Overheating in centrifugal pumps can lead to premature failure, seal damage, and reduced efficiency. Below are the primary causes of overheating and their solutions.
Closed or blocked suction/discharge valves.
Clogged strainer or suction line.
Insufficient NPSH (Net Positive Suction Head).
Pump operating against a closed discharge.
✔ Ensure valves are fully open.
✔ Clean suction strainer/filter.
✔ Check NPSH available (NPSHa > NPSHr).
✔ Install a low-flow protection device (bypass or flow switch).
Misalignment (coupling, bearings, shaft).
Worn bearings causing drag.
Rubbing impeller (due to worn wear rings).
Bent shaft increasing resistance.
✔ Realign pump and motor (laser/dial indicator).
✔ Replace worn bearings and lubricate properly.
✔ Inspect and replace wear rings if clearance is excessive.
✔ Check shaft runout (max 0.05mm).
Insufficient lubricant (oil or grease).
Contaminated lubricant (water, dirt).
Wrong lubricant type (viscosity mismatch).
✔ Check oil level/grease quantity (fill to ⅓–½ of bearing housing).
✔ Drain and replace contaminated lubricant.
✔ Use manufacturer-recommended grease/oil.
Mechanical seal running dry → overheating.
Over-tightened gland packing → excessive friction.
Dry-running damage to seal faces.
✔ Ensure proper seal lubrication/cooling (flush system).
✔ Adjust packing gland for slight leakage (1-2 drops/min).
✔ Replace damaged mechanical seals.
Overloaded motor (exceeding rated current).
Voltage imbalance (single-phasing in 3-phase motors).
Incorrect motor speed (VFD misconfiguration).
✔ Check motor current (compare with nameplate rating).
✔ Test voltage phases for imbalance.
✔ Verify VFD settings (if applicable).
Cavitation (low NPSH, vapor bubbles collapsing).
Internal recirculation (pump operating at very low flow).
✔ Increase NPSH (lower pump speed, increase suction pressure).
✔ Avoid operating pump below minimum flow (install recirculation line).
Lack of ventilation around pump.
Cooling system failure (for pumps with external cooling).
✔ Improve airflow around the pump.
✔ Check cooling jackets/heat exchangers for blockages.
Check flow rate (compare with pump curve).
Monitor motor current (overload indicates mechanical resistance).
Inspect bearings & lubrication (noise, heat, vibration).
Verify alignment (coupling, shaft).
Test NPSH (avoid cavitation).
Overheating in centrifugal pumps is often due to flow issues, mechanical friction, lubrication problems, or motor faults. Regular maintenance, proper alignment, and monitoring can prevent overheating and extend pump life.
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