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Full text of "Hydraulic experiments with valves, orifices, hose, nozzles, and orifice buckets"

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F ILLINOIS BULLETIN 

ISSUED WEEKLY 
MAY 13, 1918 No. 37 

-second-class matter Dec. 11, 1012, at the Post Office at Urbana. 111., under the Aet of Aur. 24. 1912.1 



HYDRAULIC EXPERIMENTS WITH 

VALVES, ORIFICES, HOSE, NOZZLES, 

AND ORIFICE BUCKETS 



BY 



ARTHUR N. TALBOT, FRED B SEELY,^ 
VIRGIL R FLEMING, MELVIN L. ENGER 




BULLETIN No. 105 
ENGINEERING EXPERIMENT STATION 

PUBLISHED BY THE UNIVERSITY OF 1 NOIS, URBANA 



PRICE: 'i HTRTT-IITB CENTS 

EUROPEAN AGENT 
CHAPMAN & HALL, LTD., LONDON 



CHANGE 




Wtfttf? 



UNIVERSITY OF ILLINOIS 
ENGINEERING EXPERIMENT STATION 

BULLETIN No. 105 MAY, 1918 



HYDRAULIC EXPERIMENTS WITH VALYES, 

ORIFICES, HOSE, NOZZLES, AND 

ORIFICE BUCKETS 



PART I 
Loss OF HYDRAULIC HEAD IN SMALL VALVES 

BY ARTHUR N. TALBOT 

PROFESSOR OF MUNICIPAL AND SANITARY ENGINEERING 
IN CHARGE OF THEORETICAL AND APPLIED MECHANICS 

AND 

FRED B SEELY 

ASSISTANT PROFESSOR OF THEORETICAL AND APPLIED MECHANICS 

PART II 
THE FLOW OF WATER THROUGH SUBMERGED ORIFICES 

BY FRED B SEELY 
ASSISTANT PROFESSOR OF THEORETICAL AND APPLIED MECHANICS 

PART III 

FIRE STREAMS FROM SMALL HOSE AND NOZZLES 
BY VIRGIL R FLEMING 

ASSISTANT PROFESSOR OF APPLIED MECHANICS 

PART IV 

THE ORIFICE BUCKET FOR MEASURING WATER 

BY MELVIN L. ENGER 
ASSOCIATE PROFESSOR OF MECHANICS AND HYDRAULICS 



ENGINEERING EXPERIMENT STATION 

PUBLISHED BY THE UNIVERSITY OF ILLINOIS, URBANA 







PREFACE 

AS a part of the experimental work conducted in the Hydraulic 
-*"* Laboratory of the University of Illinois a number of problems 
has been investigated which has not been large enough in scope to war- 
rant publication as separate bulletins. It seems well, however, to put 
on record the results of such experiments, and this bulletin presents 
a record of four of these problems. It is believed that the four papers 
will be found to be of use in various aspects of engineering practice 
even though the experiments are not exhaustive investigations. 

The investigations for the most part have been the outgrowth of 
experimental work begun by students, largely as thesis work, and car- 
ried on over a period of several years. 

The variety of conditions under which the flow of water takes 
place, the possibility of large changes in the state of the flow due appar- 
ently to small changes in the form of the passages through which the 
water flows, and the necessity of persistent effort in subjecting assump- 
tions and analytical deductions to experimental verification, make it 
desirable to report all hydraulic experimental results which are believed 
to be reliable. 

A part of the experimental results herein reported has appeared 
in the publication of a technical society. The material, however, has 
been expanded in this bulletin and will be found in a more convenient 

form for use. 

ARTHUR N. TALBOT 

FRED B SEELY 

Editors 



PART I 
LOSS OF HYDRAULIC HEAD IN SMALL VALVES 

BY ARTHUR N. TALBOT 
PROFESSOR OF MUNICIPAL AND SANITARY ENGINEERING 
IN CHARGE OF THEORETICAL AND APPLIED MECHANICS 

AND 

FRED B SEELY 

ASSISTANT PROFESSOR OF THEORETICAL AND APPLIED MECHANICS 



387318 



CONTENTS 

PART I 
LOSS OF HYDRAULIC HEAD IN SMALL VALVES 

PAGE 

I. INTRODUCTION 7 

1. Preliminary 7 

2. Acknowledgment 7 

II. APPARATUS AND METHOD OF EXPERIMENTING .... 8 

3. Valves 8 

4. Method of Experimenting 8 

III. EXPERIMENTAL RESULTS AND DISCUSSION . . . . . 10 

5. Loss of Head 10 

6. Earlier Experiments on Gate Valves 18 

7. Coefficients of Discharge for Gate Valves .... 20 

8. Summary 21 



LIST OF FIGURES 

NO. PAGE 

1. Longitudinal Sections of Valves Tested 9 

2. Arrangement of Apparatus . 11 



3. Curves Showing the Relation between the Velocity and Head Lost in 

1-inch Gate Valve ....'... 13 

4. Curves Showing the Relation between the Velocity and Head Lost in 

2-inch Gate Valve 13 

5. Curves Showing the Relation between the Velocity and Head Lost in 

1-inch Globe Valve .14 

6. Curves Showing the Relation between the Velocity and Head Lost in 

2-inch Globe Valve 14 

7. Curves Showing the Relation between the Velocity and Head Lost in 

1-inch Angle Valve 15 

8. Curves Showing the Relation between the Velocity and Head Lost in 

2-inch Angle Valve 15 

9. Curves Showing the Relation between Coefficients of Loss and Valve 

Openings 16 

10. Curves Showing the Effect of Gradual Change of Section through 2-inch 

Globe Valve . 17 



LIST OF TABLES 

1. Experimental Values of Coefficients of Loss 16 

2. Values of the Coefficient of Loss for Gate Valves of Various Diameters 

Due to Partial Closure Only 19 

3. Experimental Values of the Coefficients of Discharge for Gate Valves . 20 



HYDRAULIC EXPERIMENTS 

WITH 

VALVES, ORIFICES, HOSE, NOZZLES, AND 
ORIFICE BUCKETS 



PART I 
LOSS OF HYDRAULIC HEAD IN SMALL VALVES 



I. INTRODUCTION 

1. Preliminary. Part I of this bulletin presents the results of 
experiments on the flow of water through 1-in. and 2-in. gate valves, 
1-in. and 2-in. globe valves, and 1-in. and 2-in. angle valves. The loss 
of head caused by each valve, expressed in terms of the velocity head 
in the pipe, is given for four different ratios of the height of the valve 
opening to the diameter of the full valve orifice, namely, M, /^, H, 
and 1. The coefficients of discharge are also given for the gate valves 
for each of the four valve openings. 

In a long pipe line the total amount of lost head is caused chiefly 
by pipe friction, the resistance due to a valve being comparatively small 
except for very small valve openings. 

In a variety of cases, however, where valves are used on compara- 
tively short pipe lines as, for example, in hydraulic elevator service, in 
office buildings, and in special apparatus it is important to know the 
lost head caused by small valves of different kinds when set at various 
positions. Very few experimental results have been published on this 
subject, particularly for globe and angle valves. Any experimental 
work, furthermore, which helps to indicate the laws governing the flow 
of water should prove of value. With these facts in mind the results 
herein recorded have been prepared. 

2. Acknowledgment. The experiments herein considered were per- 
formed as student thesis work in the Hydraulic Laboratory of the Uni- 
versity of Illinois by M. E. THOMAS, class of 1906, under the direction 
of PROFESSOR ARTHUR N. TALBOT. Unusual care in the experimenting is 
reflected in the congruity of the data presented in Mr. Thomas' thesis. 

7 



ILLINOIS ENGINEERING EXPERIMENT STATION 



II. APPARATUS AND METHOD OF EXPERIMENTING 

3, Valves. The valves used were bought in the open market 
and tested just as received. The passages through the 2-in. globe 
valve were then modified by the use of plaster of paris to give a more 
gradual change of section (see Fig. 10), and this valve was tested again. 
The types or forms of the interiors of the valves and the dimensions of 
some of the passageways through the valves are shown in Fig. 1. The 
1-in. globe valve and the 1-in. angle valve were made by the Western 
Tube Company. All the other valves were made by the Crane Company. 

4. Method of Experimenting. The arrangement of the apparatus 
is shown in Fig. 2. The test valve was placed in a horizontal pipe to 
which water was supplied from a standpipe under a static head of about 
50 feet. The quantity of water discharged through the valve was 
regulated by another valve downstream from the test valve. The 
volume discharged in a certain time was measured in a calibrated pit 
and the time taken with an ordinary watch from which the rate of 
discharge was calculated. Three-way gage connections for obtaining 
the pressure head in the pipe were made at a section one foot upstream 
and one foot downstream from the valve. Care was taken to avoid 
having these connections project into the interior of the pipe. It was 
found by experiment that when any two of the three pressure connec- 
tions at either section were closed, the same difference of head was 
registered as when all three connections at either section were open. 
The three-way connections were used, however, in all the experiments. 
The difference in the pressure heads at the two sections was measured 
by a differential mercury gage. A Crosby pressure gage was also 
attached at each section to serve as a rough check on the differential 
gage. The lost head due to the pipe friction for the two feet of pipe 
between the two sections was assumed to be as given in Weston's Tables 
of Friction of Water in Pipes. This amount of lost head was subtracted 
from the reading of the differential mercury gage in determining the loss 
of head caused by the valve. 

The loss of head and the corresponding rate of discharge and 
velocity in the pipe were determined for each of four valve openings for 
each of the six valves tested. The valve openings used were such that 
the heights of the openings were one-fourth, one-half, three-fourths, and 
one times the diameter of the full valve orifice. 



HYDRAULIC EXPERIMENTS 




One- Inch Gate Valve 



Two-Inch Gate Valve 




One-Inch Angle Valve Two-Inch Angle Valve 

FIG. 1. LONGITUDINAL SECTIONS OF VALVES TESTED 



10 ILLINOIS ENGINEERING EXPERIMENT STATION 



III. EXPERIMENTAL RESULTS AND DISCUSSION 

5. Loss of Head. In Fig. 3 to 8 values of the lost head caused 
by the valve are plotted as abscissas and the mean velocity in the pipe 
as ordinates. The assumed value of the friction head for the two feet 
of pipe between pressure connections is subtracted from the differential 
mercury gage reading in plotting the abscissas. There is, of course, 
some doubt concerning the correct allowance to be made for this pipe 
friction. The loss of head due to this cause, however, will be relatively 
small except for the larger valve openings. It will be noted from the 
curves in Fig. 3 to 8 that the range of velocity in the pipe varied of 
course with the kind of valve and with the amount of valve opening. 
The smallest mean velocity in any case was about % ft. per sec., while 
the maximum mean velocity was about 40 ft. per sec. 

The curves in Fig. 3 to 8 give values of the loss of head caused 
by the valves which vary as the square of the velocity in the pipe, that 
is,, the lost head due to the valve may be expressed in terms of the 
velocity head in the pipe. This fact is shown very clearly by plotting 
the values from the curves in Fig. 3 to 8 on logarithmic paper; the 
curves showing the relation between the lost head, h, and the velocity 
in the pipe, v, become parallel straight lines with a slope varying but 
little from two, the slope indicating the exponent in the equation 
h kv n . That is, h = kv 2 or, when expressed in terms of the velocity 

head in the pipe, h = -~- in which m is called the coefficient of loss. 

Values of the coefficients of loss for the valves with the various valve 
openings as obtained from the curves in Fig. 3 to 8 are given in Table 1. 
These values have been plotted in Fig. 9 as abscissas against the valve 
openings as ordinates. From these curves and also from Table 1 the 
resistance to flow caused by the three kinds of valves may be com- 
pared at various valve openings. It will be noted that the loss of head 
varies in a quite different manner with the amount of valve opening for 
these three kinds of valves, for instance, a comparison of the results 
for the valves when completely opened shows that a globe valve causes 
more than twice as much loss of head as the corresponding size of angle 
valve, while a gate valve causes markedly less loss than either a globe or 
an angle valve, the velocity in the pipe being the same in the three 
cases. As the valve is gradually closed, the resistance to flow of the 
angle valves increases the least (decreasing at first) while the resistance 







T -, 



FIG. 2. ARRANGEMENT OF APPARATUS 



HYDRAULIC EXPERIMENTS 



13 




02-46 8- IO 12 14 16 18 2O 22 24 26 28 JO 32 34 36 38 <4O 

Head Lost , /? 

