Flowserve Worthington WXB User Manual download pdf (Page 46)

WXB USER INSTRUCTIONS ENGLISH - 07/14

Page 46 of 51

9.0 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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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

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Pump not primed. Check complete filling

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Pump or suction pipe not completely filled with

liquid.

Check and complete filling

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Suction lift too high or level too low.

Check NPSHa>NPSHr, proper submergence,

losses at strainers / fittings

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Excessive amount of air or gas in liquid. Check and purge from pipes

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Air or vapour pocket in suction line. Check suction line design for pockets

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Air leaks into suction line. Check airtight pipe then joints and gaskets

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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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Foot valve too small. Investigate replacing the foot valve

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Foot valve partially clogged. Clean foot valve

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Inlet of suction pipe insufficiently submerged. Check cut out system design

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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

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Total head of system lower than pump design

head.

Throttle at discharge valve or ask Flowserve if

the impeller can be trimmed

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Specific gravity of liquid different from design. Consult Flowserve

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Viscosity of liquid differs from that for which

designed.

Consult Flowserve

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Operation at very low capacity. Measure value and check minimum permitted

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Operation at high capacity.

Measure value and check maximum

permitted

B. MECHANICAL TROUBLES

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Misalignment due to pipe strain.

Check the flange connections and eliminate

strains using elastic couplings or a method

permitted

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Improperly designed foundation.

Check setting of baseplate: tighten, adjust,

grout base as required

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Shaft bent. Check shaft runouts within acceptable values

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Rotating part rubbing on stationary part

internally.

Check for signs of this and consult Flowserve

if necessary

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Bearings worn Replace bearings

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Wearing ring surfaces worn. Replace worn wear ring/ surfaces

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Impeller damaged or eroded. Replace impeller and check reason

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Leakage under sleeve due to joint failure. Replace joint and check for damage

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Mechanical seal improperly installed.

Check alignment of faces or damaged parts

and assembly method used

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Flowserve Worthington WXB User Manual Page 46

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