Fault Finding - Grundfos LFE Instrucciones De Instalación Y Funcionamiento

10. Fault finding

DANGER
Electric shock
Death or serious personal injury
- Before starting any work on the product, be sure
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. Outlet pressure is too low.
2. Insufficient inlet pressure.
3. Noise level has increased.
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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) Wrong direction of rotation.
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.
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 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/gas from liquid.
Clean the strainer.
• Ensure 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.