SPP Pumps Unistream - Manual (Page 15)

Operators Instructions for
Unistream Centrifugal Pumps
Manual No/Rev
W21-002E / 10
Our policy is one of continuous improvement and we reserve the right to alter specifications at any time
Page 15 of 24
CAUSE REMEDIAL ACTION
Pump not
primed. Fill pump and suction pipe
completely with fluid.
Speed too
low. Check that the motor is
correctly connected and
receiving the full supply voltage
also confirm that the supply
frequency is correct.
Speed too
high. Check the motor voltage.
Air leak in
suction
pipework Check each flange for suction
draught, rectify as necessary.
Air leak in
mechanical
seal. Check all joints, plugs and
flushing lines, if fitted. Note that
prolonged running with air in
the mechanical seal will result
in damage and failure of the
seal.
Air or gas in
liquid. It may be possible to increase
the pump performance to
provide adequate pumping.
Discharge
head too high
(above rating). Check that valves are fully
open and for pipe friction
losses. An increase in pipe
diameter may reduce the
discharge pressure.
Suction lift too
high. Check for obstruction of pump
inlet and for inlet pipe friction
losses. Measure the static lift, if
above rating, raise the liquid
level or lower the pump.
Not enough
head for hot
liquid. Reduce the positive suction
head by raising the liquid level.
Inlet pipe not
submerged
enough. If the pump inlet cannot be
lowered, provide a baffle to
smother the inlet vortex and
prevent air entering with the
liquid.
Viscosity of
liquid greater
than rating Refer to SPP Pumps Ltd. for
guidance to increase the size
or power of the motor or
engine.
Liquid density
higher than
rating. Refer to SPP Pumps Ltd. for
guidance to increase the size
or power of the motor or
engine.
Insufficient
nett inlet head. Increase the positive suction
head by lowering the pump or
raising the liquid level.
Impeller
blocked. Dismantle pump and clean the
impeller.
Wrong
direction of
rotation. Check driver rotation with the
direction arrow on the pump
casing.
CAUSE REMEDIAL ACTION
Excessive
wear ring
clearance. Replace the wear rings and/or
the impeller when the
clearance exceeds the
maximum adjustment.
Damaged
impeller. Replace if damaged or vanes
are eroded.
Rotor binding. Check for shaft deflection,
check and replace bearings if
necessary.
Defects in
motor. Ensure that motor is
adequately ventilated. Refer to
manufacturers instructions.
Voltage and/or
frequency
lower than
rating. If voltage and frequency are
lower than the motor rating,
arrange for provision of correct
supply.
Lubricating oil
dirty or
contaminated. Dismantle the pump, clean the
bearings, reassemble the pump
and fill with new oil.
Foundation
not rigid. Ensure that the foundation
bolts are tight; check that
foundations match SPP Pumps
Ltd. recommendations.
Misalignment
of pump and
driver. Realign the pump and driver as
specified.
Bearings
worn. Remove the bearings, clean
and inspect for damage and
wear, replace as necessary.
Rotor out of
balance. Check impeller for damage,
replace as necessary.
Shaft bent. Check shaft run-out and
replace if needed.
Impeller too
small. Refer to SPP Pumps Ltd. for
options to fit a larger impeller.