Starting procedure for centrifugal pumps
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The normal procedure for starting a centrifugal pump is to first open the inlet valve, start the motor, and then open the outlet valve. However, our unit has been experiencing pressure buildup problems frequently lately; therefore, we asked other units if they have encountered such issues as well
Reply to 1# yang*yong0626: It seems that it also depends on the type of pump being used. In the case of pumps used for liquefied natural gas, the outlet valve cannot be completely closed when starting the pump, as this can easily lead to cavitation. Pumps used for water handling do not have this issue; the outlet valve can be closed at the time of starting the pump, and once the pumping is stable (without keeping the outlet valve closed indefinitely), the valve can be slowly opened while monitoring any pressure fluctuations. Generally, the pump’s outlet valve should not be opened or closed suddenly, as doing so could cause the flow rate to increase abruptly and the pressure to drop sharply
Under normal circumstances, in a centrifugal pump, the outlet valve is opened after the motor starts; if the outlet valve is opened in advance, it will cause excessive current to flow through the motor, which may lead to damage to the motor.
We have encountered this situation as well; we are hoping for guidance from those with more experience. Our approach is to open the warm-up valve first before starting the pump, and then close it after it has started running； When shutting down the pump, do so with the outlet valve nearly closed (at about 2–3 turns), i.e., shut the pump completely ；
Use flexibility – don’t apply rules rigidly. Centrifugal pumps won’t damage the equipment like reciprocating pumps do, so you can adjust the operating parameters as needed; however, it’s still important to grasp the basic principles.
In this case, the outlet valve can be opened slightly to start the pump. If the pump has a high power rating, soft starting can be considered.