34
KM70
ENG_DEBEM S.r.l.
Rev. 01A-EN
01/03/2021
9. Malfunctions and solutions
Prior to performing any operation on the pump disconnect the power.
Do not, in any case, operate on pumps or components that have not been fully
purged.
In compliance with regulation 81/08, our technical assistance service cannot
operate on pumps or components which have not been fully purged. Therefore
we will be forced to return to sender all pumps we receive that have not been
purged.
9.1 Malfunction table: possible causes and solutions
A
The pump delivers an insufficient flow rate
B
Motor overloading/overheating
C
Excessive increase of the bearing temperature (where present)
D
Leaks from the pump, the mechanical seal (when present) or connections
E
Vibrations during pump operation
F
Excessive increase of the temperature inside the pump
A
B
C
D
E
F
Possible cause
Solution
X
The pump is not primed correctly
Prime the pump and bleed any air
in the pipes/volute casing.
X
High head loss.
Set the operation point in accord-
ance with the pump characteristic
curves. Check that the pumped
liquid is free from impurities.
Check the diameter of the impel-
ler; it may be too small
X
X
X
Air in the pump or pumped liquid.
The pump or piping are not fully
bled/filled
Check the piping seal and the
gaskets of the volute casing; re-
place them if necessary. Bleed
and/or fill up
X
Intake manifold or impeller
clogged and/or blocked
Remove any sediment from the
pump or piping
X
X
X
Available NPSH too low (cavita-
tion)
Check/increase the suction head.
Open the suction cut-off valve.
Check suction head loss. Check
and clean any filter installed on
suction
X
Wrong direction of rotation
Invert the two power supply
phases of the motor (in case of
three-phase power supply)
X
Speed is too low, wrong electrical
connections (a phase is missing)
Check the electrical connections
and correct them if necessary.
Check and increase voltage/fre-
quency within the allowed range
if necessary
X
Power voltage too low
Check electrical installation
