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!

Let's Connect!

Get in touch with our dedicated team. We are here to help!