Self-priming pumps have a certain degree of self-priming capability, allowing them to start easily and maintain normal operation while still priming water. Most self-priming pumps currently manufactured are centrifugal pumps. Depending on how they self-prime, self-priming pumps can be categorized into various types, including externally mixed self-priming pumps, internally mixed self-priming pumps, and self-priming pumps with a vacuum pump providing the power themselves.

Their key components include the pump body, pump cover, impeller, shaft, and bearings. The pump body features a vortex-shaped flow passage, with a large air-water separation chamber around the surface. A seat angle is cast on the bottom of the pump body to stabilize the pump. The pump's suction inlet is located above the impeller. After each shutdown, some water remains in the pump for the next startup. Before starting the pump again, manually fill the pump with self-priming tap water, ensuring that the impeller is mostly submerged.

When the pump is started, water in the impeller is drawn toward the impeller edge by centrifugal force, where it mixes with the gas, forming a foamy ribbon of water-gas mixture. This foam ribbon, scraped by the baffle, forces the water-gas mixture through the dispersion pipe and into the water-gas separation chamber. At this point, the water flow rate decreases rapidly due to the sudden increase in the water-watering area. The gas, with its lower density, escapes from the water and is discharged through the pump outlet. The water, with its higher density, falls to the bottom of the water-gas separation chamber and returns to the impeller edge through the axial return hole, where it remixes with the gas.

As this process continues, the vacuum in the suction pipe continuously increases, and the transported water continues to rise along the suction pipe. Once the pump is completely filled with water, it enters normal operation and begins self-priming. The pump's inlet and outlet can be connected with hoses or flanges. When using a hose, the inlet hose connector is equipped with a check valve to prevent reverse flow of liquid during shutdown. The vortex flow passage of the pump body is equipped with a closed single-suction impeller, the pump cover is provided with a sealing chamber, the bearing body is equipped with unsalted butter to clean the bearing, the rear end of the pump shaft is equipped with a V-belt pulley or coupling, and the pump is driven by an electric motor or gas turbine.