yi_n_n__rL_n_

REESE LIBRARY

OF THE

UNIVERSITY OF CALIFORNIA

Deceived Accession No. 91390. Class No.

Be sure to get the best, which is fully guaranteed by us, and which always has our trade mark

Established J853

Incorporated J885

CAPITAL, $1,000,000

AD VKKTISEMKN TS

The National Ammonia Go.

GENERAL OFFICES: ST. LOUIS, MO.

EASTERN AND EXPORT OFFICE : 90 WILLIAM ST., NEW YORK

CM. Addres..,] " MANUFACTURERS OF ABSOLUTELY PURE AND DRY

Liquid

Anhydrous

Ammonia

Aqua Ammonia

For Refrigerating and Ice Making Purposes.

Our Ammonia is entirely free from any impurities that

can detract from refrigerating- effects or impair machin- ery, and those using- our products obtain best results with their machines. Our prices are always as low as others for goods of equivalent quality. Inquiries and orders solicited.

UNEXCELLED GOODS. UNEQUALED SERVICE

Our Ammonia can be had of the Following:

NEW YORK— PITTSBURGH—

The De La Vergne Ref. Mach. Co. Union Storage Co., Transfer Agts.

W. M. Schwenker.

NEW ORLEANS—

The National Ammonia Co., L N Brimswi* * m

1OP .IT T)nv:n r»n n *

Theo. J. Goldschmid Co. ™ W' Davis O11 Co-

BALTIMORE-Wm. Mitchell. T MaUinckrodt Chemical Work,

WILMINGTON— Larkin & Scheffer.

Delaware Chemical Co. CHICAGO -

BUFFALO-S. J. Krull. A. Magnus' Sons' Co

BOSTON— Fuller & Fuller Co '

The Lyons & Alexander Co. MILWAUKEE-

KANSAS CITY— S. J. Thomson. Baumbach, Reichel & Co. '

Herman Goepper & Co. •" *J*£ ISMUM— CLEVELAND— Geo. Herrmann Co.

Cleveland Brewers' Supply Co. Pacific Ammonia & Chemical Co.

DETROIT— LIVERPOOL, ENG.

Michigan Ammonia Works. " Ja8- Simpson & Co.

INDIANAPOLIS, IND.— SYDNEY, N. S. W.

Indianapolis Warehouse Co. The Ammonia Co. of Australia.

ADVERTISEMENTS

CROSBY

STEAM GAGE AND VALVE CO.

SOLE MANUFACTURI

CROSBY STEAM ENGINE

AND

AMMONIA INDICATOR

Approved and adopted by the U. S. Govern- ment. It is the standard in nearly all the great Hlectric Light and Power Stations of the United States. It is also the standard in the principal Navies, Government Ship Yards and the most eminent Technical Schools of the world.

When required it js furnished with Sar- gent's Eleetrieal Attachment, by which any number of diagrams from Compound Engines can be taken simultaneously.

This attachment is protected by Letters Patent. The public is warned against other similar attachments which are infringements.

ALSO SOLE MANUFACTURERS OF

Perfect in Design. Faultless in Work- manship.

Crosby Improved Steam Gages, Pop Safety Valves, Water Relief Valves,

Patent Gage Testers, Safe Water Gages, Revolution Counters,

ORIGINAL Single Bell Chime Whistles and other standard

specialties used on Boilers, Engines, Pumps, etc.

MAIN OFFICE AND WORKS: BOSTON, MASS., U. S. A.

Stores: BOSTON, NEW YORK, CHICAGO and LONDON, ENG.

COILS

BENDS AND MANIFOLDS FOB

Ice and Refrigerating Machinery

AMMONIA VALVES AND FITTINGS.

Hairisburo Pipe Bending Go., w.

HARRISBURG, PA.

The Harrisburg Copper Coil Feed Water Heater.

CARBONIC ACID GAS AND ANHYDROUS AMMONIA

RECEIVERS AND CYLINDERS

INDiCATINf

THE

REFRIGERATING MACHINE

HE APPLICATION Of Tr, •O»"TO THE AMMONIA

COMPRESSOR AND STEAM KNt.iJftt, WITH PRACTICAL

INSTRUCTIONS RELATING TO THE CONSTRUCTION

AND USE OF THE INDICATOR AND READING

AND COMPUTING INDICATOR CARDS

GARDNER T. VOORHEKS, S. B.

MECHANICAL ENGINEKR WITH THE x

gUINCY MARKET COLD STORAGE CO. ,| BOSTON, MASS.

CHICAGO

H. S, RICH A;

INDICATING

TtiE

REFRIGERATING MACHINE

THE APPLICATION OF THE INDICATOR TO THE AMMONIA

COMPRESSOR AND STEAM ENGINE, WITH PRACTICAL

INSTRUCTIONS RELATING TO THE CONSTRUCTION

AND USE OF THE INDICATOR AND READING

AND COMPUTING INDICATOR CARDS

BY

GARDNER T. VOORHEES, S. B.

MECHANICAL ENGINEER WITH THE

QUINCY MARKET COLD STORAGE CO.

BOSTON, MASS.

CHICAGO

H. S. RICH & Co.

Copyrighted 1898, by H. S. RICH & CO.

ALL RIGHTS RESERVED.

Press of ICH AND REFRIGERATION,

CHICAGO.

PREFACE.

Often while plotting- the adiabatic curve on an indicator card taken from an ammonia com- pressor, I have wished to shorten the time re- quired and simplify the process. This led to working- out the constants in Table No. 1. Having- these constants, Table No. 2 naturally sug-g-ested itself to still further simplify the work. In addi- tion to this I have added such other matter as seemed pertinent to a work of this character, hoping- to place before the reader all necessary references for one who may have to work up indicator cards taken from an ammonia com- pressor. If my reader appreciates the value of the adiabatic curve after looking- throug-h this work, and learns to use Table No. 2, I feel that my aim will have hit the mark.

G. T. V.

91390

CONTENTS.

PART I.

INDICATING THE AMMONIA COMPRESSOR.

Chapter I.— The Elementary Indicator; a simple

description of the principles involved 7 Chapter II. — The Value of Indicating- a Compressor 11

Chapter III.— The Adiabatic Curve 19

Chapter IV.— The Isothermal Curve 25

Chapter V. — Discussion of the Adiabatic and Iso- thermal Curves 29

Chapter VI. — Finding the Horse Power of an Indi- cator Card 37

Chapter VII. — Actual Displacement of a Compressor 39 Chapter VIII.— Special Faults as Shown by Cards. . . 4<i Chapter IX. — Wet Compressor System Indicating-. . 51 Chapter X. — Instructions for Connecting- Indicator

to Machine.. . 57

Chapter Chapter

Chapter Chapter Chapter Chapter Chapter

PART II.

INDICATING THE STEAM ENGINE.

I. — The Steam Engine Indicator 59

II.— How and Where to Attach the Indi- cator 72

III.— The Drum Motion

IV. — How to Take Diagrams

V. — How to Find the Power of an Engine.

VI.— The Hyperbolic Curve

VII.— Amsler's Polar Planimeter. . ,

76

84

89

96

103

Chapter Chapter

PART III.

CONSTRUCTION OF INDICATORS.

I.— The Crosby Indicator 108

II.— The Bachelder Adjustable Spring

Indicator.., ..116

CONTENTS. V

Chapter III. — Improved Robertson-Thompson Indi- cator 119

Chapter IV.— The Buffalo Indicator. 123

Chapter V. — American Thompson. Indicator 126

Chapter VI.— The Tabor Indicator 133

Chapter VII. — The Improved Victor Reducing Wheel. 141

Chapter VIII.— The Ideal Reducing- Wheel .144

Chapter IX. — Sargent's Electrical Attachment for

Steam Engine Indicators 146

Chapter X. — Armsler's Polar Planimeter 149

Chapter XI.— The Lippincott Planimeter 150

Chapter XII.— The Coffin Averaging Instrument 154

PART IV.

MISCELLANEOUS TABLES.

Properties of Saturated Ammonia 160-163

Table of Ammonia Gas (Super-heated Vapor) 164

Refrigerating Effect of One Cubic Foot of Ammonia

Gas 165

Number of Cubic Feet of Gas Pumped per Minute to

Ton of Refrigeration 165

Anhydrous Ammonia, Composition of 166

Testing Anhydrous Ammonia 166-167

Comparisons of Thermometer Scales 168

Mean Pressure of Diagram of Ammonia Compressor . 169

Properties of Saturated Steam , 170-172

Mean Effective Pressure of Diagram of Steam Cyl- inder 173

Head of Water and Equivalent Pressure in Pounds

per Square Inch 174

Properties of Solution of Salt (Chloride of Sodium). . .175

Properties of Solution of Chloride of Calcium 175

Diameters, Areas and Circumferences of Circles. .176-178 Table of Piston Speeds : Feet per Minute 179

INDICATING

THE

REFRIGERATING MACHINE

PART I. INDICATING THE AMMONIA COMPRESSOR.

CHAPTER I.

THE ELEMENTARY INDICATOR.

For the convenience of those who are not familiar with the principle of the indicator, but may wish to look through this book, I will give an elementary description of the principles in- volved. I sincerely hope that thus I may be able to bring- this work understandingly before those who are interested in or own compressors, but who have not had a technical education.

In Fig. Itf, shown on opposite page, let A be the compressor cylinder; B the piston; C the suction valve; D the discharge valve; E the piston rod; F the cross-head; G G cross-head guides; If a. board made fast to the cross-head; /a piece of paper called an indicator card blank, which is tacked to board H; /a small cylinder, having piston A" and piston rod Z, compression spring M; Arpencil carried by piston rod L; O O pipe leading from cylinder A to cylinder J; P cock that may connect cylinders A and/, or shut off A from / at the same time leaving cylinder/ open to the atmospheric pressure.

8 INDICATING THE

Now we will suppose pencil Arto press against paper /, and cross-head f^to move in the direc- tion 1, 2. Evidently the pencil N will trace the straight line aa^ on paper /. Now whatever pressure exists in cylinder A must also be in cylinder J, being transmitted through the pipe O O. Suppose now the pencil N at position c representing atmospheric pressure in cylinder A, then allow pressure in cylinder A to gradually increase, the cross-head F remaining fixed in position. It is evident that this pressure will move piston K, compress spring J/and trace the line cb with pencil N. Then if the pressure in cylinder A is reduced the piston It will return to its original position by virtue of spring M. Now suppose spring Mto be so constructed that one pound per square inch pressure in cylinder A will compress it .01 of an inch and that 100 pounds per square inch will compress it one inch; it will be evident that every .01 of an inch of line a b represents one pound per square inch press- ure in cylinder A. If a b is .75 inches long, then the pressure in cylinder A is seventy-five pounds.

If cock P is so turned as to open cylinder/ to the air, when the cross-head F moves, it will cause pencil N to trace line c c^ , called the atmos- pheric line. All vertical distances above this line will represent pressures above the atmos- phere. All vertical distances below this line will represent pressures below the atmosphere. The pressure of the atmosphere is 14.7 pounds per square inch. Should a perfect vacuum be found in cylinder A, then pencil N would go to #!,#! representing to scale, by its vertical dis-

AMMONIA COMPRESSOR. H

tances from line c c\ , 14.7 pounds per square inch pressure. Now it should be clear that any varia- tion of pressure in cylinder A will either raise or lower pencil N in" relation to line c cl , and that any motion of the cross-head F will move the paper so that the pencil A^will vary its horizontal dis- tance from line bb^. As the cross-head Amoves with the same motion as that of piston B it is evident that all points at a horizontal distance from line b b1 represent different positions of pis- ton B, and all vertical distances from line ccl represent pressures in cylinder A on piston B at these positions.

Now let us see how the indicator pencil will act under an actual test. Let us suppose that piston B has just started in the direction of the full arrow. Then pencil N at point a shows the beginning- of piston's stroke and pressure, ca, which is the back pressure (gauge). As the piston B moves forward the gas flows into cyl- inder A through suction valve C at the con- stant back pressure from the expansion cham- ber through pipe R, and the pencil traces the line a ai.

Now the piston B having reached the end of its stroke, B^ starts back in the direction of the dotted arrow. In doing this it begins to. compress the gas in the cylinder ^4, thus clos- ing suction valve C; and as the pressure in cyl- inder A becomes more and more, the pencil traces the curved line a± d (the compression,, curve). When the piston reaches the position, Z?2» corresponding with the pencil point d, the. pressure in cylinder A is a little greater than that transmitted by pipe Q from condenser to

(2)

10 INDICATING THK

the discharge valve D. From this position the piston discharges the gas past the discharge valve to the end of the stroke, the pencil in the meanwhile tracing the wavy, peaked line, db. The reason for the unevenness of this line is the chattering of the discharge valve D. The piston B now having reached its original position, starts to go back in the other direction (that of the full arrow) again. Now the dis- charge valve D closes, due to the condenser pressure, and the pressure in cylinder A falls to that due to the suction or back pressure. As this change takes place while the piston^ is changing its motion from forward to backward, the cross- head moves only a very small amount, and a nearly vertical line, b a, is traced by the pencil N.

We have now followed the pencil through rts travels, and the resulting diagram, aaldb a, is the desired indicator diagram. This same explanation can apply to a steam card by going around the diagram the other way; bdal ab will be a steam engine card, except that the line bd will be more smooth, the line da^ will represent the expansion line, d the point of cut-off, and a1 a the exhaust line. The practical forms of indi- cators, such as are used to-day, do not differ in principle from this elementary form; they differ only in detail. The card / is carried on an oscillating drum, which is oscillated by a cord from the cross-head. The pencil is carried by a straight line multiplying device. Another chap- ter gives full description of the various standard makes of indicators, so I will not go farther into the subject of the construction of the indicator at this point.

AMMONIA COMPRESSOR. 11

CHAPTER II.

THE VALUE OF INDICATING A COMPRESSOR.

In this chapter I will try to demonstrate the value of indicating" an ammonia compressor, of doing- it regularly, and knowing- how to correctly interpret the meaning- of the indicator card. I have known men who were well up on indicator practice, and who are intellig-ent engineers, to let a compressor run for months, when a very little knowledg-e of such methods as I hope to set forth would have saved a great amount of worry in regard to the quality of work being- done, and a good many hundred dollars of expense on coal bills.

All competent engineers know the names of the various lines and are familiar with the gen- eral appearance of the indicator card. They know that the admission line is parallel to the atmospheric line. The compression line rises in an easy curve to the discharg-e line. The discharge line is usually wavy or peaked, due to the vibration of the discharge valves. The ad- mission and discharge lines should be joined by a nearly vertical line. The card should have a square heel. We know that this square heel in- dicates the amount of clearance.

In Fig. 1 the card has a square heel at «, con- sequently you say, " The clearance is small." If the card had been like Fig. 2, you would say, u Very bad; too much clearance," and you would overhaul your compressor and make the clear- ance what it should be. How many engineers

12

INDICATING THK

AMMONIA COMPRESSOR.

13

14

INDICATING THE

AMMONIA COMPRESSOR. 15

go any farther than this? They take a card like Fig-. 1, look at it, see that it has a good square heel, and say, u This is a good card." As a re- sult they g-o back to their other duties, thinking that their compressor is doing- g-ood work. Here is where many a good man makes a mistake. He has done what he could, but for lack of a practical way of applying thermodynamic reason- ing to his card he can go no farther.

I am acquainted with an engineer who knows a great deal about running a compression plant. One day he handed me a card like Fig. 3. He said, "Here is a good card." I took the card, applied the simple rules to it, that I am about to give, and found that the compressor was in a very bad way. I doubt if there is an engineer who can look at the card as given in Fig. 3, and say it is a good or a bad card. It is impossible to tell whether the compression line is good or bad by a simple inspection. One may notice if the com- pression line is very bad. Even then I think there would not be one man in a great many that could pass a valuable opinion on it.

What the engineer needs is a guide, some- thing to compare his card with; something that he knows is all right. In a picture or diagram the way of comparing size and proportion is by having some familiar object, as a man, for com- parison. You may know then that the bridge you are looking at is large or small, that you are looking at the picture of a great cathedral or a small church. In much the same way it is necessary to have your comparison on an indi- cator card.

This comparison or guide is the adiabatic

16

INDICATING THI<;

AMMONIA COMPRESSOR. 17

line. The isothermal line is interesting-, and also serves as a guide, but it is a poor guide. One cannot draw sound conclusions in all cases from the isothermal line's relation to the com- pression curve, as traced by the indicator pencil. The adiabatic line is the true guide. The cal- culation of this adiabatic line necessitates the use of logarithms in calculating the fractional powers of numbers. This may be difficult for some engineers to do. Even our best engineers will find that it is no small matter to figure the adiabatic line for an indicator card. They can do it easily enough, no doubt, but it will take much more valuable time than they usually have to devote to it. Consequently, I believe that if I set forth a simple and practical way of obtaining this line, engineers will, by using this method, be able to get much better work out of their machines. The owners of plants will also save money that is needlessly wasted at present.

I reproduce Fig. 3 here in Fig. 4, having drawn the adiabatic line a a on the card. This card, that looked so good to my friend the engi- neer, is now shown to be very bad. I told him that probably the cylinder gasket between the discharge port and the cylinder was blown out. (The reasoning for this will be given later.) Upon an examination of the compressor this was found to be the case. The machine, I am sorry to say, had been running for a long time in this condition. Being a large machine, it had need- lessly wasted a good deal of money while thus running.

18

INDICATING THE

AMMONIA COMPRESSOR 19

CHAPTER III.

THE ADIABATIC CURVK.

An adiabatic line is a curve that represents the adiabatic expansion or compression of a gas or vapor. Adiabatic expansion or compression is the expansion or compression of a gas or vapor, without loss or gain of heat. It is

Op Op

expressed by pv^'^=pl'vl^ where p = initial pressure, v= initial volume, p^ = final pressure, 27 ! = final volume, £p= specific heat at constant pressure, £v = specific heat at constant volume. cj- is called the ratio of specific heats; for am- monia gas it is .3^°^ = 1.3 .*. p v1-'3 =plvl*-*. That is, the initial pressure times the 1.3 power of the initial volume is equal to the final press- ure times the 1.3 power of the final volume, p and^j being absolute pressures.

In Fig. 5 the atmospheric line A A is the line drawn by the indicator pencil when the indicator cock is so turned that the atmospheric pressure is on both sides of the indicator piston. Meas- ure off perpendicular to and below A A the dis- tance a b, equal to the atmospheric press- ure, 14.7 pounds, using the same scale as that of the indicator spring. Draw a line through b parallel to A A. This line is the vacuum line V V. Draw lines Z?..Z?and C C, perpendicular to the atmospheric line A A, and tangent to or touching the extreme right and left hand por- tions of the diagram. I disregard the clearance, as being too small to appreciably affect the re- sults to be obtained. All pressures must be

20 INDICATING THE

measured at right angles from the vacuum line VV. The pressures are then the true or abso- lute pressures.

Now divide line V V into ten equal parts. The point where the right hand end of the dia- gram cuts the line C C at c is the point of the beginning of the compression. The vertical distance from c to V V is the absolute back pressure when measured on the same scale as that of the indicator spring.

Let p= the absolute back pressure, as measured from the vacuum line V V to c. At the beginning of the compression, as the cylin- der is full of gas, z' can be called 1. The most convenient point from which to draw the adia- batic line will be from the point of the begin- ning of compression, or where v=l. Now as I1-3 = 1, we have /X 1 =/, z^1 3 or p^ = ^3. pi is the ordinate (or vertical distance from VV) of any point, F,, on the adiabatic line for a corresponding abscissa (or horizontal distance on V Ffrom C C1), p being the absolute back pressure under consideration, and z1, varying from 1 to 0.

The divisions of V V are now marked, as shown on Fig. 5, viz.: .9, .8, .7, .6, .5, .4, .3, .2, .1 and 0. These points on V V indicating that the volume at these points is either .9, .8, .7 to .1 or 0, as the case may be.

.I1<3=the number which=l. 3 X logarithm of .1. Log". .1=9.000000—10

1.3 multiply by 1.3 11.700000—13

—3 +3 add and subtract 3

8.700000— 10=lojr. of .05 .-. .OS=.l1'3

AMMONIA COMPRESSOR. 21

Log". .2=9.301030—10

1.3 multiply by 1.3 27903090 9301030

12.0913390—13

—3 _ -j-3 add and subtract 3 9.0913390— 10=log- of .123 .-. .123=.2I<8

In like manner:

TABLE No. 1. .I1'3 =3.050 .2l'3=.123 .31's=.209 .41-3=.304 .5'-s=.406

Now, having- the values of .I1 3 to.91 3 we can find values for p .^ p .%•> p .% to^.9, by substituting the corresponding- values of v^ , v ,2 to v,9 in for-

P

t-»=^

p-= -£*

P 6=: ~5v^

As = -=- T7

A3=-^4

A.= li #

22

INDICATING THE

TABLE NO. 2.

ADIABATIC CONSTANTS.

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197.3

P. 3

263.0

267.8

272.4

277.2

282.0

287.0

P. 2

447.0

466.0

461.0

472.0

480.0

487.0

P-.

1100.0

1120.0

1140.01160.0

1180.0

1200.0

AMMONIA COMPRKSSOK. 23

If now we give a value of 15 to p= fifteen pounds absolute back pressure, and substitute for z>.91>3 to z*.!1'3 their values as given in table No. 1 we will have :

A« = .B\\ = 17-2 A« = .^A= 20.0

A7 = .tf* = 24.9 Ae = .rfft = 29.2 As = . I'D8* = 37.0 A. = .#* = 49-3 As ^ .i1o59 - 71.7 A. = . to =122.0 A i = -o^o =300.0

In like manner/. 9 to/., can be found for any other value of/. These values have been calcu- lated and are given in Table No. 2, up to p=60 pounds, advancing- by increments of one pound.

To plot the adiabatic line by means of Table No. 2: Find in the horizontal line with p the number corresponding- to the absolute back pressure on your card. Then in the same verti- cal column that contains your absolute back pressure, and opposite/. 9 find the value of /.9. Lay this off on line .9 (Fig-. 5) from VVto the same scale as that of your indicator spring-. Do the same for /.8 /.7 to /.,. You then have a series of points throug-h which you draw the smooth curve c^ c (Fig-. 5). This line £, c is the adiabatic line.

If the ammonia gas were compressed from point c (Fig-. 9) up to the condenser pressure in a perfectly tig-ht and non-conducting cyl- inder without loss or gain of heat, then the adiabatic line would be the curve traced by the indicator pencil. Now if there is no leakag-e past the valves or piston, this adiabatic line will

24 INDICATING THK

in all ammonia compressors, as used to-day, almost overlie the compression line of the card for its whole length (see Fig-. 9).

The water jacket does not seem to affect the compression line to any great extent. The jacket of water may affect the relative positions of the adiabatic and compression curves, during the latter one-fourth or one fifth of the stroke (when the gas is very hot); then the adiabatic line will be seen to be slightly above the com- pression line (see Fig-. 9). If the compression line of the card does not follow very nearly the adia- batic you can make up your mind that something' is wrong in connection with the piston, valves or gaskets of the compressor. This is, of course, as- suming that the indicator is properly connected; that the pipe leading from the cylinder to the in- dicator is short and of small bore, say >^-inch diameter, and that this pipe is well insulated from the cooling effect of water in the jacket. One thing is certain, the compression curve can never lie above the adiabatic line if the compressor is working properly. I will take up and discuss the conclusions that can be drawn from the dif- ferent relations of the adiabatic and compression lines as soon as I have indicated how to draw the isothermal line on the indicator card.

AMMONIA COMPRESSOR.

CHAPTER IV.

THE ISOTHERMAL CURVE.

If there is no leakage to or from the cylinder during- compression, and if the cylinder walls, head and piston are perfect conductors of heat, surrounded by a suitable cooling- medium, then the temperature of the g-as will remain constant during- its compression, and we will have the iso- thermal line traced by the indicator pencil. No ammonia compressor is running- to-day that will give a compression line like this on the indicator card. I doubt very much if an ammonia com- pressor will ever be built that will give a card where the compression line will approach it in any great degree. There is such a great amount of heat generated during compression that about all that can be hoped for is to prevent too great an accumulation of heat in the metals of the cylinder. This is all that I believe is accomplished by the water jacket, even in the best compressors built.

The isothermal line is more easily calculated than the adiabatic. It is represented by the formula ^^=^2^. That is, the initial pressure times the initial volume is equal to the final pressure times the final volume. Takings as 1,

then pXl=-fi\xVi orPi=^-> Now take values of z>j from .9 to .1 as we did in the case of the adiabatic line; then as p represents the back pressure in pounds absolute, the different values of p^ as f,9 p.% p^ to^.t, will be found by dividing the absolute back pressure p by the

(3)

26

INDICATING THE

TABLE NO. 3.

ISOTHERMAL CONSTANTS.

p.

15

16

17

18

19

20

£1

££

£3

«4

P. 9

16.7

17.8

18.9

20.0

21.1

22.2

23.3

24.5

25.6

26.7

P. 8

18.7

20.0

21.2

22.5

23.7

25.0

26.2

27.5

28.7

30.0

P.7

21.4

22.8

24.3

25.7

27.1

28.6

30.0

31.4

32.8

34.3

P.6

25.0

26.7

27.3

30.0

31.7

33.4

35.0

36.7

38.4

40.0

P.B

30.0

32.0

34.0

36.0

38.0

40.0

42.0

44.0

46.0

48.0

P. 4

37.5

40.0

42.5

45.0

47.5

50.0

52.5

55.0

57.5

60.0

P. 3

50.1

53.4

56.7

60.1

63.4

66.7

70.1

73.4

76.7

80.1

P 9

75.0

80.0

85.0

90.0

95.0

100.0

105.0

110.0

115.0

120.0

XT • 2

P.I

150.0

160.0

170.0

180.0

190.0|200.0

210.0

220.0

230.0

•240.0

P*

«5

«6

«7

«8

£9

3O

31

338

33

34

P-9

27.8

28.9

30.0

31.1

32.2

33.3

34.4

35.6

36.7

37.8

P. 8

31.2

32.5

33.7

35.0

36.2

37.5

38.7

40.0

41.2

42.5

P. 7

35.7

37.1

38.6

40.0

41.4

42.8

44.3

45.7

47.2

48.6

P. 6

41.7

43.4

45.0

46.7

48.3

50.0

51.7

53.4

55.0

56.7

P. 5

50.0

52.0

54.0

56.0

58.0

60.0

62.0

64.0

66.0

68.0

P. 4

62.5

65.0

67.5

70.0

72.5

75.0

77.5

80.0

82.5

85.0

P. 3

83.4

86.7

90.1

93.4

96.7

100.1

103.4

106.7

110.1

113.4

P. 2

125.0

130.0

135.0

140.0

145.0

150.0

155.0

160.0

165.0

170.0

P.1

250.0

260.0

270.0

280.0

290.0

300.0

310.0

320.0

330.0

340.0

p

35

36

87

3$

39

4O

41

42

43 44

P-9

38.9

40.0

41.2

42.3

43.4

44.5

45.6

46.7

47.8

48.9

P'8

43.7

45.0

46.2

47.5

48.7

50.0

51.2

52.5

53.7

55.0

P. 7

50.0

51.4

52.8

54.3

55.7

57.2

58.6

60.0

61.4

62.8

P. 6

58.4

60.0

61.7

63.4

65.0

66.7

68.4

70.0

71.7

73.4

P- 5

70.0

72.0

74.0

76.0

78.0

80.0

82.0

84.0

86.0

88.0

P-4

87.5

90.0

92.5

95.0

97.5

100.0

102.5

105.0

107.5

110.0

P.3

116.7

120.1

123.4

126.7

130.1

133.4

136.7

140.1

143.4146.7

P. 2

175.0

180.0

185.0

190.0

195.0

200.0

205.0

210.0

215.0j220.0

P.I

350.0

360.0

370.0

380.0

390.0

400.0

410.0

420.0

430.0|440.0

p.