FIG. 3. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN I-INCH GATE VALVE 




30 32 34 36 38 4O 



24 6 8 10 12 14 16 18 20 22 24 26 

head Lost t ft. 

FIG. 4. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN 2-iNCH GATE VALVE 



14 



ILLINOIS ENGINEERING EXPERIMENT STATION 



2 4 6 6 10 12 14 16 18 20 22 24 26 28 3O 32 J4 36 38 




FIG. 5. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN I-INCH GLOBE VALVE 




FIG. 6. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN 2-iNCH GLOBE VALVE 



HYDRAULIC EXPERIMENTS 



15 




O 2 4 6 8 10 IZ 14 16 18 2O 22 24 26 28 JO 32 34 36 38 40 

head Lost. ft. 

FIG. 7. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN I-INCH ANGLE VALVE 



23 




6 B IO 12 14 IS /8 2O 22 24 26 28 3O 32 34 36 38 4O 

/lead Lost, ft 

FIG. 8. CURVES SHOWING THE RELATION BETWEEN THE VELOCITY AND 
HEAD LOST IN 2-iNCH ANGLE VALVE 



16 



ILLINOIS ENGINEERING EXPERIMENT STATION 



of the gate valves increases the most rapidly, although the rate of 
increase in any case is comparatively small until the valve is at least 
one-half closed. 




10 



^0 30 40 SO 60 

Coefficientofioss- m /n h=mj- 



70 



FIG. 9. CURVES SHOWING THE RELATION BETWEEN COEFFICIENTS OF 
Loss AND VALVE OPENINGS 

Fig. 9 also indicates that the proportions or form or shape of the 
passageways of the valve of a given type or kind is a very important 
factor in causing loss of head. This fact is shown by a comparison of 
the results for the 1-in. globe valve with those for the 2-in. globe valve 
and also by a comparison of the results of the 1-in. angle valve with 
those of the 2-in. angle valve. Each of these 1-in. valves was of a 
somewhat different form from that of the corresponding 2-in. valve as 
may be seen in Fig. 1. It will be noted from Fig. 9 and Table 1 that 

TABLE 1 
EXPERIMENTAL VALUES OF COEFFICIENTS OF Loss 

Values of m in h = -= 





Gate Valves 


Globe Valves 


Angle Valves 


Ratio of Height of Valve- 
Opening to Diameter of 
Full Valve Opening 








1-inch 
Diameter 


2-inch 
Diameter 


1-inch 
Diameter 


2-inch 
Diameter 


1-inch 
Diameter 


2-inch 
Diameter 




73.0 


18.8 


16.6 


60.0 


5.00 


7.3 


/4 


7.0 


2.94 


9.62 


10.9 


2.90 


1.70 


% 


1.84 


1.06 


8.75 


6.84 


2.72 


1.44 


1 


0.74 


0.35 


7.12 


6.0 


3.23 


1.70 



HYDRAULIC EXPERIMENTS 



17 



for the smaller valve openings the 1-in. globe valve and the 1-in. angle 
valve cause less resistance to flow than the corresponding 2-in. valves. 
The difference is especially large in the case of the globe valves. This 
unexpected result seems to be due chiefly to the better shaped dis- 
charge passages (more gradual expansion) as the water makes its 
exit from the 1-in. globe valve. 

Experiments were made on the 2-in. globe valve to see if a more 
gradual change in sections through the valve would cause less loss of 
head. This gradual change was made by filling in part of the passage- 
way with plaster of paris, as shown in Fig. 10. This modified valve was 
then tested with the valve one-half open and wide open, the results for 
which are shown in Fig. 10. It will be seen that this modification had no 




/6 80 

Head lost jn Feet 



36 



40 



FIG. 10. CURVES SHOWING THE EFFECT OF GRADUAL CHANGE OP SECTION 
THROUGH 2-INCH GLOBE VALVE 

effect on the amount of head lost. This suggests that the lost head in 
a small globe valve is caused more by the form or shape of the passage- 
way at exit from the valve than by the form of the passages through the 
valve. Other valve openings and other modifications of the passage- 
ways, however, may give better results. 

In the case of angle valves the loss of head is not a minimum for 
the greatest valve opening as is shown in Table 1 and in Fig. 9. For 
the 2-in. angle valve the lost head is the same when the valve is only 
one-half open as it is when the valve is wide open, the velocity in the 
pipe for the two valve openings being the same, that is, the coefficient 



18 ILLINOIS ENGINEERING EXPERIMENT STATION 

of loss is the same for these two valve openings. When this valve is 
three-fourths open, however, the coefficient of loss is about 20 per 
cent less than when the valve is one-half open or wide open. The 1-in. 
globe valve caused a smaller amount of lost head when it was one-half 
and three-fourths open than it did when wide open, the velocity in the 
pipe being the same for each of the valve settings. The difference, 
however, between the coefficients of loss for these three valve openings 
is not large. The reason that the minimum loss of head in the angle 
valves occurs when the valve is about three-fourths open is probably 
because at this opening the water can flow through comparatively large 
openings all around the valve disc meeting with less abrupt changes of 
directions than when the valve is wide open. In the latter case there 
is much turbulent action due to the impact of the water against the bot- 
tom of the valve. As the valve opening decreases from the three-fourths 
open position, the greater resistance due to the narrowing passages 
causes the lost head to increase again. 

The assumption is sometimes made that for comparatively small 
valves of like type or kind the loss of head varies inversely with the 
diameter of the valve. For the larger valve openings this assumption 
is probably approximately true, but from the foregoing results and dis- 
cussion it would seem that at least for globe and angle valves the form 
or shape of the passages of the valve is a determining factor in the 
amount of head lost at the smaller valve openings. 

6. Earlier Experiments on Gate Valves. Among the first reliable 
published results on valves were those by Weisbach.* The largest 
gate valve used by Weisbach was a little less than two inches. Globe 
and angle valves, at least of modern construction, were not tested. 
Other experiments on gate valves have been reported by Magruderf 
on %-in., K-in., M-in., 1-in., and IM-in. gate valves, by FolwellJ on 
a 4-in. gate valve, by Kuichling^f on a 24-in. gate valve, and by J. Waldo 
Smith on a 30-in. gate valve. In Smith's experiments the 30-in. 
valve was located in a 42-in. pipe with increaser-shaped or Venturi- 
shaped approaches, and in Kuichling's experiments the valve was 
placed in one branch of a Y only a few feet from the section where the 
Y started to branch. The methods of determining the lost head in the 



* Mechanics of Engineering (Coxe's translation). 

t Engineering Record, Vol. XL, p. 78, 1899. 

t Engineering News, Vol. XLVII, p. 302, 1902. 

1 Trans. Am. Soc. Civ. Eng. Vol. XXVI, p. 439, and Vol. XXXIV. 

Trans. Am. Soc. Civ. Eng. Vol. XXXIV, p. 235 (p. 243), 1895. 



HYDRAULIC EXPERIMENTS 



19 



various experiments were also different. For these reasons it is obvi- 
ous that the results of these experiments are not directly comparable. 



TABLE 2 

VALUES OF THE COEFFICIENT OF Loss FOB GATE VALVES OF VARIOUS 
DIAMETERS DUE TO PARTIAL CLOSURE ONLY 



Ratio of Height 
of Opening to 
Diameter of 
Full Valve 
Orifice 


Weisbach 


Kuichling 


Smith 


Folwell 


This Bulletin 


2^-inch 
Diameter 


24-inch 
Diameter 


30-inch 
Diameter 


4-inch Diameter 


2-inch and 1-inch 


Parallel 
Sides 


Parallel 
Sides 


Parallel 
Sides 
Venturi- 
Shaped 
Ap- 
proaches 


Parallel 
Sides 


Wedge 
Shaped 


Parallel Sides 


2-inch 
Diameter 


1-inch 
Diameter 



















3/100 







950.0 










1/10 






128.0 











K 


98.0 




90.0 


72.3 


104 






M 


17.0 


22.7 


17.0 


16.8 


20.5 


18.45 


72.3 


N 


5.5 


8.63 


7.5 


6.19 


8.0 


7.0 1 


16. 1 


H 


2.1 
0.81 


3.27 
1 

1.09 


3.5 
1.5 


2.58 
1.22 


2.72 
1.5 


2.59 
1.2 1 


6.26 
2.5 1 


H 


0.26 


0.25 


0.50 


0.55 


0.66 


0.71 


1.10 


H 


0.07 


0.019 


0.19 


0.20 


0.16 


0.15 1 


0.70 1 


i 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 


0.00 



1 Interpolated from curve. 

In Table 2 are given the values of the coefficients of loss as obtained by 
the various experimenters mentioned previously, as well as the values 
obtained in the experiments herein reported. These values of the 
coefficients of loss are those due to partial closure of the valves only, 
that is, in excess of the loss of head caused by the valve when wide 
open. Smith's experiments are the only ones in which valve openings 
less than one-eighth were used. There is considerable chance for 
error in the results obtained for the very small valve openings, due 
chiefly to the uncertainty in securing the valve setting desired. Table 2 
indicates a rather close agreement in the coefficient of loss for all 
the gate valves having diameters of 2 in. or greater, and for valve 



20 



ILLINOIS ENGINEERING EXPERIMENT STATION 



openings of K or perhaps H and greater. The values for the 1-in. 
valve show a considerable increase in the lost head over that for valves 
of 2-in. diameter and greater. It is probable also that there is consid- 
erable variation in the smaller valves of any one type and size. 

7. Coefficients of Discharge for Gate Valves. In order to determine 
the rate of discharge through a pipe a partially closed valve has some- 
times been used. This requires the values of the coefficients of dis- 
charge of the valve for various valve openings since the rate of discharge, 
q, is found from the expression, cA^2gh, in which c is the coefficient 
of discharge, A the area of the valve opening, and h the difference in 
pressure heads on the two sides of the valve (lost head), velocity of 
approach being neglected. The average values of the coefficients of 
discharge for the 1-in. and 2-in. gate valves as found in the experi- 
ments reported in this bulletin are given in Table 3. The value of the 



TABLE 3 

EXPERIMENTAL VALUES OF THE COEFFICIENTS OF DISCHARGE FOR 
GATE VALVES 



Ratio of Height of Valve- 
Opening to Diameter of 
Full Valve-Opening 


Coefficient of Discharge 


Area of Valve-Opening 
Square Inch 


1-inch Valve 


2-inch Valve 


1-inch Valve 


2-inch Valve 


\i 


.48 


.88 


.195 


.826 


y* 


.67 


1.00 


.450 


1.80 


K 


,88 


1.12 


.660 


2.67 


i 


1.16 


1.70 


.785 


3.14 



coefficient varied somewhat with the velocity for any given valve open- 
ing. Because of the uncertainty of obtaining the exact valve setting 
desired and the corresponding uncertainty in the area of the valve 
opening, the values of the coefficients of discharge given in Table 3 
cannot be considered as refined determinations. 

It will be noted that the coefficient of discharge increases directly 
with the valve opening for each of the gate valves for a range of valve 



HYDRAULIC EXPERIMENTS 21 

openings of 34 to Y or perhaps greater. The more the valve is opened 
the greater is the velocity of approach toward the valve and since the 
velocity of approach is not considered in the calculation of the coeffi- 
cient of discharge the value of the coefficient increases with the valve 
opening. The coefficient of discharge for the valves used by Kuichling 
and Smith decreased slightly until the valve was about one-fourth open 
and then increased rapidly for further openings of the valve. Gibson 
with a 2j/2-in. flat disc stop valve found nearly a constant coefficient 
of discharge of 0.80. These variations in the coefficients of discharge 
are not surprising considering the wide range of conditions covered by 
the experiments. They suggest, however, that if gate valves are to 
be used for determining the rate of discharge in pipes with reasonable 
accuracy much more experimenting is required, or better, where it is 
possible, experiments should be performed under sendee conditions to 
calibrate the particular valve to be used. 

