The 1st diaphragm generates a stress stroke that removes fluid in the pump. At the same time, the second diaphragm performs the suction stroke.As being the 1st pressurized diaphragm reaches the top of its stroke, air transfers in the 1st diaphragm for the again of the 2nd diaphragm in the air valve. The pressurized air pushes the 2nd diaphragm clea