What is the difference between a piston style pump and a Diaphragm test pump?
All of Cherne’s hydrostatic test pumps are designed to pressure test new potable water lines. Piston style pumps can be pressure fed or suction fed.
Piston pumps cannot be run dry nor should they be used in conjunction with chlorine. (Chlorine is frequently used when new potable water lines are being tested to avoid contamination).
Diaphragm test pumps cannot be pressure fed. However they can be used with an optional gravity feed water tank sold by Cherne, or with a large container (like a garbage can) filled with water into which the intake hose can be placed.
Diaphragm pumps can be used with up to a 10% chlorine solution in the test water.