NATE Air Conditioning and Heat Pumps Practice Exam

The recommended flame for brazing refrigerant piping is a neutral flame. A neutral flame is characterized by having a balanced ratio of oxygen and acetylene, resulting in complete combustion. This type of flame produces a clear, cone-shaped inner core that is neither oxidizing nor carbonizing, which helps prevent damage to the metal being joined. When brazing, it's crucial to maintain an appropriate temperature without introducing excess oxygen or carbon that could lead to oxidation or contamination of the base metals. Using a neutral flame ensures that the heat applied is effective for melting the filler metal while preserving the integrity of the components being brazed, thus creating strong and reliable joints in refrigerant piping systems. This approach minimizes the risk of forming oxides or carbon deposits that could compromise the system's performance.