An air driven diaphragm pump includes two diaphragms affixed to a common shaft. The shaft extends through an air valve providing reciprocating pressurized air to the diaphragms through associated air chambers. A pump chamber with intake and exhaust valves is associated with one of the two diaphragms while a further air chamber replaces a pump chamber and is associated with the other of the diaphragms. A passage extends through the shaft and is in communication with the air chamber adjacent to the pump chamber and with the further air chamber converted from the pump chamber.