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
