r12

R12 is a designation used in several distinct domains, and its meaning depends on the context. Prominent uses include a chemical refrigerant designation and an automobile model name, among others.

One well known use is R-12, the chemical dichlorodifluoromethane, a chlorofluorocarbon formerly common as a refrigerant in automotive and domestic air conditioning systems. R-12 was phased out under international environmental agreements beginning in the 1990s due to its ozone-depleting potential. It has largely been replaced by non-ozone-depleting refrigerants such as R-134a and newer low-global-warming-potential blends. Handling and disposal of legacy equipment containing R-12 require proper procedures to prevent ozone damage and health risks, as the gas can act as an asphyxiant in confined spaces.

R12 is also the model designation for the Renault 12, a mid-size car produced by the French manufacturer Renault starting in 1969. The Renault 12 was offered in various body styles and markets around the world and became a significant volume model for the company during its production run. It was gradually phased out and succeeded by newer Renault models in the early 1980s and beyond.

Beyond these, R12 appears as a general alphanumeric label used in different technical and geographic coding systems. In electronics, for example, a reference designator such as R12 may name a resistor on a circuit board, while in transportation networks, similar prefixes are used for regional or route numbers in some countries. The exact meaning of R12 therefore depends on the domain and context in which it is encountered.