Flowserve L Worthington Simpson - Manual (Page 28)

L and U USER INSTRUCTIONS ENGLISH 85392721 07-12
Page 28 of 36 flowserve.com
7 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
P u m p o v e r h e a t s a n d s e i z e s
⇓ ⇓ ⇓ ⇓ B e a r i n g s h a v e s h o r t l i f e
⇓ ⇓ ⇓ ⇓ P u m p v i b r a t e s o r i s n o i s y
⇓ ⇓ ⇓ ⇓ M e c h a n i c a l s e a l h a s s h o r t l i f e
⇓ ⇓ ⇓ ⇓ M e c h a n i c a l s e a l l e a k s e x c e s s i v e l y
⇓ ⇓ ⇓ ⇓ P u m p r e q u i r e s e x c e s s i v e p o w e r
⇓ ⇓ ⇓ ⇓ P u m p l o s e s p r i m e a f t e r s t a r t i n g
⇓ ⇓ ⇓ ⇓ I n s u f f i c i e n t p r e s s u r e d e v e l o p e d
⇓ ⇓ ⇓ ⇓ I n s u f f i c i e n t c a p a c i t y d e l i v e r e d
⇓ ⇓ ⇓ ⇓ P u m p d o e s n o t d e l i v e r l i q u i d
⇓ ⇓ ⇓ ⇓
POSSIBLE 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 NPSH
A
>NPSH
R
, 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 run outs 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.