Seeking advice on abnormal noises in centrifugal pumps
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Has anyone encountered this situation? 1. Hot water pump, centrifugal type; there are abnormal noises inside the pump, and the temperature of the pump body is over 80 degrees. Vaporization and vacuum formation are suspected as the cause. But when the pump was switched off, as soon as the valve of the standby pump was opened, the abnormal noise from the main pump disappeared; when the valve of the standby pump was closed again, the noise reappeared. Why is that? The bearing temperature and vibration are both normal. 2. It’s still this pump; the pump body is extremely hot, while the cooling water inlet and outlet water are not hot. I suspect there might be a blockage in the water flow, but the small impeller in the return water sight glass is still rotating quite fast. What’s going on? I can only think that the water flow might be too fast, leaving no time for the temperature to rise, and there is too much heat inside the pump to be carried away. Are there any other possibilities?
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Is the pump operating at a low flow rate that is away from the rated flow point?
It might be due to insufficient flow, resulting in cavitation.
The inlet pipeline is too small, causing cavitation; try making it larger and see
Is there no check valve at the pump outlet? As soon as the valve of the standby pump was opened, before the pump itself started running, the abnormal noise from this pump disappeared. This indicates circulation between the two pumps, with water returning from the standby pump to the inlet of this pump, thereby preventing cavitation caused by insufficient inlet pressure and flow.
It might be due to insufficient incoming traffic
With cavitation occurring, doesn’t the vibration change at all?
Is the pump body vibrating heavily? Have you tried stopping and starting again?
The inlet filter is clogged; cleaning it will fix the issue.
I wasn’t sure if there’s a check valve; I’ll take a look when I have time. However, it wasn’t the standby pump valve that was opened; the standby pump itself wasn’t started. It was only after the standby pump was started and its outlet valve was opened that the abnormal noise from the main pump disappeared