Grundfos CMB Manual Del Usuario página 8

Fault
8. The pump
performance is
unstable.
9. The pump runs
backwards when
switched off.
Self-priming pumps only:
10. The pump
performance is
unstable and the
pump is noisy.
11. When startup is
attempted, the
pump will start, but
delivers no
pressure or flow.
12. The pump runs, but
does not deliver
the rated flow.
13. The pump
performance is
unstable.
14. The pump runs
backwards when
switched off.
Self-priming pumps only:
15. The pump
performance is
unstable and the
pump is noisy.
16. When startup is
attempted, the
pump will start, but
delivers no
pressure or flow.
8
Cause
a) Pump inlet pressure too low.
b) Suction pipe is partly blocked by
impurities.
c) Leakage in suction pipe.
d) Air in suction pipe or pump.
a) Leakage in suction pipe.
b) Foot or non-return valve defective.
c) The foot valve is stuck in completely
or partly open position.
a) The differential pressure across the
pump is too low.
a) Liquid column above non-return
valve in discharge pipe prevents the
pump from self-priming.
b) Suction pipe draws in air.
a) The internal valve did not close.
a) Pump inlet pressure too low.
b) Suction pipe is partly blocked by
impurities.
c) Leakage in suction pipe.
d) Air in suction pipe or pump.
a) Leakage in suction pipe.
b) Foot or non-return valve defective.
c) The foot valve is stuck in completely
or partly open position.
a) The differential pressure across the
pump is too low.
a) Liquid column above non-return
valve in discharge pipe prevents the
pump from self-priming.
b) Suction pipe draws in air.
Remedy
Check the inlet conditions of the pump.
Remove and clean the suction pipe.
Remove and repair the suction pipe.
Vent the suction pipe/pump.
Check the inlet conditions of the pump.
Remove and repair the suction pipe.
Remove and clean, repair or replace
the valve.
Remove and clean, repair or replace
the valve.
Close the tap gradually until the
discharge pressure is stable and the
noise has ceased.
Empty the discharge pipe. Make sure
that the non-return valve does not hold
back liquid in the discharge pipe.
Repeat the startup procedure.
Make sure that the suction pipe is
airtight from pump to liquid level.
Repeat the startup procedure.
Close the tap gradually until the
pressure or flow suddenly increases.
Then open the tap gradually until the
required flow is reached.
Check the inlet conditions of the pump.
Remove and clean the suction pipe.
Remove and repair the suction pipe.
Vent the suction pipe/pump.
Check the inlet conditions of the pump.
Remove and repair the suction pipe.
Remove and clean, repair or replace
the valve.
Remove and clean, repair or replace
the valve.
Close the tap gradually until the
discharge pressure is stable and the
noise has ceased.
Empty the discharge pipe. Make sure
that the non-return valve does not hold
back liquid in the discharge pipe.
Repeat the startup procedure.
Make sure that the suction pipe is
airtight from pump to liquid level.
Repeat the startup procedure.