45

46

47

48

49

50

51

52

53

54

P-9

50.0

51.2

52.3

53.4

54.5

55.6

56.7

57.8

58.9

60.0

P-8

56.2

57.5

58.7

60 0

61.2

62.5

63.7

65.0

66.2

67.5

P-7

64.3

65.7

67.2

68.5

70.0

71.4

72.8

74.3

75.7

77.2

P. 6

75.0

76.7

78.4

80.0

81.7

83.4

85.0

86.7

88.4

90.0

P. 5

90.0

92.0

94.0

96.0

98.0

100.0

102.0

104.0

106.0

108.0

P, 4

112 5

115.0

117.5

120.0

122.5

125.0

127.5

130.0

132.5

135.0

P.3

150.0153.4

156.7

160.0

163.4

166.7

170.0

173.4

176.7

180.0

p]2

225.0230.0

235.0

240.0

245.0

250.0

255.0

260.0

265.0

270.0

P.'t

450.0|460.0

470.0

480.0

490.0

500.0

510.0

520.0

530.0|540.0

p.

55

56

57

58

59

60

P-9

61.2

62.3

63.4

64.5

65.6

66.7

P-8

68.7

70.0

71.2

72.5

73.7

75.0

P-7

78.5

80.0

81.4

82.8

84.3

85.7

P- 6

91.7

93.4

95.0

96.7

98.4

100.0

P. 5

110.0

112.0

114.0

116.0

118.0

120.0

P-4

137.5

140.0

142.5

145.0

147.5

150.0

P.3

183.4

186.7

190.1

193.4

196.7

200.1

P. 2

275.0

280.0

285.0

290.0

295.0

300.0

P.I

550.0

560.0

570.0

580.0

590.0

600.0

AMMONIA COMPRESSOR.

27

volume z;.9, z>.8 tox^. Let^>— 15 pounds abso- lute; then

/.9= |= 16.7

P.B- 15»= 18.7

A7= f— 21.4

Ae- i- 25.0

As= 1= 30.0

/>.4= \= 37.5

/.a= 1= 50.1

AS- 1= 75.0

/.!= if =150.0

In like manner ^.9 to^.t can be found for any other value of p. These values have been cal- culated, and are given in Table No. 3, up to sixty pounds.

To plot the isothermal line by means of Table No. 3, proceed the same as explained in regard to the adiabatic line. Fig". 6 shows a card upon which this has been done.

28

INDICATING THE

AMMONIA COMPRESSOR. 29

CHAPTER V.

DISCUSSION OF THE ADIABATIC AND ISOTHERMAL CURVES.

Now, let us discuss the conclusions that may be drawn by inspecting- a card having- these adiabatic and isothermal lines drawn on it. First, let us discuss the adiabatic line. Take the card shown by Fig-. 7. Here is seen that the compression line is above the adiabatic line. Something- is wrong-; what is it? Let us consider what conditions could exist that would cause this condition of affairs. It is evident that the press- ure in the cylinder increases faster than could be caused by the action of the piston. The same conditions that cause the compression line to lie above the adiabatic line during- compression will cause the cylinder to be cheated out of part of its full charg-e of g-as from the suction pipe. The reason is that the hig-h pressure gas from the condenser is leaking- into the cylinder, either through leaky discharge valves, their gaskets or the cylinder head gasket be- tween the cylinder and the discharge port. Therefore, we pump much less gas than we should. It also takes more power to run the compressor, as will be evident from the in- creased area of the diagram. It will not take long for a compressor to waste enough coal to buy a first-class indicator, if this condition of affairs is allowed to go on for any great length of time.

In large machines the loss will be very great.

30

INDICATING THE

AMMONIA COMPRESSOR. 31

The engineer should take off the cylinder head and examine the cylinder head gasket. If it looks bad, replace it with a new one. Try the valves with the fingers, and see that no scale or foreign matter has attached itself to the valve or its seat. Also examine the valve cage gas- kets. After having done all that you can to remedy the trouble, by a careful examination, replace the cylinder head, and connect a press- ure gauge to the indicator connection. Allow the condenser pressure to act upon the outer faces of the discharge valves. If the pressure, as shown by the gauge, remains the same or in- creases very slowly you have remedied the difficulty. Otherwise, if the pressure increase rapidly, you have not.

In nine cases out of ten the engineer will find upon his first careful examination of the gaskets and valves that the gasket is defective, or that there is some foreign substance in the valve seat. It may be that the valves need regrinding. This is a point that is rather difficult to deter- mine by a mere inspection, hence the pressure gauge test.

Now let us examine the card as shown by Fig. 8. Here the compression line is some little dis- tance below the adiabatic line ec. It approaches the isothermal line dc. Some engineers might thoughtlessly say: "What a fine card! how effi- cient the water jacket must be!" etc. But, as I said before, compressors "are not built that way." By apparently being so good the card gives ample evidence of a very bad state of affairs within the compressor.

Let us see what conditions could give this

32

INDICATING THK

AMMONIA COMPRESSOR. 33

result. It is evident that the pressure is not as great at any point on the curve as it should be. What is the cause of this? Some of the gas has leaked out of the cylinder, either by leaky suc- tion valves or their gaskets. The cylinder head gasket may be defective between the suction port and the cylinder, or you may have a leaky piston. It is evident that a sort of rubber ball action is going on in the cylinder. Part of the gas is compressed and expanded between the suction pipe and the cylinder, in place of being discharged into the condenser. The gas is in part pumped over and over again, thereby cut- ting down the capacity of the machine. Remove the cylinder head, examine the gaskets and valves. Do all that you can by a careful inspec- tion to make good the trouble. Then replace the cylinder head and connect a pressure gauge to the indicator connection. Compress the gas in the cylinder so as to have a high pressure. Note the pressureon the gauge. If it does not decrease, or if it decreases very slowly, you have remedied the trouble. If it decreases rapidly, either the valves need regrinding, the piston needs new rings or the cylinder should be rebored, or all these troubles may exist at once. After having had the valves reground if the pressure test, as indicated above, still shows a rapidly decreasing pressure, you would better call in the agent for your machine, and let him decide whether the piston rings or the boring of the cylinder are at fault.

Fig. 9 shows the relations of the compression curve and adiabatic line, e c, that your compressor should give if in perfect condition. It has prob-

34

INDICATING THK

AMMONIA COMPRESSOR. 35

ably occurred to you while reading- the above that you might do all of your testing- with a pressure gauge, in place of bothering- with an indicator. This is true, in a way. Engineers who do not own an indicator may make all the above tests in regard to leaky valves, etc., by connecting a pressure gauge to the indicator cock and pro- ceeding as explained above.

The indicator card is a valuable permanent record of what your compressor is doing. It should be taken every week, dated and filed away for future reference. A steel indicator is pre- ferred for ammonia work. However, you may use your composition indicator without fear of damage if you keep it well oiled, and thoroughly clean it as soon as you have finished your test.

36

INDICATING THE

AMMONIA COMPRESSOR. 37

CHAPTER VI.

FINDING THE HORSE POWER OF AN INDICATOR CARD.

To obtain the horse power, or work of com- pression, represented by the indicator card it is convenient to have a planimeter, and thus meas- ure the area of the card. Then divide the area thus found by the length of the card in inches, and multiply the result by the scale of the spring- used. The result is the mean effective pressure, expressed as M. E. P. The mean effective press- ure is the average pressure of the gas in the cylinder from the beginning of suction to the end of discharge.

I will not go into the method of using the planimeter, as it is fully explained in the instruc- tions that are furnished with each instrument, and also in Parts II and III of this book. If you are not fortunate enough to own a planimeter, and cannot borrow one, you can obtain the M. E. P. as follows : In Fig. 10 you should already have your card divided into ten equal spaces, vl z'.9, z>.8 z/.7, etc. All that is necessary is to find the average heights of these areas that are included between the vertical lines as ^.9^.8 and the ad- mission and compression or discharge lines. Divide each of these spaces, v^v,9 toz'.jZ',,, into two equal parts, and draw through these divis- ions the dotted lines as shown, which are num- bered 1, 2 to 10.

Measure the length of each line from the admission line to where it cuts the compression or discharge curve, using the same scale as that

38 INDICATING THE

of the indicator spring- used. Add tog-ether these leng-ths and divide the result by 10. The quo- tient is then the average height or the M.E.P. Having the M. E.P., the horse power is readily

found by the following simple formula:

_ nXlXaX (M.E.P.) ' ' 7 33,000

Where 72— strokes (not revolutions) per minute. /=length of stroke in feet. tf=area of piston in square inches. M. E.P.=mean effective pressure.

Every engineer should know the constant for his compressor.

It is evident that in the above formula

33,000

is constant for all conditions or tests. This value, 33 ooo * *s ^e cons^an^ for your compressor, and is indicated by C. Therefore the horse power is

H. P.= CX n X (M. E. P.)

The horse power of the steam engine is obtained in the same way. Only remember that whereas your compressor may have been single- acting, as is assumed for the above formula, your engine is double-acting; therefore you should multiply your strokes by 2, and your engine con_ stant is approximately 33 ^ This is also the constant for a double-acting compressor. In a double-acting compressor or a steam engine the area of one side of the piston must have de- ducted from it the area of the piston rod, thus giving the effective area of the piston. The true constant for that side of the piston will then be ~~33 000 * ai bein§" the area of the piston rod in square inches, The difference between the H. P. of the steam engine and that of the compressor is the friction of the machine.

AMMONIA COMPRESSOR. 39

CHAPTER VII.

ACTUAL DISPLACEMENT OF A COMPRESSOR.

The actual displacement of the compressor should be known. We know that the compressor does not pump the weight of gas that it should, as figured from its theoretical displacement, the reason being, as stated by Prof. Deiiton, that the gas is rarefied during suction by coming in contact with the hot walls of the cylinder.

It is evident that if the gas is rarefied the weight of a given volume of gas would be less after rarefaction than before. Consequently our compressor may vary in its actual capacity from 70 per cent to 90 per cent of the theoretical capacity, these two figures, 70 per cent and 90 per cent, being extreme cases that are rarely if ever reached. The common value of the actual capacity is from 75 per cent to 80 per cent of the theoretical capacity.

My theory in regard to this rarefaction is that as the gas enters the cylinder through the narrow annular openings between the hot valves and their seats, it is superheated and thus rare- fied. There is only a brief interval between the end of compression and the beginning of suction. When suction begins the cylinder head and valves are at their maximum temperature. Consequently I could think of no better way of heating a gas than that of forcing it through these narrow an- nular openings, having hot metal surfaces to pass by. The head and valves should be cooled by some means other than the gas to be pumped.

40 INDICATING THK

The gas should arrive at the cylinder as near the temperature of the boiling- point of the liquid ammonia, due to its back pressure, as possible. Every degree of superheating- cuts down the actual capacity of the compressor. It is well known that a gas will expand T J-T of its volume at 0° F. for every degree of increase of its temperature. The suction pipe to a com- pressor should be thoroughly insulated. The vapor from the expansion coils should not be used for any cooling purpose whatsoever. Cool- ing the liquid ammonia by means of the return vapor is poor practice. To be sure, it is an advantage to have the ammonia arrive at the ex- pansion valve as cold as possible, but it is more disadvantageous to warm up the vapor than not to cool down the liquid with it.

It will be evident how poor the gas is in cool- ing power when it is remembered that one pound of vapor only has a cooling effect of .5 British thermal units for every degree F. that it warms up; while a pound of the liquid ammonia has while vaporizing a cooling effect of 555 B. T. U., on an average, or over one thousand times as much. (Cool the liquid ammonia by any other available means, but not by the return ammonia vapor.)

If the expansion coils or receptacle are prac- tically built, if the coils are not too long, you will have no trouble with liquid ammonia coming over to your machine. Should you be unfortunate enough to have a brine tank or expansion coils that will squirt the liquid in the form of a spray over to the compressor, you would better put a separator in your suction pipe or else get a more efficient brine tank or expansion coils.

fi UNIVERSITY J

AMMONIA COMPRESSOR?**"11""' 1^*^41

The talk about where the frost line should or should not stop on the suction pipe is all bosh. The frost should go right up to and around the compressor cylinder if it is uninsulated. But better still, the suction pipe and the cylinder should be thoroughly insulated from the effect of heat from outside sources. It is necessary to know the temperature of the boiling point of the ammonia in your expansion coils, and also the temperature of the gas at the suction entrance to your compressor. So long as the tem- perature of the gas at the compressor is 5° or 10° F. above that of the boiling ammonia, there will be no danger of getting liquid over to your machine.

I would not let the gas get colder than 10° above that of the boiling point of the ammonia. Probably there are hundreds of plants that can- not follow this advice because they have squirt- ing expansion coils. But the time is not far distant when these plants will throw aside their squirting coils and substitute expansion devices which do not tend to squirt the liquid ammonia like an atomizer. The liquid ammonia should be allowed to boil in such a vessel that there is ample room for the vapor to escape without dragging along some of the liquid with it. I have tried both kinds, squirting coils and proper expansion vessels, and I would not take an or- dinary coil brine tank for a gift unless I could use it for some other purpose than for a brine tank.

Now to determine the actual displacement of your compressor. If you use the brine system this can readily be done. Get the specific gravity

(4)

42 INDICATING THK

of your brine by means of a hydrometer. If you do not own a hydrometer, weigh equal volumes of your brine and water. Divide the weight of the brine by that of the water. The result is the specific gravity of your brine. Now look up in the tables (see Part IV) the corresponding specific heat. Take several readings of the tem- perature of your brine to tank and also of brine from tank. Average the readings of the inlet brine and also average those of the outlet brine. Subtract the results. This is of course the number of degrees that you have cooled your brine through.

Find the weight of brine circulated per min- ute by your pump. To do this, multiply the strokes of your pump per minute by the length of stroke in inches by the piston area in square inches, and divide the result by 1,728; this gives the cubic feet pumped per minute ; multiply this by the weight of a cubic foot of your brine, to obtain the weight pumped per minute. If your pump is in good condition you should multiply this result by .95, .95 being the probable actual capacity of your brine pump.

Having now the weight in pounds of the brine pumped per minute, multiply this weight by the degrees F. change in temperature of your brine in the brine tank, and multiply this result by the specific heat of your brine. Now, divide the above result by 200, and your final answer is the tons of refrigeration that you are doing per twenty-four hours.

One ton refrigeration in twenty-four hours = 2,000 X 142 B. T. U. ; 142 B. T. U. is the latent heat of liquefaction of ice. 2,000 X 142 = 284,000

AMMONIA COMPRESSOR. 43

B. T. U. per twenty-four hours = ^^ = 200,

nearly, B. T. U. per minute. Twenty-four hours = 1,440 minutes. Expressed in the form of a formula, the above will read:

200

7?— tons refrigeration per twenty-four hours.

/ = temperature warm brine; t^ = temper- ature cold brine.

5 = specific heat of brine.

TV = weight of brine circulated per minute.

Now, turn to your ammonia tables (see Part IV) and find the weig-ht of a cubic foot of vapor of ammonia at the back pressure at which you are running-. Also look up the latent heat of vaporization at this pressure, and the boiling- point of the liquid ammonia. Take the tempera- ture of your liquid ammonia just before it enters the expansion valve. If your liquid pipe is insu- lated, as it should be, this temperature will be about the same as that of the water coming- from your condenser.

Subtract the boiling- point of the ammonia from this temperature. As the specific heat of liquid ammonia is 1, this gives the number of B. T.U. that the liquid must be cooled to bring- it to the boiling- point. As this has to come from the heat of vaporization, we subtract it from the heat of vaporization, leaving- as a result the available cooling- effect in B. T. U. of one pound of liquid ammonia under our conditions. Ex- pressed in the form of a formula, the above be- comes —

R X 200 200 X

~~ ~ ~

44 INDICATING THK

r = heat of vaporization.

/2 = temperature of ammonia at expansion valve.

/3 = temperature of ammonia at boiling- point.

W= pounds of ammonia circulated per minute.

Take the theoretical displacement in cubic feet of your compressor per minute = D; mul- tiply this by the weight of a cubic foot of vapor of ammonia at the back pressure you are using (see Part IV for tables). The result is the theo- retical number of pounds of ammonia pumped by your compressor = Wl . Then Dl —the actual

capacity of your compressor; J9, =jy

EXAMPLES.

JVo. i. — Required the horse power of card (see Fig. id).

The compressor has two single-acting cylin- ders, each twelve inches in diameter, stroke— eighteen inches; forty revolutions per minute; scale of spring, 40.

Solution. — Measure height of lines 1, 2, 3 to 10, with a 40 scale. They measure 88, 88, 88, 58, 35, 22, 13, 7, 4, 1. The sum of these figures is 404. Dividing by 10, the result is 40.4 = M. E. P.

The constant for this compressor is

/Xfl 1.5 X 113 = 33,000 33,000

H. P. =CX »XM. E. P. . • . H. P. = .00514 X 40 X 40.4 = 8.3.

As there are two cylinders, we must obtain also the horse power of the other card ; if it is the same as this card, then the horse power of both cylinders is 8.3 X 2= 16.6.

AMMONIA COMPRKSSOR. 45

If the horse power of the steam engine is 20, then 20 — 16.6 = 3.4 = friction of machine = $••# , 17 per cent of that of the steam cylinders.

This is very good. The friction will usually be about 20 per cent.

No. 2. — Required the refrigeration per day.

Brine pumped per minute = 667 pounds.

Change in temperature of brine =3° F.— t-t\.

Specific heat of brine = .8.

No. 3. — Required the actual capacity of the com- pressor, the theoretical capacity being 100 per cent.

Temperature of liquid ammonia to expansion valve = 70° F.; r = 572, *3 = — 28 for an absolute back pressure of fifteen pounds.

y?=8, r = 572, ^ =70°F., *8= — 28G F.

J~) vx O C\(\

• '. W==- - r I /8 =3.018 pounds per minute. r — »2~r^

The theoretical displacement of the compres- sors is 113X182X40=94 cubic f eet er minute

The weight of a cubic foot of vapor of ammonia at 15 pounds absolute is .056 pounds .*. 94X.056= 5.26 pounds^ W^ the theoretical capacity of the

W ^ 3.018 _,_ compressor .*. jrr = D^ =--~-j£ =57.4 per cent =

rr -^ O« ^D

the actual capacity of the compressor. This is too small, consequently you should find out by your adiabatic line where the trouble is.

46 INDICATING THK

CHAPTER VIII.

SPECIAL FAULTS AS SHOWN BY CARDS.

Fig-. 11 shows a card when the suction valve has too strong- a spring- or a valve that is inclined to stick to its seat. (See distorted heel at a. }

Fig-. 12 shows a card where the line a a is drawn to scale at a vertical distance above the atmospheric line A A, equal to the suction press- ure in the suction pipe. This shows that the suction valve spring- is too strong-.

Fig". 13 shows a card where the line bb has been drawn by connecting- the indicator to the suction pipe and line a a by connecting- the indi- cator to the discharg-e pipe. These lines should be about as shown on the card. The lines a a and bb can best be laid off to scale above A A, corresponding- to the pressures in these pipes, as shown by the pressure g-auge, althoug-h they may be drawn by the indicator pencil if the suc- tion and discharg-e pipes are tapped and con- nected to the indicator.

Fig-. 14 shows a card with a line, a a, drawn to scale at a distance above line A A equal to the pressure in the discharg-e pipe. This indicates too stiff discharg-e valve spring's.

AMMONIA COMPRKSSOK.

47

48

INDICATING THK

AMMONIA COMPRESSOR.

49

50

INDICATING THK

AMMONIA COMPRESSOR. 51

CHAPTER IX.

WET COMPRESSION SYSTEM INDICATING.

Fig's. 15 and 16 are reproduced from cards furnished me by the Fred W. Wolf Co., from an 18X30 inch Linde (wet compression system) compressor, that were taken at the Western Cold Storage Co. plant, on November 9, 1898, on which I have drawn the adiabatic line c d* iso- thermal line a d and the curve of saturation /; d. The scale of spring- for these cards is 60. These diagrams were given me as representative cards, and seem to show that my reasoning-, as applied to the dry compression or water jacket machines, also applies to the wet compression machines, particularly in Fig-. 16.

The wet compression machines differ from the dry compression machines in that the former injects liquid ammonia into the cylinder before compression to take up the heat of compression, while the latter surrounds the cylinder with a water jacket for the same purpose.

THE CURVE OF SATURATION.

If the ammonia in the cylinder at the begin- ning- of compression is a saturated vapor, and if this condition (the state of saturation) is main- tained throughout compression, then there will be a different curve from the adiabatic and iso- thermal traced by the indicator pencil. This is called the curve of saturation. Any point on this curve has its ordinate or vertical distance from V V equal to the pressure in the cylinder, and its abscissa or horizontal distance f rom d Fequal

52

INDICATING THK

AMMONIA COMPRESSOR 53

to the relative volume in cylinder, the initial or (cylinder full) volume being- 1. The ordinate being- obtained by looking- up in a table of the properties of saturated vapor of ammonia the pressure corresponding- to the weig-ht of a cubic foot of vapor at this point, this weig-ht being- the product of the relative volume at this point and the weig-ht of a cubic foot of vapor at the absolute back pressure of the card. Curves b d^ Figs. 15 and 16, are curves of saturation. This curve can be readily determined, approximately, from the tables of the properties of saturated vapor of ammonia in the following- manner:

Find from the tables the volume in cubic feet per pound of the vapor at the absolute back pressure of the card. Multiply this value by .9, .8, .7, .6, .5, .4, .3, .2, .1, and note from the tables the absolute pressures corresponding- to these new volumes. These pressures are points on the curve of saturation for values, .9, .8, .7, .6, .5, .4, .3, .2, .1 of v.

For example, let the absolute back pressure be twenty-one pounds per square inch. We find from the tables that the number of cubic feet of vapor per pound at this pressure is approxi- mately 12.834. Then it follows that—

12.834 X. 9=11. 55 cu. ft. per Ib. •= 23.5 Ibs. per sq. inch

12.834 X. 8=10.27 " = 26.5

12.834X.7= 8.98 " =310

12.834X.6= 7.70 " = 35.8

12.834X.5= 6.42 " = 43.0

12.834X.4= 5.13 " = 54.6

12.834X.3= 3.85 " = 59.7

12.834X.2= 2.57 " =113.7

12.834X.1= 1.28 =232.0

Laying- off these values of pressures found on the vertical lines to scale at volumes z;.fl, z>.8, v,^

54

INDICATING THK

AMMONIA COMPRESSOR. 55

r.»;> z'.5> r4> v.$i ^.2* ^ i» from the vacuum line, we have the desired points on the curve of satura- tion.

LIMITS OF COMPRESSOR.

From the above it follows that the adiabatic curve will be traced when no heat is taken from or given to the gas during- compression. The isothermal curve will be drawn if the gas is maintained at the same temperature that it has at the beginning- of compression. Theoretically, the g-as should be quite cold at the beginning- of compression, say from 10° below 0^ F. to 10° above 0° F. It will be seen that compressors using water jackets could never maintain this line unless they had jacket water as cold or colder than these temperatures of gas at the beginning of compression. As the jacket water usually rang-es anywhere from 50° F. to 100° F., it is clear that no heat can be taken from the compressed g-as until it has reached this temperature.

This will explain why the actual curve of com- pression follows the adiabatic curve part of the way, and then tends toward the isothermal curve. Where the actual compression curve leaves the adiabatic, is the point of the stroke where the jacket water is just beginning to "get in its work." Therefore, if any one shows you a card from a water jacketed dry compressor that approaches the isothermal line for the first half of the stroke, you would better make up your mind that the card is wrong.

It will be seen in Figs. 15 and 16 that the curve of saturation b d follows very closely the isother- mal curve. In wet compression machines this curve (the curve of saturation ) is aimed at bv

56 INDICATING THE

injecting enough liquid ammonia into the cylin- der to take up the heat of compression. If this works as well practically as it does by theory, then the curve of saturation is possible, and therefore quite a reduced area of card is obtained, indicating less power required to compress the ammonia.

As it is not my desire to compare the relative merits of the wet and dry compressors, I will only add that to be fair when comparing one with the other the question should be thoroughly in- vestigated as to whether there are factors that enter into the value of each machine other than those shown by the indicator cards, and also to note that cards 15 and 16, which are taken as representative cards of the wet compression system, are almost identical with what is ob- tained from dry compression machines, particu- larly Fig. 16.

AMMONIA COMPRESSOR. 57

CHAPTER X.

INSTRUCTIONS FOR CONNECTING INDICATOR TO MACHINE.

In regard to connecting- the indicator to the compressor and arranging* for the drum motion, I refer the reader to Chapters II and III of Part II; how to take the diagrams, to Chapter IV, Part II. I advise the use of a reducing- wheel, as explained in Chapters VII and VIII, Part III.

The reducing- wheel will be found very accu- rate and simple, and can be used with any of the indicators described. Most of the indicator manufacturers have these reducing- wheels in stock, specially adapted to their particular make of indicator.

In making- the ammonia connection with the compressor cylinder, I advise the use of a ^2-inch pipe connection, made from a solid piece of iron or steel, having- a hole Y% inch diameter drilled throug-h it. The reason for using- so small a bore is to reduce the clearance as much as possible. This connection can be capped when not in use, or, better still, fitted with a >^-inch cock, in which the hole in the plug- has been bushed down to Y% inch diameter. I advise the use of Coffin's averaging- instrument for obtaining- the mean effective pressure of cards. This instrument gives you the mean effective pressure direct without the intermediate steps of calculation necessary with the common plani- meter, and also a neat board upon which to measure the card.

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THE

REFRIGERATING MACHINE

PART II.

INDICATING THE STEAM ENGINE.*

CHAPTER I.

THE STEAM ENGINE INDICATOR.

The steam engine indicator, invented by James Watt, and long- kept secret, was for many years after its secret became known, strangely neglected by most makers and users of steam engines.

The earlier forms of the instrument, which preceded that invented by Richards, were so imperfect and so ill adapted to engines running at other than very low speeds, that their indi- cations were often misleading, more often unin- telligible, and seldom of much value beyond revealing the point of stroke at which the valves opened and closed — a most valuable service, alone worth the cost of an indicator, but only a small part of the service to be obtained from a really good instrument.

The general principles, on which the best type of steam engine indicator is designed, may be briefly stated as follows:

A piston of carefully determined area is nicely fitted into a cylinder so that it will move

*Reprinted by courtesy of Crosby Steam Gage and Valve Co. from their book on indicator practice.

59

60 INDICATING THE

up and down without sensible friction. The cylinder is open at the bottom and fitted so that it may be attached to the cylinder of a steam engine and have free communication with its interior, by which arrangement the under side of the piston is subjected to all the varying pressures of the steam acting- therein. The upward movement of the piston — due to the pressure of the steam — is resisted by a spiral spring within the cylinder, of known elastic force. A piston rod projects upward through the cylinder cap and moves a lever having at its free end a pencil point, whose vertical move- ment bears a constant ratio to that of the piston. A drum of cylindrical form and covered with paper is attached to the cylinder in such a man- ner that the pencil point may be brought in contact with its surface, and thus record any movement of either paper or pencil. The drum is given a horizontal motion coincident with and bearing a constant ratio to the movement of the piston of the engine. It is moved in one direc- tion by means of a cord attached to the cross- head, and in the opposite direction by a spring within itself.

When this mechanism is properly adjusted and free communication is opened with the cyl- inder of a steam engine in motion, it is evident that the pencil will be moved vertically by the varying pressure of steam under the piston; and as the drum is rotated by the reciprocating mo- tion of the engine, if the pencil is held in contact with the moving paper during one revolution of the engine a figure or diagram will be traced representing the pressure of steam in the

STEAM KNGINE. 61

cylinder, the upper line showing- the pressure urging- the piston forward, and the lower the pressure retarding- its movement on the return stroke.

To enable the engineer to more correctly interpret the nature of the pressures, the line showing- the atmospheric pressure is drawn, which indicates whether the pressure at any part is greater or less than that of the atmos- phere.

From such a diagram may be deduced many particulars which are of supreme importance to engine builders, engineers and the owners of steam plants.

WHAT IS THE GOOD OF AN INDICATOR?

