Maintenance During Operation Of Centrifugal Pump

Jan 17, 2021

1. Lubrication

During the operation of the centrifugal pump, the conveyed medium, water and other substances may escape into the oil tank and affect the normal operation of the pump. Therefore, the quality and oil level of the lubricant of the centrifugal pump should be checked frequently. To check the quality of lubricants, visual observation and regular sampling and analysis can be used. The amount of lubricating oil can be seen from the oil level mark.

The oil should be changed once after the new pump has been running for a week, and the oil should also be changed for the pump whose bearing has been changed during overhaul. Because foreign matter enters the oil during the running-in of the new bearing and the shaft, the oil must be changed. Change the oil every quarter thereafter. The grease and lubricating oil used must meet the quality requirements.

2. Vibration

During the operation of the pump, due to the poor quality of parts and repairs, improper operation or the influence of pipeline vibration, vibrations will often occur. If the vibration exceeds the allowable value, stop for maintenance to avoid damage to the machine.

3. Bearing temperature rise

During the operation of the pump, if the bearing temperature rises quickly, and the bearing temperature is too high after the temperature rise is stable, it indicates that the bearing has a problem in manufacturing or installation quality; or the quality, quantity or lubrication method of the bearing lubricating oil does not meet the requirements. If it is not handled in time, the bearing may burn out. The allowable temperature of centrifugal pump bearings is: sliding bearings <65℃; rolling bearings <70℃. The allowable value refers to the allowable range of bearing temperature after a period of operation. For newly replaced bearings, the temperature of the bearing will rise higher at the beginning of operation, and after a period of operation, the temperature will drop a little and stabilize at a certain value.

4. Operating performance of centrifugal pump

During the operation of the pump, if there is no change in the source of the liquid, the opening of the valve on the inlet and outlet pipeline has not changed, but the flow rate or inlet and outlet pressure has changed, indicating that there is a fault in the pump or pipeline. It is necessary to quickly find out the cause and eliminate it in time. Otherwise, it will cause undesirable consequences.

① When the pipeline centrifugal pump is started, in order to avoid overloading of the motor, the outlet valve should be closed, and then opened slowly after the pump is started. In this way, when the motor is started, the starting load is superimposed with the high power required by the pump when the outlet valve is fully opened, which may cause the motor to be overloaded.

② Only the pump cavity is filled with liquid (to avoid dry friction of the seal ring, shaft seal and mechanical seal), the centrifugal pump is allowed to run for a short time when the outlet valve is closed, unless the limited liquid in the pump cavity is under the action of the rotating impeller, The temperature rises quickly and brings some bad effects to the pump, but it has no bad effect on the motor, and the load of the motor is lighter at this time.

③ During operation, any set of flow and head within the performance range of the centrifugal pump can be obtained by adjusting the opening of the outlet valve. However, when the pump is running at the design operating point, its efficiency is the highest; the farther away from the design operating point, The lower the efficiency.