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Causes and countermeasures of common failures of centrifugal pumps

Data: 2021-01-07

Source:

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Causes and countermeasures of common failures of centrifugal pumps

1. The pump water is slow


Reason: The gap between the front liner and the impeller is large, and the water outlet pipe cannot seal the air and empty completely.

Solution: adjust the gap, adjust the water outlet pipe, install a vacuum device.

2. Low water pressure and flow


Reason: There is air in the pump, the gap between the impeller and the front liner is large, the clutch is not closed tightly, and the impeller or liner is worn.

Solution: Empty the gas in the pump, adjust the clearance, adjust the clearance of the clutch friction plate, and replace the impeller or liner.

3. Fast pump wear


Reasons: poor construction environment (large particles), long transportation distance, and long water inlet pipeline.

Solution: Replace the battlefield, add afterburners, shorten the length of the inlet pipe to reduce cavitation.

4. Water pump vibration or abnormal sound


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

Solution: Adjust the concentricity, test the balance of the impeller, and replace the bearing.

Case A: The vibration frequency is 0-40% of the working speed. Excessive bearing clearance, loose bearing bushes, impurities in the oil, poor oil quality (viscosity, temperature), oil foaming due to air or process liquid, poor lubrication, and bearing damage.

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

Case B: The vibration frequency is 60%-100% of the working speed, or the seal gap is too large, the retainer is loose, and the seal is worn.

Solution B: Check, adjust or replace the seal;

Case C: The vibration frequency is 2 times the working speed, misalignment, loose coupling, friction of sealing device, shell deformation, bearing damage, support resonance, thrust bearing damage, shaft bending, poor fit.

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

Case D: The vibration frequency is n times the working speed. Pressure pulsation, misalignment, shell deformation, seal friction, support or foundation resonance (public number: pump housekeeper), pipeline and machine resonance; reinforcement of foundation or pipeline; vibration frequency is very high. Shaft friction, seals, bearings, imprecision, bearing jitter, poor shrink fit, etc.

5. The pump does not absorb water


Reasons: insufficient filling and diversion of water, inability to discharge the air in the pump, air leakage in the suction pipe, large clearance between the front liner and the impeller.

Solution: Continue to infuse the water diversion, check whether the pipeline leaks, adjust the gap between the impeller and the front liner.

6. The impeller journal wears fast


Reasons: low head of the high-pressure water pump, misalignment of packing, and misalignment between the pump shaft and the back cover.

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


7. Interrupted after pump discharge


Reason: air leakage in the suction pipe

Solution: Check the suction side pipe connection and stuffing box sealing;

8. Bearing heating


Reason: The scraping of the bearing pads does not meet the requirements.

Solution: Re-repair or replace the bearing pad.

9. Shaft seal heating


Reason: The packing is too tight or rubbed.

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

10. Large rotor movement


Reason: improper operation, operating conditions far away from pump design conditions.

Solution: Strictly operate, so that the pump always runs near the design conditions;

12. Other circumstances


Case A: The pump is stuck. Solution: Check the coupling by turning it by hand, disassemble it if necessary, and eliminate the malfunction of the moving and static parts.

Case B: The suction side gas is not exhausted when the pump is primed. Solution: request to refill the pump;

Case C: The suction side is suddenly blocked by foreign objects. Solution: stop the pump to handle foreign matter;

Case D: Inhale a lot of gas. Solution: Check if there is a vortex at the suction inlet and if the submerged depth is too shallow.

Case E: The resistance loss increases. Solution: Check the pipeline and check valve and other obstacles;

Case F: The casing and impeller wear rings are worn too much. Solution: Replace or repair the wear ring and impeller;

Case G: Leakage from other parts. Solution: check the shaft seal and other parts;

Case H: The pump impeller is blocked, worn, and corroded. Solution: cleaning, inspection, and replacement.

Case I: The bearing clearance is too small. Solution: readjust the bearing clearance or scrape;

Case J: The amount of lubricating oil is insufficient and the oil quality is poor. Solution: increase the amount of oil or replace the lubricating oil;

Case K: The bearing is poorly assembled. Solution: Check the bearing assembly condition as required to eliminate the unqualified factors;

Case L: The cooling water is disconnected. Solution: check and repair;

Case M: The bearing is worn or loose. Solution: Repair the bearing or scrap it.

Case N: The oil slinger ring is deformed, the oil slinger ring cannot be rotated, and no oil is applied. Solution: update the slinger ring;

Case P: The water seal ring and the water seal pipe are misaligned. Solution: recheck the alignment;

Situation Q: Poor flushing and cooling. Solution: Check the flushing cooling circulation pipe;

Situation R: The balance is not smooth. Solution: clear the balance pipe;

Case S: The material of the balance plate and the balance plate seat does not meet the requirements. Solution: Replace the balance plate and balance plate seat with materials that meet the requirements.
The above is summarized by Paragon, the exporter of centrifugal pumps, please contact us for more detailed information.