Flowserve ERPN-M User Instructions page 32

8.0 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
Pump overheats and seizes
⇓ Bearings have short life
⇓
⇓ Pump vibrates or is noisy ⇓
⇓ Magnetic coupling has short life
⇓
⇓ Magnetic coupling leaks excessively
⇓
⇓ Pump requires excessive power ⇓
⇓ Pump loses prime after starting
⇓
⇓ Insufficient pressure developed
⇓
⇓ Insufficient capacity delivered ⇓
⇓ Pump does not deliver liquid
⇓
⇓ PROBABLE CAUSES ⇓
A. SYSTEM TROUBLES
Pump not primed.
Pump or suction pipe not completely filled with
liquid.
Suction lift too high or level too low.
Excessive amount of air or gas in liquid.
Air or vapour pocket in suction line.
Air leaks into suction line.
Air leaks into pump through mechanical seal,
sleeve joints, casing joint or pipe lugs.
Foot valve too small.
Foot valve partially clogged.
Inlet of suction pipe insufficiently submerged.
Total head of system higher than differential
head of pump.
Total head of system lower than pump design
head.
Specific gravity of liquid different from design.
Viscosity of liquid differs from that for which
designed.
Operation at very low capacity.
Operation at high capacity.
B. MECHANICAL TROUBLES
Misalignment due to pipe strain.
Improperly designed foundation.
Shaft bent.
Rotating part rubbing on stationary part
internally.
Bearings worn
Wearing ring surfaces worn.
Impeller damaged or eroded.
Leakage under sleeve due to joint failure.
Magnetic coupling improperly installed.
ERPN-M USER INSTRUCTIONS ENGLISH 02-08
POSSIBLE REMEDIES
Check complete filling
Check and complete filling
Check NPSHa>NPSHr, proper submergence,
losses at strainers / fittings
Check and purge from pipes
Check suction line design for pockets
Check airtight pipe then joints and gaskets
Check airtight assembly then joints and
gaskets
Investigate replacing the foot valve
Clean foot valve
Check cut out system design
Check discharge head and head losses in
discharge pipe at the valve settings. Check
back pressure is not too high
Throttle at discharge valve or ask Flowserve if
the impeller can be trimmed
Consult Flowserve
Consult Flowserve
Measure value and check minimum permitted
Measure value and check maximum
permitted
Check the flange connections and eliminate
strains using elastic couplings or a method
permitted
Check setting of baseplate: tighten, adjust,
grout base as required
Check shaft runouts within acceptable values
Check for signs of this and consult Flowserve
if necessary
Replace bearings
Replace worn wear ring/ surfaces
Replace impeller and check reason
Replace joint and check for damage
Check alignment of faces or damaged parts
and assembly method used
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