Regardless of the liquid being transported, must the centrifugal pump be filled with liquid and have its outlet valve fully closed when started?
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Regardless of the liquid being transported, must the centrifugal pump be filled with liquid and have its outlet valve fully closed when started?
The centrifugal pump must be filled with liquid when started, but the outlet valve does not necessarily need to be fully closed.
Keeping the pump outlet slightly open is a requirement before starting a magnetic pump. In devices powered by electricity, it is common for some small pumps to be started without closing their outlet valves first.
To be precise, centrifugal pumps are generally used as low-level pumps, and a suction check valve is also installed. It is not allowed to fully open the outlet valve when starting the pump, in order to prevent excessive load from damaging the motor. When stopping the pump, the outlet valve must be closed first to avoid backflow of liquid that could damage the impellers. However, for plunger pumps and gear pumps, it is necessary to open the outlet valve first to prevent pressure buildup