Why self-priming pump can self-prime and self-priming principle

Before the first self-priming centrifugal pump is used, it only needs to fill 2/3 of the water into the pump casing of the self-priming pump, and then automatically start the water after the self-priming pump is started. Self-priming centrifugal pump is very easy to start, and it is also very convenient to use. It is widely used in farmland irrigation and water conservancy projects.

The reason why the self-priming pump can self-prime and the self-priming principle of the self-priming pump are as follows:

Mainly because the structure of the pump body part of the self-priming pump is different from that of the ordinary centrifugal pump, the main difference is that the suction port of the self-priming pump is higher than the pump shaft; there is no large gas-water separation chamber before the water outlet of the pump and generally has Double pump casing. Thus, before starting, a part of the water is always present in the pump casing of the self-priming pump. When the impeller of the self-priming pump rotates, the stored water is sucked to the outer edge of the impeller by the centrifugal force, and a vacuum is formed at the inlet of the impeller. The air in the pump is sucked from the pump inlet, and a gas-water mixture is formed on the outer edge of the impeller, which rises along the volute flow channel. When the gas-water mixture flows to the gas-water separation chamber, the gas-water mixture increases due to the increased cross-section. The flow rate is reduced, the air overflows from the outlet of the separation chamber, the water flows back along the lower part of the volute flow channel under the action of self-weight, and enters the pump casing flow passage and the air in the pump to be mixed again. This is repeated several times, and the air in the suction pipe is gradually Excluded, after the air is drained, the inlet pipe forms a negative pressure state, and the water is slowly sucked into the pump body. After the pump body, the flow rate of the water is accelerated by the action of the self-priming pump, thereby making the inlet pipe The water flow rate inside is accelerated, achieving the self-priming effect of the self-priming pump. The main components of the self-priming pump are basically the same as the single-stage single-suction centrifugal pump.