3.
MAINTENANCE
IOM manual CTI & CTH centrifugal pumps
16
3.
MAINTENANCE
Maintenance work on electrical installations must be performed by qualified
personnel and only when the power supply has been shutoff. Follow the local
and national safety regulations.
3.1.
Inspections
Periodically check suction and discharge pressures.
Inspect the motor according to the instructions from the motor manufacturer.
In general, a mechanical seal does not require maintenance, but the pump should never
run when empty (dry). If a leakage occurs, replace the mechanical seal.
3.2.
Location of faults
Ov
erhe
at
ing o
f m
ot
or
Ins
uf
fi
ci
ent
f
lo
w
ra
te
o
r
pre
ss
ur
e i
n p
um
p
N
o pr
es
sur
e
on t
he
di
sch
arg
e s
ide
Irre
gul
ar di
sch
arg
e f
lo
w
/
p
re
ss
ur
e
N
oi
se
a
nd
v
ibr
at
io
ns
The
pu
mp g
et
s
cl
ogg
ed
Ov
erhe
at
ing o
f t
he
p
um
p
A
bno
rma
l w
ea
r
Le
ak
in
me
chan
ical
s
ea
l
Possible reason
Solution
X
X
Wrong direction of rotation
Invert the direction of rotation
X X X X
Insufficient suction head (NPSH)
Increase available NPSH:
Raise the suction reservoir
Lower the pump
Increase the pressure in the suction tank
Reduce the vapour pressure
Increase the diameter of the suction pipe
Make suction pipe short and direct
X
Pump is clogged
Clean the pump
X
X X
X Cavitation
Increase suction pressure
X
X X
X The pump sucks air
Make sure all connections are tight
X X X
Suction pipe is blocked
Check pipes / valves and filters on the suction line
X
X
Discharge pressure too high
Reduce the head by increasing pipe diameter and/or
reduce number of valves and bends
X
X X
Flow rate too high
Reduce the flow:
Partially close the discharge valve
Reduce the impeller diameter (contact us)
Reduce the rotation speed
X
X X X X Liquid temperature too high
Cool the liquid
X Broken or worn mechanical seal
Replace the seal
X Wrong material of O-rings for the liquid
Mount O-rings in other material (contact us)
X
X X X
The impeller scratches
Reduce the temperature and / or suction pressure.
Adjust clearance between housing and impeller
X
X Loads on the pipes
Connect the pipes independent of the pump
X X X X Foreign objects in the liquid
Use a filter on the suction side
X Spring tension too low on mechanical seal
Adjust as mentioned in this manual
X
Shut-off valve closed on suction side
Check and open the valve
X
Discharge pressure too low
Increase the pressure – install an impeller with a bigger
diameter (contact us)
X X
Pump is not filled with liquid
Fill pump with liquid
X X
X
Liquid parameters different than calculated
Check pumped liquid parameters
