A question regarding centrifugal pumps in actual operation.
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In the desalination system of our plant, since the water supply for the raw water centrifugal pump comes from water pumped up from deep wells, and the water pressure does not meet the requirements for the inlet pressure of the raw water pump, the manufacturer reduces the size of the inlet valve of the raw water pump in order to meet the standards. This adjustment has to be made every time the system is started up. Is this practice acceptable?
The primary water pump should have a closed impeller, and there are requirements regarding the inlet water pressure
Then the components all have requirements regarding pressure and temperature; but if the pump is stopped with the inlet valve fully open, there is no need to close it partially before starting the pump again. If you are concerned about overpressure at the outlet, you can slightly open the outlet and start the pump. Regardless of the inlet opening size, the head is the same at zero flow rate.
Sure, you can try opening the inlet valve fully; if there are no problems, it can remain open. With centrifugal pumps, the main concern is cavitation caused by low inlet pressure. As long as the pressure is high enough and the flow rate does not exceed the current limit, there should be no issues, and the outlet valve can be used to regulate it.