944 ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
A tank like this, 12 inches in diameter 
and four feet high, will hold 24 gallons 
and cost about $16. An open galvanized 
steel tank can be made or can be bought 
ready made. A ready made one with a 
capacity of 100 gallons will cost about $8, 
while a 500-gallon tank will cost about 
$16. 
Pneumatic Tanks 
Sufficient pressure to force a water sup- 
ply wherever desired in a farmhouse may 
be secured at all seasons by means of a 
pneumatic tank built of steel plates and 
located in the cellar, or in a small build- 
ing erected over the well, or even buried 
in the earth if desired. It is superior to 
an elevated tank because the pipes and 
tank can more easily be made frost proof 
in winter and the water will be cooler in 
summer. It is closed to dust and light 
and has the additional advantage of rest- 
ing upon the solid ground. 
Principle of Action 
Water is pumped into the bottom of this 
air-tight tank, and as the water rises in 
the tank the air above it is compressed. 
The expansion of this compressed air 
will force the water through the supply 
pipes at the bottom of the tank to points 
where the water is required. The pres- 
sure is increased by pumping more water 
into the tank and decreased by drawing 
water off. A 15-pound pressure will raise 
water to a height of 33 feet, a 10-pound 
pressure to a height of 22 feet, ete. The 
correct amount of air can be supplied and 
maintained by an automatic air valve, by 
a pump that forces both air and water 
into the tank at the same time, or by a 
hand air-valve. The last method is not 
self-regulating, but if water is supplied 
to the tank by a hand force pump, it will 
not require much more attention to regu- 
late the air pressure also. 
Power; Cost 
The water can be forced into the pneu- 
matic tank by the same means required 
to elevate it to a gravity tank, i. e., by a 
windmill, gas engine, hot-air engine, hy- 
draulic ram, or by hand. From ten to 
Pneumatic Pressure Tank Showing Pump and Separator Operated 
by an Electric Motor. 
—Courtesy Kewanee System. 
