A diaphragm pump (also referred to as a Membrane pump) is a positive displacement pump that uses a mixture of the reciprocating action of a rubber, thermoplastic or teflon diaphragm and suitable valves on either side of the diaphragm

A dual diaphragm is a positive displacement pump which utilises two flexible diaphragms that reciprocate backwards and forwards, creating a temporary chamber, which both allures and expels liquid through the pump. … Both diaphragms that are connected by a shaft through the centre section where in fact the air valve is located.

Though this will depend upon the pump and Air Diaphragm Pump application, a positive displacement pump, is generally a self-priming pump. … For example, air operated diaphragm pumps self-primary by creating a pressure differential in the diaphragm chamber. This allures surroundings and pulls the liquid in to the suction port.