Fault Finding Chart; Disposal - Grundfos NB Original Installation And Operating Instructions

15. Fault finding chart

Warning
Before removing the terminal box cover and before any removal/dismantling of the pump, make sure that the power
supply has been switched off. It must be ensured that it cannot be accidentally switched on.
Fault Cause
1. The pump delivers no a) Wrong electrical connection (2 phases).
or too little liquid.
b) Wrong direction of rotation.
c) Air in suction pipe.
d) Counter-pressure too high.
e) Inlet pressure too low.
f)
g) Pump draws in air due to defective seal.
h) Pump draws in air due to low liquid level.
2. The motor-protective a) Pump blocked by impurities.
circuit breaker has
b) Pump running above the rated duty point.
tripped because the
c) Density or viscosity of the liquid is higher than
motor is overloaded.
d) Motor-protective circuit breaker overload
e) The motor runs on 2 phases.
3. Pump makes too a) Inlet pressure too low (cavitation).
much noise.
Pump runs unevenly
and vibrates.
b) Air in suction pipe or pump.
c) Counter-pressure is lower than specified.
d) Pump draws in air due to low liquid level.
e) Impeller out of balance (clogged impeller
f)
g) Pump stressed by the pipework (thus causing
h) Defective bearings.
i)
j)
k) Frequency converter operation.
4. Leakage in pump or at a) Pump stressed by the pipework (thus causing
connections.
Leakage in
b) Pump housing gaskets and gaskets at
mechanical shaft seal.
c) Mechanical shaft seal dirty or stuck together. Check and clean the mechanical shaft seal.
d) Mechanical shaft seal defective.
e) Shaft surface defective.
5. Too high temperature a) Air in suction pipe or pump.
in pump or motor.
b) Inlet pressure too low.
c) Bearings lubricated with too little, too much or
d) The axial pressure is too high.
e) Motor-protective circuit breaker is defective or
f)

16. Disposal

This product or parts of it must be disposed of in an
environmentally sound way:
1. Use the public or private waste collection service.
26
Suction pipe or impeller blocked by impurities. Clean the pump.
specified when ordering.
setting is incorrect.
blades).
Inner parts worn.
starting noise).
Defective motor fan.
Foreign bodies in the pump.
leaks in the pump or at connections).
connections defective.
unsuitable lubricant.
setting is incorrect.
The motor is overloaded.
Remedy
Check the electrical connection and remedy, if necessary.
Interchange two phases of the power supply.
Vent the suction pipe or the pump and replenish.
Set the duty point in accordance with the data sheet.
Check the system for impurities.
Increase the liquid level on the suction side. Open the
isolating valve in the suction pipe. Make sure that all the
conditions in 7.6 Pipework are complied with.
Check the pipeline seals, pump housing gaskets and
shaft seals, and replace, if necessary.
Increase the liquid level on the suction side and keep it
as constant as possible.
Clean the pump.
Set the duty point in accordance with the data sheet.
If less flow is sufficient, reduce the flow on the discharge
side. Or fit a more powerful motor.
Check the setting of the motor-protective circuit breaker
and replace, if necessary.
Check the electrical connection. Replace the fuse, if
defective.
Increase the liquid level on the suction side. Open the
isolating valve in the suction pipe. Make sure that all the
conditions in 7.6 Pipework are complied with.
Vent the suction pipe or the pump and replenish.
Set the duty point in accordance with the data sheet.
Increase the liquid level on the suction side and keep it
as constant as possible.
Clean and check the impeller.
Replace defective parts.
Mount the pump so that it is not stressed.
Support the pipes.
Replace the bearings.
Replace the fan.
Clean the pump.
See 9.2 Frequency converter operation.
Mount the pump so that it is not stressed.
Support the pipes.
Replace pump housing gaskets or gaskets at
connections.
Replace the mechanical shaft seal.
Replace the shaft.
Vent the suction pipe or the pump and replenish.
Increase the liquid level on the suction side. Open the
isolating valve in the suction pipe. Make sure that all the
conditions in 7.6 Pipework are complied with.
Replenish, reduce or replace lubricant.
Check the relief holes of the impeller and the lock rings
on the suction side.
Check the setting of the motor-protective circuit breaker
and replace, if necessary.
Reduce the flow rate.
2. If this is not possible, contact the nearest Grundfos company
or service workshop.
Subject to alterations.