8. Summary. The following brief summary is given as applying 
to 1-in. and 2-in. valves of the three kinds tested (gate valves, globe 
valves, and angle valves) with valve settings ranging from one-fourth 
open to wide open. 

(1) The loss of head caused by small valves varies as the 
square of the velocity in the pipe for all the valve openings; hence 
the lost head may be expressed as a constant times the velocity head 

. ., . (j mv z \ 
in the pipe, ^/i = j. 

(2) When wide open a globe valve causes more than twice as 
much loss of head as an angle valve of the same size, while a gate 
valve causes much less loss of head than either a globe or an angle 
valve, the velocity in the pipe being the same in the three cases. 

(3) The loss of head for an angle valve is somewhat less when 
about three-fourths open than when wide open, the velocity in the 
pipe being the same in each case. 

(4) The loss of head for each valve, as the valve is closed from 
a wide-open position, varies comparatively little with the valve 
opening until the valve is at least one-half closed. As further 
closure takes place the loss of head of the globe valves and gate 
valves increases rapidly and is considerably larger than that of the 
angle valves. 

(5) The form or shape of the passageways through a globe or 
angle valve has a large influence on the loss of head for the small 



22 ILLINOIS ENGINEERING EXPERIMENT STATION 

valve openings. The portion of the passageways in which the form 
seems of greatest importance is in the exit from the valve rather 
than in the passageways leading to the valve disc or seat. On 
account of the influence of the form or shape of the valve no law 
giving the relation of the lost head to the diameter of the valve can 
be stated for valve settings less than five-eighths open. For larger 
valve openings than this, the lost head seems to vary approximately 
inversely as the diameter. 

(6) The use of the lost head through a partially closed valve 
as a means of determining the flow can be only a very rough method 
of measurement unless the particular valve to be used is calibrated 
under service conditions. Even then the difficulty in obtaining 
the desired valve setting may introduce considerable uncertainty 
in the results. 



PART II 

THE FLOW OF WATER THROUGH SUBMERGED 
ORIFICES 

BY FRED B SEELY 
ASSISTANT PROFESSOR OF THEORETICAL AND APPLIED MECHANICS 



CONTENTS 
PART II 

THE FLOW OF WATER THROUGH SUBMERGED 
ORIFICES 

PAGE 

IV. INTRODUCTION 27 

9. Preliminary . . . ' . 27 

10. Acknowledgment 28 

V. APPARATUS AND METHOD OF EXPERIMENTING .... 29 

11. Orifices - 29 

12. Tank Used and Method of Experimenting .... 30 

13. Method of Calculating the Coefficient of Discharge . 33 

VI. EXPERIMENTAL RESULTS AND DISCUSSION 34 

14. Coefficients of Discharge 34 

15. Results Obtained by Earlier Experimenters .... 37 

16. Comparison with Discharge into Air 39 

17. Summary , 40 



25 



LIST OF FIGURES 

NO. PAGE 

11. Tank Used and Arrangement of Apparatus 31 

12. Diagrams Showing Values of Coefficients of Discharge of Circular Sub- 

merged Orifices for Various Velocities 34 

13. Diagrams Showing Values of Coefficients of Discharge of Square Sub- 

merged Orifices for Various Velocities 34 

14. Diagrams Showing Values of Coefficients of Discharge of Rectangular Sub- 

merged Orifices for Various Velocities . . 35 

15. Curve Showing the Relation between Coefficient of Discharge for Circular 

Orifice and Diameter of Orifice 36 

16. Curve Showing the Relation between Coefficient of Discharge for Square 

Orifice and Side of Orifice 36 

17. Curve Showing the Relation between Coefficient of Discharge of Rectan- 

gular Orifice and Short Side of Orifice (other Side being Six Inches, in 
Each Case) .".......' 36 

18. Curves Showing Relation between Coefficient of Discharge and Area of 

Orifices 37 



LIST OF TABLES 

4. List of Orifices Used 29 

5. Values of Coefficient of Discharge for Submerged Orifices for Velocities 

from One-half to Five Feet per Second 35 

6. Results Obtained by Earlier Experimenters on Submerged Sharp-edged 

Orifices 38 



26 



HYDRAULIC EXPERIMENTS 27 



PART II 

THE FLOW OF WATER THROUGH SUBMERGED 
ORIFICES 



IV. INTRODUCTION 

9. Preliminary. Part II of this bulletin presents the results of 
experiments on submerged sharp-edged orifices of various shapes and 
sizes discharging under moderately low and under very low heads. 
The orifices used were of three shapes, circular orifices with diameters 
from 1 in. to 6 in., square orifices with sides from K in. to &A in., and 
rectangular orifices having one side range from Y* in. to 2 in., the other 
side being 6 in. in each case. The coefficient of discharge is given for 
each orifice for a velocity range of approximately ^A ft. per sec. to 
4 ft. per sec. This range corresponds roughly to a range of head on 
the orifice of 0.006 ft. to 0.08 ft. 

Considerable experimenting has been done on orifices discharging 
into air, particularly on sharp-edged circular orifices of rather small size 
although the results are somewhat discordant. Comparatively little 
experimental work, however, has been carried out on submerged orifices. 
While the orifice has lost some of its importance as a water measuring 
device due to the development of other methods, it is, nevertheless, of 
importance to determine how the rate of discharge is affected by the 
shape and the size of the orifice and also by the head on the orifice, 
particularly the effect of very low heads which the submerged orifice 
makes possible. 

The submerged orifice may be of particular importance in cases 
which require the measurement of water with as small a loss of head as 
possible as, for example, in determining the discharge from a water 
turbine when operating under a low head. The decrease in the avail- 
able head on the turbine made necessary by the proper setting of a weir 
may be an important factor in the installation. 

There is a feeling among some engineers that the importance of 
the so-called standard orifice (sjiarp edges, complete contraction without 
velocity of approach, etc.) has been over-emphasized and that beveled- 
edged orifices are better adapted at least to conditions where the orifice 
may be obstructed and the edge soon worn off, as, for example, in 
measuring the water supplied to water wheels through flume or bulk- 



28 ILLINOIS ENGINEERING EXPERIMENT STATION 

head openings. There exist, no doubt, some grounds for this feeling. 
A sharp edged orifice (an opening in a thin plate), however, is subject 
to less variation in its construction than a beveled-edged orifice. This 
fact is of considerable importance where accuracy is essential. It is 
felt that the submerged orifice, both beveled-edged and sharp-edged, 
is worthy of more attention than has been accorded it. 

10. Acknowledgment. The experimenting was done in the Hyd- 
raulic Laboratory of the University of Illinois. Some of the results 
herein presented have been taken from the theses of W. R. ROBINSON 
of the class of 1906 and G. D. PHILLIPS of the class of 1907, and some 
of the results also, particularly at the low heads, have been taken 
from a second thesis presented by Mr. Robinson in 1909. All the 
thesis work was conducted under the direction of PROFESSOR ARTHUR 
N. TALBOT. The careful way in which this preliminary experiment- 
ing was done has made the results of the theses of much value. Dur- 
ing 1914 and 1915 the writer spent considerable time in checking the 
results of the theses work and extending certain parts of the investi- 
gation. 



HYDRAULIC EXPERIMENTS 



29 



V. APPARATUS AND METHOD OF EXPERIMENTING 

11. Orifices. The orifices used were of three different shapes. 
Four of the orifices were circular with diameters of 1 in., 2 in., 4 in., 
and 6 in. Five were square with sides of % in., 1 in., 2 in., 4 in., and 
5K in. Three were rectangular with dimensions of % in. by 6 in., 
1 in. by 6 in., and 2 in. by 6 in. In each case the orifice was formed 
in a cast iron plate H in. thick and lO^ in. in diameter, a sharp edge 
being formed by beveling at 45 degrees. Except for a few small nicks 
the edges were sharp and the areas closely true to shape. The dimen- 
sions of the orifices were carefully determined (except for the 1-in. 
circular orifice) by an inside micrometer for dimensions greater than 
1 in. and inside screw calipers for dimensions less than 1 in. A list of 
the orifices used and the areas as determined from the measured dimen- 
sions are given in Table 4. The 1-in. circular orifice was broken before 



TABLE 4 
LIST OF ORIFICES USED 



Form of Orifice 


Nominal Size 


Measured Area 
square feet 




1 in. diam. 


not measured 


Circular 


2 in. diam. 
4 in. diam. 


0.0219 
0.0883 




6 in. diam. 


0.1967 




J^ in. by H in. 


0.001735 




1 in. by 1 in. 


0.00698 


Square 


2 in. by 2 in. 


0.0279 




4 in. by 4 in. 


0.1109 




5J3 in. by 5^ in. 


0.2105 




J^ in. by 6 in. 


0.0206 


Rectangular 


1 in. by 6 in. 


0.0418 




2 in. by 6 in. 


0.0838 



its dimensions were taken so that the nominal diameter (1 in.) has 
been used in the calculations. There may be some error, therefore, 
in the results for this orifice. 



30 ILLINOIS ENGINEERING EXPERIMENT STATION 

12. Tank Used and Method of Experimenting. The same tank 
was used in all the experiments, the dimensions and general arrange- 
ment of which is shown in Fig. 11.* The tank was divided into two 
compartments by a vertical partition in which the orifice was placed, 
holding the orifice in a vertical plane. 

The water coming from the laboratory standpipe was supplied 
to the tank through a 6-in. supply pipe and also through a M~ m - 
pipe, the latter making possible a finer adjustment in maintaining a 
constant head. After passing through baffle boards the water flowed 
through the orifice and finally left the downstream compartment by 
passing out through small openings in the end of the tank, the flow 
through which was regulated by placing stoppers in some of the holes. 
These holes were arranged in two narrow portions in the end of the 
tank, one near each side of the tank, and the stoppers were arranged 
so as to give nearly a uniform distribution from each of the two sets of 
openings. This arrangement, it was found, helped to maintain steady 
conditions. 

The quantity of water discharged was determined by weighing for 
the small discharges and by measuring in a pit for the larger discharges. 
The pit was about 6 ft. deep, and 7.995 ft. in diameter. The value 
for the diameter is the average of a large number of readings of a 
micrometer attached to a rigid stick. The rise in the pit was deter- 
mined by a vertical graduated rod which could be read directly to 
0.02 ft. and to 0.004 'ft. by estimating. A float was attached to the 
bottom of the rod and a still basin was provided. The water was 
wasted into another pit through a movable spout until the surface 
of the water in the measuring pit became fairly still so that an accurate 
reading of the rod could be taken. A hook gage was used to test the 
accuracy of the float and rod. At the end of the experiment the water 
was again wasted in the same manner. A calibrated stop watch gave 
the time corresponding to the rise in the pit. 

The head causing flow through the orifice is the difference in the 
levels of the water surfaces in the two compartments of the tank. 
This head was measured in nearly all the experiments by means of hook 
gages. These gages were read directly to 0.001 ft. and to 0.0005 ft. 
by estimating. Vertical 2-in. pipes attached toward the bottom of 
the tank served as still basins for the hook gages. The level of the 
water in the upstream compartment was determined by the use of one 



*A view of the tank is shown in Fig. 5 of Bulletin No. 96 of the Engineering Experiment Station 
of the University of Illinois. 



HYDRAULIC EXPERIMENTS 



31 








u '< TO" 




\J 






\\ a 

l| Measuring Pif 
\\ 
II 
II 

U 




Lower Floor tine --^ 



FIG. 11. TANK USED AND ARRANGEMENT OF APPARATUS 



32 ILLINOIS ENGINEERING EXPERIMENT STATION 

hook gage only, while two gages were used on the downstream com- 
partment in the earlier experiments. It was found, however, that for 
the lower heads the two gages gave practically the same result, while 
for the higher heads the gage nearer the partition gave less fluctuation. 
For these reasons and because of less difficulty in getting simultaneous 
readings of only two gages, it was decided to take readings with one 
gage only on each compartment. 

