Has a propeller-type of impeller running in a casing. The pressure is developed by the flow of liquid over the blades of impeller.
Self Priming Pumps are a type of centrifugal pump that can be located above the suction reservoir without an external priming system. End suction configuration, but has an enlarged case to hold some liquid to support priming. When the liquid to pump is below the level of the pump, it has to have a check valve in the suction, and has to be primed, this is to have that suction pipe filled with water, otherwise it will not pump if air gets to get in that suction.
Self Priming Pumps need no check valve, and can start turning no matter if it has air or not, because the discharge of water goes to a chamber that has some water that is pulled even when the pump is empty, it moves in a closed circuit, making suction to lift the water from the lower level, once the pump eliminates the air from the suction pipe, it pumps water up.
