TROUBLESHOOTING OF PUMPS

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1.Failure to build up pressure

Causes:

  • Loss of suction / air ingress
  • Discharge valve stuck in closed position
  • Motor inoperational
  • Internal damage due to wear & tear

Remedial Actions:

Identify cause & rectify same

2. Vibration

Causes:

  • It is because of bearing damage
  • Misalignment to coupling
  • Damage to the rotating components
  • There have also been causes of heavily clogged impellers causing excessive vibration
  • Foundation bolts weak

Remedial Actions:

Identify cause & rectify same

3. Overload & Trip

Causes:

  • Overload of the motor will occur due to the excessive resistance to motion.
  • Imbalance.
  • Bent shaft.
  • Insufficient working clearance.
  • Damaged bearing
  • Clogged impellers.

Remedial Actions:

Identify cause & rectify same

4. Drop in capacity

Causes:

  • It is usually due to worn parts (excessive clearance of wear rings)
  • Fault in prime mover (not developing correct rpm).
  • Impellers being assembled up in the wrong way, leading to the sudden drop in performance (check the direction before dismantling and confirm before re-assembly)

Remedial Actions:

Identify cause & rectify same

5. Overheating

Causes:

At low capacities, the power supplied to the pump is no longer converted in to mechanical output, which is seen as a drop in efficiency. The excess energy is seen as an increase in the temperature, which could lead to reduction in working clearances, overheating and damage to bearings and seals

Symptoms:

  • Drop in discharge pressure.
  • Rise in temperature of casing.
  • Air lock in system.
  • COP will trip on high casing temp.

Remedial Actions:

Identify cause & rectify same

6. Loss of suction of pump having positive suction head

Causes:

  • Blockage on the suction side.
  • Tank is empty.

Symptoms:

  • Suction pressure gauge shows negative pressure for blockage on suction side
  • Suction pressure gauge shows zero pressure for the empty tank

Remedial Actions:

Identify cause & rectify same

7. Loss of  the pump suction pressure having negative suction head.

Causes:

  • Blockage on the suction side.
  • Water level drops below the suction pipe.(e.g. Emergency Fire Pump)
  • Air ingress in to the pipeline through leaky flange, hole, leaky valve or leaky gland packing(common fault in bilge ballast pump’g systems)

Symptoms:

  • The suction pressure shows vacuum more than normal for blockage in the suction side
  • Suction pressure gauge shows zero for water level drop below suction line.
  • It shows zero for   air leakage.

Remedial Actions:

Identify cause & rectify same

8. Pump having less discharge pressure with discharge valve fully open.

Causes:

Water is re-circulating within the pump through worn out wear rings, pumps valve.

Symptoms:

The discharge pressure gauge shows less pressure than the normal.

Remedial Actions:

Identify cause & rectify same

9. Centrifugal pump priming unit malfunction(e.g. Emergency Fire Pump)

Causes:

Priming pump not getting sealing water.

Symptoms:

  • No air discharge from water ring primer.
  • Pump suction pressure gauge shows zero pressure.

Remedial Actions:

Identify cause & rectify same. Ensure sealing water tank is full at all times.

10. Gear pumps discharge pressure low.

Causes:

  • More clearance between the casing & the gear wheels due to erosion.
  • Suction filters clogged.

Symptoms:

Discharge pressure gauge shows low pressure than normal.

Remedial Actions:

Identify cause & rectify same. Ensure sealing water tank is full at all times.

11. Reciprocating pump having fluctuating discharge pressure.

Causes:

  • Air vessel fitted to the pump discharge line is not working properly.
  • Pressure gauge faulty

Symptoms:

Discharge pressure gauge pointer is fluctuating.

Remedial Actions:

Identify cause & rectify same

12. Reciprocating pump having suction but no discharge.

Causes:

Discharge valve in valve chest sluggish in operation.

Symptoms:

Discharge pressure gauge shows zero reading.

Remedial Actions:

Identify cause & rectify same

13. Positive displacement pumps having full suction but very low discharge.

Causes:

  • Relief valve in open condition due to improper setting of the spring tension.
  • Due to broken spring of the relief valve.

Symptoms:

Discharge pressure gauge shows very low discharge pressure than the normal.

Remedial Actions:

Identify cause & rectify same