Pressurized Water Storage Tank

the purpose of this standard to prescribe mini-
mum performance and construction requirements
for pressurized storage tanks for service in water
well systems with a maximum factory pre-charge
pressure of 40 psig (280 kPa), to be operated in
ambient air temperatures up to 120°F (49°C), with
maximum working pressures not less than 75 psig
(520 kPa) and not greater than 150 psig (1000 kPa)
and tank volumes not exceeding 120 gallons (450 L).

Most private water systems are powered by an electric
motor and incorporate a closed pressure tank. The
three essential components of such a system are
pump, tank and control. The functions of a water
pressure storage tank are threefold: (1) to protect and
prolong the life of the pump by preventing rapid
cycling of the pump motor (most motor manufactur-
ers recommend pump cycle rates of under 300 for
each 24-hour period and not more than 15 starts per
hour for up to 3/4 hp, and not more than 7-1/2 starts
per hour for greater than 3/4 hp motors); (2) to pro-
vide water under pressure for delivery between cycles;
and (3) to provide additional water storage under
pressure to assist the pump in meeting the total
demands of a system if the pump or well is incapable
of supplying the required capacity.