A self-priming pump, also called a centrifugal pump, is one that uses centrifugal force in order to create some form of differential pressure in to pump and displace water from one point to another. Commonly, centrifugal pumps are not able to work as efficient when air is mixed in the water. Self-priming pumps solves this problem by mixing air with the water to create a mixture that has the same pumping properties as with regular water without any air binding the pump. This way, the self-priming pump is able to remove any air that might have entered the pump while displacing the water from the source to another point.