Zero readings of the hook gages were obtained by reading the 
gages when the tank was nearly full and when no water was allowed 
to escape, the levels of the water surfaces in the two compartments 
then being the same. Zero readings were taken frequently during 
the experimenting. 

For most of the heads above 0.3 ft., the head was measured by 
two vertical peizometer glasses, one attached near the bottom of each 
compartment, the difference in readings of which (corrected for zero 
reading) gave the head to 0.001 ft. These two methods overlapped 
somewhat so that certain heads were measured by both methods. 

Leakage from the tank and from the measuring pit was determined 
several times during the progress of the experimenting and was found 
to be negligible. 

An experiment or run consisted of the following: A sufficient 
number of stoppers was removed from the end of the tank to give the 
desired discharge and the inflow through the 6-in. and %-in. pipes 
was then adjusted until the difference in levels of the water surfaces 
in the two compartments of the tank became constant. The M-in. 
supply pipe was used to make^the final adjustment of the head and to 
hold the head constant throughout the experiment. After obtaining 
a constant head, the waste pipe'shown in Fig. 11 was pulled from beneath 
the discharge pipe, thus allowing the water to discharge into the meas- 
uring pit until the rise in the pit was sufficient to allow its measurement 
without appreciable error and also to allow time for an accurate meas- 
urement of the head. The head was taken as an average of from two 
to ten readings of the hook gages, the larger number being necessary 
with the higher velocities on account of the greater fluctuations of the 
water levels due to the more turbulent conditions of the water, espe- 
cially in the downstream compartment. Each experiment was repeated, 
as a rule, three times, although in some cases as many as eight or ten 
runs were made. 



HYDRAULIC EXPERIMENTS 33 

13. Method of Calculating the Coefficient of Discharge. The head, 
h, causing flow through the orifice is the difference in the levels of the 
water surfaces in the_two compartments of the tank. The ideal rate 
of discharge is A ^J2gh in which A is the area of the orifice in square 
feet and g is the acceleration due to gravity in feet per second per second ; 
hence the coefficient of discharge, c, is found from, 



where q is the measured rate of discharge in cubic feet per second, as 
determined from the measured weight or volume discharged and the 
corresponding time. 



34 



ILLINOIS ENGINEERING EXPERIMENT STATION 



VI. EXPERIMENTAL RESULTS AND DISCUSSION 

14. Coefficients of Discharge. Fig. 12, 13, and 14 show the 
experimental values of the coefficients of discharge for the various 
orifices tested. Each plotted point represents the average of from two 
to ten experiments at practically the same head. It will be noted that 







/ a 3 4 

Velocity through Orifice -ft per sec. 

FIG. 12. DIAGRAMS SHOWING VALUES OF COEFFICIENTS OF^DISCHARGE 
OF CIRCULAR SUBMERGED ORIFICES FOR VARIOUS VELOCITIES 



.65 
.60 









.70 

| ' 

65 
.60 






0.5 



/ 2 3 4 

Velocity throw/7 Orifice - ft per sec 

FIG. 13. DIAGRAMS SHOWING VALUES OF COEFFICIENTS OF DISCHARGE OF 
SQUARE SUBMERGED ORIFICES FOR VARIOUS VELOCITIES 



S 



HYDRAULIC EXPERIMENTS 



35 




^*j 



60 



0.5 



^ 3 4 

Ve/oc/ty through Orifice -ft per sec. 



FIG. I&. DIAGRAMS SHOWING VALUES OF COEFFICIENTS OF DISCHARGE OF 
RECTANGULAR SUBMERGED ORIFICES FOR VARIOUS VELOCITIES 

for any given orifice the coefficient is constant for the whole range of 
velocity used in these experiments which in most of the cases is about 
% ft. per sec. to 4 or 5 ft. per sec. This velocity range corresponds 
roughly to a range in head of 0.008 to 0.08 ft. and as may be expected 
the values of the coefficient show the greatest variation at the very 
low heads. 



TABLE 5 

VALUES OF COEFFICIENT OF DISCHARGE FOR SUBMERGED ORIFICES FOR VELOCITIES 
FROM ONE-HALF TO FIVE FEET PER SECOND 



Kind of Orifice 


Nominal Size 


Coefficient of Discharge 




1 in. diameter 


0.6351 




2 in. diameter 


0.615 


Circular 








4 in. diameter 


0.600 




6 in. diameter 


0.600 




% in. by ^ in. 


0.620 




1 in. by 1 in. 


0.610 


Square 


2 in. by 2 in. 


0.610 




4 in. by 4 in. 


0.605 




5H in. by 5% in. 


0.600 




^ in. by 6 in. 


0.635 


Rectangular 


1 in. by 6 in. 


0.635 




2 in. by 6 in. 


0.635 



1 Probably somewhat in error since diameter was not measured; nominal diameter used in 
calculations. 



36 



ILLINOIS ENGINEERING EXPERIMENT STATION 



Table 5 and Fig. 15, 16, and 17 show how the coefficient of dis- 
charge for the orifices of any given shape varies with the diameter or 




^ 3 456 

D/ctrr?efer of C/rcu/ar Orifices- in. 

FIG. 15. CURVE SHOWING THE RELATION BETWEEN COEFFICIENT OF 
DISCHARGE FOR CIRCULAR ORIFICE AND DIAMETER OF ORIFICE 




FIG. 16. 



3 4 S 6 

5ide of Square Orifices - in 

CURVE SHOWING THE RELATION BETWEEN COEFFICIENT OF DIS- 
CHARGE FOR SQUARE ORIFICE AND SIDE OF ORIFICE 




as 



i 2 3 4 

Vertical Side of Reef angu Jar Orifices -in. 



FIG. 17. CURVE SHOWING THE RELATION BETWEEN COEFFICIENT OF DIS- 

CHARGE OF RECTANGULAR ORIFICE AND SHORT SIDE OF ORIFICE 

(OTHER SIDE BEING Six INCHES IN EACH CASE) 

side of the orifice, while from Fig. 18 a comparison may be made between 
the coefficients of discharge for the different shaped orifices on the 
basis of their areas. These figures show that the coefficient of discharge 
for circular and square orifices decrease as the size increases until an 
area of 8 or 10 square inches is reached after which the coefficient has 
a constant value of not far from 0.60. This indicates that complete 
contraction does not take place with the smaller orifices. Because of 
the uncertainty of the exact diameter there is some doubt, however, 
concerning the correct value for the 1-in. circular orifice. It will be 
noted also that the coefficient of discharge for the rectangular orifices 



HYDRAULIC EXPERIMENTS 



37 



.65 




4 6 8 10 tf 14 16 16 ^O 
Area of Orifice -sq. in. 



E6 ^Q 3O 3^ 



FIG. 18. CURVES SHOWING RELATION BETWEEN COEFFICIENT OF 
DISCHARGE AND AREA OF ORIFICES 

remain constant for the range of areas used in these experiments and 
that its value is larger than that for circular and square orifices of the 
same area. Fig. 18 indicates furthermore that as the area of the orifices 
decreases below 8 sq. in., the coefficient of discharge for circular orifices 
increases faster than that for square orifices. These observations 
suggest that the longer side of the rectangular orifices has a controlling 
influence in determining the rate of discharge for a given head and 
that the corners of a small square orifice are inefficient in discharging 
water as compared with the form of a circular orifice of the same area. 

15. Results Obtained by Earlier Experimenters. In order to com- 
pare the results given in this bulletin with those of earlier investigations 
and to extend the study to include higher heads and velocities, the 
results given in Table 6 have been condensed from available published 
data. It will be noted that the results are not entirely concordant, 
but considering the different arrangements and methods of measuring 
the head and the rate of discharge, the results show a very good agree- 
ment. The low value of the coefficient of discharge found by Francis 
is due no doubt to the fact that the rate of discharge was measured 
over a weir on which the head was rather small. From Table 6 it will 
be seen that in some of the earlier investigations the coefficient of 
discharge increased slightly with the head while in others the coeffi- 
cient decreased, and in still others it showed no systematic change. 
In all cases the value of the coefficient of discharge is not far from 
0.60. The small square orifice (1.2 in. by 1.2 in.) used by Hamilton 
Smith gave a slightly larger coefficient than the circular orifice with 
a diameter of 1.2 inches. This result is the reverse of that found in 
the experiments described in this bulletin. The values also of the 
coefficient of^discharge for circular and square orifficesjas found by 



38 



ILLINOIS ENGINEERING EXPERIMENT STATION 



TABLE 6 

RESULTS OBTAINED BY EARLIER EXPERIMENTERS ON SUBMERGED 
SHARP-EDGED ORIFICES 



Circular Orifices 


Square Orifices 


Source 


Diam- 
eter 
inches 

d 


Head 

feet 

h 


Coeffi- 
cient 
of 
Dis- 
charge 
c 


Source 


Dimen- 
sions 
inches 


Head 
feet 

h 


Coeffi- 
cient 
of 
Dis- 
charge 
c 


Francis 


1.22 


1.024 
1.324 
1.490 
1.499 
1.514 


.592 
.592 
.592 
.593 
.591 


Hamilton Smith, Jr. 


0.6 by 0.6 


0.35 
2.21 
4.06 


.6201 
.6092 
.6068 


Hamilton Smith, Jr. 


1.2 by 1.2 


0.207 
0.410 
0.771 
1.52 
2.32 
3.11 
3.95 


.6117 
.6091 
.6053 
.6055 
.6040 
.6052 
.6048 


Hamilton Smith, Jr. 


0.6 


0.437 
2.16 
4.08 


.6183 
.6041 
.6016 


Hamilton Smith, Jr. 


1.2 


0.250 
0.648 
0.985 
1.51 
2.00 
2.58 
2.99 
3.57 
3.97 


.6048 
.6027 
.6025 
.6006 
.6006 
.5997 
.5989 
.5987 
.5992 


Ellis 


12 by 12 


2.32 
3.92 
7.99 
11.58 
14.31 
16.22 
18.45 


.600 
.602 
.606 
.605 
.611 
.606 
.606 


Ellis 


12.0 


2.60 
4.71 
6.41 
8.10 
8.80 
12.09 
14.25 
16.29 
18.66 


.607 
.590 
.606 
.599 
.600 
.600 
.601 
.602 
.599 


Balch 


12 by 12 


0.363 
0.750 
0.771 
0.826 
0.905 
1.134 
1.371 
2.097 
2.636 
3.220 
3.975 


. 5940 
.5940 
. 5932 
.5982 
.5950 
.5960 
.5970 
.6056 
.6105 
.6095 
.6148 


Balch 


12.0 


0.145 
0.469 
0.851 
1.254 
1.612 
2.012 
2.421 
2.949 
3.410 
4.015 


.5909 
.5902 
.5912 
.5993 
.5921 
.5924 
.5954 
.5967 
.6006 
.6054 


Stewart 


48 by 48 
(3. 72 in. 
thick) 


.05 
.10 
.15 
.20 
.25 
.30 


.626 
.608 
.605 
.605 
.606 
.610 


Rectangular Orifices 


Hamilton Smith, Jr. 


0.6 by 3.6 


0.614 
1.63 
2.77 


.6219 
.6207 
.6188 



HYDRAULIC EXPERIMENTS 39 

Hamilton Smith are slightly less than those herein reported in Table 5. 
Omitting the values as given by Francis it will be observed that there 
is very little difference between the coefficients for the small and the 
large orifices, the value of the coefficient varying only slightly from 
0.60. From the results obtained in the present investigation as given 
in Table 5 and in Fig. 12, 13, and 14, it will be seen that the coefficient 
varies more with the size of the orifice than is shown by the results of 
the earlier experiments, as given in Table 6. 

It will be observed also that the coefficient of discharge for the 
rectangular orifice used by Hamilton Smith is somewhat smaller than 
that herein reported. It may seem that the diverging sides of the 
orifices used in the experiments reported in this bulletin (orifice plate 
M-in. thick) would form a diverging mouthpiece, particularly in the 
case of the smaller orifices, but experiments* on diverging mouth- 
pieces have shown that a mouthpiece having a total angle of divergence 
of 90 degrees has very little, if any, effect on the rate of discharge. 

