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Working principle of diesel engine self-priming pump

Article provenance:Hai Rui ZhonglianPopularity:Publication time:2020-03-25 10:40

Working principle of diesel engine self-priming pump

The self-priming pump of diesel engine is a kind of self-priming centrifugal pump with compact structure, convenient operation, stable operation, convenient maintenance, high efficiency, long service life and strong self-priming force. The pipeline does not need to install the bottom valve, just to ensure that the pump body has a fixed amount of liquid intake before work. Different liquid can use different material of self - priming pump

The working principle of self-priming pump is that the pump shell is full of water (or there is water in the pump shell) before the pump starts. After the start, the impeller rotates at high speed so that the water in the impeller passage flows to the volute. At this time, a vacuum is formed at the inlet to stop the inlet valve, and the air in the suction pipe enters the pump and reaches the outer edge through the impeller channel.

Self priming pump structure

There are many types of self-priming pumps, including molten salt pump, vacuum pump, submersible pump, diesel self-priming pump, gear pump, diesel engine water pump and diesel engine fire pump. Then it joins with the water from the right return hole and flows along the volute. As the liquid continuously impacts the cascade in the volute, it is broken by the impeller and mixed with the air violently to form the air-water mixture. Because of the continuous flow, the air-water mixture cannot be separated. The mixture is peeled off from the tongue at the outlet of the volute and enters the separation chamber along the short pipe. The air in the separation chamber is separated and discharged by the outlet pipe, and the water still flows to the outer edge of the impeller through the left and right return holes and mixes with the air in the suction pipe. Such repeated circulation, gradually exhaust the air in the suction pipe, so that water into the pump, complete the self-priming process. Self priming pump diaphragm pump screw pump gear oil pump is the same, the difference is that the return water does not flow to the outer edge of the impeller, but to the inlet of the impeller. When starting the internal mixing self-priming pump, the return valves at the front and bottom of the impeller must be opened to make the liquid in the pump flow back to the impeller inlet. Under the action of high-speed rotating impeller, water is mixed with air from suction pipe to form air-water mixture, which is discharged into separation chamber. At this time, the air is discharged and the water returns to the impeller inlet from the return valve. This is repeated until the air is exhausted, the water is absorbed, the type of mixing self-priming pump, the working principle and the external mixing self-priming.

The self-priming height of the suction pump is related to the sealing clearance in front of the impeller, the number of rotation of the pump and the height of the liquid level in the separation chamber. The smaller the sealing clearance in front of the impeller is, the larger the self-priming height is, generally 0.3-0.5mm; except for the self-priming height, the lift and efficiency of the diesel engine pump will decrease when the clearance increases. The self-priming height of the pump increases with the increase of the circular speed U2 of the impeller, but at the maximum self-priming height, the number of rotations increases and the self-priming height no longer increases. At this time, the self-priming time will only be shortened. When the number of revolutions decreases, the self-priming height will be reduced. In other conditions, the self absorption height increases with the increase of water storage height (but it can not exceed the optimal water storage height of the separation chamber). In order to better mix gas and water in the self-priming pump, the blades of the impeller must be less, increasing the spacing of the cascades; it is recommended to use a half open impeller (or impeller with a wider impeller channel), so that it is easier to return water deeply to the impeller "cascade".

Most of the self-priming pumps are equipped with internal combustion engines, which are installed on mobile vehicles and are suitable for field operation.