There are many structural types of self priming pumps. The principle of external mixing self priming pump is that before the pump starts, water is filled in the pump casing (or the pump itself contains water). After starting, the impeller rotates at high speed, so that the flow in the impeller channel is directed towards the vortex shell. When the inlet is formed, a vacuum is formed, so that the intake check door is opened, and the air in the suction pipe enters the pump and reaches the outer edge through the impeller channel. On the other hand, the water in the air water separation chamber by the impeller goes back to the outer edge of the impeller through the left and right backwater holes. The water flowing back from the left return hole is directed towards the impeller channel under the action of pressure difference and gravity, and is broken by the impeller. After mixing with the air coming from the suction pipeline, it flows to the volute and flows to the direction of rotation. And then right to water in the backwater hole converging flow along the spiral flow. As the liquid is continuously impacting the cascades in the volute, it is constantly crushed by the impeller, and it is strongly stirred with the air to form a mixture of air and water and flow continuously, resulting in the separation of gas and water. The mixture is stripped by the septum at the outlet of the volute and enters the separation chamber along the short tube. In the separation room, the air is separated from the outlet pipe, and the water is still flowing through the left and right backwater holes to the outer edge of the impeller and mixed with the air of the suction pipe. In this way, the air in the suction pipe is drained out gradually, and the water is entered into the pump and the self - suction process is completed.
The internal mixing self-priming pump is the same as the external mixing self - priming pump, the difference is that the return water does not flow to the outer edge of the impeller and flows to the inlet of the impeller. When the internal mixing pump is started, it is necessary to open the reflux valve below the impeller and make the liquid flow back to the inlet of the impeller. The water is mixed with the air from the suction tube under the effect of high speed rotation of the impeller to form a gas water mixture to be discharged into the separation chamber. Here the air is discharged and the water returns from the reflow valve back to the inlet of the impeller. So repeatedly, until the air exhausting, suck up the water.
The self - suction height of the self - suction pump is related to the clearance of the impeller front seal, the number of pump and the height of the liquid level in the separation chamber. The smaller the sealing gap in front of the impeller is, the larger the self suction height is. Generally, it is 0.3~0.5 mm. When the clearance increases, the lift and efficiency of the pump will decrease as well as the self suction height decreases. The self suction height of the pump increases with the increase of the circumferential speed of impeller U2, but when the maximum self suction height is increased, the rotation rate increases and the self suction height does not increase. This time only reduces the self suction time. When the number of revolution decreases, the self suction height decreases. When other conditions are constant, the height of self-priming increases with the increase of the water storage height (but it can not exceed the optimum storage height of the separation chamber). In order to better mix the air and water in the self sucking pump, the impeller blades should be less and the pitch of the cascade should be increased. A semi open impeller (or impeller with wider impeller grooves) should be adopted, which is more convenient for backwater to shoot into the impeller cascade.
Most of the self-priming pump is equipped with the internal combustion engine. It is installed on the removable car and is suitable for the field operation.
- Close This Page
- Recommendation：
- Browse：
