Operating Faults And Their Possible Causes - Pratissoli MK9M Serie Manual De Uso

a) The pump is used for purposes other than for those agreed
upon.
b) The pump is fitted with an electric or combustion motor
with performance exceeding those indicated in the table.
c) Safety devices are decalibrated or disconnected.
d) The pump is used with accessories or parts not supplied
by Interpump Group.
e) Damage has been caused by:
1) improper use
2) failure to follow maintenance instructions
3) any use different from that described in the operating
instructions
4) lack of sufficient flow rate (suction)
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 prime upon start-up:
- The pump is not primed and is running dry, rpm
too high - see graph in par. 9.8.
- No suction bentonite.
- 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 pump is not primed for insufficient head.
- 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 fluid temperature.
The pressure supplied by the pump is insufficient:
- Use 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 not the
recommended type as detailed in chapter 7 (see
par. 7.6).
- Joint or pulley 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.
27