This question was asked by a young- engi- neer who had come to examine and purchase an indicator, with a view to rendering his services of greater value to his employer, by a knowledge and use of that instrument. His question was overheard by the proprietor of a large establish- ment, who took occasion to reply as follows:

"I will tell you what good an indicator did at our works. Our steam engine was not giving sufficient power for our business, and we ex- pected to be obliged to procure a larger one. A neighbor suggested that we have our engine indicated to see if we were getting the best service obtainable from it. This was done, and the result was, that when the valves were prop- erly adjusted and other slight changes made, we had ample power, and the improved condition of the engine made a reduction in our coal bills during the following year of $500."

62 INDICATING THE

Another case: An expert engineer was called to indicate several locomotives just completed by one of our prominent locomotive builders, who had in use a large Corliss engine, which had been running- only a few months. When the loco- motives were indicated, the proprietor proposed that the indicator be applied to the Corliss engine, the engineer of which remarked: "Guess you '11 find her all right, as she 's running- fine." \The first card showd that nearly all the -work ivas being done at one end of the cylinder. The valves were chang-ed and a great improvement was apparent in the running- of the engine, while the actual consumption of coal was re- duced from an averag-e of 3,370 pounds per day, before the chang-e was made, to 2,338 pounds afterward.

These two instances are valuable in showing " the g-ood of an indicator."

Items of Information to be Obtained by the Use of the Indicator. — The arrang-ement of the valves for admission, cut-off, release and compression of steam.

The adequacy of the ports and passages for admission and exhaust; and when applied to the steam chest, the adequacy of the steam pipes.

The suitableness of the valve motion in point of rapidity at the right time.

The quantity of power developed in the cyl- inder, and the quantity lost in various ways: by wire drawing, by back pressure, by premature release, by mal-adjustment of valves, leakage, etc.

It is useful to the designers of steam en- gines in showing the distribution of horizontal

STEAM ENGINE. 63

pressures at the crank pin, through the momen- tum and inertia of the reciprocating- parts, and the angular distribution of the tangential component of the horizontal pressure; in other words, the rotative effect around the path of the crank.

Taken in combination .with measurements of feed water and the condensation and measure- ment of the exhaust steam, with the amount of fuel used, the indicator furnishes many other items of importance when the economical genera- tion and use of steam are considered.

For every one of these purposes it is import- ant that the diagram traced by the indicator should truly represent the path of the piston and the pressure exerted on both sides of the piston at every point of that path.

INDICATOR DIAGRAMS.

The degree of excellence to which steam engines of the present time have been brought is due more to the use of theindicator than to any other cause, as a careful study of indicator diagrams taken under different conditions of load, pressure, etc., is the only means of becom- ing familiar with the action of steam in an engine, and of gaining a definite knowledge of the vari- ous changes of pressure that take place in the cylinder.

An indicator diagram is the result of two movements, namely: a horizontal movement of the paper in exact correspondence with the movement of the piston, and a vertical move- ment of the pencil in exact ratio to the pressure exerted in the cylinder of the engine; con- sequently, it represents by its length the stroke

64 INDICATING THE

of the engine on a reduced scale, and by its height at any point, the pressure on the piston at a corresponding- point in the stroke. The shape of the diagram depends altogether upon the manner in which the steam is admitted to and released from the cylinder of the engine; the variety of shapes given from different en- gines, and by the same engine under different circumstances, is almost endless, and it is in the intelligent and careful measurement of these that the true value of the indicator is found, and no one at the present day can claim to be a competent engineer who has not become familiar with the use of the indicator, and skillful in turning to practical advantage the varied information which it furnishes.

A diagram shows the pressure acting- on one side of the piston only, during both the forward and return stroke, whereon all the changes of pressure may be properly located, studied and measured. To show the corresponding press- ures on the other side of the piston, another dia- gram must be taken from the other end of the cylinder. When the three-way cock is used, the diagrams from both ends are usually taken on the same paper, as in Fig. 9.

ANALYSIS OF THE DIAGRAM.

The names by which the various points and lines of an indicator diagram are known and des- ignated are given below, and their significance fully explained. (See Fig. 1.)

The closed figure or diagram, CD E F G H, is drawn by the indicator, and is the result of one indication from one side of the piston of an

STEAM ENGINE. 65

engine. The straight line A B is also drawn by the indicator, but at a time when steam connec- tion with the engine is closed, and both sides of the indicator piston are subjected to atmospheric pressure only.

The straight lines O X, O ^and/TT, when required, are drawn by hand as explained below, and may be called reference lines. Y

H-

B

FIG. 1. DIAGRAM LINES EXPLAINED.

The admission line C D shows the rise of pressure due to the admission of steam to the cylinder by the opening- of the steam valve. If the steam is admitted quickly when the engine is about on the dead center this line will be nearly vertical.

The steam line D E is drawn when the steam valve is open and steam is being- admitted to the cylinder.

The point of cut-off E is the point where the admission of steam is stopped by the closing of the valve. It is sometimes difficult to determine

66 INDICATING THE

the exact point at which the cut-off takes place. It is usually located where outline of diagram changes its curvature from convex to concave.

The expansion curve E F shows the fall in pressure as the steam in the cylinder expands behind the moving- piston of the engine.

The point of release F shows when the ex- haust valve opens.

The exhaust line F G represents the loss of pressure which takes place when the exhaust valve opens at or near the end of the stroke.

The back pressure line ^^showsthe pressure against which the piston acts during* its return stroke. On diagrams taken from non-condens- ing engines it is either coincident with or above the atmospheric line, as in Fig. 1. On cards taken from a condensing engine, however, it is found below the atmospheric line, and at a dis- tance greater or less according to the vacuum obtained in the cylinder.

The point of exhaust closure H is the point where the exhaust valve closes. It cannot be located very definitely, as the change in pressure is at first due to the gradual closing of the valve.

The compression ctirve H C shows the rise in pressure due to the compression of the steam remaining in the cylinder after the exhaust valve has closed.

The atmospheric line A B is a line drawn by the pencil of the indicator when its connections with the engine are closed and both sides of the piston are open to the atmosphere. This line represents on the diagram the pressure of the atmosphere, or zero of the steam gauge.

STEAM ENGINE. 67

REFERENCE LINES EXPLAINED.

The zero line of pressure, or line of absolute vacuum OX, is a reference line, and is drawn by hand 14T\ pounds by the scale, below and parallel with the atmospheric line. It represents a per- fect vacuum, or absence of all pressure.

The line of boiler pressure J K v& drawn by hand parallel to the atmospheric line and at a distance from it, by the scale equal to the boiler pressure shown by the steam gauge. The differ- ence in pounds between it and the line of the dia- gram D E shows the pressure which is lost after the steam has flowed through the contracted passages of the steam pipes and the ports of the engine.

The clearance line O T is another reference line drawn at right angles to the atmospheric line and at a distance from the end of the dia- gram equal to the same per cent of its length as the clearance bears to the piston travel or dis- placement. The distance between the clearance line and the end of the diagram represents the volume of the clearance and waste room of the ports and passages at that end of the cylinder.

DERANGED VALVE MOTION.

Fig. 2 shows two diagrams, one from each end of the cylinder of a single-valve high press- ure engine. This valve admits the steam over its ends and exhausts inside. The derangement is caused by the valve stem being too long; con- sequently, at the back end the diagram shows that the steam was admitted late, cut off early, exhausted early and the exhaust valve closed late, so that there is little or no compression.

68 INDICATING THE

The diagram at the crank end shows the opposite defects, viz.: Steam is admitted too soon and carried too far on the stroke, the exhaust valve is opened too late and closed too soon to get the steam well out of the cylinder, causing1 excessive back pressure — even greater than the boiler pressure as shown by the loop at the top.

To remedy this derangement, the valve stem should be shortened by the screw threads at one end. It may then be found that the steam valve

FIG. 2.

opens a little too late at both ends, and it will therefore be necessary to turn the eccentric ahead on the shaft until both diagrams resemble the figures shown in the heaviest lines.

UNITS OF MEASUREMENT AND TECHNICAL TERMS.

All substances of whatever nature are meas- urable, and their measurements are referable to some established unit, to be properly ex- pressed and dealt with. An intimate knowledge of some of these is indispensable to the engineer; a few are here briefly defined:

The unit of linear measurement is the inch or one-twelfth part of a foot.

STEAM ENGINE. 69

The unit of superficial measurement is the square inch.

The unit of so lid measurement'^ the cubic inch.

The unit of fluid pressure is the pound avoir- dupois, consisting of 7,000 grains.

The unit of elasticity, or the pressure exerted by elastic fluids, is, for popular use, one pound on one square inch.

The unit of work or power is one pound lifted twelve inches, or in other words, one pound of force acting- through one foot of distance, and is called the foot-pound.

Horse Power. — The standard used for meas- uring- the power of a steam engine is the horse power. It was originally determined by James Watt from experiments made on London dray horses. It is considerably above the power of an ordinary horse and is now simply an arbitrary standard. It is equal to 33,000 foot-pounds ex- erted during- one minute of time, or 550 foot- pounds during- one second. As a foot-pound is the amount of work done in raising one pound through the distance of one foot, an equivalent amount of work would be raising half a pound two feet, or twelve pounds one inch.

Indicated horse power is the horse power of an engine as found by the use of a steam engine indicator, and is thus expressed: I. H. P.

Net horse power is the indicated horse power of an engine, less the horse power which is con- sumed in overcoming its own friction.

Wire drawing, as applied to steam, is the re- ducing of its pressure, due to its flowing through restricted or crooked pipes and passages.

Absolute pressure is pressure reckoned from

70 INDICATING THE

absolute vacuum; in other words, it is the press- ure of any fluid as shown by a pressure gauge, with the weight or pressure of the atmosphere added thereto.

Initial forward pressure in a cylinder is the pressure acting on the piston at or near the beginning of the forward stroke.

Terminal forward pressure is the pressure above the line of perfect vacuum that would exist at the end of the stroke if the steam had not been released earlier. It may be found by continuing the expansion curve to the end of the diagram, as in Fig. 1 at F, or it may be taken at the point of release. This pressure is always measured from the line of perfect vacuum, hence it is the absolute terminal pressure.

Mean effective pressure is the average of all the steam pressure which acts on one side of the piston to move it forward, less all the steam pressure which acts on the other side of the piston to retard it. It is expressed thus : M. E. P.

Piston displacement is the space in the cylin- der swept through by the piston in its travel. It is reckoned in cubic inches, and is found by multiplying the net area of the piston in inches, by the length of stroke in inches, allowance being made for the piston rod.

Clearance is all the waste room or space at either end of the cylinder, between its head and the piston when on a dead center, including the counterbore and the ports, up to the face of the closed valves.

Sensible heat is the temperature of any body, as air, water or steam, which may be measured by the thermometer.

STEAM ENGINE. 71

Specific heat is the quantity of heat required to raise one unit of weight of the substance through one degree of temperature, measured in thermal units.- When the pressure remains constant Regnault found the specific heat for superheated steam to be 0.4805 of a thermal unit.

The unit of heat, or thermal unit, is the quan- tity of heat required to raise the temperature of one pound of water from 62° to 63° F.

Mechanical Equivalent of Heat. — It has been found by experiment that if one pound of pure water at 62° F. be raised to 63° F., that energy is exerted equivalent to lifting 778 pounds one foot high, or one pound 778 feet high. This energy is called the mechanical equivalent of one thermal unit of heat, and it is usually designated by the letter / and its reciprocal, or Tfg, by A.

Saturated Steam. — When steam is formed in a closed vessel in contact with its own liquid, it is said to be saturated, and it will have a certain definite pressure and density corresponding to each different temperature. If, at the same time, the steam contains no liquid in suspension, it is said to be dry and saturated.

Superheated Steam. — If, after all the liquid has been converted into steam, more heat be added, the temperature will rise and the steam is said to be superheated, because its tempera- ture will be greater than that corresponding to saturated steam of the same pressure. The amount of superheating will vary according to the conditions under which it occurs — that is to say, whether the volume of the containing vessel varies or remains constant.

72 INDICATING THE

CHAPTER II.

HOW AND WHERE TO ATTACH THE INDICATOR.

The indicator should be attached close to the cylinder whenever practicable, especially on high speed engines. If pipes must be used they should not be smaller than half an inch in diame- ter, and as short and direct as possible ; if long- pipes are needed they should be slightly larger than half an inch, and covered with a non-con- ducting material.

FIG. 3.

Diagrams should be taken from both ends of the cylinder of an engine. If the diagram from one end is satisfactory it is not safe to assume that one taken at the other end will be equally so; it is often otherwise, owing to the varying conditions usually found; the lengths of thor- oughfares, the points of valve opening and clos- ing, and the lead, are variable and should be carefully adjusted to secure the best results, and this can only be done through the instrumen- tality of an indicator.

When only one indicator is employed, it is generally attached to a three-way cock (Fig. 3),

STEAM ENGINE. 73

which is located midway in the line of pipe, con- necting- the holes at either end of the cylinder; by this arrangement diagrams can be taken from either end simply by turning- the handle of the three-way cock. In such a case, the second diagram should be taken as quickly as possible after the first, so as to be under like conditions of speed, pressure and load.

The indicator can be used in a horizontal posi- tion, but it is more convenient to take diagrams when it is in a vertical position, and this can gen- erally be -obtained, when attaching to a vertical engine, by using a short pipe with a quarter up- ward bend. No putty or red lead should be used in making any joints, as particles of it may be carried by the steam into the indicator, and great harm result therefrom ; if a screw fits loosely, wind into the threads a little cotton waste, which will make a steam tight joint. The indicator should never be set so as to communicate with thoroughfares where a current of steam will jlow past the orifice leading to the indicator, as the diagrams taken under such conditions would be of no practical value.

The cylinders of most modern steam engines are drilled and tapped for the indicator and have plugs screwed into the holes, which can readily be removed and the proper indicator connections inserted. But when this is not the case, the engineer should be competent to do it under the directions here given.

When drilling holes in the cylinder the heads should be removed if convenient, so that one may know the exact position of the piston, the size of ports and passages, and be able to remove

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74 INDICATING THE

every chip or particle of grit which might other- wise do harm in the cylinder or be carried into the indicator and injure it. When the heads can- not be taken off, it can be arranged so that a little steam may be let into the cylinder, when the drill has nearly penetrated its shell, so that the chips may be blown outward, care being taken not to scald the operator.

Each end of the cylinder should be drilled and tapped for one-half-inch pipe thread. The holes must always be drilled into the clearance space, at points beyond the range of the piston when at the end of the stroke, so as not to be ob- structed by it, and away from steam passages, to avoid strong currents of steam. By placing the engine on a dead center, it is easy to tell how much clearance there is, and the hole should be drilled into the middle of this space; the same process should be repeated at theotherendof the cylinder.

On horizontal engines the most common prac- tice is to drill and tap holes in the side of the cylinder at each end, and insert short half-inch pipes with quarter upward bends, into which the indicator cocks may be screwed ; on some hori- zontal engines it may be more convenient to drill and tap into the top of the cylinder at each end, and screw the cocks directly into the holes. On vertical engines, for the upper end of the cylinder the cock may be screwed into the upper head or cover, and for the lower end, into the side of the cylinder, after drilling and tapping the necessary hole. It is preferable to drill the holes in the sides of a cylinder rather than the heads, because the former gives better results and requires less pipe and fittings.

STKAM ENGINE. 75

Before deciding- just where to drill the holes it is wise to consider all the conditionsof the case and devise the whole plan for indicating1 the engine.

Sometimes a drum motion can be erected more advantag-eousry in one place or position in the engine room than another, or one kind may be better adapted for a given place than another. Again, the type of engine and position of the steam chest, the kind of cross-head and the best means for attaching to it, the position of the eccentric, its rods and connections, -all should be taken into account when determining- the best places to drill the cylinder and locate the indica- tor, in order to secure a proper connection with the reducing motion, a perfectly free passag-e for steam to the indicator and the most convenient access to the instrument for taking diagrams.

76

INDICATING THK

CHAPTER III.

THE DRUM MOTION.

The motion of the paper drum may be derived from any part of the engine which has a move- ment coincident with that of the piston. In general practice and in a large majority of cases the cross-head is chosen as being- the most relia- ble and convenient part, and for this purpose it is drilled and tapped for an iron stud or pin to be screwed in to it. This stud should be long- enough, in most cases, to reach about six inches beyond the outer surface of the cyl- inder. The movement of the cross-head must be reduced from whatever it actually is, to about three inches, or the leng-th of the diagram to be taken, FlG- 4- and this reduced motion

must be in exact ratio to the motion of the piston. To obtain this reduced motion a variety of means may be employed, any one of which calls forth the ingenuity and skill of the engineer. The reducing lever in some one of its various forms is easily made, and can be adapted to suit almost any conditions.

The slotted lever (Fig. 4) is a common form of this device, and answers very well for large

STEAM ENGINE.

77

and quick running- engines. It should be made of straight grained pine, one inch or more in thickness, about six inches wide at the top, where there is a hole for a bolt, and tapering- to four inches at the bottom, where there is a slot about six inches long- and of the same width as the diameter of stud in the cross-head, which gives it a vibrating motion. This lever is suspended by a bolt from the ceiling or from a truss or frame overhead prepared for that purpose, in such a manner as to permit it to swing edgewise and parallel with the guides. It must hang plumb when the stud in the cross-head is in the slot and the piston is at mid- c stroke; in this position the slot should extend an inch or more above the stud, for play.

To find the point at which to attach the cord, divide the length of the lever by the length of the piston stroke, and multiply the quotient by the required length of the dia- gram, and the product will be the proper distance from the pivot to the point of attachment.

The slotted lever with a cord arm, which can be set at any desired angle to the main lever, is shown in Fig. 5. This is a convenient device when it is found necessary to attach the reduc- ing motion to the floor, which may be done by fastening down with lag screws or bolts a suit- able piece of timber, to which the lever is pivoted, so that it will vibrate edgewise with the move- ment of the engine. It may also be attached

FIG. 5.

78

INDICATING THE

overhead in the same manner as the plain slotted lever. The lever must stand plumb when the piston is at mid-stroke, at which time the cord arm, a, must be fixed at such an angle as to have the cord, c, draw at right angles to its longitu- dinal axis, and in the plane of its vibration; the direction of the cord may have any necessary angle with horizontal line, but it must be at right

angles with the cord arm at mid-stroke. The point of attach- ment for the cord is found by the same arithmetical rule as given for Fig. 4.

The Brumbo pul- ley, shown in Fig. 6, is another form of reducing lever, and one more generally used by engineers, especially on loco- { 1 motives. It can be

FIG. 6. quickly and cheaply

made, and can be used on almost any engine. The swinging lever, E, is a strip of pine board three or four inches wide, and at least one and a half times as long as the piston stroke. It is sus- pended by a bolt or screw from a frame or truss overhead, constructed for that purpose, and is connected at its lower end by the wooden link, F, of convenient length (say about one-half the length of stroke) to the usual stud or pin at- tached to the cross-head. The sector, S, also made of wood, with a groove in its lower circular

STEAM ENGINE. 79

edge for the cord to run in, is screwed to the upper end of the pendulum, so that its center will exactly coincide with the center of the bolt on which it swing's. The radius of the sector, which is necessary to give the proper motion to the drum to obtain the desired length of the diagram, can be found as follows: Divide the length of the lever by the length of the piston stroke, and multiply the quotient by the length of the diagram desired, and the product will be the required radius, all the terms being expressed in inches. For example: If the lever is thirty inches long and the piston stroke twenty inches, and we wish to obtain a diagram three inches long, we have 30 inches -*- 20 inches = 1>£ inches; 1>2 inches X 3 inches — 4j^ inches, the radius required to give a 3-inch diagram.

When the conditions are favorable, the lever should be hung so that it will swing in a vertical plane, parallel with the guides and in line with the indicator, as this arrangement is the most simple, and the use of guide pulleys is avoided. It is not absolutely necessary, however, that the lever shall swing in a vertical plane, but it may swing in a plane at any angle thereto, where the conditions require it. In such cases, a man's ingenuity and inventive faculty must aid him. A link made of a thin strip of steel, that will twist a little, is in some cases very convenient.

When the cross-head is at mid-stroke the lever must hang plumb, and the pin which connects its lower end to the link must be as much below the line of motion of the stud in the cross-head H, as it sweeps above that line at either end of the stroke. See cut for illustration of this point,

80

INDICATING THE

which is important. The cord must lead from the sector in about the same plane with its swing*. Carrying pulleys should be avoided whenever possible, but whatever number is necessary should be firmly placed. The swing-ing- arm of the guide pulley on the indicator should always be adjusted in the direction from which the cord is received. Some engines are furnished with a drum motion of this kind, made of steel with nicely fitted joints, which can be readily attached to the engine, and are very convenient to use.

FIG. 7.

The pantograph, illustrated in Fig. 7, is another style of reducing motion. Although theoretically it gives a perfect motion, owing to its many joints it may soon become shaky and give erroneous results, unless it is very nicely made and carefully used. When the indicator is applied to the side of the cylinder the panto- graph works in a horizontal plane. The pivot end B rests on a post or other support set opposite to the middle of the guides, and the working end A receives motion from the cross-head — to which

STEAM ENGINE. 81

it is attached by a suitable iron with a hole drilled in it for the stud A to work in. By ad j usting the support for the pivot end to the proper height and at a proper distance from the guides, the cord may be carried directly from the pin E to the indicator without the need of carrying- pulleys.

The reducing -wheel is another device for giv- ing the proper motion to the paper drum. Al- though old in principle, and as formerly made not highly approved by experienced engineers, this style is now coming- into more g-eneral use, and the superior manner in which it is desig-ned and constructed seems to warrant this chang-e — especially on short-stroke engines which re- quire only a short cord. Its portability and con- venience of application also tend to make it a favorite, especially with young engineers. It is usually clamped to the frame of the engine, in a direct line from the indicator to the stud in the cross-head, thus avoiding the need of guide pul- leys. This is considered the only practical drum motion for an oscillating engine.

Whatever drum motion mechanism is used, its accuracy can be easily tested in the following manner : Lay off on the guides, points at one- quarter, one-half and three-quarters of the stroke. Connect the indicator with the drum mo- tion in the same manner as for taking diagrams. When the cross-head is on either dead center, touch the pencil to the paper and make a vertical mark, and in the same way make vertical marks when the cross-head reaches each successive quarter point on the guides. If the marks are exactly at fourths on the card, the motion of the cross-head has been accurately reduced.

82

INDICATING THE

The directions here given for constructing and arranging- drum motions are general; special cases may require modification of the forms and special adaptation of the means here described, all of which call forth the ingenuity and skill of the engineer.

Fig. 8 X shows a pantograph device at mid- stroke. This is made of bar iron nicely riveted together. The indicator cord may be attached at b. The end a is attached to a pin on the cross-head. The fixed fulcrum is at c. a, b and c must always lie in the same straight line, and e d, b n, par- allel and equal to f g. Also, af : nf= stroke of piston to length of indicator diagram.

Fig. 8 Y is a device used at the Massachusetts Institute of Technology. f\<$> a rod mov- ing in a slide parallel to the piston rod. Link b d is at- tached toy, and link a e to the cross-head. «, b and c must always lie in the same straightline.

stroke of piston to length of indi- cator diagram. The cord is hook- ed on a pin at^; it is well to have a pin for each indi- cator used.

STEAM ENGINE. 83

Fig-. 8 Z is a device by Armand Stevart for long- strokes, a and b are fixed ends of cord wrapped around pulley D. Indicator cord is attached to small pulley d and passes around g-uide pulley e. D and <^are attached to cross- head. Dia. D -*- dia. d = stroke piston -*- the difference between stroke of piston and leng-th of card.

84 INDICATING THE

CHAPTER IV.

HOW TO TAKE DIAGRAMS.

When the indicator has been placed in posi- tion and a correct drum motion obtained, it is next necessary to adjust the length of the cord so that the drum will not strike the stops at either ex- treme of its rotation. Find about the length of cord required and make a loop at the end, so that when the hook on the short piece of cord connected with the indicator is hooked in, the cord will be a little too long. Take up the extra length by tying knots in the cord until the drum rotates without striking either stop. This method may seem rather primitive, but it has been adopted by many of our best engineers after trying the various devices for shortening the cord.

The paper or card should be wrapped smoothly around the drum ; have the two lower edges come evenly together as they meet after being passed under the clip; when in this posi- tion, the paper may be slipped down as far as the shoulder in the clip; a little practice will en- able one to do this with facility.

After the cord is adjusted and a paper wrapped on the drum, open the indicator cock and allow the piston to play until the instrument has been thoroughly warmed by the steam, then gently press the pencil on the paper by the wooden handle. After the pencil has remained on the paper during one or more revolutions, draw it back, close the cock and again gently

STEAM ENGINE. 85

press the pencil on the paper and take the at- mospheric line.

The pressure of the pencil on the paper can be adjusted by screwing- the handle in or out, so that when it strikes the stop there will be just enough pressure on the pencil to give a distinct fine line. The line should not be heavy, as the friction necessary to draw such a line is sufficient to cause errors in the diagram.

After the diagram has been taken disconnect the cord, to avoid any unnecessary wear on the drum.

On locomotives and engines, the speed of which is so great that it is difficult to hook in the loop, arrangements can easily be made so this will not have to be done. At the further end of the arc on the Brumbo pulley insert an ordinary screw eye. Drive another screw eye firmly into a small hole drilled in the center of the end of the bolt on which the bar swings. The cord from the indicator can then be carried through the eye at the end of the arc, and then through the eye in the end of the bolt and back to some conven- ient point near the instrument where it can be easily reached by the operator. Connect the cord with the instrument and draw it through the eyes until the drum will not strike the stops at its extreme positions. Then at the point of the cord just before the eye at the end of the arc, tie a small ring. When the cord is drawn taut by the operator, the ring stops the cord when it has been drawn through just enough to give the proper motion to the drum. As soon as the diagram and atmospheric line have been taken, slacken the cord and the drum will stop. This

86 INDICATING THE

arrangement is very convenient on locomotives, as the cord can be drawn taut with one hand while the diagram is taken with the other.

Make notes on the card of as many of the fol- lowing- facts as possible: The day and hour of taking- the diagram; the kind of engine from which the diagram is taken, which end of the cylinder and which engine, if one of a pair ; the diameter of the cylinder, the leng-th of the stroke, the diameter of the piston rod, the number of revolutions per minute and the position of the throttle; the atmospheric pressure; the steam pressure at the boiler and at the engine, by the g-aug-e ; the vacuum by the g-aug-e on condenser and the temperature of the feed at the boiler; if the engine is compound, the pressure in the re- ceiver; the scale of the spring- used in the indi- cator; the volume of the clearance at each end of the cylinder, and what per cent of the piston displacement each of these volumes is. (Direc- tions for ascertaining- the volume of the clearance and what per cent that volume is of the piston displacement, are given on pag-es 97 to 100.)

It is often useful to make notes of special circumstances of importance, such as a descrip- tion of the boiler, the diameter and leng-th of the steam and exhaust pipes, the temperature of the feed water, the quantity of water consumed per hour, etc.

On a locomotive, note the time of passag-e between mile posts in minutes and seconds, from which, when the diameter of the drivers is known, the number of revolutions per minute may be calculated. Note also the position of the throttle and the link, the size of the blast

STEAM ENGINE.

87

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orifice, the weight of the train, and the gradient.

On diagrams from marine engines, note, in

addition to the general facts, the speed of the

88 INDICATING THE

ship in knots per hour, the direction and force of the wind, the direction and state of the sea, the diameter and pitch of the screw, the kind of coal, the amount consumed, and the ashes made per hour.

STEAM ENGINE. 89

CHAPTER V.

HOW TO FIND THE POWER OF AN ENGINE.

To find the power actually exerted within the cylinder of a steam engine, it is necessary to ascertain separately three factors and the product of their continued multiplication. These factors are: The net area of the piston, designated by the letter a; the mean velocity or speed of the piston, designated by 5; and the mean effective pressure urging- the piston forward, desig-nated by M. E. P.

The Piston Area. — This, at the back end, is the same as the area of cross-section of the cyl- inder; at the crank end it is the same, less the area of cross-section of the piston rod. These areas may be found from their diameters in a table of the areas of circles, or be computed by multiplying- the square of the diameter in inches by the approximate number 0.7854.

