The refrigerant naming system is mainly used for fluorinated and chlorinated short alkanes used as refrigerants. In the United States, the standard is specified in ANSI/ASHRAE Standard 34–1992, with additional annual supplements. The specified ANSI/ASHRAE prefixes were FC (fluorocarbon) or R (refrigerant), but today most are prefixed by a more specific classification:
*CFC—list of chlorofluorocarbons
*HCFC—list of hydrochlorofluorocarbons
*HFC—list of hydrofluorocarbons
*FC—list of fluorocarbons
*PFC—list of perfluorocarbons (completely fluorinated)
The decoding system for CFC-01234a is:
*0 = Number of double bonds (omitted if zero)
*1 = Carbon atoms -1 (omitted if zero)
*2 = Hydrogen atoms +1
*3 = Fluorine atoms
*4 = Replaced by Bromine ("B" prefix added)
*a = Letter added to identify isomers, the "normal" isomer in any number has the smallest mass difference on each carbon, and a, b, or c are added as the masses diverge from normal.
Other coding systems are in use as well.