The pump is driven by an AC or DC motor

In front of the motor is a valve assembly containing two to five valve pump chambers. Each valve chamber has a diaphragmbehind it in the lower pump housing. As the motor shaft turns, an internal cam positioned behind the diaphragms causes the diaphragms to be pushed forward, then back in a continuous sequence creating a suction. As this suction builds, fluid is pulled through the inlet, through the various valve chamber check valves to the outlet

The volume of flow is determined by several factors including: the number and size of the pump chambers, cam offset, operating pressure, fluid viscosity