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Fault Finding

Pump does not deliver liquid
Pump does not deliver rated quantity
Pump does not regenerate its rated delivery pressure
Pump loses liquid after starting
Pump overloads driving unit
Excessive vibration
Bearing overheating
Bearings wear
Irregular delivery
Excessive noise

Pump does not deliver liquid
Possible Fault Remedy
  • Impeller rotating in wrong direction.
  • Pump not properly primed - air or vapour lock in suction line.
  • Inlet of suction pipe insufficiently submerged.
  • Air leaks in suction line or gland arrangement.
  • Pump not up to rated speed.
  • Reverse direction of rotation.
  • Stop pump and reprime.
  • Ensure adequate supply of liquid.
  • Make good any leaks or repack gland.
  • Increase speed.
 Pump does not deliver rated quantity
Possible Fault Remedy
  • Air or vapour lock in suction line.
  • Inlet of suction pipe insufficiently submerged.
  • Pump not up to rated speed.
  • Air leaks in suction line or gland arrangement.
  • Foot valve or suction strainer choked.
  • Restriction in delivery pipe work or pipe work incorrect.
  • Head underestimated.
  • Unobserved leak in delivery.
  • Blockage in impeller or easing.
  • Excessive wear at neck rings or wearing plates.
  • Impeller damaged.
  • Pump gaskets leaking.
  • Stop pump and reprime.
  • Ensure adequate supply of liquid.
  • Increase speed.
  • Make good any leaks or repack gland.
  • Clean foot valve or strainer.
  • Clear obstruction or rectify error in pipe work.
  • Check head losses in delivery pipes, bends and valves, reduce losses as required.
  • Examine pipe work and repair leak.
  • Remove half easing and clear obstruction.
  • Dismantle pump and restore clearances to original dimensions.
  • Dismantle pump and renew impeller.
  • Renew defective gaskets.
 Pump does not regenerate its rated delivery pressure
Possible Fault Remedy
  • Impeller rotating in wrong direction.
  • Pump not up to rated speed.
  • Impeller neck rings worn excessively.
  • Impeller damaged or choked.
  • Pump gaskets leaking.
  • Reverse direction of rotation.
  • Increase speed.
  • Dismantle pump and restore clearances to original dimensions.
  • Dismantle pump and renew impeller or clear blockage.
 Pump loses liquid after starting
Possible Fault Remedy
  • Suction line not fully primed - air or vapour lock in suction line.
  • Inlet of suction pipe insufficiently submerged.
  • Air leaks in suction line or gland arrangement.
  • Liquid seal to gland arrangement logging ring (if fitted) choked.
  • Logging ring not properly located.
  • Stop pump and reprime.
  • Ensure adequate supply of liquid at suction pipe inlet.
  • Make good any leaks or renew gland packing.
  • Clean out liquid seal supply.
  • Unpack gland and relocate logging ring under supply orifice.
 Pump overloads driving unit
Possible Fault Remedy
  • Pump gaskets leaking
  • Serious leak in delivery line, pump delivering more than its rated quantity.
  • Speed too high.
  • Impeller neck rings worn excessively.
  • Gland packing too tight.
  • Impeller damaged.
  • Mechanical tightness at pump internal
    components.
  • Pipe work exerting strain on pump.
  • Renew defective gaskets.
  • Repair leak.
  • Reduce speed.
  • Dismantle pump and restore clearances to original dimensions.
  • Stop pump, close delivery valve to relieve internal pressure on packing, slacken back the gland nuts and retighten to finger tightness.
  • Dismantle pump and renew impeller.
  • Dismantle pump, check internal clearances and adjust as necessary.
  • Disconnect pipe work and realign to pump.
 Excessive vibration
Possible Fault Remedy
  • Air or vapour lock in suction.
  • Inlet of suction pipe insufficiently submerged.
  • Pump and driving unit incorrectly aligned.
  • Worn or loose bearings.
  • Impeller choked or damaged.
  • Rotating element shaft bent.
  • Foundation not rigid.
  • Coupling damaged.
  • Pipe work exerting strain on pump.
  • Stop pump and reprime.
  • Ensure adequate supply of liquid at suction pipe inlet.
  • Disconnect coupling and realign pump and driving unit.
  • Dismantle and renew bearings.
  • Dismantle pump and clear or renew impeller.
  • Dismantle pump and straighten or renew shaft.
  • Remove pump, strengthen the foundation and reinstall pump.
  • Renew coupling.
  • Disconnect pipe work and realign to pump.
  Bearing overheating
Possible Fault Remedy
  • Pump and driving unit out of alignment.
  • Oil level too low or too high.
  • Wrong grade of oil.
  • Dirt in bearings.
  • Moisture in oil.
  • Bearings too tight.
  • Too much grease in bearing.
  • Pipe work exerting strain on pump.
  • Disconnect pipe work and re-align to pump.
  • Disconnect coupling and re-align pump and driving unit.
  • Replenish with correct grade of oil or drain down to correct level.
  • Drain out bearing, flush through bearings; refill with correct grade of oil.
  • Dismantle, clean out and flush through bearings; refill with correct grade of oil
  • Drain out bearing, flush through and refill with correct grade of oil. Determine cause of contamination and rectify.
  • Ensure that bearings are correctly bedded to their journals with the correct amount of oil clearance. Renew bearings if necessary.
  • Clean out old grease and repack with correct grade and amount of grease.
  • Disconnect pipe work and realign to pump.
 Bearings wear
Possible Fault Remedy
  • Pump and driving unit out of alignment.
  • Rotating element shaft bent.
  • Dirt in bearings.
  • Lack of lubrication.
  • Bearing badly installed.
  • Pipe work exerting strain on pump.
  • Excessive vibration
  • Disconnect coupling and realign pump and driving unit. Renew bearings if necessary.
  • Dismantle pump, straighten or renew shaft. Renew bearings if necessary.
  • Ensure that only clean oil is used to lubricate bearings. Renew bearings if necessary. Refill with clean oil.
  • Ensure that oil is maintained at its correct level or that oil system is functioning correctly. Renew bearings if necessary.
  • Ensure that bearings are correctly bedded to their journals with the correct amount of oil clearance. Renew bearings if necessary.
  • Ensure that pipe work is correctly aligned to pump. Renew bearings if necessary.
  • Refer to "Excessive Vibration"
 Irregular delivery
Possible Fault Remedy
  • Air or vapour lock in suction line.
  • Fault in driving unit.
  • Air leaks in suction line or gland arrangement.
  • Inlet of suction pipe insufficiently immersed in liquid.
  • Stop pump and reprime.
  • Examine driving unit and make good any defects.
  • Make good any leaks or repack gland.
  • Ensure adequate supply of liquid at suction pipe inlet.
 Excessive noise
Possible Fault Remedy
  • Air or vapour lock in suction line.
  • Inlet of suction pipe. Insufficiently submerged.
  • Air leaks in suction line or gland arrangement.
  • Pump and driving unit out of alignment.
  • Worn or loose bearings.
  • Rotating element shaft bent.
    Foundation not rigid.
  • Stop pump and reprime.
  • Ensure adequate supply of liquid at suction pipe inlet.
  • Make good any leaks or repack gland. Disconnect coupling and realign pump and driving unit.
  • Dismantle and renew bearings.
  • Dismantle pump, straighten or renew shaft.
  • Remove pump and driving unit, strengthen foundation.
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