Operating Faults And Their Possible Causes - Interpump Group SS70 Betriebs- Und Wartungsanleitung

5) defective installation
6) improper positioning or sizing of pipes
7) unauthorized design modifications
8) cavitation.
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 jammed.
- The outlet line is closed and does not allow the
release of air present in the pump manifold.
Pump pulsates irregularly:
- Air suction.
- Insufficient supply.
- Bends, elbows, fittings on the suction line are
choking the passage of liquid.
- Suction filter is dirty or too small.
- The booster pump, where installed, is supplying
insufficient pressure or flow rate.
- The pump is not primed due to 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).
- Pump speed is below the rated speed;
- Excessive internal leakage of pressure control
valve.
- Worn valves.
- Excessive leakage from 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:
- The user flow (nozzle) is or has become greater
than the pump capacity.
- Insufficient revolutions per minute.
- Excessive leakage from the pressure seals.
- Imperfect functioning of the pressure control
valve.
- Worn valves.
Pump overheats:
- The pump is working in overpressure conditions
or pump rpm is higher than the nominal value.
- Oil in the pump casing is not at level or not the
recommended type as detailed in chapter 7
(see par. 7.6).
- Excess belt tension or joint or pulley alignment is
incorrect.
- Excessive pump tilt during operation.
Vibrations or hammering on pipes:
- Air suction.
- Faulty operation of pressure control valve.
- Valves malfunction.
- Non-uniformity of transmission motion.
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