had an
opportunity to make any comparative tests of this form of
renovator.
When Mr. Spencer introduced the centrifugal fan as a
vacuum producer, he also brought out a series of carpet reno-
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THE CARPET RENOVATOR
31
vators of various forms and sizes. One had a cleaning slot
54-in. wide and 10-in. long, another a slot 15-in. long, j4-iii-
wide at its fend, increasing to ^-in. at the center. Another
had a slot 20-in. long and J^-in. wide, and finally he adopted a
tool with a cleaning slot 15-in. long and ^-in. wide throughout
its length. This is merely the re-entrance into the field of the
wide-slot tool first used by Mr. Kenney and its successful opera-
tion depends on its use with a vacuum producer of such char-
acteristics and a hose and pipe line of such proportions that
practically a constant vacuum is maintained within the reno-
vator, regardless of the quantity of air passing through the
tool. The latest form of this renovator, as used by Mr. Spencer,
is illustrated in Fig. 16. At the time that the writer made tests
on renovators of this make, the majority of the tests were made
with a renovator having a cleaning slot 10-in. long and ^-in.
PIO. 16. TYPE B, WITH INRUSH
SLOT ON BACH SIDE OF
VACUUM SLOT.
FIG. 16. TTPB F, AN BXAO-
GBRATED FORM OF
TYPE B.
wide. This renovator is designated as Type F, while the
15-in. X j4-i^- *o ^-in. slot is designated as Type F^.
About seven years ago the Supervising Architect of the
United States Treasury Department gave consideration to the
use of a carpet cleaning test to determine the acceptability of
any vacuum cleaning system which might be installed in any of
the buildings under his control. The author was instructed
to make a series of tests of carpet renovators, with a view of
determining: (1) the feasibility of using a carpet cleaning test
to determine the merits of a vacuum cleaning system; (2) to
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32 VACUUM CLEANING SYSTEMS
fix the requirements to be incorporated in a specification where
the acceptance of the system was dependent on a satisfactory-
carpet cleaning test, to be made at the building after the com-
pletion of the installation; (3) to determine what requirements,
other than a cleaning test, would be necessary to obtain a
first-class cleaning system.
The record of many such tests was shown to the author, shortly
before he began making tests. These purported to have been
made by Prof. Miller at the Massadiusetts Institute of Tech-
nology, with a pump furnished by the Sanitary Devices Manu-
facturing Company, in which the efficiency of the inrush type
of renovator (Type C) and the straight vtacuum renovator
(Type A) was compared. The results of these tests, as given
in a brief resume, which was distributed by the Sanitary
Devices Manufacturing Co., indicated that the Type C reno-
vator was the more rapid and efficient cleaner.
The author learned that these tests were made by the under-
graduate students as a part of the regular laboratory work,
and that later a series of tests was made as the basis of a
thesis by Messrs. Paterson and Phelps in 1906, using the above-
described apparatus. The following year another series of tests
was made by Mr. Stewart R. Miller, as the basis of an under-
graduate thesis, in which the efficiencies of the piston pump and
inrush sweeper of the Sanitary Devices Manufacturing Co.
were compared with those of the steam aspirator and straight
vacuum renovator of the American Air Cleaner Company. A
copy of this thesis was furnished the author by the Sanitary
Devices Manufacturing Company shortly after the completion
of the tests miade by the author.
The relative efficiency of the two types of renovators reported
by these tests differed widely in each case, an occurrence
which is liable to happen where undergraduate students are
engaged in such work. They were, therefore, considered as of
doubtful reliability.
The author could find no record of any tests made by anyone
of longer experience and, indeed, these were the only tests of
which he could find any record.
As the author desired to specify a cleaning test which could
be readily repeated at the building in which the cleaning sys-
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THE CARPET RENOVATOR 33
tern was installed, which building was likely to be located in
any part of the United States, no exhaustive laboratory methods
were desired or attempted. As the building was likely to be
located in a city where no other vacuum cleaning systems were
then installed and in a new building in which no dirty carpets
were available, and as it was not desirable to have the con-
tractor furnish the material for the test, it was considered nec-
essary to use some material in soiling carpets which would be
readily obtainable anywhere, which could be readily brought to
a standard, and which, when worked into the carpets in a
reasonable length of time, would be as difficult to remove as
the dirt found in the average dirty carpet.
Tests on Dirty Carpets. — As no tests of cleaning an actually
dirty carpet were on record, quicksand having been used in the
Institute of Technology tests, it was necessary to first clean
some carpets that had been soiled in actual daily service in
order to obtain a standard with which to compare the results
in removing various substances, which it was intended to try
as a substitute for dirt. A carpet which had been in actual use
for a number of years on the floors of the old United States
Mint building, in Philadelphia, and receiving the ordinary
amount of cleaning, was procured. This was a Brussels car-
pet with a glue-sized back, containing about 20 sq. yds. It
was divided into three approximately equal parts.
An indicator was attached to the vacuum pump for taking
air measurements, and it was found that there was consider-
able leakage of air into the system through the connections to
the separators and at other points, therefore the pump was
operated with 22 in. of vacuum in the separator and a card taken
with all outlets closed and the amount of leakage noted. Dur-
ing the tests this degree of vacuum was always maintained in
the separators and pipe lines and the vacuum in the renovator
was varied throughout the tests by throttling the hose cock.
This manner of making tests gave a practically constant leak-
age which was deducted from the quantities shown by the
indicator cards taken with the renovators in operation.
As the writer had already made many tests of the efficiency
of various types of vacuum pumps as air movers under various
degrees of vacuum, and as the capacity of the pump available
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VACUUM CLEANING SYSTEMS
was far in excess of that required to operate one renovator,
no attempt to obtain the efficiency of the plant as a unit was
made. Instead, the vacuum at the hose cock was adjusted until
the degree obtained was what the writer had found to be within
the limit obtained in practice. The resulting vacuum at the.
renovator was then noted.
Each piece of carpet was cleaned during six periods of one
minute each, using a different vacuum at the tool for each
piece of carpet. The carpets were weighed at the beginning
of the test and after each one-minute period. At the conclusion
of these tests each carpet was cleaned until no change of weight
occurred after two minutes' cleaning. They were then con-
sidered as being 100% clean and this standard was made a
basis for computing the percentage of dirt removal. A reno-
vator of Type C was used in these tests.
Shortly afterward a similar test was made on a dirty carpet
of 4.6 sq. yds. area, using a renovator of Type F. This carpet
was also a Brussels, with glue-sized back, which had been in
use in the shoe department of a large department store in
Hartford. These carpets contained approximately 2 oz. of dust
per square yard, none of which was visible on the surface, and
they were probably as. clean as the average carpet after being
TABLE 1.
Cleaning Tests of Dirty Carpets.
Type of Renovator.
Vacuum in renovator, in. Hg
Air exhausted, cu. ft. per min
Material removed, per cent, of total,
1 min
Material removed, per cent, of total,
2 min
Material removed, per cent, of total,
3 min..
Material removed, per cent, of total,
4 min
Material removed, per cent, of total,
5 min ^
Material removed, per cent, of total,
6 min
H. P. per ounce dust
Ounces dust per minute
H. P. at renovator
2 4^
16 27
50 60
72 81
85 90
90 95
93 98
95 100
0.037 0.147
1.9 2.0
0.07 0.29
<^
1
24
2/.
37
4
44
Zl
39
47
52
59
63
59
66
71
61
72
83
66
75
87
67 82 90
0.045 0.116 0.252
1.34 1.64 1.8
0.06 0.19 0.45
59
35
55
69
n
84
89
0.261
1.78
0.475
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THE CARPET RENOVATOR
35
gone over with a carpet sweeper or after a light application
of a broom.
As the sizes of the carpets used in making the tests were not
always the same, allowance has been made for this variation by
using, in the case of Type F renovator, instead of the true
time, a calculated time which allows each renovator the same
time for cleaning 1 sq. yd. of carpet. For instance, in the case
of the small carpet cleaned with Type F renovator, an interval
of 60X4.6—6, or 46 seconds, was taken as equal to one minute's
cleaning of the carpet with types A and C renovators. Such
interval is stated and plotted as one minute in the table opposite,
which gives the results of cleaning dirty carpets with the three
types of renovators.
Type A Renovator Most Efficient on Dirty Carpets. —
The results of the tests of the three types of renovators, eacli
100
80
o
L
X
A-
>^
r^'
'c-
^
—
/
^
^!
F
/
y^
;v^
1
f
//
'
/
A
/
lOz.
h
/
'/
t
Jl
l!
\
1 4 6
Time of Cleaning, Minutee
PIG. 17. TESTS OF THREE RENOVATORS ON DIRTY CARPETS.
when it was operated with the highest vacuum under the reno-
vator, are plotted in Fig. 17 in order tlhat a ready comparison
may be made. This curve indicates that Type A renovator
does more effective cleaning in less time than either of the other
two types tested.
Referring to the second line of the table, which gives the
degree of vacuum obtained in the renovator during the tests,
it will be noted that the highest vacuum attained with each
type of renovator is practically the same. This degree of
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36 VACUUM CLEANING SYSTEMS
vacuum was obtained with the average vacuum at the hose cock,
using 100 ft. of hose in each case, and corresponds to that ob-
tained in the commercial operation of each of the renovators
with the vacuum producers ordinarily used, which was 15 in. in
the case of Type C, 10 in. in case of Type A, and 5 in. in case
of Type F, the hose being the size used by each of the systems
as marketed.
The third line, which shows the cubic feet of free air per
minute passing the renovator, indicates that Type A renovator
requires much less air at the same degree of vacuum than
either of the other types to do better work.
From the readings in these two lines the horse power required
at the renovator, to move the air that passes same is obtained
with 100% efficiency adiabatic compression. The results are
tabulated in the ninth line of the table.
This indicates that Type A renovator does more effective
work with about 50% of the power required by either of the
other types of renovators.
The tenth line gives the rate of cleaning and again shows
Type A renovator to be the most rapid cleaner.
The eleventh line gives the horse power required at the reno-
vator when in operation, from which it will be seen that effec-
tive cleaning cannot be accomplished with less than % H. P.
at the renovator.
Attention is called to the great reduction in power in case of
Type A renovator when the vacuum at the tool is reduced from
4^ in. to 2 in. and to the small reduction in the efficiency
which results from this great reduction in power. This is
not the ease with the Type C renovator, where there is a con-
siderable reduction in the already low efficiency with each
reduction in the vacuum. This characteristic of Type A reno-
vator is discussed further on in the chapter on hose.
Tests of Carpets "Artificially" Soiled. — Having determined
the efficiency of the various types of renovators when operated
on dirty carpets, the author then attempted to find some sub-
stance easily obtained anywhere which could be used as a sub-
stitute for actual dirt, and which would give approximately
equal results with these obtained on dirty carpets.
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THE CARPET RENOVATOR 37
A test of this character was made by the author some time
previous to the tests of dirty carpets and was made on a Wilton
velvet rug of about 12 sq. yds. area. The material spread on
same was ordinary wheat flour, as used in demonstrations, 3 lbs.
of which were placed on the rug and rubbed in with sticks of
wood as well as possible and the rug cleaned for three minutes,
using a Type A renovator attached to the separator with 50 ft.
of 1-in. diameter hose. The results were as follows:
Vacuum at Separator, Per Cent. Dikt
Ins. Mercury. Removed.
5 95
10 ' 98
15 98
The vacuum at the renovator was not measured at the time
of making this test and its amount is not exactly known, but
further tests with this type of renovator under nearly the same
conditions gave the following results:
Vacuum at Hose Cock, Vacuum in Renovator,
Ins. Mercury. Ins. Mercury.
5 3
10 6y2
15 9
and it is probable that the vacuum at the renovator during
these tests was approximately the same.
Comparison of the results of this test, in which 4 sq. yds. of
carpet were cleaned per minute, wtih those of the tests of dirry
carpets, in wMch only 1 sq. yd. was cleaned per minute, indi-
cates that wheat flour is not a suitable substitute for dirt in
making a carpet cleaning test.
The author, believing that flour is of sufficient fineness, but
not of sufficient weight, tried Portland cement, which is very
heavy and at the same time exceedingly fine, as a substitute for
dirt in soiling carpets. The same carpet that had been cleaned
in Philadelphia was used and 6^2 oz. of cement was worked
into the same. It was then cleaned with a Type C renovator,
with a vacuum of 2}4 in. hg. at the renovator and 95% of the
cement was removed in two minutes' cleaning, as against 59%
of the dirt in the carpet when received.
Ordinary dirt, taken from some flower jyots which had been
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VACUUM CLEANING SYSTEMS
left dry for some time, was then tried with the same carpet,
wamg a Type C renovator aand 1 in. hg. With this arrange-
ment, 71^% of the dirt was removed in two minutes as against
52% of the dirt in the carpet as received.
This dirt was then mixed with water to a thin mud and
spread over the carpet and the carpet dried before cleaning.
Then 11J4 oz. of this material was worked into 6 sq. yds. of
carpet and a Type C renovator removed 100% of this in four
minutes' cleaning, with a vacuum of 2^ in. hg. at the tool as
against 72% of the dirt in the carpet as received.
The author's ingenuity being about exhausted, he referred
to the test of Mr. Stewart R. Miller in which quicksand which
would pass a 50-mesh to the inch screen was used, a long-
napped Bmssels carpet being filled with 5^ oz. per square
yard and cleaned with Types A and C renovators.
This test indicated that a nearer approach to the results in
cleaning dirty carpets was possible with this substance than
with any which the author had tried. The author repeated Mr.
Miller's test, using a Type F renovator, 10-in. x ^i-in. cleaning
slot, and also a Type P^ renovator, 15-in. x J^-in. to ^-in.
cleaning slot. In duplicating these tests the author was asso-
ciated with Mr. E. L. Wilson, a graduate of the Institute, who
TABLE 2.
Cleaning Tests of Carpets Filled with 5J^ Oz. of Quicksand per
Square Yard of Carpet.
Type of Renovator.
A
C
F
4y2
4
3J4
27
44
59
60
53
66
75
65
83
82
74
94
87
82
100
92
87
95
93
0.09
0.138
0.084
3.2
3.1
5.3
F'
Vacuum in- renovator, in. hg
Air exhausted, cubic feet per minute
Material removed, per cent, of total, 1 min.
Material removed, per cent, of total, 2 min.
Material removed, per cent, of total, 3 min.
Material removed, per cent, of total, 4 riiin.
Material removed, per cent, of total, 5 min.
Material removed, per cent, of total, 6 min.
H. P. per ounce sand
Ounces sand per minute
3^
54
53
75
86
94
100
0.109
4.0
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THE CARPET RENOVATOR
39
was familiar with the methods used by Mr. Miller. With his
assistance, the conditions of Mr. Miller's tests were almost ex-
actly duplicated. The results of Mr. Miller's and the author's
tests are given in the table opposite, correction being made in
the time of cleaning proportional to the size of oarpets used, to
allow the same time for cleaning 1 sq. yd. of carpet by each
renovator*
The results of these tests are shown graphically in Fig. 18.
Comparison of these curves with the curves of cleaning dirty
carpets (Fig. 17), shows a falling off in the efficiency of clean-
ing by Type A renovator while there is a gain in the efficiency
in cleaning by all of the other types of renovators. Type C
2 4 « •
Time of €leontnc|,MinutM
PIG. 18. CLEANING TESTS OP CARPETS PILLED WITH QUICKSAND.
being now nearly as efficient as Type A, while Types F and F^
renovators are now more efficient than Type A. This result
must be due either to the increased quantity of material to be
removed, 5^^ oz. per square yard in case of the sand as against
2 oz. per square yard in case of the dirt, or else to the change
in the character of the material removed, the sand having much
sharper surfaces than would be encountered in case of dirt
which must necessarily be ground under the feet before it
reaches the carpet, or to the longer nap of the carpet.
In order to determine the effect of the increase in the quan-
tity of material on the results, the tests were repeated using
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VACUUM CLEANING SYSTEMS
1 oz. of sand per square yard of carpet in each case, omitting
the test on Type F^ renovator.
These tests were made on a glue-sized back, short napped
Brussels carpet, using as much sand as could readily be worked
out of sight in this carpet. The results of tests are given in
the following table:
TABLE 3.
Cleaning Tests Using 1 Ounce of Sand per Square Yard of Carpet.
Type of Renovator.
Vacuum in renovator, in. hg
Air exhausted, cubic feet per min
Material removed, per cent, of total,
1 min
Material removed, per cent, of total,
2 min
Material removed, per cent, of total,
3 min
Material removed, per cent, of total,
4 min
Material removed, per cent, of total,
5 min
Material removed, per cent, of total,
6 min
H. P. per ounce sand
Ounces sand per minute
A
2
16
4^
27
48
54
70
87
91 100
100
—
0.047 0.143
1.5 2.0
1
24 37
45 48
60 63
73 75
76 81
2^ 4
44
50
65
77
88
97
— 92 102
0.06 0.195 0.44
— 0.92 1.02
3^
59
50
73
87'
100
0.223
2.11
The results of these tests at the higher vacua are shown
graphically in Fig. 19. Comparison of these curves with those
obtained when removing sand from a long napped carpet (Fig.
18), shows:
First, a marked increase in the efficiency of Type A reno-
vator, this being slightly better than obtained when cleaning
a dirty carpet.
Second, practically no change in the efficiency of Type C
renovator.
Third, a small decrease in the efficiency of Type F renovator,
which still shows a much higher efficiency than when cleaning
dirty carpets.
In order to determine how much, if any, of these changes
in the behavior of the renovators was due to the increase in
the quantity of material to be removed, the horizontal line,
representing 1 oz. of sand remaining in the long-napped carpet,
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THE CARPET RENOVATOR
41
was drawn on Fig. 18 and, using this as a base line, it will be
seen that Type A renovator removes this remaining material
in three minutes, the same time as was required to remove the
same amount from the short-napped carpet. However, the first
4>4 oz. of sand have been removed from the long-napped carpet
in three minutes, or at a rate 4j4 times as fast as the last
1 oz. was removed. This indicates that the narrow slot reno-
vator is capable of handling more material than is likely to be
encountered in any dirty carpet and that the apparent decrease
in the efficiency of this renovator is not due to the increased
quantity of material to be removed.
It will be noted that the Type C renovator removed the last
1 oz. per square yard from the long-napped carpet in the same
nor
u
£
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Time of Cleanlrtoj,Mlnu*i*
PIG. 19. CLEANING TESTS USING 1 OZ. OP SAND PER SQUARE
YARD OP CARPET.
time that was required by Type A renovator, while it needed
nearly twice as long to remove this amount of material from
the short-napped carpet (Fig. 19). This renovator, however,
was slower in removing the first 4^ oz. per square yard.
Type F renovator removed the last 1 oz. per square yard
from the long-napped carpet in two minutes, while it required
twice this time to remove the same amount from the short-
napped carpet. This renovator also removed the first 4^ oz.
per square yard from the long-napped carpet in two minutes,
while it required three minutes for Type A and 3^ minutes
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42 VACUUM CLEANING SYSTEMS
for Type C renovators to remove the same quantity. It is,
therefore, evident that sand is removed more rapidly from a
long than from a short-napped carpet when a wide slot reno-
vator is used. The same time is required to remove small quan-
tities of sand from a long or short-napped carpet with a nar-
row slot.
This phenomenon is probably due "to the sand being held in
the carpets by the adhesion^ of its sharp edges to the sides of
the nap, this being more pronounced in the case of the long-
napped carpet where it is easier to work the material out of
sight without grinding it into intimate contact with the pile
of the carpet. When the wide-slot renovator passes over the
carpet, the carpet is arched up into the slot and the upper ends
of the nap separated. The longer the nap or the wider the
slot, the greater will be this separation. With the long-napped
carpet this separation will at once release the sand, while, in
case of the short nap, there is less separation and also more ad-
hesion of the sand to the pile of the carpet, due to the harder
grinding necessary to work the material out of sight. There-
fore, the wider the cleaning slot used, the faster the sand will
be removed, as is evident by comparison of the tests of Types
F and F^ renovators on the long-napped carpet.
With the narrow slot renovator the arching of the carpet
under the cleaning slot is negligible and no advantage is gained
when using this type of renovator to remove sand from a long-
napped carpet. It is also possible that the nap of the carpet
may be longer than the width of the cleaning slot, in which
case the nap will not snap back to a vertical position when it is
under the cleaning slot, but will be pressed down and will im-
pair the action of the renovator. The author considers that
the width of the slot should always be greater than the length
of the nap of the carpet in order to do effective cleaning.
Shortly after making the above-described tests, the author
had occasion to make somewhat similar tests, using a sand-filled
carpet, in an attempt to try out a proposed carpet cleaning
test intended to be used as a standard for use in specifications
for a vacuum cleaning system. When a Wilton carpet was
used, it was found that neither Type Aor C renovator would
fulfill the test requirements, which were within the results
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THE CARPET RENOVATOR 43
obtained in tests already described. Unfortunately a Type P
renovator was not available, but the author is of the opinion
that it would have done better.
The test was then repeated, using a Brussels carpet and the
test requirement was easily met. This discovery led the author
to make further tests of carpets of different makes, filled with
sand and cleaned under the same conditions which yielded far
from uniform or satisfactory results, and the use of a cleaning
test, where artificially-soiled carpets are used, was abandoned.
The author is of the opinion that no substance artificially
applied to a carpet, other than regular sweepings, will give any-
thing like the same results -as will be obtained in actual cleaning.
Sand seems to be the only substance which can be worked into
the carpet, that is nearly a^ difficult to remove as the actual
dirt found in carpets, and, in many cases, this material gives
results that are misleading and unfair to some types of reno-
vators. No test which uses a carpet artificially soiled with
artificially prepared dirt is considered to be of any value in
determining the relative efficiency of various types of carpet
renovators.
A series of tests was made by Mr. Sidney A. Reeve con-
sulting engineer, of New York City, in October, 1910, at the
works of the Vacuum Cleaner Company, Plainfield, N. J., in
which the conditions were such as would give much more uni-
form results than were possible in the tests made by the author.
In making these tests the renovator was held firmly clamped
in any desired position in a wooden carriage rolling upon a
straight wooden track. The portion of the carriage supporting
the sweeper is attached to the remainder of the carriage by
hinges, so that the sweeper is free to seek its own contact with
the carpet The carriage was given a reciprocating motion by
its attachment to a large bell crank, which in turn received
its motion from the factory shafting. The construction of the
bell crank was such that the driving power could be readily
thrown in and out of gear at any time.
The carpet was stretched tightly upon a platen which was
fitted for movement across the line of motion of the sweeper,
along straight guides suitably attached to the floor. The ends
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44 VACUUM CLEANING SYSTEMS
of the carpet were first wedged tightly in clamps and the
clamps wedged apart so as to stretch the carpet.
The tests consisted in first weighing the carpet, then stretch-
ing it upon the platen, then sprinkling thereon a suitable and
known weight of dirt taken from the separators of the com-
pany's machines, from which the lint and coarse, fibrous ma-
terial had been sifted and which was thoroughly trodden into
the fibres of the carpet, whereupon the sweeper was set in motion
for a given number of strokes.
In nearly all cases the tests were repeated upon the same
piece of carpet, with the same charge of dirt, by repeatedly
placing the carpet in the frame and giving it a further and
more extended cleaning.
All tests were corroborated by repetition before being ad-
mitted to the records. Every effort was made to have the tests
approach the conditions occurring in actual practice, as nearly
as possible, and still keep them definite and measurable.
The carpet used was a Wilton, of the standard width of
27 in. and something over a yard long, and the sweeper was
given a stroke of 34 in. at the rate of 40 strokes per minute.
The sweepers were attached to a 6-ft. tubular handle, 15/16-in.
inside diameter, and connected to the separator by 50 ft. ot*
1-in. diameter hose.
Before making any tests, the piston pump used in the experi-
ments was calibrated by pumping through a rotary meter
and the amount of air moved per revolution for each degree
of vacuum from open inlet to closed system was carefully de-
termined. In making the tests of various renovators, each reno-
vator was allowed to pass the same amount of air as the others
tested in comparison therewith and the vacuum at the reno-
vator and at the separator was allowed to be what was neces-
sary to pass this known amount of air through the renovators.
This method is widely different from that used by the author
where the degree of vacuum at the renovator head was deter-
mined and used as a limiting factor, the quantity of air being
allowed to vary as necessary to produce this vacuum.
The results of three series of tests are given in Fig. 20, which
shows those obtained with Kenney Type A renovators, having
a face 12>^ in. x % in. and a cleaning slot ll^^ in. x 5/32 in:
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THE CARPET RENOVATOR
45
Curve A was made with the angle of the handle such as would
give as near as possible a perfect contact of the sweeper with
the carpet. Curve B was made with the sweeper handle canted
5° below the proper angle. Curve C was made with the sweeper
handle raised approximately 15° above the proper angle. The
ordinates represented the amount of dust in the carpet in
40ths of a pound, also reduced by the author to ounces, and the
abscissae the number of strokes made by the sweeper.
2 =3
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80
Number of Strokes of Sweeper
PIG. 20. THREE SERIES OP TESTS WITH KENNEY TYPE A
RENOVATORS.
Curves B and C show the loss in efficiency which occurs when
the renovator is canted from its proper position on the carpet.
This falling off in efficiency will necessarily be greater the
wider the face of the renovator, as is shown in further tests
by Mr. Reeve, using a Type C renovator, which tests also
show that this renovator gives a slightly higher efficiency
when operated with the inrush slot stopped, as is shown in
Fig. 21.
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r
46
VACUUM CLEANING SYSTEMS
In this curve the ordinates represent the per cent, of normal
dirt, i. e., the amount likely to be found in a dirty carpet, re-
maining in the carpet at any stage of the cleaning, and the
abscissae the number of strokes that have been made by the
sweeper. Heavy solid lines represent the results with the inrush
open and dotted lines the results with the inrush stopped. The
figures on the curve represent the degree to which the handle
has been varied from the position giving the best results in
cleaning.
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Number of StrolWft of Swt«|9«r
PIG. 21. TESTS BY MR. REEVE, USING TYPE C RENOVATOR.
Fig. 22 shows the results of tests by Mr. Reeve using a reno-
vator of Type D, having a double cleaning slot, and indicate
that this type of cleaner is not as efficient as Type A and is
affected more by the canting of the handle from the best
angle for cleaning.
The above mentioned tests are published through the courtesy
of Messrs. Ewing and E wing, attorneys for the Vacuum Clean-
er Company.
Since the method of making these tests is entirely different
from that used by the author, a comparison of the results, with
any assurance that the same conditions existed in both cases, is
impossible. It occurred to the author that a comparison of the
results of the tests by Mr. Reeve, using a carpet artificially
filled with actual dirt taken from carpets, with the tests made
by the author on carpets naturally soiled, would tend to show
if equal results could be obtained by a vacuum cleaner by
artificially soiling a carpet with dirt taken from another car-
pet, and in cleaning a carpet naturally soiled.
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THE CARPET RENOVATOR
47
The author has reduced these results to the same units of
time per square yard of carpet cleaned as in the test on the
Philadelphia carpet with the small-sized Type A renovator
(11-in. X yz-in. face and 10-in. x 3/16-in. cleaning slot). The
carpet used by the author contained 6 sq. yds. and was held
in cleaning by a weight at each corner, while the carpet used
by Mr. Reeve was ^ yd. wide and cleaned for approximately
one yard of its length, the relative size being 1 to 8. The time
of cleaning was 6 min. in the author's test which would corre-
h
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Num bcr of strokes
of Sweeper
PIG. 22. TESTS BY MR. RBEVE, USING TYPE D RENOVATOR.
i^pond to ^-min. cleaning in Mr. Reeve's test, or 30 strokes of
the sweeper. The total dust in the carpet in Mr. Reeve's test
was 5/40 lbs., or 2.66 oz. per square yard, and his test is
compared with the author's test with the carpet containing 2
»oz. per square yard. Calculation of the per cent, of total
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48
VACUUM CLEANING SYSTEMS
dirt removed in each 5 strokes of the sweeper in Mr. Eeeve's
test, and a comparison of the per cent, of dirt removed in each
one minute's test by the author are given below:
TABLE 4.
Comparison of Tests Made by Mr. Reeve and by the Author.
Mr. Ree\t's Test.
Author's Test.
Material removed.
Material removed.
Strokes
per cent, of total.
Minutes.
per cent, of total.
5
62
1
6P
10
80
2
81
IS
89
3
90
20
94
4
95
25
97
5
98
30
99
6
100
The above comparison was made using curve A, Fig. 20,
with the sweeper at its best angle with the floor. The close
agreement of the two tests indicates that a carpet artificially
soiled with dirt actually removed from another carpet by a
vacuum cleaner is as difficult to remove as dirt which has been
worked into a carpet by ordinary daily use. This condition
does not result when any other substance is used to artificially
soil the carpet, as will readily be seen by reference to the tests
of carpets filled with sand and other substances which have
been described in this chapter.
A comparative test of three different renovators was recently
made by the author. Renovator No. 1 had a cleaning slot
14 in. long by ^ in. wide, the edges of the slot being a seg-
ment of a circle having a J^-in. radius. This form of cleaning
surface allows very small area of contact with the surface
cleaned and permits the admission of large air volumes, about
56 cu. ft., with 2-in. vacuum. It is practically a Type F reno-
vator, similar to that .used in the tests at Hartford.
Renovator No. 2 had a cleaning slot 9>4 in. long and J4 ^^
wide, the face of the renovator being approximately % in.
wide and practically a plain surface, a typical Type B reno-
vator.
Renovator No. 3 had a cleaning slot 7j4 in. long and % in.
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THE CARPET RENOVATOR 49
wide, the face of the renovator being }i in. wide and the
edges slightly rounded, a typical Type A renovator.
The carpet used was a Colonial velvet rug with J/^-in. nap,
closely woven, containing 6 sq. yds. This rug was filled with
12 oz. of dirt taken from separators of cleaning machines,
from which the lint and litter had been screened. This was
rubbed into the carpet until no dirt was visible on the surface,
the surface being then lightly swept with a brush and weighed.
In cleaning this carpet the renovator was passed once over
the entire surface at the rate of about 70 ft. per minute. This
required six strokes and 50 seconds for No. 1 cleaner, nine
strokes and 77 seconds for No. 2 cleaner, and 12 strokes and
100 seconds for No. 3 cleaner.
The carpet was then weighed, spread down and gone over
three times, weighed, spread down and gone over four times.
This operation was repeated until the carpet came within }^ oz.
of its weight when received.
Each of the three renovators was operated with a vacuum
of 2 in. at the renovator.
The results of these tests are illustrated by curves lA, 2A and
3A in Fig. 23. This shows that to remove 95% of the dirt
the renovator had to be passed over the carpet 20 times for
No. 1 renovator, 15 times for No. 2 renovator and 8 times for
No. 3 renovator.
Similar tests were then made with each of the renovators,
with a vacuum of 4.5 in. of mercury at the renovator. The
results are shown by curves IB, 2B and 3B (Fig. 23) These
show that to remove 95% of the dirt the renovator had to be
passed over the carpet 11 times with No. 1 renovator, 6}^ times
with No. 2, and 4J/2 times with No. 3.
These tests are all on the same carpet, with the same quan-
tity of the same dirt and with the renovators moved at the
same speed in each case. The comparison of the results should
give a fair indication of the efficiency of the different types
of renovators at different degrees of vacuum within the reno-
vator and, therefore, form the most conclusive proof of the
statements relative to the efficiency of renovators as given in
this chapter.
All cleaning tests that the author has observed indicate that
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50
VACUUM CLEANING SYSTEMS
the higher the vacuum within the renovator the more rapid
and effective the cleaning, and that the efficiency of the reno-
vator is fully as high with a small as with a large volume of
air passing through the renovator and with the same degree of
vacuum within same. Therefore, the most effective and eco-
100
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90
80
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30
20
10
50
2 4 G 8 10 . 12 rt 16 18
Timc5 Over
FIG. 23. TESTS SHOWING EFFICIENCY OF DIFFERENT TYPES
OF RENOVATORS AT DIFFERENT DEGREES
OF VACUUM.
20
nomical renovator should be that which gives the highest
vacuum with the least air passing.
If the degree of vacuum within the renovator be carried to
an abnormally high degree, there will be a tendency for the
renovator to cling so close to the carpet that its operation will
be difficult and the wear on the carpet rapid. The produc-
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THE CARPET RENOVATOR
51
tion of this high vacuum, with a larger quantity of air ex-
hausted, will result in the expenditure of power at the reno-
vator in excess of the gain in efficiency and speed of cleaning*
It is evident that the wider the cleaning slot, the greater will
be the tendency of the renovator to stick to the carpet with a
high vacuum within the same. The author has experienced no
difficulty in operating the 10-in. renovator, with 3/16-in. clean-
ing slot, with a vacuum ss high as 9 in. of mercury, but wider-
slot renovators always push hard when any high degree of
vacuum exists within them.
Effort Necessary to Operate Various Types of Renovators.
— The author made a series of tests to determine the effort
necessary to operate the various types of renovators under dif-
ferent conditions. In making these tests the renovator was at-
tached to a spring balance and pulled along the floor, the pull
required to move the renovator being observed by the reading
of the balance. Three types of renovators were used in this
test: Type A, having a cleaning slot 5/16 in. wide and 12 in.
long; Type C, having a cleaning slot 5/16 in. wide and 12 in.
long, with an auxiliary inrush slot }i in. wide and 12 in. long ;
Type F, having a cleaning slot ^ in. wide and 10 in. long. The
results were as follows:
TABLE 5.
Effort Necessary to Operate Cleaning Tools.
Kind of Carpet.
Brussels, short
Napped, close back.
Axminster, long nap
Velvet, with glue
Sized back
Velvet, without glue.
Sized back...
Linoleum
Type of
Renovator.
Vacuum at Reno-
vator, In. Hg.
Pull,
Pounds.
8
3J4
20
17
11
3/2
14
8J/2
6K2
18
17
3/2
1
15
12
13
1
23
10
Air, cu. ft.
per min.
A
C
F
F
A
C
A
C
A
C
27
31
59
59
28
31
40
45
12H
40
It may be noted that, when operating on the Brussels and
the glue-sized velvet, the pull required to move all types of
renovators bears a direct ratio to the degree of vacuum under
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52 VACUUM CLEANING SYSTEMS
the renovator, and that the quantity of air exhausted is the
same for each renovator on either carpet, but different for each
type of renovator. It is evident that, in this case, very little
air enters the renovator by passing up through the carpet, and
hence the action of the inrush slot on Type C renovator is
noticeable only to a slight degree. When operating on velvet
carpet, without glue-sized back, the inrush slot, in conjunc-
tion with the greater quantity of air coming through the car-
pet, has caused the passage of a large quantity of air, while
the vacuum maintained at the renovator is greatly reduced
over that which was maintained under Type A renovator when
the same quantity of air was passing. In this case, nearly all
of the air entering Type A renovator came from the under
side of the carpet. The effect on the efficiency of cleaning with
Type C renovator under these conditions can readily be imag-
ined, by reference to former tests, as being greatly reduced
over that of Type A when passing the same quantity of air.
With linoleum, the action of the inrush slot of the Type C
renovator has again greatly redueed the vacuum under the
renovator, although the quantity of air is much in excess of
that passing Type A renovator. The difference in the behavior
of the renovators on different makes of carpet is seen to be
due largely to the difference in the quantity of air which passes
up through the carpet into the renovator.
It is evident that, with the same degree of vacuum within
the renovator, all types are equally easy to push and that, if
the vacuum within the renovator becomes higher than is nec-
essary to produce good cleaning results, unnecessary effort will
be required to operate the renovator.
Relative Damage to Carpets with Various Types of Reno-
vators. — ^A few tests have been made by the author to deter-
mine the relative damage to carpets with the various types of
renovators in use and it is found that, when the edges, of the
renovators are made exceedingly sharp, considerable nap. is
pulled out. However, if the edges are made slightly rounding
and not too narrow, no undue wear will occur with any of the
types *of renovators described, provided the vacuum in the
renovator is not permitted to become greater than 5 in. of
mercury.
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THE CARPET RENOVATOR 53
The author considers that for best results the vacuum should
not be less than 3J^ in. of mercury at the renovator and that
at least 2 in. is necessary to do even fair work, while, to per-
mit easy operation and prevent undue wear on the carpets, it
should not be higher than 5 in.
Before deciding which type of renovator will be most eco-
nomical to use in any case the character of the cleaning to be
done must be considered.
Of the various types of renovators considered in this chapter,
Type C can be dismissed at once, as it is neither as effective
a dust remover as Types A or F nor will it remove litter any
more effectively than Type F. Tests of Type D renovator do
not show as good results as a dust remover as Type A^ nor
will it remove litter any more effectively. Type E renovator
is a modification of Type C and is not likely to be any better.
The selection, therefore, lies between Type A and Type F
renovators, the former being by far the best dust remover,
while the latter will pick up a limited amount of small litter,
such as matches, cigar and cigarette stumps, and small bits of
paper. Where large quantities of these articles are likely to
be encountered, it is more important that the renovator should
be capable of picking them up, but, unfortunately, when these
articles are met with, there are also likely to be much larger
articles present that cannot be picked up by any but a specially-
designed renovator, and other means must be employed to
remove them.
In residences, private offices and nearly every place where
carpets or rugs are likely to be used, waste baskets and cuspidors
are provided and the articles mentioned are deposited in them
rather than on the floor. Thus, the renovator will be required
to remove dust, cigar ashes and sand or mud only, all of which
can be readily removed with a Type A renovator with less ex-
penditure of power than with a Type F renovator.
Public places, such as ante-rooms, reception rooms and other
offices to which the general public is admitted in great num-
bers and which are sometimes carpeted, are likely to contain
articles which can be picked up by Type F renovator and not
by Type A. For cleaning such places, a Type F renovator is
necessary, although it requires considerably more power, but
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54 VACUUM CLEANING SYSTEMS
the author sees no reason why this type of renovator should be
used to the exclusion of Type A, even in buildings containing
rooms of this character. If the building also contains several
rooms where litter will not be encountered, the author would
recommend that both types of renovators be used, each in its
proper place, and thereby cause a considerable saving of power
in cleaning rooms where no litter is encountered.
