10. Fault finding the product
Fault
Cause
Remedy
The outlet pressure is too low.
The speed of rotation is too low.
Reestablish the correct speed and direction
of rotation.
The system pressure is lower than
anticipated.
Check the system curve.
There is air or gas in the pumped liquid.
Remove the air from the pumped liquid.
The wear rings are worn.
Replace the wear rings.
The impeller is damaged.
Repair or replace the impeller.
The impeller diameter is too small.
Replace the impeller with one of the correct
diameter.
The direction of rotation is wrong.
Interchange two wires in the power supply.
The pump has lost its prime.
Re-prime the pump.
There is insufficient NPSH.
Restore required NPSH.
Passages are restricted.
Clean the impeller and pump housing
passages.
Joints or the stuffing box are leaking.
•
Tighten the joints or the stuffing box
gland.
•
Replace the shaft sleeve.
•
Replace the gaskets.
The inlet pressure is insufficient.
The inlet line is drawing air.
Tighten the connections.
The suction lift is too high, or there is
insufficient NPSH.
Reduce the suction lift or restore the required
NPSH.
Air or gas is trapped in the pumped liquid.
Remove the trapped air or gas from liquid.
The strainer is clogged.
Clean the strainer.
The noise level has increased.
Poor alignment of the pump. The inlet and
outlet pipe clamps are loose.
•
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.
The foundation is cracked.
Repair the foundation.
The ball bearings are worn.
Replace the worn bearings, and renew the
lubrication.
The motor is unbalanced.
•
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.
Hydraulic resonance.
•
Alter the resonant pipes.
•
Change the pump speed.
•
Insert a pulsation damper on the pump
or the pipes.
•
Insert a flow straightener.
Insufficient flow.
The pump is not primed.
Prime the pump.
The system pressure exceeds the shut-off
pressure.
•
Increase the liquid level on the inlet side.
•
Open the isolating valve in the inlet pipe.
The speed of rotation is too low.
Reestablish the correct speed of rotation.
The suction lift is too high, or there is
insufficient NPSH.
Reduce the suction lift or restore the required
NPSH.
The strainer or the impeller is clogged.
Clean the strainer and the impeller passages.
Wrong direction of rotation.
Reestablish the correct direction of rotation.
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English (US)
