McQuay MDS030AR Applications Manual page 83

Moisture
4.3.3 Exchange Way of Nitrogen Gas (When Welding Copper Tube)
Suppose no nitrogen gas is injected into refrigerant pipe when welding, the oxide air bubble will
come into being in the internal surface of tube. This will result in some damage to the system. In
order to avoid these, nitrogen gas should be injected into refrigerant pipe when welding, this
process is called nitrogen gas exchange method. This is the standard operation process of
welding.
Pressure adjustor
Pipe
Nitrogen bottle
Note:
The gas must be Nitrogen.
Pressure adjustor must be used.
Copper
Non-hermetic valve
High pressure pipe
Nitrogen bottle
Non-hermetic valve
Pipe
Pressure adjustor
Design & installation Guide For McQuay MDS Multi System
Dust
unit's connecting pipe
Binding belt welding area
Outdoor unit
Air
leakage
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