For residence work there is little need of providing carpet
renovators capable of picking up litter and, also, there wiU be
very little bare floor cleaning to be done, which requires larger
volumes of air. A smaller capacity exhausting plant, there-
fore, can be installed, if the Type A renovator is adopted.
In large office buildings where all cleaning is done after office
hours, where the building is provided with its own power plant,
and where speed of cleaning and ability to clean all apartments
with the fewest tools to be carried by the cleaners is desired,
it appears to be better to use only Type F renovators for all
carpet work, as the extra power required will not be of vital
importance.
Summing up the matter, the author believes that both Type
A and F renovators have their uses in their proper places but
that Type A has the widest field of usefulness, yet it need not-
invade the field of the other. He also believes that this fact
will be realized by manufacturers in the near future, when the
two types of renovators will work tbgether side by side for the
general good of the manufacturers and the users.
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CHAPTER IV.
Other Renovators.
The renovator which is -next in importance to the carpet
renovator is that nsed for cleaning bare floors. The earliest
form of this renovator was the oscillating floor type intro-
duced by Mr. Kenney. This was a modification of the narrow-
slot carpet renovator introduced by him. The body of same
was curved and supported on two small wheels or rollers, with
the intention of bringing the cleaning slot close to the surface
cleaned without its touching same, as indicated in Fig. 24.
This form of renovator was found to be impracticable for
the reason that any change in the angle with which the stem
or tube connecting the body of the renovator with the handle
in relation to the surface cleaned tended to make its action
FIG. 24. EARLY TYPE OP BARE PIG. 25. LATER TYPE OP BARE
FLOOR RENOVATOR. FLOOR RENOVATOR.
ineffective. If the angle were made less the distance between
the cleaning slot and the floor was increased, allowing the air
to enter the cleaning slot without coming in contact with the
surface to be cleaned, or, if the angle were made greater, it
would cause the face of the renovator to strike and damage
the surface of the floor.
The wheels or rollers on which this renovator was mounted,
55
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VACUUM CLEANING SYSTEMS
being so small, were subject to rapid wear both on their faces
and in their bearings, and when these wheels were slightly worn
the renovator was practically useless. On account of the above
defects this form of renovator was abandoned shortly after its
introduction.
The next form of renovator to be tried was a modification
of the ordinary soft bristle brush, such as had been in general
use for cleaning hard wood floors. The bristles were arranged
around the edges of the cleaning slot, in the body, which was
shaped similar to the slot in the carpet renovator. Rubber or
leather curtains or skirting, extending nearly to the ends of
the bristles, was placed inside of these bristles in order to cause
the air in entering the body of the renovator to come into
intimate contact with the surface to be cleaned. The general
form of this type is shown in Fig. 25.
FIG. 26. ANOTHER TYPE OF BARB FLOOR RENOVATOR.
This form of renovator, while more efficient than the oscil-
lating floor type, still had its faults in that it had a ten-
dency to push the dirt along the floor in front of it, much
the same as the floor brush from which it was copied was
designed to do. Also, there was too much tendency for the air
to pass into the body of the renovator without coming into inti-
mate contact with the surface to be cleaned. While this type
of floor renovator or a slight modification thereof is still in
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OTHER RENOVATORS 57
use by several manufacturers today, it never has and never will
be an effective bare floor cleaner.
A modification of this type of bare floor renovator, in which
the bristles have been shortened and made thicker, the skirting
or flaps placed on the outside and the stem provided with a
swivel joint, is shown in Fig. 26. Such an arrangement is
an improvement over the former type as, owing to its wider
and shorter mass of bristles, there is less tendency for the air
to pass into the body of the renovator without coming into inti-
mate contact with the surface cleaned. It is still prone to push
its dirt before it and is far from being a perfect bare floor
cleaner.
The next modification in the bare floor renovator was the
abandoning of the bristle brush in favor of a cleaning surface
composed of felt as shown in Fig. 27. In this form of reno-
PIG. 27. BARB FLOOR RENOVATOR WITH FELT CLEANING
SURFACE.
vator the air entering the body of the same must pass either
between the felt and the surface cleaned or through the felt
itself, and this air quantity is small. Since this renovator
has a wider cleaning slot than the Type A carpet renovator,
and, as it is used with the same vacuum producer, hose and
pipe lines, a considerable degree of vacuum will be produced
under same, especially when operated on polished floors, where
the conditions are nearly the same as we observed with Type
A carpet renovator operated on linoleum. With the wider
slot, the effort to move these renovators becomes too great for
easy operation. This trouble can be overcome by using a soft
grade of felt which permits sufiicieht air to pass through its
open pores to reduce the vacuum under same and permit easy
operation. Unfortunately, this felt is subject to rapid wear
when operated on surfaces as hard as floors and its use has
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VACUUM CLEANING SYSTEMS
been abandoned in favor of a harder felt. Openings are left
in the felt to permit the passage of sufficient air to reduce the
vacuum in the renovator to working limits. These slots have
taken many forms. In one form the felt was placed in alternate
X and diamond shapes, glued to the face with small open spaces
between them, as illustrated in Pig. 28. However, as these
^iC^^>:«^^^^^^gm
^^'imi'^!i^^.-k
FIG. 28. BARB FLOOR RENOVATOR WITH UNUSUAL FORM
OF SLOT.
small pieces must be held in place by glue, they are easily
broken loose and the efficiency of the renovator impaired.
Another method, which has now become standard, is to open
the ends of the renovator sufficiently to permit easy operation.
This method produces high velocities at these end openings
which are very effective in cleaning close to walls and in cor-
ners, where large quantities of dust always lodge and are re-
moved with difficulty without these open slots.
The wear on these felt faced renovators was found to be so
rapid that hard felt or composition rubber strips, placed so
that the wear comes on the edges of the same, have been sub-
stituted. The felt or rubber was screwed on to the outside of
a metal shell and projected sufficiently below the face of the
metal to permit considerable wearing off of same before the
FIG.
29. BARE FLOOR RENOVATOR WITH HARD FELT OR
COMPOSITION RUBBER STRIPS.
surface of the metal came in contact with the surface cleaned.
When this occurs, the felt strips can readily be replaced with
new ones. The ends are left open about ^4 in. to form an
inrush for the entering air. Such a type is shown in Pig. 29.
This renovator, in either of the above-described forms, is a
great improvement over the bristle brush in that the air passing
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OTHER RENOVATORS 59
into the body of the renovator must come into intimate contact
with the surfaces cleaned, but it still has the disadvantage of
tending to push the dirt before it.
A modification of the above-described renovators has been
introduced, in which the wearing surface of the renovator,
which is covered with felt, is rounded as shown in Fig. 30.
With this form of bare floor renovator, the air passing into
same is not only brought into intimate contact with the sur-
face cleaned but the dust is also crowded under the curved
surface of the renovator as the same is pushed over the floor
and thus brought directly into the path of the air current.
The last named type is by far the most effective for clean-
ing either polished or unpolished floors. It must be provided,
however, with inrush slots in order to prevent its sticking and
preventing easy operation. When operated with hose pipe and
PIG. 30. BARE FLOOR RENOVATOR WITH ROUNDED WEARING
SURFACE.
a vacuum producer necessary to produce 2 in. of vacuum in
Type A carpet renovators, at least 30 cu. ft. of air must be
permitted to pass the renovator. When operated with systems
adapted to produce 43/2 in. of vacuum in Type A carpet reno-
vators, at least 70 cu. ft. of air must pass the renovator in
order to permit easy operation.
This increase in the air quantity without change in the de-
gree of vacuum in the case of these renovators, is not without
increase in efficiency, as in the case of the carpet renovators,
because large quantities of dust and also small litter are met
with much more frequently on bare floors than on carpets.
With the increase in the volume of air passing^, it is possible
to pick up much heavier articles than with the smaller qu€Ln-
tity. It is also possible to pull dust out of deep cracks or
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60 VACUUM CLEANING SYSTEMS
from surfaces which are not in contact with the renovator face,
such as the spaces between the slats of floors of trolley cars.
This would not be possible with the small air quantity. The
use of the larger quantity of air prohibits the use of small-
sized hose and pipe and, therefore, larger articles can be con-
veyed through them. Where a large amount of bare floor must
be rapidly cleaned the use of the larger air quantity is recom-
mended.
A renovator (Pig. 30a) of unusual interest has recently been
developed by The United Electric Company, known as the Tuec
school tool. This is a bare floor tool open at both ends. It is
made telescopic and is mounted on three wheels fitted with
spring-actuated guide rails which are adjustable to the exact
distance between the legs of school desks. A turbine motor,
operated by the air passing through the renovator, is arranged
to drive two of the wheels by means of worm gear and clutch.
In operation the tool is placed opposite the front of a row
of desks. The clutch engaged on the turbine propels the tool
through the space between the desk legs to the rear of the
room. When the tool strikes the wall at the rear of the room,
the clutch is disengaged and it is pulled back by drawing in the
hose. The spring-actuated guides cause the cleaning slot to
lengthen when passing between the desk legs thereby cleaning
these spaces. The tool is then sent up the aisle, the wheels
being set so that it hugs the left side of the aisle when going
up and the right side when pulled back. The use of this form
of tool should result in considerable saving of time in cleaning
school rooms. Unfortunately, it cannot be operated where
pedestal stools are used.
For use in cleaning walls, ceilings, and other flat surfaces of
similar character, the bristle brush is practically the only form
of renovator used.
Rubber skirting cannot be used on these brushes as it is too
harsh for the easily-marred surfaces encountered by this reno-
vator, and cotton flannel or a very soft grade of felt takes the
place thereof. This change in the material used for skirting
results in a greater short-circuiting of the air into the cleaner
without coming into intimate contact with the surface cleaned
than occurs when used with rubber or hard felt on bare floors.
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OTHER RENOVATORS 61
As the material to be removed from surfaces of this char-
acter is very light dust, which has simply settled on the surface
and is not ground in, it is very easy to dislodge. When a
bristle brush, with a small volume of air passing through same,
is used to remove this material, a greater portion thereof is
pushed off the projections and other points of lodgment and
falls to the floor from whence it must be removed by a second
operation, using a floor renovator. In fact, the use of an ordinary
bristle brush, followed by the use of a floor renovator, will
give almost as good results as the use of a bristle wall brush
with a small quantity of air passing. However, with a large
quantity of air passing into the renovator, this light surface
dust will all be picked up by the rapidly-moving air current and
effective cleaning can be accomplished without the renovator
coming into direct contact with the surface to be cleaned.
The author considers that a different form of renovator is
necessary to effectively clean walls, ceilings and similar flat
surfaces, with a small quantity of air passing and would recom-
mend the use of some form of renovator having a cleaning face
composed of cotton flannel or some other soft substance which
could be moved over the surface cleaned, in intimate contact
therewith and without damage thereto. With the soft, open
fibre of the substance necessary to be used as a working surface,
suflScient air would enter the renovator without resorting to the
use of inrush slots or openings and much better results would
be obtained. No such renovator has been designed for this
purpose to date, for what reason the author does not know,
and until some such renovator is produced a large volume of
air will be necessary for cleaning this kind of surfaces.
An illustration of this defect in the wall brush was brought
to the author's attention recently in watching a gang of labor-
ers cleaning the walls in the U. S. Treasury Building. They
had at their disposal a portable cleaner of the most efficient
type, but in lieu of using the wall brush provided with same,
they were rubbing off the walls with a cloth mop which had
been soaked in oil, then air-dried, known as the **dustless
duster." This was mounted on the end of a pole. The work-
men frequently cleaned this duster with the vacuum cleaner
hose without any renovator attached thereto. This cleaner.
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VACUUM CLEANING SYSTEMS
with brush in use, passed approximately 30 cu. ft. of free
air per minute. It is evident that these laborers had learned
by experience that it was practically useless to try to remove
dust from the walls by the direct application of the wall brush
to surfaces and were undoubtedly accomplishing much better
results in the roundabout way they had of necessity adopted.
When carved or other relief work is encountered, the round
bristle brush, with extra long bristles and cotton flannel skirt-
ing, is nearly universally used. This type of renovator is
shown in Fig. 31.
FIG. 30a. THE TUEC SCHOOL TOOL.
PIG. 31. ROUND
BRISTLE BRUSH
FOR CARVED OR
OTHER RELIEF
WORK.
Owing to the irregularity of such surfaces, intimate contact
therewith cannot be obtained and practically no results will be
had unless there is a large quantity of air passing through
the renovator. When a large quantity of air is available,
nearly as good results in cleaning this character of sur-
FIG. 32.
RUBBER-TIPPED CORNER CLEANER FOR USE ON
CARVED OR OTHER RELIEF WORK.
face can be obtained by the use of. the straight rubber-tipped
comer cleaner, with a round opening about ^ in. in diameter,
as illustrated in Fig. 32. A very high velocity will be obtained
through this renovator which will pull the dust out of inac-
cessible places. This form of cleaner is also very effective for
cleaning the corners of rooms, where the floor and walls inter^
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OTHER RENOVATORS 63
sect, veritable dust catchers that they are, the cleaning of which
is fully as important as it is difficult. Pigeon holes and other
small compartments in safes, desks and similar furniture can
be easily cleaned with this little renovator by simply introduc-
ing it into the front of such compartment.
To be effective, this renovator must pass approximately 55
cu. ft. of air per minute and will require a vacuum within the
renovator of approximately S}^ in. of mercury. Where only
a small quantity of air is available, the author considers that
it is better to make use of compressed air to blow the dust out
of relief work, pigeon holes, and other inaccessible places and
subsequently pick this dust up with other forms of renovators
after it has found lodgment at more accessible points.
The cleaner which has met with the most disastrous results
to the surfaces cleaned is the furniture or upholstery renovator.
This has nearly always taken the form of a small carpet reno-
vator. The type of upholstery renovator used for many years
by the Sanitary Devices Manufacturing Company is illustrated
in Fig. 33. This renovator had an inrush slot in the center.
PIG. 33. EARLY TYPE CP UPHOLSTERY RENOVATOR.
separated from a cleaning slot on each side by a partition ex-
tending to within 1/32 in. of the working face of the reno-
vator. It had the hose connected into one end which was ex-
tended to form a handle. With this cleaning tool it was
considered impossible to obtain a high vacuum within the reno-
vator, as the inrush slots were supposed to act as vacuum
breakers. However, as the surface of the upholstery is not
firmly attached to the furniture it could be drawn up into the
cleaner, closing the space under the partitions and permitting
a high vacuum to be obtained. This caused the renovator to
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64 VACUUM CLEANING SYSTEMS
stick, but, owing to the narrow slot on each side of the inrush,
the fabric was not caught.
Other manufacturers used a renovator with a single slot, in
0ome cases as wide as ^ in., and instances are on record where
the coverings of the furniture have been drawn up through the
cleaning slot into the renovator and wedged so tightly that it
was necessary to cut the covering from the furniture in. order
to release the renovator. To overcome this difl&culty one manu-
facturer constructed the renovator in two pieces, secured to-
gether with screws, so that, in case the renovator became caught,
it could be taken apart to release the fabric.
Many manufacturers have attempted to overcome this de-
structive tendency of the straight-slot upholstery renovator by
inserting partitions on the cleaning face of the renovator, thus
dividing the cleaning slot into a number of small slots the area
of each not being suiBciently large to permit the drawing in of
the fabric. These cleaners have followed two general forms,
one having narrow slots running lengthwise of the cleaner, as
illustrated in Fig. 34. This form reduces the destructive ten-
^:/V(? Cteanlncf here
PIG. 34. UPHOLSTERY RENOVATOR WITH NARROW SLOTS TO
PREVENT DAMAGE TO FURNITURE.
dency to a great extent, but does not entirely prevent drawing
the fabric into the renovator. If the partitions across the reno-
vator be continuous, as indicated by the sketch, there will be
a portion of the renovator which will not do any cleaning.
Another form uses short slots, sufficiently inclined for the top
of one slot to overlap the bottom of its neighbor, as shown in
Fig 35. This form of renovator is effective throughout its
entire length and the small area of each slot makes it practically
impossible to draw the fabric into the cleaning slot. It is con-
sidered by the author to be superior to the former type,
especially when cleaning lace curtains or silk hangings or any
other very light fabric.
• However, if the exhauster be of such characteristics and the
hose and pipe lines be so proportioned that there is practically
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OTHER RENOVATORS 65
a constant vacuum in the renovator, regardless of the quantity
of air passing, and provided this vacuum is not allowed to ex-
ceed 5 or 6 in. of mercury, no disastrous effects will be ex-
perienced in cleaning light-weight fabrics with a straight-^lot
renovator having a cleaning slot not over J4 ^^' wide. The
use ef this type, in connection with a system having the above-
described characteristics, is recommended whenever rapid clean-
ing is desired.
Upholstery renovators make the most serviceable clothing
cleaners, while a small type of bristle brush, not over 4 in. long
and not over ^ in. wide, makes the most serviceable hat brush.
An important form of renovator is that used for cleaning be-
tween the sections and behind heating radiators. A piece of
PIG. 35. ANOTHER TYPE OF UPHOLSTERY RENOVATOR WITH
SHORT SLOTS.
tubing, flattened at its outer end, is by far the most effective
device for this purpose. This renovator, in connection with
the hat brush tool, makes the two best renovators for use in the
library, effective cleaning being possible with not more than
20 cu. ft. of air per minute, but much faster work can be done
with larger quantities.
Another form of renovator sometimes furnished is the small
hand brush. This is a bristle brush, approximately 8 in. long
PIG. 36. HAND BRUSH TYPE OF RENOVATOR.
and 2 in. wide, with the hose connection made into one end of
same, as illustrated in Fig. 36. This renovator is useful for
cleaning wooden furniture, shelves, tables, and other^ horizontal
.surfaces at about hand height, but, owing to the; tendency of
the. air to short circuit in its way to the body of the renovator,
it will not do effective work with small quantities of air.
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66 VACUUM CLEANING SYSTEMS
Many manufacturers have produced a special renovator for
cleaning stairs. This has nearly always taken the form of a
bristle brush, approximately 4 in. square. When renovators
are rigidly attached to their stems, this form of renovator is
convenient and almost a necessity. However, when swivel joints
are provided, the ordinary carpet or bare floor renovators are
fully as convenient, and, being larger, are more rapid cleaners,
and the stair renovator is unnecessary.
In isolated cases, where unusual cleaning is necessary, such
as the removal of cork dust from the floors of a cork factory,
picking, up telegraph forms from the floors of stock exchanges,
pioking up wrapping papers in watch factories, etc., special
forms of renovators, with large openings and large capacities
for air exhaustion, become necessary. These appliances have
generally taken the form similar to the carpet renovator, but
with much wider slots, the forward edges of which are raised
slightly above the surface of the floor when the renovator is in
operation. These renovators, being of no use for any other
purpose than that for which they are specially designed, and
requiring quantities of air in excess of those usually provided
for ordinary types of renovators, may be considered simply as
special appliances and do not form a part of the outfit required
to be furnished with an ordinary cleaning system.
Another class of cleaning which requires a special system and
special appliances is the renovation of furs. Purs must never
be brushed, as it tends to mat the hair and produce an effect
opposite to renovation. The only agent suitable for renovating
furs is compressed air and the form of renovator best suited
for this work is a straight nozzle, flattened at the end with a
slot approximately 4 in. long and not over 1/32 in. wide, from
which the air escapes in a thin sheet. When held at such an
angle that the air will impinge on the skin under the hair, a
thorough renovation of the fur is possible.
For the renovation of pillows a hollow needle, with small
openings along its sides, supplied with compressed air, produces
the best results. The needle is thrust through the cover into
the mass of feathers, the air tending to loosen up the matted
feathers and to leave them in practically the same condition as
when the pillow was first filled.
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OTHER RENOVATORS 67
As the arrangement of the air removal system, to permit it
being reversed from exhaustion to compression, complicates the
outfit and adds to its first cost, and as cleaning of this char-
acter is required only at rare intervals, these renovators may
also be considered as special and need not be included in the
average equipment.
The author considers that the renovator equipment for a sys-
tem in which from 20 to 30 cu. ft. of air per minute is ex-
hausted for each renovator in operation, and which the author
classes as a ** small volume'' system, should contain the followr
ing renovators in each ''set" furnished:
One carpet renovator with cleaning slot }i in. by 12 in. long.
One bare floor renovator 12 in. long, with curved felt-
covered face.
One wall renovator 12 in. long, with cotton flannel and
curved face.
One upholstery renovator with slot %. in. by 4 in.
One comer cleaner.
One radiator cleaner.
In addition, one or more hat brushes should be included
with each installation.
The renovator equipment for a system in which 70 cu. ft.
of air per minute is exhausted for each renovator in operation,
which the author classes as a ** large volume" system, should
contain the following renovators in each **set" furnished:
One carpet renovator, with slot J4 ^^* by 15 in.
One bare floor renovator 15 in. long, with curved felt-cov-
ered face.
One wall brush, with skirted bristles 12 in. long and 2 in.
wide.
One hand brush, with hose connection at end, 8 in. long
and 2 in. wide.
One 4-in. round brush for relief work.
• One upholstery renovator.
One comer cleaner.
One radiator tool.
At least one hat brush with each system.
The number of sets of renovators to be furnished should
naturally be at least equal to the number of sweepers which
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6S VACUUM CLEANING SYSTEMS
the plant will handle, and in all buildings, except residences,
there should be one set of renovators for each floor of the
building. This will be ample, except in exceedingly large
buildings.
The wearing face of any renovator should never be made of
soft metal, such as brass or aluminum, as the action of the
dust passing the face of the renovator, where the velocity is
always the highest in the system, will roughen these parts
and cause undue wear on the surfaces cleaned. Stamped steel
is undoubtedly the best material for wearing surface and cast-
iron ranks next. These are the only materials which should
be permitted.
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CHAPTER V.
Stems and Handles.
Having discussed the various forms of renovators in detail,
the next appliance to be taken up is the connection between
the renovator and the cleaning hose, this being the next por-
tion of the apparatus forming a conduit for the dust-laden air
on its way from the renovator to the atmosphere on the exhaust
side of the vacuum producer.
In order that the renovator may be moved about on the
surfaces to be cleaned, a rigid handle must be provided and,
. in order that these various surfaces may be reached while the
operator remains in a standing position, it is necessary that
this handle be oi considerable, as well as variable, length. Also,
a passage for the dust-laden air must be provided in connection
with this handle. These conditions are best met by a metal
tube, which the author terms the stem.
These stems have been made of various metals, that first used
being drawn brass, probably because it is best suited to be
nickel plated. On the earlier systems they were almost in-
variably made of No. 16-gauge tubing, ^-in. outside diameter,
and were bent at their upper end through an angle of nearly
135° in order that the hose would hang from the stem vertically
downward, when the stem was held at an angle with the floor
of 45°.
The lower ends of these stems were rigidly attached to the
renovator in such a manner as to assume the above-mentioned
angle with the floor when the renovator was in the proper
position for cleaning. In order to bring the curved portion of
the stem hand high, the stem was made approximately 5 ft.
long.
When operated with Type A carpet renovators, these curved
stems were apparently satisfactory. However, when they were
used in department stores, and other places where much bare
69
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70 VACUUM CLEANING SYSTEMS
floor cleaning was necessary, the steins were cut through at
the curved portion by the sand blast action of the dust. The
cutting of these stems in bare floor work, while they were satis-
factory in carpet cleaning, indicates that the velocity in the
stem, due to the large volume of air passing the bare floor
renovator, was too great for this soft metal to withstand the
impact of the dust on the curved surface. With the systems
in use at that time no means were provided to control the
vacuum at the vacuum producer and the hose and pipe lines
were small, both of which tended to cause a wide variation in
the volume of air exhausted under various conditions, in
the character of surface cleaned, and in the number of reno-
vators in use. Therefore, the value of this destructive velocity
is not readily obtainable. However, the author considers that,
in extreme cases, the quantity of air passing through these
stems may have been as high as 55 cu. ft. per minute. As the
inside diameter of the stems was ^ in. the area was 0.44 sq. in.,
or 0.00328 sq. ft., and the velocity through the stem was nearly
17,000 ft. per minute. With an average air passage of 40 cu.
ft. per minute the velocity was 12,200 ft. per minute.
Referring to tests of carpet renovators. Chapter III, it will
be noted that the maximum volume of air passing through
carpet renovators of Type A was 33 cu. ft. per minute, which
gives a velocity of 10,000 ft. per minute. Apparently, at this
velocity, the cutting action, due to the impact of the dust on
the curved surfaces, was not severe. However, the author con-
siders that the maximum velocity that should be permitted
through these stems is 9,000 ft. per minute.
As the dirt picked up must be lifted almost vertically, the
velocity in the stem must not become too low or dirt will lodge
in the stem. Experiments made by the author indicate that
the minimum velocity should be at least 4,000 ft. per minute,
in order to insure a clean stem at all times.
Shortly after the introduction of vacuum cleaning, the use
of drawn-steel tubing for the manufacture of stems for clean-
ing tools was standard with one manufacturer and, lately, its
use has become almost universal, except in cases where very
long stems are necessary, as on wall brushes when cleaning
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STEMS AND HANDLES 71
very high ceilings. For such work, aluminum stems have been
adopted.
This harder metal will better withstand the cutting action
of the dust and can also be made much thinner and lighter in
weight than brass tubing of equal strength. These stems were
made from 1 in. outside diameter, No. 21 gauge tubing, having
an internal area of 0.68 sq. in., and the author does not know
of any cases where these stems have been cut by the impact
of the dust.
Stems of this metal are recommended by the author for use
with all floor renovators and with wall brushes, except in
cases where exceedingly long stems are required, when those
of drawn aluminum tubing are recommended.
For use with Type A renovators, where the minimum air
quantity is approximately 22 cu. ft. per minute, the greatest
area permissible is ^^l^ = 0.0055 sq. ft., or 0.79 sq. in., equiva-
lent to 1-in. diameter. With a maximum air quantity, under
proper control, of 39 cu. ft. per minute, the minimum area
will be irHir = 0.00433 sq. ft. or 0.625 sq. in., equivalent to
0.89 in. diameter, so that a 1-in. outside diameter stem of No.
21 gauge metal, having an inside diameter of 0.932 in., is
recommended.
For use with a Type P renovator, with a minimum air quan-
tity of 44 cu. ft. per minute, the maximum area of the stem
will be zHiy = 0.011 sq. ft., or 1.58 sq. in., equivalent to 1.4
in. diameter, while, with a maximum air quantity of 70 cu. ft
per minute, the minimum area will be -g^-^ =0.0077 sq. ft,
or 1.11 sq. in., equivalent to 1.18 in. diameter, and a lj4-i^-
diameter stem of No. 21 gauge metal, having an inside diam-
eter of 1.18 in. is recommended.
Tests of Mr. S. A. Reeve, which are discussed in Chapter
III, indicate that both edges of the cleaning sibt on any reno-
vator must be in contact with the surface cleaned in order to
do effective cleaning. A renovator which is rigidly connected
to its stem can be effectively operated with the stem at but
one angle with the surface cleaned, which makes the cleaning
under furniture, or on waU at various heights above the floor,
impossible. In order to do effective cleaning with any degree
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VACUUM CLEANING SYSTEMS
of speed and comfort to the operator, some form of swivel joint
between the renovator and its stem is necessary.
These swivels have been made in many forms, one of which
consists of two hemispheres connected by a bolt on their axis,
as shown in Fig. 37. This form of swivel is unsuited for use
under these conditions, as lint, thread and any other small
articles picked up will catch on the bolt which lies directly
in the path of the dust-laden air current, and its use should
be prohibited in all cases.
Another form of swivel, which is must better than the last
mentioned, is shown in the illustration of the bare floor brush,
Fig. 26, Chapter IV, there being no obstruction in the air
passage. However, these swivels are composed of moving parts
FIG. 37.
FORM OF SWIVEL. JOINT CONNECTING STEM TO
RENOVATOR.
which are in contact with the dust-laden air and great care
must be taken in their design so that in action dust does not
lodge between the wearing surfaces and shortly ruin the swivel.
This can be guarded against by making any opening between
the parts of the swivel point away from the dust current, as
indicated in Fig. 38, in which the direction of the air current
is indicated by the arrow. A slightly loose fit between the
wearing surfaces will permit a small leakage of air through the
joint which will tend to remove any dust which may find its
way into the joint However, it is not considered advisable
either to allow very much leakage through the joint, as it re-
duces the net efl&ciency of the system, or to depend much on
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STEMS AND HANDLES 73
the air current through the joint keeping the wearing sur-
faces clean. The swivel indicated in the illustration of the
floor brush does not entirely prevent the dust entering same
and it permits the movement of the stem in a vertical plane
only. On the other hand, a swivel consisting of a 45° elbow,
rigidly attached to the stem and turning f reelj'' on a horizontal
spud, and fastened to the renovator, as shown in Fig. 38, allows
a motion of the stem either in a vertical plane, which will cause
the renovator to rotate, and enable the operator to pass same
around or back of legs of furniture, or a semi-rotary motion
may be imparted to the stem, which will permit the renovator
PIG. 38. SWIVEL JOINT ARRANGED TO PREVENT DUST LODGING
BETWEEN THE WEARING SURFACES.
to move forward in a straight line while the angle which the
stem makes with the floor will constantly decrease. After a
little practice the operator can place a renovator equipped with
one of these swivels in almost any position without incon-
venience. Illustrations of the possibilities of this form of
swivel are presented in Figs. 39 and 40, in which an operator is
shown cleaning the treads and risers of a stairway without
changing her position, and in Fig. 41, where the operator is
cleaning the trim of a door with apparent ease. The author
considers that this form of swivel is the only satisfactory joint
between the renovator and its stem. It is being rapidly
adopted by nearly every manufacturer of vacuum cleaners.
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74 VACUUM CLEANING SYSTEMS
In operating any renovator it is nearly always drawn back-
wards and forwards in front of the operator, across the surface
to be cleaned. When the hose is rigidly attached to the upper
end of the stem, it becomes necessary to drag at least a por-
tion of the cleaning hose along with the renovator when it is
moved forward, and to crowd the same back on itself when
the renovator is moved backward. This action has a tendency
PIG. 39. SWIVEL JOINT IN USB.
to kink or snarl the hose about itself and makes the operation
of the renovator very awkward, often causing the operator's
feet to become entangled in the hose.
This action also brings an undue amount of wear on the
hose near the end which is attached to the stem, as may be
readily noted by inspection of hose used with rigidly-attached
stems. This will show that the end of the hose is entirely worn
through, while the remainder of the hose is still in serviceable
condition.
The trouble above stated can be overcome by providing a
swivel joint at the point of connection between the hose and
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STEMS AND HANDLES 75
the stem. A few attempts to use a joint similar to that first
described in connection with the renovator and its stem, as
illustrated in Fig. 37, have been made, but without much suc-
cess, as the bolt through the air passage catches dirt and there
is not sufficient freedom of movement between the portions of
the swivel. Variations of this form of joint have been made,
one of which is provided with a screwed union to join the two
PIG. 40. ANOTHER USE OF SWIVEL JOINT, SHOWING POSSI-
BILITIES OF THIS FORM.
portions, as shown in Fig. 42. This is a much better form than
that first described and has been successfully used in connec-
tion with heavy 1-in. diameter hose. Care must be exercised
that the direction of the flow of air is always in the direction
indicated by the arrows in the sketches, as a reversal, if only
for a short time, will ruin the joint, due to lodgment of dust
in the moving parts.
Still another variation in this form of swivel has the two
main parts made to fit one within the other and a snap ring is
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76
VACUUM CLEANING SYSTEMS
placed in a groove in the male portion of the joint, this groove
being deep enough to take the entire thickness of the ring.
The two parts are then fitted together and the ring snaps out
into a corresponding groove in the female portion of the joint,
uniting the two parts. This joint gives a fairly free movement
PIG. 41. OPERATOR CLEANING TRIM OP DOOR WITH SWIVEL JOINT.
to the parts thereof, but has the disadvantage that it cannot be
taken apart without breaking one of its parts.
A modification of this form of swivel has been made by the
manufacturers of the last-described swivel, in which semi-
circular grooves have been cut, one on the inside of the female
PIG. 42, SWIVEL JOINT, WITH
SCREWED UNION.
PIG. 43.
SWIVEL JOINT HAVING
BALL BEARINGS.
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STEMS AND HANDLES 77
portion and one on the outside of the male portion. Steel balls
are forced into this groove, after the parts are assembled,
through an opening provided in the edges of the parts. This
opening is closed, after the balls are in place, by a small pin,
as shown in Fig. 43. The swivel then becomes a ball-bearing
PIG. 44. ACTON OF BALL-BEARING SWIVEL JOINT.
joint, with a freedom of motion characteristic of such bearings.
This joint readily responds to every movement of the stem and
keeps the hose hanging vertically downward and always free
from kinks. Its action is illustrated in Fig. 44, in which it
is being used in connection with a carpet renovator. This
joint is considered to be the most efficient on the market. It
is protected by a patent controlled by a manufacturer of
vacuum cleaners.
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78 VACUUM CLEANING SYSTEMS
Valves are placed at the upper end of the stems by many
manufacturers, to cut oflE the suction when carrying the reno-
vators from room to room, and when it is necessary to stop
sweeping to move furniture. These valves have nearly always
taken the form of a plug cock with tee or knurled handle. They
are useful on large installations, where vacuum control is either
inherent in the exhauster or where some means of vacuum con-
trol is provided, as a considerable saving of power may be
obtained by closing same, as will be explained in a later chap-
ter, and to overcome the unpleasant hissing noise caused by the
inrush of air into the renovator when same is held oflf the
floor.
When the exhauster has a capacity of but one sweeper and
when the cleaning is done at times when the building is unoc-
<;upied, there seems to be little need for this refinement, which
has two defects: first, the operators will not close the valves;
second, when they have been closed they are only partly opened,
as indicated in Fig. 45. When this occurs, the portions of the
FIG. 46. ILLUSTRATION OF DEFECTS OF PLUG COCKS.
plug, which are shown stippled, are quickly cut away by the
sand-blast action of the dust, making it necessary to open the
valve a still smaller amount the next time it is operated, cutting
oflf still more of the plug until a new plug is necessary in order
to make the valve again operative.
A few attempts have been made to overcome these defects
by making the valves self-closing and having them so con-
structed that when the operator grasps the handle the valve
will be forced wide open, on the principle of the pistol grip.
These valves will, of course, close whenever the handle is re-
leased, and it is impossible to grasp the handle in any degree
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STEMS AND HANDLES 79
of comfort without throwing the valve wide open. However,
since the valve is closed by a spring, considerable pressure must
be applied to the handle in order to keep it open and it acts
similar to the Sandow dumb bell in producing fatigue of the
fingers in a short time ; they have not come into general use.
The use of valves in the renovator handle is considered by the
author to be an expense not justified by the gain in economy
and they are no longer included in specifications prepared
by him.
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CHAPTER VI.
Hose.
The more important steps in the evolution of the modem
vacuum cleaning system can each be attributed to a change in
the design or construction of some one of its component parts,
which, in their former standard design, have acted as a limiting
factor governing the form and size of other and more im-
portant parts of the system.
That part of the early systems which played the most im-
portant role as a limiting factor was one for whose production
the builder of the system had to look to other manufacturers:
namely, the flexible hose connecting the renovator stem to the
rigid pipe lines and vacuum producer.
The early builders of vacuum cleaning systems naturally
adopted a standard article for use as a flexible conduit; that
is, the vacuum hose which had been used as suction lines for
pumps of various characters. For such use it was not necessary
that the hose be moved about to any great extent and, there-
fore, its weight was not an important factor and had been
sacrificed to strength to withstand collapse and the rough hand-
ling to which suction hose is subject.
This standard hose wias built up of many layers of canvas
wound around a rubber tube or lining. A spiral wire was im-
bedded between the layers of canvas to prevent collapse and
the whole was provided with an outer covering of rubber.
Generally five to seven layers of canvas were used and the
resulting hose was not highly flexible.
When used as a flexible conduit in connection with a vacuum
cleaning system it became necessary to constantly move the
hose back and forth and around the room to be cleaned. It was
also necessary to limit the weight of the hose to that which
could be easily handled by one person. This led to the adop-
tion of small sizes of the then standard hose, ^-in. diameter
being first used, but soon this was abandoned in favor of 1-in.
diameter hose weighing nearly 1 lb. per foot of length, which
is the maximum weight that can be conveniently handled by
80
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HOSE 81
one person. This size hose has become the standard for all
systems maintaining a vacuum at the separators of 10. in of
mercury or more.
Owing to its lack of flexibility this type of hose is easily
kinked and is damaged by the pulling out of such kinks, caus-
ing the tubing or lining to become separated from the canvas
and to collapse, rendering the hose useless. There is also con-
siderable wear at the point of connection to the stems of
renovators, where rigid connections are used.
The outside of this hose, being rubber, is always liberally
covered with soap-stone when it leaves the mianuf acturer, and
when new hose is dr*agged about over carpets, it frequently soils
same to a greater degrfee than tihey are cleaned by the reno-
vator. When this hose has been in use about twice as long
as is necessary to wear off the soap-stone, its appearance
becomes far from handsome and is not considered to be in
keeping with the nickel-plated appliances which are furnished
with the cleaning tools. To overcome this objection, an outer
braid has been applied generally over the rubber coating, thus
adding further to its already great weight.
AVhat was perhaps the first type of hose to be produced
especially for use with vacuum cleaning systems was that in
which the fabric was woven in layers, instead of being wrapped
spirally around the central tube or lining. Steam was intro-
duced into the lining, vulcanizing the lining and firmly uniting
the whole mass. This hose was made 1 in. in diameter, without
any metal re-inforcement, and was covered with the usual rub-
ber coating and with braid, when ordered. This hose weighed
12 oz. per lineal foot and 1-in. diameter was still the largest
that could be easily handled.
The first attempt to produce a light-weight hose for use
with vacuum cleaning systems was by covering a spiral steel
tape with canvas. The air leakage through this hose was found
to be so high that its use resulted in loss of efficiency of the
cleaning plant and it was found necessary to line the hose with
rubber. This rubber-lined hose is made in larger sizes than
formerly used and 2-in. diameter hose weighs approximately
14 oz. per lineal foot. It is also much more flexible than the
1-in. hose formerly used.
