The diaphragm acts as a separation membrane between the compressed air and the liquid. Driving the diaphragm with air instead of the shaft balances the load and removes mechanical stress from the diaphragm, dramatically extending diaphragm life. The compressed air moves the diaphragm away from the center block of the pump. The opposite diaphragm is pulled in by the shaft connected to the pressurized diaphragm. Atmospheric pressure forces fluid into the inlet manifold forcing the inlet ball off its seat.
Liquid is free to move past the inlet valve ball and fill the liquid chamber.
These same hydraulic forces lift the discharge valve ball off its seat, forcing fluid flow to flow through the pump discharge. Atmospheric pressure forces fluid into the inlet manifold of the pump. The inlet valve ball is forced off its seat allowing the fluid being transferred to fill the liquid chamber. As the pump reaches its original starting point, each diaphragm has gone through one air exhaust or one fluid discharge stroke. This constitutes one complete pumping cycle.