Starting operation of a centrifugal pump
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Hello everyone. I have a question: before starting the centrifugal pump each time, the experienced workers always ask that the outlet valve be opened a little first. But if high-pressure material is connected downstream, won’t this cause backflow? Although there is a check valve, it can’t be guaranteed that the check valve is safe, right?
A centrifugal pump should be started with the outlet valve closed; it is also acceptable to open the outlet valve slightly first, in order to prevent excessive pressure buildup.
1. Opening the outlet valve slightly helps to balance the pressure before and after the outlet valve, facilitating its opening； 2. Prevent pressure buildup in the pump ；
1. Opening the outlet valve slightly helps to balance the pressure before and after the outlet valve, facilitating its opening； 2. Prevent pressure buildup in the pump
I think on the one hand, the pump outlet has not only an outlet valve but also a check valve. On the other hand, if there is no feed, how can pressure be generated downstream?
We follow the same procedure here, but it applies only to high-speed, high-pressure pumps; ordinary centrifugal pumps are basically operated strictly in accordance with the established procedures. Personally, I feel that in high-pressure and high-speed pumps, the pressure difference between the inlet and outlet is generally quite large. By opening the outlet valve slightly, it is possible to reduce the excessive pressure ratio at the pump’s (or impeller’s) inlet and outlet at the moment the pump starts up; this should have some positive effects on the stress on the pump shaft, as well as on the pump’s vibration and temperature rise The premise is that the outlet check valve is working fine.
As long as the pump’s impeller does not rotate in reverse, there is no problem.
It is best to close the outlet valve completely, and then slowly open it once the pump starts running
If there is a certain pressure in the tank downstream