The introduction of this type made it possible to use larger
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82 VACUUM CLEANING SYSTEMS
hose in connection with vacuum cleaning systems and permitted
the use of a lower vacuum at the separators, with the same
results at the carpet renovator, and a larger quantity of air
when using the brushes and other renovators. Without this
type of hose the low-vacuum, large-volume systems would be
impractical.
Another type of hose has been recently introduced in which
a wire is woven into the fabric of the hose and the rubber
lining vulcanized into place as already described. No outer
coating of rubber is used and, therefore, no braid is necessary.
This gives a light-weight hose of great flexibility and neat ap-
pearance and is undoubtedly the best hose for residence work.
It is more costly than the steel tape hose which is recommended
for office building and factory use, where appearance is not
important.
Hose Couplings. — The earlier systems used couplings having
screw-threaded ground joints, similar to those which were then
in use on hose intended to withstand pressure. These couplings
FIG. 46. BAYONET TYPE OP HOSE COUPLING, INTRODUCED BY
THE AMERICAN AIR CLEANING COMPANY.
require considerable time to connect and disconnect and the
threads are easily damaged by dragging the hose about. The
exposed metal parts of the couplings are liable to scratch fur-
niture.
To overcome the time required to connect and disconnect the
screw-coupling, the American Air Cleaning Company intro-
duced the bayonet type of coupling, as iUustraited in Fig. 46.
This coupling is not readily damaged by rough handling, but it
has metal surfaces exposed which will scratch furniture.
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HOSE
83
Both of these couplings have the disadvantage that the
air current in the hose must always be in the same direction
and the same end of the hose must always be next to the
renovator handle. Both of these features tend to increase the
wear on the hose, and the reversal of the air current to re-
move stoppages is not possible.
The coupling produced by the Sanitary Devices Manufactur-
ing Company has a piece of steel tubing fitted into each end
of the hose and secured by means of a brass slip-coupler fitting
over the tubing. All ends being alike, the reversal of the hose
is possible with this form of coupling. However, the metal
coupler is liable to mar furniture and sometimes there is trouble
with the couplings pulling apart.
Much of the hose in use today is provided with **pure gum'*
ends are vulcanized in place, it is necessary to take the hose
of metal tubing is slipped inside of these ends to make a coup-
ling. With this arrangement there is no metal exposed to mar
FIG. 47.
ALL RUBBER HOSE COUPLING USED BY THE SPENCER
TURBINE CLEANER COMPANY.
furniture and the hose lengths are reversible. However, there
is some trouble from the couplings pulling apart. Since these
ends are vulcanized in place, it is necessary to take the hose
to a rubber repair shop whenever the hose breaks back of the
coupling, which occurs frequently when rigidly attached to the
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84 VACUUM CLEANING SYSTEMS
stem of the renovator. These repair shops are much more
numerous than a few years ago and this drawback is not a
serious one.
Another form of coupling used by the Spencer Turbine
Cleaner Company is the all-rubber male and female end, as
illustrated in Fig. 47. This has the advantage over the metal-
slip couplings and the coupling with pure gum ends in that
when it is properly locked it cannot be pulled apart. It is
absolutely air tight, which is true of no other coupling. But
it does not permit the reversal of the hose and is, therefore,
recommended for use only with hose of 1^4 -in. diameter or
larger, where there is less liability of stoppage, and where the
ball-bearing swivel is used at the connection to the stem, pre-
venting excessive wear at this point. The pure gum ends,
with the internal-slip coupler, is considered to be the most
satisfactory for use in all cases, except as above stated.
Hose Friction. — Hose friction plays an important part in the
action of any vacuum cleaning system. In fact, where 1-in.
hose is used, it becomes a limiting factor in the capacity of
the system to perform some kinds of cleaning.
There are several tables of hose friction published by the
manufacturers of vacuum cleaning systems, all of which appear
to have been based on a constant velocity within the hose equal
to that which would be obtained if the air were at atmospheric
pressure throughout the entire length of the hose. But in
practice the air is admitted to the hose from the renovator at
a considerably lower absolute pressure of from 25 in. to
27 in. of mercury, and is, therefore, moving at a higher
velocity. As the pressure is decreased by the friction loss in
the hose, the velocity constantly increases with the expansion
of the air.
The results of many tests made by the author during the
past seven years, with hose ranging from 1-in. to 2-in. diameter
and with an entering vacuum ranging from to 7 in. of mer-
cury and a friction loss of from 1 in. to 25 in. of mer-
cury, indicate a close agreement with the formula given in
Prof. William Kent's ''Mechanical Engineer's Pocketbook,"
which is based on the formula:
Q=c |/-
pdg
wL
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HOSE 85
Q = free air in cubic feet per minute.
c = a constant which was determined by D'Arcy as approxi-
mately 60.
p=the loss of pressure in pounds per square inch.
d = the diameter of pipe in inches.
L = the length of pipe in feet.
w = the density of the entering air in pounds per cubic foot
Reducing the pressure loss to inches of mercury and using
in lieu of w, r which is the ratio of the average absolute pres-
sure in the pipe to atmospheric pressure, this formula becomes :
Q=3io.3 /-H^
Lr
To permit the rapid calculation of the air quantity which
can be passed through a hose, the author has prepared the
diagram shown in Fig. 48. To use this table, look up the fric-
tion loss in the hose in the right hand margin, pass along the
horizontal line to the left until it intersects the line inclined
at an angle of 45'' toward the left, indicating the length of the
hose. From this intersection pass vertically to the line in-
clined at approximately 30** toward the left, representing the
diameter of the hose. The quantity in the left-hand margin,
opposite the horizontal passing through this intersection, repre-
sents the quantity, of air which would pass through this hose
in cubic feet at the average density in the hose. To correct this
quantity to free air, step oflf the distance on the vertical line
from the bottom of the table, representing the average degree
of vacuum in the hose, to its intersection with the curved
line near the bottom of table. Transfer this distance vertically
downward on the left hand margin from the quantity first
read on this margin. The quantity opposite the lower end of
this distance will be the cubic feet of free air per minute pass-
ing through the hose under these conditions.
The line inclined towards the right, which passes through the
intersection of lines representing hose diameter, and the hori-
zontal line representing the cubic feet of air passing through
the hose at actual density in same, shows the actual velocity
in the hose in feet per second.
For friction loss over 10 in. of mercury, use the figures
at the right hand of the lower margin, instead of those in the
right hand margin, and pass vertically to the hose diameter.
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86
VACUUM CLEANING SYSTEMS
free Air^Cu. F+. per Minute
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Friction Los6. Iru Mercury
PIG. 48. CHART FOR DETERMINING HOSE FRICTION.
Then proceed as before. As these high frictions are seldom
used in practice, this departure has been made in order to re-
duce the size of the diagram.
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HOSE 87
To illustrate how much the friction tables, based on air at
atmospheric density, vary from actual results, two tests made
by the author are given. In the first test it was desired to
pass 68 cu. ft. of free >air per minute through a %-in. diameter
orifice at the end of 100 ft. of 1-in. diameter hose. Tests on
larger hose showed that, to permit this quantity of air to pass
through the orifice, a vacuum at the orifice of 2.6 in. mercury
was necessary. The most rational table the writer could find
indicated that the friction loss in the hose should be 18 in.
mercury, and the final vacuum necessary at the hose cock would
have to be 20.6 in. mercury. On test it was found that, with
24.8 in. vacuum at the hose cock, but 50 cu. ft. of free air per
minute was passing, with a vaxjuum at the orifice of 1.6 in.
mercury, showing a friction loss of 23.2 in. mercury. With the
smiallor quantity of air passing, the same friction table indicated
a friction loss, with this quantity of air, of but 9.8 in. mercury,
or 39% of that actually observed. Checking the results of the
test with the diagram (Fig. 48) gives 50 cu. ft. of free air,
with a friction loss of 23 in. mercury.
To illustrate more clearly the effect of the increase of ve-
locity on the friction loss^ the actual vacuum in the hose has
been computed for each 10 ft. of its length and curves drawn
through these points. The results are shown in Fig. 49. The
straight line indicates the vacuum which should exist were the
velocity in the hose constant throughout its length, and the
curved line shows the vacuum in the hose when the effect of
the increasing velocity, due to the rarefaction of the air, is con-
sidered. The wide variation in the results shows clearly the
error in the former assumption of a constant velocity in the
hose throughout its length.
Another test, in which 44 cu. ft. of free air was passed
through 100 ft. of 1-in. diameter hose, is shown graphically in
Fig. 50, which discloses that the assumption of a constant velo-
city in the hose produces an error of 35% in the results, indi-
eating a loss of but 7.8 in., when the actual loss is 12 in. mercury.
Naturally, the lower the final vacuum at the hose cock, the
less will be the error due to the assumption of constant velocity
in the hose. Tests with 15^ -in. hose gave results which agree
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88
VACUUM CLEANING SYSTEMS
substantially with the result given in tables already published,
and it was this condition that led to the discovery of the error
in the assumption stated.
24
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10 20 30 40 50 60 70
Length of Hose. Fee+
80
90 100
FIG. 49. EFFECT OF INCREASE OF VELOCITY ON THE
FRICTION LOSS.
Effect of Hose Friction. — ^As any increase in the degree of
vacuum necessary to be maintained at the vacuum producer
over that maintained within the renovator requires a greater
expenditure of power, without any increase in the efficiency
or speed of cleaning, it is essential that the friction loss in the
air conduit from the renovator to the vacuum producer should
be made as small as possible. The friction loss in the hose is
the greatest loss in any part of the system, being the smallest
in diameter, and its reduction to the lowest figure possible is
of vital importance.
Take, for example, the use of a Type A renovator with a
vacuum within tiie renovator of 4)4 in. mercury and with 29
cu. ft. of air passing through same. The friction loss, with vary-
ing lengths of diflferent-sized hose, will be as follows:
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HOSE
89
TABLE 6.
Vacuum at Hose Cock with Type A Renovators and with Varying
Lengths of Different-Sized Hose.
Size of Hose.
Length, in Feet.
In. Diameter.
100
75 50
25
Vacuum at hose cock, in. hg.
1
10
6
5.0
SVi 7
5.7 5.25
4.85 4.75
5^
4.85
4.62
This indicates, first, that a much lower friction loss will
result with the use of larger hose than is the case with the
smaller size. Note, also, that the diflference in the final vacuum
at the hose cock is much more uniform when the larger-sized
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PIG. 60. ANOTHER TEST SHOWING FRICTION LOSS DUB TO
VELOCITY.
hose is used in varying lengths. Since it is desired to main-
tain a constant vacuum at the renovator at all times and it is
also desirable to be able to vary the length of hose to suit the
conditions of the work, while it is not convenient to vary the
vacuum at the hose cock, much more uniform results will be
possible when larger hose is used. If the smaller hose is used ill
varying lengths and a practically uniform vacuum is main-
tained at the hose cock, the quantity of air and the vacuum
at the renovator will vary. If 1-in. hose is used and the vacuum
at the hose cock be maintained at 10 in. mercury, the air quan-
tities and vacuum at the renovator will be approximately :
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VACUUM CLEANING SYSTEMS
TABLE 7.
Am Quantities and Vacuum at Renovator with 1-in. Hose and 10-in.
Vacuum at Hose Cock.
Length of Hose,
feet.
ioo
75
SO
25
Vacuum at Renovator,
in. hg.
5
6y2
W2
Air, cu. ft.
29
32
34
H. P. at Hose Cock.
0.80
0.885
0.94
1.02
From this it is evident that the vacuum within the renovator
will be increased above that necessary for economical cleaning.
It will require somewhat more effort to push the cleaner over
the carpet and also a slightly greater expenditure of power at
the hose cock to operate the cleaner with a short than with a
long hose. However, the author does not consider that either
the increase of effort to push the renovator or the increase of
power will be sufficient to prohibit the use of 1-in. hose with
the Type A renovator.
If we use \y^A\i, hose with Type A renovator and maintain
a vacuum of 6 in. of mercury at the hose cock, the resulting
vacuum and air displacement at the renovator will be:
TABLE 8.
Ant Quantities and Vacuum at Renovator with 1^-in. Hose and 6-in.
Vacuum at Hose Cock.
Length of Hose,
feet.
ioo
75
50
25
Vacuum at Renovator,
in. hg.
4^2
4.7
5.0
5.4
Air, cu. ft.
29
30
ZZ
35
H. P. at Hose Cock.
0.43
0.445
0.448
0.518
This table shows a more uniform degree of vacuum at the
renovator with the varying length of hose, but the greatest
difference is in the horse power required at the hose cock to
accomplish the same results at the renovator.
If we use 13/2 -in. hose with Type A renovator, the vacuum
at the hose cock can be reduced to 5 in. mercury and a prac-
tically constant vacuum will be obtained at the renovator, with
an expenditure of 0.36 H. P. at the hose cock.
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HOSE 91
With the Type C renovator where the vacuum within the
renovator is maintained at 4 in. mercury, with 44 cu. ft. of free
air per minute passing through the renovator, the resulting
vacuum at the hose cock, with various lengths of the three sizes
of hose, will be as follows:
TABLE 9.
Vacuum at Hose Cock, with Type C Renovators and Various Lengths
OF Three Sizes of Hose.
Size of Hose,
IiL Diameter.
Length, in Feet.
100
75 50
25
Vacuum at hose cock, in. hg.
1
1^
19
7.5
5.1
14 10
6.25 5.5
4.80 4.50
6.7
4.7
4.25
Referring to Fig. 17, Chapter III, it will be noted that Type
C renovator will not accomplish much in the way of cleaning
with a vacuum in the renovator lower than 4 in. mercury. There-
fore, if we use this type of renovator, with 1-in. diameter
hose, its length should be limited to 50 ft, for if we use a
vacuum higher than 10 in. at the hose cock, there will be too
much increase in the vacuum at the renovator when short hose
is used to allow easy operation, and if we use longer hose with
10-in. vacuum at the hose cock, there will be a reduction in the
vacuum at the renovator and effective cleaning cannot be ac-
complished. Also, the power required at the hose cock to pass
44 cu. ft. of air, with a vacuum of 19 in. mercury, required to
produce a vacuiun of 4 in. at the renovator with 100 ft. of 1-in.
hose, will be 3.3 H. P., which is prohibitive when compared with
that required with the use of larger hose, i. e., 0.825 H. P.
with lj4-in. hose and 0.59 H. P. with 1^4 -in. hose.
The Type F renovators tested by the author will show even
wider variations in the vacuum required at the hose cock with
the various lengths and diameters of hose than is given for
Type C renovator. However, the type F renovator, which is
now used by the Spencer Turbine Cleaner Company, having a
cleaning slot 15 in. long and Yz in. wide throughout its length.
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92 VACUUM CLEANING SYSTEMS
paisses 44 cu. ft. of free air per minute, with a vacuum under
the renovator of 4 in. mercury and the resulting vacuum at the
hose cock will be the same as that given in the case of the Type
C renovator.
When a bare floor renovator of the bristle-brush type is at-
tached to the hose, the effect is practically the same as when
the end of the hose is left wide open, as the open character of
the brush prevents the formation of any vacuum in the reno-
vator. Therefore, suflScient air must pass through the reno-
vator to create a friction loss in the hose equal to the vacuum
at the hose cock.
As practically all systems are arranged to maintain a con-
stant vacuum at the vacuum producer and as the pipe friction
is generally less than the hose friction, the vacuum at the hose
cock will be practically the same when operating a floor brush
as with a carpet renovator.
Assuming that 10 in. mercury is maintained at the hose cock
with 1-in hose, 6 in. with lj4-iJi- hose, and 5 in. with IJ^-in.
hose, the quantity of air which will pass through a floor brush
with various sizes and lengths of hose will be:
TABLE 10.
Air Quantities Through Floor "Brush Operated in Conjunction with
Type A Renovators.
Size of Hose.
Hose Length, in Feet.
Tn Diameter
100
75 50 25
Cubic feet of free air per minute.
1
42
62
95
48 60 86
72 86 125
110 135 190
The quantities given for the shorter hose lengths are higher
than will be observed in actual practice, due to the increase in
the pipe friction, which will depend on the length of the pipe
lines. However, the results will illustrate the great increase
in the quantity of air which will pass these bare floor brushes
when operated on the same system with carpet renovators. If
the same number of bare floor renovators are to be used at
one time as there will be carpet renovators at some other time,
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HOSE 93
that is, if the sweeper capacity must be maintained when using
bare floor brashes as when using carpet renovators, a much
larger air exhausting plant must be installed than would be
necessary to operate that number of carpet renovators.
If it were possible to so arrange the schedule of cleaning
operations that bare floor brushes were never used at the same
time as carpet renovators, the vacuum at the machine might be
reduced when operating the floor brushes to a point that would
reduce the quantity of air passing to within the capacity of a
machine designed to operate the same number of carpet reno-
vators. Unfortunately, this condition rarely exists and, there-
fore, the vacuum must be maintained at the degree necessary
to operate the carpet renovators that may be in use at the
same time with the floor brushes.
It is also evident that if the length of hose used with bare
floor brushes could be limited to the maximum ever used with
the carpet renovators, a reduction in the capacity of the ex-
hauster necessary could be made. This is another condition
which the designer of the system cannot control.
Most Economical Hose Size for Carpet and Floor Reno-
vators. — The horse power required at the hose cock to operate
the bare floor brushes with each of the different sizes and
lengths of hose is:
TABLE 11.
H(«SE Power Required at Hose Cock to Operate Bare Floor Brushes
IN Conjunction with Type A Renovators.
^170 of Hn^ft
Length, in Feet
In Diameter
100
75 50
25
Horse power at hose cock.
1
1.16
0.92
1.15
1.32 1.65
1.06 1.27
1.32 1.62
2.38
1.38
228
This shows that where bare floor or wall brushes of the bristle
type are used in conjunction with carpet renovators on any
system and with Type A carpet renovator, lj4-in. diameter
hose will give the lowest power consumption.
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94
VACUUM CLEANING SYSTEMS
When either Type C or F renovator is used in combination
with bristle-type brushes, the use of 1-in. diameter hose must
be abandoned in lengths over 50 ft. and the vacuum at the hose
cock must be maintained at 10 in. mercury. With lj4-iii« hose,
it will be necessary to maintain a vacuum at the hose cock of
7 in. mercury, and, with IJ^-in, hose, 5 in. will be sufl&cient, pro-
vided we continue to use 100 ft. of hose in the case of the larger
sizes. The free air passing a brush type of bare floor reno-
vator under these conditions will be:
TABLE 12.
Free Am Passing Brush Type of Bare Floor Renovator Operated in
Conjunction with Type C Renovators.
Size of Hose,
Tn T^iameter
Length, in Feet.
100
75 50 25
Cubic feet of free air per minute.
k
42
68
95
48 60 86
76 92 130
110 135 190
This shows an increase in the volume of air passing the floor
brush with lj4-iii- hose, while a higher vacuum is now carried
at the hose cock than was necessary when Type A renovator
was used in conjunction with the bristle-type of floor renovator.
The horse power at the hose cock will now be :
TABLE 13.
Horse Power at Hose Cock with Brush Type of Bare Floor Renovator
Operated in Conjunction with Type C Renovators.
Sizp of Hose
Length, in Feet.
In Diameter.
100
75 50
25
Horse power at hose cock.
1
1.16
1.19
1.15
1.32 1.65
1.36 1.60
1.32 1.62
2.38
2.26
2.28
With this combination of floor and carpet renovators, there
is no difference in the power consumption when any one of the
three sizes of hose is used. However, there is a considerable
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HOSE 95
increase in the quantity of air passing the larger hose. This
leads to the statement made by some manufacturers that this
increase in air volume results in more efficient cleaning.
Tests given in Chapter III indicate that increase in air vol-
ume does not result in any more rapid or efficient cleaning of
carpets. The results of actual use of the bare floor brush of
the bristle type show no gain when cleaning bare floors. As
stated in Chapter IV, the felt-faced renovator, being more
eflPective while it requires less air. In other words, it is the
degree of vacuum within the cleaner and not the quantity of
air which produces the cleaning in all cases where any degree
of vacuum is possible. When intimate contact between the
cleaner and the surface cleaned cannot be had, the volume of air
determines the efficiency of cleaning. However, the author
does not consider that an exhaustion of more than 60 to 70
cu. ft. of free air through cleaners of this type will increase
the efficiency to such an extent as to justify the increase of
power necessary to adapt a system to larger volumes.
The author considers that with a system in which brushes
of the bristle type are to be used, the exhauster should have
a capacity of 70 cu. ft. of free air per minute. Such a system
is termed by the author a *^ large volume system,'' as already
mentioned in Chapter IV.
When the felt-covered floor renovator is used instead of the
brush, the vacuum within this renovator must not be permitted
to rise above 2 in. or the operation of the renovator on the
floor will be difficult. To ax^complish this, it is necessary to
provide openings in the ends of the cleaning slot, ss has been
explained in Chapter IV. If the vacuum at the hose cock be
assumed as 10 in. with 1-in hose, 6 in. with Ij^-ij^- hose, and
5 in. with lyi-m, hose, and the vacuum within the felt-covered
floor renovator be maintained at 2 in. mercury the cubic feet of
free air passing the renovator with the various sizes and lengths
of hose will be:
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VACUUM CLEANING SYSTEMS
TABLE 14.
Cubic Feet of Free Ant Passing the Felt-Covered Floor Renovators
Operated in Conjunction with Type A Renovators.
Size of Hose,
InL Diameter
Length, in Feet
100
75 SO
25
Free air, cubic feet per minute.
1
36
49
68
43 54
56 68
78 94
74
94
130
These figures show a considerable reduction from those ob-
tained with the brush type of floor renovator, particularly when
the larger sizes of hose are used, and considerable reduction
can be made in the capacity of the exhauster and still obtain
the best results when using carpet renovator and bare floor
renovator simultaneously.
The horse power at the hose cock required to operate these
felt-faced floor renovators with different sizes and lengths of
hose are:
TABLE 15.
Horse Power Required at Hose Cock to Operate Felt-Covered Floor
Renovators in Conjunction with Type A Renovators.
Size ni Ho^e
Length, in Feet
In. Diameter
100
75 50
25
Horse power at hose cock.
k
1.0
0.72
0.79
1.19 1.49
0.83 1.0
0.93 1.13
^05
1.39
1.56
In this case, the 1^4 -in. hose is the most economical size to
use, as was the case with the brush renovators. However, the
advantage over the lj4-in. hose is not as great as with the brush
renovator.
With this type of renovator, the manufacturer has some
control over the length of hose which the operator will use in
connection with the bare floor renovator, as he may open the
ends of the renovator just suflSciently to produce 2 in. of
vacuum under same with, say, 50 ft. of hose. Then, if the
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HOSE 97
operator should attempt to use the renovator with 25 ft. of hose,
it will stick and push hard and he will soon learn that a longer
hose is necessary.
Conditions for Plant of Small Power. — For locations where
it is desirable to sacrifice efficiency somewhat to reduction in
the amount of power required, as in residences, the Type A
carpet renovator may be used and the vacuum under the same
reduced to 2 in. mercury, which will still do effective cleaning,
but at a slower rate, as was shown by tests in Chapter III.
This requires not exceeding 20 cu. ft. of free air per minute.
With this quantity of air the velocity in the hose must be
considered as, in order ta have a clean hose at all times, it is
necessary to maintain a velocity in the hose of not less than
40 ft. per second. Referring to the diagram, Fig. 48, it will
be seen that this velocity will not be obtained in any hose
larger than 1J4 in. and this is, therefore, the largest size which
can be used. In all the former cases the velocity was so much
in excess of this minimum that its consideration was not nec-
essary.
With a vacuum of 2 in. of mercury in the renovator and
20 cu. ft. of air passing, the vacuum at the hose cock will be :
TABLE 16.
Vacuum at Hose Cock, with 2-in. Vacuum at Type A Renovator.
55ize of Hose
Length, in Feet.
Tn Diameter
100
75 50
25
Vacuum at hose cock, in. hg.
1
4
2.6
3.5 3
2.45 2.3
2.5
2.15
In this case the increase in vacuum at the renovator would
not be objectionable as, with 4 in. vacuum at the hose cock, the
vacuum at the renovator would never reach the standard used
with the former deductions and the volume of air passing could,
therefore, never reach 29 cu. ft. Any increase, due to the use
of shorter hose, would, therefore, be an advantage in its ap-
proach toward the standard set for the larger plants. There-
fore, we will assume that a vacuum of 4 in. mercury will be
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98 VACUUM CLEANING SYSTEMS
nmintained at the hose ooek with 1-in. hose and a vacuum of
2y2 in. at the hose cock with lj4-in. hose.
The renovators for bare floor work will be the felt-covered
type and will be op^ened at the ends just sufl&ciently to limit the
vacuum within the same to 2 in. mercury when operating with
25 ft. of hose. This will require the passage of 40 cu. ft. of free
air per minute when 1-in. hose is used and 35 cu. ft. when
lj4-in. hose is used. The horse power at the hose cock will be
0.39 H. P. with the 1-in. diameter hose and 0.17 H. P. with the
lj4-in. hose. Here again we see that the ly^-m, hose is the
more economical to use.
If bristle brushes are used with this system at the same time
that carpet renovators are in use, the. quantity of air which
will have to pass them, in order to maintain the vacuum on the
system at the proper point to do effective cleaning with the
carpet renovators, will be :
TABLE 17.
Air Quantities When Bristle Bare Floor Renovators Are Used in
Conjunction with Type A Carpet Renovators at 2 in. Hg.
Size of Hose
Length of Hose, in Feet.
In. Diameter.
100
75 50
25
Free air, cu. ft. per minute.
1
30
41
36 42
48 60
60
80
The use of these brushes in plants of more than one-sweeper
capacity would require the use of an exhauster of greater
capacity than is required for either the carpet or the bare
floor renovator. Where the plant is of but one-sweeper capacity,
the quantity of air that would pass these brushes, were the
plant of proper capacity to serve the carpet and floor reno-
vators, would not be sufl&cient to do effective work, as was ex-
plained in Chapter IV. In such cases, this arrangement should
be prohibited.
A system of the type just described is what has been termed
by the author as a ** small volume" plant in Chapter IV.
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HOSE 99
Limit of Length for Hose. — The author has made the de-
ductions in this chapter, using 100 ft. of hose as the maximum
length. This is considered to be the greatest length that should
be used. The adoption of a shorter length is recommended by
many manufacturers, but the author does not consider that the
advantage to be obtained by the adoption of a shorter length
justifies the additional expense of piping which will result in
many^ cases. This will be governed by the character of the
building and, in many cases, it will be possible to use 50 ft. as
a mstximum. It has been the practice of the author to lay out
his installations so that any point on the floor of any room may
be reached in the most direct line with 75 ft. of hose. "When
this is done 100 ft. of hose will easily clean any part of the
walls or ceilings and give an ample allowance for running
around furniture or other obstructions.
The figures in this chapter will demonstrate to the reader the
part that the cleaning hose plays as a limiting factor in the
operation of a vacuum cleaning system and shows the care
that must be exercised in the selection of the proper hose for
each condition.
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CHAPTER VII.
Pipe and Fittinqs.
As we continue to follow the dust-laden air in its passage
toward the vacuum producer we next encounter that portion of
the conduit which is permanently and rigidly fixed in place
in the building; namely, the pipe line, its fittings and other
appliances.
Hose Inlets. — The first portion of this conduit which we
must consider is the point where the hose is attached to the
pipe line ; that is, the inlet, or, as it is often improperly termed,
the ** outlet'' valves.
As it is necessary to close the inlets air tight when they are
not in actual use, in order to prevent the entrance of air except
through the hose lines in use, some kind of a cut-oflf valve must
be provided, as well as a receptacle into which the end of the
hose may be connected when desired.
With the earlier systems a high degree of vacuum was carried
in the pipe lines and the vacuum producers were of small dis-
placement. Slight leakage would greatly reduce the capacity
of the system and the best form of valve was necessary. The
valve adopted was the ordinary ground-seat plug cock, on ac-
count of its unobstructed air passage and air-tight closing. The
hose was connected to tiiese cocks either by a ground-joint,
screwed coupling or by a slip coupling similar to those used to
unite the sections of the cleaning hose. An inlet cock of this
type is illustrated in Fig. 51.
These cocks projected about 4>^ in. beyond the face of the
finished wall and formed a considerable obstruction, especially
when located in halls or corridors. In order to reduce the pro-
jection into the apartment the manufacturers of the systems
using screwed-hose couplings and substituted a projecting
nipple closed by a cap screwed in place. The whole projected
only ^ in. beyond the finished wall line.
100
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PIPE AND FITTINGS
101
These outlets were suitable for use only with hose having
screwed connections. When an attempt is made to remove
the cap with the vacuum producer in operation, there is a ten-
dency for the vacuum to cause the cap to hug the last thread
and render its removal difficult. Also, when the suction is
finally broken it is accomplished with considerable hissing
noise.
In order to permit the use of the slip type of hose coupling,
a* hinged flap valve was substituted for the screwed cap, a rub-
ber gasket being placed under the cap. This was held firmly
in place by the vacuum in the pipe line. The interior of the
casting inside of the flap was turned to a slip fit for the end
of the hose coupling. With this type of valve and the slip hose
coupling, described in Chapter VI, it is possible to reverse the
hose to equalize wear and remove obstructions.
These inlets have been made with valves that are closed
only by gravity when there is no vacuum on the system and
many are so constructed that when opened wide they will re-
main open with the vacuum on the piping. This type of valve
PIG. 51.
INLET COCK TO PREVENT AIR LEAKAGE WHEN NOT
IN USE.
will often be opened by the inquisitive person when no vacuum
exists in the system and as there are no immediate results,
they may be left open with the result that there will be a very
large leakage of air on starting the vacuum producer. This
makes it necessary for some one to make a tour of the building
in order to close the valve which is open before the system can
be efficiently operated. If the vacuum producer is designed
to operate several renovators simultaneously, it may not be
discovered that there are any valves open and a considerable
amount of power will be wasted.
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102
VACUUM CLEANING SYSTEMS
In order to overcome this difl&culty it is necessary to provide
a spring on the hinge of the flap valve that will automatically
close the valve whenever the hose is withdrawn. When the
inlets are located in public places they should be fitted with a
lock attachment to prevent them from being opened by unau-
thorized persons.
A valve of this type is illustrated in Fig. 52. This valve
has a projection on its inner face which engages with a ridge
on the hose couplings, preventing the removal of the hose with-
out slightly raising the cap and making it impossible to acci-
dently pull the hose out of the inlet.
PIG. 52. TYPE OP AUTOMATIC SBLP-CLOSINO INLET COCK.
The particular valve here shown is suitable for use only with
the all-rubber hose connection described in Chapter VI.
We must next consider the material of which the conduit
itself is to be made. The commercial wrought-iron or mild
steel, screw-jointed pipe, such as is used for water and steam
lines, is probably the best suited for this purpose and was the
first materiial used. In earlier installations the pipe was gal-
vanized, but, owing to the tendency for the zinc coating to
form irregularities within the pipe, its use has been aban-
doned in favor of the commercial black iron pipe.
Seamless drawn tubing would undoubtedly make the ideal
material for this purpose. However, the ordinary butt or lap-
welded pipe is satisfactory and is now generally used.
Sheet metal pipe was introduced by one manufacturer but
its use was shortly abandoned in favor of the commercial pipe.
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PIPE AND FITTINGS 103
As joints and changes in direction are necessary in the pipe
lines, some sort of fittings must be used. The ideal conduit for
passage of dust-laden air should be of uniform bore and as
smooth on the inside as a gun barrel. Various attempts have
been made to accomplish this result in commercial installations,
one of which is illustrated in Fig. 53. These fittings are made
up of three parts for a coupling and four for a branch or
change in direction. One of these is screwed on to the end of
each piece of pipe, the pipe butting against a shoulder and the
end of the pipe made to register with the bore of the fitting by
reaming. This piece is faced true and fitted against the face
of the casting, forming the bend or branch, or fitted against
the i^iece on the end of the other length of pipe. A thin gasket
is placed between them, a projecting ring on one piece fitting
FIG. 53. "SMOOTH BORE" PIPE COUPLING.
into a groove on the other, causing the bore of the two halves
to register. The two halves are joined together by the
V-grooved clamp, held in place by a small bolt. This is theo-
retically an ideal joint, but the clamp is not of sufficient
strength to withstand the strain of settlement of the building
and breakages are frequent. Several instances of this character,
particularly on steamers, have come to the observation of the
author, and there are several buLLdings which have been roughed
in with this type of fitting, used on concealed piping, which were
found to be useless on the completion of the building, due to
breaking of the joints in inaccessible places.
A modification of this joint which will have ample strength
can be made by using standard pipe flanges, screwing the pipe
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104
VACUUM CLEANING SYSTEMS
through the flange and facing the end off in a lathe. Fittings
could be made with a bore equal to that of the pipe and proper
alignment secured by the use of dowel pins, as illustrated in
Fig. 54. The cost of making this joint would be high and they
would occupy too much space to be easily concealed in par-
titions, furring or other channels usually provided for the
reception of such piping.
The standard Durham recessed drainage fitting, having the
inside cored to the bore of the pipe and recesses provided for
the threads as used in connection with the modem plumbing
system, if left ungalvanized and having the inside well sand-
blasted to remove all rough places, makes a serviceable fitting.
Care should be exercised to cut the threads on the piping of
PIG. 54. JOINT MADE OF STANDARD PIPE FLANGES.
proper depth to allow the end of the pipe to come as close to
the shoulder of the recess as practicable and to obtain a tight
joint. The end of the pipe should be carefully reamed before
assembling.
These fittings have become standard with nearly all manu-
facturers and are illustrated in Fig. 55, which shows the right
and wrong way to install same.
Trouble was experienced on some of the earlier systems using
high vacuum with the fittings cutting out on the side sub-
jected to the impact of the dust-laden air. To overcome this
trouble one manufacturer re-inforced the fittings by increasing
the thickness of metal at the point affected. The trouble was
undoubtedly caused by too high a velocity in the pipe line, as
in the case of the small brass stems, explained in Chapter V.
With the introduction of vacuum control and larger pipes.
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PIPE AND FITTINGS
10e5
this trouble disappeared and the special fittings never came
into general use.
While the utmost care should be taken to prevent stoppage
of the pipe lines these stoppages are likely to occur in the best-
RIGHT WAT. WRONG WAT.
To Cleaner
To Cleaner
Use fwo Y- branches insfeaof cf sfraiofhf or cleanouf fees. In case the laihrang used
the dirt will siioof by inio the of her branch.
Tb Cleaner _ j j '^_
■?
:2
Id Cleaner
-&
i
j4lvyays place Y- branches so f hey will turn in the ctirection of the flov^.
To
ffi
Cleaner 77 -7
To Cleaner
Place fhe clean -out atricfht angles to the direction of flov/ entering the
fittincf. Otherwise it series as a pocket to catch passincf dirt
C^Riser
To Cleaner P-?
Drop
To Cleaner
To Cleaner
Special care must be exercised I0 see that there is no opportunrty -for dirt to coilecf in ihe
basement drops, Aboye is shomt a common wroncf way and tm? possibie right ways,
FIG. 55. STANDARD DURHAM RECESSED DRAINAGE FITTINGS
GENERALLY USED IN VACUUM CLEANING INSTALLATIONS
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106 VACUUM CLEANING SYSTEMS
constructed lines and ample clean-out plugs should be provided
for the removal of such stoppage. Brass plugs are the most
serviceable for this purpose, as they are easily removed when
necessary and can usually be replaced air tight.
The brass clean-outs, while most satisfactory, are costly when
installed in large sizes. Equally satisfactory results can be ob-
tained at a lower cost by using 2-in diameter plugs on all lines
2 in. and over in diameter.
Veloci+y in Pipe, Ph per Sec LenorHi of Pipe, Feef
I I
.fc E
< I
% t
Average VocuuKn in Pipe, In. Mercury
PIG. 56. FRICTION LOSS IN PIPE LINES.
Matches are perhaps the most frequent cause of stoppage in
pipe lines. Stoppage from this cause can be largely avoided
by the use of pipe of sufficient size to permit the match to turn
a complete somersault within the pipe whenever it catches
against a slisrht obstruction or rough place in the pipe or
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PIPE AND FITTINGS , 107
fittings. A 2-in. diameter pipe is just large enough to permit
this and smaller sizes of pipe iShould be avoided whenever
possible,
Pipe Friction. — The friction loss in piping follows the same
law as that in hose lines and is easily computed by use of the
chart (Fig. 56), which is constructed on the same general
principle as the chart of hose friction (Fig. 48). The directions
for use of the hose chart apply to the pipe tfhart. In computing
this chart the actual inside diameter of the commercial wrought-
iron pipes have been used instead of the nominal diameters,
resulting in an increased capacity for all sizes except 2>^-in.
which is less than the nominal diameter.
Determination of Proper Size Pipe.— Friction in the pipe
lines tends to increase the vacuum to be maintained and there-
fore the power to be expended at the vacuum producer and
should be kept as low as possible. The pipe sizes should be
made as large as conditions will permit. The limit of size is
fixed by the velocity in the pipe. When it is necessary to lift
the dirt to any extent, the velocity should not be allowed to
fall below 40 ft. per second at any time. When the pipe is a
vertical drop, the velocity does not matter as gravitation will
assist the air current in removing the dirt. When the line is
horizontal a lower velocity than 40 ft. per second is permissible
at times, provided that this minimum velocity is exceeded at
frequent intervals to flu^ out any dirt that has lodged in the
pipe during periods . of low velocity.
