Common pump failures and their solutions

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Common Faults of Pumps and Their Solutions
Serial Number | Fault Symptoms | Causes | Solutions
1 | Large fluctuations in the reading of the pressure gauge at the pump outlet, as well as fluctuations in the ammeter reading; noises coming from within the pump body and pipelines; significant decrease in the flow rate at the pump outlet | 1. Air leakage in the pump’s suction pipeline
2. Blockage in the inlet pipeline or low valve opening
3. Insufficient inlet pressure
4. High temperature of the medium, causing water vaporization
5. Low temperature of the medium, resulting in high viscosity
6. Blockage in the impeller
7. Motor running in reverse | 1. Remove air from inside the pump
2. Increase the opening of the inlet valve or clear the pipeline
3. Raise the inlet pressure
4. Slightly lower the temperature of the medium
5. Slightly reduce the viscosity of the medium
6. Contact a mechanic for inspection and repair
7. Have an electrician check it

2 | The bearing housing is abnormally hot to the touch; ammeter reading is high | 1. Insufficient or interrupted cooling water, or too high temperature of the cooling water
2. Insufficient or excessive lubricating oil
3. Damaged bearings or abnormal bearing clearance
4. The oil slinger is no longer functional
5. Water enters the bearing housing, causing the lubricating oil to become emulsified and contaminated with debris
6. Excessive load on the pump | 1. Provide more cooling water
2. Add lubricating oil or adjust its level to 1/2–2/3
3. Contact a mechanic for repair
4. Contact a mechanic for repair
5. Replace the lubricating oil in the bearing housing
6. Reduce the load according to the process requirements

3 | Vibration of the centrifugal pump | 1. Air present inside the pump or in the suction pipeline
2. Suction pipe pressure is less than or close to the vaporization pressure
3. Unbalanced rotor
4. Damaged bearings or excessive bearing clearance
5. The pump and motor are not aligned properly
6. Collision or friction between the rotor and stator components
7. Loose impeller
8. Debris present in the inlet pipe, impeller, or inside the pump
9. Resonance in the pump’s foundation | 1. Refill the pump and remove air from inside the pump or pipelines
2. Increase the suction pressure
3. Rebalance the rotor
4. Replace the bearings
5. Realign the pump and motor
6. Realign the rotor components
7. Inspect the impeller
8. Remove debris
9. Eliminate resonance in the foundation

4 | Cavitation in the centrifugal pump | 1. Air present inside the pump or in the conveyed medium
2. Too low liquid level in the suction container
3. Too low suction pressure
4. Obstructions in the suction pipe
5. Damaged impeller, resulting in reduced suction capacity | 1. Refill the pump and remove air from the pipelines
2. Raise the liquid level in the container
3. Increase the suction pressure
4. Clean the suction pipe
5. Inspect and replace the impeller

5 | The shaft of the centrifugal pump gets stuck; high temperature in the bearing housing; abnormal noise and severe vibration from the pump; lubricating oil contains metal particles; increased current leading to tripping | 1. Insufficient or no lubricating oil in the oil tank
2. Poor quality of lubricating oil, containing impurities or being emulsified due to water
3. Interruption or insufficient cooling water, causing high bearing temperatures
4. Poor quality of the bearings or fatigue due to prolonged operation | Switch to a backup pump immediately; stop the operating pump; inform the control room; contact a mechanic for repairs

6 | Seal leakage | 1. Incorrect selection or installation of the sealing material
2. Worn-out sealing material or loose gland
3. Damaged mechanical seal
4. Insufficient cooling water or seal oil in the seal chamber
5. The pump has been running under vacuum for a long time | 1. Select and install the sealing material as specified
2. Contact a mechanic to replace the sealing material or tighten the gland
3. Contact a mechanic to repair the mechanical seal
4. Adjust the amount of cooling water or seal oil in the seal chamber
5. If the pump is running under vacuum, take measures to address that issue

7 | The centrifugal pump cannot be rotated | 1. Heavy oils have solidified (e.g., residue oil)
2. Long-term lack of rotation, resulting in sticking
3. Damaged or stuck pump components
4. Severe bending of the shaft
5. Excessively tight packing in the stuffing box | 1. Purge and preheat the pump
2. Increase the frequency of rotation (to preheat the pump)
3. Contact a mechanic for repair
4. Contact a mechanic to replace the shaft
5. Contact a mechanic to loosen the packing gland or increase the frequency of rotation

8 | Outlet pressure exceeds the specified limits | 1. Blockage in the outlet pipeline
2. The outlet valve plate has fallen off (or is open to a small degree)
3. Faulty pressure gauge
4. Excessively high pressure at the pump inlet | 1. Address the issues with the outlet pipeline
2. Inspect and replace the valve plate
3. Replace the pressure gauge
4. Identify the cause and reduce the inlet pressure