16. Comparison with Discharge into Air. The experiments on 
sharp-edged orifices with discharge into air are more numerous than 
for submerged discharge. The experiments of Bilton and to a less 
degree those by Judd and King, and those by Mair and by Ellis indicate 
that there is a critical head for each circular orifice above which the 
coefficient remains constant. Bilton concludes that "circular orifices 
of 2>-in. diameter, and over, under heads of 17 in., and over, have a 
common coefficient of discharge lying between 0.59 and 0.60 but which 
is probably about 0.598 (subject to the head being not less than 2 or 
3 diameters)." The results of the experiments of Hamilton Smith, as 
is well known, indicate that the coefficient of discharge gradually 
decreases as the size of the orifice increases, and also decreases as the 
head increases until at a head of 100 ft. all orifices, regardless of the 
size or the shape, have a common coefficient of discharge. 

The results of the experiments on submerged orifices herein reported 
seem to indicate, as previously noted, that orifices having diameters 
greater than about 2^ in. (or sides, if square) have a common co- 
efficient of discharge which is very close to 0.60. There seems, how- 
ever, to be no evidence of a critical head since the coefficient remains 
constant for the whole range of head used, nor is there evidence of a 
critical head in the results obtained by earlier experimenters on sub- 
merged orifices as given in Table 6. 



*"The Effect of Mouthpieces on the Flow of Water Through a Submerged Short Pipe." 
Univ. of 111. Eng. Exp. Sta., Bui. 96, 1917. 



40 ILLINOIS ENGINEERING EXPERIMENT STATION 

From a study of the experimental results on orifices with discharge 
into air it is believed that the coefficient of discharge for submerged 
orifices are the same as those for discharge into air for the same heads 
and sizes and shapes (except for very small heads). It is doubtful if 
the statement sometimes made, namely, that the coefficient of discharge 
for submerged orifices is about one per cent less than that for free dis- 
charge, is justified. 

17. Summary. The following brief summary is given as applying 
to submerged sharp-edged orifices for velocities from K to 5 ft. per sec. 

(1) The coefficient of discharge for a circular, a square, or 
a rectangular submerged orifice does not vary with the velocity. 

(2) Circular and square submerged orifices having areas 
greater than about 10 sq. in. have a common coefficient of dis- 
charge varying but little from 0.60. 

(3) Rectangular submerged orifices having one side from 3 to 
12 times the other side have a constant coefficient of discharge 
which is larger than that for circular and square orifices of the 
same size, particularly for the larger areas, at least up to a size 
of 12 sq. in. 

(4) The flow of water through submerged sharp-edged ori- 
fices is very nearly the same as that for the same kind of orifices 
with discharge into air, provided the head is not less than 2 or 3 

. diameters when the discharge is jnto air. 



PART III 
FIRE STREAMS FROM SMALL HOSE AND NOZZLES 

BY VIRGIL R FLEMING 

ASSISTANT PROFESSOR OF APPLIED MECHANICS 



CONTENTS 

PART III 
FIRE STREAMS FROM SMALL HOSE AND NOZZLES 

PAGE 

VII. INTRODUCTION . . ... ... ... , . . . . . 45 

18. Scope of Experiments . . . . . . . . .45 

19. Acknowledgment '. . . . 46 

VIII. APPARATUS AND METHOD OF EXPERIMENTING .... 47 

20. Hose and Nozzles . . ., . . . . . . . . . 47 

21. Method of Experimenting ........ 48 

IX. EXPERIMENTAL RESULTS AND DISCUSSION . . . . . 49 

22. Results from Freeman's Experiments . . 49 

23. Experimental Data .49 

24. Friction Factors . ... . . . ... 53 

25. Coefficients of Discharge 54 

26. Height and Horizontal Distance of Jets . ... . 55 

27. Effect of Cylindrical Tip 56 

28. Requirements for Temporary Fire Protection for the 

Interior of Buildings . 57 

29. Summary ......... 59 



43 



LIST OF FIGURES 

NO. PAGE 

19. Longitudinal Sections of Nozzles Tested . ... . . . . . . 47 

20. Cross-section of Piezometer Coupling 48 

21. Diagram Showing Friction Factors in Rubber-lined and Unlined Hose . 53 

22. Diagram Showing Coefficients of Discharge of Nozzles 54 



LIST OF TABLES 

7. Freeman's Results for 1-in., 1^-in. and l}4-in. Nozzles Attached to 

2^-in. Hose . . '. . . . . 50 

8. Results of Experiments at University of Illinois with y\ 6- m -> Ke- m -> a ^d 

in. Nozzles Attached to 1 3^-in. Hose 51 



44 



HYDRAULIC EXPERIMENTS 45 

PART III 
FIRE STREAMS FROM SMALL HOSE AND NOZZLES* 



VII. INTRODUCTION 

18. Scope of Experiments. Part III presents the results of experi- 
ments on IK-in. hose and nozzles. Both rubber-lined hose and un- 
lined linen hose were used. Three sizes of conical nozzles were tested, 
the diameters of the nozzle openings being ^fe in., Ke in., and K in. 

The loss of head in the hose due to friction and the corresponding 
friction factor are given for each hose for a range in velocity from 
about 4 to 8 ft. per sec. The coefficient of discharge for each nozzle 
is recorded for a range in pressure at the base of the nozzle from about 
10 to 85 Ib. per sq. in. The height and the horizontal distance which 
the jets reached are also recorded. The influence of a cylindrical tip 
on a nozzle is brought out and some discussion is given concerning 
the quantity of water required for temporary fire protection for the 
interior of buildings. 

The importance of adequate fire protection has become so well rec- 
ognized that most buildings, even those of moderate size, are equipped 
with some sort of fire apparatus for immediate service in case of fire in 
the interior of the building and until the city fire department arrives. 
The ordinary water buckets and portable chemical fire extinguishers 
have in a large measure been supplemented with small fire hose. Few 
data are available concerning the hydraulics of small fire streams. 
Many inquiries concerning the discharge from small nozzles and the 
loss of head in small hose led to the tests which are herein described. 
The tests were undertaken with the object of acquiring data and putting 
the results into so workable a form that it would be easy to compute 
the quantity of water delivered by a nozzle of the size ordinarily used 
in the fire protection of the interior of buildings or to compute the 
pressure necessary in the mains to give an effective fire stream from 
such nozzles, and also to throw some light upon the quantity of water 
which would be considered sufficient for temporary protection. 

* The experiments used in Part III of this Bulletin were reported in the Proceedings of 
the Fifth Meeting of the Illinois Water Supply Association, p. 170, 1913. 



46 ILLINOIS ENGINEERING EXPERIMENT STATION 

19. Acknowledgment. The experiments here used were con- 
ducted at the University of Illinois under the direction of the writer 
by E. O. KORSMO and A. B. NEININGER of the class of 1911 as thesis 
work. Much credit is due them for the care and thought given the 
problem and the thoroughness with which they did their work. The 
water for the experiments was drawn from the University mains. 
The experiments for determining the height and the horizontal dis- 
tance the jets would reach were conducted out of doors. The other 
experiments were carried on in the Hydraulics Laboratory. 



HYDRAULIC EXPERIMENTS 



47 



VIII. APPARATUS AND METHOD OF EXPERIMENTING 

20. Hose and Nozzks. Rubber-lined cotton hose and unlined 
linen hose having a nominal diameter of \^A in. were used, the length 
of the test section for determining the lost head being 50 ft. in each 
case. The hose taken was from the racks in the University buildings 
and is representative of hose of this size commonly in use. 

Three IJ-in. conical nozzles having different sizes of openings, 
as shown in Fig. 19, were tested. The first nozzle had a diameter of 




out smooth 



FIG. 19. LONGITUDINAL SECTIONS OF NOZZLES TESTED 



Me in. The second nozzle had a diameter of 0.428 in., which is ap- 
proximately KG in., and in compiling the tables, corrections were made 
so as to apply to a Ke-in. nozzle. The third nozzle had a diameter 
of Yz in. The Me-in. nozzle was 12 in. long while the other two were 
only 6 in. long (see Fig. 19). The Me-in. and the Ke-in. nozzles were 
rough on the interior surfaces, having been left just as ihey came 
from the molds, the prints of the sand core being plainly visible. 
The tips had been smoothed slightly by running a drill through the 



48 



ILLINOIS ENGINEERING EXPERIMENT STATION 



opening, but the cylindrical portion made by the drill was very short 
in both cases. The M-in. nozzle was made from a Ke-in. nozzle. The 
entire inner surface was machined smooth and a K-in. reamer was run 
through the opening making a cylindrical portion K in. long. 

21. Method of Experimenting. The loss of head was measured 
over a length of fifty feet of the hose by means of a differential mercury 
gage. The average pressure at a section of the hose was obtained with 
a piezometer connection or coupling of the Freeman type. A cross- 
section of one of these couplings is shown in Fig. 20. The discharge 




Openings, -3 of/a, 

Sec f /on fl-ft 

FIG. 20. CROSS-SECTION OF PIEZOMETER COUPLING 



through the hose when determining the lost head in the hose was meas- 
ured with a calibrated nozzle. When determining the coefficient of 
discharge for the nozzles the discharge was measured by weighing. 
The pressure at the base of the nozzle was measured with a calibrated 
pressure gage. 

The vertical heights attained by the streams were determined by 
means of a transit and the horizontal distances reached were found 
by measuring with a tape from stakes which were driven in the ground 
at frequent intervals and at known distances from the nozzle. 



HYDRAULIC EXPERIMENTS 49 



IX. EXPERIMENTAL RESULTS AND DISCUSSION 

22. Results from Freeman's Experiments. In 1888 John R. Free- 
man conducted an extensive series of tests upon 2M-in. fire hose and 
nozzles.* In general, Freeman arrived at the following conclusions: 
Smooth conical nozzles give coefficients of discharge as high as any 
other form of nozzle, the jets reach farther and the streams remain 
solid for greater distances than for any other form of nozzle of the 
same size of opening and with the same pressure at the base of the 
nozzle. For smooth conical nozzles IH or IH in. in diameter, a 
coefficient of discharge of 0.977 may be taken with great confidence 
that it will not be more than one-half of 1 per cent in error. The 
coefficient will be slightly larger for smaller nozzles. The nozzle 
makes a very convenient method of measuring water. The friction 
is but slightly more in smooth rubber-lined hose than in clean iron pipe 
of the same diameter. The friction in unlined linen hose is about 
two and one-third times as much as in smooth rubber-lined hose. 
A hose elongates from 2 per cent to 5 per cent with a pressure of 50 
Ib. per sq. in. This elongation produces a sinuosity which increases 
the loss of head about 6 per cent. Care should be exercised that 
there is no abrupt change of section in the hose couplings and that 
no washers or gaskets are so left as to impede the flow of water. 

It is frequently recommended that a 250 gal. per min. fire stream 
be used in business districts, while a 175 or a 200 gal. per min. stream 
may be used in a residential district. These discharges correspond to 
a nozzle pressure of 40 to 50 Ib. per sq. in., and a hydrant pressure of 
80 to 110 Ib. per sq. in. These values refer to outside service. Table 
7 gives data for 2M-in. hose and nozzles for three different sizes of 
nozzle openings taken from Freeman's results. This table is con- 
venient for making calculations for outside fire protection. 

23. Experimental Data. Table 8 gives the more important data 
of the experiments with hose and nozzles herein reported. Values are 
given for the pressures at the base of the nozzles, the discharges, the 
loss of head in the hose, and the vertical and horizontal distances reached 
by the jets. Other results discussed have been calculated from the 
data in this table. 



*" Experiments Relating to the Hydraulics of Fire Streams." Trans. Am. Soc. Civ. Eng., 
Vol. XXI, p. 304, 1889. 



