P
ump
deliv
er
s
ins
uf
fic
ient
flow
rat
e
Mot
or
is
ov
er
loaded
E
xc
es
siv
e
cur
rent
cons
umpt
ion
E
xc
es
siv
e
pow
er
cons
umpt
ion
Leak
age
at
the
pump
V
ibr
at
ions
dur
ing
pump
oper
at
ion
E
xc
es
siv
e
ris
e
of
temper
at
ur
e
ins
ide
the
pump
G
rinding
nois
e
P
ump
is
running,
but
does
not
deliv
er
Secochem-Ex
22
8
Trouble-shooting
Cause
Remedy
1)
*
Pump delivers against an excessively high discharge
pressure.
Re-adjust to duty point by opening the shut-off valves ac-
cordingly.
*
Excessively high back pressure.
Check plant for impurities.
Fit a larger impeller.
2)
*
* *
Pump or piping are not completely vented or primed.
Vent and/or prime.
*
Supply line or impeller clogged.
Remove deposits in the pump and/or piping.
*
Formation of air pockets in the piping.
Alter piping layout.
Fit a vent valve.
*
* *
NPSH
available
(positive suction head) is too low.
Check/alter liquid level.
Fully open 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.
*
Suction lift is too high.
Clean suction strainer and suction lines.
Check/alter liquid level.
Change suction line.
* *
Wrong direction of rotation.
Interchange two of the phases of the power supply cable.
*
Speed is too low
2)
-- in frequency inverter operation.
-- not in frequency inverter operation.
-- On frequency inverter, increase voltage/frequency
within the permissible range.
-- Check voltage.
* * * *
*
Wear of internal pump parts.
Replace worn components by new ones.
*
Pump back pressure is lower than specified in the pur-
chase order.
Adjust duty point accurately.
In the case of persistent overloading, turn down impeller.
2)
*
Density or viscosity of the fluid pumped is higher than
stated in the purchase order.
2)
* *
Operating voltage is too low.
Increase voltage; check fall in voltage in the connection
line
* * * *
Motor is running on two phases only.
Replace the defective fuse.
Check the electric cable connections.
*
Connection bolts have loosened.
Tighten the bolts.
Fit new sealing elements.
*
Rotor is out of balance.
Clean the impeller.
Re-balance the impeller.
* *
*
*
Defective bearing(s).
Fit new bearings.
*
Insufficient rate of flow.
Increase the minimum rate of flow.
*
Motor is not running because of lack of voltage.
Check electrical connections.
*
Rotor blocked due to corrosion or oxidation.
(Risk of dry-running)
2)
*
*
Motor winding or electric cable are defective.
2)
*
Excessive temperature
Product temperature is too high.
* *
Incorrect operating data:
Flow rate is too high.
Viscosity is too high.
*
Impeller or rotor rub on the pump casing.
Clean impeller or rotor.
*
*
Bores for cooling / lubricating flow are clogged.
Clean.
1) Pump pressure must be released before attempting to remedy faults on parts which are subjected to pressure.
2) Request particulars.
