8 Trouble-shooting
Pump delivers insufficient flow rate
Motor overload
Excessive pump discharge pressure
Excessive bearing temperature
Leakage at the pump
Excessive leakage at the shaft seal
Vibrations during pump operation
Excessive rise of temperature inside the pump
Table 27: Trouble-shooting
A B C D E F G H Possible cause
Remedy
22)
X Pump delivers against an excessively
high discharge pressure.
Re-adjust to duty point.
x Excessively high back pressure. Check plant for impurities.
Fit a larger impeller.
23)
Increase the speed (turbine, I.C. engine).
X X X Pump or piping are not completely
vented or primed.
Vent and/or prime.
X Supply line or impeller clogged. Remove deposits in the pump and/or piping.
X Formation of air pockets in the piping. Modify the piping.
Fit a vent valve.
X X X Pump is warped or sympathetic
vibrations in the piping.
Check pipeline connections and secure fixing
of pump; if required, reduce the distances
between the pipe clamps.
Fix the pipelines using anti-vibration material.
X X X Suction head is too high,
NPSH
available
(positive suction head) is too
low.
Check/alter liquid level.
Fully open the shut-off valve in the suction
line.
Change suction line if the friction losses in the
suction line are too high.
Check any strainers installed/suction opening.
Observe permissible speed of pressure fall.
X
Increased axial thrust.
23)
Correct rotor adjustment.
X Air intake at the shaft seal. Fit new shaft seal.
X Wrong direction of rotation. Interchange two of the phases of the power
supply cable.
X X Motor is running on two phases only. Replace the defective fuse.
Check the electric cable connections.
X Speed is too low.
- Pump operation with frequency
inverter
- Pump operation without frequency
inverter
- Increase voltage/frequency at the frequency
inverter in the permissible range.
- Check the voltage.
X Defective bearing(s) Fit new bearing(s).
X X X Flow rate is too low. Increase the minimum flow rate.
X X Wear of internal pump parts Replace worn components by new ones.
X Density or viscosity of the fluid pumped
is higher than stated in the purchase
order.
Contact KSB.
X Use of unsuitable materials. Change the material combination.
X X Speed is too high.
Reduce speed.
23)
A
B
C
D
E
F
G
H
22)
Pump pressure must be released before attempting to remedy faults on parts which are subjected to pressure.
23)
Contact KSB.
8 Trouble-shooting
KWP
69 of 78
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