50 



ILLINOIS ENGINEERING EXPERIMENT STATION 



TABLE 7 

FREEMAN'S RESULTS FOR I-IN. I^-IN. AND I^-IN. NOZZLES ATTACHED 
TO 2^-IN. HOSE 

1-iNCH NOZZLE 







Loss of Head in 
100 Feet of Hose 


Vertical 


Horizontal Distance 


Pressure 






Height of 




Base of 
Nozzle 


Discharge 


Rubber 
Lined 


Unlined 
Linen 


Jet for 
Good Fire 
Stream 


Jet for 
Good Fire 
Stream 


Extreme 
Drops at 
Level 














of Nozzle 


Lb. per 
sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


132 


5 


10 


35 


37 


77 


30 


161 


7 


15 


51 


47 


109 


40 


186 


10 


20 


64 


55 


133 


50 


208 


12 


25 


73 


61 


152 


60 


228 


15 


30 


79 


67 


167 


70 


246 


17 


35 


85 


72 


179 






NOZZLE 







Loss of Head in 
100 Feet of Hose 


Vertical 


Horizontal Distance 


Pressure 






Height of 




Base of 
Nozzle 


Discharge 






Jet for 
Good Fire 


Jet for 


Extreme 






Rubber 


Unlined 


Stream 


Good Fire 


Drops at 






Lined 


Linen 




Stream 


Level 














of Nozzle 


Lb. per 

sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


168 


8 


16 


36 


38 


80 


30 


206 


12 


25 


52 


50 


115 


40 


238 


16 


33 


65 


59 


142 


50 


266 


20 


41 


75 


66 


162 


60 


291 


24 


49 


83 


72 


178 j 


70 


314 


28 


57 


88 


77 


191 



HYDRAULIC EXPERIMENTS 



51 



NOZZLE 







Loss of Head in 
100 Feet of Hose 


Vertical 


Horizontal Distance 


Pressure 






Height of 




Base of 
Nozzle 


Discharge 






Jet for 
Good Fire 


Jet for 


Extreme 






Rubber 
Lined 


Unlined 
Linen 


Stream 


Good Fire 
Stream 


Drops at 
Level 














of Nozzle 


Lb. per 
sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


209 


12 


25 


37 


40 


83 


30 


256 


19 


38 


53 


54 


119 


40 


296 


25 


51 


67 


63 


148 


50 


331 


31 


63 


77 


70 


169 


60 


363 


37 


76 


85 


76 


186 


70 


392 


43 


88 


91 


81 


200 



TABLE 8 

RESULTS OF EXPERIMENTS AT UNIVERSITY OF ILLINOIS WITH % 6 -m., 
AND H-IN. NOZZLES ATTACHED TO 13-^-iN. HOSE 

% 6 -iNCH NOZZLE 







Loss of Head in 
100 Feet of Hose 


Vertical 


Horizontal Distance 


Pressure 
Base of 
Nozzle 


Discharge 






Height of 
Jet for 
Good Fire 
Stream 




Rubber 
Lined 


Unlined 
Linen 


Jet for 
Good Fire 
Stream 


Extreme 
Drops at 
Level 
of Nozzle 


Lb. per 

sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


12 


.7 


1.3 


28 


15 


53 


30 


15 


1.1 


1.9 


32 


18 


63 


40 


17 


1.5 


2.6 


34 


21 


71 


50 


19 


1.8 


3.2 


35 


23 


78 


60 


21 


2.2 


3.9 


36 


26 


84 


70 


23 


2.6 


4.5 


37 


28 


90 


80 


24 


2.9 


5.2 


38 


29 


96 


90 


26 


3.3 


5.9 


39 


30 


102 


100 


28 


3.7 


6.5 


40 


31 


107 



52 



ILLINOIS ENGINEERING EXPERIMENT STATION 



NOZZLE 







Loss of Head in 
100 Feet of Hose , 


Vertical 


Horizontal Distance 


T> pOQ|, r O 










Base of 
Nozzle . 


Discharge 


Rubber 
Lined 


Unlined 
Linen 


Jet for 
Good Fire 
Stream 


Jet for 
Good Fire 
Stream 


Extreme 
Drops at 
Level 
of Nozzle 


Lb. per 
sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


25 


2.8 


5.1 


23 


10 


45 


30 


30 


4.2 


7.7 


27 


13 


54 


40 


35 


5.6 


10.2 


30 


16 


63 


50 


39 


7.0 


12.8- 


32 


18 


70 


60 


43 


8.5 


15.3 


33 


20 


77 


70 


47 


9.8 


17.8 


34 


21 


84 


80 


50 


11.1 


20.3 


35 


23 


94 


90 


53 


12.7 


22.9 


36 


24 


99 


100 


56 


14.1 


25.5 


37 


25 


106 



NOZZLE 







Loss of Head in 
100 Feet of Hose 


Vertical 


Horizontal Distance 


Pressure 
Base of 
Nozzle 


Discharge 




Height of 
Jet for 
Good Fire 
Stream 




Rubber 
Lined 


Unlined 
Linen 


Jet for 
Good Fire 
Stream 


Extreme 
Drops at 
Level 
of Nozzle 


Lb. per 

sq. in. 


Gallons per 
minute 


Lb. per 
sq. in. 


Lb. per 
sq. in. 


Feet 


Feet 


Feet 


20 


33 


5.2 


9.5 


34 


15 


63 


30 


40 


7.7 


14.4 


37 


20 


79 


40 


46 


10.2 


18.8 


38 


25 


91 


50 


52 


12.8 


23.8 


39 


30 


102 


60 


57 


15.4 


28.5 


40 


33 


111 


70 


61 


18.0 


32.7 


41 


37 


120 


80 


65 


20.5 


38.4 


42 


40 


127 


90 


69 


23.0 


42.0 


43 


43 


134 


100 


73 


25.6 


47.0 


44 


46 


140 



HYDRAULIC EXPERIMENTS 



53 



24. Friction Factors. The curves of Fig. 21 show the friction 
factors for each kind of hose used and for velocities in the hose ranging 




m 



8 /O 

- ft per sec. 



FIG. 21. 



DIAGRAM SHOWING FRICTION FACTORS'IN ^RUBBER-LINED AND 
UNLINED HOSE 



from 4 to 8 ft. per sec. These curves cover the range of velocities 
which would be met in ordinary use. The friction factor / is computed 
from the formula 

h= d^g 

h = head lost in feet of water 
I = length of hose in feet 
d = diameter of hose in feet 

v = velocity of the water in the hose in feet per second 
g = acceleration due to gravity in feet per second per second 

The loss of head in the rubber-lined hose varies almost directly 
as the square of the velocity and is about the same as the loss of head 
in clean iron pipe of the same diameter. The friction factor for the 
unlined linen hose decreases as the velocity increases, or in other words 
the loss of head does not vary directly as the square of the velocity, 
the ratio of the lost head to the square of the velocity being larger for 
the lower velocities. The reason that the friction factor for unlined 
linen hose decreased more rapidly with the velocity than does that for 
rubber-lined cotton hose may be that the diameter of the unlined hose 



54 



ILLINOIS ENGINEERING EXPERIMENT STATION 



is increased more than that of the rubber-lined cotton hose by the 
increasing pressures which accompany the increasing velocities. This 
would make the value of d larger and the value of v smaller in the equa- 
tion for / than was actually used. It is probable, furthermore, that the 
increasing pressure decreases the roughness of the unlined linen hose 
more than it does for rubber-lined hose. In general the lost head in 
the unlined linen hose is about twice as great as in the rubber-lined 
cotton hose. If an average value of the friction factor (0.06) is used 
for the unlined linen hose, no great error will enter into the results 
under ordinary circumstances. The length of hose will ordinarily not 
be mose than 100 feet and for this length about 10 Ib. per sq. in. will 
be the maximum loss of head in the unlined linen hose under working 
conditions with nozzles giving streams up to K in. in diameter. An 
error as large as 10 per cent in the calculation of the loss of head in 
the hose would affect the nozzle pressure not more than one pound 
per square inch. 




O JO ^O 3O 4O 5O 6O 7O SO 9O 

Pressure a/ fiase of/Yozz/e- / per sq.in 
FIG. 22. DIAGRAM SHOWING COEFFICIENTS OF DISCHARGE OF NOZZLES 

While the loss of head in the unlined linen hose is about twice as 
great as the loss of head in the rubber-lined hose, the linen hose has 
several advantages. It is much lighter to handle, folds up in less space 
on the wall racks, costs only about 50 to 60 per cent of the cost of 
rubber-lined hose and, in an ordinary building, its life is much longer. 

25. Coefficients of Discharge. The coefficients of discharge for 
each of the three sizes of nozzles are given in Fig. 22 for pressures 



HYDRAULIC EXPERIMENTS 55 

at the base of the nozzle ranging from about 10 to 85 Ib. per sq. in. 
This range of pressures corresponds to a range in the velocity of the 
issuing jet from a minimum of about 35 ft. per sec. with the >-in. 
nozzle to a maximum of about 185 ft. per sec. with the Ke-in. nozzle. 
The coefficient of discharge is the ratio of the measured discharge to 
the ideal discharge. The measured discharge was weighed and the 
volume computed from the weights. The ideal discharge was com- 
puted from the formula 

q = A ij~2gh 

q = discharge in cubic feet per second. A = area of the opening of the 
nozzle in square feet, g = acceleration due to gravity in feet per 
second per second. h = pressure at the base of the nozzle in feet of 
water. The velocity of approach to the nozzle was negligible and 
was, therefore, not considered in the equation for the ideal discharge. 
The pressure at the base of the nozzles was measured with calibrated 
pressure gages. 

The coefficient of discharge for the Ke-in. and the 3^-in. nozzles 
is nearly constant for all pressures and averages 0.98. The coefficient 
is slightly lower than 0.98 for the Ke-in. nozzle at the higher pressures. 
The ^6-in. nozzle gives a coefficient of 0.95. The Y\ e-in. nozzle is 12 
inches long while the other two are only 6 inches long, and this greater 
length adds somewhat to the friction and lowers the coefficient of 
discharge for the ^fe-in. nozzle. 

The Me-in. and the Ke-in. nozzles were rough on the interior 
surfaces, having been left just as they came from the molds. The 
tips had been smoothed slightly by running a drill through the opening, 
but the cylindrical portion made by the drills was very short in each 
case and the nozzles gave streams which sprayed badly a short distance 
away. The 3^-in. nozzle was made from a Ke-in. nozzle. The entire 
inner surface was first machined out in hopes that it would prevent 
the spraying of the jet, but the nozzle gave a stream which appeared 
no better than before machining. Then a 1 jH*2-in. reamer and finally 
a M-in. reamer were run through the opening, each reducing the spray- 
ing. The >6-in. reamer made the cylindrical portion of the opening 
M-in. long, and the resulting nozzle gave a very good stream. An 
opening larger than M-in. could not be made in the nozzle because 
of the thinness of the walls. 

26. Height and Horizontal Distance of Jets. The heights and the 
horizontal distances reached by the jets from each of the three nozzles 



56 ILLINOIS ENGINEERING EXPERIMENT STATION 

used are given" in Table 8. As stated, the vertical heights were meas- 
ured by means of a transit and the horizontal distances were measured 
with a tape^from^stakes which were driven in the ground at frequent 
known space intervals. The observations were made when a moderate 
wind was blowing which interfered with the streams considerably. A 
stream was considered good for the distance in which practically all the 
water [would pass through a circle whose diameter was 18 inches. 
The~value was an arbitrary selection and the streams might be con- 
sidered by some as effective for greater distances than those given in 
Table 8. The streams, however, beyond the sections chosen, diverged 
rapidly and the selection of a circle larger than 18 inches would have 
added but a few feet to the distances given in Table 8 in any case. 

27. Effect of Cylindrical Tip. The tests show clearly the impor- 
tance of a smooth cylindrical opening at the tip of the nozzle. A com- 
parison of the results of the tests on the Ke-in. and the M-in. nozzles 
for vertical heights and horizontal distances of the jets will show this 
difference. In the case of the Ke-in. nozzle with a pressure of 30 Ib. 
per sq. in. at the base of the nozzle the vertical height of the jet was 
27 ft. as compared with 37 ft. for the ^-in. nozzle for the same pressure. 
Likewise the horizontal distance reached with the Ke-in. nozzle was 
13 ft. as compared with 20 ft. with the K-in. nozzle. Similar com- 
parisons may be made for other pressures at the base of the nozzle. 
The appearance of the jets showed a much greater difference than 
the data would indicate. It must be remembered that the two nozzles 
were alike and gave streams which appeared to be the same before 
one was reamed out to a larger size. 

