Basic Method - Hitachi UTOPIA R32 Series Installation And Operation Manual

9.1 Basic Method

If the penetration of moisture is suspected, perform "Triple Evacuation Method" that is described
in the next paragraph.
• Connect the gauge manifold using charging hoses with a vacuum pump or a nitrogen cylinder to
the check joints of the liquid line and the gas line stop valve.
• Check for any gas leakage at the flare nut connection, by using nitrogen gas to increase the
pressure at 4.15 MPa for outdoor units inside of the field-supplied piping.
• Connect a manifold gauge and vacuum pump to the check joints.
• Continue vacuum pumping work until the pressure reaches 500 microns (0.5 mmHg) or lower
for one to two hours.
• After vacuum pumping work, stop the vacuum pumping and leave the gauge for one hour.
Check to ensure that the pressure in the manifold gauge does not increase.
• If the pressure inside the gauge does not maintain 500 microns (0.5 mmHg), it is considered that
there is a gas leakage. Check for any gas leakage once again.
• If no leakage exists, operate the vacuum pumping for one to two hours. If moisture remains
inside the pipes, the compressor may be damaged.
• Tighten the caps of check joint according to the specified torque after the vacuum pumping
work.

NOTE
• This system is only for the refrigerant R32. The manifold gauge and the charging hose should be
exclusive use for the corresponding refrigerant.
• If tools or measuring instruments come into contact with the refrigerant, use the tools or the
measuring instruments exclusively for the corresponding refrigerant.
• DO NOT perform vacuuming pumping work with valves of the outdoor units open. Otherwise,
the refrigerant charged before shipment may leak and it may result in failure.
• When the spindle cap for stop valve is removed, the gas accumulated at O-ring or screws is
released and may make sound. This phenomenon is NOT a gas leakage.
• If vacuum degree of 500 microns (0.5 mmHg) is not available, it is considered of gas leakage
or entering moisture. Check for any gas leakage once again. If no leakage exists, operate the
vacuum pump for more than one to two hours.
• Insulate the liquid pipe for prevention of the capacity decrease according to the ambient air
conditions and the dewing on the pipe surface by the low pressure.
PMEN0654 rev.0 - 12/2023
Heat pump system
RAS-(2-3)HVRC3
Gas stop valve
Liquid stop valve
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