Centrifugal Pump Troubleshooting: Causes & Fixes

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Problems on this page:

No or low flow Cavitation Mechanical seal leak Bearings running hot Excessive vibration or noise Pump loses prime Motor overloads or draws high current Flow and head falling over time

No or low flow

Hits OEE: Availability

Symptoms: Little/no discharge, low pressure gauge reading, process starved.

Loss of prime / air bound

Re-prime; bleed air; check suction is flooded.

Suction blockage or closed valve

Clear the strainer; confirm suction valve is open.

Wrong rotation

Verify motor rotation matches the pump arrow (check phasing).

Worn impeller/wear rings

Inspect for wear/erosion; replace impeller or wear rings.

Prevention: Strainer checks, correct valve line-up SOPs, monitor flow/pressure trend.

Cavitation

Hits OEE: Quality

Symptoms: Rattling/gravel noise, fluctuating discharge, pitting on the impeller.

Insufficient NPSH (suction too low)

Raise suction level/pressure; lower the pump or shorten suction line.

Suction restriction

Clean the strainer; remove restrictions; increase suction pipe size.

Fluid too hot / near vapour pressure

Reduce temperature or increase suction pressure.

Prevention: Design/monitor NPSH margin, keep suction lines clear, trend suction pressure.

Mechanical seal leak

Hits OEE: Availability

Symptoms: Liquid dripping at the shaft, visible weep, environment/safety concern.

Worn or cracked seal faces

Replace the mechanical seal; inspect the shaft sleeve.

Dry running

Ensure flush/lubrication to the seal; never run dry.

Misalignment/excess vibration

Align pump-motor; correct vibration causing seal wear.

Prevention: Seal flush plans, precision alignment, vibration monitoring.

Bearings running hot

Hits OEE: Availability

Symptoms: Hot bearing housing, discoloured or noisy grease, short bearing life.

Too much or too little grease

Grease with the amount and interval the maker gives; too much grease also runs hot.

Wrong or contaminated lubricant

Drain, flush and refill with the specified lubricant, and fix the seal that let dirt or water in.

Misalignment with the motor

Align pump and motor after any work and check for soft foot.

Running far from the best efficiency point

Bring the duty point back toward the best efficiency point; high radial and thrust loads heat the bearings.

Prevention: Lubrication on a route, alignment after every intervention, bearing temperature or vibration trended.

Excessive vibration or noise

Hits OEE: Availability

Symptoms: High vibration, noise, premature seal/bearing failure.

Misalignment

Laser-align the pump and motor; check soft foot.

Cavitation or operating off BEP

Restore NPSH; run nearer the best efficiency point.

Imbalance or worn bearings

Balance the impeller; replace worn bearings.

Prevention: Alignment, run near BEP, bearing/balance checks.

Pump loses prime

Hits OEE: Availability

Symptoms: The pump runs but delivers nothing, or flow stops soon after start-up.

Air leaking into the suction line

Check suction joints, gaskets and valve glands for air leaks.

Foot valve or non-return valve leaking back

Repair or replace the valve so the casing stays full.

Supply level too low for the suction lift

Raise the supply level or lower the pump, and check the level switch.

Casing not vented before start

Vent and fill the casing before start-up.

Prevention: A priming and venting step in the start-up procedure.

Motor overloads or draws high current

Hits OEE: Availability

Symptoms: The motor trips on overload, runs hot, or draws more current than its nameplate.

Pump running far out on its curve (high flow, low head)

Throttle the discharge or correct the system so the pump runs near its duty point.

Liquid denser or thicker than the pump was sized for

Check the liquid against the pump datasheet; the motor may need resizing.

Impeller rubbing or a bearing seizing

With power isolated, turn the shaft by hand and inspect for rubbing.

Impeller larger than specified

Check the impeller diameter against the datasheet.

Prevention: Motor current trended and compared with the pump curve.

Flow and head falling over time

Hits OEE: Performance

Symptoms: The pump delivers less than it used to at the same speed and the process takes longer.

Wear ring or impeller clearance opened up

Measure the clearances and replace the wear rings or impeller.

Impeller worn by abrasive solids

Inspect the impeller and consider a harder material for abrasive duty.

Impeller or strainer partly blocked

Clean the strainer and the impeller passages.

System resistance has risen

Check valve positions and pipe fouling against the original setup.

Prevention: Performance checks against the pump curve at set intervals.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Alarm codes: ABB ACS550 drive fault codes

Stop the same fault coming back

Recurring centrifugal pump stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover