Pump operation issues
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The multi-stage vertical centrifugal pump stopped rotating during operation; upon disassembly, it was found that the motor was fine, but there were scratches on the bottom of the pump casing, and the impeller was shaking from side to side. It runs normally after being reinstalled – what’s going on here? Are the scratches and shaking normal?
Scratches on the bottom of the pump body indicate that the impeller has dropped, resulting in low friction within the pump. The back-and-forth movement of the impeller is caused by a loose impeller positioning system, which has moved out of position relative to the dowel pin.
If the problem is identified and fixed, there will be no issues
The rotor inside the pump needs to be lifted a little so that the impeller is separated from the support vanes; otherwise, friction will occur； Check whether the intermediate support of the bottom guide vanes is worn; if there is no wear, they can be used normally. If the wear is severe, the concentricity of the rotating shaft will be poor, which can easily cause the inner hole of the guide vanes to grow larger over time.
A properly functioning pump impeller experiences no friction, and of course no scratches either; it is recommended to conduct a thorough inspection and maintenance.