It will be noted also that, in the case of the % e-in. nozzle for a 
pressure of 30 Ib. per sq. in. at the base of the nozzle, the vertical and 
horizontal distances reached by the stream were respectively 32 and 
18 ft., which indicate that the improvement in the carrying capacity 
of the K-in. nozzle over that of the Ke-in. nozzle was not due to the 
smoother condition of the interior surface of the M-in. nozzle, but 
rather to the effect of the cylindrical tip. The condition of the interior 
surface of the nozzle to within one-half inch of the end does not seem 
to affect appreciably either the quantity of discharge or the quality 
of the stream. 

It seems important, therefore, that the tip of the nozzle should 
be reamed out for a distance of at least % in. in order to obtain a good 
fire stream. It is probably true also that for nozzles somewhat larger 



HYDRAULIC EXPERIMENTS 57 

than those used in these experiments the length of the cylindrical 
portion should be more than H in., perhaps equal to the diameter 
of the issuing stream. 

28. Requirements for Temporary Fire Protection for the Interior 
of Buildings. Small fire hose and nozzles should be used as a tem- 
porary protection and brought into play until greater relief is at hand. 
They must necessarily operate under ordinary working pressures in 
the mains more often than under fire pressures. With 40 Ib. per 
sq. in. as an average pressure in the mains, there should be, after 
deducting for losses in the hose and connecting pipes, about 30 Ib. 
per sq. in. at the nozzle. This pressure, of course, would be still 
further reduced if the nozzle used was at a higher elevation than the 
main. With a nozzle pressure of 30 Ib. per sq. in. the K-in. nozzle 
will discharge 40 gal. per min., the Ke-in. and the Y\ e-in. nozzles will 
discharge 30 and 15 gal. per min., respectively. It is felt that the 
discharge from the two smaller nozzles is not great enough for effective 
work. It is true that the pressure at the nozzle for the smaller sizes 
with a given pressure in the main will be somewhat greater than for 
the M-in. nozzle, because of the decreased velocity in the hose which 
will give a smaller loss of head, but this difference in pressure will not 
be enough to increase the discharge materially for an ordinary length 
of hose. The discharge from the iKe-in. nozzle is too small to be very 
effective even at higher pressures. The discharge for a pressure of 
100 Ib. per sq. in. is but 28 gal. per min. It is recommended that 
M-in. nozzles be used with IM-in. hose. For nozzles larger than M 
in., the discharge would become greater and increase the loss of head 
in the hose to such an extent that there would not be enough nozzle 
pressure left to produce a stream which would carry a sufficient distance. 

With the aid of the tables the discharge for any of the nozzles 
may be readily computed for any pressure in the mains. If the nozzle 
is at a higher elevation than the main, subtract from the pressure in 
the main an amount equal to 0.434 times the difference in elevation in 
feet between the nozzle and the main. Take a discharge from the 
table for any pressure at the base of the nozzle for the size of nozzle 
used, then take the corresponding value of the head lost in the kind of 
hose used, multiply this value by the length of hose in feet used and 
divide by 100. The result gives the total loss in the hose for the 
assumed discharge. If there is any connecting pipe, the loss in it will 
be the same as the loss in a corresponding length ^of rubber-lined hose. 



58 ILLINOIS ENGINEERING EXPERIMENT STATION 

Add the losses in the pipe and hose to the pressure at the base of the 
nozzle for the assumed discharge to obtain the pressure in the main 
(corrected for the difference in elevation) necessary to produce this 
discharge. The discharge will vary as the square root of this pres- 
sure. Letting q f = the assumed discharge, P' = the pressure in the main 
(corrected for the difference in elevation) which will produce this dis- 
charge, 5 = the discharge to be determined, P = the actual pressure in 
the mains and H = difference in elevation between the nozzle and the 
main in feet gives the relation 

P^QAZIH 

P' 
which gives the required discharge. 

To illustrate the use of the formula the following assumptions are 
made. Pressure in mains, P = 60 Ib. per sq. in., 80 ft. of linen hose, 
50 ft. of IK-in. connecting pipe, elevation of nozzle above main 30 ft. 
and M-in. nozzle used. 

Assume a discharge of 46 gal. per min. and from the table the 
following values are obtained: 

Nozzle pressure = 40 

. , 80X18.8 

Loss in hose = r^r = 15.0 

50X10.2 
Loss in pipe = r^ = 5.1 



Total = P' = 60l 

Substituting in the formula 

5 = 40.7 gal. per min. 

The following method may be used to determine the discharge 
for any size of nozzle for any pressure in the mains. Assume any 
pressure at the base of the nozzle, h f , in feet of water. The discharge 
for this pressure may be determined by the formula 



q' = discharge in cu. ft. per sec. 

c coefficient of discharge and may be taken as 0.98 
A = area ofjDpening of nozzle in sq. ft. 
20 = 64.4 ft. per sec. per sec. 

Determine the velocity in the_hose for this discharge from the 
formula 



HYDRAULIC EXPERIMENTS 59 



- 



v velocity in hose in ft. per sec. 
a = area of hose in sq. ft. 
Determine the loss in the hose from the formula 



/z 2 = head lost, in feet 
f= friction factor which may be taken as 0.03 for rubber lined 

hose or . 06 for unlined linen hose 
I = length of hose in feet 
d = diameter of hose in feet 
v = velocity in hose in ft. per sec. 
20 = 64.4 ft. per sec. per sec. 

If there is any pipe connecting the hose to the main, the loss for 
it may be computed by the same formula as for the hose, using 0.03 
for the friction factor for IM-in. pipe. Call this lost head h z . 

The pressure in the main to give the assumed nozzle pressure is 



This pressure will be in feet of water. Then using the relation 



-'VI 



gives the required discharge. If the main is below the nozzle, subtract 
the difference in elevation in feet from H in the formula. 

It is recognized that this method is not strictly accurate since the 
head does not vary exactly as the square of the discharge, but the 
results obtained will be close enough for practical use. 



- 



29. Summary. The following brief summary is given as applying 
small hose and nozzles with velocities in the hose ranging from about 
4 to 8 ft. per sec. and with pressures at the base of the nozzle ranging 
from about 10 to 85 Ib. per sq. in. 

(1) The friction factor (/ in the equation for the lost head, 

7 9 \ 

h =f -j^r- I for rubber-lined hose varies but little with the velocity 
d Zcj / 

in the hose and is nearly the same as for clean iron pipe of the same 
diameter. 



60 ILLINOIS ENGINEERING EXPERIMENT STATION 

(2) The friction factor for unlined linen hose decreases as 
the velocity increases. In general the loss of head in unlined linen 
hose is about twice as great as in rubber-lined hose of the same 
diameter and for the same velocity. 

(3) The nozzle should have a smooth cylindrical tip at least 
one-half inch long to keep the jet from spraying. A cylindrical 
tip is a much more important factor in securing a good fire stream 
than a smooth surface in the interior of the nozzle. 

(4) Nozzle openings commonly in use to supply fire streams 
in the interior of buildings seem too small for adequate temporary 
fire protection. It is recommended that a nozzle with a M-in. 
opening be used with a IK-in. hose in order to secure a sufficient 
quantity of water for an effective fire stream. 

(5) The coefficient of discharge of a small conical nozzle 
varies but little with the velocity and is close to 0.98. The value 
of 0.95 obtained with the %6-in. nozzle, which was 12 in. long as 
compared with 6 in. for the other nozzles tested, indicates, how- 
ever, that the nozzle should be short to obtain the value of 0.98. 
A cylindrical tip on the nozzle seems to have little influence on 
the coefficient of discharge. 



PART IV 
THE ORIFICE BUCKET FOR MEASURING WATER 

BY MELVIN L. ENGER 

ASSOCIATE PROFESSOR OF MECHANICS AND HYDRAULICS 



CONTENTS 

PART IV 
THE ORIFICE BUCKET FOR MEASURING WATER 

PAGE 

X. INTRODUCTION 65 

30. Purpose 65 

31. Acknowledgment 66 

XI. APPARATUS AND METHOD OF CALIBRATING 67 

32. Orifice Bucket . . 67 

33. Method of Calibrating Orifice Bucket 71 

XII. EXPERIMENTAL DATA AND DISCUSSION 72 

34. Fifteen-inch Orifice Bucket having Fifty-six Orifices . 72 

35. Fifteen-inch Orifice Bucket having Only Three Orifices 73 

36. Twenty-inch Orifice Bucket having Nineteen Orifices . 73 

37. Conclusions . 76 



LIST OF FIGURES 

NO. PAGE 

23. Fifteen-inch Orifice Bucket having Fifty-six Orifices 67 

24. View Showing Orifice Bucket in Use 69 

25. Twenty-inch Orifice Bucket having Nineteen Orifices 68 

26. Calibration Curves for 15-inch Orifice Bucket having Fifty-six Orifices . 72 

27. Calibration Curves for 15-inch Orifice Bucket having Only Three Orifices 74 

28. Calibration Curves for 20-inch Orifice Bucket having Nineteen Orifices . 75 



64 



HYDRAULIC EXPERIMENTS 65 

PART IV 
THE ORIFICE BUCKET FOR MEASURING WATER 



X. INTRODUCTION 

30. Purpose. The purpose of Part IV is to describe a method 
of measuring water by means of a simple, portable, and inexpensive 
device, here called an orifice bucket, and to present experimental data 
applying thereto for a range of conditions sufficient to indicate that 
the device is reliable for use in engineering practice. An orifice bucket 
is a cylindrical vessel into which water to be measured falls vertically 
and passes out through a number of holes or orifices in the bottom. 
A vertical glass tube placed just outside the bucket is connected to the 
sides of the bucket near the bottom, and the height of the water in 
the tube indicates the head on the orifice. 

The orifice bucket was devised for the purpose of measuring the 
discharge of several artesian wells pumped by means of air lift, the 
water from each of which discharged into a separate cistern or small 
reservoir through a vertical pipe. In each case the water left the pipe 
with considerable blast and momentum. Several possible methods 
for the measurement of the discharge were considered but were thought 
to be impracticable for various reasons or inapplicable for the particular 
case. After some preliminary laboratory experimenting an orifice 
bucket was devised which served very satisfactorily in determining the 
discharge from each of the wells. It was at first feared that the water 
would enter the bucket with such a blast that entrained air would enter 
the vertical glass tube and cause trouble in determining the height of 
water in the bucket. There was, however, no trouble from this cause 
and the fluctuations of the water level in the glass tube offered no seri- 
ous difficulties. 

The orifice bucket has also given satisfaction in tests made to deter- 
mine yields of well pumps of the reciprocating type. It should give 
satisfactory results in the field where simplicity of construction and 
portability are desirable and where extreme accuracy is not of great 
importance. 



66 ILLINOIS ENGINEERING EXPERIMENT STATION 

31. Acknowledgment. The orifice bucket was developed by the 
writer through experimental work in the Hydraulic Laboratory of 
the University of Illinois during 1910 and 1911.* Considerable im- 
provement has been made in the arrangement of certain parts of the 
bucket by I. W. FISK, P. S. BIEGLER, and P. J. NILSEN, of the de- 
partment of electrical engineering, in connection with tests on electric 
motor-driven deep-well pumps. Some of the experimental data herein 
presented were obtained by them, to whom acknowledgment is made. 



* A part of the results here presented was published in the Proceedings of the Third Meeting of 
the Illinois Water Supply Association, p. 87, 1911. 



HYDRAULIC EXPERIMENTS 



67 



XL APPARATUS AND METHOD OP CALIBRATING 

32. Orifice Bucket. Fig. 23 shows the construction and dimen- 
sions of one of the first orifice buckets used in the experiments, and 
Fig. 24 shows the bucket in use. This bucket weighed 23 Ib. 

As previously stated an orifice bucket is a cylindrical vessel having 
holes or orifices in its bottom and into which water to be measured 




nd 
fo 



I 

I 



FIG. 23. FIFTEEN-INCH ORIFICE BUCKET HAVING FIFTY-SIX ORIFICES 



68 



ILLINOIS ENGINEERING EXPERIMENT STATION 



falls vertically, the head of water on the orifices being indicated by 
the height of the water in a vertical glass piezometer tube attached 
near the bottom of the bucket. 

