Grundfos CM 1 Manual De Instrucciones página 19

Fault
6. The pump performance is
unstable and the pump is
noisy.
7. The pump runs, but gives
no water.
8. When start-up is attempted,
the pump will start, but
delivers no pressure or flow.
9. The pump runs, but does
not deliver the rated flow.
10. The pump runs backwards
when switched off.
11. The pump runs with
reduced performance.
Cause
Self-priming pumps only:
a) The differential pressure
across the pump is too low.
a) Pump inlet pressure too low.
b) The suction pipe is partly
clogged by impurities.
c) The foot or non-return valve is
stuck in its closed position.
d) Leakage in suction pipe.
e) Air in suction pipe or pump.
Self-priming pumps only:
a) Liquid column above
non-return valve in discharge
pipe prevents the pump from
self-priming.
b) Suction pipe draws in air.
Self-priming pumps only:
a) The internal valve did not
close.
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) Wrong direction of rotation.
b) See 5. a), b), c), d).
Remedy
Close the tap gradually until the
discharge pressure is stable and the
noise has ceased.
See 5. a).
See 5. b).
Remove and clean, repair or replace
the valve.
See 5. c).
See 5. d).
Empty the discharge pipe. Make
sure that the non-return valve does
not hold back liquid in the discharge
pipe. Repeat the start-up procedure
in section 6.2.2.
Make sure that the suction pipe is
airtight from pump to liquid level.
Repeat the start-up procedure in
section 6.2.2.
Close the tap gradually until a
sudden rise in pressure or flow can
be seen. Then open the tap
gradually until the required flow is
reached.
See 5. c).
See 6. c).
See 6. c).
Three-phase pumps only:
Switch off the power supply with the
external circuit breaker, and
interchange two phases in the pump
terminal box. See also section
8.3 Checking the direction of
rotation.
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