Sempomp TKF-K Series - Troubleshooting Guide - Part 1; Liquid, Air, and Cavitation Issues; Suction Depth, Discharge Height, and Speed; Rotation Direction and Impeller Clogging

1
There is air in liquid
Swirls occur since depth of submersion pipe is
not enough and there fore air is not absorbed.
Control the liquid level in suction tank and
increase the depth of bottom/suction pipe back
liquid valve.
2
Air pocket in suction pipe
Control the slope of suction pipe and whether
there are suitable places for formation of air
pockets, if any make necessary corrections.
3
There may be air in pump
and/or suction line
Fill pump or suction pipe completely with liquid
and repeat the start process
4
Air is be absorbed from seal,
suction pipe, or connections.
Pump absorbs liquid which is
mixed with air
Control all connections in suction pipe. Check
seals. If necessary feed seals with pressurized
liquid. Check the submersion depth of suction
pipe pr deep back liquid valve and increase
submersion depth if necessary.
5
Pump operates with
cavitations
NPSH of plant is very low. Check the liquid level
in suction tank. Check whether there are over
friction losses in suction line. Check whether
isolation valve in suction line is completely open.
If necessary place the pump in low levels and
increase the load of pump at suction side
6
Suction depth is very much
If there is no obstacle which may cause clogging
control the friction losses of suction line. If
necessary use a suction pipe having larger
diameter. If static suction depth is too much you
should raise the height of liquid level in suction
tank or pump should be places in lower levels.
7
Increase in discharge height
Check whether valves are completely open. Check
whether there is an obstacle which may cause
clogging in discharge pipe.
8
Pumps discharge height is
insufficient
Actual discharge height of plant is higher than given
values. Check the total static height and friction
losses of discharge pipe. Using pipes having
greater diameter may be solution. Check whether
valves are completely opened.
9
Pump is operating at lower
discharge height
Discharge height of plant is lower than given
values. Lathe the impellor diameter according to
manufacturer suggestions
10
Speed very much
Decrease the motor revolution if possible or Lathe
the impellor diameter according to manufacturer
suggestions
11
Speed very low
Check the voltage and frequency of line and check
whether phase is missing in motor.
12
Pump rotates reverse
Check rotation direction of motor whether it is
same with the direction which is indicated in pump
body or nameplate
13
ImpellEr partially clogged
Clean the impellor