How should the speed of stopping the pump and closing the outlet valve be controlled?
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I notice that in the operating procedures for many centrifugal pumps, the procedure for shutting down the pump involves \"slowly closing the outlet valve until it is fully closed, and then pressing the shutdown button.\" Here, however, we require \"quickly closing the outlet valve, and pressing the shutdown button as soon as the pump’s current drops to the no-load level.\" Which of these two methods is correct? Which one is good? Note: Multi-stage centrifugal pump with 400 horsepower, rotational speed of 2980, outlet flow rate of 200 t/h ；
It seems that speed doesn’t make a difference; what might have an impact is the requirement regarding the opening and closing of the outlet valve when the pump is switched.
Personally, I think it should be done slowly, as during the switching process of the pumps, opening or closing them quickly can have an impact on the system. If the operation is too rapid, the two pumps often fail to operate synchronously, resulting in fluctuations in flow and pressure; this has a particularly significant effect on devices with interlocks, which may lead to an automatic shutdown. So it’s better to switch slowly. Of course, for equipment whose operation is not affected by the shutdown of the pump, the speed has little impact on the pump; however, for multi-stage pumps, it’s better to operate them at a faster speed.