The Mean Piston Speed. — The mean of the constantly varying- speed of the piston is found by multiplying- twice the leng-th of the stroke measured in feet, by the number of revolutions of the crank shaft per minute, which should be carefully ascertained by taking- the mean of many counting's, or the reading's of a speed counter during- a considerable time. The mean piston speed will be expressed in terms of feet per minute.

7^he Mean Effective Pressure. — There are several approximate methods for computing- the mean effective pressure, one of which is to

90

INDICATING THB

divide the diagram into ten equal parts, as shown in Fig*. 9. Then through the points of division draw lines, which are called ordinates, at right angles to the atmospheric line. The mean heights or pressures of the small areas thus formed are indicated by the dotted lines midway between the ordinates.

The mean effective pressure of the whole (of each) diagram may now be found by measuring (on the dotted lines) the mean pressure in each of the small areas with the scale corresponding to the spring used in taking the diagram.

FIG. 9.

Diagrams from Hartford engine. Cylinder, 16X24 inches. Boiler pressure,

87 pounds. Vacuum per gauge, 23l/2 inches. 130

revolutions per minute.

The sum of these mean pressures, divided by 10, the number of divisions, will give the mean effective pressure sought, in pounds per square inch.

If a diagram has many irregularities of out- line, it may be necessary to divide it into twenty equal divisions to insure a correct measurement of the pressures; in such a case we divide the sum of the pressures by 20 instead of 10. In

STEAM ENGINE.

91

other cases, when irregularities occur only in a part of a diagram, it is only necessary to subdi- vide one or more of the ten divisions to insure greater accuracy in that part; in such £ case we must measure the pressure in each subdivision and divide their sum by 2 to get the mean press- ure of that division. (See Fig. 11 for a full illus- tration of this method.)

If the scale is not at hand the heights of the divisions may be pricked or marked off on a strip of paper, one after the other continuously until all are measured; then the distance from the end

FIG. 10.

of the strip to the last mark will represent the sum of all the measurements, which can be measured in inches with an ordinary rule. This quantity, divided by the number of divisions in the diagram — or diagrams, if there are two — and multiplied by the scale of the spring used, will give the average of mean effective pressure, the same as by the other method.

When there is a loop in the diagram, as in Fig. 10, the area inclosed in the loop should be sub- tracted from the other part, as it represents loss of efficiency.

The quickest and most accurate method for

92 INDICATING THE

measuring' the diagram and finding the mean effective pressure is by the use of Amsler's Polar planimeter. With careful manipulation, the planimeter will give the exact area of a diagram in square inches and decimal parts thereof, to hundredths of a square inch, and the tedious process of dividing- the diagram into equal parts and measuring their average press- ures or heights, with the liability of making errors, is avoided.

Measure the diagram with the planimeter, as directed in Chapter VII. Divide the number of square inches area thus found by the length of the diagram, expressed in inches and decimals, and the result will be the average heig"ht of the dia- gram. Multiply this average height by the scale corresponding to the spring used in taking the diagrams, and the result will be the mean effective pressure. It is better to multiply first and divide afterward, to avoid troublesome frac- tions. (A description of the planimeter and full directions for its use on indicator diagrams are given in Chapter VII, Part II, and Chapters X and XI, Part III.)

Fig. 11 illustrates two diagrams divided first into ten equal spaces, and then each end space subdivided so as to more accurately measure those parts of each in which the greatest irreg- ularities occur. Observe that the pressures or heights of the subdivisions of each end space are measured, and the sum of these measure- ments divided by 2 to get the mean pressure or height of that one of the ten spaces.

The pressures of Diagram No. 1, as meas- ured by the scale, are set in a column on the left,

STEAM ENGINE.

93

DIAGRAM No. 1 Pressures.

DIAGRAM No. 2 Pressures.

FIG. 11.

HEIGHTS OF DIVISIONS MEASURED ON A STRIP OF PAPER. DIAGRAM No. 1. DIAGRAM No. 2.

10)11.95 in. Divide by 10 10)11.93 in.

1.195

50

M.E.P. 59.750

Multiply by proper scale.

1.193

50

M. E. P. 59.650

PLANIMETER MEASUREMENTS.

DIAGRAM No. 1. DIAGRAM No. 2.

Square inches, 4.42 Square inches, 4.46

Length, 3.72 Length, 3.73

Average height, 1.188 Average height, 1.195

M. E. P. 59.4 Ibs. M. E. P. 59.75 Ibs.

94 INDICATING THE

while those of No. 2 are set in a column on the right. The sum of each column divided by 10 gives the M. E. P. of that diagram.

The heights of Diagram No. 1, marked off on a slip of paper continuously, measure 11.93 inches, while those of No. 2 measure 11.95 inches; these quantities, divided by 10 and mul- tiplied by 50, give the M. E. P. of each diagram respectively, and if accurately measured, will be the same as found by the scale.

These diagrams, when measured by the planimeter, give results which are substantially the same as found by the approximate methods. These results are given at the bottom of page 93 with Fig. 11.

Having now obtained, by one of the several methods given above, our three factors men- tioned at the beginning of this chapter, viz.:

a = mean net area of piston in square inches.

5 = mean speed of piston in feet per minute.

p = mean effective pressure in pounds on each square inch of the piston — the product of their continued multiplication will give the indi- cated power of the engine in foot-pounds per minute; and this product divided by 33,000, which is the conventional number of foot-pounds in one horse power, will give a quotient equal to the indicated power of the engine in indicated horse power, commonly designated by the initial letters I. H. P.

Thus : I. H. P. = ^X_£X/ or asP 33,000 33.. 000

When there are a number of diagrams taken from the same engine to be worked up, the cal- culations may be simplified by multiplying the

STEAM ENGINE. 95

area of the piston by twice the length of the stroke, and dividing- the result by 33,000. This gives the "constant of the engine," that is, the power that would be developed at one revolution per minute with one pound mean effective press- ure. Multiply this constant by the number of revolutions per minute, and then by the mean effective pressure, and the product will be the I. H. P.

If the number of revolutions is the same for several diagrams, as is frequently the case with stationary engines, the calculation may be still further simplified by multiplying1 the "constant of the engine" by the number of revolutions per minute. This will give the "horse power constant, " or the horse power developed per pound M. YJ. P. Multiply the horse power constant by the M. E. P., and the product will be the indicated horse power (I. H. P.).

96 INDICATING THK

CHAPTER VI.

THE HYPERBOLIC CURVE.

This curve is frequently applied to indicator diagrams for the purpose of comparing- it with the expansion curve as drawn by the indicator, and if it coincides very nearly, this fact may generally be taken as evidence tending- to show that the steam and exhaust valves of the engine are properly closed and the piston tight.

Without going into any discussion regarding condensation and re-evaporation in steam engine cylinders, it is a well known fact that indicator diagrams, taken from large engines, properly made and in good order, show expansion curves which are close approximations to the hyperbola.

Before this curve can be drawn, it is neces- sary to ascertain the capacity of the clearance or waste room; that is, all the space between the cylinder heads and the piston at each dead cen- ter, including the counterbore and the ports up to the face of the closed valves.

There are several ways of finding this: One, by direct calculation from sectional drawings, when accurate drawings can be obtained; another, by putting the engine at dead center with valves closed, and then filling the clearance space with water, which has been carefully weighed in a convenient vessel, then weighing what is left; and the difference between the weight of the whole and the remainder is the weight of water required to fill the clearance space. From this the number of cubic inches

STKAM KNGINE. 97

occupied by the water may be computed. At ordinary temperatures (60° to 75° F.), for all practical purposes, we may call the weight of one cubic inch of water 0.036 pounds, and 27.8 cubic inches of water equal to one pound. Then the number of pounds of water, divided by 0.036 or multiplied by 27.8, will give the number of cubic inches. If accurate scales for weig-hing- the water are not at hand, it can be carefully measured in a quart or pint measure, and the number of cubic inches found directly. A g-allon contains 231 cubic inches, a quart 57.75 and a pint 28.875 cubic inches.

The volume of the clearance will rarely be alike at the two ends of the cylinder, therefore the number of cubic inches in the clearance at each end must be divided by the net area of the piston at its own end; that is, the number of cubic inches in the clearance at the end nearest the crank must be divided by the number of square inches in the cross-section of the cyl- inder, less the number of square inches in the cross-section of the piston-rod; and the number of cubic inches in the clearance at the end farthest from the crank must be divided by the number of square inches in the cross-section of the cylinder. The quotient in each case will be the leng-th of clearance at the respective ends of the cylinder, expressed in inches.

It is convenient to have the leng-th of the clearance expressed as a fraction of the piston displacement or stroke of the piston. To ob- tain this fraction, divide the number of cubic inches in volume of clearance by the number of cubic inches in the volume swept through by the

98 INDICATING THE

piston at each end separately, taking* care to allow for the volume occupied at one end by the piston rod, and the quotient will be the decimal fraction that the clearance space is of the volume swept throug-h by the piston. In this instance (Fig-. 12) it is found to be .16 inches.

Fig1. 12 illustrates a g"ood method for locating- points in the hyperbola throug-h which the curve may be drawn.

First, draw the zero line V, at the proper

Id -- v -- V- _^__ -- \i __ \f __ L _

U — - -- ^Length of2jta.gro.7n 3.90 FiG. 12.

distance, viz., 14-jV pounds by the scale below and parallel with the atmospheric line; next, draw the clearance line O, as computed, .16 of an inch from the end of the diagram; next, locate the point of cut-off X, and draw the perpen- dicular line number 3 through it; next, divide the space between this line and the clearance line into three equal parts; then, taking- one of these parts for a measure, point off, on the vacuum line, equal spaces toward the left hand until one or more falls beyond the end of the

STEAM ENGINE. 99

diagram as shown, and erect perpendicular lines from each point. These lines are called ordioates and numbered consecutively 1, 2, 3, 4, etc., beginning- with the one next to the clearance line. It is well to bear in mind the fact that vertical distance on a diagram represents press- ure, and horizontal distance volume.

In this case we have started the hyperbola from the point of cut-off X, and its course is indicated by the short lines drawn throug-h the ordinates a little above the actual curve, with their calculated pressures written above; the actual pressures of the expansion curve are written below it. The properties of the hyper- bola are such, that if the distance of the point Jf from the clearance line O be multiplied by the heig-ht of X from the zero line V, the heig-ht of any other point in the curve can be found by dividing- this product by its distance from the clearance line. And on this principle we proceed to locate points on the ordinates throug-h which our hyperbola will run.

We find the pressure at the point of cut-off to be 121 pounds, with a volume which we call 3, because there are three spaces or volumes between it and the clearance line. Then, 121 X 3 = 363, which is our dividend for all the other volumes. Therefore the height at which the hyperbola will cut ordinate 4 will be determined by dividing- 363 by 4, which is 90.8 (it is un- necessary to carry the division beyond one deci- mal), and of ordinate 5, 72.6; of ordinate 6, 60.5; and so on to the end. At ordinate 12 we find that the hyperbolic and the actual curves practi- cally coincide. In like manner we may extend

100 INDICATING THE

the curve to the right: 363 -*- 2 = 181 pounds, which would be the pressure if the steam were compressed up to two volumes. If desired, the hyperbolic curve can be started just before the point of release, and projected in the op- posite direction by the same method.

Instead of using- figures, which stand for pressures or volumes of steam, to locate the hyperbola, as in this instance, the distances from the base and perpendicular lines of any point may be expressed in inches and decimal parts, with the same result.

A quick way to draw the hyperbola is to take the whole distance between ordinate 3 and the clearance line as a measure, and set off equal spaces to the left, as before directed. Then we would have but four ordinates, and would num- ber them as follows: 1 at 3d, 2 at 6th, 3 at 9th and 4 at 12th. At 1 we would have a pressure of 121 pounds; at 2, 121 pounds -*- 2 = 60.5; at 3, 121 pounds -*• 3 = 40; and at 4, 121 pounds •*• 4 = 30.

As a general rule, the near approximation of the expansion curve to the theoretical or hyper- bolic curve may be taken as evidence of good conditions, but should not be accepted for a cer- tainty, unless all the known facts and conditions tend in the same direction.

GEOMETRIC METHOD OF FINDING THE HYPERBOLA.

The hyperbola may be found by following the directions given below, in connection with Fig. 13. A is the atmospheric line; Zthe zero line, or line of no pressure; B the line of boiler pressure, and C the clearance line. Locate the

STEAM ENGINE.

101

first point in the hyperbola at the point of release, X, and draw the vertical line, X E. Then draw diagonal line EH; then, from X, draw horizontal

FIG. 13.

line 5 to its intersection with EH, through which draw vertical line, F O. Now, mark off points between 0 and E, as 1, 2, 3, 4— exact spacing is unnecessary — and from these points draw di- agonal lines to H, and vertical lines down to, or

^-^. <L'. ^S.r^_ne_ ,

FIG. 14.

a little below, the actual curve. Now, draw horizontal lines 6, 7, 8 and 9 from the points of intersection in the line F O, of the diagonal lines

102 INDICATING THE

H 4, HZ, H2 and 77 1, respectively; and the points where these lines cross the vertical lines, 1, 2, 3 and 4, in connection with points Jf and (9, are the points throug-h which the hyperbola should be drawn, as shown b^ the dotted curve.

ANOTHER METHOD OF FINDING THE HYPERBOLA.

Fig". 14, shown on preceding" pag-e, illustrates another method of finding- the hyperbola.

Through the point of release b draw any line, as a B, and make A B equal to a b. Then draw any other line, as cD, and make cd equal to A D ; then d will be a point in the hyperbola passing- from b to A, as shown by the dotted curve. By drawing- a number of lines throug-h A and fol- lowing- the same method, we can find as many points in the hyperbola.

STKAM ENGINE. 103

CHAPTER VII.

AMSLER'S POLAR PLANIMETER, WITH DIRECTIONS

FOR USING IT ON INDICATOR DIAGRAMS. Fig-. 15 represents the No. 1 planimeter. It is the simplest form of the instrument, having but one wheel, and is designed to measure areas in square inches and decimals of a square inch. The figures on the roller wheel D repre- sent units, the graduations on the wheel repre- sent tenths, and the vernier gives the hundredths.

FIG. 15.

Directions for Measuring an Indicator Dia- gram with a No. i Planimeter. — Care should be taken to have a flat, even, unglazed surface for the roller wheel to travel upon. A sheet of dull finished cardboard serves the purpose very well.

Set the weight in position on the pivot end of the bar P, and after placing the instrument and the diagram in about the position shown in the cut (Fig. 16), press down the needle point so that it will hold its place; set the tracer point at any given point in the outline of the diagram, as at jF, and adjust the roller wheel to zero. Now follow the outline of the diagram carefully with the tracer point, moving it in the direction indi- cated by the arrow, or that of the hands of a

104

INDICATING THE

watch, until it returns to the point of beginning-. The result may then be read as follows: Suppose we find that the largest figure on the roller wheel D that has passed by zero on the vernier E, to be 2 (units), and the number of gradua- tions that have also passed zero on the vernier to be 4 (tenths), and the number of the graduation on the vernier which exactlv coincides with a

FIG. 16.

graduation on the wheel to be 8 (hundredths), then we have 2.48 square inches as the area of the diagram. Divide this by the length of the diagram, which we will call 3 inches, and we have .8266 inches as the average height of the diagram. Multiply this by the scale of the spring used in taking the diagram, which in this case is 40, and we Have 33.06 pounds as the mean effect- ive pressure per square inch on the piston of the engine.

STEAM ENGINE. 105

When there is a loop in the diagram (see Fig-. 10), caused by the steam expanding below the back pressure line when the engine is non-con- densing-, its outline should be traced in the same way as directed for a plain diagram, as the prin- ciple on which the planimeter works is such that the area of the loop will be subtracted from the main part of the diagram, and the reading of the instrument when the measurement is completed will be the correct net area sought.

When one has become familiar with the use of the planimeter it is not necessary always to set the wheels at zero, as required in the forego- ing directions, but their reading as they stand just before beginning to trace a diagram may be noted down, and this quantity subtracted from the reading when the tracing is completed. The difference between the two readings is the area sought.

The use of Amsler's Polar planimeter in the measurement of indicator diagrams enables one to measure ten cards with it in the time which would be required to measure one card by any other method, and it insures the utmost accu- racy in the work.

The planimeter is a precise and delicate in- strument, and should be handled and kept with great care, in order that it may be depended upon to give correct results. After using it should be wiped clean with a piece of soft chamois skin.

(8)

INDICATING

THE

REFRIGERATING MACHINE

PART III. CONSTRUCTION OF INDICATORS.

INTRODUCTION.

MANUFACTURERS' DESCRIPTION OF INDICATORS,

PLANIMETERS, REDUCING WHEELS AND COF- FIN *S AVERAGING INSTRUMENT, ETC.

The author is indebted to the various indi- cator manufacturers for the following" cuts and descriptions of their instruments. The indi- cators are described as "Steam Engine Indi- cators," but the descriptions, of course, apply equally as well to ammonia compressor indica- tors, the only difference being- that for com- pressor indicating- most manufacturers make an indicator of steel, aluminum or composition metal, to resist the action of ammonia. In all other particulars the indicators are the same.

I recommend that the reader send for the catalogues and price lists of these instruments.

The catalog-ues will be mailed free of charg-e, and many of them are quite valuable as treatises on indicator practice.

107

108 CONSTRUCTION OF INDICATORS.

CHAPTER I.

THE CROSBY INDICATOR.

The Crosby Indicator is designed and con- structed to meet the exacting- requirements of modern engineering-. During- the last few years, under the keen search and exhaustive tests of eminent engineers, the practice in this de- partment of science has underg-one important chang-es, tending- to establish more correct meth- ods and thereby to reach more accurate results; especially is this true in the use and scope of the indicator, so that the work done with this instru- ment in former times seems coarse and crude when compared with the more exact attainment of the present.

Educators in the scientific schools of both Europe and America have seen the importance of more exact knowledg-e and instruction in the technical sciences; and the great achievements of recent years in the construction of building's, ships, armaments and machines attest the thor- oughness with which research in these depart- ments has been prosecuted ; in none has there been greater progress made than in those of mechanical and steam engineering-.

A knowledg-e of these facts has kept the manu- facturer of the steam engine and ammonia com- pressor indicator on the alert. Within a recent time, the Crosby indicator has, without any great change in its outward appearance, received im- portant improvements. Slight changes in design, a more perfect mechanical construction due to the

CONSTRUCTION OF INDICATORS.

109

use of improved and specialized machinery, and a careful selection of metals for the different parts, have all contributed to this favorable result.

The movements of piston and pencil point are perfectly parallel; the movement of the pencil point is also exactly parallel with the axis of the drum.

FIG. 1.

The rating- of the springs by the newly con- structed testing- apparatus, which embodies all the valuable aids to exactness which have yet been discovered, is nearer perfection than could have been attained, or even expected, until within a very recent time.

DKSCRIPTION OF THE INDICATOR.

The illustration shows the design and

110 CONSTRUCTION OP^ INDICATORS.

arrangement of the parts of the Crosby steam engine indicator.

Part 4 is the cylinder proper, in which the movement of the piston takes place. It is made of a special alloy, exactly suited to the varying temperatures to which it is subjected, and se- cures to the piston the same freedom of move- ment with high pressure steam as with low ; and as its bottom end is free and out of contact with all other parts, its longitudinal expansion or con- traction is unimpeded, and no distortion can pos- sibly take place.

Between parts 4 and 5 is an annular chamber, which serves as a steam jacket; and being- open at the bottom, can hold no water, but will always be filled with steam of nearly the same tempera- ture as that in the cylinder.

The piston 8 is formed from a solid piece of the finest tool steel. Its shell is made as thin as possible consistent with proper streng-th. It is hardened to prevent any reduction of its area by wearing-, then ground and lapped to fit (to the ten-thousandth part of an inch) a cylindrical gauge of standard size. Shallow channels in its outer surface provide a steam packing, and the moisture and oil which they retain act as lubri- cants, and prevent undue leakage by the piston.

The piston rod 10 is of steel and is made hol- low for lightness. It is connected with the piston by a screw at its .lower end. When these parts are connected, be sure to screw the rod into the slotted socket as far as it will go; that is until the upper edge of the socket is set firmly against the bottom of the channel formed in the under side of the shoulder of the piston rod. This is

CONSTRUCTION OF INDICATORS. Ill

very important, as it insures a correct alinement of the parts and a free movement of the piston within the cylinder.

The swivel head 12 is screwed into the upper end of the piston rod, more or less according- to the required height of the atmospheric line on the diagram. Its head is pivoted to the piston rod link of the pencil mechanism.

The cap 2 rests on top of the cylinder, and holds the sleeve and all connected parts in place. The smooth portion of the cap which fits into the top of the cylinder serves as a guide by which all the moving parts are adjusted and kept in correct alinement.

The sleeve 3 surrounds the upper part of the cylinder and supports the pencil mechanism. The arm X is an integral part of it. The handle for adjusting the pencil point is threaded through the arm, and in contact with a stop screw in the plate may be delicately adjusted to the surface of the paper on the drum. It is made of hard wood in two sections ; the inner one may be used as a lock nut to maintain the adjustment.

The pencil mechanism is designed to afford sufficient strength and steadiness of movement, with the utmost lightness ; thereby eliminating, as far as possible, the effect of momentum, which is especially troublesome in high speed work. Its fundamental kinematic principle is that of the pantograph. The fulcrum of the mechanism as a whole, the point attached to the piston rod and the pencil point are always in a straight line. This gives to the pencil point a movement ex- actly parallel with that of the piston. The pencil lever, links and pins are all made of hardened

112 CONSTRUCTION OF INDICATORS.

steel; the latter — slightly tapering" — are ground and lapped to fit accurately, without perceptible friction or lost motion.

Springs. — In order to obtain a correct dia- gram, the height of the pencil of the indicator must exactly represent in pounds per square inch the pressure on the piston of the steam engine at every point of the stroke ; and the velocity of the surface of the drum must bear at every instant a constant ratio to the velocity of the piston. These two essen- tial conditions have been attained to a great degree of exactness in the Crosby indicator by a very ingenious construction and nice adaptation of both its piston and drum springs, and have proved satisfactory.

The piston spring is of unique and ingenious design, being made of a single piece of the finest spring steel wire, wound from the middle into a double coil, the spiral ends of which are screwed into a brass head having four radial wings with spirally drilled holes to receive and hold them securely in place. Ad j ustment is made by screw- ing them into the head more or less until exactly the right strength of spring is obtained, when they are there firmly fixed. This method of fastening and adjusting removes all danger of loosening coils, and obviates all necessity for grinding the wires.

The foot of the spring — in which lightness is of great importance, it being the part subject to the greatest movement — is a small steel bead,

CONSTRUCTION OF INDICATORS. 113

firmly "staked" on to the wire. This takes the place of the heavy brass foot used in other indi- cators, and reduces the inertia and momentum at this point to a minimum, whereby a great im- provement is effected. This bead has its bearing in the center of the piston, and in connection with the lower end of the piston rod and the upper end of the piston screw (both of which are concaved to fit) it forms a ball-and-socket joint which allows the spring- to yield to pressure from any direction without causing- the piston to bind in the cylinder.

The drum spring- in the Crosby indicator is a short spiral.

If the conditions under which the drum spring- operates be considered, it will readily be seen that at the beginning- of the stroke, when the cord hss all the resistance of the drum and spring- to over- come, the spring1 should offer less resistance than at any other time ; in the beginning- of the stroke in the opposite direction, however, when the spring has to overcome the inertia and friction of the drum, its energy or recoil should be greatest.

These conditions are fully met in the Crosby indicator; its drum spring being a short spiral, having no friction, a quick recoil, and being sci- entifically proportioned to the work it has to do.

The drum and its appurtenances, except the drum spring, are similar in design and function to like parts of other indicators, and need not be particularly described. All the moving parts are designed to secure sufficient strength with the utmost lightness, by which the effect of in- ertia and momentum is reduced to the least pos- sible amount.

114 CONSTRUCTION OF INDICATORS.

From the design of the Crosby indicator as above set forth — the conformation and purpose of its several parts — it will be seen that every opportunity to improve the instrument has been taken. Add to this the fact that only the most skillful workmen of long- training- in the art are employed, and that every part is made to a stand- ard size by modern specialized machinery, with tools perfectly adapted to their work, and it will be admitted that the proper means have been taken to produce a first-class indicator. We be- lieve this object has been accomplished.

All Crosby indicators are chang-eable from rig-fat hand to left hand instruments if occasion requires.

The Crosby indicator is ordinarily made with a drum one and one-half inches in diameter, this being- the correct size for hig-h speed work, and answering- equally well for low speeds. If, how- ever, the indicator is to be used only for low speeds, and a long-er diagram is preferred, it can be furnished with a 2-inch drum.

The Crosby indicator in a special design is made to indicate extremely hig-h pressures. In- struments of this desig-n have been used with perfect success in the testing- of ordnance and for other explosive effects.

When desired the Crosby indicator is made of steel, to resist the action of ammonia.

A detent attachment is furnished with the instrument when required.

Every part of the Crosby indicator is per- fectly adapted to its particular function, also to its relation to all the other parts, in size, pro- portion and material. Its small size and lig-ht

CONSTRUCTION OF INDICATORS. 115

weight serve to protect it from accident, and so contribute to its durability and to the facility with which it can be handled.

Full particulars for the proper care and hand- ling- of the Crosby indicator accompany each in- strument. They are manufactured only by the Crosby Steam Gage and Valve Co., Boston, Mass.

116

CONSTRUCTION OF INDICATORS.

CHAPTER II.

THE BACHELDER ADJUSTABLE SPRING INDICATOR.

Since the introduction of the Bachelder indi- cator to the pub- lic some years ago it has been mate- rially improved, both in design and detail of construc- tion.

The flat spring- is no longer an ex- periment, but an established suc- cess as to accu- racy and durabil-

FIG.

ity. The downward motion of the spring- being the same as the upward, a correct record is shown of a condensing or low pressure cylinder of a compound engine.

DESCRIPTION OF THE INDICATOR.

The special features of this instrument con- sist of the T shaped hollow case, and adjustable flat spring. The cylinder, being separate from the case proper, is screwed to the lower end, where it is held by a small set screw. By turn- ing this screw one-half of a turn the-cylinder can be unscrewed; then to remove the piston, take out the screw at the piston end of the spring, and at the connection with pencil lever. These are the only parts necessary to remove for cleaning. The flat steel spring works in the

CONSTRUCTION OF INDICATORS. 117

horizontal body of the case, one end being- rig-idly secured by means of a taper steel screw, and the other attached to the connecting- rod be- tween the piston and pencil lever. The chang-e of spring- is made by removing- the screw that connects it to the piston rod, and the one which holds it in the case. The rang-e of the hig-h pressure spring- is so great that a chang-e is only necessary when using- on a compound or triple

FiG. 4.

expansion eng-ine. Connection is made to the piston with a ball and socket joint. Access can be had to the piston for oiling- or removing-, by unscrewing- knurled cap on face of instrument.

A split bushing- in the case is provided with a longitudinal recess for the reception of the spring-. In the upper side of the bushing- a hard- ened steel pin is inserted. The lower side of the case has a longitudinal slot, through which a set screw passes and throug-h the lower side of the

118 CONSTRUCTION OF INDICATORS.

bushing, directly opposite the steel pin, so that when the screw is tightened, the spring is held rigidly between it and the steel pin. To change from one scale to another, loosen the set screw and slide the bushing along until the mark on projecting block is opposite the scale required, then tighten the screw. The scales are marked on the face of the case, the upper one being for high pressure, and the other for low pressure. The parallel motion is of the latest improved design, is entirely accurate and free from lost motion or friction. The height of atmospheric line is adjustable by means of a swivel in connect- ing rod near the pencil lever. With this brief description and a reference to the accompanying cuts, the general principle will be readily under- stood.

Each indicator is furnished with two flat springs, which are equivalent to eleven spiral springs.

