Fault Finding The Product - Grundfos KP Notice D'installation Et De Fonctionnement

9. Fault finding the product

DANGER
Electric shock
Death or serious personal injury.
- Before starting any work on the product, make
sure that the power supply has been switched off
and that it cannot be accidentally switched on.
CAUTION
Toxic material
Minor or moderate personal injury.
- Wash down the pump before doing any work on it.
Fault
1. The outlet pressure is too low.
2. The inlet pressure is insufficient.
3. The noise level has increased.
Cause
a) The speed of rotation is too low.
b) The system pressure is lower than
anticipated.
c) There is air or gas in the pumped liquid.
d) The wear rings are worn.
e) The impeller is damaged.
f) The impeller diameter is too small.
g) The direction of rotation is wrong.
h) The pump has lost its prime.
i) There is insufficient NPSH.
j) Passages are restricted.
k) Joints or the stuffing box are leaking.
a) The inlet line is drawing air.
b) The suction lift is too high or there is
insufficient NPSH.
c) Air or gas is trapped in the pumped liquid.
d) The strainer is clogged.
a) Poor alignment of the pump.
The inlet and outlet pipe clamps are loose.
b) Cracked foundation.
c) Worn ball bearings.
d) The motor is unbalanced.
e) Hydraulic resonance.
DANGER
Hot, caustic, flammable or toxic materials,
including vapors
Death or serious personal injury.
- Be extremely cautious when venting and/or
draining hazardous liquids.
Wear protective clothing when there are caustic,
corrosive, volatile, flammable, or hot liquids.
Do not breathe toxic vapors.
Do not allow sparks, open fire, or hot surfaces
near the equipment.
Remedy
Reestablish the correct speed and direction of
rotation.
Check the system curve.
Remove the air from the pumped liquid.
Replace the wear rings.
Repair or replace the impeller.
Replace the impeller with one of the correct
diameter.
Interchange two wires in the power supply.
Re-prime the pump.
Restore required NPSH.
Clean the impeller and pump housing
passages.
• Tighten the joints or the stuffing box gland.
• Replace the shaft sleeve.
• Replace the gaskets.
Tighten the connections.
Reduce the suction lift or restore required
NPSH.
Remove the trapped air or gas from liquid.
Clean the strainer.
• Reestablish proper alignment of the pump
and the motor.
• Support the inlet and outlet pipes.
• Make sure the vibration dampers, flexible
pipes and conduit connectors are installed
correctly.
Repair the foundation.
• Replace the worn bearings.
• Renew the lubrication.
• Disconnect the motor and operate it alone.
• Remove large pieces of debris, such as
wood or rags from the pump.
• Clean out the pump, if necessary.
• Alter the resonant pipes.
• Change the pump speed.
• Insert a pulsation damper on the pump or the
pipes.
• Insert a flow straightener.
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