A self priming pump is a single stage, single suction centrifugal pump that produces self priming effect due to the special structure of the pump itself, and is called a self priming centrifugal pump. Compared with ordinary centrifugal pumps, there are significant differences in pump body structure: firstly, the pump inlet position is increased, and sometimes a suction valve is installed; The second is to set up a gas-water separation chamber on the outlet side.

External self priming pump refers to a self priming device attached to the pump, such as a vortex pump, water ring vacuum pump, jet pump, and manual pump.

Compared with ordinary centrifugal pumps, self priming pumps have a compact structure and simple operation. They not only save the trouble of filling a large amount of water before starting, but also save the low valve of the inlet pipe, reduce the inlet resistance, and increase the pump's water output. However, compared with ordinary centrifugal pumps of the same specification, the efficiency is 3% to 5% lower. Self priming pumps are mostly used in small and light sprinkler irrigation units and pipeline irrigation units.