If a Type A renovator is used with 1-in. hose and a vacuum
of 10 in. of mercury maintained at the hose cock, the minimum
air passing, with 100 ft. of hose in use, will be 29 cu. ft. of free
air per minute, which is equivalent to 44 cu. ft. at 10 in. of
vacuum. The entering velocity in the pipe should be calculated
with air at this density. This will give a velocity of 50 ft.
per second in a l>^-in. pipe, but only 30 ft. per second in a 2-in.
pipe. Therefore, the IJ^-in. pipe is the largest. that should be
used where lifts occur on a line serving but one Type A reno-
vator with 1-in hose. When the renovator is tilted at a con-
siderable angle or lifted from the carpet, as will frequently
occur in cleaning operations, the quantity of air passing the
renovator will be upwards of 42 cu. ft. of free air, equivalent
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108 VACUUM CLEANING SYSTEMS
to 62 cu. ft. at 10-in. vacuum. 'When this occurs the velocity
in a 2-in. pipe will be 44 ft. per second, which will be ample to
flush a horizontal line of piping.
If lj4-in hose is used with a Type A renovator, the minimum
quantity of air will be 29 cu. ft. and the vacuum entering the
pipe will be 6 in. mercury, giving an equivalent volume *of 37
cu. ft. This will produce a velocity of 42 ft. per second in a
IJ^-in. pipe, which is the largest that can.be used where a lift
occurs. However, when the renovator is lifted free of the
carpet, the air quantity will be 62 cu. ft. of free air, equivalent
to 80 cu. ft. at 6 in. of vacuum, and will produce a velocity
of 39 ft. per second in a 2>^-in, pipe. This would be just about
sufficient to flush a horizontal line.
If Ij^-in. hose were used the air quantity will be 29 cu. ft.
and the vacuum entering the pipe 5 in. mercury, equiva-
lent to 35 cu. ft. This will give a velocity in a IJ^-in. pipe of
40 ft. per second. When the renovator is raised from the car-
pet, the air quantity will be upwards of 90 cu. ft. of free air,
equivalent to 110 cu. ft. at the density of that entering the pipe,
and will produce a velocity of 33 ft. per second in a 3-in. pipe.
This is too low to thoroughly flush a horizontal pipe.
The figures given above are repeated from Chapter VI and
show that the use of lj4-iii- instead of 1-in. hose, permits the
use of a larger-sized horizontal pipe line for serving one reno-
vator, but that the use of lj4-in. hose, instead of lj4-iii-> will
not permit of any enlargement in the pipe size. Since we have
seen in Chapter VI that a lj4-i^i- lw)se gives the least expen-
diture of power when used with a Type A renovator, there
will be no gain from a reduction in the pipe friction due to
the adoption of this hose.
The dependence on the raising of the renovator from the floor
to flush out a larger pipe line should not be carried beyond that
to be obtained from a single renovator. That is, when the pipe
must serve more than one renovator at the same time, the quan-
tity of air that two or more renovators will pass, if they were
raised from the floor at the same time, should not be used in
determining the limiting velocity in the pipe, as such an occur-
rence is not likely to be obtained often enough to thoroughly
flush the pipe. Furthermore, there will be times when this pipe
will have to serve only one renovator and the pipe will not be
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PIPE AND FITTINGS
109
adequately flushed. When the pipe is serving more than one
renovator, the actual air passing the renovators should be used
in determining 4;he maximum size of pipe and it is advisable to
use this maximum size in nearly all cases where the structural
conditions will permit.
These sizes will then be:
TABLE 18.
Pipe Sizes Requibed, as Determined by Air Passing Renovators.
Number of Renovators in Use.
Cu. Ft.
per min.
Pipe Sizes
With 1-in.
Hose.
In. Diam.
With IK-in.
Hose.
1
2
3
4
5
6
29
58
87
116
145
174
2
254
3
3H
sy2
4
2H
2K2
3
3^
3/2
4
Using these maximum sizes, the friction loss in a pipe line,
with carpet renovators in use exclusively, will be:
TABLE 19.
Friction Loss in Pipe Lines, with Carpet Renovators in Use
Exclusively.
Number of Sweepers.
Friction Loss
per
100 Feet,
Inches.
With 1-in. hose.
With IK-in. hose.
1
2
3
4
5
6
0.20
0.30
0.24
0.19
0.30
0.24
0.06
0.20
0.17
0.13
0.22
0.17
These friction losses are figured with a density of air in the
pipe equal to 6-in. vacuum in ease of the V/i-in. hose and 10-in.
vacuum in case of the 1-in. hose, which will be the density of
the air entering the pipe, while the average density should be
used in order to give correct results. If the pipe line is not
over 400 ft. equivalent length the results will be approximately
correct.
These results show, first, that the friction loss in pipe lines
is much lower than that in the hose lines used with the same
system; second, that the higher vacuum in the pipe causes
greater loss, an argument in favor of the use of larger hose.
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110 VACUUM CLEANING SYSTEMS
These friction losses are obtained only when carpet reno-
vators are used exclusively and all the renovators are held in
the proper position to perform the most economical cleaning.
In actual practice this condition will not exist except when one
renovator is used. Where more than one renovator is in use
simultaneously, some of the renovators will be raised from the
floors at the time others are in position to do effective cleaning
Irvac
Rruih b
40Cu.Ft
^ ZOO'Z'Pipt P 2O0''IVpid9 ^
75 Cu. Ft Carpet Ftnovafor -a'
il'Yac ZSCaFf
A Z00''2'Pip€ B Z0O'-li'pip€ C
^ 6rusf?
Car/oef/^errovafor SSCaFf
S'YacZSCuFt:
.. A 200'-li'PiPt B ZOO'-ZfPiDe C
Carpet Renovator ^f-^^ IZOCu.Ft
27" Vac 24. Cu. Ft.
FIGS. 57-60. DIAGRAMS SHOWING OPERATION OP BRUSH AND
CARPET RENOVATORS UNDER DIFFERENT CONDITIONS.
and will admit a greater quantity of air, increasing the friction.
This is not a serious condition as the time that the renovators
will be raised is only a small part of the total time spent in
cleaning and will merely reduce the efficiency of the other
renovators temporarily. However, when brushes or floor reno-
vators are used at the same time as the carpet renovators, there
will be a continuous flow of air in greater quantities through
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PIPE AND FITTINGS 111
these brushes, which will permanently increajse the friction loss.
The use of a single brush or floor renovator with the same sized
pipe as is necessary to operate the carpet renovator will not
reduce the efficiency of the brush, as a high degree of vacuum
3,t the brush or floor renovator is not necessary or even per-
. missible and a further slight reduction will not aflfect the oper-
ation of these renovators.
When a brush or floor renovator is used on the furthest out-
let from the vacuum producer at the same time that carpet
renovators are being used on outlets nearer the vacuum pro-
ducer, the larger quantity of air passing the brush will tend to
reduce the vacuum at the hose cock to which the carpet reno-
vator is attached and thereby impair its efficiency. For ex-
ample, if we have a brush renovator connected through 100 ft.
of 1-in. hose to an outlet at the end of a pipe line 400 ft. long,
properly designed to serve two carpet renovators, the vacuum
at the separators should be maintained at 10-in., plus 2X0«20
plus 2X0.30, or 11 in. of mercury. Suppose that this vacuum
is automatically maintained at this point and a carpet reno-
vator be attached 200 ft. from end of pipe (Fig. 57). The
quantity of air passing through the 2^ -in. pipe B-C will be
approximately 29 plus 40 or 69 cu. ft., and the friction loss in
this pipe will be 1.1 in. The vacuum maintained at the outlet
B (Fig. 57) will be 9.9 in. or approximately the correct vacuum
to maintain 4j/$-in. vacuum at the renovator **a." The friction
loss in the pipe line from B to A will be 0.7 in. and the re-
sulting vacuum at the hose cock A will be 9.2 in. The quantity
of air passing the brush will be 40 cu. ft. Under these con-
ditions there will be no loss in efficiency of cleaning due to the
brush renovator being used on the end of the line. If the
operator using the brush at the outlet A should use only 25
ft. of hose instead of 100 ft. (Fig. 58) the air passing this
brush will be 75 cu. ft. and the vacuum at the hose cock A
will be 6.8 in. The vacuum at the hose cock B will be 8.8 in.
and the vacuum at the carpet renovator **a" will be reduced
to 3^4 in. with 25 cu. ft. of air passing, which will reduce
the efficiency of the carpet renovator *'a.''
If the brush renovator be attached to the hose cock B (Fig.
59), using 25 ft. of hose, the vacuum at hose cock B will be
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112 VACUUM CLEANING SYSTEMS
9 in. and the brush renovator will pass 85 cu. ft. of air, while
the vacuum at hose cock A will now be reduced to 8.6 in. and
the vacuum at tfoe renovator will be reduced to 3 in. mercury
and the air passing to 23 cu. ft.
If a brush tyi>e of renovator be used at each outlet, with 25
ft. of hose in each case and the vacuum at the separator be
maintained at 11 in. mercury the vacuum at hose cock B will
be 7 in. and brush **a" will pass 76 cu. ft. of air while the
vacuum at hose cock **a" will be 5 in. and brush **b" will
pass 63 cu. ft. of air or a total of 144 cu. ft., which will be
in excess of the 70 cu. ft. per renovator, recommended as the
capacity of the plant in Chapter VI. This will not result in
any loss of eflRciency if the vacuum producer be designed to
handle but 140 cu. ft. as a maximum, for the vacuum at the
separator will then fall to a point where but 140 cu. ft. passes,
resulting in a decrease in the vacuum throughout the system.
But as only brushes are now in use there will be no loss in
efiiciency, owing to the reduction in the vacuum at the brushes.
When lj4-in. hose is used with a carpet renovator at the end
of the pipe line connected through 100 ft. of hose and a brush
at the hose cock B connected through 25 ft. of hose (Fig. 60),
the worst case of the three already cited, the vacuum at the
separator being maintained at that necessary to carry 4j^ in.
when two carpet renovators are in use, the vacuum at the hose
cock B will be 4.5 in. and brush '*a" will pass 116 cu. ft. of
air while the vacuum at hose cock A will be 4.4 in. and the
vacuum in renovator **b" will be 3.7 in and will pass 24
cu. ft. of air.
These are better cleaning conditions than were obtained when
1-in hose was used. It. will be noted that the total air passing
the exhauster is now 140 cu. ft. and this must not be reduced
or there will be a falling oflf in the vacuum at the carpet reno-
vator **b." It is, therefore, necessary for the exhauster to be
capable of handling 140 cu. ft. of air or 70 cu. ft. of air per
renovator in order to do effective carpet cleaning when carpet
renovators and brushes are used in conjunction.
When two floor brushes are used with the above arrange-
ment of pipe and hose, the vacuum must fall considerably or
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PIPE AND FITTINGS 113
the air quantity be greatly increased. However, the reduction
in vacuum will not result in serious loss in efficiency when only
brushes are in use.
When a larger number of sweepers are used with a system
of piping, it is necessary to allow 70 cu. ft. of free air per
sweeper in figuring the sizes of pipe to be used, and the total
loss of pressure in the piping between the outlet farthest from
the vacuum producer and that nearest to same must be limited
in order to prevent too wide a diflference in the vacuum at the
hose cock when all the sweepers for which the plant is designed
are in use. The author considers that this loss in pressure
should not be greater than 2 in. mercury in order to give satis-
factory results.
Before the piping system can be laid out and the sizes of
piping determined it is necessary to ascertain, first, the num-
ber of sweepers to be operated simultaneously and the number
of risers necessary to properly serve these sweepers.
Number of Sweepers to be Operated. — This is determined
by the character of the surfaces to be cleaned, the amount of
such surface, and the time allowed for cleaning.
It has been demonstrated in actual practice that one operator
can clean as hig'h as 2,500 sq. ft. of carpet when same is on
floors of comparatively large areas, and not over 1,500 sq. ft.
when the carpets are on small rooms ; 2,000 sq. ft. is considered
to be a fair average.
Bare floors are cleaned more rapidly. In school house work
an ordinary class room has been cleaned in 10 minutes, or at
the rate of 7,200 sq. ft. per hour, but time is occupied in moving
from one room to another and the writer considers 5,000 sq. ft.
per hour as rapid cleaning and 3,500 sq. ft. as a fair average.
The time of cleaning will vary in buildings of different char-
acter and used for different purposes. In office buildings the
cleaning force work throughout the night or about 10 hours,
w*hile in school houses the cleaning is done by the janitor force
which has been on duty throughout the school period and the
time is necessarily limited to about two or three hours after
school hours, the corridors and play rooms being cleaned during
the school period and only the class rooms being cleaned after
closing time.
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114
VACUUM CLEANING SYSTEMS
Let us assume, as an example, an ofQce building having eight
floors each 100 ft. x 150 ft., with a floor plan as shown in
Fig. 61.
The corridors, stairs and elevator halls will probably be
floored with marble which must be scrubbed in order to remove
the stain accumulated during the day and they will not be con-
sidered in connection with a dry vacuum cleaning system. The
area of the floors in the offices on any floor will be approximately
10,000 sq. ft. and one floor can be cleaned by one operator in
5 hours, or two floors during the cleaning period, so the plant
must be of sufficient size to serve four sweepers simultaneously.
FIG. 61. TYPICAL FLOOR PLAN OF OFFICE BUILDING ILLUS-
TRATING NUMBER OF SWEEPERS REQUIRED.
In a school house containing four class rooms, where the
janitor cleans the play rooms and corridors during the school
period, as can be readily done with a vacuum cleaner since
there will be no dust scattered about to fill the air and render
it unsanitary, the class rooms can easily be cleaned in one hour
by one operator. The author considers that one sweeper capac-
ity for each six to eight rooms is ample for a large school.
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PIPE AND FITTINGS 115
Buildings of special construction and used for special pur-
poses must be considered differently according to the conditions
to be met, but the size of the plant can be readily determined
in each case by use of the rules already given.
Number of Risers to be Installed. — Much difference of
opinion exists among the various manufacturers of vacuum
cleaning systems as to the maximum length of hose that should
be used with a cleaning system, and as this maximum length
determines the number of risers to be installed, some fixed
standard is necessary. As already stated in Chapter VI, the
author considers that this maximum ^ould be fixed at 75 ft. ;
that is, the risers should be so spaced that all parts of the fioor
of the building can be reached with 75 ft. of hose. Where 50
ft. is used as a maximum, as is recommended by many manu-
facturers, the number of risers would be increased, incurring a
greater cost of installation and requiring the operator to shift
his hose from one inlet to anottier more often than would be
the case where fewer inlets were used, and more time would
be required in cleaning, with a slight reduction in the power.
The author does not consider that this reduction in power would
be sufScient to offset the additional time required to change
the hose from one inlet to another.
The best and quickest way to determine the number of risers
necessary is to cut a piece of string to the length repre-
senting 75 ft. on the scale of the plans, and by running this
around the plan using corridor doors for access to all rooms,
wherever possible, locate the riser so that every point can be
reached with the string. In the case of the building illustrated
in Fig. 61 four risers located as shown will be necessary.
Size of Risers. — Before we can determine the size of risers
to be installed it is necessary to determine the probable num-
ber of sweepers that will be attached to any one riser simul-
taneously. In the case of the building (Fig. 61) it is possible
that there may be four sweepers attached to one riser and it is
also possible that there may be but one, and two sweepers to
a riser is considered to be a safe assumption. The author uses
the following rule in determining the size of risers to use :
Where the number of sweepers is double the number of risers,
assume that all sweepers will be on one riser simultaneously.
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116 VACUUM CLEANING SYSTEMS
Where the number of sweepers is equal to the number of
risers, assume that half the sweepers will be on one riser
simultaneously.
Where the number of sweepers is half the number of risers,
assume that one-quarter of the sweepers will be on one riser
simultaneously.
When no lifts occur a low velocity in the riser is not objec-
tionable and the size of the riser should be mjade equal to the
size of the horizontal branch thereto throughout its length,
wherever this branch is not larger than 2^4 in. diaaneter. When
larger, reductions in the riser can be. made until 2^ in. is
reached when this size should be maintained throughout the
remainder of its length. No riser should be made less than
2J^ in. unless a lift is necessary.
Before finally fixing the size of riser to be used in any
case the size of the branch in the horizontal lines serving the
same, must be approximately determined.
These sizes will be dependent on the location in which it is
necessary to install the vacuum producer. In the case of the
building (Pig. 61) the most desirable location for the vacuum
producer will be in the exact center of the building.
With the vacuum producer centrally located the longest run
from any riser will be 55 ft. To this we must add :
5 ft. for each long-turn elbow.
10 ft. for each short-turn elbow.
10 ft. for entrance to each long sweep Y branch.
20 ft. for entrance to a tee branch, except at sweeper inlets
on risers, where 10 ft. is ample
In calculating the riser friction for risers under 150 ft. in
length the whole capacity of the riser can be assumed as being^
connected to a point midway of its length.
In the eight-story building (Fig. 61) the length of the riser
from basement ceiling to eighth floor will be 100 ft. and the
length to be figured, 50 ft. The equivalent length of pipe line
for any of the risers, with the vacuum producer centrally
located, will be:
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PIPE AND FITTINGS 117
From entrance tee into riser 10 ft.
Length of riser, one-half total length 50 ft.
Turn at base of riser 10 ft.
Run in basement 55 ft.
Y branch or elbow 10 ft.
Elbow at separator 5 ft.
. Equivalent length 140 ft.
Each riser is to serve two sweepers and must pass 140 cu. ft.
of free air per minute. This will give a friction loss in a
2^ -in. pipe of 2 in. mercury, if 10 in. mercury be maintained
at the hose cock and 1-in. hose used ; and 1.5 in. mercury if 6 in.
mercury be maintained at the hose cock and lj4-in. hose used.
Either of these figures are within the limits set for the maxi-
mum friction, loss and 2j4-in. pipe will be the proper size
for the risers and their branches in the basement.
The portion of the main in the basement that serves the two
risers on either side of the building (portion **ab," Fig. 61)
must be of such size as will produce the same loss in vacuum
with 280 cu. ft. of air passing as the 2>^-in. pipe gives with
140 cu. ft. of air passing. This may be determined from any
table of equalization of pipes or may be obtained from the
chart. Fig. 48, in the following manner:
Find the intersection of the horizontal line **140" with the
diagonal representing a 2j4-in. pipe and pass on the nearest
vertical to its intersection with the horizontal line *'280." The
diagonal inclined toward the left passing nearest this intersection
will be the pipe size required. In this case a 3-in. pipe will
give a slightly greater friction and will be sufficient.
Unfortunately, it is rarely possible to locate the vacuum pro-
ducer in as favorable a point as that given in the illustration,
but an effort should always be made to select a location as
nearly central to all risers as possible. The basements of mod-
em office buildings are generally crowded and the space assigned
to the mechanical equipment is limited and owing to the neces-
sity of ventilation, the vacuum producer is generally located
near the outside of the building.
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118
VACUUM CLEANING SYSTEMS
Probably the best location that could be obtained in this ease
would be at ''d" (Fig. 62). The length of piping to risers 1
and 2 would now be the same as that to all risers in case of
Fig. 61, but the distance to risers 3 and 4 will be increased 50
ft. It will be possible to increase the size of the pipe line
**bd" to the maximum size to serve four sweepers, or 3^ in.,
the risers and their branches to remain 2^ in.
The total friction loss to risers 1 and 2 will now be:
Entrance to tee in risers, 10 ft. plus 50 ft 60 ft.
Turn at base of riser, 10 ft., branch from *'c''
to riser 32 ft 42 ft.
Entrance to tee in main 20 ft.
122 ft.
Total equivalent length of 2^ -in. pipe .
When 1-in. hose is used the density of the air entering the
2j4-in. pipe is equivalent to a vacuum of 10 in. mercury and
the friction loss in the 25^-in. pipe will be 1.9 in. mercury.
•4
^r
^>
^r
•h
^r
3/'
ii'
z
(
•?
PIG. 62. ELEVATION OP LAYOUT POR OPPICE BUILDING, SHOWING
BEST LOCATION (AT D) FOR VACUUM PRODUCER.
When Ij^-in. hose is used, the density of the air entering the
pipe will be equivalent to a vacuum of 6-in. mercury and the
friction loss in the 2>4-in. pipe will be 1.32 in. mercury.
The density of the air entering the 3>4-in. pipe, **b d,'' will
be equivalent to a vacuum of 11.9 in. mercury when 1-in. hose
is used, and to 7.32 in. mercury when 1^-in. hose is used.
The friction loss in the 3>4-in. pipe will be 0.31 and 0.23 in*
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PIPE AND FITTINGS 119
mercury, respectively. Total friction loss to inlets on risers.
1 and 2 will be 2.21 in. with 1-in. hose in use, and 1.55 in. with
1J4-U1. hose.
To obtain the friction loss to inlets on risers 3 and 4 the
friction loss in the pipe '*bc" must be added to the above
figures. With 50 ft. of 3j^-in. pipe carrying 280 cu. ft. free
air the friction loss is 0.6 in. when the vacuum in the pipe is
12 in. and 0.4 w<hen the vacuum in the pipe is 8 in.
The total loss of vacuum to inlets on risers 3 and 4 will be 2.91
in. if 1-in. hose is used and 1.95 in. if Ij^-in. hose is used. In
this case, the total loss from inlet to vacuum producer is ap-
proximately equal to the maximum variation of vacuum per-
mitted at sweeper outlets when 1,34 -i^- h<>se is used, but is
greater than when 1-in. hose is used.
However, it is the variation in vacuum at the hose cock
farthest from and that nearest to the vacuum producer that
fixes the maximum variation allowable. In this case it will be
the difference in vacuum between an inlet on riser 1 or 2 and a
similar inlet on riser 3 or 4. The difference in vacuum at the
bases of these risers will be the friction loss in the pipe **bc,"
and the total difference in friction in the risers will occur when
one sweeper is attached to the lowest inlet on one riser, and
one sweeper on the eighth and one on the seventh floor on the
other riser. The friction loss in the riser having the two
sweepers attached to its upper inlets will be :
15 ft. of 23/^-in. pipe from seventh to eighth floors, 70 cu. ft.
of free air per minute, or 0.051 in. with a density equivalent
to 6-in. vacuum, and 0.075 in. with a density equivalent to 10-
in. vacuum.
85 ft. of 23^ -in. pipe from first to seventh floors, 140 cu. ft.
free air per minute, or 0.25 in. with a density equivalent to
6-in. vacuum, aild 0.42 in. with a density equivalent to 10-in.
vacuum.
The total difference in vacuum at the hose cocks will be :
0.051-|-0.25-f-0.4=0.7 in. with 6-in. vacuum at the hose cock.
0.075-f0.42-f0.6=1.15 in. with 10-in. vacuum at the hose cock.
Either of these values are well within the maximum varia-
tion. It is, therefore, evident that when the vacuum producer
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120 VACUUM CLEANING SYSTEMS
cannot be centrally located that a piping system which will
give the most nearly equal length of pipe to each riser will
yield the best results.
A vacuum cleaning system for serving a passenger car stor-
age yard will best illustrate the effect of long lines of piping.
A tjrpical yard having 8 tracks, each of sufficient length to
accommodate 10 cars, is shown in Pig. 63. The vacuum pro-
ducer in this case is located at the side of the yard at one end,
which is not an unusual condition.
The capacity of this yard will be 80 cars which must gen-
erally be cleaned between the hours of midnight and 6 A. M.,
or a period of 6 hours for cleaning.
It will require one operator approximately 20 minutes to
thoroughly clean the floor of one car, on account of the difficulty
in getting under and around the seat legs. In addition to this,
it is also necessary to clean the upholstery of the seats and their
backs, which will require approximately 25 minutes more or
45 minutes for one operator to thoroughly clean one car.
Therefore, one operator can clean 8 cars during the cleaning
period and a ten-sweeper plant will be necessary to serve the
yard.
One lateral cleaning pipe must be run between every pair of
tracks or four laterals in all to properly reach all cars without
running the hose across tracks where it might be cut in two
by the shifting of trains.
Outlets should be spaced two car lengths apart in order to
bring an outlet opposite the end of every second car. This will
make it possible to bring the hose in through the end of the
car at the door opening and clean the entire car from one end
which can be done by using 100 ft. of hose. The use of double
the number of outlets and 50 ft. of hose would require two at-
tachments of the hose to clean one car resulting in a loss of
time in cleaning and is not recommended.
In this case, 100 ft. of hose would be the shortest length that
would be likely to be used and 60 cu. ft. of free air would be the
maximum to be allowed for when using lj4-in. hose.
The simplest layout for a piping system to serve this yard
would be that shown in Pig. 63.
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PIPE AND FITTINGS
121
When the entire yard is filled with ears and the entire force
of ten operators is started to clean them it would be possible to
so divide them that not over three operators would be working
on any one lateral and this condition will be assumed to exist.
The maximum size for the laterals between the tracks will be
that for three sweepers, or 3 in., and it will not be safe to use
this size beyond the second inlet from the manifold, from which
point to the end of the lateral it must be made 2j4 in., the
maximum size for either one or two sweepers. The total loss
of pressure due to friction from the inlet at x (Pig. 63) to
the separator can be readily calculated from the chart (Pig.
56) as follows:
TABLE 20.
Pressure Losses from Inlet to Separator in Svstem for Cleaning
Railroad Cars.
Average
•
Equiv-
Vacuum
Friction
Final
Cubic Ft.
alent
Size of
Ins.
Loss,
Vacuum,
Section
Free Air
Length,
Pipe,
Mer-
Ins.
Ins.
of Pipe.
per min.
feet.
In. Diam.
cury.
Mercury.
Mercury.
x-5
60
150
2H
6
0.35
6.35
5-4
120
140
2V2
7
1.35
7.70
4—2
180
280
2V2
11
7.0
14.70
2— w
180
190
3
16
4.0
18.70
w— u
360
20
5
19
0.9
19.60
u— s
480
20
6
20
0.5
20.10
s— Sep
600
20
6
20
0.4
20.50
This loss will be the maximum that is possible under any
condition as it is computed with three sweepers working on the
three most remote inlets on laterals **xy" and '*vw" and with
two sweepers on laterals **tu" and **rs." The pipes are the
largest which will give a velocity of 40 ft. per second with the
full load and at the density which will actually exist in the
pipe lines with the vacuum maintained at the separator of
20 in. mercury in all cases, except the pipe from **s'' to sepa-
rator. There the size was maintained at 6 in., as it was not
considered advisable to increase this on account of the reduced
velocity which would occur when less than the total number of
sweepers might be working.
As bare floor brushes will be used for cleaning coaches it is
not considered advisable to reduce the air quantity below that
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122 VACUUM CLEANING SYSTEMS
required by such renovators. However, when carpet renovators
are used in Pullman ears and upholstery renovators are used
on the cushions of both coaches and Pullmans, the air quantity
will be reduced. This condition may exist at any time, also
one of these carpet or upholstery renovators may be in use on
one of the inlets most remote from the separator at the same
time that nine floor brushes are in use on the remaining out-
lets. In that case a vacuum at the separator of less than 20 in.
would result in a decrease in the vacuum at the inlet to which
this renovator was attached. The vacuum at the separator must,
therefore, be maintained at the point stated.
— .16.6 0- ^i - ^rack'4
T
._ I 7/wrA»/
IS m: \ a: -f if i u' ylx
51
-if ■ ^r ■ H' , g£:
TnrcA^
■i—
TiW -^ Tnxk'6
1^00'
TnacA^
^20.50'
Oheparator
I9S0
PIG. 63. VACUUM CLEANING LAYOUT FOR A PASSENGER CAR
STORAGE YARD.
With such a vacuum there will be variation in the vacuum
at the hose cocks of from 6 in. to 20 in. or seven times the
maximum allowable variation in vacuum at the hose cocks.
If 1-in. hose be used, the maximum air quantities will be 40
cu. ft. per sweeper If we start with a vacuum at the inlet
**x'' of 10-in. mercury, the vacuum at the separator will again
be 20 in. and we now have a variation of 10 in. between the
nearest and most remote inlet from the separator, or five times
the maximum allowed.
Either of these conditions is practically prohibitive, due to :
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PIPE AND FITTINGS
123
1. The excessive power consumption at the separator. 50 H. P.
in case lj4-iii- hose is used, and 33 H. P. in case 1-in. hose
is used.
2. The excessive capacity of the exhauster in order to handle
the air at such low density, a displacement of 1,800 cu. ft.
being necessary in case lj4-in. hose is used and 1,200 cu. ft.
in case 1-in hose is used.
3. The great variation in the vacuum at the hose cocks which
will admit the passage of so much more air through a brush
renovator on an outlet close to the separator as to render use-
less the calculations already made, or the high vacuum at the
carpet or upholstery renovators would render their operation
practically impossible.
^
>»-
IP '^__ ^4^
-jL
351
r *fe Track* I
^
=5^'"
3'
Track *2
Track *3
Track U
Track *5
Track •e
Track *7
i
Track ''6
%^ KSOmfh/'Hoie
FIG. 64. ARRANGEMENT OP PIPING RECOMMENDED AS BEST FOR
PASSENGER CAR STORAGE YARD.
Such a layout must be at once dismissed as impractical, and
some other arrangement must be adapted. The arrangement of
piping shown in Fig 64 is considered by the author to be the
best that can be devised for this case.
With this arrangement the vacuum at the separator must be
maintained at 11.50 in. mercury to insure a vacuum of 6 in.
mercury at the outlet **x" under the most unfavorable con-
ditions, and the maximum variation in vacuum at the inlets will
be 3.45 in. mercury when lj4-in. hose is used. This will give
a maximum vacuum under a carpet renovator of 7^/2 in. raer-
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124 VACUUM CLEANING SYSTEMS
cury with 37 cu. ft. of air passing and will permit 70 cu. ft.
of free air per minute to pass a brush renovator when operating
with 100 ft. of hose attached to the inlet at which the highest
vacuum is maintained. Both of these conditions will permit
satisfactory operation and the increased air quantities will not
seriously aflfect the calculations already made. The maximum
horse power required at the separator will now be 20.5 as
against over 50 in the case of the piping arrangement shown in
Fig. 63, and will require an ex!hauster having a displacement of
950 cu. ft. instead of 1,800 cu. ft. required with the former
layout.
If 1-in. hose is used and 10 in. mercury maintained at the
outlet **x" under the same conditions as before, the vacuum
at the separator will be 14.50 in. and the maximum variation
in the vacuum at the inlets will be 3 in., which will give a
maximum vacuum under a carpet renovator of 6 in. mercury
with 32 cu. ft. of air passing and will permit the passage of
45 cu. ft. of free air through a brush renovator when operated
at the end of 100 ft. of hose attached to the outlet at which
the highest vacuum is maintained. This is a more uniform re-
sult, than was noted when V/^-in, hose was used.
The maximum horse power which will be required at the
separator will now be 18.6 and the maximum displacement in
the exhauster will be 740 cu. ft.
It is, therefore, evident that, where very long runs of piping
are necessary and where 100 ft. of hose will always be necessary,
the use of 1-in. hose will require less power and a smaller dis-
placement exhauster than would be required with lj4-in. hose,
without affecting the efficiency of the cleaning operations, and
at the same time rendering the operation of the renovators on
extreme ends of the system more uniform.
The example cited in Figs. 63 and 64 is not by any means an
extreme case to be met in cleaning systems for car yards, and
the larger the system the greater will be the economy obtained
with 1-in. hose.
Such conditions, however, are confined almost entirely to lay-
outs of this character and will seldom be met in layouts within
any single building. This is fortunate, as the train cleaning is
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PIPE AND FITTINGS
125
practically the only place where the use of 100 ft. of hose can
be assured at all times.
Very tall buildings offer a similar condition although the
laterals are now vertical and can be kept large enough to suf-
ficiently reduce the friction without danger of deposit of dirt
in them, and the horizontal branches will be short and also
large enough to keep the friction within reasonable limits with-
out danger of deposit of dust.
Where large areas within one or a group of buildings must
be served by one cleaning system, better results can often be
obtained by installing the dust separator at or near the center
of the system of risers instead of close to the vacuum producer,
as indicated in Fig. 65. When this is done, the pipe leading
beparafor
Clean Air Une
CH
PIG. 65. GOOD LOCATION FOR DUST SEPARATOR WHERE LARGE
AREAS ARE SERVED BY ONE CLEANING SYSTEM.
from the separator to the vacuum producer carries only clean
air and can be made as large as desired and the friction loss re-
duced, resulting in a considerable reduction in the power re-
quired to operate the system.
Where the system becomes still larger, two or more separators
located at centers of groups of risers can be used and clean
air pipes of any desired size run to the vacuum producer (Fig.
66). When more than one separator is used care should be
exercised in proportioning the pipe lines from the separators
to the vacuum producer so as to have the friction loss from the
vacuum producer to each separator the saime in order to
give uniform results at all inlets. This loss should also be
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126
VACUUM CLEANING SYSTEMS
kept as low as possible in order to prevent a higii vacuum
in a separator serving a portion of the system on which feV
sweepers are in operation. If low friction losses in the clean air
pipe will require larger pipes than it is practical or economical
to install, pressure reducing valves might be located in the
clean air pipes near the separators to so regulate the vacuum
at the separators and insure uniform results. A system of this
kind might serve several premises and the air used by each be
metered and the service sold much the same as heat and elec-
tricity. However, the power required to operate the system
would be greater than that needed to operate a similar num-
-o— — e
F
01
-i8-
CleanAirLine
4
czi
FIG. 66. LOCATION OP SEPARATORS AT CENTERS OP GROUPS OP
RISERS FOR LARGE SYSTEMS.
ber of sweepers by individual plants owing to the higher vac-
uum required to overcome the friction in the trunk mains.
This would be offset by the use of larger units and the possi-
bility of operating them at full load at nearly all times. A
system of this kind was contemplated in Milwaukee some seven
years ago, but was never installed.
The question of pipe friction in connection with the design
of vacuum cleaning systems requires careful consideration,
much more than it ever received in the early days of the art
and a great deal more than it sometimes receives at the present
time.
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CHAPTER VIII.
Separators.
The appliances which remove the dust from the air current
which has carried it through the hose and pipe lines, in order
to prevent damage to the vacuum producer, play an important
part in the make-up of a vacuum cleaning system.
Classification of Separators. — Separators may be divided in-
to two classes according to their use:
1. Partial separators, which must be used in conjunction with
another separator in order to effect a complete removal of the
dust from the air. These separators are again divided into
two sub-classes, i, e., primary, or those removing the heavy
particles of dust and dirt only, and secondary, or those re-
moving the finer particles of dirt which have passed through the
primary separator.
2. Complete separators, or those in which the removal of both
the heavy and the finer particles of dust is effected in a single
separator.
Separators may also be classified, according to the method
employed in effecting the separation, into dry separators in
which all operations are effected without the use of liquid, and
wet separators in which water is employed in the removal of
the dust.
Primary Separators. — Primary separators are nearly always
operated as dry separators and depend largely on centrifugal
force to effect the separation. The first type of primary sepa-
rator used by the Vacuum Cleaner Company is illustrated in
Fig. 67. This consists of a cylindrical tank, with hopper bottom,
containing an inner cylinder fixed to the top head. The dust-
laden air enters the outer cylinder near the top on a tangent
to the cylinder. The centrifugal action set up by the air strik-
ing the curved surface of the outer cylinder tends to keep the
127
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128
VACUUM CLEANING SYSTEMS
heavy dirt near the outside of same, and as it falls towards the
bottom the velocity is reduced and its ability to carry the dust
is lost. When the air passes below the inner cylinder the veloc-
ity is almost entirely destroyed and all but the very lightest of
the dust particles fall to the bottom, while the air and the light
dust particles find their way out of the separator through the
opening in the center at the top.
^
=e
PIG. 67. EARLY TYPE OP PRI-
MARY SEPARATOR, USED BY
VACUUM CLEANER COMPANY.
FIG. 68. PRIMARY SEPARATOR
USED BY THBS SANITARY DE-
VICES MANUFACTURING COM-
PANY.
The primary separator used by the Sanitary Devices Manu-
facturing Company is illustrated in Fig 68. The inner cen-
trifugal cylinder is omitted and the air enters through an elbow
in the top of the separator, near its outer extremity, which is
turned at such an angle that the air is given a whirling motion
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SEPARATORS
129
resulting in the dust being separated much the same as in the
case of the Vacuum Cleaner Company's apparatus.
Either of these separators will remove from 95% to 98%
of the dirt that ordinarily comes to them through the pipe lines
and are about equally efficient.
The separator illustrated in Fig. 69 was used by the General-
Compressed Air and Vacuum Cleaning Company. The enter-
ing air is led to the center near the bottom and is then released
through two branches curved to give the air a whirling motion.
The clean air is removed from the center of the separator near
PIG. 69. PRIMARY SEPARATOR
USED BY THE GENERAL COM-
PRESSED AIR AND VACUUM
CLEANING COMPANY.
FIG. 70. PRIMARY SEPARATOR
MADE BY THE BLAISDELL
ENGINEERING COMPANY.
the top. This separator is not as effective in its removal of dirt
as either of the former types, owing ix) the entering air
being introduced near the bottom This tends to keep the air
and the dust in the bottom of the separator continually stirred
up, also the curved inlets give the air more of a radial than a
tangential motion and there is less separation due to centrifugal
action.
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130 VACUUM CLEANING SYSTEMS
The separator illustrated in Fig. 70 is made by the Blaisdell
Engineering Company. In this separator the inner centrifugal
cylinder of the Vacuum Cleaner Company's separator is re-
placed by a spiral extending nearly to the outlet in the center
of the top. This arrangement tends to prevent the reduction in
the air velocity and to limit its effectiveness in the removal
of dust.
Separators similar to the Sanitary separator have been manu-
factured by many firms producing vacuum cleaning systems.
These all differ somewhat in details of construction but the
principle involved, i. e,, centrifugal force and reduction in air
velocity, is the same in all cases.
With vacuum producers in which there are no close clear-
ances or rubbing contacts, these are the only separators used.
The finer particles of dust passing these separators are carried
harmlessly through the vacuum producer and through the ex-
haust to the outer atmosphere or to the chimney or other flue
where they are effectively sterilized.
Secondary Separators. — With vacuum producers having
close clearances or rubbing parts in contact with each other and
the air exhtausted, further separation of the finer dust particles
is necessary. To accomplish this, secondary separators are used.