The low pressure springs have the scales of 10, 15, 20 and 25. The high pressure springs have the scales of 30, 40, 50, 60, 70, 80 and 90, so that cards of proper height can be taken at any pressure up to 175 pounds. A special instru- ment for ammonia use, or for higher pressures than the above is furnished when required.

The Bachelder indicator is manufactured only by John S. Bushnell, successor to Thomp- son & Bushnell,- 120 and 122 Liberty street, New York City.

CONSTRUCTION OF INDICATORS. 119

CHAPTER III.

IMPROVED ROBERTSON-THOMPSON INDICATOR.

The improved Robertson-Thompson indica- tor, which has just been placed on the market, is unusually heavy, but as a result of most careful experiment this weight is so perfectly distribu- ted that the best results may be attained at speeds far in excess of any met with in actual practice. One of the most serious errors in or- dinary indicator work is caused by flexure of the arm which carries the drum, particularly when the cord is carried above or below the in- strument. In this manner an error of 10 per cent is easily possible, particularly if the instru- ment is being- used with a high pressure spring. For instance, with an 80 spring- it would re- quire a movement of but one-eightieth of an inch to show an error of one pound. In many cases weakness at this point will account for the curi- ous features often noticed at the junction of the admission and steam lines on the diagram. The drum carrying arm of the improved Robertson- Thompson indicator is so stiff that no error from this cause is possible.

DESCRIPTION OF THE INDICATOR.

The cylinder is steam jacketed, and by its construction the possibility of the piston being cramped as a result of external strains is pre- cluded. The area of this cylinder is exactly one-half inch, and each spring is suitable for twice the pressure stamped on it; for instance, a 60 spring may be used for a pressure of 120

120

CONSTRUCTION OF INDICATORS.

pounds or less. The coupling" is reamed to % -inch area, and with each instrument an extra ^-inch piston is furnished. With this piston each spring may be used for pressures four times as great as the number stampthereon, so that with a60spring- 240 pounds may be safely indicated. This extra piston is of special value for hydraulic and g-as en- g-ine work. The pistons are made of steel, but phosphor bronze will be substituted if preferred.

FIG. 5.

The piston spring's are standardized by the most approved testing- apparatus, in connection with a mercury column. To guarantee against press- ure above the piston, a large relief opening has been provided, the outlet being- a neat swivel elbow, by means of which the "blow" may be discharged in any direction, at the will of the operator. Each instrument is provided with a detent or stop motion.

In Fig. 6 a new device is shown for adjusting-

CONSTRUCTION OF INDICATORS.

121

the tension of the drum spring1. By rotating- the knurled head S, to the rig-lit the spring- may be tightened as much as de- sired, and securely held by pawl P; the ratchet wheel N is securely attached to the shaft by means of a left hand thread. FIG. 6. Thus the tendency of the drum

spring- is to tighten the ratchet nut more firmly. By pressing- the thumb into the recess in the spring- winder S, the pawl is released, when the tension maybe diminished to any desired amount. This ratchet wheel has sixteen teeth, which pro- vide for the adjustment of the spring to a nicety. Drum springs are of the clock type, but spiral form will be furnished if preferred. Cone bear- ings are provided to take up all wear of the drum spindle. The parallel movement is made of tool steel, highly polished and richly blued. All bearings are wide and perfectly fitted.

In Fig. 7 the pencil mechanism is shown in three positions, which will give a perfect idea of the manner in which an absolutely correct straight line is obtained. This movement forms a perfect pantograph, so that the pencil move- ment is exactly propor- tional to that of the pis- ton, theratiobeing5tol. All moving parts are worked down to the lightest weight consistent with durability. For comparison it may be stated that the drum weight is but one and one-fourth ounces, and the pencil lever twenty-five grains.

(9)

FIG.

122 CONSTRUCTION OF INDICATORS.

By special order, the instrument will be fitted with the improved Victor reducing- wheel, which comprises a patent cord feeding- device. The manufacturers are James L. Robertson & Sons, No. 204 Fulton street, New York city.

CONSTRUCTION OF INDICATORS. 123

CHAPTER IV.

THE BUFFALO INDICATOR.

The Buffalo indicator is of standard size, and well made throughout. It is handsome in design and finish, all working- parts being- accurately fitted and carefully tested. The working- parts are few, and of such light weight that a quick re- sponse to the steam pressure is always insured. A new style double coil spring of high tension is used, which insures correct diagrams. The piston is ^2-inch area, provided with water grooves. The piston rod is made of rVmch steel, hollow at the upper end, threaded to receive a swivel head (which per- mits of the adjustment of the pencil to suit weak or strong vacuum springs), and turned smaller at the lower, to reduce its weight.

The parallel motion is sms^*» pIG< 8. secured by a link attached to and governing the pencil lever direct. The screws of this link are made free from any appreciable loss motion, and will remain so indefinitely. It is made of "tool steel," and will trace a correct vertical line within its limit of three inches. The arm, link and up- rights are made of r\ X ^-inch steel, the uprights being held together by small bars /^-inch diam- eter, one-half inch long, the ends of which are turned smaller, and threaded to receive the ^-i

124

CONSTRUCTION OF INDICATORS.

hex nut, which fastens the uprights against the shoulder. The lower bar is centered at the proper angle to fit the pivot screws, and permit of very fine adjustment. Bearings of the link are one-fourth inch long. The entire movement is carefully blued. The movement of the pencil coincides with that of the piston at all times, and is acknowledged to be the most accurate made. The rosewood handle that swings the pencil

FIG. 9.

movement can be screwed in or out against the stop post so as to get the required pressure of lead or wire upon the card.

For ordinary use, drums 1.75 inches diam- eter, three and one-half inches high — two inches when specified — are furnished. They are made from special drawn telescope tubing, turned as thin as is consistent with ordinary usage, and supported at the top by a bearing one-half inch long. The barrel, which carries the drum, it will be noticed by reference to the cut, is very light,

CONSTRUCTION OF INDICATORS. 125

and is provided with adjustable cone bearings. The drum spring- is a flat coil of the clock pattern, and can be adjusted for any speed met in prac- tice, by unscrewing- the thumb screw, turning- to the quarter, then tighten as shown. The arm which carries the g-uide pulleys can be adjusted to allow the cord to run in any direction without the aid of carrying- pulleys. The drum cord will not climb from one coil to another, and can be adjusted to any angle by means of the g-uide pulleys.

The indicator is made almost entirely of brass, highly polished and nickeled; but for am- monia a special composition is used. Each in- dicator is sent out in a polished mahogany box, fitted with a metal plate, to which the indicator is attached by means of the coupling and plug.

126 CONSTRUCTION OF INDICATORS.

CHAPTER V.

AMERICAN THOMPSON INDICATOR.

The American Thompson improved indi- cator was patented by J. W. Thompson, August 31, 1875, and July 12, 1881.

The radical improvements, as made in the old style Thompson indicator, consist of lightening the moving parts, substituting steel screws in place of taper pins, using a very light steel link instead of a large brass one, reducing the weight of the pencil lever, also weight of squares on trunk of piston and lock nut on end of spindle, and increasing the bearing on connection of par- allel motion. By shortening the length and re- ducing the actual weight of the paper cylinder just one-half, and by shortening the bearing on spindle, also lowering the spring casing to a nearer plane to that in which the cord runs, we have reduced the momentum of the paper cylin- der to a very small amount. All of these im- provements have lessened the amount of friction, which was heretofore very small, but is now reduced to a minimum.

The parallel movement of pencil is secured by a link attached to and governing the lever direct. The pivots of this link are made free from any appreciable lost motion, and will remain so indefinitely; but if any such lost motion should exist, it will affect the integrity of the parallel movement only to an extent equal to it. The parallel movement will be affected only by the play in the pivots of the link, and not in any de- gree or manner by the play of any other parts.

CONSTRUCTION OF INDICATORS. 127

The force required to guide the lever in its parallel movement is received on the pivots of the link alone, where the friction it causes is practically inappreciable.

With the slot and roller device this guiding force is received on several rapidly moving- sur- faces, multiplied in amount by leverage. The same is true to a considerable extent of the plan of attaching the link to the connecting rod.

FIG. 10. . _v. .

The Paper Cylinder Movement. — It is so con- structed that the tension of the coiled drum spring within the paper cylinder can;be increased or decreased, for different speeds of engines. As little or as much of the spring can be taken up or let out as desired, thereby providing for fine adjustments.

For high speeds the instrument will give ac- curate results for all practical purposes, without

128

CONSTRUCTION OF INDICATORS.

any special adjustments further than to give suf- ficient tension to keep the cord taut at all points. When exceptionally accurate work is desired, the length of the diagram may be carefully measured, and compared with the length of a line traced on the paper when the engine is work- ing slowly. If the diagram is found to differ in

length from this line, vary the tension of the spring till they agree. The paper cylinder, or "drum," is now made with covered top.

The leading pul- ley for paper cylin- der, the latest im- provement in the American Thomp- son improved indica- tor, was patented FlG- n- June 26, 1883, and

consists (see Fig. 10) of a wheel which leads the cord through the hole, in contact with the scored wheel, over which the cord can be run to any possible angle, to connect with the motion wherever it may be, or of whatever kind.

The pulley works in a sleeve which rotates in the stand according to the adjustments required, and which is held in its position, where adjusted by the thumb screw, which acts as a binding screw working in the groove on the sleeve. By this it is held in any position that may be chosen, and yet is free to revolve the moment the bind- ing screw is loosened, without any possibility of

CONSTRUCTION OF INDICATORS. 129

interfering- with the motion by means of scarring the sleeve or disturbing- the particles of metal on surface. It also gives all the desired freedom of motion and facility of adjustment.

By means of the set screw, the stand which carries the wheel can be adjusted to run the cord to any possible angle within a rang-e of 360°.

In the double-pulley arrang-ement, as used in other indicators, the range of adjustment is limited, and in some cases the cord cannot be made to run in a number of certain directions, except in a grating1, roug-h and uneven manner.

In this improved swivel pulley the use of carrying pulleys is done away with, and from the fact that, no matter what the angle of deflection may be, or what direction it may be necessary to take the cord, it will work smoothly; for the pulley face and the face of the groove on the paper cylinder are always in the proper position, one with the other, to take the cord to the mo- tion, wherever that may be arranged.

In high speed, short stroke electric light en- gines great range of adjustment is very impor- tant; for considerable trouble is experienced sometimes upon engines running 350 and 360 revolutions per minute, in arranging the cords so as to use independent arcs, and in making such connections with reference to right lines, that no distortion of diagrams should be given.

It is provided with a "stop motion " (see Fig. 10), which is so arranged that the horn handle screw can be screwed up against the post or stop placed midway between paper cylinder and steam cylinder so as to regulate the pressure of pencil lead upon the paper.

130 CONSTRUCTION OF INDICATORS.

The best and finest quality of steel wire is used in making" our spring's; and they are all wound on a mandrel and tempered in the most careful manner by the oldest and most experi- enced workmen in the business.

All spring's are wound on mandrels from four to four and one-half threads to the inch, and thereby give more wire to each spring-, and a consequent less strain, than if wound, as in spring's of other indicators, on mandrels two to three threads to the inch.

Whatever grinding- is done to lig-hten a spring- amounts to very little; in fact, at the most it is

FIG. 12.

never ground to cause more than one to three pounds difference in 100 pounds; and, when the sensitiveness of the spring is considered, very little grinding will produce this result.

All springs made are scaled, providing for vacuum; and the capacity of any spring can be as- certained by the following general rule: Multiply scale of spring by 2/^, and subtract 15, and the result will be the limit of pounds steam pressure to which spring should be subjected. Example: 40-pound spring X 2% = 100 — 15 == 85 pounds pressure, capacity of a 40-pound spring.

To adapt the American Thompson improved indicator to all pressures, springs are made to any desired scale. The following are the most generally used : 8, 10, 12, 16, 20, 24, 30, 32, 40, 48,

CONSTRUCTION OF INDICATORS. 131

50, 56, 60, 64, 72, 80, 100. For pressures from 65 to 85 pounds, a 40-pound spring- is best adapted; for, as 40 pounds pressure on a 40-pound spring- will raise pencil one inch, 80 pounds pressure on the same spring- will raise pencil about two inches, which is the usual height of a diagram.

All the spring's are scaled providing- for vacuum, but close experiments have shown that, from the fact that spring's compress and elong-ate in unlike proportions, the regular press- ure springs vary about one pound in fifteen, or about 6^i per cent. A special vacuum spring is made with regular thread, scaled for vacuum only. .. The detent motion, as applied to the American Thompson indicator, consists of a pawl mounted on a stud, combined with a spring 'and ratchet, by the use of which the paper cylinder can be stopped and a change of cards made without unhooking or disconnecting the indicator cord.

By moving the pawl so as to catch in the teeth of the ratchet on base of paper cylinder, the latter is held stationary as the engine com- pletes its stroke. The cord, being entirely free, runs loosely with the motion of the engine, but the paper cylinder being stationary, the cards can be changed without the least disturbance of adjustments. By throwing the pawl out of the ratchet the paper cylinder is released, and im- mediately resumes its stroke with the engine, but care must be taken not to allow the paper cylinder, by force of its spring, to return to the stop with a thump; this can easily be done by simply holding the cord slightly with the thumb and finger until the beginning of the next stroke. This device obviates the change of adjustments,

132

CONSTRUCTION OF INDICATORS.

and is particularly valuable to amateurs and others not familiar with the use of the indicator. It is also valuable to users of the indicator on very quick running- electric lig-ht engines, and in all cases where the circumstances are such that the disconnection of the connecting- cord must cause the operator considerable trouble and the loss of valuable time.

All American Thompson improved indicators

are provided with a piston .798-inch di- ameter = %-mch area, which, with the 100-pound spring1, provides for indicat- ing pressure up to 250 pounds.

When pressure above that is to be indicated, an extra pistonis furnishedof .564-inch diameter^ ^-inch area, which, when substituted for the >^-inch area pis- ton, doubles the capacity of each spring-, thereby adapting- the indicator for indicating- pressures up to 500 pounds.

From the above it will be seen that when an indicator is furnished with the regular ^2 -inch area piston, and an extra %'-inch area piston in addition, the instrument can be used to indicate all pressures from 0 to 500 pounds.

This indicator is constructed of steel for ammonia compressor work.

FIG. 13.

CONSTRUCTION OF INDICATORS. 133

CHAPTER VI.

THE TABOR INDICATOR.

The special peculiarity of the Tabor indicator lies in the means employed to communicate a straig-ht line movement to the pencil. This and other features of the instrument are shown in the appended cuts, and these are so clear that little explanation is needed. A stationary plate containing* a curved slot is firmly secured in an upright position to the cover of the steam cylin- der. This slot serves as a guide and controls the motion of the pencil bar. The side of the pencil bar carries a roller which turns on a pin, and this fitted so as to roll freely from end to end of the slot with little lost motion. The cur ve of the the slot is so adjusted and the pin attached to such a point, that the end of the pencil bar, which carries the pencil, moves up and down in a straight line, when the roller is removed from one end of the slot to the other. The curve of the slot just compensates the tendency of the pencil point to move in a circular arc, and a straight-line motion results.

The pencil mechanism is carried by the cover of the outside cylinder. The cover proper is sta- tionary, but a nicely fitted swivel plate, which ex- tends over nearly the whole of the cover, is provid- ed, and to this plate the direct attachment of the pencilmechanismismade. By means of the swivel plate, the pencil mechanism may be turned so as to bring* the pencil into contact with the paper drum, as is done in the act of taking a diagram.

134

CONSTRUCTION OF INDICATORS.

The pencil mechanism is attached to the swivel by means of the vertical plate containing the slot, which has been referred to, and a small standard placed on the opposite side of the swivel for connecting- the back link. The slotted plate is backed by another plate of similar size, which serves to receive the pressure brought to bear on the pencil bar when taking- diagrams, and to keep the pencil bar in place. The pencil mechan- ism consists of three pieces: The pencil bar, the

FIG. 14.

back link and the piston rod link. The two links are parallel with each other in every position they may assume. The lower pivots of these links and the pencil point are always in the same straig-ht line. If an imaginary link be supposed to connect the two in such a manner as to be par- allel with the pencil bar, the combination would form an exact pantograph. The slot and roller serve the purpose of this imaginary link.

The connection between the piston and the

OF

CONSTRUCTION OF INDICATORS.

135

pencil mechanism is made by means of a steel piston rod. At the upper end, where it passes through the cover, it is hollow and has an outside diameter measuring- three-sixteenths of an inch. At the lower end it is solid and its diameter is reduced. It connects with the piston througti a ball and socket joint. The socket forms an in- dependent piece, which fits into a square hole in the center of the pis- ton, and is fastened by means of a central stem provided with a screw, which passes through the hole and receives a nut ap- plied from the under side. The nut has a flat sided head, so as to be readily oper- ated by the fingers. A number of shallow grooves are cut upon the outside of the piston, to serve as a so called water packing1.

Purchasers of indicators have many import- ant points to consider carefully before buying- an instrument of such precision as an indicator should be, to be reliable. One of the most im- portant features of an indicator is the parallel motion. It is one that has engrossed the atten- tion of leading- engineers and inventors for the past quarter of a century •: that the correctness of the parallel motion of the Tabor indicator is such that at all times and at every point on a diagram within the reacH of the pencil point, the

FIG. 15.

136 CONSTRUCTION OF INDICATORS.

extreme end of the pencil bar will record a ver- tical travel or movement of just five times that of the indicator piston.

The spring's used in the Tabor indicator are of the duplex type, being1 made of two spiral coils of wire with fitting's, as shown in the cut. The springs are so mounted that the points of connection of the two coils lie on opposite sides of the fitting. This arrangement equalizes the side strain on the spring, and keeps the piston central in the cylinder, avoiding the excessive friction caused by a single coil spring forcing the piston against the side of the cylinder. The thread by which the spring is attached is cut on the inside of the fitting, and suitable threaded projections on the under side of the cover and on the upper side of the piston, respectively, are provided for its attachment.

The springs are adjusted under steam press- ure, and are, consequently, correct only when used for steam engines. If required for water or other purposes, either special springs should be obtained that are adjusted with reference to the required use, or the springs should be tested at the time, and the actual scale of the spring deter- mined. It should be borne in mind that a spring becomes impaired by continued use, and its scale changes. For important work, therefore, the accuracy of the spring should always be tested by comparison on the spot with a reliable steam gauge, employing, as nearly as possible, the con- ditions under which the instrument was used. For steam work, they may be tested by attach- ing to the main steam pipe, for this purpose, a half-inch pipe fitted with a globe valve, a tee for

CONSTRUCTION OF INDICATORS.

137

the attachment of the indicator, another tee for the steam gauge, and finally a small drip valve. By keeping- the drip valve slightly open and regu- lating the globe valve, any desired pressures in the apparatus can be secured.

The maximum safe steam pressures above atmosphere, to which the various springs made for the indicator can be subjected, are given in the following table:

Scale of Spring.

Maximum Safe Pressure to Which a Spring- can be Subjected.

8

10

10

15

12

20

16

28

20

40

24

48

30

70

32

75

40

95

48

112

50

120

60

140

64

152

80

180

100

200

120

240

150

290

FIG. 16.

The paper drum turns on a vertical steel shaft, secured at the lower end to the frame of the indicator. The drum is supported at the bottom by a carriage, which has a long vertical bearing on the shaft. It is guided at the top by the same shaft, which is prolonged for this pur- pose, the drum being closed in at the top and provided with a central bearing. The drum is held in place by a close fit, in the usual manner, and is easily removed by the hand when desired. Stops are provided on the inside of the drum at the bottom, with openings in the outside of the

(10)

138 CONSTRUCTION OF INDICATORS.

carriage to correspond, so as to prevent the drum from slipping-. These are so placed that the position of the drum may be changed so as to take diagrams in the reverse position of the pencil mechanism, when so desired. The drum is made of thin brass tubing, so as to be ex- tremely light. Suitable strength is obtained by leaving a ring of thicker metal at the bottom and by employing the closed top. Steel clips are at- tached to the drum for holding the paper.

The drum carriage projects below the lower end of the drum, where it is provided with a groove for the reception of the driving cord. This groove has sufficient width for two com- plete turns of the cord. The drum spring, by which the backward movement of the drum is accomplished, consists of a flat spiral spring of the watch spring type, placed in a cavity under the drum carriage encircling the bearing. It is attached at one end to the frame below, and at the other end to the drum carriage. In its normal position the drum carriage is kept against a stop by means of the pull of the spring. The lower hub of the drum carriage rests directly on the spring case, while the opposite hub is in contact with a knurled thumb nut, screwed and pinned to the drum stud, in a position to just give a slight amount of end motion to the drum car- riage. This thumb nut also serves as a con- venient means of regulating the tension of the drum spring, as by loosening the nut that screws the spring case to the arm of the instrument, said thumb nut can be turned in either direction until the desired tension is obtained, and then again tightening the nut.

CONSTRUCTION OF INDICATORS. 139

A simple form of carrier pulley serves to operate the driving- cord from any direction. A single pulley is mounted within a circular per- pendicular plate, the center of which coincides with the center of the driving- cord. This center also coincides with the circumference of the pulley. The plate can be turned about its center so as to swing- the pulley into any desired ang-ular position, and thereby lead the cord off in any de- sired direction. The plate is held by a circular frame, which serves also as a clamp, and the pulley is fixed in position by the use of the same nut which secures the frame to the pulley arm.

Some of the prominent features in the design and construction of the Tabor indicator, which are noticeable to one handling the instrument, may be mentioned:

The instrument is attached by means of a coupling having but one thread. It is simple, like a common pipe coupling, and is operated by simply turning it in the proper direction, without exercising that care which the use of couplings having double threads requires.

The indicator cock has a stop which limits its range in either direction to full open or closed, and also has holes provided for the release of all steam that may remain between the indicator piston and cock after operating.

The pressure of the pencil on the paper drum is regulated by means of a screw, which passes through a projection on the slot plate, and strikes against a small stop provided for the purpose, which stands on the frame. This screw is operated by a handle, which is of sufficient size to be readily worked by the fingers, and which

140 CONSTRUCTION OF INDICATORS.

also serves as a handle for turning* the pencil mechanism back and forth, as is done in the act of taking- diagrams. The handle may be intro- duced and worked from either side, so as to use the pencil mechanism on either side of the paper drum.

The end of the pencil bar is shaped in the form of a thin tube for the reception of the pencil lead or metallic marking- point. The tube is split apart on the side and yields to the slig-ht press- ure required to introduce the pencil, which can be introduced from either side, so as to mark on either side of the paper drum desired.

The outside of the instrument in all its parts, excepting- the pencil bar and links composing the pencil mechanism, is nickel plated. The pencil mechanism is made of steel, hardened and drawn to a spring- temper, with blue finish.

Some of the dimensions of the parts in the instrument of standard size are as follows:

Diameter of piston 0.7978 inches.

Diameter of paper drum 2.063

Stroke of paper drum 5.5

Height of paper drum 4.

Number of times pencil mechanism

multiplies piston motion 5.

Rang-e of motion of pencil point 3.25

A result of the care in designing- and con- structing- these instruments is a reduction of friction to the least possible amount.

CONSTRUCTION OF INDICATORS. 141

CHAPTER VII.

THE IMPROVED VICTOR REDUCING WHEEL.

Recent improvements in the Victor reduc- ing wheel make it near absolute perfection. Every part is made of the material best suited to the work, and each joint is so admirably fitted that its lightness, accuracy and durability are only equaled by the convenience and facility with which it may be applied to any indicator, stroke or speed. It has no gears, therefore no grating- action. The cord wheel revolves on a polished spindle. The wheel is stationary, and the guide pulley is moved across its face a dis- tance equal to the thickness of the cord for each revolution, so that the cord will wind evenly, coil to coil, no matter in what direction it is led.

The improved Victor aluminum reducing wheel is made in two patterns, large and small. The only difference in these patterns lies in the diameter of the main cord wheel. The large pattern is especially intended for strokes of four feet and over, and will give perfect satisfaction on strokes of eight feet. There are several in use on high speed engines, but for this work the smaller size is recommended, and guaranteed to operate perfectly to any speed met with in practice.

Both patterns are carried in stock, with special arms D, Fig. 17, to fit all makes of indicators.

A feature of the Victor wheel is its extreme simplicity, and the facility with which it may be taken apart for cleaning and replacing springs.

142 CONSTRUCTION OF INDICATORS.

By actual timing- the instrument has been taken apart, a spring- replaced and assembled, ready for use in three minutes.

One of the most important features in a re- ducing- wheel is smooth running-. In fact, with- out it an accurate diagram cannot be secured. After many experiments the arrangement em- ployed in the improved Victor, a heavy, braided linen cord, which connects the small pulley E to the spring- case F, Fig-. 17, was adopted.

FIG. 17.

This method transmits the power of the spring- without friction, and as the cord is always under a uniform tension, all stretch is soon elim- inated. When worn out it may be replaced in a moment and without cost.

The spring case, F^ is made of aluminum, and is deeply grooved, so that the intermediate cord can never ride, and is perfectly guided at all times.

The freedom from friction, which is one of the most pleasing and noticeable features of the Victor wheel, insures its operation with much

CONSTRUCTION OF INDICATORS. 143

less spring- tension than others, which means longer life of the spring-.

The cord wheel revolves on a polished steel spindle, so that a nice fit may be made and main- tained, even after years of ordinary use.

The improved Victor wheel is provided with bushings for all strokes. These bushings, B, are quickly changed.

It is manufactured by James L. Robertson & Son, 204 Fulton street, New York city.

144 CONSTRUCTION OF INDICATORS.

CHAPTER VIII.

THE IDEAL REDUCING WHEEL.

The object of the reducing" wheel is to reduce accurately the motion of an engine cross-head to that required for a paper drum of an indicator, and to give the required length of diagram regardless of the engine stroke. If either the indicator or reducing- motion is not correct, the cards are useless and deceptive, hence the first step toward obtaining- the true state of affairs in a steam cylinder is an indicator that will show both the true pressure, or vacuum, and a cor- rect reducing- motion by which diagrams can be taken, so that an intellig-ent engineer can inter-, pret them, adjust the valves and figure the power developed.

The Ideal reducing wheel is made of alumi- num, brass and steel, combining strength and lightness, two essential features, together with first-class workmanship.

The wheel or drum, from which the cord passes to the cross-head is only two and three- quarters inches in diameter, and is made of aluminum. The coil spring for the take-up is in a case two and one-quarter inches in diameter, and connected by a 3 to 1 gear with the cord wheel spindle, so that while the light alumi- num cord wheel makes three revolutions, the spring makes but one. The spring can be ad- justed to any desired tension, to keep the cord taut on return stroke. The cord wheel revolves on a steel screw, the thread of which is the same

CONSTRUCTION OF INDICATORS. 145

pitch as the cord, so that when the cord is drawn out the wheel travels as -it revolves. By this means the cord is wound smoothly on the drum and passes straight through the guide pulley.

To use the reducing wheel on the indicator, remove the carrier pulley from the indicator, and put the wheel on in place of it. Pass the drum cord around the small disk through the hole and under the holder, being careful to see that the cord is wound around the bushing or disk from the left, as shown in Fig. 18. Before attaching hook see that cord on the wheel and indicator is taut at shortest part of the stroke, and that it will

FIG. 18.

pull out a little further than the longest part of vStroke. The reducing wheel can be used in any place where it is most convenient, bearing in mind that the cord from it to the cross-head should run in a straight line. In unhooking the cord, allow it to return slowly until the stop reaches the guide pulley.

Bushings of various sizes are furnished so that cards can be taken from any length of stroke up to seventy-two inches.

Theldealreducingwheel is manufactured only by John S. Bushnell, successor to Thompson & Bushnell, 120-122 Liberty street, New York city.

146 CONSTRUCTION OF INDICATORS.

CHAPTER IX.

SARGENT'S ELECTRICAL ATTACHMENT FOR STEAM ENGINE INDICATORS.

In making- elaborate tests of power plants, it has heretofore been necessary to employ as many assistants as there were indicators used, but the difficulty of securing- simultaneous action on their part is so great that satisfactory work is rarely obtainable, and more certain means to that end are now considered necessary.

