Mitsubishi Heavy Industries SRRM40HENG-L, Handbook, Page: 1059 / 1106

1057
FDC-HKXR
(4) Heat insulation
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Exterior tape
Use insulation material with good resistance heat properties (120 ˚C or more).
Gas lines
Liquid piping
Wires for connecting indoor
and outdoor units
Insulation
(i) There is a need to insulate both gas and liquid piping with heat insulation for protection against heat and
condensation.
1) Always use heat insulation to prevent condensation on the gas piping from becoming drain water and
causing leakage during cooling and to prevent people from being burned by the high temperature of the
surface of the gas piping as discharge gas flows through it.
2) Use heat insulation (pipe cover) on the flare connection sections of the indoor unit.
(Insulate both the gas and liquid piping.)
3) Insulate both the gas and liquid piping. Apply the insulation so that is tight against the piping and free of
gaps. Route the connecting wires with the insulation and wrap the entire bundle with exterior tape.
(5) Air-tight test
(a) When conducting an air-tight test of local piping, connect the piping to the check joint of the evacuating pipe connected to
the gas side service valve, and keep the service valve closed. The air-tight test pressure shall be 3.23MPa(33 kgf/cm
2
.)
(b) To conduct the test, pressurize the check joint of evacuating pipe by nitrogen gas as shown below. The local piping
including indoor units can be tested as for airtightness.
(6) Evacuating
Evacuating can be completed faster by evacuating both the check joint on the liquid side service valve and the check joint of the
evacuating gas pipe (accessory) connected to the gas side operation valve at the same time. (Of course, evacuating is possible
even through the liquid side check joint only.)