Diaphragm pumps are a series of pumps that fall under the positive displacement family of pumps. Air-operated double diaphragm pumps (AODDs) have a simple design in which two diaphragms are attached to a common connecting rod. The pump is driven by compressed air through an air distribution system which reciprocates the diaphragms. As one pumping chamber is displaced, the other chamber loads. The process then repeats as the pump changes direction. Inlet and outlet checks either seat or unseat in the process.