All of the early systems used a wet separator as a secondary
separator. That used by the Vacuum Cleaner Company is illus-
trated in Fig. 71. It consists of a cylindrical tank partially
filled with water, with a diaphram perforated in the central
portion and fixed in place below the water line, and an inverted
frustrum of a cone placed just above the water line. The air
enters the separator below the water line and passes up through
the water in the form of small bubbles which are broken up into
still smaller bubbles on passing through the perforations in
the diaphram. This action is very essential to the thorough
cleansing of the air, as large bubbles of air may contain en-
trapped dust which will pass through the water and out into
the vacuum producer. The inverted frustrum of a cone is in-
tended to prevent any entrained water passing out of the sepa-
rator with the air. This separator has always given satisfactory
results when used in connection with reciprocating pumps.
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SEPARATORS
131
The separator illustrated in Fig. 72 was manufactured by the
General Compressed Air and Vacuum Cleaning Company. The
air enters the separator through the pipe curved downward and
escapes at the center below the water line. It then rises in the
form of bubbles and most of it strikes the under side of the
ribbed aluminum disc **a," which is intended to float on the
surface of the water, and passes along the ribbed under surface
of this; disc, escaping into the upper part of the separaitor around
the edge.
The clean air passes out of the top of the separator to the
vacuum producer. The successful operation of this separator is
W aUrL'mt^ ^
FIG. 71. SECONDARY SEPARA-
TOR USED BY THE VACUUM
CLEANER COMPANY.
PIG. 72. SECONDARY SEPARA-
TOR USED BY THE GENERAL
COMPRESSED AIR AND
VACUUM CLEANING COMPANY.
dependent on the freedom of motion of the disc **a," which will
always keep it on the surface of the water, and on all of the
air passing up through* the water under the disc.
Should the disc become caught on the supporting pipe the
violent agitation of the water, which occurs when the system
is in operation, will cause the disc to be left high and dry above
the water at times, and submerged at other times. When this
disc is above the water line it will not break up any of the
large bubbles. Also, when there is a large quantity of air pass-
ing through the separator, there is great likelihood that con-
siderable of the air bubbles will pass up through the water en-
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132
VACUUM CLEANING SYSTEMS
tirdy outside of the disc and these 't)ubbles will not be broken
up. This separator has given somewhat unsatisfactory results in
some installations tested by the author.
The separator used by the Sanitary Devices Manufacturing
Company differs from those already described in that the air
and water are mixed before they enter the separator and the
air comes into the separator above the water line. The air enters
the pipe **a" (Fig. 73) and passes to the aspirator **b,'' which
is connected to the separator by the pipe *'d" below the water
line and the pipe **e'' above the water line. The excess of
vacuum in the separator draws tlhe water out of the aspirator
n=^
FIG. 73.
SECONDARY SEPARATOR USED BY THE SANITARY DEVICES
MANUFACTURING COMPANY.
and its pipe connections until the water line in this pipe
is lowered below the top of the horizontal portion of the
piping, when the air bubbles up through the demonstrator
glass **c" and passes into the separator through the pipe **e.''
The filling of the vertical pipe leading to **c" with air causes
the static head of the water in the separator to produce a flow
of water through the pipe ''d'* into the aspirator **b." This
is formed in the shape of a nozzle and the water enters in the
form of a spray and thoroughly mixes with the air. The cleans-
ing action of this water spray has been found to be very
effective in removal of all fine dust and this separator has been
found to be the most effective wet separator ever produced.
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SEPARATORS 1^3
While the wet separator when properly designed will effective-
ly remove the finest of dust, greasy soot will not emulsify with
the water and its removal is practically impossible. Fortu-
nately, this form of material in the finely-divided condition in
which it passes the primary separator is not gritty and does not
produce injurious effect on the vacuum producer.
The wet separator is also ait a disadvantage in that there is a
loss of vacuum in passing through same equal to the head of
water that is carried between the inlet and the surface of the
water. This generally amounts to nearly 2 in. mercury.
Means must be provided to observe the height of the water
in the wet separator. For this purpose a glass window in the
side of the separator has been found to be the most effective.
The use of an ordinary gauge glass such as is used on boilers
has been tried, but it has been found that they readily become
so clouded by the action of the muddy water as to render them
useless while the constant agitation of the water against the
window when the system is in operation tends to keep the
glass clean.
Dry separators have been used for secondary separators to
a limited extent. All of these contained a bag made ef canvas
or some other fabric. The separator illustrated in Fig. 74 con-
tains a bag made of drilling which is slightly smaller than the
inner diameter of the cylindrical casing of the separator. The
air enters the inside of the bag, inflating it, and passes through
the bag and out through the opening in one side of the casing.
A wire guard is placed over this opening to prevent the bag
being drawn against the opening and thus rendering only a
small jwrtion of it effective.
These bags offer very little resistance to the passage of the
air when they are clean but they soon become filled with dust
and produce an increased resistance which, if neglected, may
result in so great a difference in pressure as to hinder the action
of the system and result in the rupture of the bag, letting the
dust into the vacuum producer.
Some trouble has been experienced in finding a suitable ma-
terial through which the dust will not pass. Hush ddth, such as
used on dining tables, has been found to be the best material
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134
VACUUM CLEANING SYSTEMS
for this purpose. Better results are obtained by passing the
air from tiie outside of the bag towuds the inside than when
the air is paesed as indicated in Fig. 74. When this arninge-
menrt is adopted, it is necessary to stretch the bag oyer a metal
screen or frame in order to prevent collapse.
Complete Separators. — Complete separators are of two classes,
t. e., dry and wet The first complete separator that the antbor
has knowledge of was nsed hy tiie Yacunm Cleaner Company,
in tilie form of a cylindrical tank and contained centrifugal
cylinder and also a perforated plate. It was practically a com-
bin»ti(Mi of the sqparators indicated in Figs. 67 and 71. This
separator was installed in connection with a small rotary pump
hJ
J
hnhrnnmrninTrr
PIO. 74. TYPB OF DRY SEPARATOR USED AS SECONDARY SEPARATOR.
and mouDited on a truck. It worked very weU until it beoame
filled with dirt when, in one case, the entire contents were
ejected into an apartment in which it was being used. This
separator was then rebuilt in the form shown in Pig. 75, the
bag being made of hush cloth stretched over a wire screen. The
air enters the cylinder tangentially and much of the separa-
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SEPARATOES
135
tion is accomplished by centrifugal force, the remainder of the
dust being removed as the air passes through the bag. This
separator was successfully used as long as this company con-
tinued to manufaoture such apparatus.
Another form of complete separator quite similar to that
above described has recently been brought out by the Electric
Renovator Manufacturing Company and is shown in section in
Fig. 76. The air enters this separator tangentially below the
line of the dust bag, which is made of muslin folded back and
forward over a set of concentric cylinders thus giving a large
area for the passage of the air. Being entirely above the line
of the entering air, none of the heavy dirt strikes the bag
and what dirt is eaugbt on the bag is on the lower side of same
and is shaken off every time the bag is agitated. This agitation
PIG.
75. FORM OP COMPLETE SEPARATOR USED BY THE VACUUM
CLEANER COMPANY.
occurs every time there is any change in the volume of air
passing the separator, and when these separators are used in
connection with fan type of exhausters there is a constant surg-
ing whenever the exhauster is operated with a small volume of
air passing. This tends to keep the bag clean automatically.
The separator illustrated in Fig. 77 is manufactured by the
American Radiator Company. The air enters this apparatus
through the pipe in the center and passes directly down to the
bottom, the velocity being gradually reduced due to the ex-
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136
VACUUM CLEANING SYSTEMS
pansion of the air as it passes down the cone-shaped inlet, the
heavy dirt falling to the bottom. The air then passes up along
PIO. 76.
COMPLETE SEPARATOR BROUGHT OUT BY THE ELECTRIC
RENOVATOR MANUFACTURING COMPANY.
the inner surface of the cylindrical shell and thence through the
bag, which is stretched over a screen, to the outlet. In this
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SEPARATORS 137
separator we see the first case in which centrifugal action is not
utilized in separating the heavy dust, the makers evidently con-
FIG. 77. COMPLETE SEPARATOR MADE BY THE AMERICAN RADIATOR
COMPANY.
sidering the reduction of air velocity and the action of gravi-
tation to be ample. This bag is arranged to permit the air
passage from the outside towards the inside and it is tapered
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138 VACUUM CLEANING SYSTEMS
to allow the dirt to fall off. The vacuum gauge is connected
to the inner and outer sides of the bag by means of a three-way
cock to permit of measuring the difference in vacuum between
the inside and outside of the bag to determine when the bag is
in need of cleaning, which is accomplished by a reversal of the
air current through the bag. This is quite necessary in order to
keep the separator always in an efficient condition.
A separator was devised by the. Sanitary Devices Manufac-
turing Company in which the bag was held extended by a wire
ring having a weighted rod passing out through the top of the
separator attached thereto. When the bag became clogged the
difference in pressure on the two sides would result in a tend-
ency of the bag to collapse and the rod would be raised up
out of the separator, indicating that cleaning was necessary,
which could be easily accomplished by drawing the rod up and
down a few times thus shaking the dust off the bag. This
separator never came into general use, although its arrangement
was ingenious and should have been easy to operate.
The great difficulty with all bags which must be cleaned
periodically is that they are almost universally neglected even
when there is a visual indicator to show the accumulation of
dirt, and when it becomes necessary to manipulate a three-way
cock in order to ascertain when this cleaning must be done it
will seldom if ever be attended to. A bag that will clean itself,
such as the Capitol Invincible, is shown in Fig. 76.
The separator used by one manufacturer consists of a simple
cylindrical tank into which the air is blown tangentially, with
a screen near the top, the whole forming a base for the vacuum
producer. This separator does not remove any but the heaviest
dirt and is suitable for use only with a vacuum producer having
very large clearances and in locations where the discharge of
considerable dirt into the atmosphere is not objectionable.
Total Wet Separator. — The only total wet separator which
is in commercial use is manufactured by the American Rotary
Valve Company. This separator is contained in the base of the
vacuum producer and is provided with a screen near the point
of entrance of the dust-laden air, which screen is cleaned by a
mechanically-driven bristle brush. When the water in the
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SEPARATORS 139
separator becomes foul, the contents of the separator are dis-
charged direct to the sewer by means of compressed air. If
this separator receives proper attention it makes the most sani-
tary arrangement that has been introduced in the vacuum
cleaning line to date. However, the separator should be emptied
at frequent intervals or the volume of solid matter contained in
the same will become so great that there will not be enough
water present to flush the sewer and stoppage is likely. These
separators are often neglected until the contents become of the
consistency of mortar or molasses which is not a fit substance
to discharge into a sewerage system.
There is still another form of apparatus used in connection
with vacuum cleaning systems which should be called an emul-
sifier rather than a separator. That is the type used with the
Rotrex and the Palm i^stems. The dust is mixed with water
when it first enters the pump chamber, a screen being used to
remove the lint and larger particles of dirt and then the mud
produced by thei combination of the dust and water is passed
through the pump along with the air. The air and muddy
water are separated on the discharge side of the vacuum pro-
ducer. In many cases where the exhaust pipe is long, there is
considerable back pressure on the discharge which is often suf-
ficient to force the seals in traps on the sewerage syntem, allow-
ing sewer gas to be discharged into the building in whioh the
cleaning system is installed. No means are provided for auto-
matically cleaning the screen used in these appliances and the
author knows of cases where the screen has become so com-
pletely clogged with lint that its removal from the machine was
necessary in order to render the operation of the cleaning tools
possible.
When dry separators are used, the manual removal of the dry
dirt accumulated is necessary and is an objectionable as well as
unsanitary operation. The author considers that the ideal
arrangement of separator would be one in which the dirt can
all be emulsified with water and retained in the separator, only
the air passing through the vacuum producer, and in which the
contents of the separator would be discharged automatically to
the sewer when the density of this mixture becomes as heavy as
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140 VACUUM CLEANING SYSTEMS
will readily run through the sewer. This discharge should be
of sufficient volume to completely fill an ordinary house sewer
in order to insure a thorough flushing of the drain, and should
be discharged into the sewer under atmospheric pressure in
order to guard against the forcing of water seals in any of the
plumbing fixtures.
FIG. 77a. INTERIOR CONSTRUCTION OF DUNN VACUUM CLEANING
MACHINE.
A separator of this type has recently been patented by E. D.
Dunn, originator of the Dunn Locke system. It is illustrated in
Fig. 77a. The action of the separator is as follows: After
starting the motor and turning on a small quantity of water,
a vacuum is produced in one tank and through a system of
piping to the cleaning implement in use. The dust and dirt
collected by the implement is saturated as it approaches the
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SEPAEATORS 141
plant and in this saturated oondition enters the bottom of a
body of water in the tank.
When the accumulating dirt and water reach a certain level a
valve is automatically operated which closes the tank's commu-
nication with the vacuum pump and allows its contents to flow
off to the sewer by gravity. The mechanism for operating the
valve is rather unique and includes a float which, on rising
with the water, makes a positive electrical contact, as shown
in the figure. In this illustration one tank is about to dis-
charge and the other tank is about to become operative. The
electrical contact causes the core of the magnet at 0' to rise,
making the lever, K, turn over, which action opens one valve
and closes the other. In this way the tanks alternately partly
fill and empty their collections of water and sweepings.
This system has not as yet been in commercial use for
a sufficient length of time to insure its successful operation, and
the author does not consider the passing of dirt and water
through ordinary dheck valves to be commercially possible with-
out rendering these checks inoperative.
Check valves have been used where partial wet and dry
separators are operated in tandem to prevent drawing water
into the dry separator, in the event of the plant being shut
down with all inlets on the pipe line closed. In such a case,
the leakage through the pump into the wet separator may raise
the pressure in this separator faster than leakage on the pipe
line raises the pressure in the dry separator.
This is accomplished by providing a small connection between
the upper part of the two separators, fitted with a check valve
opening towards thf dry separator. When the vacuum pro-
ducer is in operation, the vacuum in the wet separator is
approximately 2 in. greater than that in the dry and the check
is held closed. When the vacuum producer is stopped and the
vacuum in the wet separator falls faster than in the dry sepa-
rator, this check opens and clean air passes from the wet to
the dry separator. When operating under these conditions, the
action of the check valve is satisfactory. However, the author
has known of cases where the check leaked and when this hap-
pened the check was immediately clogged by the dust-laden
air from the dry separator.
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CHAPTER IX.
Vacuum Pboduchers.
The next portion of the cleaning system is that which pro-
duces the motion of the air through the system and that to
which the motive power is applied, namely, the vacuum pro-
ducer.
Types of Vacuum Producers. — Vacuum producers can be
divided into general classes: 1. Displacement type, in which a
constant volume of air is displaced during eadh complete cycle
of operations of the machine, and 2. Centrifugal type, in which
the volume of air passing the producer during each complete
cycle of operations varies with the resistance to the passage of
such air through the system.
Displacement Type. — Under this head the piston aud rotary
pumps are classed, and they are subdivided according to con-
struction into reciprocating and rotary, valved and valveless,
air cooled and water cooled.
Centrifugal Type. — Under this (head the fan type of vacuum
producers are classed. They may be divided, according to
construction, into single stage and multi-stage, horizontal and
vertical.
Power Required to Produce Vacuum. — In order to ascer-
tain the efficiency of the various types of exhausters to be dis-
cussed in this chapter it is necessary to ascertain the actual
power necessary to move one cubic foot of free* air at any degree
of vacuum.
As nearly all machines tested by the author were driven by
electric motors and the power was, therefore, indicated in watts,
the curve C-D in Fig. 78 showing the actual power necessary to
exhaust one cubic foot of free air at the vacuum noted in the
lower margin, assuming no clearance and adiabatic compres-
sion, is used as a basis for calculation of efficiency. This shows
142
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VACUUM PRODUCERS
143
that to produce a vacuum of 8 in. mercury there will be re-
quired an expenditure of 16 watts for each cubic foot of free
air exhausteed, and to produce a vacuum of 12 in. mercury will
require an expenditure of 27 watts. If these quantities be
divided by the efficiency of the machine the actual power re-
quired will be determined.
40-
30
20
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Total Power Required to Drive Air Compfeasor
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PIG. 78. POWER CONSUMPTION AND EPPICIBNCY OP AIR COM-
PRJSSSOR USED AS A VACUUM PUMP.
Reciprocating Pumps. — The reciprocating pump was used
on the majority of the earlier vacuum cleaning systems. The
most common form in early use was a commercial air compressor
which was used as a vacuum pump withiout any change in its
construction. It was usually fitted with mechanically-operated
inducition and poppet type of eduction valves of heavy pattern,
.fiftted with cushions of the dash i>ot principle, the same as are
used on air compressors working against terminal pressures
as high as 100 lbs. per square inch. The cylinders were water
jacketed to remove the heat of high compression. The valves in
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144
VACUUM CLEANING SYSTEMS
these compressors were heavy and required considerable pres-
sure to open them and the friction of the valve gear and other
moving parts, which were made heavy enough to withstand the
strains of high compression, was excessively high for a machine
where the compression did not exceed 8 or 9 lbs. per square
inch. Their efficiency, therefore, is lower under actual operat-
ing conditions than if they were workiag against pressures for
which they were designed. A curve of the power consumption
of a 14-in. x 8-in. Clayton compressor is shown on Fig. 78,
the abscissae being the vacuuim in in<jhes of mercury and the
ordinates of curve ** AB'' the watts required to exhaust one cubic
FIG. 79.
MODIFICATION OF RECIPROCATING PUMP MADE BY THE
SANITARY DEVICES MANUFACTURING COMPANY.
foot of free air. Curve **cd" represents the theoretical watts
required to do the same work. These compressors were used in
connection with systems operating with 1-in. hose and the
vacuum usually carried was 15 in. mercury. They require ap-
proximately 77 watts per cubic foot of free air at this vacuum
and the efficiency, shown in curve **ce'' (Fig. 78) is 46%.
Were this compressor used in connection with a system oper-
ating through 1%-in. hose and a vacuum of 8 in. mercury main-
tained, the efficiency would drop to 31%.
A modification of the reciprocating pump was manufactured
by the Sanitary Devices Manufacturing Company in which
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VACUUIVI PRODUCERS
145
light-weigiit poppet valves plaxsed in the heads of the cylinder
were used, as indicated in Fig. 79. Curves of the watts per
cubic foot and efficiency of this type of compressor ar§ shown
in Fig. 80. It will be noted that this compressor shows a better
efficiency than the air compressor at all degrees of vacuum and
it is the best reciprocating pump that the writer has ever tested.
This pump was made for several years without water jacket
and no trouble was ever experienced with overheating. How-
ever, owing to the commercial air compressors being jacketed,
the makers using same made this a talking point and this com-
pany was obliged to jacket its pumps.
100
90
80
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Vacuum Ins. Mercury
PIG. 80. POWER CONSUMPTION AND EFFICIENCY OP MODIFIED
RECIPROCATING PUMP.
The Vacuum Cleaner Company used a Clayton pump on its
smaller plants which was fitted with a semi-rotary valve in each
end serving as an induction and eduction valve, while the heavy
poppet eduction valve of the air compressor was dispensed with.
The increase in efficiency that should have resulted from this
change was not realized. The reason for this can be more
readily seen by inspection of the indicator cards. Figs. 81
and 82.
Fig. 81 is a card taken from one of the Clayton compressors
fitted with combined induction and eduction valves, and Fig.
82 a card from a compressor with light steel induction and
eduction valves of the poppet type.
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146 VACUUM CLEANING SYSTEMS
It will be noted that the compresGdon line, a-d. Fig. 81, ex-
tends above the atmosphere line, the pressure at the time of
opening the eduction valve being 4 lbs. per square inch above
the atmosphere. This is due to tihe iailure of the meehanically-
opers^bed valve to open soon enough. This valve being also the
induction valve, it is necessary for the eduction port to be closed
before the induction port can be opened^ in order to prevent a
short circuit of air from the atmo^here into the separators.
This fact is responsible for the sudden increase in the pressure
at b, the eduction port having closed before the completion of
the stroke and the air in the clearance space being compressed
A-L6
Mm L-?rL5
V
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AIM.
V —
— ^a
Atm
PIGS. 81 AND 82. INDICATOR CARDS FOR CLAYTON AND MODIFIED
PUMPS.
to 6j/i lbs. above atmosphjere. The induction port is not opened
until after the beginning of the suction stroke resulting in the
high degree of vacuum at c.
Compare this with the card, Pig. 82. Here the compression
does not extend above the atmosphere line more than J4 1^*
per square inch and the eduction valve does not close until the
end of the stroke so that the vacuum at the beginning of the
suction stroke is no lower than during the entire stroke.
These pumps were working under the same conditions, i. e.,
15-in. vacuum in the separator. The M. E. P. for Fig. 81 is
7.05 while that in Fig. 82 is 6.7 and is higher than is usually
the case with this pump, due to the fact that the exhaust pipe
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VACUUM PRODUCERS 147
from this pump was very long and crooked, a condition which
should be avoided whenever possible. Also, the pump from
which this card was taken is one of the older pattern and the
clearance was greater than in the later models. The point at
which the eduction valve opens in Pig. 81 is 53% of the stroke
and it closes at 95% of the stroke and is, therefore, open 42%
of the stroke, while in Fig. 82 the eduction valve opena aA 46%
of the stroke and remains open to the end of the stroke, and^
therefore, is open for 54% of the stroke. Thus the pump with
the poppet valves will move more air at the same vacuum with
less expenditure of power than the pump with the mechanically-
operated valves.
Another type of reciprocating pump has been introduced in
the past two or three years in which a single valve which ro-
tates continuously in one direction is used for induction and
eduction valve, for both ends of the cylinder. This valve is a
plain cylindrical casting, having ports cored through to alter-
nately connect the cylinder ports with the intake and exhaust
ports.
By rotating this valve 180° on its stem the vacuum pump
is changed to an air compressor. This arrangement is adopted
in order to discharge the contents of the separator into the
sewer as was explained in Chapters I and VIII. In this pump
thef*e must be points at which both the induction and eduction
valves are closed at the same time and results similar to those
found with the semi-rotary valves of the Clayton pump will
naturally be in evidence. The author has endeavored to obtain
an indicator card from one of these pumps but has been un-
able to do so. The effect of simultaneous closing of both in-
duction and eduction ports would naturally be more marked in
this pump than in the Clayton, as the motion of the valve in
this case is uniform at all times while the motion of the valve
gear of the Clayton pump is so arranged that the valve moves
very fast at the time that both ports are closed. One of the two
pumps of this type which was recently installed in the New
York Post Office is illustrated in Fig. 83. These pumps have
a displacement of 1,200 cu. ft. each and are the largest recip-
rocating pumps in use for vacuum cleaning at this writing.
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148 VACUUM CLEANING SYSTEMS
An interesting property of the piston pump which lends
itself to the economical control of the vacuum in the system is
illustrated by the curve at the top of Fig. 78 which shows the
total power required to operate the Clayton type air com-
pressor, the efficiency of which is indicated by the lower curves
on this figure. The compressor was operated at constant speed
and the air volume varied to give various degrees of vacuum
from atmospheric pressure to a closed suction and the power
to operate the compressor read at intervals of two inches. The
current input to the motor in amperes is indicated by ordinates
and the vacuum in the separator by the abscissae. This indi-
cates that the piston pump requires the maximum power to
FIG. 83. ONE OF THE PUMPS INSTALLED IN CONNECTION WITH THE
VACUUM CLEANING SYSTEM IN THE NEW YORK POST OFFICE,
THE LARGEST RECIPROCATING PUMP USED FOR THIS
PURPOSE UP TO THE PRESENT.
operate at about 15-in. vacuum and that the least power is re-
quired when the vacuum is at the highest point possible to ob-
tain. The method employed in utilizing this characteristic of
a piston pump will be discussed in a later chapter.
Rotary Pumps. — The Garden City rotary pump is a good
example of the single-impeller type of pump and is or has
been used to some extent by at least two makers of vacuum
cleaning systems. Its interior arrangement is shown in Pig.
84. A solid cylindrical impeller, A, is mounted eccentrically in
the cylindrical outer casing, the impeller being fitted with four
sliding vanes which are provided with distance pieces, E, and
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VACUUM PRODUCERS 149
wearing faces, B. The oil reservoir is provided with a needle
valve which is automatically opened as soon as there is any
vacuum produced and closes automatically when the machine is
shut down. The rate of feed of oil is adjusted by the screw I.
This type of pump offers a large surface in rubbing contact
with the case and becomes very hot when in operation. It re-
quires liberal lubrication in order to prevent heating and cut-
ting of the surface of the casing. End wear in these pumps
causes leakage, and, as usually constructed, there are no means
FIG. 84. INTERIOR ARRANGEMENT OF THE GARDEN CITY ROTARY PUMP.
provided for taking up this wear. It can be provided for,
however, by using metal shins on the ends of the cylindrical
casing.
The power required to operaite this type of pump (Curve a-b,
Fig. 85), is nearly the same as that required to operate a piston
pump for vacuum less than 12 in. mercury, but when the vacuum
becomes higher, the power required becomes much greater than
that required by the piston pump. The efficiency (Curve o-e,
Fig. 85), is identical with that obtained with the light-weight
poppet valve pump (Curve c-e, Fig. 80) from to 11 in.
vacuum, but for higher vacuum the efficiency of this type of
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150
VACUUM CLEANING SYSTEMS
pump falls off, while the eflSciency of the pistx)n pump becomes
greater as the vacuum becomes higher. This difference in the
characteristics of the two types of pumps is due to the presence
of valves in one case and their absence in the other. With the
piston pump the atmospheric pressure reaches the cylinder
only while air is being discharged, the eduction valves being
closed at other times and a partial vacuum exists on both sides
of the piston. The higher the vacuum produced, the less time
there is atmospheric pressure on the piston until, when no air
MO
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PIG. 85. POWER REQUIRED TO OPERATE GARDEN CITY TYPE OP
ROTARY PUMP.
is discharged, the air contained in the clearance space of the
cylinder is compressed and expanded, the compression and
expansion lines being coincident. The indicator card will have
no area, and the only power expended is that required to over-
come the friction in the moving parts. With the rotary pump
there are no discharge valves to hold the atmospheric pressure
from the discharge side of the impeller and the compression of
the- rarified air is accomplished by the atmospheric pressure
admitting air through the eduction port into the chamber. As
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VACUUM PRODUCERS 151
it comes opposite the eduction port there is no difference in the
time during which the impeller is subject to atmospheric pres-
sure, no matter what the quantity of air being discharged. The
higher the vacuum in the
spaces' containing rarified air,
the greater the difference in
pressure on the opposite
sides of the sliding vane and,
therefore, the greater total
power required to turn the
rotor.
Another type of rotary
pump which is fast becoming
the most popular is the
double-impeller type. This is
generally known as the Root
blower, as the firm of this
name was the first to manu-
facture same. They have
been in use for many years
as blowers for gas works, and
as vacuum producers for
various purposes, mainly the
operation of pneumatic tube
systems.
Why this form of vacuum
producer was not earlier
adopted in vacuum cleaning
systems, instead of the slid-
ing-vane type, is hard to
understand. This pump con-
tains two impellers or cams
which are mounted on ^shafts
FIG. 86. ARRANGEMENT OP glared together and revolve
R8??k?-^^P^u^M''^^^o^^%Ac'iF^S in opposite directions inside
CLEANING WORK. ^f ^ ^^^ ^j^^y^ j^.^^ .^
close proximity to the case and to each other, but never touching.
They are, therefore, frictionleas in operation and the introduc-
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152 VACUUM CLEANING SYSTEMS
tion of a small amount of water renders them practically air
tight. There being no metallic contact between the moving
parts, internal lubrication is unnecessary and there is no wear
on either the impellers or the casing and no means of taking
up wear are necessary.
The arrangement of the impellers and the method of provid-
ing water to seal the parts is shown in Fig. 86. A reservoir
containing water is provided on the discharge side of the pump
and a small pipe leads from this reservoir to the suction side of
the pump. The vacuum lifts water from the reservoir and dis-
charges same in a spray into the suction chamber. This water
passes through the pump and is separated from the air in the
discharge chamber to be returned to the suction chamber by the
PIG. 87. ROTARY PUMP ARRANGED WITH DOUBLE-THROW SWITCH
FOR REVERSING PUMP.
vacuum. This operation will start automatically as soon as any
degree of vacuimi is formed and will cease as soon as the pump
is shut down.
Any of these rotary pumps having no valves can be changed
to an air compressor by reversing the direction of rotation.
This is adapted by the American Rotary Valve Company in
connection with their wet separators to discharge the contents
of the separator into the sewer, on all of their smaller-sized
plants. Fig. 87 shows one of these plants arranged with double-
throw switch for reversing the electric motor used to operate
the pump and also shows the arrangement of the rotary brush
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VACUUM PRODUCERS
153
which is used to clean the screen in the wet separator, as has
been explained in Chapter VIII.
The power consumption and efficiency of this type of pump
are shown in Fig. 88. The watts per cubic foot of. free air
mo
150
120
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40
30
20
10
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Vacuum Ins Mercury
FIG. 88. POWER CONSUMPTION AND BPPICIBNCY ROOT TYPE OP PUMP.
(Curve a-b) show a much lower consumption of power at the
lower vacuum than any of the pumps already tested. This is
probably due to the fact there is no internal friction. It will
PIG. 89. THE ROTRBX VACUUM PUMP, USED BY THE VACUUM
ENGINEERING COMPANY.
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154 VACUUM CLEANING SYSTEMS
be noted that the power to operate at no vacuum is but 10
watts per cubic foot of free air, while all the others require
from 24 to 34 cubic feet. This also results in the eflSciency
curve (c-e, Fig. 88) reaching its maximum value at a lower
vacuum than in the case of the sliding vane pump (Fig. 85).
The eflSciency is fairly constant between 6-in. and 10-in.
PIG. 90. LATE TYPE OP CENTRIFUGAL EXHAUSTER MADE BY THE
SPENCER TURBINE CLEANER COMPANY.
vacuum and is much higher than is obtained with any of the
other types of pumps at these vacua. When they are operated
at higher vacuum the eflSciency is about the same as obtained
with the sliding vane pumps and lower than that obtained with
the reciprocating pumps. The best eflSciency of this pump is
at the vacuum necessary to operate a cleaning system provided
with lj4-iii. hose.
A slight modification of this type of pump is that used by the
Vacuum Engineering Company, known as the Rotrex. This
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VACUUM PRODUCERS
155
pump has but one impeller, of nearly the same form as the
imi)ellers in the Root blowers and has a follower, driven by
crank and connecting rods which is always in close proximity
to the impeller but does not touch same. The arrangement of
K) 100
9 90
7:|70
5| 50
4^40
5 I 30
1
,
2
s
4.
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PIG. 91.
POWER AND EFFICIENCY CURVES FOR THE SPENCER
MACHINE.
this pump is illustrated in Fig. 89 w*hich also shows the satura-
tion chamber and screens used instead of a separator, as ex-
plained in Chapter VIII.
The author thas never tested the economy of these pumps but
would infer that their economy should be about the same as
that of the Root blower.
Centrifugal Exhausters. — This type of exhauster has always
taken the form of a fan. The first stationary fan type of ex-
hauster was manufactured by the Spencer Turbine Cleaner
Company. Their latest type is illustrated in Fig. 90. It con-
sists of a series of centrifugal fans mounted on a vertical shaft,
stationary deflection blades being provided between the wheels
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156
.VACUUM CLEANING SYSTEMS
to conduct the air from the periphery of one wheel to the
center of the next.
These centrifugal exhausters do not have a positive displace-
ment, as do all those already described, and therefore the varia-
tion of the vacuum is not as much as in case of the positive
displacement madhines. The vacuum produced when the ma-
chine is moving no air is slightly less than the maximum that
PIG. 92. INTERIOR ARRANGEMENT OP INVINCIBLE MACHINE, MANU-
FACTURED BY THE ELECTRIC RENOVATOR MANU-
FACTURING COMPANY.
the exhauster can produce and there is very little variation in
the vacuum with air quanltities which can be moved without
exceeding the capacity of the motor or other means producing
the power. The curves showing the power required to operate
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VACUUM PRODUCERS
157
and the efficiency of this type of vacuum producer are, there-
fore, plotted with abscissae representing the iair moved in
cubic feet per minute. The vacuum produced and the power
required to operate are plotted as ordinates. The curves for
the Spencer machine are shown in Fig. 91. This curve is taken
from a flour-sweeper machine and the vertical lines numbered
4 140}
5'§30
Z 20
I
K)
^^z
055
100 zoo 300 400 500
CaFt AtmosAir perMinu-t©
FIG. 93.
POWER CONSUMPTION. VACXJUM AND EFFICIENCY OF FIRST
TYPES OF INVINCIBLE MACHINE.
1 to 4 represent the conditions when that number of sweepers
Sive in operation; that is, bare floor renovators, with 50 ft.
of hose or 80 cu. ft. of free air per minute. The maximum
-efficiency is reached at full load and is approximately 42%.
The vacuum at this efficiency is 5J4 in. mercury, a drop of ^-in.
from the maximum which was obtained at one-fourth load.
These machines have rather large clearances and a prelimi-
nary separator is all that is required. They operate at a speed
of about 3,600 R. P. M. and the peripheral speed of the fans
varies from 15,000 to 22,000 ft. per minute. This produces
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158
VACUUM CLEANING SYSTEMS
some noise and considerable vibration and care must be exer-
cised in mounting tbe machine. In order to insure quiet run-
ning the usual method is to place the machine on a felt pad
of considerable thickness.
The machines made by the Electric Renovator Manufactur-
ing Company are horizontal and have much smaller clearances
than the Spencer machines. They operate at approximately
the same rotary and peripheral speed and are, therefore, as
11 110
K) 100
200 300 400
Cu FtAtmos.Air per Mfnu+e
500
FIG. 94.
POWER CONSUMPTION, VACUUM AND EFFICIENCY OF IN-
VINCIBLE MACHINE AFTER VALVE WAS FITTED
TO DISCHARGE.
noisy. However, the center of gravity of these machines is
lower and the vibration is not so great. The Spencer Company
is now making a horizontal machine which it furnishes only
when required, the claim for their vertical machine being that
the weight of the moving parts counteracts the thrust of the
atmospheric pressure against the fans and relieves the work of
the thrust bearings, at the expense of greater vibration. With
ball bearing thrusts, the author does not consider this to be of
great importance.
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VACUUM PRODUCERS. 159
A view of the interior arrangement of the Invincible machine,
as manufactured by the Electric Renovator Manufacturing
Company, is shown in Fig. 92.
These machines, when first made, were without valves and
the power consumption, vacuum and efficiency are shown in
Fig. 93. It will be noted that the vacuum produced, when the
machine is operated at or below one-half load, is considerably
lower than is obtained at greater loads. This characteristic
PIG. 95. F(5tJR-SWEEPER INVINCIBLE PLANT INSTALLED IN THE
UNITED STATES POST-OFFICE AT LOS ANGELES, CAL.
produces a disagreeable noise when the machine is not handling
any air, evidently due to air rushing back through the outlet
when the vacuum tends to build up to the maximum which
occurs at intervals of about one-hialf second.
In order to overcome this trouble a valve has been fitted to
the discharge, as indicated at 4, Fig. 92. With this valve in
place the power consumption, efficiency and vacuum are as
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160 VACUUM CLEANING SYSTEMS
ebown in Fig. 94. It will be noted that the vacuum is as high
at no load as at any load up to full load and is practically
constant. The efficiency at light loads is the same as before but
it is slightly lower at full load, being 50% without the mlve
and 47% with the valve. This is due to the power being ex-
pended in opening the valve for large quantities of air and to
friction in the valve passage.
A fournsweeper plant of this manufacture is shown in Fig.
95. This plant is installed in the United States Post Office
at -Los Angeles, Cal. The separate centrifugal separator,
shown at the left of the cut, is not used in Uie regular equip-
ment and was added in this case to fullfil the specification re-
quirements.
A centrifugal pump with a single impeller is manufactured
by The United Electric Company and is known as the Tuec
system. A phantom view of the pump and separator is shown
in Fig. 96. It will be noted that the shaft is vertical. How-
ever, the vacuum is under the impeller in this case, and the
thrust due to the atmospheric pressure is down instead of up,
as in the case of the Spencer machines. This throws the weight
of the parts, plus the thrust due to atmospheric pressure, on
the thrust bearing. These machines do not produce a vacuum
greater than 3-in. mercury, and the additional thrust is not as
great as in the ease of the machines producing higher vacuum,
the impeller being 24 in. in diameter, its area 450 sq. in. and
the thrust, with a vacuum of 3-in. mercury, 675 lbs., which
is worth considering. This downward thrust is partially ooun-
terbalanced by mounting the armature of the electric motor
used to operate the fan, slightly below the magnetic center,
thereby causing an upward magnetic pull. These machines are
intended to be used with large hose and pipe lines to reduce
the friction to a very low point. "When operating carpet reno-
vators the vacuum at the renovator rises to 1^-in. mercury and
the type of renovator used by them passes approximately 50
cu. ft. of air, while the bare floor renovators pass approximately
95 cu. ft. They are extensively used where bare floor work
is required, their first cost being low.
The results of tests of two of these machines of four-sweeper
capacity, driven by alternating and direct-current motors,
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VACUrai PRODUCERS 161
respectively, are shown in Fig. 96a. These curves indicate a
considerably higher efficiency with the alternating than with
the direct-current motor. This is due to the low efficiency of
the special high-speed direct-current motors used with all centri-
PIG. 96. CENTRIFUGAL PUMP WITH SINGLE IMPELLER, MANU-
FACTURED BY THE UNITED ELECTRIC COMPANY.
fugal fan-type exhausters. The alternating-current motors are
not so affected, in fact, the speed at which these fans are
operated is fixed by the requirements of the alternating-current
motors.
The efficiency of the other types of centrifugal exhausters
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162
VACUUM CLEANING SYSTEMS
(Figs. 91, 93 and 94) is in every case accomplished with direct-
current motors. This machine has an efficiency about the same
as the Spencer machine. It will noted that the vacuum produced
does not fall off as the load increases, as in the case of the multi-
stage fans. This characteristic is probably due to the fact that
there is no wire drawing in the diversion vanes, as in the case of
the multi-stage exhauster.