Mr. Frederick Sargent, M.E., invented and patented an electrical device applicable to an in- dicator, by means of which any number of in- struments can be operated and diagrams taken at the same instant of time, simply by closing an electric circuit.

Fig-. 19 shows a Crosby indicator fitted with a Sarg-ent electrical attachment.

For the purpose of illustrating- the manner of operating- the attachment, assume that it is desir- able to procure simultaneous diagrams from a compound eng-ine, taking- cards from the ends of each cylinder. Attach the indicators to the en- gine and arrange the drum motion in the usual manner. On each indicator secure the electrical attachment to its plate. Make the connections with the battery, having all of the several magnets and the circuit closer in series. Place the paper upon the drum and bring the pencil arm into such a position as will allow the latch to drop into the screw eye.

Press the armature firmly against the magnet

CONSTRUCTION OF INDICATORS.

147

and adjust the marking- point to the paper in the usual manner. The sleeve handle must be un- screwed enough to allow the full operation of the armature. The circuit should be closed and the armature tension spring's adjusted, so that the connected attachment will work simultaneously. Everything- should now be in readiness to take diagrams. Connect the drum motions, open the indicator cocks, and as soon as desirable close

FIG. 19.

the circuit, and instantly all of the pencils will be broug-ht ag-ainst the papers and will remain there as long- as the circuit is kept closed.

In order to put on new papers, diseng-ag-e the drum motions, lift the latch and swing- the pencil arm out of the way.

The amount of battery power required will vary with circumstances and will-rang-e from one to two or more cells of a No. 2 Sampson battery, or its equivalent.

148 CONSTRUCTION OF INDICATORS.

The battery for operating- the attachment is inclosed in a neat hardwood box with a suitable handle for carrying1 it, and is sealed so as to pre- vent slopping-. It is very compact and portable, being- at the same time extremely active, long- lived and especially adapted to open circuit work.

The connections to the indicator attachments can be made with the battery without opening the box, the binding- posts being- on the outside. This battery, with a quantity of suitable wire for making- connections, is furnished with the attachment. The Sarg-ent electrical attachment is manufactured by the Crosby Steam Gag-e and Valve Co., Boston, Mass.

CONSTRUCTION OF INDICATORS. 149

CHAPTER X.

AMSLER'S POLAR PLANIMETER, WITH DIRECTIONS FOR USING IT ON INDICATOR DIAGRAMS.

Fig-. 20 represents the No. 1 plani meter. It is the simplest form of the instrument, having but one wheel, and is designed to measure areas in square inches and decimals of a square inch. The figures on the roller wheel D represent units, the graduations on the wheel represent tenths, and the vernier gives the hundredths.

The use of Amsler's polar planimeter in the measurement of indicator diagrams enables one

- FIG. 20.

to measure ten cards with it in the time which would be required to measure one card by any other method, and it insures the utmost accuracy in the work.

The planimeter is a precise and delicate in- strument, and should be handled and kept with great care, in order that it may be depended upon to give correct results. After using, it should be wiped clean with a piece of soft chamois skin.

The Amsler polar planimeter is manufact- ured by the Crosby Steam Gage and Valve Co., Boston, Mass.

150 CONSTRUCTION OF INDICATORS.

CHAPTER XL

THE LIPPINCOTT PLANIMETER.

The accompanying engraving-, Fig. 21, repre- sents a new form of planimeter.

It will be noticed that the wheel has a knife edge, and is free to move on its shaft, so that there can be no slipping- on the surface upon which it moves, giving- the same results when used upon the roug-hest table as upon the finest paper.

As the rotary movement of this wheel does not register, it is apparent that the accuracy of

FIG. 21.

the instrument will not be affected by any re- duction of the diameter of the wheel or injury to the knife edge. This is one of the most im- portant points to be considered in the selection of a planimeter. It is evident, however, that this claim is only made possible by taking the reading from the hub and not from the edge of the wheel. The possibility of a vitiated reading

CONSTRUCTION OF INDICATORS, 151

on account of the knife edge coming* in contact with separate scale, is also avoided thereby.

With the Lippincott planimeter the sliding- is done entirely upon the shaft, and as this shaft is made of glass it is practically frictionless.

The pivot screw is made hollow, and by means of a small knob a sharp point may be pro- truded for convenience in setting- to the card leng-th, while a small spiral spring- normally holds it in a protected position after the setting- opera- tion has been completed.

It will thus be seen that any bending- in the tracer point would be compensated for in every setting-, and could therefore occasion no error. This is a most important improvement, and guarantees initial and continued accuracy.

Inside the glass shaft is placed the scale, which is printed upon specially prepared paper, so that the greatest contrast and legibility may be insured. The ends of this shaft are then hermetically sealed under a partial vacuum, so that the scale can never become discolored or affected by the atmosphere.

The plates employed in printing- these scales are engine divided and mathematically correct.

Three of these scale tubes are provided with the instrument, each containing- two. different graduations, so that the mean effective pressure may be read direct, without computation, for the following- indicator springs: 6, 8, 10, 12, 16, 20, 24, 30, 32, 40, 50, 60, 80, 100, 120 and 150. For instance, if it is required to ascertain the M. E. P. of a card taken with an 80 spring-, insert a tube containing a 40 scale, and mentally double the reading1; or if special accuracy is

152 CONSTRUCTION OF INDICATOKS.

desired, trace the diagram twice, without stop- ping, and the reading- will be correct for an 80- pound spring-.

The correct reading- for a 20 spring- may be had from a 40 scale also, and in like manner other scales may be used with different spring's, which is more desirable than to encumber the case with a number of useless scale tubes.

Any special graduation will be furnished to order.

To use the instrument, select a tube contain- ing a scale corresponding to spring used in tak- ing the card, and insert same in the clamp, as in Fig. 21, after which the clamp screw is to be tightened sufficiently to prevent the tube from being easily moved.

Loosen the set screw, and adjust the points to the exact length of the card. The set screw should then be firmly tightened, so that the tracer bar cannot be moved in the frame block.

Having fastened the card upon the table with thumb tacks, place the instrument with radial bar at right angles to the tracer bar. After this move the tracer point down to point 7\ The left hand edge of the wheel hub may then be set at zero, either by moving the radial point /? to the right or left, or by moving the wheel on the shaft. After the instrument is properly placed, the tracer point should trace the line of the diagram to the left, in the direction taken by the hands of a watch, noting carefully that the wheel does not strike at either end of the shaft in making the circuit.

If a reading is desired in square inches, use a 40 scale and set the points four inches apart.

CONSTRUCTION OF INDICATORS. 153

The points may also set five inches apart and a 50 scale used, or six inches and a 60 scale. The latter is preferable in taking- the area of large figures.

Use no oil on any part of the instrument, and keep the glass tube perfectly clean with tissue paper, or clean chamois skin. The wheel should slide with perfect freedom from one end of the tube to the other.

This instrument is packed in a fine morocco velvet lined case, with nickel trimming's, and every one is guaranteed perfectly accurate. It is manufactured by James L. Robertson & Sons, 204 Fulton street, New York city.

(ii)

154 CONSTRUCTION OF INDICATORS.

CHAPTER XII.

THE COFFIN AVERAGING INSTRUMENT FOR CALCU- LATING INDICATOR DIAGRAMS.

When the mean effective pressure on a large number of diagrams is desired, time and labor may be saved by the employment of an averaging instrument or planimeter, an instrument de- signed to measure the areas of irregular figures. It is operated by moving a tracer, with which it is fitted, over the line of the diagram, and it records the area upon a graduated wheel.

In using the Coffin averager, the grooved metal plate, /, is first connected to the board upon which the apparatus is mounted, in the position shown in the cut, being held in place by a thumb- screw applied from the back side. The indi- cator card is then placed under the clamps Cand K, which may be sprung away from the board a sufficient amount to allow the card to be intro- duced, and the card is moved toward the left into such a position that the atmospheric line is near to and parallel with the lower edge of the station- ary clamp, C, while the extreme left hand end of the diagram is even with the perpendicular edge of the clamp. The movable clamp, K, which is fastened at the bottom to a sliding plate, is then moved toward the left, till the vertical beveled edge just touches the extreme right hand end of the diagram. The diagram shown in the cut represents the proper location which should ex- ist when these preliminary adjustments have been completed. The slide at the bottom of

CONSTRUCTION OF INDICATORS.

155

clamp A'fits closely, so- that the application of a slig-ht pressure with the thumb or finger is re- quired to displace it.

FIG. 22.

The beam of the instrument is next placed on the board, with the pin at the lower end resting- in the groove, /, and the weig-ht, Q, applied to the top of the pin so as to keep it securely in place.

156 CONSTRUCTION OF INDICATORS.

The tracer, O, is moved to the right hand end of the diagram and set at the point D, on the line of the diagram, where the clamp K and the diagram touch each other. Here a slight indentation is made in the paper by pressing the finger on the top of the tracer, and this serves as a starting point. The graduated wheel is next turned so as to bring its zero mark to the zero mark on the vernier. The instrument is now ready for operation. The tracer, O, is carefully moved over the line of the diagram, in the direction of motion of the hands of a watch, and continued till a complete circuit is made and the tracer finally reaches the starting point, D. Keeping an eye on the wheel, the tracer is now moved upward by sliding it along the edge of the clamp K, until the reading on the wheel returns to zero. Another light indentation is made in the paper to mark the new position which the tracer occupies. This point is represented at A in the cut. The in- strument is now moved away, the clamp pushed back, and the distance between the two points, D and A, is measured by employing a scale corre- sponding to the number of the spring used in the indicator. The distance thus found is the mean effective pressure, expressed in pounds per square inch of piston.

The Coffin planimeter determines the desired result without computation, but it may be used also for determining the area inclosed- by the diagram. This area is given by the reading on the graduated wheel, when the circuit of the diagram has been made and the tracer reaches the starting point, D. The wheel has fifteen main divisions, each of which represents one

CONSTRUCTION OF INDICATORS. 157

square inch of area. Each division has five sub- divisions, each sub-division representing- one- fifth, or two-tenths, of a square inch of area. The vernier scale enables the sub-divisions to be read in fiftieths, each of these fiftieths, therefore, representing- two-one-hundredths of a square inch. Having- obtained the area in this manner, the mean effective pressure may be computed by dividing- the number of the spring- represent- ing-the pressure per inch in heig-ht by the leng-th of the diagram (inches) and multiplying the quotient by the area (square inches). In first placing- the indicator card under the clamps, care must be observed that the ends of the dia- gram set a little away from the edg-e of the clamp, so as to allow for one-half the diameter of the tracer, and to bring- the center of the tracer over the center of the line of the diagram.

PART IV. MISCELLANEOUS TABLES.

160

MISCELLANEOUS TABLES.

PROPERTIES OF SATURATED AMMONIA.

CALCULATED FROM THE ORIGINAL FORMULA OF PROF. DE VOLSON WOOD, BY GEORGE DAVIDSON, M.E.

Computed especially for and originally published in Ice and Refriger- ation for December, 1894.

Tempera-

Pressure,

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—40

420.66

1539.90

10.69

—4.01

579.67

24.388

.02348

.0410

42.589

—40

39

1

1584.43

11.00

—3.70

579.07

23.735

.02351

.0421

42.535

39

38

2

16! JO. 03

11.32

—3.38

578.42

23.102

.02354

.0433

42.483

38

87

3

1676.71

11.64

—3.06

577.88

22.488

.02357

.0444

42.427

37

36

4

1724.51

11.98

—2.72

577.27

21.895

.02359

.0457

42.391

36

-36

425.66

1773.43

12.31

—2.39

576.68

21.321

.02362

.0469

42.337

—35

34

6

18*3.50

12.66

-2,04

576.08

20.763

.02364

.0482

42.301

34

33

7

1874.73

13.02

-1.68

575.48

20.221

.02366

.0495

42.265

33

32

8

1927.17

13.38

-1.32

574.89

19.708

.02368

.0507

42.213

32

31

9

1980.78

13.75

—0.95

574.39

19.204

.02371

.0521

42.176

31

—30

430.66

2035.69

14.13

—0.57

573.69

18.693

.02374

.0535

42.123

—30

29

1

2091.83

14.53

—0.17

573,08

18.225

.02378

.0519

42.052

29

28

2

2149.23

14.92

+0.22

572.48

17.759

.02381

.0563

42.000

28

27

3

2207.94

15.33

+0.63

571.89

17.307

.02384

.0577

41.946

27

26

4

2267.97

15.76

+1.05

571.28

16.869

.02387

.0593

41.893

26

—25

435.66

2329.34

16.17

+1.47

570.68

16.446

.02389

.0608

41.858

-25

24

6

2392.09

16.61

1.91

570.08

16.034

.02392

.0624

41.806

24

23

7

2456.23

17.05

2.35

569.48

15.633

.02395

.0640

41.754

23

22

8

2520.46

17.60

2.8

568.88

15.252

.02398

.0656

41.701

22

21

9

2588.77

17.97

3.27

568.27

14.875

.02401

.0672

41.649

21

—20

440.66

2657.23

18.45

+3.75

567.67

14.507

.02403

.0689

41.615

-20

19

1

2727.17

18.94

4.24

567.06

14.153

.02406

.0706

41.563

19

18

2

2798.62

19.43

4.73

566.43

13.807

.02409

.0725

41.511

18

17

3

2871:61

19.94

5.24

565.85

13.475

.02411

.0742

41.480

17

16

4

2946.17

20.46

5.76

565.25

13.150

.02414

.0760

41.425

16

—15

445.66

3022.31

20.99

+6.29

564.64

12.834

.02417

.0779

41.374

—15

14

6

3100.07

21.53

6.83

564.04

12.527

.02420

.0798

41.322

14

13

7

3179.45

22.08

7.38

563.43

12.230

.02423

.0818

41.271

13

12

8

3260.52

22.64

7.94

568. -82

11.939

.02425

.0838

41.237

12

11

9

3343.29

23.22

8.52

562.21

11.659

.02428

41 186

11

—10

450.66

3427.75

23.80

+9.10

561.61

11.385

.02431

.0878

41.135

—10

9

1

3513.97

24.40

9.70

560.99

11.117

.02434

.0899

41.084

9

8

2

3601.97

25.01

10.31

560.39

10.860

.02437

.0921

41.034

8

7

3

3691.75

25.64

10,94

559.78

10.604

.02439

.0943

41.000

7

6

4

3783.37

26.27

11.57

559.17

10.362

.02442

.0965

40.950

6

—5

455.66

3876. &>

26.92

12.22

558.56

10.125

.02445

.0988

40.900

— 5

4

6

3972.62

27.59

+12.89

557.94

9.894

.02448

.1011

40.845

4

3

7

4069.48

28.26

13.56

557.33

9.669

.02451

.10H4

40.799

3

2

8

4168.70

28.95

14.25

556.73

9.449

02454

.1058

40.749

2

1

4269.90

29.65

14.95

556.11

9.234

.02457

.1083

40.700

1

0

460.66

4373.10

30.37

+15.67

555.50

9.028

.02461

.1107

40.650

0

+1

1

4478.32

31 10

16.40

554.88

8.825

.02463

.1133

40.601

+ 1

2

4485.60

31.84

17.14

554.27

8.630

.0246H

.1159

40.551

2

3

'3

4694.96

32.60

17.90

553.65

8.436

.02469

.1186

40.502

jj

4

4

4806.46

33.38

18.68

553.04

8.250

.02472

.1212

40.453

4

* For values at temperatures higher than 100° F. see Wood's table on page 163.

MISCI<:LLAN?:OUS TABLES.

161

PROPERTIES OF SATURATED AMMONIA.

CALCULATED FROM THE ORIGINAL FORMULA OF PROF. DE

VOLSON WOOD, BY GEORGE DAVIDSON, M.E. Computed especially for and originally published in Ice and Refriger- ation for December, 1894.

Tempera- ture.

Pressure, Absolute.

Gauge Pressure, Pouud per Sq. Inch.

111

id*

iji

j15

!&*

W

p

n

m

Temperature. Degrees F. |l

EL.

Absolute. T,

f*

m

|

+5

465.66

4920.11

34.16

+19.46

552.43

8.070

02475

1240

40.404

+5

6

6

5035.95

4.97

20.27

651.81

7.892

02478

1267

40.355

6

7

7

5153.99

5.79

21.09

551.19

7.717

02480

1296

40.322

7

8

8

5274.28

6.63

21.93

550.58

7.553

02483

1324

40.274

8

9

9

5396.83

7.48

22.78

549.96

7.388

02486

1353

40.226

9

flO

70.66

5521.71

38.34

+23.64

549.35

7.229

02490

1383

40.160

+10

11

1

6649.48

9.23

24.53

548.73

7.075

02493

1413

40412

11

12

2

5778.50

4043

25.43

548.11

6.924

02496

1444

40.064

12

13

3

5910.52

1.04

26.34

547.49

6.786

02499

1474

40.016

13

14

4

6044.96

1.98

27.28

546.88

6.632

02502

1507

39.968

14

+15

475.66

6182.00

42.94

+28.24

546.26

6.491

02505

1541

39.920

+16

16

6

6321.24

3.90

29.20

545.63

6.355

02508

1573

39.872

16

17

7

6463.24

44.88

3048

545.01

6.222

02511

1607

39.872

17

18

8

6607.77

45.89

3149

544.39

6.093

02514

1641

<J9.777

18

19

9

6754.90

46.91

32.21

543.74

5.966

02517

4676

39.729

19

+20

480.66

6904.68

47.95

+33.25

543.15

5.843

02520

.1711

39.682

+20

21

1

7057.15

49.01

34.31

642.53

5.722

02523

1748

39.635

21

22

2

7211.33

50.09

35.39

541.90

5-. 605

02527

.1784

39.572

22

23

3

7370.27

51.18

36.48

641 38

5.488

.0^539

4822

39.541

23

4

7530.96

52.30

37.60

540.66

5.378

.02533

.1860

39.479

24

+26

485.66

7694.52

5343

+38.73

540.03

5.270

.02536

4897

39.432

+25

26

6

7860.89

54.59

39.89

539.41

5.163

.02539

493;

39.386

26 ,

27

7-

8030-16

55.76

41.06

538.78

6.068

.02542

4977

39.339

27 J

88

8

8202.38

66.96

42.26

538.16

4.960

.02545

.2016

39.292

28

29

9

8377-56

5847

43.47

537.63

4.858

.02548

.2059

39.246

29

+30

490.66

8555.74

59.42

+44.72

536.91

4.763

.02551

.2099

39.200

+30

31

1

8736.96

60.67

45.97

536.28

4.668

.02554

.2142

39415

31

32

2

8921.26

61.95

47.25

535.66

4.577

.02557

.2185

39408

32

33

3

9108.71

63.25

48.55

535.03

4.486

.02561

.2229

39.047

33

34

4

9299.32

64.58

49.88

534.40

4.400

.02664

.2273

39.001

34

+35

495.66

9493.07

65.92

+51.22

533.78

4.314

-.02568

.2318

38.940

+35

36

6

9690.04

67.29

52.59

633.13

4.234

.02571

.2362

38.894

36

37

7

9890. 75

68.68

53.98

532,52

4.157

.02574

.2413

38.850

37

38

8

10093.91

70.09

55.39

531.89

4 O68

.02578

.245!-

38.789

38

39

9

10300.88

71.53

56.83

531.26

3.989

02582

.2507

38.729

39

+40

500.66

10511.16

72.99

+68.29

530.63

3 915

.02586

.2554

38 684

+40

41

1

10724.95

74.48

59.78

529.99

3.839

.02588

.2606

38.639

41

42

2

10942.18

75.99

61.29

529.36

3.766

.02591

.2655

3S.595

42

43

3

11162.93

77.52

62.82

528.73

3.695

.02594

.2706

38.550

43

44

4

11387.21

79.08

64.38

528.10

3.627

.03597

.2757

33.499

4<J

+45

505.66

11615.12

80.66

+65.96

527.47

3 559

.0260(

.2809

38 461

+45

46

6

11846.64

82.27

67.5'i

526.83

3 493

02603

286*

38 41"

46

47

12081 80

83.90

69.20

526.20

3.428

.02606

.291"

38.373

47

41

8

12320.71

85.56

70.8fi

52557

3.362

.0^609

.2974

38.328

48

49

9

12563.36

87.2o

72.56

524 93

3 303

.02612

.302~

38.284

49

4-50

510.66

12809.91

.88.96

+74.26

524 3(

3.242

.02616

.3084

38.22h

4-50

"' 5

1

13U80.21

90.7

76 OC

r>23 6h

3.182

.02620

.3143

38 167

51

52

2

13314.43

92.4

77 7f

>23 03

3 124

02623

3201

3« 124

52

63

8

13572.52

94 2

79.55,522.39

3 069

0262fi

.3258

3* 080

53

54

4

13834.6

96.0

81.3?|521.7fi

3.012

.0262S

.3220

38 037

54

162

MISCELLANEOUS TABLES.

PROPERTIES OF SATURATED AMMONIA.

CALCULATED FROM THE ORIGINAL FORMULA OF PROF. DE VOLSON WOOD, BY GEORGE DAVIDSON, M.E.

Computed especially for and originally published in Ice and Refriger- ation for December, 1894.

Tempera-

Pressure,

g a>

g*3

5

Si

£S

-»$

ture.

Absolute.

*™

||

M

JP.£

2p

"j </3 *J

' 8?

hi

®t

»"§

O Q<

^EH^

$£

** D+^

>a3

'-'•ac .^_ c o

P

*~ '

CO

9

i

!*

|l

%*

*"•% .

**J

la*

M

!r

||s

&

f

1

|*

£

Ill

o

p

11 1

in

III

°S.5w>

Stt

+65

515.66

14100.74

97.92

+83.22

521.12

2.958

.02632

3380

37.994

+55

6«

6

14370.92

99.80

85.10

520.48

2.905

.02630

.344237.936

rxj

57

7

14645.18

101.70

87.00

519.84

2.853

.02639

.3505

37.893

57

58

8

14923.98

103.64

88.94

519.20

2.802

.02643

. 3568

07.835

59

9

15206.28

105.60

90.90

618.57

2.753

.02646

.3632

37.793

59

+60

520.66

15493.09

107.59

+92.89

517.93

2.705

.02651

.3697

37.736

+60

61

1

15784.23

109.61

94.91

517.29

2.658

.02654

.3762

37.678

61

62

2

16079.67

111.66

96.96

516.65

2.610

.02C58

.3831

37.622

62

63

3

16379.51

113.75

99.05

516.01

2.565

.02661

.3898

37.579

63

64

4

16683.76

115.86

101.16

515.37

2.520

.02665

.39(58

37.523

64

+65

525.66

16992.50

118.03

+103.33

514.73

2.476

.02668

.4039

37.481

+65

66

6

17305.70

120. 18

105.48

514.09

2.433

.026711.4110

37.43M

67

7

17623.45

122.38

107.68

513.45

2.389

.02675.4189

37.383

67

68

8

17946.89

124.62

109.92

512.81

2.351

.02678

.4254

37.341

(is

69

9

18272.81

126.89

112.19

512.16

2.310

.02682

.4329

37.285

69

+70

530.66

18604.53

129.19

+114.49

511.52

2.272

.02686

.4401

37.231

+70

71

1

18941.00

131.54

116.8*

510.87

2.233

.02689

.4479

37.188

71

72

2

19282.21

133.90

119.20

510.22

2.194

.02693

.4558

37.133

72

73

3

19628.32

136.31

121.61

509.58

2.153

.02697

.4645

37.079

73

74

4

19979.22

138.74

124.04

508.93

2.122

.02700

.4712

37.037

74

+75

535.66

20335.16

141.22

+126. 52

508.29

2.087

.02703

.4791

36.995

+75

76

6

20696.00

143. 72

129.02

507.64

2.052

.027«

.4873

36.954

76

77

7

21061.85

146.26

131.56

506.99

2.017

.02710

.4957

36.900

77

78

8

21432.82

148.84

134.14

506.34

1.995

02714

.5012

36.845

78

79

9

21808.85

151.45

136.76

605.69

1.952

02717

.5123

36.805

79

+80

510-66

.32190.15

154.10

+139.40

505.05

1.921

02721

.5205

36.751

+80

81

1

22576.51

166.78

142.08

504.40

1.889

02725

.5294

36.696

81

82

2

22968 '.88

159.50

144.80

503.75

1.858

02728

.5382

36.657

82

83

3

23365.38

162.26

147.56

503.10

1.827

02732

.5473

36.603

K3

84

4

23767.81

165.05

150.35

502.45

1.799

02736

.5558

36.549

84

+85

545.66

24175.61

167.88

+153.18

501.81

1.770

02739

.5649

36.509

+85

86

6

24588.92

170.75

156.05

501.15

1.741

02743

.5744

36.456

86

87

7

25007.80

173.66

158.96

500.50

1.714

02747

.5834

36.407

87

88

8

25432.16

176.61

161.91

499.85

1.687

02751

.5927

36.350

88

89

9

25862.14

179.69

164.89

*99.20

1.660

02754

.6024

36.311

89

+90

550.66

26297.88

182.62

+167.92

498.55

1.634

02758

.6120

36.258

+90

91

26739.88

185.69

170-99

97.89

1.608

02761

.6219

86.219

91

92

2

27186.56

188.79

174.09

497.24

1.5H3

02765

.6317

36.166

92

93

3

27639.43

191.94

177.24

496.59

1 .558

.02769

.6418

35.114

93

04

4

28098.26

195 13

180.43

95.94

1.534

.02772

6518

36.075

94

+95

555.66

28563.00

198. 35

+ 183. (15

95". 29

1.510

.02776

6622

36.025?

+95

96

6

29033.86

201.62

186.92

94.63

1.486

.02780

6729

35 971

97

f

29510.69

204.94

190.24

93.97

1.463

02784

6835

55.919

97

98

8

9993.52

208.29

193.59

93.32

1.442

.02787

6934

35.881

98

99

9

{0482.52

211.68

196.98

92.66

419

.02791

7047

35.829

99"

MOO

560.60

W977.78

215.12

+200.42

92.01

.398

.02795

7153

35.778

+ 100

MISCELLANEOUS TABLES.

163

WOOD'S TABLE OF PROPERTIES OF SATUR- ATED VAPOR OF AMMONIA.

Temperature

Pressure

i '

==

o

•o

W go

Absolute.

If —

tJ 2

* CD

ar-

\-

•X* '"D

£

S

||

I!

II

«H<5

S'l

51

* .

f*

2

£ h

£

k

*^g

f|

"3 "5

£s

* °j0

ow

•3

o|

§

a

a

ft

® (3

2a>

S*^

a~

^ *

I

I

2-

.s

1=

"*X3

ca

ll

ii

So

Q

^

H

i_3

tf

i

>•

t>

?

