Flowserve Worthington WXB - Manual (Page 46)

WXB USER INSTRUCTIONS ENGLISH - 07/14
Page 46 of 51
9.0 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 / 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 that for which
designed.
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
Rotating part rubbing on stationary part
internally.
Check for signs of this and consult Flowserve
if necessary
Bearings worn Replace bearings
Wearing ring surfaces worn. Replace worn wear ring/ surfaces
Impeller damaged or eroded. Replace impeller and check reason
Leakage under sleeve due to joint failure. Replace joint and check for damage
Mechanical seal improperly installed.
Check alignment of faces or damaged parts
and assembly method used