High Pressure Circuit - Bertolini LIGHT DUTY Serie Manual Del Usuario

4.4 HIGH-PRESSURE CIRCUIT
All the parts of the high-pressure circuit must be sized for minimum performances, (pressure and
flow) at least 30% more than the pump performances.
it is necessary to fit a pressure regulating valve set at the working pressure. This valve permits the
excessive fluid to flow back in the tank, preventing that dangerous pressures arise. It is quite nor-
mal that the pump flow is "oversized" than the actual need. For correct running of the system, the
water recycled through the regulating valve should not exceed 10-15% of the pump flow. Other-
wise, besides the useless energy waste, water overheating will be generated in the suction tank,
thus increasing the cavitation risks.
For your and for the system safety it is necessary to fit on this circuit a safety valve set at a
pressure of 15-25% more than the setting value of the regulating valve. The safety valve and
the regulating valve must carryover the stamping of the name of the manufacturer and the max.
rated pressure, the max admissible flow and temperature.
In case the safety valve frequently releases, immediately stop the pump and check the system with
the help of a skilled technician.
 Do not connect the safety valve by-pass and the regulating valve by-pass to the inlet line.
 Especially using an automatic regulating valve we recommended to fit, immediately after the
pump, a properly sized pulsation damper.
It is important to fit a pulsation damper precharged at 50-60% of the pump working pressure,
able to damp the vibrations of the whole hydraulic system. It must be sized according to the pump
performances and to the instructions provided by the manufacturer.
On the body the following information must be stamped: manufacturer brand, max pressure al-
lowed, test pressure, pre-charge pressure, capacity and manufacturing date. When tests are fore-
seen, the serial number and the test initials required in the country where the machine is installed
must appear as well.
 We recommend to install in the first part of piping flexible hoses, able to isolate the rest of the
system from the vibrations caused by the pump-engine/motor unit.
The flexible hoses must be mechanically seamed by the manufacturer, and the following infor-
mation must be stamped: the name of the manufacturer, the manufacturing date, the rated pres-
sure and the maximum admissible temperature.
 Use pressure gauges in glycerine bath able to stand pulsating pressures.
 The discharge line must be provided with a low pressure by-pass device to evacuate rapidly the
air in the pump head and to facilitate priming.
The high pressure circuit is subject to pressure losses caused by its structure; therefore it is normal that
the working pressure is lower than the pressure of the pump head.
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