— 40

420.66

1540.9

10.69

579.67

48.23

531.44

24.37

.0234

0410

— 35

425.66

1773.6

12 31

576.69

48.48

528.21

21.29

.0236

.0467

— 30

430.66

2035.8

14.13

573.69

48.77

524.92

18.66

.0237

0535

- 25

435.66

2329.5

16.17

570.68

49 06

521.62

16.41

.0238

.0609

-20

440.66

2657.5

18.45

567.67

49.38

518.29

14.48

.0240

.0690

— 15

445.66

8022.5

20.99

564.64

49.67

514 97

12.81

0242

.0779

— 10

450.66

3428.0

23.77

561.61

49.99

511.62

11.36

.0243

.0878

— 5

455.66

3877.2

26.93

558.56

50.31

508.25

10.12

.0244

.0988

0

460.66

4373.5

30.37

555.50

50.68

504.82

9.04

0246

.1109

+ 5

465.66

4920.5

34.17

552.43

50.84

501.59

8.06

0247

.1241

+ 10

470.66

5622.2

38.55

549.35

51.13

498.22

7.23

0249

.1384

+ 15

475.66

6182.4

42.93

546.26

61.33

494.93

9.49

.0250

.1540

+ 20

480.66

6905.3

47.95

543.15

51.61

491.54

5.84

.0252

.1712

+ 25

485.66

7695.2

53.43

540.03

51.80

488.23

5.26

.0253

.1901

+ 30

490.66

8556.6

59.41

536.92

52.01

484.91

4 75

.0254

.2106 '

+ 35

495.66

9493.9

65.93

533.78

52.22

481.56

4.31

.0256

.2320

+ 40

500.66

10512

73.00

530.63

52.42

478.21

3 91

.0257

.2583

+ 45

505.66

11616

80.66

527.47

52.62

474.85

3.56

.0260

.2809

+ 50

510.66

12811

88.96

•524.30

52.82

471.48

3.25

.0260

.3109

+ 55

515.66

14102

97.93

521.12

53.01

468.11

2.96

.0260

.3379

+ 60

520.66

15494

107.60

517.93

53.21

464.72

2.70

.0265

.3704

+ 65

525.66

16998

118.03

514.73

53.38

461.35

2 48

.0266

.4034

+ 70

530.66

18605

129.21

511.52

53.57

457.85

2.27

.0268

.4405

+ 75

535.66

20336

141.25

608.29

53.76

454.53

2 08

.0270

.4808

+ FO

540.66

22192

154.11

504.66

53 96

450.70

1.91

.0272

.5262

+ 85

545.66

24178

167.86

501 81

54,15

447 66

1.77

.0273

.5649

+ 90

550.66

26300

182.8

498 ..11

54.28

443.83

1.64

.0274

.6098

+ 95

555.66

28565

198.37

495.29

54.41

440.88

1.51

.0277

6622

+100

560.66

30980

215.14

491.50

54.54

436.06

1.39

.0271)

.7194

+105

565.66

33550

232.98

488.72

54.67

434.08

1.289

.0281

.7757

+110

570.66

36284

251.97

485.42

54.78

430.64

1.203

.0283

.8312

+115

575.66

39188

272.14

482.41

54.91

427.40

1.121

.0285 .8912

+120

580.66

42267

293.49

478.79

55.03

423.75

1.041

.0287

.9608

+125 + 130

585.66 590.66

45528 48978

316.16 340.42

475.45 472.11

55.09 65.16

420.39 416.94

.9699 .9051

0289)1.0310 .0291 1.1048

+135

595.66

52626

365.16

468.75

55.22

413.53

.8457

.02931.1824

+140

600.66

56483

392.22

465.39

55.29

410.09

.7910

.02951.2642

+145

605.66

60550

420.49

462.01

65.34

406.67

.7408

.0297

1.349?

+160

610. 6tf

64833

450.20

458.62

55.39

402.23

.6946

.0299

1.4396

+155

615.66

69341

481.54

455.22

55.43

399 79

.6511

0302I1.535S

+ 160

620.66

71086

514.40

451.81

55.46

39R.H5

.6128

.0304

1.6318

+165

625.66

79071

549. 04 1 448.39

55.48 392.94 .5765

.0306

1.7344

Thfe critical pressure of ammonia is 115 atmospheres, the critical temperature at 130° F. (Dewar), critical volume .00482 (calculated).

164

MISCELLANEOUS TABLES.

TABLE OF AMMONIA GAS (SUPER-HEATED VAPOR). TEMPERATURE IN DEGREES F.

11

0

5

10

15

20

25

30

35

40

45

No. of Cu. Ft., v, Approximately Contained in ILb. of Gas.

15

18.81

19.05

19.20

19.48

19.68

19.87

20.08

20.2520.544

20.

16

17.56

17.85

18.09

18.24

18.43

18.52

18.81

18.9019.20

19.

17

16.60

16.70

16.96

17.08

17.28

17.48

17.66

17.8518.09

18.

18

15.54

15; 84

15.93

16.12

16.32

16.51

16.70

16,8917.08

17.

19

14.78

14.97

15.18

15.26

15.45

15.64

15,84

15.93

16.12

10.

20

14.01

14.25

14.40

H.49

14. 6g

14.88

14.97

15.16

15.36

15.

21

13.34

13.53

13.63

13.82

14.01

14.11

14.30

14.40jl4.59

14.

22

12.76

12.86

13.05

13.15

1334

13.44

13.63

13.7213.92

14.

23

12.19

12.28

12.48

12.57

12.76

12 86

13.05

13.1513.34

13.

1

24

11.71

11.80

11.90

12.09

12.19

12.38

12.48

12.57jl2.76

12.

25

11.23

11.34

11.42

11.61

11. Til 11.80

11.90

12 0912.19

12.

26

10.75

10.84

11.04

11.13

11.23

11.32

11.62

11.6111.71

11.

27

10.36

10.46

10.56

10.75

10.84

10.94

11.01

11.2311.32

11.

2s

9.98

10.08

10.17

10.36

10.46

.10.56

10.65

10.75

10.84

10.

29

9.60

9.69

9.79

9.98

10.08

10.17

10.27

10.36

10.46

10.

30

9.2120

9.30

10.46

9.60

9.69

9.79

9.98

10.08

10.17

10.

31

8.84

9.12

9.21

9.31

9.40

9.50

9.60

9.69

9.KO

9.

32

8.83

8.93

9.02

9.12

».21

9.31

9.40

9.50

9.

33

8.54

8.64

8.73

8.83

8.91

9.02

9.11

9.21

9.

34

8.25

9.35

8.49

8.54

8.64

8.73

8.83

8.92

9.

35

8.16

8.25

8.35

8.44

8.54

8.64

8.64

8.

33

•-.

7.87

7.96

8.06

8.16

8.2tf

8.35

8.44

8.

37

> 7.68

7.67

7.87

7.96

8.06

8.16

8.26

8.

38

7,48

7.58

7.68

7.77

7.77

7.8!

7.98

8.

3!)

7.39

7.48

7.48

7.58

7.68

7.77

7.

4(1

7.20

7.29

7.39

7.39

7.48

7.58

7.

41

7.00

7.10

7.20

7.20

7.29

7.39

7.

42

6.81

6.91

7.00

7.10

7.10

7.20

7'.

43

6.72

6.81

6.91

7.00

7.08

7.

44

6.52

6.62

6.72

6 81

6.91

45

6.43

6.52

6.62

6.62

6.72

6.

I

MISCELLANEOUS TABLES.

165

TABLE SHOWING REFRIGERATING EFFECT OF ONE CUBIC

FOOT OF AMMONIA GAS AT DIFFERENT CONDENSER AND SUCTION (BACK) PRESSURES IN B. T. UNITS.

o .

*•

Temperature of the Liquid in Degrees F.

•gfc

g s.S

65° 70° 75° 80° 85° 90° 95° 100° 105°

D (U

1J«?

-t-> be

W*1 a!

$ a a

|c

Ifj

Corresp'g. Condenser Pressure (gauge), Ibs. per sq. in.

8

H

°c^

103 115 127 139 153 168 184 200 218

G. Pres.

—27°

1

27.30

27.01

26.73

26.44

26.16

25.87

25.59

25.30

25.02

—20°

4

33.74

33.40

33.04

32.70

32.34

31.99

31.64

31.30

30.94-

—15°

6

36.36

3B.48

36.10

35.72

35.34

34.96

34.58

34.20

33.82

—10°

9

42.28

41.84

41.41

40.97

40.54

40.10

39.67

39.23

38.80

— 5°

13

48.31

47.81

47.32

46.82

46.33

45.83

45.34

44.84

44.35

0°

16

54.88

54.32

53.76

53.20

52.64

52.08

51.52

50.96

50 40

5°

20

61.50

60.87

60.25

59.62

59.00

58.37

57.75

57.12

56.60

10°

24

68.66

67.97

67.27

66.58

65.88

65.19

64.49

63.80

83.10

15°

28

75.88

75.12

74.35

73.59

72.82

72.06

71.29

70.53

69.76

20°

33

85.15

84.30

83.44

82.59

81.73

80.88

80.02

79.17

78.31

25°

39

95.50

94.54

93.59

92.63

91.68

90.72

89.97

88.81

87.86

30°

45

106.21

105.15

104.09

103.03

101.97

100.91

99.85

98.79

97.73

35°

51

115.69 114.54 123.39

112.24

111.09

109.94

108.79107.64

106.49

TABLE GIVING NUMBER OF CUBIC FEET OF GAS THAT MUST

BE PUMPED PER MINUTE AT DIFFERENT CONDENSER

AND SUCTION PRESSURES, TO PRODUCE ONE TON

OF REFRIGERATION IN TWENTY-FOUR HOURS.

§

Temperature of the Gas in Degrees F.

O .

v« ^ *

q P .5

65° 70° 75° 80° 85° 90° 95° 100° 105°

g|

II?

ft

f||

Corresp'g. Condenser Pressure (gauge;, Ibs. per sq. in.

1"

°lj

103 115 127 139 153 168 184 200 218

27°

G. Pres.

7.22

7.3

7.37

7.46

7.54

7.62

7.70

7.79

7.88

—20°

4

5.84

5.9

5.96

6.03

6.09

6.16

6.23

6.30

6.43

—15°

6

5.35

5.4

5.46

5.52

5.58

5.64

5.70

5.77

5.83

-10°

9

4.66

4.73

4.76

4.81

4.86

4.91

4.97

5.05

5.08

- 5°

13

4.09

4.12

4.17

4.21

4.25

4.30

4.35

4.40

4.44

0°

16

3.59

3.63

3.66

3.70

3.74

3.78

3.83

3.87

3.91

5°

20

3.20

3.24

3.27

3.30

3.34

3.38

3.41

3.45

3.49

10°

24

2.87

2.9

2.93

2.96

2 99

3.02

3.06

3.09

3.12

15°

28

2.59

2.61

2.65

2.68

2.71

2.73

2.76

2.80

2.82

20°

33

2.31

2.34

2.36

2.38

2.41

2.44

2.46

2.49

2.51

25°

39

2.06

2.08

2.10

2.12

2.15

2.17

2.20

2.22

2.24

30°

45

1.85

1.87

1.89

1.91

1.93

1.95

1.97

2.00

2.01

35°

51

1.70

1.72

1.74

1.76

1.77

1.79

1.81

1.83

1.85

166 MISCELLANEOUS TABLES.

ANHYDROUS AMMONIA.

Ammonia is a compound of one volume of nitrogen with three volumes of hydrogen, and is therefore represented by the chemical form- ula NH3. It contains by weight 82.35 per cent nitrogen and 17.65 per cent hydrogen. Its mole- cular weight is 17.

Ammonia is a colorless gas possessing a very characteristic pungent smell. It is much lighter than air, having a specific gravity (air 1) of 0.586, one liter of gas weighing, at the normal temper- ature and pressure, 0.76193 grams. By mechan- ical pressure and cooling, it is converted from a gaseous to a liquid state (liquid anhydrous am- monia) which boils under the ordinary atmos- pheric pressure at 28T60° below zero, or 240^° lower than the boiling point of water under the same conditions. One pound of the liquid at 32° will occupy 21.017 cubic feet of space when evaporated at the atmospheric pressure. The specific heat of ammonia gas, as determined by Regnault (capacity for heat), is 0.50836. Its latent heat of evaporation is about 560 thermal units at 32° Fahrenheit, at which temperature one pound of the liquid, evaporated under a pressure of fifteen pounds per square inch, will occupy twenty-one cubic feet.

TESTING ANHYDROUS AMMONIA.

Usually ammonia manufacturers sell their goods subject to the condition and agreement, on the part of the purchaser, that a sample be drawn from each cylinder upon arrival and sub- jected to a test before emptying the contents,

MISCELLANEOUS TABLES. 167

no reclamation being- allowed on account of de- ficiency in quality or strength after a cylinder has been emptied or partly emptied. Therefore it is important that the consumer satisfy him- self of the purity of the ammonia before drawing off the contents of the cylinder.

EVAPORATION TEST.

Any dealer in chemical supplies will furnish an 8-ounce, flat bottom, wide neck, Bohemian glass boiling- flask (in case of breakag-e it is well to have several of these). Fit in the neck a stopper having- a ^-inch vent hole punctured through for escape of the gas. Insert in this hole a short g-lass tube. Procure a piece of 3/8-inch iron pipe, threaded at one end; bend the pipe to such a shape that the threaded end can be connected with the cylinder valve; put the wrench on the valve of the cylinder and open it gently; allow a little of the ammonia gas to escape at first in order to purge the pipe and valve, then draw into the test flask from 2^ to 4 ounces of the liquid ammonia. When this is accomplished, remove the test flask at once, and insert in the neck the stopper with vent tube, then place it in such a position as will allow a small stream of water to flow over the sides of the flask. Under these conditions the ammonia will boil quickly and soon evaporate. Any residue remaining in the flask indicates impurities. Care is necessary in drawing off the sample, as a very little moisture in the test flask or in the pipe, or a brief exposure to the atmosphere, will at once affect it.

OF

168

MISCELLANEOUS TABLES.

COMPARISONS OF THERMOMETER SCALES, SHOWING RELATIVE INDICATIONS OF THE CELSIUS, FAHREN- HEIT AND REAUMUR THERMOMETER SCALES.

In the United States and England the Fahrenheit scale is generally used; in France and in all scientific investigations and treatises, the Celsius scale is uniformly used; and in Germany the Reaumur scale is the one generally adopted.

c.

F.

R.

C.

F.

R.

C.

F.

R.

100°

212.0°

80.0°

53°

127.4°

42.4°

6

42.8°

4.<S°

99

210.2

79.2

5'i

125.6

41.6

5 41.0

4.0

98

208.4

78.4

51

123.8

40.8

4

39.2

3.2

97

206.6

77.6

50

122.0

40.0

3

37.4

2.4

9i

204.8

76.8

49

120.2

39.2

2

35.6

lx.0

93

203.0

76.0

48

118.4

38.4

1

33.8

O.H

U

201.2

75.2

47

116.6

37.6

Zero

32.0

Zero

93

199.4

74.4

46

114.8

36.8

1

30.2

0.8

92

197.6

73.6

45

113.0

36.0

2

28.4

1.6

91

195.8

72.8

44

111.2

35.2

3

26.6

2.4

90

194.0

72.0

43

109.4

34.4

4

24.8

3.2

89

192.2

71.2

42

107-6

38.6

5

23.0

4.0

88

190.4

70.4

41

105.8

32.8

6

21.2

4.8

87

188.8

69.6

40

104.0

32.0

7

19.4

5.6

86

186.8

68.8

39

102.2

31.2

8

17.6

6.4

85

185.0

68.0

38

100.4

30.4

9

16.8

7.2

84

183.2

67.2

37

98.6

29.6

10

14.0

8.0

b3

181.4

66.4

36

«6.8

28.8

11

12 2

8.8

82

179.6

65.6

36

95.0

28.0

12

10.4

9.6

81

177.8

64.8

34

93.2

27.2

13

8.6

10.4

80

176.0

64.0

33

91.4

26.4

14

6.8

11.2

79

174.2

63.2

32

89.6

25.6

15

5.0

12.0

78

172.4

62.4

31

87.8

24.8

16

3.2

12.8

77

170.6

61.6

30

86.0

24.0

17

1.4

13.6

76

168.8

60.8

29

84.2

23.2 18

14.4

75

167.0

60.0

28

82.4

22.4 19

2.2

15.2

74

165.2

59.2

27

80.6

21.6 20

4.0

lfl.0

73

163.4

58.4

26

78.8

20.8 ! 21

5.8

16.8

72

161.6

57.6

25

77.0

20.0 ! 22

7.6

17.6

71

159.8

56.8

24

75.2

19.2 23

9.4

18.4

70

158.0

56.0

23

73.4

18.4 || 24

11.2

19.2

69

156.2

55.2

22

71.6

17.6 25

13.0

20.0

68

154.4

54.4

21

69.8

16.8 ! 26

14.8

20.8

67

152.6

53.6

20

68.0

16.0 i 27

16 6

21.6

66

ISO. 8

52.8

19

66 2

15.2 ! 28

18.4

22.4

65

149.0

52.0

18

64.4

14.4 | 29

20.2

23.2

64

147.2

51.2

17

62.6

13.6

30

22.0

24.0

63

146.4

50.4

16

60.8

12.8

81

23.8

24. 8

62

143.6

49.6

15

59.0

12.0

32

25.6

25.6

61

141.8

48.8

14

57.2

11.2 II 33

27.4

26.4

60

140.0

48.0

13

.55.4

10.4 i 34

29.2

27.2

59

138.2

47.2

12

53.6

9.6

35

31.0

28.0

58

136.4

46.4

11

51.8

8.8

36

32.8

28.8

57

134.3

45.6 li 10

50.0

8.0

37

34.6

29.6

56

132.8

44.8 9

48.2

7.2

38

36.4

30.4

55

131.0

44.0

8

46.4

6.4

39

38.2

31.2

54

129.2

43.2

7

44.6

5.8

40

40.0

32.0

MISCELLANEOUS TABLES.

169

MEAN PRESSURE OF DIAGRAM OF AMMONIA COMPRESSOR.

Reprinted from the Catalogue of the De La Vergne Refrigerating Machine Co.

Oi 4^ CO

Men CD

...

tO M M g 3!

OO5CO COO54^ to <W

? |

Condens pera

Condense]

m

to i— ' i— •

O O O

1 1 I 1 |l

MM tO g ^

enoen oeno S-™ ooo ooo pg.

er Tem- ture.

•Pressure.

4- 4- *- O CO en

— . _ —

-4— I OO

^. ^ _ _ __ _ — I O5 en 4^ tO M

05

L

en MO

bO 05 05

oooo

00004^

-4 CD OO 4^ ^1 4^

4* rfi. C5 O tO O5

'o

CO

— — ^'

-4 CO M

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Oi en 4^ 4^ 4^ 4^ h- ' O CD — 4 Oi CO

-4

'

£2£

CO O5 4*- 0-40

-4 Oi M CO CO CD

cc O5 en oo oo M

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to ro en

en en en 'en '4> ^4

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en en en en 45>. *>. en 4^ to o -4 05

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—4

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to to •— '

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O5 4i> CD tO *>• tO -4 O — 4 Ol O CO

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CD

M

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sbe§

00 05 *- 4^ O5 tO

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O5 O5 Oi M OO M tO tO CO O5 O5 M

1

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ajgg

00 OO -4 CO i— 00

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0000 00

O5 CO Oi

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O5 tO OO t— ' :•£• Oi M tO M 4^- O 4^

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p

CO CD CD 4- CO M

OC OO GO OO O5 tO

—4 —4 »*4 O5 O5 O5

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tO CD CD

CD —' CD M OO -4

O5 OO O O O CD I—1 4^ GO CO OO CD

I

00

(12)

170

MISCELLANEOUS TABLES.

PROPERTIES OF SATURATED STEAM,

Total pressure per square inch.

Temperature in Fahrenheit degrees.

Total heat, in Fahrenheit degrees, from water at 32° F.

Latent heat, Fahrenheit degrees.

Density, or weight of one cubic foot.

Volume of one pound of steam.

Relative vol- ume or cubic feet of steam from one cubic foot of water.

Lbs.

Fahr.

Fahr.

Fahr.

Lbs.

Cubic Feet

Rel. Vol.

1

102.1

1112.5

1042.9

.0030

330.36

20600

2

126.3

1119.7

1025.8

.0058

172.08

10730

3

141.6

1124.6

1015.0

.0085

117.52

7327

4

153.1

1128.1

1006.8

.0112

89.62

5589

5

162.3

1130.9

1000.3

.0138

72.66

4530

6

170.2

1133.3

994.7

.0168

61.21

3816

7

176.9

1135.3

990.0

.0189

52.94

3301

8

182.9

1137.2

985.7

.0214

46.69

2911

9

188.3

1138.8

981.9

.0239

41.79

2606

10

193.3

1140.3

978.4

.0264

37.84

2360

11

397.8

1141.7

975.2

.0289

34.63

2157

12

202.0

1143.0

972.2

.0314

31.88

1988

18

205.9

1144.2

969.4

.0338

29.57

1844

14

209.6

1145.3

966.8

.0362

27.61

1721

14.7

212.0

1146. 1

965.2

.0380

26.36

1642

15

213.1

1146.4

964.3

.0387

25.85

1611

16

216.3

1147.4

962.1

.0411

24.32

1516

J7

219.6

1148.3

959.8

.0435

22.96

1432

18

222.4

1149.2

957.7

.0459

21.78

1357

19

225.8

1150.1

955.7

.0483

20.70

1290

20

228.0

1150.9

952.8

.0507

19.72

1229

21

230.6

1151.7

951.3

.0531

18.84

1174

22

233.1

1152.5

949.9

.0555

18.03

1123

23

235.5

1153.2

948.5

.0580

17.26

1075

24

237.8

1153.9

946.9

.0601

16.64

1036

25

240.1

1154.6

945.3

.0625

15.99

996

26

242.3

1155.3

943.7

.0650

15.38

958

27

244.4

1155.8

942.2

.0673

14.86

926

28

246.4

1158.4

940.8

.0696

14.37

895

29

248.4

1157.1

939.4

.0719

13.90

866

30

250.4

1157.8

937.9

.0743

13.46

838

31

252.2

1158.4

936.7

.0766

13.05

813

32

254.1

1158.9

935.3

.0789

12.67

789

33

255.9

1159.6

934.0

.0812

12.31

767

34

257.6

1160.0

932.8

.0835

11. U7

74fl

35

259.3

1160.5

931.6

.0858

11.65

726

36

260.9

1161.0

930.5

.0881

11.34

707

37

262.6

1161.5

929.3

.0905

11.04

688

38

264.2

1162.0

928.2

.0929

10.76

671

39

265.8

1162.5

927.1

.0952

10.51

655

40

267.3

1162.9

926.0

.0974

10.27

640

41

268.7

1163.4

924.9

.0996

10.03

625

42

270.2

1163.8

923.9

.1020

9.81

611

43

271.6

1164.2

922.9

.1042

9.59

698

44

273.0

1164.6

921.9

.1065

9.39

585

45

274.4

1165.1

920.9

.1089

9.18

572

40

275.8

1165.5

919.9

.1111

9.00

561

47

277.1

1165.9

919.0

.1133

8.82

550

48

278.4

1166.3

918.1

.1156

8.65

539

49

279.7

1166.7

917.2

.1179

8.48

529

50

281.0

1167.1

916.3

.1202

8.31

518

51

282.3

1167.5

915.4

.1224

8.17

509

62

283.5

1167.9

914.5

.1246

8.04

500

53

284.7

1168.3

913.6

.1269

7.88

491

54

285.9

1168.6

912.8

.1291

7.74

482

55

287.1

1169.0

912.0

.1314

7.61

474

66

288.2

1169.3

911.2

.1336

7.48

466

MISCELLANKOUS TABLES.

171

PROPERTIES OF SATURATED STEAM.— CONT.

Total pressure per square inch, j

Temperature in Fahrenheit degrees.

Total heat, in Fahrenheit degrees, from water at 32° F.

Latent heat, Fahrenheit degrees.

i Density, or weight of one cubic foot.

Volume of one pound of steam.

Relative vol- ume or cubic feet of steam from one cubic foot of water.

Lbs.

Fahr.

Fahr.

Fahr.

Lbs.

Cubic Feet

Rel. Vol.

57

289.3

1169.7

910.4

.1364

7.38

458

68

290.4

1170.0

909.6

.1380

7.24

451

59

291.6

1170.4

908.8

.1403

7.12

444

60

292.7

1170.7

908.0

.1425

7.01

437

61

293.8

1171.1

907.2

.1447

6.90

430

62

204.3

1171.4

906.4

.1469

6.81

424

63

295.9

1171.7

905.6

.1493

6.70

417

64

296.9

1172.0

904.9

.1516

6.60

411

65

298.0

1172.3

904.2

.1538

6.49

405 -

66

299.0

1172.6

903.5

.1560

6.41

399

67

300.0

1172.9

902.8

.1583

6.32

393

68

300.9

1173.2

902.1

.1605

6.23

388

69

301.9

1173.5

901.4

.1627

6.15

383

70

302.9

1173.8

900.8

.1648

6.07

378

71

303.9

1174.1

900.3

.1670

5.99

373

72

304.8

1174.3

899.6

.1692

5.91

368

73

305.7

1174.6

898.9

.1714

5.83

363

74

306.6

1174.9

898.2

.1736

5.75

359

75

307.5

1175.2

897.5

.1759

5.68

353

76

308.4

1175.4

896.8

.1782

5.61

349

77

309.3

1175.7

896.1

.1804

5.54

345

78

310.2

1176.0

895.5

.1826

5.48

341

79

311.1

1176.3

894.9

.1848

5.41

337

80

312.0

1176.5

894.3

.1869

5.35

333

81

312.8

1176.8

893.7

.1891

5.29

329

82

313.6

1177.1

893.1

.1913

5.23

325

83

314.5

1177.4

892.5

.1935

5.17

321

84

315.3

1177.6

892.0

.1957

5.11

318

85

316.1

1177.9

891.4

.1980

5.05

314

86

316.9

1178.1

890.8

.2002

5.00

311

87

317.8

1178.4

890.2

.2024

4.94

308

88

318.6

1178.6

889.6

.2044

4.89

305

89

319.4

1178.9

889.0

.2067

4.84

301

90

320.2

1179.1

888.5

.2089

4.79

298

91

321.0

1179.3

887.9

.2111

4.74

295

92

321.7

1179.6

887.3

.2133

4.69

292

93

322.5

1179.8

886.8

.2155

4.64

289

94

323.3

1180.0

886 3

.2176

4.60

288

95

324.1

1180.3

886 8

.2198

4.56

283

96

324.8

1180.5

885.2

.2219

4.51

281

97

325.6

1180.8

884.6

.2241

4.46

278

98

326.3

1181.0

884.1

.2263

4.42

275

99

327.1

1181.2

883.6

.2285

4.37

272

100

327.9

1181.4

883 1

.2307

4.33

270

101

328.5

1181.6

882.6

.2329

4.29

267

102

329.1

1181.8

882 1

.2351

4.25

265

103

329.9

1182.0

881.6

.2373

4.21

262

104

330.6

1182.2

881 1

.2393

4.18

2«0

105

331.3

1182.4

880.7

.2414 ! 4.14

287

106

331.9

1182.6

880 2

.2435 ' 4.11

255

107

332.6

1182.8

879.7

.2456 j 4.07

253

108

333.3

1183.0

879.2

.2477 1 4.04

251

109

334.0

1183.3

878 7

.2499

4.00

249

110

334.6

1183.5

878.3

.2521

3.97

?47

111

335.3

1183.7

877.8

.2543

3.93

246

112

336.0

1183.9

877.3

.2564

3.90

243

113

336. 7

1184.1

876.8

.2586

3.86

241

172

MISCELLANEOUS TABLES.

PROPERTIES OF SATURATED STEAM.— CONT.

Total pressure]! per square inch. |

Temperature in Fahrenheit degrees.

Total heat, in Fahrenheit degrees, from water at 32° F.

Latent heat, Fahrenheit degrees.

1 Density, or weight of one cubic foot.

Volume of one pound of steam.

mi Kl!

Illll

Lbs.

Fahr.

Fahr.

Fahr.

Lbs.

Cubic Fest

Rel. Vol.

