Slurry pump troubleshooting: ten symptoms explained

Slurry pump faults tend to repeat. The list below works through the symptoms we are asked about most often, in the order it is worth checking them. It assumes the pump is correctly selected; if the duty itself has changed, start with a re-selection instead.

No discharge, and the gauges fluctuate

The suction line is probably not fully primed, partly blocked, or drawing air at the gland or at an instrument connection. Prime the casing, clear the line, and check the packing is wet and correctly compressed.

No discharge, with a high vacuum reading

The suction is being starved: a closed or silted suction valve, excessive pipe resistance, or the pump is installed too high above the liquid level. Open and clear the valve, review the suction layout, and reduce the installation height.

No discharge, with pressure on the gauge

The pump is generating head but the flow has nowhere to go: an obstruction in the discharge line, a blocked impeller passage, or a drive running below its rated speed.

The pump will not turn

Hard sediment has set in the volute, or the discharge valve is passing and letting slurry settle back into the casing. Clear the deposit and overhaul or replace the discharge valve.

Low flow with everything apparently open

Work through it in order: blocked impeller or pipework, a worn impeller and worn liners (the clearance opens and the flow drops off), a drive running slow, air ingress, or a duty point where the required head is higher than the pump can produce. Measuring the wear-part clearance is the step most often skipped.

Motor overload

Usually the pump is running further out on its curve than intended, because the actual head is lower than the design head — so the flow, and the power, rise. The other common cause is a motor sized on water duty for a heavy slurry. Throttle the discharge to bring the duty point back, and re-check the motor against the slurry density.

Vibration

Cavitation, a partly blocked impeller passage, coupling misalignment, or a loose foundation. Check in that order: adjust the discharge valve, clean the impeller, realign, then tighten the foundation.

Short packing life

Either the packing grade is wrong for the slurry, or the gland sealing water is missing. Dry packing in an abrasive slurry will not last.

Oil leakage from the bearing housing

Oil level too high, a failed seal, or an assembly error. Correct the level first — overfilling is more common than a genuine seal failure.

Wear parts disappearing faster than expected

Look at the particle shape and the duty point before blaming the material. Running a pump beyond its design flow accelerates wear dramatically, and sharp coarse solids will consume an alloy liner that is perfectly adequate for fine tailings.

What to send us

Model and serial number, the duty point, running hours, and a photograph of the worn wet end. From that we can usually say whether the material choice, the duty point or the installation is responsible.