esperantes
Electrical
- Dec 11, 2020
- 25
Hello Forum members,
I have little knowledge in pump engineering and would like to have your honest judgment. We are having an issue with a 2900 rpm centrifugal pump which we just purchased. The pump is designed to operate at 12 bar 5.1 m NPSH. Our application is such that we have sometimes to throttle the discharge valve to get 8 bar on the discharge line. We understand that this is not an effective way to operate the pump but we had been operating this way for years with the old pump without any issue. The only reason we replaced the old pump was that the impeller was worn out after 30 years of good service. When we operated the new pump with the discharged valve throttled the double ball bearings on the pump failed after two days of operation. The bearings are oil lubricated, and we could see that the thermal degradation of the oil caused the bearings to fail. The manufacturer is claiming that a throttled valve condition caused lot of stress on the pump shaft and bearings, due to excessive internal circulation in the pump volute casing and this caused the bearings to fail. They are now proposing to put a variable speed drive to reduce the speed of the pump. This is obviously a very expensive solution.
Any advice?
Thank You
Esperantes
I have little knowledge in pump engineering and would like to have your honest judgment. We are having an issue with a 2900 rpm centrifugal pump which we just purchased. The pump is designed to operate at 12 bar 5.1 m NPSH. Our application is such that we have sometimes to throttle the discharge valve to get 8 bar on the discharge line. We understand that this is not an effective way to operate the pump but we had been operating this way for years with the old pump without any issue. The only reason we replaced the old pump was that the impeller was worn out after 30 years of good service. When we operated the new pump with the discharged valve throttled the double ball bearings on the pump failed after two days of operation. The bearings are oil lubricated, and we could see that the thermal degradation of the oil caused the bearings to fail. The manufacturer is claiming that a throttled valve condition caused lot of stress on the pump shaft and bearings, due to excessive internal circulation in the pump volute casing and this caused the bearings to fail. They are now proposing to put a variable speed drive to reduce the speed of the pump. This is obviously a very expensive solution.
Any advice?
Thank You
Esperantes