114

337.4

1184.3

876.3

.2607

3.&3

239

115

338.0

1184.5

875.9

.2628

3.80

237

116

338.6

1184.7

875.5

.2649

i.77

2*5

117

339.3

1164.9

875.0

.2652

3.74

2:w

118

339.9

1185.1

874.5

.2674

3.71

231

119

340.5

1185.3

874.1

.2696

3.68

229

120

341.1

1185.4

873.7

.2738

3.65

227

121

341.8

1185.6

873.2

.2759

3.62

225

122

342 4

1185.8

872.8

.2780

3.59

224

123

343.0

1186.0

872.3

.2801

3.56

2^2

124

343.6

1186.2

871.9

.2822

3.54

221

125

344.2

1186.4

871.5

.2845

3.51

219

126

344.8

1186.6

871.1

.2867

3.49

- I '

127

345.4

1186.8

870.7

.2889

3.46

215

128

346.0

1186.9

870.2

.2911

3.44

214

129

346.6

1187.1

869.8

.2933

3.41

212

130

347.2

1187.3

8*0.4

.2955

3.38

211

131

347.8

1187.5

869.0

.2977

3.35

209

132

348.3

1187.6

868.6

.2999

3.33

20S

133

348.9

1187.8

868.2

.3020

3.31

206

134

349.5

1188.0

867.8

.3040

3.29

205

135

350.1

1188.2

867.4

.3060

3.27

203

136

K50.6

1188.3

867.0

.3080

3.25

202

137

351.2

1188.5

866.6

.3101

3.22

200

138

351.8

1188.7

866.2

.3121

3.20

199

139

352.4

1188.9

865.8

.3142

3.18

198

140

352.9

1189.0

865.4

.3162

3.16

197

141

353.5

1189.2

865.0

.3184

3.14

195

142

364.0

1189.4

864.6

.3206

3.12

194

143

354.5

1189.6

864.2

.3228

3.10

193

144

355.0

1189.7

863.9

.3250

3 08

102

145

355.6

1189.9

863.5

.3273

3.06

190

146

356.1

1190.0

863.1

.3294

3.04

189

147

356.7

1190.2

862.7

.3315

3.02

18.H

148

35T.2

1190.3

862.3

.3H36

3.00

187

149

357.8

1190.5

861.9

.3357

2.98

186

150

358.3

1190 7

861.5

.3377

2.96

184

155

361.0

1191.5

859.7

.3484

2.87

179

160

363.4

1192.2

857 9

.3590

2.79

174

165

366.0

1192.9

856.2

.3695

2.71

169

170

368.2

1193.7

854.5

.3798

2.63

164

175

370.8

1194.4

852.9

.3899

2.56

159

180

372.9

1195.1

851.3

.4009

2.49

155

185

375.3

1195.8

849.6

.4117

2.43

151

190

377.5

1196.5

848.0

.4222

8.37

14S

195

379.7

1197.2

846.5

.4327

2.31

144

200

381.7

1197.8

845.0

.4431

2.26

141

210

386.0

1199.1

841.9

.4634

2.16

135

220

389.9

1200.3

839.2

.4842

2.06

129

230

393.8

1201.5

836.4

.6052

.98

123

240

397.5

1202.6

833. 8

.5248

.90

119

250

401.1

1203.7

831.2

.5464

.83

114

260

404.5

1204.8

828.8

.56K9

.76

110

270

407.9

1205.8

826.4

.5868

.70

108

280

411.2

1206.8

824.1

.6081

.64

102

290

414.4

1207.8

821.8

.6273

.59

99

300

417.5

1208.7

819.6

.6486

.54

93

MISCELLANEOUS TABLES.

173

MEAN EFFECTIVE PRESSURE OF DIAGRAM OF STEAM CYLINDER.

$553313 BaSSSRStS

sis*

The M. E. P. for any initial pressure not given in the table can be found by multiplying- the (absolute) given pressure by the M.E. P. per pound of initial, as given in the third horizontal line of the table.

174

MISCELLANEOUS TABLES.

HEAD OF WATER AND EQUIVALENT PRESS- URE IN POUNDS PER SQUARE INCH.

II

£

•d .5 rti;

w.s

£

'C4J

&

£

M.S

1

Id' &*

£

1

0.43

~41

17.75

81

35.08

121

52.41

161

69.74

2

0.86

42

18.19

82

35.52

122

52.84

162

70.17

3

1.30

43

18.62

83

35.95

>123

53.28

163

70.61

4

1.73

44

19.05

84

36.39

124

53.71

164

71.04

5

2.16

45

19.49

85

36.82

125

54.15

165

71.47

6

2.59

46

19.92

86

37.25

126

54.58

166

71.91

7

3.03

47

20.35

87

37.68

:127

55.01

167

72.34

8

3.46

48

20.79

88

38.12

128

55.44

168

72.77

9

3.89

\ 49

21.22;

89

38.55; 129

55.88

169

73.20

10

4.33

50

21.65

90

39.98

130

56.31

170

73.64

11

4.76

51

22.09

91

39.42

131

56.74

171

74.07

12

5.20

52

22.52

92

39.85

132

57.18

172

74.50

13

5.63

53

22.95

93

40.28

133

57.61

173

74.94

14

6.06

54

23.39

94

40.72

134

58.04

174

75.37

15

6.49

55

23.82

95

41.15

135

58.48

175

75.80

16

6.93

56

24.26

96

41.58

136

58.91

176

76.23

17

7.36

57

24.69

97

42.01

137

59.34

177

76.67

18

7.79

58

25.12

98

42.45

138

59.77

178

77.10

19

8.22

59

25.55'

99

42.88

139

60.21

179

77.53

20

8.66

60

25.99

100

43.31

,140

60.64

180

77.97

21

9.09

61

26.42:

101

43.75

141

61.07

181

78.40

22

9.53

62

26.85

102

44.18

142

61.51

182

78.84

23

9.96

63

27.29

103

44.61

143

61.94

183

79.27

24

10.39

64

27.72

104

45.05

144

62.37

184

79.70

25

10.82

65

28.151

105

45.48

145

62.81

185

80.14

26

11.26

66

28.58

106

45.91

;146

63.24

186

80.57

27

11.69

67

29.02

107

46.34

147

63.67

187

81.00

28

12.12

68

29.45

108

46.78

148

64.10

188

81.43

29

12.55

69

29.88

109

47.21

149

64.54

189

81.87

30

12.99

70

30.32

110

47.64

150

64.97

190

82.30

31

13.42

71

30.75

111

48.08

151

65.49

191

82.77

32

13.86

72

31.18

112

48.51

152

65.84

192

83.13

33

14.29

73

31.62llll3

48.94

153

66.27

193

83.60

34

14.72

74

32.05

114

49.38

154

66.70

194

84.03

35

15.16

75

32.48

115

49.81

155

67.14

195

84.47

36

15.59

76

32.92

116

50.24

156

67.57

196

84.90

37

16.02

77

33.35

117

50.68

157

68.00

197

85.33

38

16.45

78

33.78

118

51.11

158

68.43

198

85.76

39

16.89

79

34.21

119

51.54

|159

68.87

199

86.20

40

17.32

80

34.65J 120

51.98

1160

69.31

200

86.63

MISCELLANEOUS TABLES.

175

TABLE SHOWING PROPERTIES OF SOLUTION OF SALT.

(Chloride of Sodium.)

Percentage of Salt by M Weig-ht.

Pounds of Salt per Gallon of w Solution.

3

C !-> "|?

Q$ rt

Weight per Gallon at ^ 39° P.-4° C.

5

a«o

•|£°T •

*!£.

6

y

£ -^ J) o)

W

Freezing- Point, -a Fahrenheit.

1

9

0.084 0 169

4 g

8.40 8 46

1.007 1 015

0.992

30.5 29 3

2 5

0 212

10

8 50

1 019

28 6

3

0 256

12

8 53

1 023

27 8

3 5

0 300

14

8 56

1 026

27 1

4

0 344

16

8 59

1 030

26 6

5

0.433

20

8.65

1.037

0.960

25.2

6

0 523

24

8 72

1 045

23 9

7

0 617

28

8 78

1 053

22 5

8

0 708

32

8 85

1 061

21 2

9 10

0.802 0.897

36 40

8.91 8.97

1.068 1.076

6 '.892

19.9 18.7

12 15 20

1.092

1.389 1.928

48 60 80

9.10 9.26 9.64

1.091 1.115 1.155

6 '.855 0.829

16.0 12.2 6.1

24

2 376

96

9 90

1 187

1 2

25 26 29

2.488 2.610

100

9.97 10.04

1.196 1.204

0.783

.5 —1.1

—4.7

To determine the weig-ht of one cubic foot of brine, multiply the values given in column 4 by 7.48.

To determine the weig-ht of salt to one cubic foot of brine, multiply the values given in column 2 by 7.48.

PROPERTIES OF SOLUTION OF CHLORIDE OF CALCIUM.

Percentage by Weight.

Specific Heat.

Spec. Grav. at 60° F.

Freezing Point, Degrees F.

Freezing Point, Deg. Cels.

1

0.996

1.009

31

— 0.5

5

0.964

1.043

27.5

— 2.5

10

0.896

1.087

22

— 5.6

15

0.860

1.134

15

— 9.6

20

0.834

1.182

- 1.5

—14.8

25

0.790

1.234

—21.8

—22.1

176

MISCELLANEOUS TABLES.

DIAMETERS, AREAS AND CIRCUMFERENCES OF CIRCLES.

Diam. | Inches.

Circumf. Inches.

I-

<s

ll

E^ ao 1»

^x;

i*

if

a "> B <u

3£Z

«^ ' o>

QC

b G bw

*&

QC

£S o

<ti

1

3.14159

0.78540

4

12.5664

12 566

8

25 1327

50.265

, jtj

3.3379.4

0.88664'

1*0

12.7627

12.962

'/8

25 5224

;>1.849

1 '4

3.53429

0.99402

1

12.9591

13.364

*4

2f>. 91 8 1

53.456

ft

3.73064

.1076

,3*

13.1554

13.772

%

26.3108

56.0b8

3.92699

.2272

k

13.3518.

14.186

l/2

26.7035

56.746

isl

4.12334

.3530

i5f,

13.5481

14.607

X

27.0962

58.426

x

4.31969

.4849

%

13.7445

15.033

%

27. 4889

60.132

1 6

4.51604

.6230

J76

13.9408

15.466

27. f 816

61.862

Va

4.71239

.7671

K

14.1372

15.904

9

28.2743

63.617

,"6

4.90874

.9175

ft

14.3335

16.349

H

28. 6670

65.397

%

5.10509

2.0739

%

14.5299

16.1-00

H

29.0597

67.201

U

5.30144

2.236C

{I

14.7^62

17.257

%

29.4624

69.029

a4

5.49779

2.4053

£

14. 9226

17.721

%

29.8451

70.882

1 3

5.69414

2.5802

n

15.1189

18.190

%

30.2378

72.760

X

5.89049

2.7612

%

15.3153

18.665

%

30.6305

74.662

18

6.08684

2.9483

\i

15.5116

19.147

%

31.0232

76.689

2

6.2*319

3.1416

5

15.70PO

19 635

10

31 4159

78.540

,!B

6.47953

3.3410

A

15.9043

20.129

y±

32.2013

82.516

M

6.67588

3.54«6

%

16.1007

20.629

Yz

32.9*67

86.590

ft

6.87223

3.7583

A.

16.2970

21.135

\

33.7721

90.763

J4

7.06858

3.9761

H

16.4934

21.648

11

3-4.5575

95.033

156

7.26493

4.2000

1*8

16.6897

22.166

1A

35.3429

99.402

%

7.46128

4.4301

%

16.8861

22.6H1

£

36.1283

103.87

7.65763

4.6664

I7*

17.0824

23.221

K

36.9137

108.43

*/2

7.85398

4.9087

K

17.2788

23.758

12

37.6991

113.10

198

8.05033

5.1572

:!98

17.4751

24.301

y*

38.4845

117.86

H

8.24668

5.4119

%

17.6715

24.850

%

39.2699

122.72

H

8.44303

5,6727

\l

17.8678

25.406

%

40.0563

127.68

\

8.63938

5.9396

X

18.0642

25 967

13

40.8407

132.73

1*

8.83573

6.2126

tf

18.2605

26.535

H

il.6261

137.89

%

9.03208

6.4918

%

18.4569

27 .'109

V4

42.4115

143.14

11

9.22843

6.7771

18

18.6532

27.688

M

43.1969

148.49

3

9.424:8

7.0686

6

18.8496

28.274

14

43.9823

153.94

•iVs

9.62113

7.3662

H

19.2423

29.465

y\

44.7671

159.48

H-

9.81748

7.6699

H

19.6350

30.680

Vz

45.5531

165.13

•>36

10.0138

7.9798

%

20.0277

31.919

X

46.3385

170.87

H

10.2102

8.2958

1A'

20.4204

33.183

15

47.1239

176.71

IB

10.4065

8.6179

%

20.8131

34.472

H

47.9'093

182.65

%'

10.P029

8.9462

%

21.2058

35.785

54

48.6947

188.69

1?R

10.7992

9.2806

%

21.5984

37.122

49.48D1

194.83

H

10.9956

9.6211

1

21.9911

38.485

16

50.2655

201.06

ft"

11.1919

9.9678

y*

22.3838

39.871

y*

51.0509

207.39

«

11.3883

10.321

M

22.7765

41.282

H

51.8363

213.82

Ji

11.5846

10.680

%

23.1692

42.718

\

52.6217

220.35

%

11.7810

11.045

l/2

23.5619

44.179

17

53.4071

226.98

ia

I <>

11.9772

11.416

5jj

23.9546

45.664

k

54.1925

233.71

•fe

12.1737

11.793

%

24.3473

47.173

l/2

54.9779

240.53

.18

12.3700

12.177

7/9

24.7400

48.707

#5.7(533

247.45

MISCELLANEOUS TABLES.

177

DIAMETERS, AREAS AND CIRCUMFERENCES OF CIRCLES.— CONTINUED.

a| .2-3

Qfl

Circumt". Inches.

• 1

ll

Diam. Inches.

Circumf. Inches.

•> .

Diam. I Inches.

Circumf. Inches.

s

18

56.5487

254.47

J3

100 531

804 25

46

144.513

1661.9

57 3341

261.59

/4

101.316

816.86

/4

145.21)9

1680.0

H

58.1195

268 80

Yz

102.102

829.58

Yz

146 U84

1698.2

X

58.9049

276.12

%

102 887

842.39

34

146 86!)

1716 5

19

59.6903

283.53

33

103 673

855.30

47' '

147 65.'

1734 9

60 47.37

291.04

104.458

868.31

/4

148.440

1753.5

Yz

61.2611

208.65

Yz

105 243

881.41

Yz

149.226

1772 J

%

62.0465

306'. 35

?4

106.029

894.62

%

150.011

1790.8

20

62.8319

314.16

34

106.814

907.92

48

150.796

1809 6

63.6173

322.06

107.600

921.32

151.582

1828.5

Yz

64.4036

330.06

Yz

108.385

934.82

Yz

152.367

1847.5

"X

66.1830

338.16

%

109.170

948.42

%

153.153

1866.5

21

65.9734

346.36

35'

109.956

962.11

49

153.938

1885.7

66.7588

354.66

X

110.741

975.91

Y\

154.723

1905.0

V»

67.5442

363.05

Yz

111.627

989. 80

Yz

155.509

1924.2

X

68.3398

371.54

112.312

1003.8

$4.

156.294

1943.9

69.1150

380.13

36 4

113.097

1017.9 .

50

157.080

1963.5

1

69.9004

388.82

\2

113.883

1032.1

\i

157.865

1983.2

%

70.6858

397.61

•%

114.668

1046.3

Yz

158.650

2003.0

^

71 4712

406.49

%

115.454

1060.7

159.436

2022.8

23

72.2566

415.48

3?

116.239

1075.2

51 4

160.221

2042.8

73.0420

424.56

Y± 117.024

1089.8

161.007

2062.9

/4

73.8274

433.74

M

117.810

1104.5

Yz

161.792

2083.1

24

74.6128

443.01

X

118.596

1119.2

%

162 577

2103.3

24

75.3982

452.39

38

119.381

1134.1

52

163.363

2123.7

76.1836

461.86

X

120.166

1149.1

164.148

2144.2

^2

76.9690

471.44

120.951

1164.2

~" Yz

164.934

2164.8

Jj£

77.7544

481.11

%

121.737

1179.3

%

165.719

2185.4

25

78.5398

490.87

39

122.522

1194.6

53

166.504

2206.2

\,'

79.3252

500.74

123.308

1310.0

J4

167.290

2227.0

Yt

80.1106

510.71

Yz

124.093

1225.4

Yz

168.075

2248.0

80.8960

620.77

124.878

1241.0

94

168.861

2269.1

26^

81.6814

630.93

404

125.664

1266.6

54

169.. 646

2290.3

82.4668

541. 19

126.449

1272.4

170.431

2311.5

i^

83.2522

551.55

y*

127.235

1288.2

Yz

171.217

2332.8

2 '

84.0376

562.00

128.020

1304.2

172.002

2354.3

27*

84.8230

572.66

414

128.805

1320.3

55^

172.788

2376.8

85.6084

583.21

129.591

1336.4

X

173.573

2397.5

Yt

86.3938

593.96

X

130.376

1352.7

174.358

2419.2

94

87.1792

604.81

94

131.161

1369.0

94

175.144

2441.1

28

87.9646

615.75

42

131.947

1385.4

56

175.929

2463.0

J4

88.7500

626.80

J4

132. 732

1402.0

176.715

2485.0

!4

89.5354

637.94

133.518

1418.6

4

177.500

2607.2

a^

90.3208

649.18

24

134.303

1436.4

178.285

2529.4

29

91.1062

660.52

43-

135.088

1452.2

57 4

179.071

2551.8

/4

91.8916

671.96

i •

135.874-

1469.1

/4

179.856

2574.2

Yz

92.67r<0

683.49

Y«

136.659

1486.2

y*

180.642

2596.7

%

93.4624

695.13

X

137 445

1503.3

24

181.427

2619.4

30

94.2478

706.86

44

138.230

1620.5

58

182.212

2642.1

95.0332

718.69

139.015

1537.9

i^

182.998

2664.9

8

95.8186

730.62

Yz

139.801

1555.3

<y

183.783

2687.8

96.6040

742.64

94

140.586

1572.8

%

184.569

2710.9

31.4

97.3894

754.77

45

141.372

1590.4

59

1&5.354

2734.0

98.1748

766.99

X

142.157

1608.2

186.139

2757.2

%

98.9602

779.31

Yz

142.942

1626.0

Yz

186.925

2780.5

%

99.7466

791.73

143.728

1643.9

%

187. 7JO

2803.9

178

MISCELLANEOUS TABLES.

DIAMETERS, AREAS AND CIRCUMFERENCES OF CIRCLES.— CONTINUED.

rig

«*H •

g en

• f3

at

ii

d£

S£

•J

§1

»S

3,a ££ 0M

$?•

!•§

QC

XA ^d

o"

ll

d.a o o ^a Ow

«M

60

188.496

2827.4

74

232.478

4300.8

88

276.460

6082.1

%

189.281

2851.0

k.

233.263

4329.9

/4

277.246

6116.7

2

190.066

2874.8

234.049

4359.2

Y~

278.031

6151.4

190.852

2898.6

5

234.834

4388.5

%

278.816

6186.2

61*

191.637

2922.5

75

235.619

4417.9

89

279.602

6221.1

192.423

2946.5 !

236.405

4447.4

280.387

6256.1

'Yz

193.208

2970.6

y2

237.190

4477,0

y?.

281.173

6291.2

%

193.993

2994:8 !

%

237.976

4506.7

%

281.958

6326.4

®i

194.779

3019.1

76

238.761

4536.5

90

282.743

6361.7

195.564

3043.5

y±

239.546

4566.4

Ji

283.629

6397.1

Vt

196.35JU

3068.0

Yz

240.332

4596.3

Yt

284.314

6432.6

197.135

3092.6

241.117

4626.4

285.100

6468.2

63*

197.920

3117.2

77

241.903

4656.6

91*

288.885

6503.9

198.706

3142.0

/4

242. 688

4686.9

/4

286.670

6539.7

Yz

199.491

3166,9

Yz

243.473

4717.3

287.466

6575 5

200.277

3191.9

%.

244.259

4747.8

2i

288.241

6611.5

644

201.062

3217.0

78

245.044

4778.4

92

289.027

6647.6

201.847

3242.2

245.830

4809.0

289.812

6683.8

Yz

202.633

3267.5

Yz

246.615

4839.8

Yz

290.597

6720.1

%

203.418

3292.8

3L'

247.400

4870.7

M

291.383

6766.4

65

204.204

3318.?

79

248.186

4901.7

93

292.168

6792.9

204.989

3343.9

y*.

248.971

4932.7

/4

292.954

6829. 5

Yz

205.774

3369.6

y*

249.757

4963.9

Yz

293.739

6866.1

%

206.560

3395.3

250.542

4995.2

%

294.524

6902.9

66

207.345

3421.2

80*.

261.327

5026.5

94

295.310

6939.8

/4

208.131

3447.2

i>

252.113

5058.0

!/•

296.095

6976.7

•V6

208.916

3473T2

H

252.898

5089.6

Yz

296.881

7013.8

9£

209.701

3499.4

253.684

5121.2

%

297.666

7051.0

67

210.487

3526."

81*

254.469

5153.0

95

298.451

7088.2

/4

211.272

3552.0

H

255.254

5184.9

14

299.237

7125.6

i^

212.058

3578.5

Yz

256.040

5216.8

i/

300.022

7163.0

M

212.843

3605.0

256.825

5248.9

If

300.807

7200.6

68'

213.628

3631.7

82*

257.611

5281.0

96

301.593

7238.2

/4

214.414

3658.4

/4

258.396

5313.3

\A

302.378

7276.0

14

215.199

3685.3

Yz

259.181

5345.6

Yz

303.164

7313.8

3i

215.984

3712.2

%

259.967

5378.1

303.949

7361.8

69

216.770

3739.3

83

260.752

5410.6

97 /4

304.734

7389.8

K

217.555

3766.4

y±

261.538

5443.3

/4

305.520

7428.0

H

2I8.-341

3793-7

Yz

262.323

5^76 0

Yz

306.305

7466:2

219.126

3821.0

%.

263.108

5508.8

%

307.091

7504.5

70*

219.911

3848. 5

84 .

263.894

5541.8

98

307.876

7543.0

/£

220.697

3876.0

264.679

5574.8

H

308.661

7581:5

Yz

221.482

3903.6

y*

265.465

5607.9

309.447

7620.1

%

222.268

3931.4

%

266.260

5641.2

%

310-232

7658.9

71

223.053

3959.2

85

267.035

5674.5

99

311.018

7697.7

"/£

223.838

3987.1

i/

267.821

5707.9

M

311.803

7736.6

Va

224.624

4015.2

Yz

268.606

5741.5

Yz

312.588

7775.6

%

225. 409

4043.3

%

269.392

5775.1

%

313.374

7814.8

72

226.195

4011.5

86

270.177

5808.8

100

314.159

7854 0

/i

226.980

4099.8

/4

270. 962

5842.6

y2

227.765

4128.2

Yz

271.748

5876.5

3£

228.551

4156.8

%

272.533

5910.6

"•"S

229.336

4185.4

87

273.319

5944.7

Ji

230.122

4214.1

274.104

5978.9

i4

230.907

4242.9

Yz

274.889

6013.2

231.692

4271.8

275.675

r>047.fi

MISCELLANEOUS TABLES. 179

TABLE OF PISTON SPEEDS.— FEET PER MINUTE

Stroke in Inches.

s

.00 co oo

) O X*. to

1 00 -4 O

. *- O 00 Oi .«>. OO tG O «O 00 00 i oo O •<> O<iOJ O -^ 00 O I C^

58l 8

)<l OS V yi i*^ >U >U ; ' t* O OS M 00 >U O <

> C O O O O O C i

> o o o o ^

IS3SSI £

4w Ci

^^C^

;5§8l.i

l£i_i-ii— _M

"to~to to -» i-n

liil i

rf^. C5 OiiOOOO»*i*OtC4X.O

PllfSillilSSjggStSSfeSg!

_o i—1 o_o ojo oa o o CT> oo o — ? oo-o <i. w oo o oo -^ m i

"iC CO.'ltC K>"tO >-*"— M t-i i-i' i^Ti- i-i " " ~

~co co"oo tototcrc>-'M>— h^i-n-ii-i

^§88g8S:

!£3 SS

)<JO» I O»

^ O O O O ^C Oi O O O5 OC' O Ci 00 O O '

o^Ooo^>o;ooo5>-'C5--i£So-:b<

ADVERTISEMENTS.

*j£ot3£C:<3

«f | S, 5 K- 5 » I mm

"1 £ C (D «J 3 f"™1 *••>

SJBpBBP^S p-n g

T CO IT" ~ — ••• PHHI

W3 O P^ >^^/ O ^PV *r _^t

mifiB »* s iiii a

05 O (t 2 S O &1 ^B'-R*1

•• 09 • p< i R) n ® i

ADVERTISEMENTS.

GARDNER T. VOORHEES, S. B

Refrigerating

engineer

OPINIONS, ESTIMATES, PLANS, ETC.,

FOR

Refrigerating^Ice Plants

INDICATOR CARDS WORKED UP, ETC.

41 RICHMOND STREET BOSTON

ADVERTISEMENTS.

HOW DO YOU KNOW

Whether your ENGINE is working- ECONOMICALLY and developing- FULL POW- ER for FUEL consumed ? NOTHING but an INDICA- TOR will give you this knowl- edge, and there is no INDICATOR su- perior to the IMPROVED ROBERTSON THOMPSON, and the price is about one- third lower than any other.

works WET steam or BOILER foams, a HINE ELIMINATOR will correct both at trifling- cost.

IF YOUR ENGINE

WET steam or BOILER fc E ELIMINATOR will correct ing- cost.

JAS. L. ROBERTSON & SONS, 204 Fulton Street, NEW YORK

"BOYLE"

ice Making and Refrigerating Machinery

BUILT BY THE

Pennsylvania Iron Works Company

PHILADELPHIA

New York Office, 621 Broadway

A HANDSOMELY ILLUSTRATED CATALOGUE SENT ON APPLICATION.

Also Builders of the....

Qas and Gasoline Engines....

For Stationary and Marine Service.

ADVERTISEMENTS.

STflR BRflSS MFG. GO.

MANUFACTURERS OF

HIGHEST GRADE

Ammonia Gages

FOR

Ice and Refrigerating

Machines

ALSO ORIGINAL AND

EXCLUSIVE MANUFACTURERS OF

"Non -Corrosive'' Pressure and Vacuum Gages

OF ALL DESCRIPTIONS

ALSO

Solid Nickel Seated Pop Satety Valves.

NOTE— Our gages are used exclusively by the Quincy Market Cold Storage Co.. Boston.

SPECIFY THEM ON NEW EQUIPMENT

108-114 East Dedham Street, BOSTON, MASS.

THIRD EDITION

Compend of

Mechanical

Refrigeration

BY

PROF. J. E. SIEBEL.

DnirwJ Bound in Cloth, - $8.00 ' ' v -1 in Morocco, 3.50

ON RECEIPT OF PRICE

H. S, RICH & CO.,

Publishers

206 BROADWAY 177 LA SALLE ST.

NEW YORK CHICAGO

ADVKRTISKMENTS.

TUB BJCHELDER "ST IIDICBTOR

AND IDEAL REDUCING WHEEL

COMPLETE,

COMPACT

AND

RELIABLE

JOHN s. BUSHNELL,SOLE MANUFACTURER

(SUCCESSOR TO THOMPSON &. BUSHNELL)

120 AND 122 LIBERTY ST., NEW YORK

Practical Ice Making and

Refrigerating

A practical, common sense treatise on the construction and operation of Ice Making- and Refrigerating- Machinery and Apparatus : : : :

El LJ G E IM E: T. S K I IVJ K l_ El .

"THE BOY"

BOUND ix CLOTH, ........ $1.50

j BOUND IN MOROCCO, ........ 2.00

SENT PREPAID TO ANY ADDRESS ON RECEIPT OF PRICE.

& CO., Rutoli

177 La s:il I., st., CHICAGO 206 Broadway, NEW YORK

39 (402s)

ml *-^/^ I OOUO

THE FRED W. WOLF Co.

Cable A

Manufacturers Export

and Engineers and Architects A. B. c. Code Used.

MANUFACTUKKKS OK

THE LINDE ICE MAKING

in actual operation, and Refrigerating Machine

4 times as many as any other ice machine.

For Durability, Simplicity and It Has No Equal

Ammonia Fittings

Ice Factory Supplies

T^J-32

Ammonia Condensers, Ice Can Thawing Dumps,

Baudelot Coolers, Ice Tools,

Direct Expansion Piping, Pumps,

Brine Piping, Derricks, Etc.

General Offices, 139=143 Rees Street, Foot of Dayton Factory, 302-330 Hawthorne Avenue

CHICAGO, U. S. A.

Catalogs Sent on Application.

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