Operating Faults And Their Possible Causes - Pratissoli LK Serie Manual De Uso Y Mantenimiento

15 OPERATING FAULTS AND THEIR
POSSIBLE CAUSES
The pump does not produce any noise upon
start-up:
- The pump is not primed and is running dry.
- No suction water.
- Valves are blocked.
- The outlet line is closed and does not allow air
present in the pump head to come out.
The pump pulsates irregularly:
- Air suction.
- Insufficient supply.
- Bends, elbow bends, fittings along the suction
line are choking the passage of liquid.
- The suction filter is dirty or too small.
- The booster pump, where installed, is supplying
insufficient pressure or flow rate.
- The pump is not primed for insufficient head or
the outlet is closed during priming.
- The pump is not primed due to valve jamming.
- Worn valves.
- Worn pressure seals.
- Imperfect functioning of the pressure control
valve.
- Problems on the transmission.
The pump does not supply the nominal flow rate/
excessive noise:
- Insufficient supply (see various causes as above).
- The number of rpms is less than the nominal rate;
- Excessive leakage of the pressure control valve.
- Worn valves.
- Excessive leakage of the pressure seals.
- Cavitation due to:
1) Improper sizing of suction ducts/undersized
diameters.
2) Insufficient flow rate.
3) High water temperature.
The pressure supplied by the pump is insufficient:
- Use (nozzle) is or has become higher than the
capacity of the pump.
- The number of rpms is insufficient.
- Excessive leakage of the pressure seals.
- Imperfect functioning of the pressure control
valve.
- Worn valves.
The pump is overheated:
- The pump is working in pressure excess or the
number of rpms is higher than the nominal rate.
- Oil in the pump casing is not at level or is not the
recommended type as detailed in chapter 7 (see
par. 7.6).
- Joint alignment is incorrect.
- Excessive pump tilt during operation.
Vibrations and shock to pipes:
- Air suction.
- Imperfect functioning of the pressure control
valve.
- Valve malfunction.
- Non-uniformity in the transmission motion.
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