Fig. 25 shows the construction of the most elaborate orifice bucket 
which has been used. It is provided with a short tube checker-work 
to smooth out the flow of the water on its way to the orifices in the 




$'6age g/ass on 
sca/e graduated 
'* *s feef 



ga/v. /'ron s/r/ps 4 



crisscrossed 
to form tubes 
G0/K w/naow screen 
so/denzd to fop- 



ftezomefer press, chamber. 



Bottom of,%"6oi/erp/afe 
r/ise/ed and so/derec/ 



fio/es. 



FIG. 25. TWENTY-INCH ORIFICE BUCKET HAVING NINETEEN ORIFICES 




FIG. 24. VIEW SHOWING ORIFICE BUCKET IN USE 



HYDRAULIC EXPERIMENTS 71 

bottom of the bucket. The vertical glass tube is connected to a 
piezometer chamber or ring around the base of the bucket, pressure 
being transmitted to the piezometer ring through a large number of 
small holes. 

The orifice bucket may be adapted for the measurement of water 
for a considerable range in the discharge by varying the head on the 
orifices and also by varying the number of holes which are stopped or 
plugged with corks or wooden stoppers. The range in the capacities 
of the orifice buckets which have been used is from about 40 to 1000 
gal. per min. 

33. Method of Calibrating Orifice Bucket. In calibrating the ori- 
fice bucket it was hung underneath a vertical pipe as shown in Fig. 24. 
The quantity of water discharged was measured with a 6-in. Venturi 
meter in most of the calibration tests although a calibrated measuring 
pit was used in some of the tests to determine the volume discharged 
in a given time. 

With a given number of holes open, the flow in the orifice bucket 
was regulated by means of a valve between the Venturi meter and the 
bucket until the height in the bucket remained constant. The Venturi 
meter reading and the head on the orifices were then taken. This 
procedure was repeated for several different heads and for different 
numbers of orifices open. 

The effect of varying the conditions of flow was investigated some- 
what. The height of the free fall of the water from the inflow pipe to 
the orifice bucket was varied; likewise different sizes of pipe were used 
giving different velocities to the stream entering the bucket. The 
stream was also allowed to enter near to one side of the bucket instead 
of at the center. Different groupings of the open orifices, furthermore, 
were tried, and different methods were employed in attempting to 
spread or distribute the inflowing stream. 

In using the orifice bucket it is necessary to estimate the average 
head shown in the glass tube because there is some fluctuation. The 
amount of the fluctuation may be reduced by throttling the valve in 
the connection of the glass tube to the orifice bucket. If the proper 
conditions are observed, there should be little trouble from this source. 
It should be remembered that the rate of discharge is proportional to 
the square root of the head and that the effect of the error which might 
occur in the head reading itself is thus reduced in determining the 
discharge. 



72 



ILLINOIS ENGINEERING EXPERIMENT STATION 



XII. EXPERIMENTAL DATA AND DISCUSSION 

34. Fifteen-inch Orifice Bucket Having Fifty-six Orifices. Fig. 26 
shows the calibration curves for the 15-inch orifice bucket shown in 
Fig. 23 and 24. There were fifty-six 1-in. holes in the bottom of the 
bucket giving a maximum capacity of about 1000 gal. per min. With 
all the orifices open the rate of discharge was varied from about 600 
to 1000 gal. per min. by varying the head from about % ft. to 2 ft. 
With thirty-two orifices open the discharge had a range of about 300 
to 600 gal. per min. by varying the head from about Y* ft. to 2.5 ft. 
In closing the twenty-four orifices, corks were used of such size that 
they projected but little into the bucket. It was found that in filling 
the orifices a symmetrical arrangement gave somewhat steadier action, 
particularly when the orifices near the circumference were the ones 
filled. The inflowing stream was discharged from an 8-in. pipe. A 



1000 




0.5 



/-O /.f 2.O 

/iead in feet 



3.0 



FIG. 26. CALIBRATION CURVES FOR 15-iNCH ORIFICE BUCKET HAVING 
FIFTY-SIX ORIFICES 



HYDRAULIC EXPERIMENTS 73 

3-in. pipe was also tried but did not give satisfactory results, on account 
of the high velocity which produced an extremely agitated condition 
of the water in the bucket. This condition may be overcome, however, 
by use of a deflector or distributor, such as an open bag or sack attached 
to the end of the discharge pipe. 

The rate of discharge for any other number of open orifices for this 
bucket may be obtained from the equation 



which represents fairly well the relation between the quantity, q, in 
gal. per min., the number of orifices open, n, and the head in the 
bucket, h, in ft. The experiments give an average coefficient of dis- 
charge for the 1-in. orifices of this bucket of about 0.63. 

35. Fifteen-inch Orifice Bucket Having Only Three Orifices. 
Fig. 27 shows an orifice bucket of the same dimensions as the' one just 
described but with three iron tubes about 1 in. long inserted in a 1-in. 
wooden bottom. It was provided with two screens through which the 
water passed on its way to the orifices hi the bottom of the bucket. 

Fig. 27 also shows the calibration curves for this orifice bucket. 
It will be noted that the discharge ranges from about 35 to 115 gal. 
per min. This orifice was constructed and calibrated for immediate 
use and not for experimental purposes. The calibration curves are of 
value in indicating the reliability of the orifice bucket under a rather 
wide range in the details of its construction. 

36. Twenty-inch Orifice Bucket Having Nineteen Orifices. An 
illustration of the most elaborate orifice bucket used in the experi- 
ments is shown in Fig. 25, the capacity of which is about 1000 gal. 
per min. It contains a checkerwork of vertical tubes through which 
the water flows in passing to the orifices. The gage glass which 
indicates the head on the orifices is connected to a piezometer ring or 
chamber around the base of the bucket. The pressure of the water in 
the bucket is transmitted to the piezometer chamber through a large 
number of M-in. holes. The bottom of the bucket consists of jKe-in. 
boiler plate in which nineteen 1%-in. circular holes are drilled. 

The calibration curves for this orifice bucket are shown in Fig. 28, 
for all holes open and for ten holes open. The discharge for any other 
number of orifices open may be found with a fair degree of accuracy 
from the equation 



IZU 

no 
too 

\ 90 

I 

i" 

r 

x 

r 

60 
SO 
40 
3O 














































/ 










































> 


/ 






i 


<gcree/7 








i 






















/ 


/ 































/ 


s 
















. 












</ 


/ 


/ 
















(2? 

w 








?' 


|f- 


n 




















A) 




. 






1 


1 


fl 












i 


&^ 


IJ 


r 


c^ 














f 










^ 


^ 


ft 


























/ 


/ 








^ 


*\ 




























/ 


^ 








1- 
































/ 










/ 


x 
















/^x 






X 


<* 
















/ 


s 














(* 

r 


$ 


F 


x 


^^ 


















/ 










Ix* 3 

o 


1C 


"6 


aa 

^ 


S 
































c 


IP^ 


4$ 




































<* 


* 




































, ^t 


^ 


/ 







































= 


/ 










































/ 













































tfe&d /n feet 

FIG. 27. CALIBRATION CURVES FOR 15-iNCH ORIFICE BUCKET HAVING 
ONLY THREE ORIFICES 



HYDRAULIC EXPERIMENTS 



75 



if 



Ho/es Plugged thus: 




.6 .8 /.O 



. . . 
Head in feef 



ZO 2 



FIG. 28. CALIBRATION CURVES FOR 20-iNCH ORIFICE BUCKET HAVING 
NINETEEN ORIFICES 



76 ILLINOIS ENGINEERING EXPERIMENT STATION 



in which q is expressed in gal. per min., n is the number of holes open, 
and h is the head on the orifices in feet. The average coefficient of 
discharge for the 1%-in. orifices of this bucket is 0.61. 

The curves in Fig. 28 were obtained when the bucket was supported 
firmly in an upright position with the stream to be measured discharging 
vertically in the center of the bucket and with the free fall into the 
bucket small. The velocity of the inflowing stream, furthermore, was 
not high (2 or 3 ft. per sec.), thereby causing" but little agitation of 
the water in the bucket. Experiments, however, in which more or less 
variation from these conditions were allowed indicated that no serious 
errors resulted. 

37. Conclusions. The conditions under which the discharge of 
water has to be measured are so varied and the purpose or aim in deter- 
mining the discharge differs so much in different problems that nearly 
any one of the many common methods of measuring water has a rather 
restricted field of usefulness, while some methods apply only to very 
special conditions. 

The orifice bucket is designed to meet rather special conditions. 
It is peculiarly adapted for the measurement of water where a device 
which is portable (light weight and small size), simple in construction, 
and low in cost are essential features. The measuring capacity, more- 
over, covers a considerable range. The orifice bucket is particularly 
fitted for the measurement of water when the water discharges with 
considerable blast and momentum from the end of a vertical pipe, in 
such a manner that the spray covers the entire surface of the water in 
the bucket, as in the case of air lift pumping. When so used the orifice 
bucket gives results which should be correct within 5 per cent if the 
proper precautions are observed in its use, as is shown by the calibration 
curves, and correct within 10 per cent for the more unfavorable condi- 
tions to be met in the field. The highest accuracy is obtained when 
the orifice bucket is supported rigidly in an upright position with the 
center of the discharging stream vertically over the center of the bucket. 
The free fall of the water should be as small as possible and the velocity 
of the water as it enters the bucket should not be large, unless the stream 
is distributed, so as to avoid high local velocities in the bucket. The 
orifice bucket, however, gives very satisfactory results even when there 
are considerable deviations from these desirable conditions and renders 
a service for which other measuring devices may not be adapted. 



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*Bulletin No. 92. The Tractive Resistance on Curves of a 28-Ton Electric Car, by E. C. Schmidt 
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^Bulletin No. 93. A Preliminary Study of the Alloys of Chromium, Copper, and Nickel, by 

D. F. McFarland and O. E. Harder. 1916. Thirty cents. 

*Bulletin No. 94. The Embrittling Action of Sodium Hydroxide on Soft Steel, by S. W. Parr. 
1917. Thirty cents. 

^Bulletin No. 95. Magnetic and Other Properties of Iron-Aluminum Alloys Melted in Vacuo, by 
T. D. Yensen and W. A. Gatward. 1917. Twenty-five cents. 

*Bulletin No. 96. The Effect of Mouthpieces on the Flow of Water Through a Submerged Short 
Pipe, by Fred B. Seely. 1917. Twenty-five cents. 

* Bulletin No. 97. Effects of Storage Upon the Properties of Coal, by S. W. Parr. 1917 
Twenty cents. 

^Bulletin No. 98. Tests of Oxyacetylene Welded Joints in Steel Plates, by Herbert F. Moore. 
1917. Ten cents. 

Circular No. 4. The Economical Purchase and Use of Coal for Heating Homes, with Special 
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*Bulletin No. 99. The Collapse of Short Thin Tubes, by A. P. Carman. 1917. Twenty cents. 

*Circular No. 5. The Utilization of Pyrite Occurring in Illinois Bituminous Coal, by E. A. 
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*Bulletin No. 100. Percentage of Extraction of Bituminous Coal with Special Reference to 
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^Bulletin No. 101. Comparative Tests of Six Sizes of Illinois Coal on a Mikado Locomotive, by 

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*Bulletin No. 102. A Study of the Heat Transmission of Building Materials, by A. C. Willard 
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^Bulletin No. 103. An Investigation of Twist Drills, by B. Benedict and W. P. Lukens. 1917. 
Sixty cents. 

*Bulletin No. 104. Tests to Determine the Rigidity of Riveted Joints of Steel Structures, by 
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Circular No. 7. Fuel Economy in the Operation of Hand Fired Power Plants. 1918. Twenty- 
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*BulletinNo. 1 05. Hydraulic Experiments with Valves, Orifices, Hoze, Nozzles, and Orifice 
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-.UNIVERSITY OF CALIFORNIA LIBRARY