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FIG. 96a.
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free Air per Minute. Cubic Feet
TEST OF CENTRIFUGAL. PUMP WITH SINGLE IMPELLER
600
Steam Aspirators.— The steam aspirator as a vacuum pro-
ducer in connection with vacuum cleaning systems was first used
by the American Air Cleaning Company, and has been used
to a limited extent by the Sanitary Devices Manufacturing Com-
pany. The type of apparatus used by the American Air Cleaning
Company is illustrated in Fig. 97. A single partial separator is
used with this system and the lighter dust is allowed to pass
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VACUUM PRODUCERS 163
through the aspirator, where it is mixed with the steam and
sterilized. The aspirator is in the form of an ejector, with a
specially designed nozzle, and is always fitted with an automatic
device for cutting oflf the steam when the vacuum in the sepa-
rator reaches the degree desired.
The steam consumption required to exhauat 1 cu. ft. of
free air at various vacua, as determined by actual test of four
different nozzles, is shown in Fig. 98, the steam being the actual
weight of dry and saturated steam at the gauge pressures noted.
'fo5tacf<
PIG. 97. STEAM ASPIRATOR USED BY THE AMERICAN AIR CLEAN-*
ING COMPANY.
The American Air Cleaning Company used to guarantee a
steam consumption of 250 lbs. per hour from and at 212** 'F.,
assuming that the feed water temperature was 32° F., the
vacuum to be maintained at 9 in. mercury at the aspirator.
Taking the results of the test of the three-sweeper nozzle as
an average, 0.066 lbs. of steam will be required to exhaust 1
cu. ft. of free air at 9 in. vacuum. The total heat in 1 pound
of dry steam at 110 lbs. gauge is 1187 B. T. U. and at
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164
VACUUM CLEANING SYSTEMS
212° P. the latent heat is 970 B. T. U. The factor of
evaporation, therefore, is 1.235, and the weight of steam at 110
lbs. allowed by the guarantee i^ 202 lbs. This amount of steam
will exhaust 3,060 cu. ft. per hour, or 51 cu. ft. per minute,
which is more than sufficient to operate a carpet renovator, and
is a little less than will pass through a bare floor brush attached
to the end of 50 ft. of 1 in. diameter hose, if the hose is
attached directly to the aspirator. With a line of pipe between
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Vacuum Ins Mercury
FIG. 98. STEAM CONSUMPTION OP STEAM ASPIRATOR.
the hose cock and the aspirator, the air quantity will be some-
what less, and this guarantee will undoubtedly be fulfilled in
ev^ry case.
The advisability of using an aspirator will depend on th«?
conditions to be met at the building in each case. Three typical
cases are cited below:
I. When there is a Generating Plant in the Building, and
a Plant Using ij^-in. Hose and 8-in. Vacuum is Desired.—
A Root blower will require 27 watts for each cubic foot of air
exhausted (Fig. 88), and the three-sweeper aspirator, 0.065
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VACUUM PRODUCERS 165
lbs. of steam. Then the pounds of steam required by the
aspirator to do the same work as one K. W. hour at the motor
of the Root blower will be
0065X60 _ g
0.027 ^ '^
The generating plant will produce a kilowatt hour at the switch-
board with not exceeding 60 lbs. of steam, and if the trans-
mission loss is 10% there will be required by the Root blower
not over 66 lbs. of steam ix) do the same work that takes 146
lbs. with the aspirator. This case would require that the Root
blower, driven by an electric motor, be used.
2. When there is High Pressure Steam Available, but no
Generating Plant. — Then we may use either the aspirator or
a Root blower driven by a steam engine. This engine should
have an economy of 60 lbs. per indicated horse power, with not
over 15% friction loss, which will require 69 lbs. per brake
horse power. This will be equivalent to 69X0.776=90>$ lbs.
per K. W. hour, which is still much better than 146 lbs. required
by the aspirator.
3. When Steam is Generated on the Premises with Coal
Costing $3.00 per ton and all Machinery Must be Driven by
Electricity Purchased for 5 Cents per K. W. Hour. — Cost of
lyteam to do the same work in the aspirator that 1 K. W. hour
will do in a motor driving a Root blower is :
7X2240
as against 5 cents that would have to be paid for current. In
this case there would be a saving in using the aspirator, which
would not require as much attention as the motor, and at loads
less than full load, the steam used by the aspirator would be
in direct proportion to the load, as the control would shut the
steam off entirely during a portion of the time, while the motor
would require some current as long as it was in operation, even
if no air was being exhausted. On the other hand, the steam
which is exhausted from the aspirator is not suitable for use
in heating, as it is mixed with air and fine dirt, and must be
thrown away, a condition that must always be considered where
there is an opportunity to use exhaust steam for heating or
other purposes.
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CHAPTER X.
Control.
When the displacement type of vaeuum producer of more
than one-sweeper capacity is used with ta vacuum cleaning
system, some means must be employed to prevent the vacuum
rising above that necessary for efficient operation of the sweepers
wben there are less renovators in use than the capacity of the
vacuum producer or when carpet renovators are in use on all
outlets.
If the displacement pump be run at constant speed, every
change in the quantity of air exhausted will cause a change
in the vacuum p«)duced. This will result in inefficient opera-
tion and may result in undue effort being necessary to operate
the renovator and in excessive wear on the carpets.
The earlier systems were not provided with any control and
the first attempt to control the vacuum was by placing a spring
relief valve on the pipe line near the separator, which admitted
additional air when the vacuum tended to rise. This resulted
in full load being thrown on the pump at all times when the
same was in use, which does not give economical operation.
The controllers that have been devised for maintaining a
constant vacuuul without the introduction of air into the
system operate on one of three principles :
1. Closing the suction of the vacuum producer.
2. Opening the suction of the vacuum producer and holding
vacuum in the efystem.
3. Vaiying the speed of the vacuum producer.
The first type of controller was introduced in the vacuum
cleaning field by the Sanitary Devices Manufacturing Company^
and was known as the "unloading valve.'' It was similar to
the unloader which had been used for some time in connection
with air compressors. The detail of construction is shown in
Fig. 99, and consists of a balanced valve, which is con-
166
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CONTROL 167
neoted tx) a weighted piston, operating in a ohamber com-
municating with the separators by a pilot valve. The pilot
valve is operated by an auxiliary piston which is weighted
to overcome the lifting effort due to the vacuum desired.
When the vacuum in the cylinder
becomes great enough to overcome
the weights attached to the aux-
iliary piston, it rises, allowing
vacuum to reach the main piston,
which is drawn up and the suc-
tion valve closed. When this valve
is closed the vacuum in the pump
at once starts to build up to the
maximum possible for the pump
to produce, and if the pump used
is of the piston type the vacuum
will run up to nearly 28 in., re-
sulting in the pump's taking the
least power on which it can be
operated. As soon as the vacuum
in the separators falls below that
which will sustain the weight on
the auxiliary piston the valve falls
open and the pump again draws
air through the system. In actual
practice this valve will operate at
more or less frequent intervals.
The author timed the action of
one of these valves connected to
PIG. 99. FIRST TYPE OF CON- ^^e suctiou of au eight-sweepcr
TROLLER INTRODUCED BY THE . v v/x oox cagxiu-ow^pcx
SANITARY DEVICES manufxc- pistou pump, and its time varied
TURING COMPANY, KNOWN AS f 2/5 SeCOUd tO 65 SCCOUds.
THE "UNLOADING VALVE." ' ^ uv v/t/ ocv.vxxv«.
The current taken by the pump
when the suction was open was 100 amperes at 220 volts. When
the valve was closed for but 2/5 second the current dropped to
75 amperes, there not being sttfficient elapsed time for the pump
to produce a perfect vacuum. When the valve was closed for
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.168
VACUUM CLEANING SYSTEMS
2 1/5 seconds, the vacuum reached its maximum value and the
current fell to 32 amperes.
Pig. 100 is a curve plotted from the results of this test
and shows an increase in the power above that necessary to
overcome the friction in the moving parts of the pump in
direct proportion to the percentage of full load that the pump
was serving.
This is as near an ideal condition as one could expect to
obtain by any means other than stopping the pump or other-
wise decreasing the friction load. However, this form of
^ 5 4 5 ^
Sweepers in Use
FIG. 100. TEST OF CONTROLLER CONNECTED TO SUCTION OP
8-SWEEPER PISTON PUMP.
unloader is not suitable for a pump without valves, as the
power will increase with an increase in vacuum, and other
means must be employed to control such a pump.
The second form of control is adapted to this type of pump.
The arrangement of one of these controls is shown in Fig. 101.
This consists of a single-ported vaJve opened by the vacuum
in the cylinder, M, the action of which is controlled by a pilot
or auxiliary control valve actuated by the vacuum in the sep-
arator. This auxiliary valve is fitted with two pistons, S and
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CONTROL
169
O, which are held together by springs, and when so held the
main cylinder is open to the atmosphere through the small
ports in the piston, O. When the vacuum in the separator
becomes great enough to overcome the compressive strength of
the springs, T and P, the pistons, S and 0, are drawn apart,
closing th-e port in the piston, 0, and opening the port in piston,
S, allowing the vacuum to enter the main cylinder, M, and
open the main valve. This valve permits the atmospheric
preesure to enter the pump suction, the air being prevented
from entering the separators by a check valve, not shown. The
pump then operates without producing any vacuum, and the
R*li9\
FIG. 101.
TYPE OF CONTROLLER FOR USE ON PUMPS WITHOUT
VALVES.
power required to operate the pump is reduced. A relief valve
of the common vacuum-breaker type is shown at the left of
the cut. This valve is provided to prevent overload in case the
control fails to operate.
This type of control does not effect as great a reduction in
the power as the first type of control described, since it requires
a greater per cent, of the full load power to operate the pump
at no vacuum than at perfect vacuum. No air is moved in the
latter case, and the maximum volume of air is moved in the
former case.
Either of these controls gives fairly economical results when
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170 VACUUM CLEANING SYSTEMS
the pump is serving at least a part of the sweepers at all times.
However, when the system is used in a building where there
may be cleaning done at any time and vacuum must be '*on
tap ' ' at all times, as in a hotel, there will be many occasions when
no sweepers will be in use, and the pump might then be stopped
entirely, provided that it could be automatically started when
needed.
FIG. 102. REGULATOR FOR MOTOR-DRIVEN VACUUM PUMP, MANU-
FACTURED BY THE CUTLER-HAMMER MANUFACTURING CO.
Where the steam aspirator is used, the control (Fig. 107) is
attached to the steaan supply valve. When the valve is closed
no steam is consumed by the aspirator. This is the ideal con-
dition where we must keep vacuum *'on tap," and is a char-
acteristic of the aspirator system which has led to its intro-
duction in many instances.
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CONTROL 171
The same economy can be obtained with a steam-driven
pump by inserting a throttle valve, controlled by the vacuum
in the separators, which will start and stop the engine driving
the pump and vary its speed in accordance with the quantity
of air required by the systeni.
Several appliances for varying the speed of a motor-driven
vacuum pump have been placed on the market, the simplest
and probably the best of these appliances being that manu-
factured by the Cutler Hammer Manufacturing Company, illus-
trated in Figs. 102 and 103.
The object of the apparatus shown in Fig. 102 is to auto-
matically start a motor-driven vacuum pump and control the
PIG. 103. INSPIRATOR TYPE VACUUM CONTACTOR, USED TO CONTROL
PILOT MOTOR OP CUTLER -HAMMER CONTROLLER.
speed of the motor so that the vacuum is maintained at the
desired degree, irrespective of variation in the number of
sweepers in use. This control of the degree of variation is
accomplished in a more efficient manner than if the pump were
to be driven at its maximum speed at all times and the pressure
kept at the desired point by means of a blow-oflf or by-pass
valve. With this system a motor is used having a control, by
shunt field weakening, of approximately 3:1 in order that the
control of the speed may be as efficient as possible.
Referring to Fig. 103, a small pilot motor is mounted
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172 VACUUM CLEANING SYSTEMS
on brackets at th-e side of the panel, driving directly, through
an insulating coupling, a screw shaft which carries a traveling
cross-head. This cross-head is shown in the photograph at the
extreme right of its travel, which corresponds to the maximum
speed of the motor, the left-hand end corresponding to zero
speed of the motor. In this position the motor circuit is opened
by the clapper type magnetic switch. Assuming that the cross-
head is in the extreme left-hand position and the knife switch
is closed, the pilot motor will be started in such a direction as
to move the cross-head to the right A slight movement in this
direction completes a connection to the magnetic switch, which
thereupon closes the motor circuit through all of the resistance,
starting the pump motor.
Inasmuch as the pilot continues to move the cross-head
toward the right, the speed of the pump will be gradually
increased until, at a point about midway of its travel, all of
the resistance in the armature circuit of the motor will have
been cut out upon the upper segments and further movement
then serves to weaken the field. This is aeeomplishd by means
of the contact buttons shown just below the screw shaft.
As soon as the cross-head has weakened the field to its mini-
mum value and thus speeded the motor up to its maximum
point, a limit switch stops the pilot motor and thus prevents
further motion in that direction. As soon as the pump working
this at its maximum speed has produced a vacuum in the
cleaning system of, say, 12 in. of mercury, the cross-head will
begin to move backward and reduce the speed to a point cor-
responding with the air required.
This control of the pilot motor is accomplished by means of
what is termed ''inspirator type vacuum contactor.*' This
apparatus is shown more in detail in Fig. 103, and consists of
a diaphgram closing one side of a chamber. The diaphragm
is pressed outward by an internal spring whose tension may
be adjusted by means of a hexagonal head cap screw, visible
in the photograph of the complete regulator.
The diaphragm is coupled to a pivoted arm carrying insu-
lated conical-pointed silver screws, so located that they enter
holes in small silver plates mounted on opposite sides, respec-
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CONTROL 173
tively, of the upper and lower contact posts. These contact
posts are hollow and communicate with the diaphragm chamber,
which latter is connected by piping to the vacuum system.
Normally, the internal spring forces the diaphragm over so
that the lever makes contact with the lower post. This serves
to drive the pilot motor in a direction to move the cross-head
to increase the speed of the pump. Wlien the degree of vacuum
for whidh the apparatus is adjusted is reached the lever starts
to move itoward the left hand, and in so doing stops the pilot
motor. This maintains the pump speed at that particular value.
Should the vacuum increase to a sufficient degree the lever
will be drawn further over toward the left and contact will
then be established with the upper post, whidh will oause the
pilot motor to move the cross-head to the left, and thus decrease
the pump motor speed.
Inasmuch as the motion of the diaphragm lever is very grad-
ual, destructive arcing would take place at the pilot motor con-
tacts were it not for the small openings in the silver contact
plates, which, as the pointed screw leaves the hole, immediately
sucks the are inward and extinguishes it.
This method of preventing arcing is exceedingly unique and
is subject to patents now pending.
It is possible to adjust the high and low limits by changing
the setting of the pointed silver screws, the usual adjustments
being such as to maintain the vacuum within 2 in. of mercury.
The speed of the pilot motor may be adjusted by means of
the small link shown in the upper left-hand comer of the panels
to correspond with the capacity of the system, it being found
that systems of large eapacity require a slower motion than
those in which the amount of piping, etc., is less for the same
size of pump. In practice, the regulator will very quickly find
the position corresponding to the proper speed for the number
of outlets in use, and only moves a slight amount either side
of this particular position.
With this regulator it is possible to employ remote control
permitting the establis;hment of vacuum in the piping system
by the turning of a pilot switch located at any point in the
building. If desired, several such switches may be placed in
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174 VACUUM CLEANING SYSTEMS
parallel, and, under these conditions, the turning on of any
switch will establish the vacuum supply which will be main-
tained until all of the pilot switches are turned oflf. By this
means it is possible to have several janitors working at the
same time on different floors of the building, and each will be
independent of the others in his control of the vacuum; al-
though one man may finish and turn off the switch on his floor,
the pump will not be stopped if the vacuum is still required by
workers on other floors.
When the total size of one installation becomes greater than
25 H. P., it is found desirable to provide two pumping units,
and, in this case, the same system is applicable. The cross-
head is then arranged to start first one pump and increase its
speed to a maximum. If this does not supply the necessary
amount of air, the cross-head continues to move, and starts the
second pump, whicii will then be run at a necessary speed to
supply the remaining amount of air.
The first pump always remains in motion at its point of
highest efficiency. It is evident that this duplex arrangement
is more efficient than one large pump when only a very few
sweepers are in operation, since,, for this condition, the very
large pump would have to be run at such a slow speed that the
armature resistance would be in circuit, while the single smaller
pump would be running at a more efficient speed and with les»
proportionate motor losses.
In duplex outfits switches are provided for disconnecting
either motor in case of its being necessary to clean or repair
either unit. When so disconnected the other unit may be oper-
ated and maintain the same degree of vacuum within the limits
of its capacity.
While this type of control is more economical in current con-
sumption than either of the former types described, its cost is
much higher, and it is seldom used unless specifically ordered.
When the centrifugal type of vacuum producers is used no
control is necessary, as the inherent feature of this type of
apparatus insures a practically constant vacuum at all air quan-
tities within the capacity of the machine.
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CHAPTER XI.
Scrubbing Systems.
Vacuum cleaning systems in which appliances for scrubbing
;are provided in addition to the usual appliances for the removal
of the duat and oth-er materials in a dry state have been intro-
duced by a few manufacturers, none of which has come into
:general use.
The usual method employed is to provide an ordinary corn
:Scrubbing brush which has a connection to the water supply of
the building, with control valves in the tool handle for regu-
lating the flow of water to the brush. Soap is applied either in
the form of soap powder sprinkled on the floor, in a liquid
tstate fed into the water supply by means of a sight-feed oil cup
.or soft soap in a plastic state fed into the water supply by means
x)f a compression grease cup.
In any case, the water is run onto the floor mixed with the
;Soap and the floor scrubbed by manipulating the com brush,
in the same manner that an ordinary com scrubbing brush
-without attachments would be used.
After the dirt has been loosened from the floor, the floor may
be rinsed by the application of more water. The water is then
drawn up from the floor by the suction of the cleaning machine,
.and passes through the hose and piping system to the separator
and vacuum producer. To effectively remove the water a rub-
ber-faced tool is usually employed. In one system this rubber
face is arranged to permit the com brush to be fitted over same
when scrubbing is being done, and the brush must be removed
from the tool before the water can be drawn up from the floor.
Other manufacturers provide a double-faced tool having the
brush on the opposite side of the tool from the rubber-faced
:slot. By reversing the tool, scrubbing and mopping can be
.accomplished without the removal of the com brush from the
;tool, which is more convenient for the operator.
175
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176 VACUUM CLEANING SYSTEMS '
With either of the above forms of scrubbing tools it is neces-
sary or desirable to cut off the suction to the mopping attach-
ment when using the com brush, and it is also necessary to
cut off the water supply to the brush when using the mopping
attachment. One system, introduced several years ago, con-
ducted the water to the brush and away from the rubber-faced
mopping appliance through the same hose. This arrangement
requires the use of a special three-way hose cock, which had to
be manipulated frequently during the scrubbing operation,
requiring the time of another person in addition to the operator,
or else greatly delaying the scrubbing process 'by requiring the
operator to constantly pass back and forth beftween the hose
cock and the scrubbing tool. This method of supplying water
also requires the use of a removable com brush attached over
the rubber mopping device.
Other forms of scrubbing appliances are provided with sep-
arate hose for the water supply and suction and with valves
in the handles for controlling the suction and water supply.
These valves to be efficient and quick in action are generally
made self-closing, otherwise they will be short-lived, as
explained in Chapter V. When springs are used to close the
valves, the hand and wrist will be quickly fatigued, as stated
in Chapter V.
With either of the above systems all of the scrubbing, that
is, the agitation of the brush, has to be performed by the oper-
ator, as in the case of the ordinary scrubbing brush. However,
the combination tool is much heavier and clumsier than the
ordinary scrubbing brush, and the only advantage obtained by
using this heavy and clumsy appliance is the ability to supply
water without carrying it in buckets, also the removal of the
dirty water after scrubbing. These appliances cannot be termed
mechanical scrubbers, nor can they be classed with scrubbing
machines with motor-driven brushes, such as have been recently
introduced.
A real mechanical scrubbing device for use with a vacuum
cleaning system was manufactured by Foster & Glidden, of Buf-
falo, N. Y., but was never placed on the market, although at
least one is in commercial operation to-day. This machine is
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SCRUBBING SYSTEMS 177
provided with a turbine motor operated by the air current
passing through the machine. This turbine revolves a pair of
scrubbing brushes turning in opposite directions. Water is fed
through a separate hose, and an auxiliary air inlet is opened
when the suction under the brushtes is closed, in order to supply
the necessary air to keep the turbine running. Mr. Foster
states that he has experienced no trouble in operating this
machine on from 8 in. to 12 in. of vacuum, being able to scrub
and remove the dirt and water with one operation. The speed
with which the work was done depended on the condition of the
floor, the usual rate, as given by Mr. Poster, being from 10 to
12 yds. per minute.
Mr. Foster also states that he has not pushed the introduction
of this scrubber, as he considers it so far ahead of the times as
to require the education of the public in the use of the hose
and ordinary vacuum cleaning tools before users would be
capable of successfully operating this, type of scrubber.
The author considers this condition to be lamentable if true,
for until some such appliance is in commercial use scrubbing
attachments to a vacuum cleaning system can never compete
with the mechanical scrubbing machines now on the market,
and are little if any better than the old method of scrub-
brush, mop and pail, and certainly not as rapid in operation.
When the vacuum cleaning systems combine scrubbing witli
dry cleaning, the separator and vacuum producer must pro-
vide for the removal of water as well as air. A few manufac-
turers have attempted this, among which are the makers of the
Rotrex system, described in Chapter IX, in which the water
is passed through the pump and into the sewer under sufficient
pressilre to overcome the friction in the exhaust pipe through
which the expelled air passes after leaving the separator. This
may be sufficient to force the trap seals of the plumbing system,
and, if used, the discharge connection should be made to the
sewer outside the main running trap, close to the fresh air
inlet. As large articles cannot be allowed to pass through the
pump, a screen is necessary on the inlet side of the vacuum
producer, but this may give trouble, due to the clogging with
litter.
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178 VACUUM CLEANING SYSTEMS
The Atwood Vacuum Cleaner Company uses a wet tank on
the suction side of the vacuum producer into which the dirt
and water are discharged, the air being separated and passed to
the vacuum producer. When this tank becomes partly filled
it is necessary to shut down the plamt and empty the contents
of the tank by gravity into the sewer.
This method overcomes the objections to clogged screens and
forced trap seals, and all litter is discharged direct to the sewer,
together with a quantity of water which is presumably sufficient
to flush the litter through the sewer. The last named system is
still open to two objections; first, it is not automatic, and, if
neglected, the tank wiU fill with water and force same into the
vacuum producer. With the Root type of vacuum pump this
will do little harm unless a large quantity of floating litter
rfiould pass into the pump. Second, the system may De oper-
ated with dry renovators exclusively for a considerable portion
of the time, in which case the contents of the 8ei)arator may
become of such a consistency as will not readily flush through
the sewer, and stoppage of the same may occur.
Another separator of this type has recently been paitented by
E. B. Dunn, the originator of the Dunn Locke, in which the
mud and the water are automatically discharged alternately
from one of two separators, as described in Chapter VIII.
Such a separator, in which sufficient water is automatically
introduced to dilute the dirt and which will automatically
empty when sufficiently filled, when so constructed that it will
operate continuously, is considered to be the ideal separator for
use with a combined cleaning and scrubbing system. Until the
mechanical scrubber and an automatically operated separator
are commercially introduced the author does not consider that
the use of scrubbing attachments, in connection with the vacuum
cleaning system, is advisable.
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CHAPTER XII.
Selection op Cleaning Plant.
We have oansidered in detail the various appliances which,
taken together, make a complete vacuum cleaning system, but
without considering their relation to one another. It now be-
comes necessary to choose <an exact type and form of each of
these appliances which will produce in combination a com-
plete vacuum cleaning system beat suited to the conditions to
be met in a given installation.
In selecting a vacuum cleaning system consideration must be
given to the character of the material to be removed, the kind
and quality of the surfaces to be cleaned, the rate at which
cleaning must be done, the extent of the cleaning system, and
the cost of labor to operate the system, all of which must be
considered in each step in the selection of a suitable plant.
In assembling the complete system, the author will take up
the various parts thereof in the order in which they were dis-
cussed in the preceding chapters.
Renovators. — The selection of renovators is the most impor-
tant step in making up a vacuum cleaning system, as the entire
makeup of the system, whether good or bad, is dependent on
the proper selection of these tools. The carpet renovator is
generally considered first in importance, because the cleaning
of carpets has nearly always been found to be the principal field
of usefulness in vacuum cleaning work. This is due, perhaps,
largely to the fact that from the beginning of the art of vacuum
cleaning, this function of the system has been held before the
eyes of the public by the manufacturers of the earlier systems.
Nearly all demonstrations of cleaning systems shown to the
public consist of the removal of ordinary wheat flour from a
carpet. The reason for this is two-fold; first, because it is
the most striking demonstration to the eye of the layman, and,
second, it is the easiest to accomplish with a small air displace-
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180 VACUUM CLEANING SYSTEMS
ment and small power, which was characteristic of the apparatus
made by these manufacturers.
The author was at one time of the opinion that this function
of the cleaning plant was given too much pronuinence by-
builders of systems having small air displacement, and letters
were sent to the officials in charge of sixteen Government
buildings in which vacuum cleaning systems were installed,
asking them, among other questions, w^hether the cleaning sys-
tem was used to any extent in cleaning bare floors, of which
there were large areas, both wood and marble, in the buildings
in question. The plants installed were of various makes, some
of which maintained 12 in. mercury at the separator and used
1-in. hose, while about an equal number of others maintained
6 in. mercury at the separator and used lj4-in. hose. The
answers showed that out of the sixteen buildings the cleaner
was used on bare floors in but two of the buildings. One
writer, who had a plant mainitaining 6-in. vacuum, provided
with Type F renovators and lj4-in. hose, stated that he had
tried cleaning bare floors without success, as the renovator and
hose became so clogged with litter as to be inoperative. The
majority stated that the cleaning system displaced brooms on
carpets and rugs and several stated that the cleaning system
was used to advantage in cleaning walls, cases, pigeon holes
and relief work.
This indicates that for the average office 'and departmental
building the cleaning of oarpets is the most important function
of the vacuum cleaner. This is lalso true of residence work.
Schools, department stores and manufacturing buildings con-
tain very little floor space covered with carpets, and in buildings
of this chcaracter the cleaning of bare floors is of the greatest
importance. In such cases the efficiency of the carpet renovator
can be sacrificed to a more efficient and economical operation of
bare floor renovators.
In a building where carpet cleaning is an important function
of the cleaning system, the selection of the carpet renovator is
most important. Of all the various types of carpet renovators
discussed in Chapter III, only two need to be considered. Type
A and Type F. Of these. Type A is superior in all respects
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SELECTION OF CLEANING PLANT 181
except the picking up of large litter, tand, unless the charactier
of the material to be removed contains a large amount of m'ate-
rial which can be picked up by Type F renovator that will not
pass Type A, Type A renovator should always be used. Even
when Type F renovators are desirable, the writer considers that
the plant should still contain some Type A renovators for use
in places where this unusual litter will not be encountered.
Among the bare floor renovators, described in Chapter IV,
only the one having a felt face, curved to permit its running
over the dirt, is worthy of serious consideration. This renovator
requires an inlet or vacuum breaker to keep same from sticking
to the surface cleaned, the extent of such opening being
dependent on the vacuum maintained in the carpet renovators,
as explained in Chapter VII.
When carpet cleaning is considered as of secondary impor-
tance to bare floor cleaning, the degree of vacuum maintained
at the separators may be reduced to that which will produce a
vacuum of 1 in. mercury at the bare floor renovator, allowing
the vacuum maintained at the carpet renovator to be what^
ever the conditions of hose and pipe line will produce. Under
such conditions, the area of the inrush or vacuum breaker in
the bare floor renovator may be reduced considerably.
The use of brush renovators is dependent on the capacity of
the air exhauster supplied, as explained in Chapter VI. If it
is decided that brush renovators are necessary, then the *4arge
volume" exhauster must be installeA The advisability of such
installaition is dependent on the time allowed for cleaning and
the cost of the operators. In residences and small buildings
where the cleaning operations can be done with one or even
two domestics or laborers, very little, if any, saving in the wages
of operators can be effected by increasing the rate at which the
cleaning can be done. In such buildings a small-volume plant
will be the most economical in first cost and operation. If such
a plant is installed, the brush renovators should be omitted.
In cases where bare floor cleaning is the principal function
of the cleaning system the extra quantity of air at the low
vacuum necessary will not require much larger expenditure of
power than that needed by the small-volume plants when
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182 VACUUM CLEANING SYSTEMS
maintaining sufficient vacuum for effective carpet cleaning and
brush renovators sihould be provided with srystems of this char-
acter.
Hose. — In Chapter YI it is shown that when carpet reno-
vators are operated efficiently in combination with bare floor
renovators, lj4-iii- hose will produce the best results with the
lowest expenditure of power at the hose cock. In Chapter VII
it is shown that with pipe lines of ordinary length 1^-in. hose
also gives the best results, with the least expenditure of power
at the separator, but that in cases of exceedingly long pipe
lines, 1-in. hose will be the most economical. In a system where
baire fl>oor cleaning is the principal function, the vacuum to
be maintaineed at the carpet renovator is no longer considered,
and for such systems the largest hose which can easily be han-
dled will cause the least hose friction and require the lowest
vacuum at the hose cock. It is, therefore, the most economical
to use on such a i^stem. The author does not recommend the
use of a hose larger than 1^-in. diameiter for this type of
plant
The proper hose sizes, therefore, will be: For ordinary
buildings where carpet cleaning is important, l^^-in. diameter.
For installations with unusually long lines of piping, where
carpet cleaning is important, 1-in. diameter.
For all systems where carpet cleaning is of secondary impor-
tance, lj4-in. or 1^-in. diameter.
Pipe Lines. — Pipe linei^ should always be as large as pos-
sible without reducing the velocity in same below 40 ft. per
second, as explained in Chapter VII.
Separators. — The type of separator to be used is dependent
on the type of vacuum producer adopted. Where reciprocating
exhausters are used, or other type of exhauster where there is
rubbing contact between the moving parts and the dust, the
combination of a wet and dry separa4x>r is recommended. When
rotary or centrifugal exhausters having close clearances are
used, total separators with bags are recommended. When ex-
hausters with large clearances are operated, partial separators
are satisfactory.
The use of any form of apparatus contemplating the adoption
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SELECTION OF CLEANING PLANT 183
of a satisfactory scrubbing system is not considered advisable,
as the author believes that sepaim.tors for handling water will be
improved before scrubbing becomes commercially successful.
Changes in the existing separators can be made wlien satisfac-
tory scrubbing appliances are placed on the market, at no
greater expense than would be necessary to bring up to date
any of the present systems for handling water.
Vacuum Producers. — The selection of the vacuum producer
is dependent on the degree of vacuum that must be maintained
to effectively operate the system selected. For the operation of
a system where carpet cleaning is the principal function and
lj4-in. hose is used, the vacuum required at the producer will
be from 6 in. to 9 in. mercury. Inspection of the eflSciency
curves of the various types of vacuum pToducers, given in
Chapter IX, shows that the two-impeller rotary pump has the
highest efficiency at this vacuum.
. For the operation of systems where carpet cleaning is the
most important function and 1-in. hose is found to be the most
economical, 14 in. to 15 in. of vacuum at the vacuum producer
is necessary, and efficiency curves, given in Chapter IX, show
that the piston pump is the best suited for such service.
For the operation of a system where carpet cleaning is of
secondary importance a vacuum at the producer of from 2 in.
to 4 in. of mercury wiU be sufficient. For this work, the multi-
stage or even single-stage centrifugal fan is practically as effi-
cient as the two-impeller rotarj^ and will be lower in first cost
and cost of mainten'ance. Either of the above mentioned vacuum
producers are satisfactory for operating a system of this type.
Control. — Every system of more than one-sweeper capacity
in whicih a displacement type of exhauster is used should be
provided with some means of economically controlling the
vacuum at the producer. On one^sweeper plants an automatic
starter which will stop the motor when the vacuum reaches a
point 2 in. above that required and start same when the vacuum
drops to 1 in. below that required is convenient, buit not
necessary.
For piston pumps and all other displacement pumps fitted
with eduction valves, an unloading device, which closes the
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184 VACUUM CLEANING SYSTEMS
suction when the necessary vacuum is exceeded, is the least
expensive to install and gives very good economy when the
demand on the plant is fairly continuous during the time it is
in operation. "Where the service is intermittent and required
at nearly all hours, the Cutler Hammer control, described in
Chapter X, is the most economical.
With displacement exhausters having no eduction valves,
the by-pass type of WHitrol is satisfactory where the service
is continuous, but is not as economical, as the unloader used
with producers having eduction valves and the Cutler Hanmier
control is more efficient under all conditions of service. Cen-
trifugal exhausters need no control, as vacuum control is an
inherent feature of these machines.
Summing up the subject, we can divide the vacuum cleaning
systems into four classes, each of which requires a different
selection of appliances. They are as follows :
Class I. — Plant for residence or small office or departmental
building, to be not more than one-sweeper capacity.
Eenovators: See list given for ** small volume'* plant. Chap-
ter IV.
Hose: lj4-iii- diiameter.
Separator: Centrifugal, dry, with bag or screen.
Vacuum Producer: Two impeller, rotary, alternate centrifu-
gal fan. Capacity, 30 cu ft. of free air per minute, 4 in.
vacuum at producer.
Control: Automatic starter, operated by vacuum.
Size of motor: 5^ to 1 H. P.
Class 2. — Large office or departmental building where car-
pet cleaning is important and pipe lines are of reasonable
length.
Renovators: See list given for ** large volume" plant, Chap-
ter IV.
Hose: lj4-iii- diameter.
Separator: Centrifugal, dry, with bag or screen.
Vacuum Producer: Two impeller, rotary. Capacity, 70 cu.
ft. of free air per minute for each sweeper of plant capacity at
7 in. to 9 in. vacuum.
Size of motor: 2J4 H. P. per sweeper capacity.
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SELECTION OF CLEANING PLANT 185
Control: Cutler Hammer.
Class 3. — Large building or group of buildings whert carpet
cleaning is important and long lines of piping are necessary.
Renovator: See list for *' large volume'' plants, Chapter IV.
Hose: 1-in. diameter.
Separators: One centrifugal dry and one wet.
Vacuum Producer: Piston type pump. Capacity, 45 cu. ft.
of free air per minute for each sweeper of plant capacity at
14 in. vacuum.
Size of motor: 4 H. P. for each sweeper of plant capacity.
Con'trol : Automatic unloader for continuous service. Cutler
Hammer for intermittent work at all times.
Class 4. — Large or small plant where carpet cleaning is not
an important function of the cleaning system.
Renovators: Same as for Class 3.
Hose: Ij/^ in. or 1^ in.
Separators : One centrifugal, dry, with or without bag, accord-
ing to type of exihauster adopted.
Vacuum Producer: Centrifugal fan or two-impeller rotary
pump.
Capacity: 70 to 90 cu. ft. of free air per minute for each
sweeper of plant capacity, with a vacuum of from 2 in. to 3 in.
mercury.
Size of motor: 1 to 2 H. P. for each sweeper of plant
capacity.
Control: With centrifugal fan, none; with pump. Cutler
Hammer.
It is interesting to note that to produce the most efficient
plant for all of the four cases named, all of the various types
of vacuum cleaning systems which have come into general use
have to be operated each under its mo<rt favorable conditions
and the engineer should select his plant to best fulfill the condi-
tions of the special case at hand, just afl he would select his
prime mover for an electric generating plant according to its
size and location. There should be no more reason why any
one of these systems should attempt to fulfill the requirements
of every installation than there would be for a manufacturer
of steam engines to attempt to use the same type of engine to
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186 VACUUM CLEANING SYSTEMS
drive a generator under all oonditiiHis. The writer believes that
this condition will soon be realized by all mannfactai^rs of
vacnnm cleaning systems and that they will endeavor to install
apparatus of the type best suited to the conditions to be met in
each case.
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CHAPTER XIII.
Tests.
Having decided on the type of vacuum cleaning system that
is best suited to the conditions of the particular building in
which it is to be installed, it then becomes necessary to ascer-
tain what are the tests necessary to determine whether the
installation will produce the desired results.
If the installation is one in which carpet cleaning is impor-
tant and the plant is of more than one-sweeper capacity, the
exhauster must be of sufficient capacity to produce a vacuum of
not less than 4 in. mercury at a carpet renovator attached to
any inlet on the piping system, when the planrt: is operating
other renovators of any type attached to any of the other inlets
corresponding to one less than the total sweeper capacity of the
system.
When hose lengths as short as 25 ft. can be used on any or
all of the outlets, it has been demonstrated in Chapter VII that
an air remioval of 70 cu. ft. of free air per minute for each
sweeper of plant capacity is necessary, no matter what size of
hose is used. It was also shown that where pipe lines are very
long and it is possible to always use 100 ft. of hose, efficient
cleaning can be done with less expenditure of power with an
air displacement of 45 cu. ft. of free air for each sweeper of
plant capacity.
Many mefthods have been recommended for testing a jcleaning
plant. Perhaps the earliest was the maintaining of 15 in. of
vacuum at the vacuum producer with carpet renovators each
attached to 100 ft. of hose, equal in number to the sweeper
capacity of the plant in operation on carpets. Another test is
to attach 100-ft. lengths of hose to inlets on the sorstem, with
the ends wide open, equal in number to the sweeper capacity
of the plant, and require the pump to maintain a vacuum of
15 in. mercury.
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188 VACUUM CLEANING SYSTEMS
Both of these tests were recommended for use on plants
where 1-in. diameter hose wtas provided and the results are
dependent largely on the size and length of ttie piping system.
