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5- SAFETY DEVICES AND MALFUNCTIONIG PREVENTION
5.1 SAFETY DEVICES
The system incorporating pump must always be provided with the following safety
devices:
Safety valve: It is a pressure relief valve, properly calibrated, able to discharge the
excessive pressure in case of fault in the high-pressure circuit.
Pump shaft protection: This kind of protection keeps the operator from accidental
contact with the moving parts of the shaft and the driving.
Pressure regulation valve: This valve permits to regulate the working pressure and
allows the excessive fluid to flow back in the reservoir, preventing dangerous pres-
sures.
5.2 MALFUNCTIONING PREVENTION
5.2 A) OVERPRESSURES PROTECTION:
The pump is a volumetric type, and the same quantity of fluid always comes out at every
shaft turn. Since the fluids are incompressible, if fragments accidentally clog the nozzle,
keeping the fluid out, the plungers would push towards a solid component. If a protection
valve is missing, the pump would immediately destroy itself.
Safety valve.
A safety valve of proper quality and size prevents this kind of problems.
If during the normal use (e.g. with a washing gun and a lance) the supply is frequent-
ly interrupted, the water circulates through the pressure relief valve at the set pres-
sure, causing overheating and consequently damaging the pump.
By-pass and Pressure Regulating Automatic Valve.
An automatic valve reduces this problem because, in this kind of valve, the water cir-
culates at a very low pressure, and the water overheats in a longer time.
5.2 B) PROTECTION FROM ABRASIVE PARTICLES
Water always has impurities and abrasive particles, also when it is drinking water.
The abrasive particles not only damage the seals, but also wear the check valves, the regu-
lating valve and the nozzle, in a very short time.
A properly sized filter, installed next to the pump, assures a long life to all the sys-
tem.
Remind the filter must be always efficient, clean and periodically controlled
depending on the use of the pump.
5.2 C) PROTECTION FROM PULSATIONS
A pressure damper charged at 50-60% of the working pressure damps the whole hydraulic
system vibrations, thus reducing the stress on the system.
5.2 D) PROTECTION FROM CAVITATION (NPHSr)
The cavitation is generated by the formation of gas pockets in the supply circuit, and wears
the gaskets and the metal parts of the pump. The clearer consequence is a continuous or
intermitting hammering, coming from the pump.
Performances, pressure and flow often reduce or become intermittent.
All the fluids tend to generate steam and this is particularly clear when temperature is rising
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