35
6.5 Troubleshooting
Problem
Cause
Remedy
Pump does not
deliver or deliv-
ers at a reduced
rate.
1. Incorrect electrical hook-up (2 phases).
2. Wrong rotational direction.
3. Air in the suction line or in the pump.
4. Back pressure too high.
5. Insufficient suction head.
6. Lines clogged or foreign material in the
impeller.
7. Air inclusions as a result of a defective
seal.
1. Check the electrical connections and
correct them if necessary.
2. Reverse the phases of the power supply
(reverse the polarity).
3. Vent the suction line or the pump and refill.
4. Reset the operating point according to the
data sheet. Check system for
contamination.
5. Raise the liquid level on the suction side.
Open the shut-off valve in the suction line
all the way.
Produce the conditions described in
chapter 5.1. Consult manufacturer.
6. Open the pump and fix the problem.
7. Check the pipeline seals, the pump
housing seals, and the shaft seals.
Replace if necessary.
Motor safety
switch turns
motor off. Motor
is overloaded.
1. Pump jammed because of clogging.
2. Pump jammed by contact because pump
body was twisted by the pipelines. (Check
for damage).
3. Pump continues to run beyond the rated
operating point.
4. The density or viscosity of the pumping
medium is higher than
the pump was
intended for.
5. Motor safety switch not properly adjusted.
6. Motor running on 2 phases.
1. Open the pump and fix the problem.
2. Install the pump so that there is no stress
on it. Support the pipelines at fixed points.
3. Set the operating point according to the
data sheet.
4. If it is acceptable for the performance to be
lower than that stated, decrease the
delivery rate on the pressure side.
Otherwise, use a more powerful motor.
Consult manufacturer.
5. Check the setting. Replace the safety
switch if necessary.
6. Check the electrical connections. Replace
defective fuses.
Pump produces
too much noise.
Pump runs
roughly and
vibrates.
1. Insufficient suction head.
2. Air in the suction line or in the pump.
3. Back pressure lower than stated.
4. Impeller out of balance.
5. Internal parts worn.
6. Pump is twisted (causing contact noises).
Check for damage.
7. Bearings are defective.
8. Bearings have too little, too much, or the
wrong kind of lubricant.
9. Motor cooling fan defective.
10. Foreign material in the pump.
1. Raise the liquid level on the suction side.
Open the shut-off valve in the suction line
all the way.
Produce the conditions described in
Section chapter 5.1. Consult manufacturer.
2. Vent the suction line or the pump and refill.
3. Set the operating point according to the
data sheet.
4. Clean, inspect, and re balance the
impeller.
5. Replace parts.
6. Install the pump so that there is no stress
on it. Support the pipelines at fixed points.
7. Replace the bearings.
8. Add more lubricant, decrease the amount,
or replace the lubricant.
9. Replace the motor cooling fan.
10. Open the pump and clean it (install a
screen in front of self-priming pumps, if
necessary).
Tab. 5
Troubleshoo ing
