What gas is recommended to continuously purge during brazing?

When brazing, it is important to maintain a protective atmosphere to prevent oxidation and contamination of the base metals and the filler material. This is where the continuous purging with a suitable gas comes into play. Oil-free dry nitrogen is the recommended gas for continuous purging during brazing because it is inert, meaning it does not react with either the metal being joined or the filler metal.

Using dry nitrogen helps to displace any oxygen present in the braze zone, which would otherwise lead to the formation of oxides that can compromise the strength and integrity of the joint. Argon is also an inert gas but is typically more expensive and might not be necessary for typical brazing processes. Oxygen is reactive and would be harmful in a brazing environment, as it would promote oxidation. Carbon dioxide, while sometimes used in welding processes, can introduce impurities and does not provide the same protective benefits as dry nitrogen.

Therefore, oil-free dry nitrogen serves as an effective and economical choice for ensuring a clean and high-quality brazed joint.