Two gases that considered non-condensable in a refrigeration

• A. Oxygen and Argon
• B. Air and Nitrogen
• C. Carbon Dioxide and Helium
• D. Hydrogen and Methane

Answer: (B)

Non-condensable gases are those that do not condense at the temperatures and pressures inside a refrigeration system. In practice, air leaks into the refrigerant circuit and stays as gas, occupying space in the condenser and reducing heat transfer efficiency. The classic non-condensables you’ll encounter in HVAC work are the components of air, especially nitrogen, since they do not condense under normal condenser operating conditions. Air is primarily nitrogen and oxygen, so saying air and nitrogen captures the common non-condensable scenario you must manage. The other gases listed are either not typical non-condensables in routine systems or are used as refrigerants themselves, so they aren’t the standard examples you’d look for in this context.