15
Pump Typ Z
Version: 27215 -G.1
Schmalenberger GmbH + Co. KG
D-72072 Tübingen / Germany
4.5
Fault Elimination
Table 1: The causes and elimination of faults
P
u
mp st
ands still
too li
ttl
e
deli
ver
y
rate from
pump
mo
to
r overload
too
low p
u
mp p
ressure
too
h
igh
pu
mp p
ressure
h
ig
h
motor / bearing temp
eratu
re
p
u
mp leaks
p
u
mp ru
ns noisily
, ru
nning noises
p
u
mp temp
era
tu
re too high
Cause of the fault
Elimination of the fault
x
x
Back pressure too high, pump is deli-
vering against too high a pressure,
system resistance too great, pipe too
small
Set new operating point, system dirty,
increase rotation speed, install a new
impeller, clean pipes, increase pipe
size, install larger pump
x
x
x
Pump / pipework not completely ven-
ted, air suction through too small a
covering, gas build-up, air bubble in
the pipework, high percentage of air in
the medium, supply or impeller bloc-
ked.
Increase fluid level, correct level con-
trol, install pump lower down, vent the
system, clean pipework, change pipe-
work, de-gas the medium, decrease
resistance in the supply pipe, fully
open valves in the suction pipe, clean
sieves and suction connections, install
a relief valve directly in front of the
non-return valve.
x
x
Wrong phase sequence, wrong electri-
cal connections, rotation speed to low,
gap between wearing plate and open
impeller too large, air entering via the
throttling section
Change over two of the phases in the
terminal box, increase rotation speed
(*) (if necessary, get new motor),
decrease the gap between wearing
plate and open impeller, renew thrott-
ling section, install pump lower down
or increase fluid level
x
x
Worn internal parts (e.g. impeller)
Remove foreign body from pump
housing, replace worn parts, renew
throttling section
x
x
Pump back pressure is lower than sta-
ted in the specifications, electrical
connections wrong
Set operating point precisely, increase
back pressure e.g.: by throttling the
pump on the pressure side, perhaps
turn off impeller (*), larger motor (*),
compare electrical connections with
those on the motor rating plate;
observe circuit diagram in chapter
3.3.4
x
x
Higher density or greater viscosity of
the delivery medium than in the speci-
fications
New pump correlation (*)
x
Cavitation
Throttle pump on pressure side, larger
pump (*)
x
System resistances too low, manome-
ter defective
Increase back pressure, e.g. by thrott-
ling the pump on the pressure side,
larger pump (*), larger impeller (*)
