Reasons for low pressure in centrifugal pumps
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The inlet filter of the backup pump is fine; the gaskets have been replaced, but the pressure remains slightly low and is gradually dropping. The two pumps have been swapped positions, and now both are working properly. What could be the reason for this?
Inadequate exhaust before startup, numerous bends in the inlet pipeline, and varying lengths of the pipelines.
If the check valve leaks, won’t the backup pump start running in reverse? It shouldn’t be possible
Sometimes, a slight leak is not sufficient to reverse the pump. I’m not sure how your pump is used in the field; have you encountered pressure drops caused by the inlet check valve getting stuck and failing to open? There are also inhalation valves that have been installed with the opening direction reversed. . . . .
In most cases, it is caused by internal leakage in the check valve. Check the check valve.
Low pump pressure is related to the opening degree of the outlet valve, impeller wear, and ring wear; a low pressure level requires disassembly for inspection
It could be caused by the gap between the impeller mouth ring and the volute
Agree with the opinion above – it’s possible that it’s caused by the gap between the impeller mouth ring and the volute”
After changing the position, things improved, which indicates that there is no problem with the pump itself. The issue might lie in incomplete filling of the pump; if there are bends in the inlet pipeline, it’s difficult to remove all the air at once, so it’s necessary to run the pump several times more to fill it thoroughly.