Abnormal noise from the self-priming pump
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Water is pumped upstairs using surface irrigation, with a lift height of over 20 meters. However, the self-priming pump had its impeller replaced, its base was reinforced, and it was leveled as well. However, the pump head and coupling vibrate abnormally, and there is also a rattling sound. At first, I thought the mechanical seal was broken, so I had the workers take it apart to check it; they also removed the motor, and its bearings were fine as well. The water produced had almost no impurities. I’ve discussed it with the deputy head of equipment. I didn’t get any ideas. A couple of days ago, I thought there were two possibilities: the first one was that the axis was misaligned. The second issue is that there is gas in the inlet pipeline. Then I went to the site to check, and the water delivery volume of the pump was very high; it didn’t seem like there was a leak in the pipes. The cause could not be found; the pump head has been replaced. The mechanical seal has been replaced, as have the rotating and stationary rings.
Generally, mechanical noises and process-related noises should be distinguishable; try adjusting the flow rate to see what effect it has. When starting the pump, the outlet valve should be fully closed, and vibration levels should be monitored while ensuring proper pressure. It is important to determine whether the vibration at this stage is the same as that that occurs as the outlet valve is gradually opened. If it’s the same, then the issue of mechanical balance is worth paying attention to.
I went to take a look; I placed my hand on the pump head, and it vibrated quite strongly, with significant abnormal noises as well. The motor is not vibrating. The base is fixed.
It’s probably still the sound of cavitation; restart the pump and don’t open the outlet valve completely.
Is the inlet valve opened wide? Ensure thorough exhaust and drainage, then slowly open the outlet valve to reach the appropriate operating condition! Is cavitation caused by too high a medium temperature or too low a medium pressure? Is the shaft alignment satisfactory? Are there issues with the quality of the pump bearings, or is the installation and positioning of the bearings not proper? Is the rotor bent or is its dynamic imbalance too high?
I have encountered this phenomenon before as well; it is mainly due to cavitation. Is there a flow meter at the pump outlet? If the traffic is severely insufficient, a judgment can be made. It is best to keep the pump outlet valve slightly open and monitor the situation; once backpressure in the pipeline is established, everything will be normal.