Friends who produce copper pipe fittings know that nitrogen is good, but why do you use nitrogen protective welding?
First, to prevent high temperature oxidation of metal, oxidized metal is very easy to fall off in the pipeline, causing pipeline blockage, injecting nitrogen, carbon dioxide or inert gas can prevent metal oxidation at high temperature welding.

Second, the internal nitrogen protection when welding, nitrogen is flowing (generally in high purity nitrogen according to 0.05MPA vent), we made a small tool here, the oxygen in the copper pipe to extrusion, to prevent the inner wall of the copper pipe in the heating process to generate oxide skin. Because the presence of large particles in the pipe (fluorine side) will block the compressor, causing the compressor (compressor price is second only to the evaporator and condenser) to burn out, so the cleanliness control of the fluorine side is quite strict.
Then the amount of bottled nitrogen is very large, and the bottled nitrogen needs to be replaced every day, which is expensive.
It is recommended to use a nitrogen machine, which is a equipment that produces nitrogen, and a nitrogen system can be used for 8-10 years without personnel on duty.