Which refrigerant is not miscible with mineral oil?

R-134A is the correct choice because it is a hydrofluorocarbon (HFC) refrigerant that is not miscible with mineral oil. This is an important characteristic in refrigeration systems, as the lubricating oil must mix well with the refrigerant to ensure proper circulation and lubrication of the compressor. Since R-134A does not mix with mineral oil, it typically requires a synthetic oil for optimal performance, which can properly lubricate the compressor and reduce wear.

In contrast, R-12, R-22, and R-410A are refrigerants that can be mixed with mineral oil. These refrigerants contain chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which exhibit good miscibility with mineral oil, facilitating effective lubrication within the system. It’s crucial for technicians to understand the compatibility between refrigerants and oils to ensure the longevity and efficiency of refrigeration equipment.