Before starting the pump, the suction pipe and pump must be filled with liquid. After the pump is turned on, the impeller rotates at a high speed, and the liquid in it rotates with the blades. Under the action of centrifugal force, it flies away from the impeller and shoots outward. The speed of the injected liquid in the diffusion chamber of the pump casing gradually slows down and the pressure gradually increases. Outlet, the discharge pipe flows out. At this time, at the center of the blade, the liquid is thrown around to form a vacuum low pressure zone with neither air nor liquid. The liquid in the liquid pool flows into the pump through the suction pipe under the action of the atmospheric pressure on the pool surface, and the liquid is continuous in this way. It is continuously sucked up from the liquid pool and continuously flows out of the discharge pipe.