What is the recommended practice for brazing or welding during installation of B28 systems?

• A. Use inert-gas purge, perform away from flammable refrigerants, and follow manufacturer procedures to prevent ignition.
• B. Use open flame near refrigerants to ease brazing.
• C. Do brazing indoors without purge.
• D. Ignore manufacturer procedures.

Answer: (A)

During brazing or welding on B28 systems, the biggest safety concern is ignition of flammable refrigerants. Using an inert-gas purge around the joint helps create a nonflammable environment by displacing air and reducing oxygen and hydrocarbon vapor concentration, which lowers the ignition risk. Performing the work away from any flammable refrigerant sources further minimizes exposure to vapors that could ignite if exposed to a hot flame. Following the manufacturer’s procedures is essential because they specify the correct purge gas, purge duration, equipment, and post-braze steps like leak testing and venting to ensure the system remains safe after the repair.

Other approaches—using an open flame near refrigerants, brazing indoors without any purge, or ignoring procedures—significantly raise the chance of ignition and are unsafe.