Will adjusting the inlet valve of a centrifugal pump cause cavitation?
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The inlet of the company’s centrifugal pump is connected to a 15 m3 water tank, which is about 50 cm above the pump inlet. The inlet pipe is 200, and the pump inlet flange is 100. With the pump inlet and outlet valves fully open, measuring the motor current will cause an overload. Currently, the inlet valve of the regulating pump is set at around 30%, while the outlet valve is fully open. I’m not sure if doing this will cause damage to the pump
There’s no way to do it that way; all inlets are kept open, and the amount is adjusted using the outlets
Why throttle at the inlet? Drive a bit slower when going out
The method of adjusting a centrifugal pump is to adjust only the outlet valve; the inlet valve cannot be adjusted.
The inlet valve is open at 30%, and the outlet is fully open? ? I’ve heard for the first time that, in general, with centrifugal pumps, the pump is started after the inlet valve is fully opened; once it’s operating normally, the outlet valve is gradually opened according to the flow requirements
Since overcurrent is already occurring, it means the power of the pump motor is too low; replace the motor. Even if you adjust the outlet valve to close it more and reduce the flow rate, the head increases accordingly, while the rated power of the pump remains essentially unchanged.
Closing the inlet valve is equivalent to conducting a critical cavitation experiment; if it is not closed to the extent that cavitation occurs in the pump, the flow rate will remain essentially unchanged. If there are too many shut-offs, the pump may experience cavitation, and that would be disastrous
The pump will experience cavitation; in other words, it will make a gurgling sound. Over time, the pump’s impeller and bearings will get damaged. The power of this pump must be quite high; if it runs for a long time, consider replacing it. The flow rate is too low, or the head rating is set too high
Isn’t it all about using outlet throttling?
Using a mechanical type of minimum flow valve can prevent pump cavitation
Keep the inlet fully open and adjust the outlet valve.