Decanter Centrifuge Troubleshooting: Causes & Fixes

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Problems on this page:

Poor separation or cloudy effluent Vibration Torque or differential overload Wet cake Main bearings running hot Flocculant system problems Feed tube blockage Belt drive or motor problems Gearbox oil problems Foam in the centrate

Poor separation or cloudy effluent

Hits OEE: Quality

Symptoms: Wet cake or cloudy liquid, off-spec separation, carryover.

Wrong differential/pond settings

Tune bowl speed, differential and pond depth for the feed.

Feed rate or flocculant off

Adjust feed rate; optimise polymer/flocculant dosing.

Worn scroll or tiles

Inspect and rebuild the scroll wear surfaces.

Prevention: Correct process setup, dosing control, scroll wear checks.

Vibration

Hits OEE: Availability

Symptoms: High vibration alarm, noise, risk of trip or damage.

Imbalance from uneven cake build-up

Flush/clean the bowl; review feed consistency.

Bearing wear

Check and replace main bearings.

Scroll or bowl damage

Inspect for wear/damage; rebalance after rebuild.

Prevention: Cleaning regime, bearing condition monitoring, balance checks.

Torque or differential overload

Hits OEE: Availability

Symptoms: Backdrive/torque overload trips, scroll struggles to convey cake.

Solids overload or heavy feed

Reduce feed rate/solids; adjust differential.

Compacted or sticky cake

Tune pond and dosing; flush as needed.

Gearbox or backdrive fault

Inspect the gearbox/backdrive and lubrication.

Prevention: Feed/solids control, process tuning, gearbox maintenance.

Wet cake

Hits OEE: Quality

Symptoms: Cake leaves wetter than the next process can take.

Pond depth wrong for the product

Adjust the weir plates as the maker describes.

Differential speed too high

Lower the differential so the cake stays longer.

Flocculant dose wrong

Check and adjust the polymer dose.

Prevention: Cake dryness tested each shift.

Main bearings running hot

Hits OEE: Availability

Symptoms: Bearing temperature alarms on the main bearings.

Lubrication wrong or missed

Grease or oil as the maker specifies.

Bearing wear

Check vibration and plan replacement.

Cooling poor

Check the cooling around the bearing housings.

Prevention: Bearing temperatures trended.

Flocculant system problems

Hits OEE: Quality

Symptoms: Separation is poor although the machine settings are right.

Polymer made up at the wrong strength

Check the concentration and mixing time.

Dosing pump fault

Check the pump.

Polymer solution too old

Use solution within its working life.

Prevention: Polymer use per tonne tracked.

Feed tube blockage

Hits OEE: Availability

Symptoms: Feed backs up and the machine trips on high torque or feed alarm.

Rags or solids in the feed

Screen or macerate the feed.

No flush at stop

Flush the feed tube at every stop.

Build-up in the tube

Clean the tube.

Prevention: Flush sequence checked.

Belt drive or motor problems

Hits OEE: Availability

Symptoms: Belt slip, speed alarms, drive faults.

Belt tension low

Set the tension.

Worn belts

Replace them as a set.

Drive fault

Read the drive alarms.

Prevention: Belt checks weekly.

Gearbox oil problems

Hits OEE: Availability

Symptoms: The gearbox runs hot, leaks oil, or the oil darkens quickly.

Oil change overdue

Change the oil at the maker's interval.

Seals worn

Replace the seals.

High torque running

Check the solids loading and the differential.

Prevention: Gearbox oil checked on the route.

Foam in the centrate

Hits OEE: Quality

Symptoms: Foam builds in the centrate tank and spills.

Air drawn in at the feed

Check the feed tank level and pump suction.

Polymer overdose

Reduce the dose.

Open fall at the centrate discharge

Reduce the fall.

Prevention: Centrate checks on the round.

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

Related equipment guides: mixer agitator · homogeniser · reactor · granulator · disc stack separator · DAF unit · wine press

Stop the same fault coming back

Recurring decanter centrifuge 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.

Book a Fabrico demo

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