Self Priming
Pumps

A self-priming pump uses a water/air mixture in order to fully prime the pump. While called self-priming pump it is actually a centrifugal pump in principle. It uses a centrifugal force to create a pumping action by using a pressure differential in a liquid and a suction in the priming chamber. The impeller draws the fluid into the pump and displaces it out of the discharge port. The movement of this fluid creates a suction, lifting the water from the sump below into the pump, starting the pumping action. 

When the pump stops, a non return valve within the pump maintains water in the priming chamber, keeping it primed and ready for operation again. Liquid must always be present in the priming chamber to allow the pump to work automatically. On initial start up or after maintenance this priming chamber has to be filled with the liquid to start the process. Self priming pumps generally are suited to transfer high flow applications. The most common use includes water, sewage, petroleum and petrochemical applications.