SINGLE DIAPHRAGM PRESSURE TANK - PTB 305

Diaphragm tanks are commonly used on the
 discharge manifold to provide water storage 
for the system in very low flow situations. 
It decreases the running time of the booster pumps,
 thereby making the system more energy effective.
A well pressure tank can last from five to 15 years, 
as long as yours is well maintained.

If this happens, there is little air left in
 the tank to become compressed,
 so the pump runs nearly every time water is used.
 In addition, too much air in the tank is a problem
 because it reduces the space for water storage. 

Extra air must be released or the tank will become air-bound.
As stated before, there are three types of tanks: 
Air-Over-Water, Diaphragm, and Bladder.
Typically a double diaphragm pump will be
 able to run continuously at between 40 and
 60 cycles per minute and intermittently