Common Faults Of Centrifugal Pumps - Solutions That Need To Be Known

Nov 18, 2024

1. Slow water filling of centrifugal pump

Reason: The gap between the front lining plate and the impeller is large, the water outlet pipe cannot seal the air, and it can be fully emptied.

Solution: Adjust the gap, adjust the water outlet pipeline, and install a vacuum device.

2. Low outlet pressure and flow rate

Reason: There is air inside the centrifugal pump, there is a large gap between the impeller and the front lining plate, the clutch is not tightly closed, and the impeller or lining plate is worn.

Solution: Evacuate the gas inside the centrifugal pump, adjust the clearance, adjust the clutch friction plate clearance, and replace the impeller or lining plate.

3. Centrifugal pumps wear out quickly

Reason: Poor construction environment (large particles), long transportation distance, and long inlet pipeline.

Solution: Replace the sand field, add a booster unit, shorten the length of the inlet pipe to reduce cavitation.

4. Centrifugal pump vibration or abnormal noise

Reason: The centrifugal pump shaft is not concentric with the diesel engine (or motor), the impeller is unbalanced, and the bearings are damaged.

Solution: Adjust concentricity, conduct balance testing on impeller, and replace bearings.

Scenario A: The vibration frequency is 0-40% of the operating speed. Excessive bearing clearance, loose bearing shells, impurities in the oil, poor oil quality (viscosity, temperature), oil bubbles caused by air or process fluids, poor lubrication, and bearing damage.

Solution A: After inspection, take corresponding measures such as adjusting the bearing clearance, removing impurities from the oil, and replacing with new oil;

Scenario B: The vibration frequency is between 60% and 100% of the operating speed, or the sealing gap is too large, the protective ring is loose, and the seal is worn.

Solution B: Check, adjust or replace the seal;

Scenario C: The vibration frequency is twice the working speed, which is not centered. The coupling is loose, the sealing device is rubbed, the shell is deformed, the bearing is damaged, the support resonance is affected, the thrust bearing is damaged, the shaft is bent, and there is poor fit.

Solution C: Check, take corresponding measures, repair, adjust or replace;

Scenario D: The vibration frequency is n times the operating speed. Pressure pulsation, misalignment, shell deformation, sealing friction, support or foundation resonance, pipeline and machine resonance; Strengthening foundations or pipelines; The vibration frequency is very high. Shaft friction, sealing, bearings, lack of precision, bearing vibration, poor contraction fit, etc.

5. Centrifugal pump does not absorb water

Reason: Insufficient water injection, inability to discharge air from the centrifugal pump, air leakage in the suction pipe, and large gap between the front lining plate and impeller.

Solution: Continue to inject water, check if there is any air leakage in the pipeline, and adjust the gap between the impeller and the front lining plate.

6. The impeller journal wears out quickly

Reason: Low head of high-pressure centrifugal pump, misalignment of packing, and misalignment of centrifugal pump shaft and back cover.

Solution: Replace the high-pressure centrifugal pump with a head higher than that of the single-stage centrifugal pump, replace the packing, and adjust the concentricity.

7. Interruption after centrifugal pump discharge

Reason: Air leakage in the suction pipeline

Solution: Check the connection of the suction side pipeline and the sealing condition of the packing box;

8. Bearing overheating

Reason: The scraping and grinding of the bearing pads do not meet the requirements.

Solution: Repair the bearing pads or replace them.

9. Shaft seal heating

Reason: The packing is pressed too tightly or rubbed.

Solution: Loosen the packing and check the water seal pipe;

10. Large rotor movement

Reason: Improper operation, operating conditions far from the design conditions of the centrifugal pump.

Solution: Strictly operate to ensure that the centrifugal pump always operates near the design working conditions;

11. Other situations of centrifugal pump

Scenario 1: The centrifugal pump is stuck.
Solution: Check the coupling by manually turning it, and if necessary, disassemble it for inspection to eliminate any faults in the moving and stationary parts.

Scenario 2: When filling the centrifugal pump, the gas on the suction side is not completely discharged. Solution: Request to refill the centrifugal pump;

Scenario 3: The suction side is suddenly blocked by foreign objects.
Solution: Stop the centrifugal pump to handle foreign objects;

Scenario 4: Inhaling a large amount of gas.
Solution: Check if there are eddies at the suction port and if the submergence depth is too shallow.

Scenario 5: Increased resistance loss.
Solution: Check for obstacles such as pipelines and check valves;

Scenario 6: Excessive wear on the wear-resistant rings of the shell and impeller.
Solution: Replace or repair the wear-resistant ring and impeller;

Scenario 7: Leakage in other parts.
Solution: Check the shaft seal and other parts;

Scenario 8: The impeller of the centrifugal pump is blocked, worn, and corroded.
Solution: Clean, inspect, and replace.

Scenario 9: The bearing clearance is too small.
Solution: Adjust the bearing clearance or scrape it;

Scenario 10: Insufficient lubricating oil quantity and poor oil quality. Solution: Increase oil volume or replace lubricating oil;

Scenario 11: Poor assembly of bearings.
Solution: Check the assembly of bearings as required and eliminate non compliant factors;

Scenario 12: Cooling water circuit breaker.
Solution: Inspection and repair;

Scenario 13: Bearing wear or looseness.
Solution: Repair bearings or scrap them.

Scenario 14: The oil slinger is deformed, unable to rotate and carry oil.
Solution: Update the oil slinger ring;

Scenario 15: The water seal ring is misaligned with the water seal pipe.
Solution: Recheck alignment;

Scenario 16: Poor flushing and cooling.
Solution: Check and flush the cooling circulation pipe;

Scenario 17: Imbalance.
Solution: unclog the balance pipe;

Scenario 18: The material of the balance disk and balance disk seat does not meet the requirements.
Solution: Replace the balance disc and balance disc seat with materials that meet the requirements.