240 
Journal of Agricultural Research 
Vol. XXXI, No 3 
Table VII. — Byron-Jackson 4-stage, 17-inch pump, No. 7 
Average 
pump 
speed 
Speed 
of pump 
No. 
of 
run 
Pres¬ 
sure 
head 
Suction 
head 
Static 
head 
Ve¬ 
locity 
head 
Total 
head 
Brake 
horse¬ 
power 
Dis¬ 
charge 
Water 
horse¬ 
power 
Effi¬ 
ciency 
R. p. m. 
R. p. m. 
Ft. 
Ft. 
Ft. 
Ft. 
Ft. 
G.p.m. 
P.ct. 
878 
1 
53.79 
0.00 
12.26 
-0.00 
66.05 
9.09 
0 
0.00 
0.0 
879 
2 
58. 76 
1.13 
12.26 
-.02 
72.13 
9. 70 
109 
1.98 
20.4 
880 
3 
58. 99 
1.58 
12.26 
-.07 
72.76 
12.13 
230 
4.22 
34.8 
Q70 
879 
4 
54.24 
3.16 
12.26 
-.25 
69.41 
14.46 
437 
7.64 
52.8 
Oiu 
880 
5 
48.15 
4.97 
12.26 
-.42 
64.96 
15.00 
561 
9.18 
61.2 
878 
6 
39.97 
7.34 
12.26 
-.66 
58.91 
11.63 
701 
10.42 
89.6 
878 
7 
28. 25 
9.27 
12.26 
-.86 
48.92 
11.46 
804 
9.91 
86.5 
879 
8 
8. 36 
12.43 
12.26 
-1.23 
31.82 
12.91 
964 
7.73 
59.9 
990 
1 
67.12 
.23 
12.26 
-.00 
79. 61 
8.31 
0 
.00 
.0 
995 
2 
76.61 
1.13 
12.26 
-.04 
89.96 
13.22 
164 
3.72 
28.1 
986 
3 
72.09 
3.50 
12.26 
-. 29 
87. 56 
18.97 
464 
10.24 
53.9 
984 
4 
64.41 
5.37 
12.26 
-.46 
81.58 
20.30 
588 
12.09 
59.6 
988 
5 
56.05 
7.57 
12.26 
-. 67 
75.21 
20.05, 
707 
13.42 
66.8 
yoo 
981 
6 
47.23 
8.95 
12.26 
-.84 
67.58 
20.05 
798 
13.64 
67.8 
985 
7 
39.55 
10.40 
12.26 
-1.02 
61.19 
20.05 
873 
13.48 
67.2 
982 
8 
30.06 
11.98 
12.26 
-1.20 
53.10 
19.83 
949 
12.70 
64.0 
985 
9 
19.21 
13.79 
12.26 
-1.46 
43.80 
19.42 
1,045 
11. 55 
59.4 
982 
10 
9.04 
15.14 
12.26 
-1. 59 
34.85 
19.20 
1,094 
9.61 
50.1 
1,086 
1 
82.26 
.00 
12.26 
-.00 
94. 52 
13.29 
0 
.00 
.0 
1,083 
2 
92.89 
.45 
12.26 
-.01 
105.59 
14.35 
93 
2.47 
17.2 
1,075 
3 
93.11 
1.13 
12.26 
-.06 
106.44 
17.95 
211 
5.66 
31.5 
1,068 
4 
90.85 
2.71 
12.26 
-.22 
105.60 
22.19 
404 
10.75 
48.4 
1,073 
1,070 
1,074 
5 
6 
82.04 
74.35 
5.42 
7.57 
12.26 
12.26 
-.47 
-.69 
99.25 
93.49 
25.17 
26.58 
593 
716 
14.85 
16.89 
•58.9 
63.5 
1,071 
7 
63.28 
9.61 
12.26 
-.90 
84.25 
25.78 
825 
17.54 
68.0 
1,069 
8 
50.62 
11.64 
12.26 
-1.14 
73.38 
26.12 
927 
17.16 
65.6 
1,069 
9 
32.32 
14.46 
12.26 
-1.50 
57.54 
24.69 
1,058 
15.34 
62.1 
1,067 
10 
11.75 
18.08 
12.26 
-1.93 
40.16 
23.77 
1,202 
12.18 
51.2 
1,162 
1 
112.44 
.00 
12.26 
-.00 
124.70 
16.46 
0 
.00 
.0 
1,165 
2 
112. 77 
.23 
12.26 
-.00 
125.26 
17.04 
48 
1.52 
8.9 
1,149 
3 
111.42 
1.13 
12.26 
-.05 
124. 76 
20.98 
199 
6.27 
29.9 
1,150 
4 
102.60 
4.92 
12.26 
-.43 
119.35 
29.34 
564 
16.98 
57.8 
1,154 
5 
94.69 
6. 55 
12.26 
-.60 
112.90 
30.89 
671 
19.12 
61.7 
1,155 
1,148 
6 
90.85 
7.57 
12.26 
-.70 
109.98 
31.22 
727 
20.18 
64.5 
1,153 
7 
83.39 
9.04 
12.26 
-.86 
103.83 
31.77 
805 
21.09 
66.3 
1,153 
8 
70.06 
11.75 
12.26 
-1.17 
92.90 
32.89 
939 
22.01 
66.8 
1,155 
9 
44.97 
15.93 
12.26 
-1.71 
71.45 
31.80 
1,126 
20.30 
63.7 
1,155 
10 
33.00 
18.36 
12.26 
-1.98 
61.64 
31.84 
1,219 
18.96 
59.6 
1,161 
11 
21.70 
19.55 
12.26 
-2.24 
51.27 
30.55 
1,280 
16.55 
54.2 
DISCUSSION OF TYPICAL CHARACTERISTIC CURVES 
A typical characteristic diagram, including a capacity-head curve 
an efficiency curve, brake and water horsepower curve, and a speed 
curve, is shown as Figure 9, page 241, representing the various charac¬ 
teristics for pump No. 1 when run at an average speed of 898 revolu¬ 
tions per minute. 
CAPACITY-HEAD CURVE 
The capacity-head curve represents the relation between the total 
heads pumped against and the corresponding quantities of water 
in gallons per minute which the pump is capable of delivering when 
operated (in this instance) at an average speed of 898 revolutions 
per minute. The pump was started with zero discharge, i. e., the 
gate-valve control was closed and an initial total head of 128.6 feet 
was attained (see Table I). As the valve was slowly opened, the 
head gradually increased until a flow of 318 gallons per minute was 
reached with a total measured head of 134 feet. The head then 
dropped gradually, upon further opening of the control valve, until 
it came again to the measured total head of 129.3 feet, but with the 
discharge increased to 468 gallons per minute. 
Thus it is seen that in this portion of the capacity-head curve 
there are two capacities of the pump for heads ranging from 128.6 
