Section
140 • 180
Page 511
Dated
October 2011
are evident, back off evenly until
the pump runs smoothly again.
Lock the bearing arm in place by
turning the two jam nuts (#20.5)
in a counterclockwise direction.
The bearing arm is now correctly
positioned and should remain so
until service is again required.
6. Evenly tighten the two nuts
(#20) on the discharge end of
the bearing arm. With a new
pump or one with new rings and
impellers, these nuts cannot
be tightened very much before
distress becomes noticeable.
Back off slightly until the pump
runs smoothly. Use the two jam
nuts (#20.5) to lock this bearing
arm in position as was done in
step #5. On an older pump, the
nuts (#20) on both ends may be
tightened up to 20 foot pounds.
Depending on the condition of the
pump, tightening these nuts can
improve and sometimes restore
performance. Jam nuts (#20.5)
should always be loose enough
to allow sensitive adjustment of
bearing arms when performing
these operations. Turn them
counterclockwise until they contact
bearing arms when adjustments
are complete.
7. This completes the necessary
adjustments. The pump is now
ready for service.
8. If an Amprobe or other current
measuring device is used as
the system is returned to normal
operation, a variation or wavering
will be noticed as the pump
impellers seek their hydraulic
balance. It sometimes requires
a few hours or even days to
complete this positioning.
5.
140 • 180 SERIES
Troubleshooting
FLEXIBLE COUPLED PUMPS
A.
Failure to Pump
B.
Reduced Capacity
C.
Reduced Pressure
D.
Pump Loses Prime After Starting
E.
Excessive Power Consumption
F.
Pump Vibrates or is Noisy
G.
Mechanical Problems
H.
Seal Leakage
5A Failure to Pump
1. Pump not up to speed — Use
Tachometer to determine actual
RPM. Check voltage and wiring
connections.
2. Pump not primed — Confirm
that pump and all inlet piping are
filled with fluid.
3. Discharge head too high
— Install a pressure gauge at
the pump discharge to determine
the actual operating pressure.
Compare readings with pump
performance curve. A larger
pump may be necessary.
4. Excessive suction lift —
Relocate pump, supply tank, or
both to minimize suction lift.
5. Wrong direction of rotation
— Compare pump rotation
with arrow on pump. Standard
pumps rotate in a clockwise
direction when looking at the
shaft extension end or from the
motor end on close-coupled
pumps. Reverse two leads
on a three-phase motor to
change rotation. Check motor
nameplate for single-phase
operation.
6. Clogged suction line, strainer, or
foot valve — Inspect and clean
out if necessary.
7. Air pocket in suction line
— Look for high spots in inlet
piping system. Evacuate the
system with a vacuum pump if
necessary.
5B Reduced Capacity
1. Pump not up to speed — Use a
tachometer to determine actual
RPM. Check voltage and wiring
connections.
2. Excessive suction lift —
Relocate pump, supply tank, or
both to minimize suction lift.
3. Insufficient NPSH — Relocate
pump, supply tank, or both
to improve NPSH available
if possible. Increase suction
pressure. Reduce fluid
temperature. Select a pump with
lower NPSH requirements.
4. Mechanical damage — Rotate
the pump by hand to determine
if there are tight spots. Broken
or bent impeller vanes can
sometimes be detected in this
manner. If there is a suspicion
of damage, remove the pump
from service and disassemble for
inspection.
5. Air leak in the suction line
— Fill the system with fluid and
hydrostatically test. Tighten
connections or replace leaky
components.
6. Air pockets in the suction piping
— Operating the system at
maximum flow conditions will
usually clear the lines. Evacuate
the system with a vacuum pump
if necessary.
7. Suction lines, strainer, or foot
valve too small or clogged
— Inspect and clean out as
necessary. Fittings and lines
should be at least equal to the
pump suction size.
8. Discharge head too high
— Install a pressure gauge at
the pump discharge to determine
the actual operating pressure.
Compare readings with pump
performance curve. A larger
pump may be necessary.
9. Excessive wear — If a pump
had previously performed
satisfactorily and now
gives evidence of reduced
performance, it should be
disassembled and examined
for wear after more simple
possible problems have been
investigated.
5C Reduced Pressure
1. Pump not up to speed — Use a
tachometer to determine actual
RPM. Check voltage and wiring
connections.
