Self-priming pump working principle is: water pump filled with water in the pump casing before you start (or pump housing itself being water). Starts the flow in the impeller of high-speed rotating impeller channels to the volute, entrance created a vacuum, cause the inlet check valve, non-return valve to open, suction pipe air into the pump and impeller channels reach the rim. Self-priming pump is self-priming centrifugal pump, it has a compact structure, easy operation, smooth running, easy maintenance, high efficiency, long life, strong self-priming capacity and so on. Lines do not need to install the bottom valve, before the work just make sure pump body are quantitative liquid. Different liquids self-priming pumps of different materials can be used.