Leak detection uses which of the following gases?

• A. HCFC-22
• B. CO2
• C. Ammonia
• D. R-134a

Answer: (A)

Leak detection relies on tracer gases that are easy for detectors to sense. Halogenated refrigerants serve well as tracers because electronic leak detectors are tuned to pick up their vapors. HCFC-22 is a common choice for this purpose, so it’s used to test for leaks and locate where refrigerant is escaping. It provides a detectable, controllable signal that helps technicians precisely track leaks and verify repairs.

The other gases listed aren’t the standard tracer for leak testing in typical HVAC practice. Carbon dioxide isn’t a halogenated tracer and isn’t what detector instruments are specifically designed to detect for leak checks. Ammonia, while used as a refrigerant in some systems, is toxic and isn’t used as a general tracer for leak detection. R-134a is itself a refrigerant, not the conventional tracer gas used to reveal leaks in the kind of leak-detection procedures described here.