7 faults; causes and remedies – Flowserve MPT User Manual

Page 25

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MPT USER INSTRUCTIONS ENGLISH 85392699 06-09

25 of 41

®

7 FAULTS; CAUSES AND REMEDIES

FAULT SYMPTOM

Pump overheats and seizes

Bearings have short life

Pump vibrates or is noisy

Mechanical seal has short life

Mechanical seal leaks excessively

Pump requires excessive power

Pump loses prime after starting

Insufficient pressure developed

Insufficient capacity delivered

Pump does not deliver liquid

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

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