Common Faults of Centrifugal Pumps

1. No water discharge / Insufficient flow

Failure to pump waterCauses: Insufficient pump priming, air leakage on the suction side, clogged or stuck foot valve, excessive installation height, high resistance of suction pipeline Solutions: Reprime the pump; tighten inlet flanges and valves; clear debris from the foot valve; lower installation height; enlarge the suction pipe.

Low flow rateCauses: Worn or fouled impeller, blocked inlet filter, insufficient rotating speed, small opening of discharge valve, partial pipeline blockage Solutions: Clean and repair the impeller; clean the filter screen; check motor speed; open the outlet valve properly; unclog pipelines.

2. Insufficient head, unable to build‑up pressure

Causes: Corroded & worn impeller, cavitation caused by gas entrainment, low rotating speed, inlet & outlet pipeline leakage Solutions: Repair or replace the impeller; optimize suction conditions to avoid cavitation; inspect the motor; eliminate pipeline leakage.

3. Excessive vibration & abnormal noise

Causes: Loose anchor bolts, misalignment between pump shaft and motor shaft, unbalanced impeller, damaged bearing, cavitation, pipeline stress pulling the pump casing Solutions: Tighten foundation bolts; realign the coupling; repair the impeller; replace bearings; optimize suction conditions to reduce cavitation; add pipeline supports.

4. Overheated bearing, excessive temperature

Causes: Excessive / insufficient lubricant, deteriorated oil, damaged bearing, serious misalignment, bent shaft Solutions: Adjust oil level; replace lubricating grease; install new bearings; re‑correct shaft alignment.

5. Severe leakage at mechanical seal / packing gland

Packing seal heavy leakage: Aged packing, improperly adjusted gland tightness, worn shaft sleeve Solutions: Adjust gland compression; replace packing; repair the shaft sleeve.

Mechanical seal leakage: Worn rotating‑stationary rings, failed spring, aging sealing ring Solutions: Disassemble and replace mechanical seal spare parts.

6. Motor overload, over‑limit current

Causes: Fully‑opened outlet valve beyond working condition, excessive medium density or viscosity, foreign matter stuck in impeller, bearing seizure Solutions: Throttle the outlet valve to adjust operating condition; verify medium parameters; dismantle and clean foreign objects inside the impeller; overhaul bearings.

7. Cavitation (Typical failure)

Symptoms: Crackling noise inside pump, violent vibration, unstable flow and pressure; long‑term cavitation will damage the impeller. Causes: Too low inlet pressure, insufficient liquid level, high resistance of suction pipeline, high medium temperature Solutions: Raise liquid level, shorten suction pipeline, clean inlet strainer, lower medium temperature.