Single-stage centrifugal pump is composed of: impeller, pump body, pump cover, pump shaft, bearing body, bearing, seal and so on. The working principle is: impeller driven by the shaft at high speed rotation, the liquid between the leaves must also be rotated. Under the action of centrifugal force, liquid is thrown from the center of the impeller to the outer edge and gains energy, leaving the outer edge of the impeller to enter the scroll casing at a high speed. In the volute, the liquid due to the gradual expansion of the slowing down, but also part of the kinetic energy into static pressure, and finally to a higher pressure into the discharge pipe, to the required place. When the liquid flows from the center of the impeller to the outer edge, a certain vacuum is formed in the center of the impeller. Since the pressure above the liquid level in the sump is greater than the pressure at the inlet of the pump, the liquid is continuously pressed into the impeller. As long as the impeller is constantly rotating, the liquid will be continuously aspirated and discharged.