What is an EPA approved trace gas used with nitrogen for leak detection?

• A. R-134A
• B. R-410A
• C. R-22
• D. R-12

Answer: (C)

The correct choice identifies R-22 as an EPA-approved trace gas used with nitrogen for leak detection. When technicians employ nitrogen to pressurize a refrigeration system, adding a trace gas aids in identifying leaks. R-22 is recognized for this application because it is a refrigerant that can be detected easily due to its distinctiveness in comparison to nitrogen and the refrigerants in the system.

Using a trace gas is effective in pinpointing small leaks that might not be easily identifiable with nitrogen alone, as the gas will escape through any openings in the system, enabling detection through electronic leak detectors or soapy water methods.

The other refrigerants mentioned in the options, such as R-134A, R-410A, and R-12, do not serve the role of a trace gas for detection in the same way. They are primarily used as working refrigerants in different applications rather than for leak detection purposes.