Diaphragm Pumps:

Diaphragm pumps are also categorized as positive displacement pumps since the diaphragm acts as a limited displacement piston. A pump will function while a diaphragm is forced within reciprocating motion through mechanical linkage, compressed air or fluid from a pulsating, external source. A pump construction eliminates some contact among the liquid being pumped and the source of energy. That eliminates the possibility of leakage that is important while handling toxic or extremely expensive liquids. Drawback involves limited head and capacity range, and the requirement of check valves in the suction and discharge nozzles. An instance of a diaphragm pump is displays in Figure.

Figure: Diaphragm Pump