Seeking advice on discoloration of the pump shaft and impeller position in a single-stage cantilever centrifugal pump

If the pump shaft and impeller of a single-stage cantilever centrifugal pump change color, it may be caused by the following reasons: 1. After long periods of use, the surfaces of the pump shaft and impeller become severely worn, resulting in localized discoloration. 2. During operation of the pump, foreign objects entered the pump, where they rubbed against the pump shaft and impeller, generating high temperatures that caused localized discoloration. 3. The impeller and pump shaft were not installed correctly, resulting in friction between the impeller and the pump shaft during rotation, which caused localized discoloration. To solve this problem, it is first necessary to determine the cause of the discoloration, and then inspect and repair the pump. The following measures can be taken: 1. Clean and inspect the pump to rule out the possibility of foreign objects entering. 2. Check the surface condition of the pump shaft and impeller; if the wear is severe, new parts need to be replaced. 3. Verify whether the impeller and pump shaft are installed correctly; if there are any issues, they need to be readjusted. 4. Avoid using low-quality lubricants or improper usage methods to ensure the proper operation of the pump shaft and impeller. In short, to maintain the good condition of the pump shaft and impeller in single-stage cantilever centrifugal pumps, it is necessary to pay attention to regular maintenance and inspections, so as to identify problems promptly and address them in a timely manner. .

This color is only formed at high temperatures; it could be due to a material issue, a medium-related problem, or loose coupling between the impeller and the shaft, as well as friction between the shaft and the impeller

Thank you for your reply. The impeller is not loose; it seems that the positions of the pump shaft and the impeller, as well as those of the mechanical seal bushings, have been exposed to high temperatures. I’m not sure what could be the cause

It doesn’t seem to be there any signs of friction on the pump shaft. According to you, the impeller is in contact with the shaft sleeve of the mechanical seal; it’s possible that the mechanical seal was misaligned during installation, which led to friction and resulting heat generation. The mechanical seal can be reinstalled as required.

Thank you for the reply. Both the mechanical seal shaft sleeve and the impeller are connected by keys, with no signs of looseness