Flowserve CPXS - Manual (Page 32)

CPXS, CPXNS and CPXPS USER INSTRUCTIONS ENGLISH 71569250 07-11
Page 32 of 48 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
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 ft 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.
Pump or suction pipe not completely filled with
liquid.
Check complete filling. Vent and/or prime.
Suction lift too high or level too low.
Insufficient margin between suction pressure and
vapour pressure.
Check NPSH
A
> NPSH
R
, proper submergence,
losses at strainers and fittings.
Excessive amount of air or gas in liquid. Check and purge pipes and system.
Air or vapour pocket in suction line. Check suction line design for vapour pockets.
Air leaks into suction line. Check suction pipe is airtight.
Air leaks into pump through casing and pipework
gaskets. Check and replace faulty parts.
CONSULT FLOWSERVE.
Foot valve too small. Investigate replacing the foot valve.
Foot valve partially clogged. Clean foot valve.
Inlet of suction pipe insufficiently submerged. Check out system design.
Speed too low. CONSULT FLOWSERVE.
Speed too high. CONSULT FLOWSERVE.
Total head of system higher than differential head
of pump.
Total head of system lower than pump design head.
Check system losses.
Remedy or CONSULT FLOWSERVE.
Specific gravity of liquid different from design.
Viscosity of liquid differs from that for which
designed.
Check and CONSULT FLOWSERVE.
Operation at very low capacity or pump run dry.
Measure value and check minimum permitted.
Remedy or CONSULT FLOWSERVE.
Operation at high capacity.
Measure value and check maximum permitted.
Remedy or CONSULT FLOWSERVE.
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 are within acceptable values.
CONSULT FLOWSERVE.