Why can self-priming pump self-priming

Before the self-priming centrifugal pump is turned on for the first time, only 2/3 of the water needs to be poured into the self-priming pump shell, and then the water can be automatically sucked up after starting the self-priming pump. Self-priming centrifugal pump is very easy to start, and it is also very convenient to use, and it is widely used in farmland sprinkler irrigation and water conservancy projects.

The reasons for the self-priming pump and the principle of 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 it generally has a double pump housing. In this way, before starting, there is always a part of water in the shell of the self-priming pump. When the impeller of the self-priming pump rotates, the stored water is thrown to the outer edge of the impeller under the action of centrifugal force, and a vacuum is formed at the entrance of the impeller. The air in the inlet pipe is sucked into the impeller from the pump inlet, forming a gas-water mixture at the outer edge of the impeller, rising along the volute flow path. Due to the increase in section, the flow rate of gas-water mixture decreases, the air overflows from the outlet of the separation chamber, and the water returns along the lower part of the volute flow channel under the action of its own weight, and enters the pump shell flow channel and the air in the pump is mixed again, so repeated many times, the air in the suction pipe is gradually excluded, and the inlet pipe forms a negative pressure state after the air is drained, and the water will be slowly inhaled into the pump body. After the pump body due to the role of the self-priming pump to speed up the flow rate of water, so that the water in the inlet pipe speed up, to achieve the self-priming effect of the self-priming pump. The main components of the self-priming pump are basically the same as that of the single-stage single-suction centrifugal pump.