ERPN-M USER INSTRUCTIONS ENGLISH 02-08
Page 32 of 37
8.0 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
Pump overheats and seizes
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Bearings have short life
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Pump vibrates or is noisy
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Magnetic coupling has short life
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Magnetic coupling leaks excessively
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Pump requires excessive power
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Pump loses prime after starting
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Insufficient pressure developed
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Insufficient capacity delivered
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Pump does not deliver liquid
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PROBABLE CAUSES
POSSIBLE REMEDIES
A. SYSTEM TROUBLES
z
z
Pump not primed.
Check complete filling
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z
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z
Pump or suction pipe not completely filled with
liquid.
Check and complete filling
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z
z
z
z
Suction lift too high or level too low.
Check NPSHa>NPSHr, proper submergence,
losses at strainers / fittings
z
z
z
Excessive amount of air or gas in liquid.
Check and purge from pipes
z
z
z
Air or vapour pocket in suction line.
Check suction line design for pockets
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z
Air leaks into suction line.
Check airtight pipe then joints and gaskets
z
z
Air leaks into pump through mechanical seal,
sleeve joints, casing joint or pipe lugs.
Check airtight assembly then joints and
gaskets
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z
Foot valve too small.
Investigate replacing the foot valve
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Foot valve partially clogged.
Clean foot valve
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z
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Inlet of suction pipe insufficiently submerged.
Check cut out system design
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z
z
Total head of system higher than differential
head of pump.
Check discharge head and head losses in
discharge pipe at the valve settings. Check
back pressure is not too high
z
Total head of system lower than pump design
head.
Throttle at discharge valve or ask Flowserve if
the impeller can be trimmed
z
Specific gravity of liquid different from design.
Consult Flowserve
z
z
z
Viscosity of liquid differs from that for which
designed.
Consult Flowserve
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z
Operation at very low capacity.
Measure value and check minimum permitted
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z
z
Operation at high capacity.
Measure value and check maximum
permitted
B. MECHANICAL TROUBLES
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z
z
z
z
z
Misalignment due to pipe strain.
Check the flange connections and eliminate
strains using elastic couplings or a method
permitted
z
Improperly designed foundation.
Check setting of baseplate: tighten, adjust,
grout base as required
z
z
z
z
z
Shaft bent.
Check shaft runouts within acceptable values
z
z
z
z
Rotating part rubbing on stationary part
internally.
Check for signs of this and consult Flowserve
if necessary
z
z
z
z
z
Bearings worn
Replace bearings
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z
z
Wearing ring surfaces worn.
Replace worn wear ring/ surfaces
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z
z
Impeller damaged or eroded.
Replace impeller and check reason
z
Leakage under sleeve due to joint failure.
Replace joint and check for damage
z
z
z
Magnetic coupling improperly installed.
Check alignment of faces or damaged parts
and assembly method used
