Fault Finding Centrifugal Pumps – Step by Step guide

Is your centrifugal pump giving you problems?

The guidelines below might help or at least eliminate some of the more usual problems we experience in a callout:

1. If the centrifugal pump is not primed – re-prime the pump and check that the pump and suction line is full of fluid.
2. The suction line is clogged – remove the obstructions.
3. If the impeller is clogged – backflush the pump to clean the impeller or remove and clean.
4. The shaft is rotating in the wrong direction – change rotation according to the direction indicated by the arrow on the casing.
5. If the foot valve or suction pipe opening is not submerged enough – ensure adequate submersion and use a baffle if suffering vortices.
6. If the suction lift is too high – shorten the suction pipe, and relocate the pump closer to the source.

The pump is not producing the rated flow or head:

1. If the casing gasket or O Ring has an air leak – replace the gasket or O ring.
2. If the stuffing box has an air leak – replace or re-adjust the packing or mechanical seal.
3. The impeller is partially clogged – back flush to clean or remove to clean.
4. The clearance between the impeller and casing is excessive – adjust the impeller clearance.
5. The suction head is insufficient – ensure the suction line valve is fully open and the line unobstructed.
6. If the impeller is worn or broken – inspect and replace.

The pump starts and then stops pumping

1. The pump is improperly primed – re-prime the pump.
2. The suction line has air or vapour pockets – re-arrange the piping to eliminate air pockets.
3. The suction pipe has an air leak – repair the leak.

The bearings are running hot:

1. The pump and driver are aligned improperly – realign the pump and driver.
2. The lubrication has been applied improperly – check the lubrication for suitability and level
3. The lubrication is cooled improperly – check the cooling system.

The pump is noisy or vibrates:

1. The pump and driver are aligned improperly – realign the pump and driver
2. The impeller is partially clogged – backflush or remove and clean
3. If the impeller or shaft is broken or bent – replace the impeller or shaft as necessary
4. The foundation is not rigid – tighten the hold-down bolts of the pump and motor or adjust stilts
5. The bearings are worn – replace
6. The suction/discharge piping is not anchored/supported adequately – anchor/support correctly
7. The pump is cavitating – locate and correct the problem

There is excessive leakage from the stuffing box:

1. The packing gland is adjusted improperly – tighten the gland nuts
2. The stuffing box is packed improperly – check or replace the packing
3. The mechanical seal parts are worn or broken – replace parts or seal
4. The mechanical seal is overheating – check the lubrication and cooling lines
5. The shaft or sleeve is scored – machine or replace

To check if your problem is motor-related – Read our post on Pump Motor Overheating – Fault Finding Basics

Contact ESI Technologies Group if your problem is still not resolved and we will help you!