7 Troubleshooting
7.1 Pump Troubleshooting
Table 8: Pump Troubleshooting
Symptom
Cause
Remedy
No liquid delivered or intermittent flow
Pump not primed or prime lost, liquid
level does not completely fill elbow
Fill system piping completely so the
impeller is submerged
Suction inlet clogged
Remove obstructions from pump inlet
Impeller clogged with foreign material Back flush pump or manually clean
impeller
Suction and /or discharge valve
closed or clogged
Open valves to remove shut-off con-
dition
Wrong direction of rotation
Change rotation to concur with direc-
tion indicated by the arrow on the
bearing housing
Suction piping incorrect
Replace or modify suction piping
Insufficient NPSH available
Increase liquid level or lower pump
Air leak in suction line
Test suction piping for leaks
Speed (rpm) too low
New drive or gear box to obtain high-
er pump speed
Excess air entrapped in liquid
Install vent in piping or eliminate air
source
Pump not producing rated flow or
head
Impeller partly clogged
Back flush pump or manually clean
impeller
Insufficient suction head
Fill system piping so the liquid level is
above the pump impeller centerline
Pump not primed or prime lost, pump
does not completely fill elbow
Fill system piping completely so the
impeller is submerged
Suction and/or discharge valve
closed or clogged
Open valves to remove partially
blocked condition
Suction piping incorrect
Replace or modify suction piping
Excessive air entrapped in liquid
Install vent in piping or eliminate air
source
Speed (rpm) too low
New drive or gear box to obtain high-
er pump speed
Incorrect rotation
Check motor wiring
Incorrect impeller or impeller diameter Check vane angles and/ or impeller
clearances
System head too high
Check system curve calculations, re-
duce system resistance
Instruments give erroneous readings Check and calibrate instruments, re-
place if necessary
Worn or broken impeller, bent vanes
Inspect and replace if necessary
Pump assembled incorrectly
Compare pump assembly to instruc-
tion manual
Wear of internal wetted parts is accel-
erated
Insufficient NPSH available
Increase liquid level or lower pump
Chemicals in liquid other than speci-
fied
Analyze pumpage and correct or
change pump wet end materials to
suit pumpage composition
7 Troubleshooting
Model AF (42"/1200mm/54"/60"/66") LM/LMR Bearings Installation, Operation, and Maintenance Manual
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