NMFIRE NFPA20 - 6.1 Electric motor pump

－54－
Trouble
Possible causes
Remedy
4. The motor starter starts
normally, but the pump does
not run
e) The main contactor of the
motor starter is not
connected or the
electromagnetic coil is
discontinuous.
Replace the contactor or
electromagnetic coil.
5. Pump flow uneven
a) Pump suction pressure is
too low (NPSH).
Check the pump suction
port.
b) Suction pipe/pump have
been blocked.
Clean the pump or suction
pipe.
c) Air enter into pump.
Check the pump suction
condition.
6. Pump runs but no water
out
a) Suction pipe/pump have
been blocked.
Clean the pump or suction
pipe.
b) Suction pipe/pump have
been blocked.
Repair bottom valve or
check valve.
c) Suction pipe leaks.
Repair suction pipe.
d) Suction pipe or pump
enter into air.
Check the pump suction
condition.
e) Motor rotate direction is
not correct.
Change the motor rotation
direction.
7. When the switch is off, the
pump turns in the opposite
direction
a) Suction pipe leaks.
Repair suction pipe.
b) Bottom valve or check
valve failed.
Repair bottom valve or
check valve.
8. Shaft seal leaks
Shaft seal failed.
Replace shaft seal.
9. Loud nosie
a) Pump cavitation.
Check operation mode and
improve inlet runner
condition.
b) Due to the incorrect
installation position of the
shaft, the pump rotation is
not normal flexibility.
(subject to friction
resistance).
Adjust pump shaft.