42 
BULLETIN 1067, IT. S. DEPARTMENT OF AGRICULTURE. 
motors. Electric energy was used in this case because of the 
desirability of having the city current for use for other power and 
in the suburban residences. The cost of electrical energy is greater 
than that of steam power or that furnished by internal-combustion 
engines, although the first cost of the electrical plant is less than 
either of the other types. The plant is very economical when 
interest on investment and depreciation are considered together with 
the cost of operating. 
The pumps are equipped with a combination of screw and inclosed- 
centrifugal impeller. They are primed by means of small exhaust 
pumps of the chamber-wheel type driven by small motors. Greatest 
capacity is had at the low lifts, where it is desirable. As the lift 
increases the capacity decreases, but the need of large capacity also 
decreases. The capacity of the plant when operating at a lift of 4.5 
feet is 1.3 inches in depth removed from the area in 24 hours. The 
motors which drive the pumps run at practically constant speed, and 
therefore the revolutions of the pump remain constant regardless of 
lift. 
METHOD OF MAKING TEST. 
The height through which the water was elevated was obtained by 
reading gages in the suction and discharge basins. The quantity of 
water was determined by using a Price current meter in the discharge 
flume. The voltage and revolutions per minute were also observed. 
The results of the test are given in Table 36. It is believed that the 
two units under favorable conditions will show identical results. 
Table 36. — Test of pumping plant in Little Woods Tract, New Orleans, La., Nov. 14, 
1914. 
UNIT NO. 1. 
Time. 
Speed. 
Volts. 
Actual 
lift. 
Discharge. 
• 
Kilo- 
watts. 
Elec- 
trical 
horse- 
power. 
Water 
horse- 
power. 
Effi- 
ciency. 
10.00 
10.15 
10.30....... 
10.45 
11.00 
11.15 
3.15 
3.30 
3.45 
4.00 
4.15 
4.30 
R. p. m. 
119.8 
121.2 
120.7 
120.7 
121.2 
121.4 
120.8 
120.5 
120.7 
121.1 
121.0 
120.7 
2,246 
2,288 
2,300 
2,298 
2,298 
2,304 
2,320 
2,320 
2,320 
2,320 
2,316 
2,320 
Feet. 
5.76 
5.83 
5.85 
5.85 
5.87 
5.91 
6.29 
6.39 
6.41 
6.44 
6.46 
6.54 
Sec.-ft. 
173.7 
176.8 
177.9 
175.5 
173.7 
172.1 
171.0 
169.2 
170.2 
168.1 
166.3 
167.4 
G. p. m. 
77,800 
79, 200 
79.700 
78, 600 
77, 800 
77,100 
76,600 
75,800 
76, 200 
75,300 
74,500 
75,000 
174.0 
174.9 
174.8 
175.1 
175.0 
178.0 
174.4 
172.6 
171.6 
173.4 
171.0 
166.4 
233.0 
234.2 
234.2 
234.6 
234.5 
238.5 
233.7 
231.3 
230.0 
232.3 
229.1 
223.0 
113.5 
116.8 
118.0 
116.2 
115.5 
115.3 
121.8 
122.7 
123.5 
122.6 
121.6 
124.1 
Per cent. 
48.80 
49.75 
50.35 
49.50 
49.25 
48.35 
52.10 
53.10 
53.70 
52.75 
53.10 
55.70 
Mean . . 
120.8 
2,304 
6.13 
171.4 
76, 960 
173.4 
232.4 
117.6 
51.37 
UNIT NO. 2.1 
1.15 
1.30 
1.45 
2.00 
2.15 
121.4 
121.1 
12). 8 
121.0 
120.8 
120.8 
2,300 
2, 3 )8 
2,310 
2,310 
2,323 
2,310 
6.10 
6.14 
6.15 
6.2) 
6.25 
6.15 
170.2 
171.5 
171.2 
167.0 
169.2 
169. 8 
7 i, 2J0 
73,800 
76,700 
74, 800 
75,800 
176.5 
178.0 
176.1 
174.0 
173.0 
231.5 
238.5 
236.0 
233.0 
231.8 
117.5 
119.3 
119.2 
117.3 
120.0 
49.7 
50.0 
50.5 
50.4 
50.47 
Mean.. 
'76, 060 
175.5 
235. 2 
118.7 
50.47 
1 A mud lump was found in suction basin under one suction pipe. 
