A diaphragm pump (also called a Membrane pump) is a positive displacement pump that runs on the combination of the reciprocating action of a rubber, thermoplastic or teflon diaphragm and suitable valves on either aspect of the diaphragm
A dual diaphragm is a positive displacement pump which utilises two flexible Air Diaphragm Pump diaphragms that reciprocate back and forth, creating a temporary chamber, which both draws in and expels fluid through the pump. … The two 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 application, a positive displacement pump, is normally a self-priming pump. … For example, air operated diaphragm pumps self-prime by creating a pressure differential in the diaphragm chamber. This draws in air and pulls the liquid in to the suction port.