Flowserve MNV - Manual (Page 41)

MNV & MNZ USER INSTRUCTIONS ENGLISH 71569188 11/04
Page 41 of 47
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7 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
P u m p o ve r h e a ts a n d s e iz e s
⇓ ⇓ B e a r i n g s h ave s h o r t l i f e
⇓ ⇓ P u m p vi b r a t e s o r i s n o i sy
⇓ ⇓ M e c h a n i c al s e a l / g l a n d h a s s h o r t l i f e
⇓ ⇓ M e c h a n i c al s e a l / g l a n d l ea k s e x ce s s i ve l y
⇓ ⇓ P u m p r e q u i re s e x c es s i ve p ow e r
⇓ ⇓ P u m p l o s e s p r i m e a ft e r sta r t i n g
⇓ ⇓ I n s u f f i c i e n t d i s c h a r g e pre s s u r e d e ve l o p e d
⇓ ⇓ I n s u f f i c i e n t c a pa c i t y d e l i ve r e d
⇓ ⇓ P u m p d o e s no t d e l i ve r l i q u i d
⇓ ⇓
PROBABLE CAUSES POSSIBLE REMEDIES
A. System troubles
Pump not primed.
Pump or suction pipe not completely filled with
liquid or valves not fully open.
Check and fill with liquid completely. 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 inlet 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 mechanical seal,
sleeve joints, casing joint or pipe plugs.
Check and replace faulty parts. Refer to Seal User
Instructions/Consult Flowserve.
Impeller, casing piping partially /fully clogged. Investigate replacing the valve.
Inlet of suction pipe insufficiently submerged. Clean /open valve as required.
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. 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 and/or critical
frequency of the system excited.
Check setting of baseplate: tighten, adjust, grout
base as required. Resonance tests
Shaft bent. Check shaft runouts are within acceptable values
Consult Flowserve.
Rotating part rubbing on stationary part internally. Check and Consult Flowserve, if necessary.
Bearings worn Replace bearings.