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D.
PUMP OVERLOADS DRIVER
Possible Causes
Corrective Action
1. Speed too high..
Check driver and verify correct size for required speed.
2. Specific gravity too high.
Check. This can cause overloading.
3. Head lower than rating, pumps too much liquid..
Pump may be operating at a higher flow rate than
suspected. Throttle pump at discharge to reduce flow.
4. High viscosity.
Check. This can cause high drag on the rotor, rotor
cover and pick-up tube.
5. Electrical defects.
The voltage and frequency of the electric motor may be
lower than that for which the motor was built. The
motor may not be ventilated properly due to a poor
location.
E.
PUMP WORKS FOR A WHILE THEN QUITS
Possible Causes
Corrective Action
1. Incomplete priming
Free pump, piping and valves of all air. If high points in
suction line prevent this, they need correcting.
2. Suction lift too high.
If no obstruction at inlet, check for pipe friction losses.
However, static lift may be too great. Measure with
mercury column or vacuum gauge while pump
operates. If static lift is too high, liquid to be pumped
must be raised or pump lowered.
3. Air leak in suction line.
Suction line can be tested by shutting off or plugging
inlet and putting line under pressure. A gauge will
indicate a leak with a drop of pressure.
4. Air or gases in liquid.
May be possible to over rate pump to point where it will
provide adequate pressure despite condition. Better to
provide gas separation chamber on suction line near
pump.
5. Mechanical failure of critical pump parts.
Check bearings and pick-up tube for damage.
