Flowserve ERPN-M - Manual (Page 32)

ERPN-M USER INSTRUCTIONS ENGLISH 02-08
Page 32 of 37
8.0 FAULTS; CAUSES AND REMEDIES
FAULT SYMPTOM
Pump overheats and seizes
⇓ ⇓ Bearings have short life
⇓ ⇓ Pump vibrates or is noisy
⇓ ⇓ Magnetic coupling has short life
⇓ ⇓ Magnetic coupling 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
z z Pump not primed. Check complete filling
z z z z Pump or suction pipe not completely filled with
liquid.
Check and complete filling
z z z z z
Suction lift too high or level too low.
Check NPSHa>NPSHr, proper submergence,
losses at strainers / fittings
z z z Excessive amount of air or gas in liquid. Check and purge from pipes
z z z Air or vapour pocket in suction line. Check suction line design for pockets
z z Air leaks into suction line. Check airtight pipe then joints and gaskets
z z Air leaks into pump through mechanical seal,
sleeve joints, casing joint or pipe lugs.
Check airtight assembly then joints and
gaskets
z z Foot valve too small. Investigate replacing the foot valve
z z Foot valve partially clogged. Clean foot valve
z z z z Inlet of suction pipe insufficiently submerged. Check cut out system design
z z z
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
z Total head of system lower than pump design
head.
Throttle at discharge valve or ask Flowserve if
the impeller can be trimmed
z Specific gravity of liquid different from design. Consult Flowserve
z z z Viscosity of liquid differs from that for which
designed.
Consult Flowserve
z z Operation at very low capacity. Measure value and check minimum permitted
z z z
Operation at high capacity.
Measure value and check maximum
permitted
B. MECHANICAL TROUBLES
z z z z z z
Misalignment due to pipe strain.
Check the flange connections and eliminate
strains using elastic couplings or a method
permitted
z
Improperly designed foundation.
Check setting of baseplate: tighten, adjust,
grout base as required
z z z z z Shaft bent. Check shaft runouts within acceptable values
z z z z Rotating part rubbing on stationary part
internally.
Check for signs of this and consult Flowserve
if necessary
z z z z z Bearings worn Replace bearings
z z z Wearing ring surfaces worn. Replace worn wear ring/ surfaces
z z z Impeller damaged or eroded. Replace impeller and check reason
z Leakage under sleeve due to joint failure. Replace joint and check for damage
z z z
Magnetic coupling improperly installed.
Check alignment of faces or damaged parts
and assembly method used