Working principle of Air Operated Diaphragm Pumps

Air Operated Diaphragm Pumps are oscillating positive displacement pumps with two pump chambers arranged opposite each other. Both of these are separated by a diaphragm each into an air and a fluid section.

Both diaphragms are linked by a piston rod, so that with every stroke product is displaced to the outside from the one pump chamber and product is drawn into the opposite pump chamber. The four drawings opposite describe the sequence of a complete cycle consisting of a suction and pressure stroke, an empty and a filled pump chamber.

 In order to explain the function the product to be pumped was highlighted in colour.

By filling the right hand air chamber (dark grey) the right hand diaphragm is pressed towards the outside. The piston rod thereby pulls the left hand diaphragm to initial position. Valve ball (1) is pulled out of its position, product (grey) flows into the left hand pump chamber. At the same time valve ball (2) is fixed in end position by the vacuum. The left hand pump chamber is thus completely filled with product (grey).

After switching of the control valve air flows into the left hand air chamber (dark grey), the right hand air chamber is vented. The suction process (see A) now takes place in the right hand pump chamber. Product (dark grey) is drawn in , product (light grey) in the left hand pump chamber is displaced to the outside. Valve ball (1) presses down, closes and valve ball (2) opens the flow path for product to the pressure outlet port.