With an average-sized system, the first test will require an
exhaustion of approximately 25 cu. ft. of free air per renovator
per minute if Type A renovators are used. The second test
will require an exhaustion of approximately 50 cu. ft. of free
air per open hose per minute. Neither of these tests will
insure a plant of sufficient capacity to do effective cleaning
where 25-ft. lengths of 1-in. hose can be used or if larger bore
than 1-in. hose be used.
If these tests are required with bores larger than 1-in. diame-
ter and the vacuum is maintained the same as before, air ex-
haustion with lj4-iJi. open hose will be approximately 70 cu. ft.
of free air per open hose, and with lyi-in, hose, approximately
150 cu. ft. per open hose, while, if carpet renovators be used,
the vacuum at the renovator would be from 7 to 9 in. of mer-
cury. In either case, the vacuum required to be maintained at
the separators is higher than is necessary to produce economical
cleaning with either 1^4 -in. or IJ^-in. hose.
Tests with carpet renovators attached to 100 ft. hose lines in
number equal to the capacity of the plant, and a vacuum of
4^ in. of mercury at the renovator will result in an exhaustion
below that necessary to produce efficient cleaning when bare floor
renovators and carpet renovators with shorter hose lines are
used, as is likely to occur in lactual practice.
Again, open hose tests require a variable length of hose to
be used in order to obtain the same air quantity with the proper
vacuum at the separator for economical operation.
If 70 cu. ft. of air is desired, as in the ease of Class 2 plant
(Chapter XII), the hose lengths should be:
50 ft. 1 in. diameter. 12 in. vacuum at separator.
75 ft. Ij4 ill- diameter. 9 in. vacuum at separator.
125 ft. 1J4 in. diameter. 6 in. vacuum at separator.
Any of these lengths would give satisfactory cleaning with
one carpet renovator in use, together with sufficient bare floor
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SELECTION OF CLEANING PLANT 189
renovators to equal the capacity of the plant. This is a pos-
sible condition in any plant.
Another metihod of testing is to measure the actual air passing
through a given length of hose and require suflftcient vacuum
at the separator to produce this flow. This method is open to
the objection that variation in the size of the hose will result in
considerable variation in the vacuum at the separator and con-
ditions of hose lengths may be suc^h that when carpet reno-
vators are attached to the hose, the vacuum at the renovator
will vary according to the resistance offered to the passage of
the air by the friction in the hose. With the small hose, the
friction will be greatest, and the reduction in the quantity of
air passing the renovator from that passing an open hose will
result in the greatest reduction in friction loss through the hose
and produce the highest vacuum at the renovator. This will
cause a widely different vacuum at the renovator with different
sizes of hose, each of whieih passes the same amount of air with
the end of hose open.
What is desired in cleaning operations is a certain degree of
vacuum at the carpet renovator, with the system operated under
the same conditions that will obtain in practical cleaning, and
with cleaaners of various types attached to hose ends equal in
number to the capacity of the plant.
The most rational system of testing is one in which the actual
conditions of air quantity and vacuum are measured at the hose
ends. This can be obtained by actually attaching cleaning
tools to the hose ends and measuring the vacuum within the
renovator. However, a wide variation in vacuum wiU result
when the renovator is moved along the carpet, and this variation
will be different with different operators and different grades
of carpet to such an extent as to render it impossible to actually
meet any reequirements that may be specified, unless a con-
siderable variation in vacuum is permitted.
It is also possible for an operator to become so expert in the
manipulation of the renovators as to be able to meet the speci-
fication requirements with a plant which will not give satisfac-
tory results in actual operation.
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190 VACUUM CLEANING SYSTEMS
The most satisfactory method of testing that has been devised
is the use of an orifice of proper size fixed to the hose end and
measure the vacuum just inside of this orifice. In making
such meajsnirements care must be taken that the tube connecting
to the vacuum gauge is not inserted in such a manner that the
air velocity affects the reading of the vacuum gauge. The
shape of orifice must also be carefully specified, as the round-
ing of the edges of the opening will greatly increase the quan-
tity of air passing a given-sized orificee. The best standard
is a sharp-edged orifice in a thin disk which has a coefficient
of ingress of approxim«itely 65%.
A convenient form of testing appliance based on the orifice
test is the vacometer, manufactured by the Spencer Turbine
Cleaner Company and shown in Fig. 104.
This device consists of a spherical aluminum
casting, with a 1-in. diameter hole on the
equatorial circle, a vacuum gauge being at-
tached to one polar extremity, the other being
attached to the end of the hose. A ring hav-
ing a slip fit is placed around the equatorial
circle in which openings varying from J^-in.
to ^-in. diameter are drilled. By turning
this ring any of the orifices may be made to
register with the opening in the sphere. The
opening to which the vacuum gauge is at-
tached is so located that it is not affected by
the entering air current, and its readings
are not affected by the velocity head.
Experiments with this instrument in con-
^MBTBR**poR^^?SB ncctiou with a Pitot tube show that a 5^ -in.
VACumf ^CLBAN? diamctcr orifice is equivalent to a Type A
iNo SYSTEMS. carpet renovator, a 5/8-in. orifice to a Type
F renovator and a %-in. orifice to a bare floor renovator.
With instruments of this type equal in number to the ca-
pacity of the plant in sweepers, attached to the ends of the
cleaning hose, it is possible to obtain uniform conditions equal
to the average results that will be obtained in actual practice
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SELECTION OF CLEANING PLANT 191
with renovators attached to the hose, without the possibility
of expert manipulation of the renovators affecting the results.
The proper .orifice to be used in each vacometer during the
test wiU vary with the "Character of the service for which the
plant is designed, and the author recommends the following
for each of the classes of plants described in Chapter XII:
Class 1. 2-in. mercury, with j4-in. orifice, maximum length
of hose to be used in actual cleaning.
Class 2. One-half the inlets j4-in. orifice, 4.5 in. mercury at
one orifice attached at end of longest hose desired to use in
practice, the remaining j^-m. outlets on shorter hose lengths.
The other half of inlets to have %-m. orifices open at same
time, with longest hose on one-quarter of total inlets and shortest
on the balance.
Class 3. All inlets on long hose, one-ihalf with 3^2 -in. orifice,
balance with ^ in.
Class 4. All inlets to have ^-in. orifice and 1 in. vacuum at
vacometer, all hose lines maximum length.
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CHAPTER XIV.
Specifications.
Before the engineer begins to prepare his specifications for
a proposed vacuum cleaning system, he will naturally consider
carefully the conditions to be met in the particular installation
contemplated. Having considered these conditions, he can
readily determine the type of system that will operate most
eflSciently and economically under such conditions. It is, there-
fore, natural to assume that the best interests of his clients
can be obtained by confining his specifications tx) apparatus of
the type giving the most efiicient results for the special condi-
tions to be met. However, it is also necessary to study the appar-
atus on the market to determine if there is a sufficient number
of manufacturers producing the pfirticular type of apparatus
specified to insure healthy competition and reasonable bids.
It becomes necessary, therefore, to examine , the various
systems offered by the manufacturers in order to determine what
competition can be obtained.
Apparatus for Class 1 or Class 2, if confined to the positive
displacement rotary exhausters of the two-impeller type, can
be obtained from at least seven manufacturers. If the centri-
fugal fan is included, at least three other manufacturers can
be considered and in either case a healthy competition be had.
If apparatus of Class 3 is desired, it can be obtained from
at least three manufacturers. A few years ago more manu-
facturers of systems of this type were in the market. Some
of these have dropped out, owing to the comparatively limited
field for this apparatus. However, there are still enough manu-
facturers in the field to insure competition.
Apparatus of Class 4 has been especially manufactured by
one company. However, any of the manufacturers of centri-
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SPECIFICATIONS 193
fugal fan type of apparatus can easily meet the specification
requirements for apparatus of the character.
It is, therefore, evident that the specification of apparatus of
the type best suited to any particular installation will not
result in lack of competition, and such a procedure would appar-
ently be justified.
There are installations, such as those for public buildings,
where it may be advisable from an administrative standpoint
to allow the widest competition possible. In such cases the engi-
neer can secure the best results for his clients by so drawing his
specifications as to include all types of apparatus, fixing care-
fully the test requirements to be met and requiring each bidder
ito state in his proposal the amount of power required to operate
his apparatus under full load, three-quarter load and half-load
conditions, and to base the award of the contract on an evalua-
tion basis.
To determine what the basis of this evalution shall be it is
first necessary to ascertain the length of time the plant will be
operated at each of the loads specified and find the annual
cost of a unit of power to operate the plant. Assuming the
plant has a life of ten years, we can charge 10% depreciation,
add to this 5% for interest on the investment and 1% for insur-
ance. We can capitalize the saving in power at 16% and use
this amount as a basis for evaluation.
As an example, assume one bidder guarantees a power con-
sumption of 1 K. W. less at full load, 1.25 K. W. less at three-
quarters load and 0.75 K. W. more at half load than a lower
bidder. Assume the plant will operate 500 hrs. per year at full
load, 200 hrs. at three-quarters load and 300 hrs. at half load.
The total kilowatt hours saved by the more economical plant
will be :
FuU load 500X1= 500
Three-quarter load 200X1.25= 250
Total saving 750
One-half load, 300X0.75= 225
Net saving (K. W. Hr.) 525
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194 VACUUM CLEANING SYSTEMS
If power costs 5 cents per K. W. Hr. the yearly saving will
be $26.25, which, capitalized at 16%, will equal $164.00. This
is the amount which the owner would be justified in paying for
the more economical plant above the price asked for the
ciheaper, but less economical, system.
In order to guard against any bidder guaranteeing a lower
power consumption than he ean actually show on test, it is
necessary to impose a penalty for failure to meet the guarantee
which is in excess of the increase in price shown to be justified
by the evaluation.
The author recommends that this penalty be made not less
than 150% of the increase in price shown by the evalution.
Actually, the owner will not lose by the less efficient plant any
more than the amount shown by the evaluation if 'he junks the
plant at the end of ten years. However, it is more than likely
that he will either use it for a longer time or will be able to
realize something for the plant when it is displaced. The in-
creaaed penalty, therefore, is justified, and it is absolutely
necessary to make this penalty greater than the increased value
to prevent the bidder guaranteeing a power consumption lower
than he can show on test.
The following pages contain sample specifications for appar-
atus of each of the four classes of systems described in Chap-
ter XII and a specification permitting the widest competiftion,
with evaluation and penalty clauses.
CLASS I.
Plant fob REsroENCE or Small Office Building of One-
Sweeper Capacity.
1. Oeneral Description, The work included in this specifica-
tion shall be the installation of a complete vacuum cleaning
system for the removal of dust and dirt from rugs, carpets,
floors, stairs, furniture, Shelves, walls and other fixtures and
furnishings throughout the building, and for conveying said
dust and dirt to suitable receptacles loeaited where shown,
together with all of the necessary cleaning tools, hose, piping.
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SPECIFICATIONS 195
separators, exhauster, motor, etc., as hereafter more fully speci-
fied.
2. Exhauster, The exhauster in all of its details shall be made
of the best materials suitable for the purpose and shall be of
approved design and construction, and may be either of the
positive displacement (rotary) or of the multi-stage fan type.
3. Rotary Exhauster, The rotary displacement exhauster
shall be either of the two-impeller type or of type having single
impeller without sliding vanes revolving without friction con-
tact with case and with oscillating follower.
4. Exhausters fitted with sliding blade or blades will not be
acceptable.
5. All parts of the exhauster Shall be rigid enough to retain
their shape when the machine is working under maximum-load
conditions.
6. The impellers must be machined all over and must be of
such shape and size that they will revolve freely and not touch
each other, the follower, or the casing (cylinder) in which they
are placed, but the clearance must be of the least possible
amount consistent with successful operation.
7. The shafts must be of steel with the journals ground to
size.
8. The journal boxes must be long and rigidly supported by
the headplates and placed far enough from the headplates to
allow the placing of proper stuffing boxes on the shafts.
9. The shafts of two impeller exhausters must be connected
by wide-faced steel gears, cut from the solid and securely fast-
ened to the shafts. Follower shaft on single impeller exhauster
to be connected to impeller shaft by crank and connecting rod.
The gears shall run in suitable oil-tight gear boxes that shall be
fitted with adequate and suitable means for lubrication.
10. Centrifugal Fan Type. The centrifugal fan exhauster to
be 30 proportioned and constructed as to handle the volume of
air required at the specified vacuum with the least possible loss.
The housing shall be of cast iron or aluminum, made in sections.
The housing must be air-tigtht.
11. The fan wheels to be constructed of steel or other metal
of ihigh tensile strength, properly reinforced, and, if cast, must
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196 VACUUM CLEANING SYSTEMS
include hub and arms complete in one piece. If the fan wheels
are built up, they must be strongly riveted to cast-iron, steel or
brass hubs or spidera.
12. The fan wheels are to be secured to shaft with a feather
and set screws, or with left-hand screw.
13. The shaft of fan exhauster may be vertical and the wheels
so mounted that their weig'ht will equalize or partly equalize the
end thrust, or the end thrust may be balanced by the magnetic
pull of the armature. Shaft may be horizontal and end thrust
taken care of with ball-bearing thrust rings.
14. The journal boxes for all of the above named types of
exhausters shall be of the design best adapted for the purpose
and must be fitted with first-class approved continuous lubri-
cating devices, either sight feed, ring oiler, or any other kind
best suited for the work or design of apparatus used.
15. Cooling, The rotary type of exhauster must be provided
with the necessary water connections to properly seal and cool
the pump. Fan type of exhauster must be designed to operate
continuously without a rise of temperature over 100° F. above
room temperature.
16. Speed. Rotary exhausters shall not exceed a peripheral
speed of 1,100 ft. per minute at tips of impellers.
17. Centrifugal fans shall not exceed peripheral velocity of
22,000 ft. per minute w^hen running under specified full-load
conditions.
18. Mounting. The exhauster, motor and separators shall be
mounted as a unit on suitable cast-iron base plate, either
mounted on legs or resting on the bas.ement floor.
19. Dnve. The exhauster shall be driven by an electric motor,
which may be direct connected to the exhauster sihaft or be
operated with an oak-tanned leather belt, or by cut gear-
ing. Belt and gearing are to be of ample size and strength for
their work and must run without undue noise or wear. Means
shall be provided to take up the slack of the belt. Fur-
nisih and place a suitable metal guard over belt and pulley
wheels that shall prevent oil being splashed outside of the base
plate and prevent clothing being caught.
20. If the exhauster is operated through cut gearing, the gear-
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SPECIFICATIONS 197
ing must be inclosed in an oil and dust proof case, which shall
be fitted with means for copious and continuous lubrication of
same.
21. Finish, The air exhauster and motor and the base plate
shall be finished in a first-class manner, filled, rubbed down and
painted at least one coat at the shop, and after installafion shall
receive two more coats, finishing tint to be as directed.
22. Electric Motor, Motor to be of such size that when oper-
ating under test conditions it will not be under less than three-
fourths nor more than full-load condition. It is to be of stand-
ard make, approved by the architect.
23. Motor to be wound for .... volts direct current.
24. Armature to be of toothed-core construction, with wind-
ings thoroughly insulated, and securely fastened in place, and
must be balanced both mechanically and electrically.
25. Commutator segments must be of drop-forged or hard-
drawn copper of highest conductivity, well insulated with mica
of even thickness and proper hardness to insure uniform wear,
and shall run free from sparking or flashing at the brushes
under all conditions of speed. It must be free from all defects
and have ample bearing surfaces and radial depth as provision
for wear.
26. Brushes to be of carbon, mounted on a common rocker
arm for motor, and to have cross-sectional area of not less than
1 square inch for each 35 amperes of current.
27. Brush holders to be of a design to prevent chattering,
with individua;l adjustment in tension for each brush.
28. Bearings to be of an approved self-oiling or ring type.
29. There must be an insulation resistance between motor
frame and field coils, armature windings and brush holders of
not less than 1 megohm.
30. Motor must be capable of standing a breakdown test of
1,500 volts alternating current. Either or both of the foregoing
tests to be applied at the discretion of the architect's agent at
the time of shop tests.
31. The maximum rise in temperature of the motor at a con-
tinuous run (after installation at building) at full speed and
full-rated load for a period of eight hours must not exceed 50*
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198 VACUUM CLEANING SYSTEMS
C. in windings and 55° C. on commutator above the surrounding
atmosphere.
32. Motor to be finished in a first-class manner, filled and
rubbed down and painted two ooats at the shop, and after in-
stallation to have two more coats; finishing tints to be as di-
rected by the superintendent of the building.
33. Tablet. Furnish and mount where directed a polished
slate tablet not less than ^ in. thick, having mounted thereon
one 30^mpere, 250-volt, double-pole knife switch, with enclosed
indicating fuses, and, if displacement ex'hauster is furnished,
one automatic self-starter having butt contacts, cutting out
starting resistance in not less than two steps, starter to be con-
trolled by the vacuum in separator, and shall stop motor when
vacuum rises 2 in. above that required to meet test requirements
and start motor when vacuum falls to that required for working.
34. Electrical Connections. This contractor shall run feeders
from vacuum cleaner panel in switchboard where shown to the
motor panel and make all electrical connections between panel
and motor, etc.
35. All wires are to be run in standard steel conduit, except
those that are so short as to be self-supporting, and these are
to be cord wrapped or otherwise protected. " No wire smaller
than No. 8 to be used.
36. All miaterial and workmanship to be strictly first class.
Electrical work must ^ow an insulation resistance of at least
1 megohm, and to be in strict accordance with the latest edition
of the ''National Electrical Code.''
37. Dust Separator. There shall be one dry separator located
where shown on plans, having a volume not less than 3 cu. ft.
38. The interior arrangement of the separator shall be such,
that no part of same will receive the direct impact of the dust.
Cloth bags or meted screens if used in this separator shall be so
placed that nothing but the very lightest of the dust can lodge
thereon, and that same may be easily cleaned without dismantl-
ing the separator. It must be so constructed that it shall inter-
cept not less than 95% of the dust entering same.
38a. Separator tank shall be constructed with steel shells,
with either oast iron or steel heads, and be fitted with suitable
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SPECIFICATIONS 199
bases or floor stands for support and proper openings for clean-
ing same. Separator shall be fittted with iron-colmnn mercury
gauge reading 50% in excess of operating vacuum.
39. Pipe Lines, All pipe lines shall be of the sizes and run
as indicated on drawings.
40. Pipes, All pipe conveying air is to be standard black
wrougiht-iron or mild-steel screw- jointed pipe, and is to be
smooth inside, free from dents, kinks, fins, or burs. Ends of
pipe to be reamed to the full inside diameter and beveled. Bent
pipe to be used in mains where necessary and where shown on
plans.
41. Care must be taken in erecting pipe to maintain m near-
ly as possible a smooth, uniform bore through all pipe and
fittings.
42. Fittings, All fittings to be tough gray cast iron, free from
blowholes or other defects ; smooth castings in all cases.
43. All fittings on vacuum lines must have inside diameter
through body of same size as pipe bore, and all fins, burs, or
rough places must be removed.
44. Fittings on v«acuum lines are to be blaick or may be
galvanized.
45. Where space permits, all tees and elbows must have a
radius at center line of not less than 3 in.
46. Horizontal overhead pipes to be supported with substan-
tial pipe hangers spaced not more than 10 ft. ap<art.
47. The hangers must have an approved form of adjustment
and the instructions of the superintendent in regard to securing
hangers to floor construction, etc., above must be carefully
followed.
48. Where exposed pipes pass through walls or floors of fin-
ished rooms they must be fitted with cast-iron nickel-plated
plates.
49. Clean-Out Plugs, Brass screw-jointed clean-out plugs are
to be provided in lines at all turns where indicated on the
drawing. The clean-out plugs to be 2 in. diameter, except in
the IJ^-in. lines, where clean-outs are to be same diameter as
the lines.
50. Exhaust Connection. Exhaust pipe from the exhauster
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200 VACUUM CLEANING SYSTEMS
is to be run up to the basement ceiling and along same into the
smoke breeching beyond damper as directed.
51. Sweeper Inlets. The following number of inlets are to be
provided: Subbasement , basement , first story ,
second story , attic
52. The sweeper inlets are to be fitted with hinged covers or
caps with rubber gaskets arranged to be self-closing when hose
is removed, and those in corridors and lobby arranged to be
opened with a key.
53. Inlets coming through finished walls or partitions are
to be flush pattern..
54. Inlets on risers run exposed against walls are to be set
close up against bead of fittings.
55. If contractor desires to use other form of connection
than above described which is equally satisfactory, same mU^
be submitted to the Architect for approval after award of the
contract.
56. In this specification the word *^ renovator'* is used to
mean that portion of the tool which is in contact with the sur-
faces cleaned; the word **stem," that portion connecting the
renovator and hose; the word ** cleaner" is used, to mean a
complete cleaning tool.
57. The following cleaning tools are to be furnished:
One carpet renovator, with cleaning slot J4 i^- t>y 12 in. long.
One bare floor renovator, 12 in. long, with curved felt-cov-
ered face.
One wall renovator, 12 in. long, with cotton flannel curved
face.
One upholstery renovator, with slot ^ in. by 4 in.
One comer cleaner.
One radiator cleaner.
One hat brush.
One long curved stem about 5 ft. long.
One extension tube about 5 ft. long.
58. The renovators for carpets, bare floors and walls to be
arranged with adjustable swivel joint, so that same can be
operated at an angle with stem from 45° for regular use to an
angle of about 80° for use under or back of furniture and other
similar places. This movable joint to be so arranged that lips
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. SPECIFICATIONS 201
of cleaning tool will always remain in contact with surface
cleaned, and constructed so that fitted surfaces are not exposed
to dust, and the air currents when deflected to impinge only
upon surfaces which are of heavy metal and where such wear
as occurs will not affect the operation and handling of the tool.
59. All renovators and stems are to be as light as is consis-
tent with strength and ability to withstand cutting action of
dust.
60. The lips of carpet renovators and upholstery cleaner to
be of such proportions and form as will prevent injury to the
fabric, and such widths as will reduce to a minimum the stick-
ing of renovator face to the material being cleaned.
61. Stems to be not less than 1 in. outside diameter. Air
passages in swivels to be same diameter as inside of stem. Stem
for use with floor renovators shall be curved near upper end to
form handle and provided with swivel to permit hose hanging
vertical.
62. Stems to be drawn-steel or brass tubing, not less than
No. 21 United States standard gauge thick if steel and not less
than No. 16 Brown & Sharpe gauge thick if brass.
63. Carpet renovators to be made preferably of pressed steel,
as light as possible, or may be made of east iron, brass or
aluminum with iron wearing face.
64. Bare floor renovators shall have renewable elastic wear-
ing face curved in direction of motion when cleaning.
65. All renovators and brushes must be provided with proper
rubber or other appix)ved buffers to prevent marring the wood-
work.
66; Upholstery cleaners are to have inlet slots or openings
of such size and form as to absolutely prevent drawing in
loose covering of furniture.
67. Upholstery and comer cleaners are not to be arranged
for use with stems, but are to have their own handles perma-
nently attached and be provided with hose couplings.
68. All metal parts of renovators and stems are to be fin-
ished, and all except aluminum parts nickel plated.
69. Hose. Furnish 75 ft. cleaning hose in three 25-ft. lengths.
70. The hose to be 1J4 i^i- inside diameter best quality rubber
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202 VACUTOI CLEANING SYSTEMS
hose, reinforced in best manner to absolutely prevent collapse
at highest vacuum obtainable with the exhauster furnished and
to prevent collapse if stepped on. Weight of hose to be not over
12 oz. per linear foot.
71. Couplings for hose to be either slip, bayonet-lock or all-
rubber type, with smooth bore of practically same diameter as
inside of hose. The couplings to have least possible projection
outside of hose dimensions and be well rounded, so as not to
injure floors, doors, furniture, etc.
72. Bayonet joints may have packing waiter, and slip joints
to have permanent steel pieces on ends of hose and brass slip
coupler. All ends of hose at couplings to have outside ferrules
securely fastened in place, or pure gum ends glued to coupling.
Simple conical slip joints slipped into ends of hose without fer-
rules will not be acceptable. All joints must fit together so that
they will not be readily pulled apart
73. Tests. All piping to be tested witti air pressure equal to
5 in. mercury before being concealed in walls and other spaces.
Mercury must not fall more than J4 i^- i^ one-half hour.
74. On completion of plant the pump will be operated with
all outlets closed and, under these conditions, there must be an
interval of not less than 10 min. between the stopping and
starting of the motor by the automatic control, if pump system
is used. And if fan system be used, the power required to
operate the exhauster must not be more than 65% of that re-
quired in capacity test.
75. To test the capacity of the separator, a mixture contain-
ing 6 lbs. of sand, passed through a 50-mesh screen, 3 lbs. of
common wheat flour and 16 lbs. of Portland cement shall be
spread over 50 sq. ft. of floor and picked up with a renovator
attached to the end of 50 ft. of Ij^-iii. hose. The machine shall
be stopped and the material removed from the separator spread
on floor and picked up. This procedure shall be repeated until
the material has been handled four times. If the separator
contains a bag, the same must not be disturbed until after com-
pletion of the capacity test, which will be made with the
material in place in separator, after being picked up the fourth
time.
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SPECIFICATIONS 203
After completion of capacity test, the contents of separator
shall be weighed and if same be a partieil separator it must
contain 95% of the material picked up. If a displacement
miachine is used as a vacuum producer, the separator must pre-
vent the passage of any dust thnough separator, which will be
determined by holding a dampened cloth over pump outlet
during test of apparatus. Said cloth must not show any dust
lodged thereon at end of test.
76. To test the capacity of the plant a standard vacometer,
attached to the end of 75 ft. of cleaning hose shall show a
vacuum of 2 in. mercury with J^-in. diameter orifice open.
77. Test of Cleaning Tools. The plant shall be operated by the
Contractor in the presence of the Architect's representative, and
a test made of each kind of cleaning tool furnished. The tool
shall be attached to a 50-f t. length of hose attached to an outlet
selected by the Architect's representative, and under normal
working conditions each tool must satisfactorily perform the
work for which it was designed. Dust and surfaces to be
cleaned shall be furnished by the contractor.
78. Painting. After the completion of the specified tests, all
exposed iron work except galvanized iron or tinned work in
connection with this apparatus, not specified to be otherwise
finished, shall be primed with paint suitable for surfaces covered,
and then given two additional coats. Machinery shall be painted
as already specified, and all other work shall be given finishing
tints as selected or approved by the architect. Black iron pipe,
etc., shall be given two coats lead and oil of tint directed.
Modifications of Specifications when Alternating Current
is Available. — When alternating current is available, instead
of direct, modify specifications as follows:
23. Motor to be wound for volts, cycle, phase
alternating current.
24. Motor to have rotor of the squirrel cage type.
Omit 25, 26 and 27.
28. To remain as for direct current.
29. There must be an insulation between the starter or pri-
mary windings and the frame of not less than one megohm.
30. 31, and 32. Same as for direct current.
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204 VACUUM CLEANING SYSTEMS
33. Tablet. Furnish and mount where directed a polished
slate tablet having mounted thereon a 30 ampere, 250 volt,
.... pole knife switch with enclosed indicating fuses and, if
displacement type exhauster is furnished, an automatic starter
of the ** across the line" type, operated by vacuum in the
separator which will stop motor when the vacuum in the sepa-
rator rises 2 in. -above that required to meet test conditions, and
start exhauster when vacuum reaches working range.
CLASS 2
Plant for Large Office Building Having Pipe Lines of
Moderate Length.
1. Same as for Class 1.
2. Omit centrifugal fan.
3 to 9. Same as for Class 1.
Omit 10 to 13.
14 and 16. Same as for Class 1.
15. Omit centrifugal fan.
Omit 17 and 18.
18a. Base Plate, Foundation, etc. Provide suitable base
plate to rigidly support the exhauster and its motor as a unit,
which shall be large enough to catch all drip of water or oil.
Provide a raised margin and pads for feet of exhauster frame,
motor, and anchor bolts, high enough to prevent any drip from
getting into the foundation or on the floor.
18b. Provide suitable foundation of brick or concrete, to
which the base plate shall be firmly anchored. The foundation
shall be built on top of the cement floor of the basement, which
shall be picked to afford proper bond for the foundation.
18c. Construct the foundation of such a height as to bring
the working parts of the machine at the most convenient level
for operating purposes. Exposed parts of the foundation to be
faced with best grade white enameled brick. If the base plate
does not cover the foundation, the exposed top surface is to be
finished with enameled brick, using bull-nose brick on all edges
and comers.
19 to 23. Same as for Class 1.
23a. The guaranteed efficiency of motor shall not be less
than 78% at half load and not less than 84% at full load.
24 to 32. Same as for Class 1.
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SPECIFICATIONS 205
32a. Motor shall be subject to shop test to determine effi-
ciency, heating, insulation, etc. Manufacturer's certified test
sheets of motor giving all readings taken during shop tests,
together with calculated results, must be submitted to the Archi-
tect for approval before motor is shipped from factory.
33. Rheostat. Furnish and install where shown, upon a
slate panel^ hereinafter specified, a starting rheostat of proper
size and approved made, designed for. the particular duty it has
to perform. It must have an automatic no-voltage and over-
load release. All resistance for rheostat is to be placed on the
back of the tablet. Contacts must project through board to
front side. All moving parts must be on front of board.
33a. Tablet, Furnish and place where shown, a slate tab-
let not less thian ^ in. thick, supported by a substantial angle
iron frame, so placed that there will be a space of not less than
4 in. between the wall and back of resistance. Mount on this
tablet one double-pole, 250-volt knife switch, with two 250-volt
inclosed fuses and one starting rheostat, as specified hereinbe-
fore. The connections shall be on the back of the tablet. The
space between the column and the tablet shall be inclosed with
a removable diamond-mesh grill of No. 10 iron wire in channel
frame.
34, 35, 36. Same as for Class 1.
36a. Automatic Control. Suitable means shall be provided in
connection with the rotary exhausters that will maintain the
vacuum in the separators within the limit of the machine at
point found to be most desirable, irrespective of the number of
sweepers in operation.
36b. Controller shall consist of a suitable means provided in
the exhauster, or as an attachment thereto, which will auto-
matically throw the exlhauster out of action by admitting atmos-
pheric pressure to the exhauster only, but not to the system
whenever the vacuum in the separators rises above the point
considered desirable, and throw the exhauster into action when
the vacuum falls below the established lower limit.
36c. Vacuum Breaker. In addition to the controlling devices
above specified there shall be placed in the suction pipe to the
exhauster an approved positive-acting vacuum breaker having
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206 VACUUM CLEANING SYSTEMS
opening equivalent to the area of 1-in. diameter pipe and set
to open at 10 inches vacuum.
(If plant is to be run for long periods without much load, as
in a hotel, omit 36a, b, c, and substitute) :
36d. Automatic Control, An approved type of controller for
maintaining practically a constant vacuum by varying the
speed of the motor driving exhauster arranged to permit the
operation of the motor continuously at any speed between full
speed and stop, so long as there be no change in vacuum and
which will increase speed whenever vacuum falls and reduce
speed whenever vacuum rises, must be provided.
37. Dust Separator. There shall be one dry separator located
where shown on plans, having a volume of not less than 3 cu. ft.
for each sweeper of plant capacity.
38. The interior arrangement of the separator shall be such
that no part of same will receive the direct impact of the dust.
Cloth bags or metal screens, if used in this separator, shall
be so placed that nothing but the very lightest of the dust
can lodge thereon, and that same may be easily cleaned without
dismantling the separator. It must be so constructed that it
will intercept all of the dust entering same.
38a to 56. Same as for Class 1.
56a. Tool Cases. Furnish approved hardwood cabinet-fin-
ished cases for cleaning tools. Each case to be made as light
as possible and of convenient form for carrying by hand and
provided with a complete set of cleaning tools, each securely
held in its proper place, and fitted with lock and key, clamps,
and conveniently arranged handles.
57. Each case shall contain the following:
One carpet renovator, with slot J4 i^- by 1^ in.
One bare floor renovator, 15 in. long, with curved felt-cov-
ered face.
One wall brush, with skirted bristles, 12 in. long and }i in.
wide.
One hand brush, with hose connections at end, 8 in. long,
2 in. wide.
One 4-in. round brush for relief work.
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SPECIFICATIONS 207
One upholstery renovatwr.
One comer cleaner.
One radiator tool.
One curved stem about 5 ft. long.
One extension tube 5 ft. long.
At least one hat brush with the system.
58 to 64. Same as for Class 1.
64a. All brushes to be of substantial construction, with best
quality bristles set in close rows and as thick as possible, skirted
with rubber, leather, or chamois skin, so that all air entering
renovator will pass over surface being cleaned.
65 to 68. Same as for Class 1.
69. Hose Racks. Furnish and properly secure in place, where
directed, .... hose racks in basement, .... each in first and
second stories ( . . . . racks in all). The racks to be constructed
of cast iron, galvanized or enamel finish, and each rack to be
suitable for holding 75 ft. of hose of required size.
69a. Hose. There must be furnished with each hose rack 75
ft. of noncolliapsible hose in three 25-ft. lengths.
70 to 73. Same as for Class 1.
74. On completion of the plant the pump will be operated
with all outlets closed, and, under this condition, the power
consumption must not be more than 50% of that required
under test conditions.
75. Test of Separators. At each of ^points, near out-
lets on different risers selected by the architect's representa-
tive, the contractor shall furnish and spread on the floor, evenly
covering an area of approximately 50 sq. ft. for each outlet, a
mixture of 6 lbs. of dry sharp sand that will pass a 50-mesh
screen, 3 lbs. of fine wheat flour and 6 lbs. of Portland cement.
75b. Fifty feet of hose shall be attached to each of the
outlets, and the surfaces prepared for cleaning shall be cleaned
simultaneously by operators provided by the contractor until
all of the sand, flour and Portland cement has been taken up,
when the exhauster shall be stopped and the dirt removed from
the separator and spread on the floor again, and the operation
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208 VACUUM CLEANING SYSTEMS
of cleaning repeated until the mixture has been handled by the
apparatus four times.
The bag contained in the separator must not be disturbed
until after completion of the capacity test, which will be made
with material in place in the separator after being picked up
the fourth time. After completion of the capacity test the
contents of separator will . be removed. During test of sepa-
rators a dampened cloth will be held over the exhaust from
pump. If such cloth indicates dirt passing through the sepa-
rator, same will be rejected.
76. To test the capacity of the plant, one hose line 100 ft.
long shall be attached to inlet farthest from the separator with
standard vacometer, with >2-in. opening in end of hose
hose lines shall be attached to other outlets, each with 50 ft.
hose and vacometers in end of hose, .... vacometers having
^-in. opening and .... vacometers having %-in opening.
Under these conditions 4 in. mercury must be maintained in
vacometer at end of 100 ft. of hose.
77 and 78. Same as for Class 1.
Modifications of Specifications when Alternating Current
is Available. — ^When alternating current is available, instead of
direct, modify specifications as follows:
23. Motor to be wound for .... volts, .... cycle, .... phase
alternating current.
23a. Bidders must name efficiency and power factor of motor
at one^half and full load.
24. Motor to have phase-wound rotor with collector rings for
insertion of starting resistance.
Omit 25, 26 and 27.
28. Same as for direct current.
29. There must be. an insulation between the starter or pri-
mary windings and the frame of not less than one megohm.
30. 31, 32, 32a. Same as for direct current.
33. Rheostat. Furnish and install an approved hand-starting
rheostat for inserting resistance in rotor circuit in starting, of
proper size to insure the starting of motor in not exceeding
15 seconds without overheating.
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SPECIFICATIONS 209
33a. Same as for direct current, except that switch must be
either three- or four-pole, according to current available.
Omit 36d with alternating current machine.
CLASS 3
Large Installation with Unusually Long Pipe Lines.
1. Same as for Class 1.
2. Exhauster shall be of the reciprocating piston type.
3. The piston type of exhauster shall be double acting and
so designed that the cylinder clearance shall be reduced to a
minimum, or suitable device shall be employed to minimize the
effect of large clearance.
4. The induction and eduction valves may be either poppet,
rotary, or semi-rotary, and shall operate smoothly and noise-
lessly.
5. The piston packing shall be of such character as to be
practically air tight under working conditions and constructed
so that it will be set out .with its own elasticity without the use
of springs of any sfort. If metallic rings are used, they must
fill the grooves in which they are fitted, both in width and
depth, and must be concentric; that is, of the same thickness
throughout. The joint in the ring or rings to be lapped in
width but not in thickness, and if more than one ring is used
they are to be placed and doweled in such position in their
respective grooves so that the joints will be at least one-fourth
of the circumference apart.
6. The piston shall have no chamber or space into which air
may leak from either side of the piston. All openings into
the body of the piston must be tightly plugged with cast-iron
plugs.
7. The piston rod stuffing box to be of such size and depth
that if soft packing is used it can be kept tight without undue
pressure from the gland. If metallic packing is used, it must
be vacuum tight without undue pressure on the rod. Proper
means shall be provided for the continuous lubrication of the
piston rod.
8. The exhauster of the piston type shall be fitted with an
approved cross-head suitably attached to the piston rod; ma-
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210 VACUUM CLEANING SYSTEMS
chines having an extended pistx>n rod for guide purposes will
not be acceptable.
Omit 9 to 13.
14. Same as for Class 1.
15. Reciprocating piston exhauster shall be provided with
the necessary devices for the removal of the heat generated by
friction and compression, that shall prevent the temperature of
cylinders or eduction chambers rising more than 100° F. above
the surrounding atmosp^here after two hours' continuous oper-
ation under full-load conditions.
16. Speed. Reciprocating exhauster with poppet valves shall
operate at an average piston speed not exceeding 200 ft. per
minute, with rotary valves not exceeding 300 ft. per minute.
Omit 17 and 18.
18a. Base Plate, Foundation, etc. Provide suitable base plate
to rigidly support the exhauster and its motor as a unit, which
shall be large enough to catch all drip of water or oil. Provide
a raised margin and pads for feet of exhauster frame, motor,
and anchor bolts, high enough to prevent any drip from get-
ting into the foundation or on the floor.
