501-A00 Page 11/12
PUMP TROUBLESHOOTING
NOTICE:
Maintenance shall be performed by qualified technicians only,
following the appropriate procedures and warnings as presented in this manual.
SYMPTOM PROBABLE
CAUSE
Pump Not Priming
1. Pump not wetted.
2. Worn
vanes.
3. Internal control valve closed.
4. Strainer
clogged.
5. Inlet line or valves clogged or too restrictive.
6. Pump
vapor-locked.
7. Pump speed too low for priming.
8. Relief valve partially open, worn or not seating properly.
Reduced Capacity
1. Pump speed too low.
2. Internal control valve not fully open.
3. Excessive restriction in the inlet line (i.e.: undersized piping, too many elbows &
fittings, clogged strainer, etc.).
4. Damaged or worn parts (vanes, cylinder, or rotor).
5. Excessive restriction in discharge line causing partial flow through the relief valve.
6. Relief Valve worn, set too low, or not seating properly.
7. External Bypass Valve set too low.
8. Operating
without
a vapor return line.
9. Vanes installed incorrectly (see "Vane Replacement").
Noise
1. Excessive pressure drop on the pump due to:
a. Undersized or restricted fittings in the inlet line.
b. Pump speed too fast.
c.
Pump too far from fluid source.
2. Running the pump for extended periods with a closed discharge line.
3. Pump not securely mounted.
4. Misalignment of pump, or motor - base mounted pumps.
5. Bearings worn or damaged.
6. Vibration from improperly anchored piping.
7. Bent shaft, or drive coupling misaligned.
8. Excessively worn rotor.
9. Malfunctioning valve in the system.
10. Relief valve setting too low.
11. Damaged vanes (see following category).
Damaged Vanes
1. Foreign
objects
entering the pump.
2. Running the pump dry for extended periods of time.
3. Cavitation.
4. Excessive
heat.
5. Hydraulic hammer - pressure spikes.
6. Vanes installed incorrectly (see "Vane Replacement").
7. Incompatibility
with the liquids pumped.
Broken Shaft
1. Foreign
objects
entering the pump.
2. Relief valve not opening.
3. Hydraulic hammer - pressure spikes.
4. Pump/driver shaft misalignment.
5. Excessively worn vanes or vane slots.
Mechanical Seal Leakage
1. O-rings not compatible with the liquids pumped.
2. O-rings nicked, cut or twisted.
3. Shaft at seal area damaged, worn or dirty.
4. Ball bearings overgreased.
5. Excessive
cavitation.
6. Mechanical seal faces cracked, scratched, pitted or dirty.
Overload on Motor
1. Motor Horsepower not sufficient for application.
2. Improper wiring and/or low voltage to motor.
3. Misalignment
4. Excessive pressure or speed.
5. Bearing
locknuts
adjusted improperly.
6. Faulty or worn bearings.
7. Rotor rubbing against head or cylinder.
8. Dirty mechanical seal faces.
