7 faults; causes and remedies – Flowserve MPT User Manual
Page 25
MPT USER INSTRUCTIONS ENGLISH 85392699 06-09
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7 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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Mechanical seal has short life
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Mechanical seal 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
Pump not primed.
Check complete filling
Pump or suction pipe not completely filled
with liquid.
Check and complete filling
Suction lift too high or level too low.
Check NPSHa>NPSHr, proper
submergence, losses at strainers and
fittings
Excessive amount of air or gas in liquid.
Check and purge from pipes
Air or vapour pocket in suction line.
Check suction line design for pockets
Air leaks into suction line.
Check airtight pipe then joints and
gaskets
Air leaks into pump through mechanical seal,
sleeve joints, casing joint or pipe lugs.
Check airtight assembly then joints
and gaskets
Foot valve too small.
Investigate replacing the foot valve
Foot valve partially clogged.
Clean foot valve
Inlet of suction pipe insufficiently submerged. Check cut out system design
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
Total head of system lower than pump design
head.
Throttle at discharge valve or ask
Flowserve if the impeller can be
trimmed
Specific gravity of liquid different from design. Consult Flowserve
Viscosity of liquid differs from design.
Consult Flowserve
Operation at very low capacity.
Measure value and check minimum
permitted
Operation at high capacity.
Measure value and check maximum
permitted
B. MECHANICAL TROUBLES
Misalignment due to pipe strain.
Check the flange connections and
eliminate strains using elastic
couplings or a method permitted
Improperly designed foundation.
Check setting of baseplate: tighten,
adjust, grout base as required
Shaft bent.
Check shaft runouts within acceptable
values