To prevent oxidation when brazing, what method should be employed?

Using a nitrogen sweep during brazing is an effective method to prevent oxidation. When heating metals like copper or brass in a brazing process, these materials can react with oxygen at high temperatures, leading to undesirable oxidation. Oxidation can hinder proper adhesion and significantly weaken the joint.

A nitrogen sweep introduces an inert atmosphere around the area being brazed. This inert nitrogen displaces the oxygen, thereby reducing the chances of oxidation occurring during the high-temperature process. The nitrogen is also inexpensive and accessible, making it a practical choice in many HVAC applications.

While other methods exist for reducing oxidation, like using an argon shield, nitrogen is particularly favored for its straightforward application and effectiveness in displacing oxygen during heating.