LG Multi V ACRUN040LSS0 Installation Manual page 26

INSTALLATION
26
Nitrogen substitution method
Welding, as when heating without nitrogen substitution a large amount of the oxide film is
formed on the internal piping.
The oxide film is a caused by clogging EEV, Capillary, oil hole of accumulator and suction hole of
oil pump in compressor.
It prevents normal operation of the compressor.
In order to avoid this problem, Welding should be done after replacing air by nitrogen gas.
When welding plumbing pipe, the work is required.
Oxide scale
Note) should not block the outlet side.
When the internal pressure in pipe is above
the atmospheric pressure, pinhole is
occurred and it is a leakage cause.
CAUTION
!
1 Always use the nitrogen.(not use oxygen, carbon dioxide, and a Chevron gas):
Please use the following nitrogen pressure 0.02 MPa.
Oxygen – Promotes oxidative degradation of refrigerant oil.
Because it is flammable, it is strictly prohibited to use.
Carbon dioxide – Degrade the drying characteristics of gas.
Chevron Gas – Toxic gas occurs when exposed to direct flame.
2 Always use a pressure reducing valve.
3 Please do not use commercially available antioxidant.
The residual material seems to be the oxide scale is observed.
In fact, due to the organic acids generated by oxidation of the alcohol contained in the anti-
oxidants, ants nest corrosion occurs. (causes of organic acid → alcohol + copper + water +
temperature)
Welding Point
Taping
(Should not
contain air)
Regulator
Nitrogen gas
Pressure 0.02 MPa less
Auxiliary valve