18b. Provide suitable foundation of brick or concrete, to
w^hich base plate shall be firmly ancfhored. The foundation shall
be built on top of the cement floor of the basement, which shall
be picked to afford proper bond for the foundation.
18c. Construct the foundation of such a height as to bring
the working parts of the pnaohine at the most convenient level
for operating purposes. Exposed parts of the foundation to be
faced with best grade white enameled brick. If the base plate
does not cover the foundation, the exposed top surface is to be
finished with enameled brick, using bull-nose brick on all edges
and corners.
19 to 23. Same as for Class 1.
23a. The guaranteed efficiency of motor shall not be less than
80% at half load and not less than 85% at full load.
24 to 32. Same as for Class 1.
32a. Motor shall be subject to shop test to determine effi-
ciency, heating, insulation, etc. Manufacturers' certified test
sheets of motor, giving all readings taken during shop test, to-
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SPECIFICATIONS 211
gether with calculated results, must be submitted to the Archi-
tect for approval before motor is shipped from factory.
33. Rheostat, Furnish and install where shown, upon a
slate panel hereinafter specified, a starting rheostat of proper
size and approved make, designed for the particular duty it has
to perform. It must have an automatic no-voltage and over-
load release. All resistance for rheostat is to be placed on the
back of the tablet. Contacts must project through board to
front side. All moving parts must be on front of board.
33a. Tablet. Furnish and place where shown, a slate tab-
let, not less than ^ in. thick, supported by a substantial angle
bar frame, so placed that there will be a space of not less than
4 in. between the wall and back of resistance. Mount on this
tablet one double-pole, 250-volt knife switch, with two 250-volt
inclosed fuses and one starting rheostat, as specified herein-
before. The connections shall be on the back of the tablet.
The space between the column and the tablet shall be inclosed
with a removable diamond-mesh grill of No. 10 iron wire in
channel frame.
34, 35 and 36. Same as for Class 1.
37. Dtist Separators. There shall be one dry and one wet
separator located where shown on drawings. Each separator
shall have a volume of 3 cu. ft. for each renovator of plant
capacity.
38. The separator first receiving the dust shall be a dry
separator, the interior arrangement of which shall be such that
no part of same shall receive the direct impact of the dust.
No screens or cloth bags shall be used in this separator and it
must be so constructed that it will intercept 95% of the dust
entering same.
38a. The second separator must be a wet separator which
may be contained in the base of the machine or consist of a
separate tank.
38b. Wet separatofrs, whether separate from or integral with
the base of the machine, must be provided with an attachment
which will positively mix the air and water, thoroughly break
up all bubbles, separate the water from the air, and prevent
any water entering the exhauster cylinder.
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212 VACUUM CLEANING SYSTEMS
38c. Suitable means must be provided to automatically equal-
ize the vacuum between wet and dry separators upon the shut-
ting down of the exhauster.
38d. The separators must be provided with suitable openings
for access to the interior for inspection and cleaning, and ihe
interior arrangement of the separators must be such that they
may be readily cleaned without dismantling.
38e. All parts of the wet separator tank not constructed of
non-corrosive metal must be thoroughly tinned or galvanized
both inside and outside. The interior of the wet separator
formed in base of exhauster shall be painted with at least two
coats of asphalt varnish or other paint suitable to prevent the
corrosion of same.
38f. Separators must be provided with all necessary valves
or other attachments for successful operation, including a sight
glass for the wet separator, throug»h whieh the interior of the
same may be observed, and an iron-case mercury column read-
ing 50% in excess of operating vacuum, attached to the dry
separator first receiving the dust.
38g. The wet separator shall be properly connected to water
supply where directed and discharge to sewer where shown on
plans.
38h. A running trap with clean-out shall be installed in the
waste line.
39 to 41. Same as for Class 1.
41a. Waste and water pipe, in connection with wet separator
and jacket, except waste pipe below basement floor, to be stand-
ard galvanized wrought-iron pipe or steel screw-jointed pipe
free from burs. Waste pipe below the basement floor is to be
best grade, ** extra heavy'' cast-iron pipe, with lead-oalked
joints.
42 to 45. Same as for Class 1.
45a. Fittings on water lines to be standard galvanized beaded
fittings.
45b. Fittings on waste line above basement floor line to be
galvanized recessed screw-jointed drainage fittings and thoso
below basement floor to be ** extra heavy" cast-iron with hub
joints.
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SPECIFICATIONS 213
46 to 50. Same as for ClasB 1.
50a. The exhaust pipe is to be fitted with an approved first-
class exhaust muffler not less than 12 in. in diameter and 60 in.
high, closely riveted and constructed of galvanized iron not less
than }i in. thick, and in event an exhauster requiring lubricar
tion is furnished, this muffler is to be arranged so that it will
also be an efficient oil separator. Drip connection to be arranged
at bottom of muffler.
51 to 56. Same as for Class 1.
56a. Tool Cases. Furnish approved hardwood cabinet-
finished cases for cleaning tools. Each case to be made as light
as possible and of convenient f orm^ for carrying by hand and
provided with a complete set of cleaning tools, each securely
held in its proper place, and fitted with lock and key, clamps
and conveniently arranged handles.
57. Each case shall contain the following:
One carpet renovator, with slot J4 i^- by 12 in.
One bare floor renovator 12 in. long, with curved, felt-cov-
ered face.
One wall brush, with skirted bristles, 12 in. long and >^ in.
wide.
One hand brush, with hose connection at end, 8 in. long and
2 in. wide.
One 4-in. round brush for relief work.
One upholstery renovator.
One comer cleaner.
One radiator tool.
One curved stem about' 5 ft long.
One straight extension stem 5 ft. long.
At least one hat brush with the system.
58 to 64. Same as for Class 1.
64a. All brushes to be of substantial construction, with best
quality bristles set in close rows and as thick as possible, skirted
with rubber, leather, or chamois skin, so that all air entering
renovator will pass over surface being cleaned.
65 to 68. Same as for Class 1.
69. Hose ,Backs. Furnish and properly secure in place where
directed, hose racks in basement, .... each in first and
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214 VACUmi CLEANING SYSTEMS
second stx)ries ( . . . . racks in all). The racks to be constructed
of cast-iron, galvanized or enamel finish, and each rack to be
suitable for holding 75 ft. of hose of required size.
69a. Hose, There must be furnished with each hose rack 75
ft. of non-collapsible hose in three 25-ft. lengths.
70. Hose to be 1 in. inside diameter of best quality, rubber
hose, reinforced in best manner to absolutely prevent collapse
at highest vacuum obtainable with the exhauster furnished and
to prevent collapse if stepped on. Weight of hose to be not
over 12 oz. per linear foot.
71, 72 and 73. Same as for Class 1.
74. On completion of the plant the pump will be operated
with all outlets closed and, under this condition, the power
consumption must not be more than 50% of that required under
test conditions.
75, To test the capacity of the plant, .... hose lines each
100 ft. long will be attached to outlets on the system and each
hose fitted with a standard vacometer vacometers shall
have 34-in. opening and .... vacometers shall have ?^-in. open-
ing. Under these conditions 4 in. vacuum must be maintained
at vacometers having yz in. opening.
75a. Test of Separators. At each of points, near — —out-
lets on different risers selected by the architect's representative,
the contractor shall furnish and spread on the floor, .evenly cov-
ering an area of approximately 50 sq. ft. for each outlet, a mix-
ture of 6 lbs. of dry sharp sand that will pass a 50-mesh screen,
3 lbs. of fine wheat flour, and 1 lb. of finely pulverized dharcoal.
75b. Fifty feet of hose of size required by. the system shall
be attached to each of the outlets, and the surface or sur-
faces prepared for cleaning shall be cleaned simultaneously by
operators provided by the contractor until all of the sand, flour
and charcoal has been taken up, when the exhauster shall be
stopped and the dirt removed from the dry separator and spread
on the floor again, and the operation of cleaning repeated until
the mixture has been handled by the apparatus four times. If,
after thoroughly flusihing the system at completion of above
run, any dust or mud is found in the cylinder, ports, or valve
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SPECIFICATIONS 215
chambers of the displacement exhauster, or if less than 95%
of the dirt removed is found in the dry separator, it shall be
deemed sufficient ground for the rejection of the separators.
76 and 77. Same as for Cla^ 1.
Modifications of Specifications when Alternating Current
is Available. — When alternating current is available, instead
of direct, modify specifications as follows:
23. Motor to be wound for volts, cycle, phase
alternating current.
23a. Bidders must name efficiency and power factor of motor
at one-half and full load.
24. Motor to have phase-wound rotor with collector rings
for insertion of starter resistance.
Omit 25, 26 and 27.
29. Same as for Class 1, alternating current.
33. Rheostat. Furnish and install an approved hand-starting
rheostat for inserting resistance in rotor circuit in starting, of
proper size to insure the starting of motor in not exceeding
15 seconds without overheating.
33a. Same as for direct current, except switch must be either
three- or four-pole, according to current available.
CLASS 4
Large or Small Plant Where Carpet Cleaning is of Sec-
ondary Importance.
1 to 17. Same as for Class 1.
Omit 18.
18a. Base Plate, Foundation, etc. Provide suitable base plate
to rigidly support the exhauster and its motor as a unit, which
shall be large enough to catch all drip of water or oil. Provide
a raised margin and pads for feet of exhauster frame, motor,
and anchor bolts, high enough to prevent any drip from getting
into the foundation or on the floor.
18b. Provide suitable foundation of brick or concrete, to
which the base plate shall be firmly anchored. The founda-
tion shall be built on top of the cement floor of the basement,
which shall be picked to afford proper bond for the foundation.
18c. Construct the foundation of such a height as to bring
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216 VACUUM CLEANING SYSTEMS
the working parts of the machine at the most convenient level
for operating purposes. Exposed parts of the foundation to be
faced with best grade white enameled brick. If the base plate
does not cover the foundation, the exposed top surface is to be
finished with enameled brick, using bull-nose brick on all edges
and comers.
19 to 23. Same as for Class 1.
23a. The guaranteed efi&ciency of motor shall not be less than
78% at half load and not less than 84% at full load.
24 to 32. Same as for Class 1.
32a. Motor shall be subject to shop test to determine effi-
ciency, heating, insulation, etc. Manufacturers' certified test
sheets of motor, giving all readings taken during shop test,
together with calculated results, must be submitted to the
Architect for approval before motor is shipped from factory.
33. Rheostat, Furnish and install where shown, upon a
slate panel hereinafter specified, a starting rheostat of proper
size and approved make, designed for the particular duty it
has to perform. It must have an automatic no-voltage and
overload release. All resistance for rheostat is to be placed
on the back of the tablet. Contacts must project through board
to front side. All moving parts must be on front of board.
33a. Tablet. Fumis hand place where shown, a slate tab-
let not less than }i in. thick, supported by a substantial angle
iron frame, so placed that there will be a space of not less than
4 in. between the wall and back of resistance. Mount on this
tablet one double-pole, 250- volt knife switch, with two 250-volt
inclosed fuses and one starting rheostat, as specified herein-
before. The connections shall be on the back of the tablet.
The space between the column and the tablet shall be enclosed
with a removable diamond-mesh grill of No. 10 wire in channel
frame.
34, 35 and 36. Same as for Class 1.
36a. Automatic Control. Suitable means shall be provided in
connection with the rotary exhauster that will maintain the
vacuum in the separators within the limit of the machine at
point found to be most desirable, irrespective of the number
of sweepers in operation.
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SPECIFICATIONS 217
36b. Controller shall consist of a suitable means provided
in the exhauster, or as an attachment thereto, which will auto-
matically throw the exhauster out of action by admitting
atmospheric pressure to the exhauster only, but not to the sys-
tem ; whenever the vacuum in the separator rises above the point
considered desirable, and tihrow the exhauster into action when
the vacuum falls below the established lower limit.
36c. In addition to control, a positive vacuum breaker having
an opening equal to 1 in. diameter pipe net for 6 in. of mercury,
must be provided on separator.
36d. If centrifugal fan is used, no control or vacuum breaker
will be required.
37. Furnish one separator having a cubic contents of 4.5 cu.
ft. for each sweeper of plant capacity.
38 to 56. Same as for Class 1.
56a. Tool Cases, Furnish approved hardwood cabinet-fin-
ished cases for cleaning tools. Each case to be made as light
as possible and of convenient form for carrying by hand and
provided with a complete set of cleaning tools, each securely
held in its proper place, and fitted with lock and key, clamps,
and conveniently arranged handles.
57. Each case shall contain the following:
One carpet renovator yi in. by 15 in.
One bare floor renovator, 15 in. long, with curved felt-cov-
ered face.
One wall brush, with skirted bristles, 12 in. long and j4 in.
wide.
One hand brush, with hose connection at end, 8 in. long
and 2 in. wide.
One 4-in. round brush for relief work.
One upholstery renovator.
One comer cleaner.
One radiator tool.
One curved stem about 5 ft. long.
One straight extension stem 5 ft. long.
At least one hat brush with the system.
58 to 68. Same as for Class 1.
69. Hose Backs. Furnish and properly secure in place, where
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218 VACUTOI CLEANING SYSTEMS
directed, .... hose racks in basement, each in first and
second stories ( racks in all). The racks to be constructed
of cast-iron, galvanized or enamel finish, and each rack to be
suitable for holding 75 ft. of hose of required size.
69a. Hose. There must be furnished with each hose rack 75
ft. of non-collapsible hose in three 25-ft. lengths.
70. Hose to be 1^ in. or 1^ in. inside diameter, best quality
rubber hose, reinforced in best manner to absolutely prevent
collapse at highest vacuum obtainable with the exhauster fur-
nished and to prevent collapse if stepped on. Weight of hose
to be not over 12 oz. per linear foot.
71 to 73. Same as for Class 1.
74. On completion of the plant the pump will be operated
with all outlets closed and, under this condition, the power con-
sumption must not be more than 50% of that required under
test conditions.
75. Same as for Class 1.
76. To test the capacity of the plant, .... hose lines each
75 ft. long shall be attached to the inlets, each hose to be fitted
with standard vacometer with %-in. opening. Under these
conditions a vacuum of 1 in. mercury must be maintained in
each vacometer.
77 and 78. Same as for Class 1.
CLASS 5
To Give Widest Competition.
1. Same as for Class 1.
2. Exhauster to be piston, rotary or centrifugal fan type.
3. The piston type of exhauster shall be double-acting and
so designed that the cylinder clearance shall be reduced to a
minimum, or suitable devices shall be employed to minimize
the effect of large clearances.
4. The induction and eduction valves may be either poppet,
rotary or semi-rotary, and shall operate smoothly and noise-
lessly.
5. The piston packing shall be of such character as to be
practically air tight under working conditions and constructed
so that it will be set out with its own elasticity without the use
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SPECIFICATIONS 219
of springs of any sort. If metallic ring:s are used, they must
fill the grooves in which they are fitted, both in width and depth,
and must .be concentric; that is, of the same thickness through-
out. The joint in the ring or rings to be lapped in width but
not in thickness, and if more than one ring is used they are
to be placed and doweled in such position in their respective
grooves so that the joints will be at least one-fourth of the cir-
cumference apart.
6. The piston shall have no chamber or space into which air
may leak from either side of the piston. All openings into the
body of the piston must be tightly plugged with cast-iron
plugs.
7. The piston-rod stuffing box to be of such size and depth
that if soft packing is used it can be kept tight without undue
pressure from the gland. If metallic packing is used, it must
be vacuum tight without undue pressure on the rod. Proper
means shall be provided for the continuous lubrication of the
piston rod.
8. The exhauster of the piston type shall be fitted with an
approved cross-head suitably attached to the piston rod; ma-
chines having an extended piston rod for guide purposes will
not be acceptable.
Insert paragraphs 3 to 15 from specifications for Class 1.
15a. Reciprocating exhauster shall be provided with the nec-
essary devices for the removal of the heat generated by friction
and compression, that sihall prevent the temperature of cylin-
ders or eduction chambers rising more than 100° F. above the
surrounding atmosphere after two hours' continuous operation
under full load conditions.
15b. Speed. Reciprocating exhauster with, poppet valves shall
operate at an average piston speed not exceeding 200 ft. per
minute, with rotary valves not exceeding 300 ft. per minute.
Insert paragraphs 16 and 17 from specifications for Class 1.
Omit 18.
18a. Base Plate, Foundation, etc. Provide suitable base plate
to rigidly support the exhauster and its motor as a unit, which
shall be large enough to catch all drip of water or oil. Provide
a raised margin and pads for feet of exhauster frame, motor,
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220 VACUUM CLEANING SYSTEMS
and anehor bolts, high enough to prevent any drip from getting
into the foundation or on the floor.
18b. Provide suitable foundation of brick or concrete, to
which the base plate shall be firmly anchored. The founda-
tion shall be built on top of the cement floor of the basement,
which shall be picked to afford proper bond for the foundation.
18c. Construct the foundation of such a heighit as to bring
the working parts of the machine at the most convenient level
for operating purposes. Exposed parts of the foundation to be
faced with best grade white enameled brick. If the base plate
does not cover the foundation, the exposed top surface is to be
finished with enameled brick using bull-nose brick on all edges
and comers.
19 to 23. Same as for Class 1.
23a. The guaranteed efficiency of motor shall not be less than
78% at half load and not less than 84% at full load.
24 to 32. Same as for Class 1.
32a. Motors shall be subject to shop test to determine effi-
ciency, heating, insulation, etc. Manufacturers' certified test
sheets of motor, giving all readings taken during shop test,
together with calculated results, must be submitted to the archi-
tect for approval before motor is shipped from factory.
33. Rheostat. Furnish and install where i^own, upon a
slate panel hereinafter specified, a starting rheostat of proper
size and approved make, designed for the particular duty it has
to perform. It must have an automatic no-voltage and overload
release. All resistance for rheostats is to be placed on the back
of the tablet. Contacts must project through board to front
side. All moving parts must be on front of board.
33a. Tablet, Furnish and place where shown, a slate tablet
not less than ^ in .thick, supported by a substantial angle bar
frame, so placed that there will be a space of not less than 4 in.
between the wall and back of r^istance. Mount on the tablet
one double-pole, 250-volt knife switch, with two 250-volt en-
closed fuses and one starting rheo^at, as specified herein-
before. The connections shall be on the back of the tablet.
The space between the column and the tablet shall.be enclosed
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SPECIFICATIONS 221
with a removable diamond-mesh grill of No. 10 iron wire in
channel frame.
34, 35 gud 36. Same as for Class 1.
36a. Automatic Control, Suitable means shall be provided
in connection with the reciprocating and rotary exhausters that
will maintain the vacuum in the separators within the limit of
the machine at point found to be most desirable, irrespective of
the number of sweepers in operation.
36b. Controller shall consist of a suitable means provided in
the exhauster, or as an attachment thereto, which will auto-
imatically throw the exhauster out of action by admitting atmo-
spheric pressure to the exhauster only, but not to the system ; or
that shall cause suction from the system to cease whenever the
vacuum in the separators rises above the point considered de-
isirable, and throw the exhauster into action when the vacuum
falls below the established lower limit.
36c. Vacuum Breaker. In addition to the controlling devices
Above specified, if a reciprocating or rotary exhauster is used,
there shall be placed in the suction pipe to the exhauster an
approved positive-acting vacuum breaker having opening equiva-
lent to the area of 1-in. diameter pipe and set to open at 12 in.
36d. If centrifugal fan is used, no control or vacuum breaker
will be required.
37. Dust Separators. There must be provided at least one
:separator between the pipe lines and exhauster having a volume
of not less than 3 cu. ft. per sweeper of plant capacity. This
separator must be so constructed that no part thereof will re-
ceive the direct impact of the dust. If rotary exhauster is used,
this separator must also contain a bag so placed that only the
lightest dust will reach same and must be arranged to be
readily cleaned without dismantling the separator. If a
centrifugal exhauster is used, this apparatus may or may not
contain a bag, and, if piston pump is used, this separator must
contain no bags or screens whatever. If a piston type of ex-
hauster is installed, an additional separator must be placed be-
tween the first separator and the exhauster. This must be a
wet separator and may be contained in the base of the ma-
chine or consist of a separate tank.
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222 VACUUM CLEANING SYSTEMS
Omit 38.
38a. Same as for Class 1.
38b. Wet separators, whether separate from or integral with
the base of the machine, must be provided with an attachment
which will positively mix the air and water, thoroughly break
up all bubbles, separate the water from the air, and prevent
any water entering the exhauster cylinder.
38c. Suitable means must be provided to automatically equal-
ize ithe vacuum between wet and dry separators upon the shut-
ting down of the exhauster.
38d. The separators must be provided with suitable openings
for access to the interior for inspection and cleaning, and the
interior arrangement of the separators must be such that they
may be readily cleaned without dismantling.
38e. All parts of the wet separator tank (if used) not con-
structed of non-corrosive metal must be thoroughly tinned or
galvanized both inside and outside. The interior of the wet
separator formed in base of exhauster shall be painted with at
least two coats of asphalt varnish or other paint suitable to pre-
vent the corrosion of same.
38f . Separators must be provided with all necessary valves
or other attachments for successful operation, including a sight
glass for the wet separator (if used), throug^h which the interior
of same may. be observed.
38g. The wet separator (if used) shall be properly connected
to ^ water supply where directed and discharge to sewer where
shown on plans.
38h. A running trap with clean-out shall be installed in the
waste line.
39 to 41. Same as for Class 1.
41a. Waste and water pipe, in connection with wet separator
and jacket, except waste pipe below basement floor, to be stand-
ard galvanized wrought-iron or steel screw-jointed pipe free
from burs. Waste pipe below the basement floor is to be best
grade, ** extra heavy'' cast-iron pipe, with lead-oalked joints.
42 to 45. Same as for Class 1.
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SPECIFICATIONS 223
45a Fittings on water lines to be standard galvanized beaded
fittings.
45b. Fittings on waste line above basement floor to be gal-
vanized recessed screw-jointed drainage fittings and those below
basement floor to be *' extra heavy'' cast-iron with hub joints.
46 to 50. Same as for Class 1.
50a. If reciprocating exhauster is used, the exhaust pipe is
to be fitted with an approved first-class muffler not less than 12
in. in diameter and 60 in. high, closely riveted and constructed
of galvanized iron not less than % in. thick, and in event an
exhauster requiring lubrication is furnished this muffler is to
be arranged so that it will also be an efficient oil separator. Drip
connection is to be arranged at bottom of muffler.
51 to 56. Same as for Class 1.
56a. Tool Cases, Furnish .... approved hardwood cabinet
finished cases for cleaning tools. Each case to be made as
lig-ht as possible and of convenient form for carrying by hand
and provided with a complete set of cleaning tools, each se-
curely held in its proper place, and fitted with lock and key,
clamps, and conveniently arranged handles.
57. Each case will contain the following:
One carpet renovator, with slot J4 iii- by not less than 12
or more than 15 in. long.
One bare floor renovator, 15 in. long, with curved felt-cov-
ered face.
One wall brush, with skirted bristles, 12 in. long and J^ in.
wide.
One hand brush, with hose connection at end, 8 in. long and
2 in. wide.
One 4-in. round brush for relief work.
One upholstery renovator.
One comer cleaner.
One radiator tool.
One curved stem about 5 ft. long.
One straight extension stem 5 ft. long.
At least one hat brush with the system.
58 to 64. Same as for Class 1.
64a. All brushes to be of substantial construction, with best
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224 VACUUM CLEANING SYSTEMS
quality bristles set in close rows and as thick as possible, skirted
with nibber, leather, or chamois skin, so tha/t all air entering
renovator will pass over surface being cleaned.
65 to 68. Same as for Class 1.
69. Hose Racks. Furnish and properly secure in place, where
directed, hose racks in basement, each in first and
second stories ( . . . . racks in all). The racks to be constructed
of cast-iron, galvanized or enamel finish, and each rack to be
suitable for holding 75 ft. of hose of required size.
69a. Hdse. There must be furnished with each hose rack,
75 ft. of non-collapsible hose in three 25-ft. lengths.
70. Hose shall not be less than 1 in. or more than 1^ in. in-
side diameter, best quality rubber hose, reinforced in best man-
ner to absolutely prevent collapse at highest vacuum obtainable
with the exhauster furnished and to prevent collapse if stepped
on. Weight of hose to be not over 12 oz. per linear foot.
71 to 73. Same as for Class 1.
74. On completion of the plant, the pump will be operated
with all outlets closed and under this condition the power con-
sumption must no(t be more than 50% of that required under
test conditions.
75. To test the capacity of plant, one hose line 100 ft. long
shall be attached to iiilet farthest from the separator, with
standard vacometer with 5^-in. opening in end of hose. Hose
lines shall be attached to other outlets, each with 50-ft. hose
and vacometer in end of hose, vacometers having >^-in.
opening and vacometers having ^-in. opening. Under
these conditions 4 in. mercury must be maintained in vacometer
at end of 100 ft. of hose.
75a. Test of Separators, At each of points, near
outlets on different risers selected by the representative,
the contractor shall furnish and spread on the floor, evenly cov-
ering an area of approximately 50 sq. ft. for each outlet, a mix-
ture of 6 lbs. of dry sharp sand that will pass a 50-mesh screen,
3 lbs. of fine wheat flour, and 1 lb. of flnely pulverized charcoal,
if wet separator be used, and 6 lbs. of Portland cement, if bag
be used.
75b. Fifty feet of hose of size required by the system used
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SPECIFICATIONS 225
shall be attached to each of the outlets, and the surface or
surfaces prepared for cleaniijg shall be cleaned simultaneously
by operators provided by the contractor until all of the sand,
flour and charcoal has been taken up, when the exhauster shall
be stopped land the dirt removed from the dry separator and
spread on the floor again, and the operation of cleaning repeated
until the mixture has been handled by the apparatus four
times. If, after thoroughly flushing the system at completion
of the above run, any dust or mud is found in the cylinder,
ports, or valve chambers of the displacement exhauster, or if
less than 95%* of the dirt removed is found in the dry separator
of the centrifugal exhauster, it shall be deemed sufficient ground
for the rejection of the separators. If bag is used, same must
not be disturbed until after capacity test, which will be made
with material in separator after being picked up the fourth
time.
76-77. Same as for Class 1.
78. Evaluation of proposal (for 4-sweeper plant) : No pro-
posal will be considered which contemplates furnishing an ex-
hauster requiring more power to operate under test conditions
than:
Full load, 14 K. W. ; three-quarter load, 12.25 K. W. ; one-
half load, 10.5 K. W.
Test Requirement: Paragraph 75 to be considered full load.
To reduce the load to three-quarters, one ^-in. va(«)meter open-
ing to be closed; to produce one-half load, one j4-in. opening
to be dosed in addition to the J^-in. opening.
Bidders are requested to state in proposal the power con-
sumption required by their apparatus at full, three-quarters
and one-half loads, and in case the guarantees of the various
bidders differ, they will be evaluafted as follows for the purpose
of comparison:
For each full K. W. of power consumption or fractional part
thereof there will be allowed the following amount or propor-
tionate parts for fractional parts of a K. W. hour at the various
loads:
Per Cent, of Full Load. 100 75 50
Amount $156.00 $62.00 $94.00
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226 VACUUM CLEANING SYSTEMS
As an illustration, let it be assumed that proposals have been
received offering equipment in aocordance with specification
requirements, and the one offering the most economical appa-
ratus based on guaranteed power consumption names the highest
price for the installation.
To determine if the purchaser will be justified in accepting
the highest proposal, let it be assumed that he has guaranteed
a power consumption of 1 K. W. less at full load, 0.75 K. W.
less at three-quarters load, and 0.25 K. W. more at half-load
than the lowest bidder. Under these conditions the algebraic
sum of the saving of the higher bidder over the lower bidder
would be 156+46.50—23.50=179, which is the additional
amount in dollars which the purchaser would be warranted in
paying for the apparatus of higher efficiency.
In making the economy test to determine if the guaranteed
power consumption has been fulfilled, an integrating watt
meter, previously calibrated and found correct, will be placed
in circuit and a two-hour run made at each load and the power
consumption based on the meter readings.
Penalty. — It must be distinctly understood to be one of the
conditions under which bids are to be submitted for the work
embraced in this specification that the apparatus shall meet
every requirement of the specification and the guaranty for
efficiency under which conditions the contract price will be paid.
In the event the apparatus tested fails to meet the specified re-
quirements for capacity or economy, or both, the Arohitect shall
have the right to reject the apparatus, absolutely, and reiquire
the installation of satisfactory apparatus, which shall comply
with the contract requirements; or if he elects to accept the
same, in the event the capacity or efficiency at any load (irre-
spective of other loads) is less than that named in the proposal,
then the contract price shall be the amount named in the con-
tract for a satisfactory plant, less the amount of deficiencies
shown by the test based on the following:
For Capacity. — $500.00 for each inch of vacuum and a pro-
portionate part thereof for each fraction of an inch below the
4 in. required in vacometer when operating under full load.
For Economy. — Deduction for each K. W. or a proportion-
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SPECIFICATIONS 227
ate part thereof for each fraction thereof required in excess of
guarantee.
Percentage of Full Load 100 75 50
Penalty $229.00 $93.00 $141.00
This evaluation was based on the same time of operaition and
cost of current as that used in illustration under tests (Chapter
XII).
The yn«.ximum power to be allowed for plants of various
capacities should be as follows :
Capacity in 100%
Sweepers of Load
8 24'
6 20
4 14
2 7.5
In event that the plant is to be run with vacuum **on tap,'*
as in a hotel, a guaranteed power consumption at no load should
be required and evaluated on the number of hours the plant
wiU probably operate under these conditions. This will be the
largest item in the evaluation under such conditions.
75%
50%
of Ixnd
of Load
20
17
18
15
12.25
10.5
6.25
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CHAPTEB XV.
Portable Vacuum Cleaners.
While this book is primarily intended to deal only with
vacuum cleaning systems, which would limit the work to such
apparatus as is permanently installed within the building to be
cleaned, the author considers that it would not be ecMnplete
without some mention of the portable cleaners which are so
popular at the present time.
On first consideration, the portable cleaner would appear to
have a considerable advantage over the stationary type in that
the length of hose is usually limited to not over 15 ft. and
there is no pipe line, which results in the elimination of
practically all friction loss, giving practically the same vacuum
at the renovator as at the exhauster. This should result in a
saving of practically 50% of the jwwer required to operate the
exhauster.
Referring to Chapter XII, we find that the power reqtdred
to operate a really efficient vacuum cleaning system is approxi-
mately 2.5 H. P. per sweeper. If a portable cleaner, with the
«ame efSciency and capacity, be built, it would require at least
V/2 H. P.
Such a cleaner would not be portable in the sense of the
term as applied to the most popular cleaners today. The same,
type has been built on special order by the American Radi-
ator Company, which mounted its 1J4 H. P. Arco Wand machine
on a truck. This cleaner weighs several hundred pounds and
could be moved up and down stairs about as easily as a sewing
machine and would not be of any service in a building not
equipped with elevators. The power required to (^erate this
cleaner is also so great that special power wiring and large
capacity outlet plugs have to be insttalled throughout the build-
ing. Such equipment has been provided in at least two depart-
ment stores where these cleaners are in use. This means that
228
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PORTABLE VACUUM CLEANERS 229
one wires his building for vacuum cleaning instead of piping
it, and there is also the necessity of moving a heavy machine
about to do the same work as a stationary plant.
It would appear to the author that the cost of wiring would
about equal that of piping and that the additional labor re-
quired to move the machine about would cost as much as the
additional power needed by the stationary exhauster.
This cleaner, as well as all other portable cleaners, discharges
the air from the exhauster directly back into the apartment
cleaned, and is open to the same objection that was raised
against the early compressed air cleaners. While all the dust
may be caught by the dust bag, the microbes are allowed to
escape with the air and the cleaner is not a sanitary device
by any manner of means.
There are a few portable machines using rotary exhausters
of the Root type, and piston pumps, all of which are heavy to
move about and, in making them as ligiht as possible, the
efficiency of the exhauster haa been sacrificed. These machines
will do the same quality of cleaning as the stationary plants
recommended for residence work and they require about J4
H. P., which is no less than is needed for a staltionary plant
of the same capacity and efficiency.
The most popular type of portable cleaner is one which can
be attached to a socket or plug connected with the lighting
system. This should limit the power consumption to J^ H. P.
However, many of these cleaners use as much as 400 watts
and a fair average for cleaners retailing at about $125.00 is
250 watts. Such cleaners will exhaust about 25 cu. ft of air
with a vacuum of 1 in. mercury at the vacometer, a 5^-in.
orifice being used. The theoretical power required to move the
air is approximately 50 watts and the overall efficiency of these
cleaners is, therefore, about 20%, as against 40% to 50% in
a good, one-sweeper stationary plant. The power expended in
operating these portable cleaners in proportion to the work
done is no less than with an efficient stationary plant.
Portable cleaners have been made in many types but prac^
tically all the standard makes use one or two forms of vacuum
producers, either the diaphragm pump or the single or multi-
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230 VACUUM CLEANING SYSTEMS
stage fan. The pumps of the f6mier type are able to produce
a vacuum as high as 6 in. to 10 in. of mercury, when no air is
passing, and will displace as high as 30 cu. ft. of free air per
minute, wben operated with a free inlet. They produce about
1 in. of mercury at the carpet renovator when operaited on an
ordinary carpet. When small-sized upholstery renovators are
used, a much higher vacuum is possible. When operated with
bare floor renovators or brushes, the quantity of air exhausted
is not much over 20 cu. ft. per minute and they make very in-
efficient bare floor and wall cleaners, but will do thorough carpet
and upholstery cleaning provided a small enough renovator is
used.
Machines using a multi-stage fan will produce a maximum
vacuum of approximately 2 in. of mercury when exhausting no
air, and will produce a vacuum of approximately 1 in. of mer-
cury when operated on an ordinary carpet. With an unrestricted
inlet, they will exhaust from 40 to 50 cu. ft. of air per minute.
When operoited on a bare floor, they will exhaust approxi-
mately 30 cu. ft. of free air per minute. They are, therefore,
more efficient floor cleaners than the pumps, but cannot do
thorough carpet and upholstery cleaning, no matter how small
the renovator.
The smialler-fan type of machines, in which the fan is placed
integral with the carpet renovator and in which hose is not
used in cleaning floors or carpets, are provided with a single-
stage fan. They produce a suction of not exceeding J^ in. of
mercury when no air is exhausted and will exhaust from 5 to
10 cu. ft. of free air per minute when operated on a carpet.
With a free inlet they will exhaust from 15 to 20 cu. ft. of
free air per minute. These machines are little if any better
than ordinary carpet sweepers.
Machines of this type are open to another objection in that
the dust bag is placed on the outlet of the fan and the dust in
the bag is continually agitated by the passage of the air, with
the result that all the finer particles of the dust are blown
through the bag back into the apartment. To be effective, the
dui^ bag must always be placed on the suction side of the ex-
hauster and should be so arranged that th^ diist will not quickly
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PORTABLE VACUUM CLEANERS 231
cover the entire area of the bag, for, when this occurs, the auc-
tion is quickly reduced to such an extent that no further clean-
ing can be done unltil the bag has been cleaned.
There is another type of mechanical cleaner manufactured
by the Hoover Suction Sweeper Company which is provided
with a mechanically-operated brush for loosening the dirt from
the carpet. The dust is then conveyed through a single-stage
fan to a dust bag. The cleaner does not d^end on the vacuum
to loosen the dirt and will do quite effective carpet cleaning with
a small expenditure of power. Owing to the small suction
produced, it is of little value for cleaning anything but carpets.
From the experience the author has had with portable vacuum
cleaners, some thirty makes having been tested for the Treasury
Department by him and by the Bureau of Standards, the use
of such cleaners is not considered as either an eflScient or sani-
tary means of mechanical cleaning.
If a cleaner requiring small power is required, one of the
smaller stationary plants, costing not over $300.00 and operating
with 5^ or ^ H. P., is considered a better investment than
$125.00 paid for a portable cleaner.
If the purchaser feels that he cannot afford to pay more than
$125.00 for his vacuum cleaner, a type such as the Water Witch
can be furnished for this price. This cleaner is placed in the
basement, with arrangements for starting same from any floor.
The manufacturers state that this apparatus produces a vacuum
of 2 in. mercury in a carpet renovator, 4 in. mercury in an
upholstery renovator and exhausts 25 to 30 cu. ft. of free air
per minute with open hose. The machine operates by water
pressure and the manufacturers state that it requires about 6
to 8 gals, of water per minute. All air is exhausted outside of
the building and all dust washed down the sewer with the ex-
haust water. It is therefore, a fairly efficient and sanitary
cleaning system.
The statements made above apply to parties who own their
residences and occupy offices in modem buildings. There are,
besides these, a great many who live in rented houses and
apartments or occupy offices in buildings where the owners are
not sufficiently progressive to install stationary cleaning plants.
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232 VACUUM CLEANING SYSTEMS
To supply the needs of this class is evidently the field of the
portable cleaner, as even the poorest of these machines is more
effective in the removal of dust and dirt than the broom and
carpet sweeper.
The selection of a portable cleaner by one who must neces
sarily resort to the use of such a cleaner should be made with
care. The motor should be looked into and only one which has
brushes readily removable and one in which the condition of
the brushes can be easily noted should be selected. Lubrication
is important. A good cleaner should be so constructed that it
can be operated for at least 100 hours without relubrication.
The dust bag should always be on the suction side of the
vacuum producer and of such a design and construction that
at least >4 peck of a mixture of 40% sand, 30% flour,
15% sweepings and 15% Portland cement can be picked up
from the floor and retained in the bag and the machine still be
capable of picking up material from a bare floor.
A good test for capacity of a portable machine is to pick up
Yi peck of such material, then fit a thin disk with J^-in.
diameter opening over the end of the hose. A machine, to be
of any value, should show a suction of 3-inrwater and a first-
class machine will show 8 in. under these conditions. This will
do fairly good bare floor work. To ascertain if the machine
will clean carpets, use a similar disk with 5^-in. diameter open-
ing, when a suction of 7 in. water indicates the lowest value
and 16 in. about the best that can be obtained from any port-
able cleaner. Cleaners must be readily portable and should
not weigh exceeding 75 lbs.
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