3
Installation, Operation & Maintenance CM MAG-P series Manual ENG 2012 ISM0059 REV 01
TROUBLE
POSSIBLE CAUSE
INVESTIGATIVE/CORRECTIVE
ACTION
No flow, no pressure at
start up.
Pump not completely filled with liquid.
Check the suction conditions as the pump must be full-
filled.
Allow more cool down time if pumping low temperature
fluid.
Check suction line for air leak if suction pressure is
lower than atmospheric.
NPSH actually lower that NPSH requirement
listed on specification sheet.
Suction line blocked
– check suction screen and valve.
Excessive pressure drop through suction piping.
Flow restricted by vapour pockets in high points of
suction line.
Suction tank level or pressure too low.
Entrained air or vapour in pumped fluid.
NPSH reduced by presence of more volatile fluid in
process fluid.
Failure of drive component, such as
interconnecting shaft.
Disassemble and inspect.
Reverse direction of rotation.
Note: impeller and driver rotate in the same direction.
Insufficient flow or
head-rise.
NPSH actually lower than NPSH requirement.
Refer to solutions listed under “No flow, no pressure at
start-
up”.
Diffuser discharge partially plugged or impeller
damaged by passage of a solid particle.
Clean these areas of all obstructions and restore
surfaces to a smooth polished finish (use emery cloth or
machine), free of all corrosion pitting.
Drive speed too low.
Check speed against value listed on specification sheet.
Driven overloaded.
Pressure gauges of flow meters in error.
Calibrate instrumentation.
Fluid specific gravity or viscosity higher than
values listed on specification sheet.
Check actual viscosity and specific gravity against value
listed on specification sheet.
Electrical failure in electric driver.
Check circuit breaker heater size and setting.
Check voltage.
Current for each phase should be balanced within three
percent.
Mechanical failure in driver, or pump.
Remove driver and check for freedom of rotation of
pump shaft assemblies.
Remove fluid end and search for any mechanical failure.
Insufficient NPSH.
Refer to solution for insufficient NPSH under “No flow,
no pressure at start-
up”, above.
Excessive discharge
pressure pulsations.
