18 
BULLETIX 
U. S. DEPARTMEXT OF AGRICULTURE. 
pounds, wheu it is insufficient to deliver the remaining water 20 
feet high. It will also be found that when air is compressed in the 
same tank with water, the water gradually absorbs the air, thus 
making constant renewal of the air necessary. Both of the above 
troubles are overcome by compressing excess air in with the water 
until the pressure gauge again registers 25 pounds, if the tank is half 
full of water. Excess air pressure may be secured by an air intake 
valve in the suction pipe, controlled by hand, by a combination of 
air and water pump, or byuse of an air compressor when power is used. 
in=*s=m 
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Fig. 15. — Pneumatic tank supply system with tank in basement supplied by windmill deep-well 
pumping outfit. 
The following table gives the pressures in the tank necessary to 
force water to certain heights in the house: 
Feet head of water and equivalent pressure in tank. 
Elevation. 
Pressure 
in tank. 
Elevation. 
Pressure 
in tank. 
Elevation. 
Pressure 
in tank. ! 
Feet. 
Pounds. 
Feet. 
Founds. 
Feet. 
Pounds. 
1 
0.43 
20 
8.66 
lO 
32.48 
2 
.87 
25 
10.83 
SO 
34.65 
3 
1.30 
30 
12.99 
85 
36. SI 
4 
1.73 
35 
15.16 
90 
3S.98 

2.17 
40 
17.32 
95 
41.14 
6 
2.60 
45 
19.49 
100 
43.31 
7 
3.03 
50 
21.55 
no 
120 
47.64 
8 
3.40 
OO 
23.82 
51.97 
9 
3.90 
60 
25.99 
130 
56.30 
10 
4.33 
65 
28.15 
140 
60.63 
15 
6.50 
70 
30.32 
150 
64.96 
