Self priming centrifugal pump

Enough liquid for priming can be stored in a specially designed pump casing, resulting in a centrifugal pump that is self-priming. During priming the liquid is recirculated within the casing. Gas from the suction port mixes with the liquid in the pump. The impeller repeatedly ejects the mixture back into the casing. The liquid sinks to the bottom of the casing, where it reenters the pump along with more gas from the suction port. Gradually the gas is expelled from the pump into the discharge line, and the suction line fills with liquid. Normal centrifugal pump operation begins.it is mostly used in centrifugal pump in which motor is not applicable to start the priming provides the pump to start because the rotor some time not pumps the fluid the priming act as storage tank in which the fluid is pumped to the centrifugal pump then it is started again to pump the fluid.