Solving the pump selection problem under a limit vacuum condition
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Gentle experts, this is my first time on this forum; I’ve been struggling for a long time with pump selection under a certain operating condition. I urgently seek the help of experts! At -0.1 MPa, the liquid in the collection tank is circulated within the system. The collection tank is 1 meter high; the pump and the tank are at the same height, with no liquid level difference between them. The properties of this material are similar to those of water. The pump fails to deliver fluid due to excessive negative pressure. When a centrifugal pump is used, it fails to deliver the required flow rate; severe cavitation in a self-priming pump causes the impeller nuts and the impeller itself to loosen, resulting in increased noise and reduced performance. I’m asking the experts: is there any pump that can operate in a cyclic manner under such conditions?
Try using a positive displacement pump; this type of pump has a certain degree of self-priming capability
When using a positive displacement pump, it is essential to provide accurate specifications for its selection; otherwise, the pump delivered cannot be operated.
There should be no problem using a centrifugal pump; turn on the pressure equalization line before starting the pump!
Positive displacement pumps are the preferred choice, such as gear pumps. There is no principle-related issue with this centrifugal pump; it’s merely a sealing problem that allows air to enter the pump, resulting in cavitation.
Since cavitation prevents the centrifugal pump from delivering sufficient flow, first calculate the effective net positive suction head. Then select a pump whose required net positive suction head is at least 0.3 m lower than the effective value. If no such pump is available, consider raising the position of the tank or lowering the position of the pump
It was mentioned earlier that for positive displacement pumps, if the net positive suction head is not sufficient, then such pumps are also not suitable
I tried it before; turning on the equalization line didn’t work either. Now, using a self-priming pump, there is cavitation, but it can barely be used
I tried a gear pump; the fluid has no viscosity, and the gears got stuck
Hello, teacher. What is a equalization wire?