What is the purpose of purging the lines with nitrogen during brazing?

Purging the lines with nitrogen during brazing serves the important function of preventing the formation of copper oxide inside the lines. When materials such as copper are heated during the brazing process, there is a risk of oxidation, which can compromise the integrity and quality of the brazed joints. Nitrogen is an inert gas, meaning it does not react with the materials being joined. By displacing oxygen within the lines, nitrogen effectively creates a controlled atmosphere that prevents oxygen from coming into contact with the heated metal surfaces. This minimizes the likelihood of oxide formation, thereby ensuring a cleaner and more effective brazing process that yields stronger joints.

Other choices do not address the chemical interactions relevant to the brazing process or the specific need to maintain material quality. For instance, drying the lines or improving airflow does not directly relate to protecting the metal from oxidation during heat-induced processes. Additionally, while reducing pressure might be necessary in certain situations, it does not pertain to the primary benefits of using nitrogen in this context.