This is a list of refrigerants, sorted by their ASHRAE-designated numbers, commonly known as R numbers. Many modern refrigerants are man-made halogenated gases, especially fluorinated gases and chlorinated gases, that are frequently referred to as Freon (a registered trademark of Chemours). The R number of a chemical refrigerant is assigned systematically according to molecular structure. First ASHRAE digit is the number of carbon atoms minus 1 (C-1); the second digit is the number of hydrogen atoms plus 1 (H+1); the third digit is the number of fluorine atoms; any remaining spaces are chlorine atoms. Eg.: R-22 aka R-022, which is chlorodifluoromethane. C=1 i.e. 1-1=0; H=1 i.e. 1+1=2; F=2 i.e 2; 1 remaining space 1=Cl. A "B" number means that one of the chlorine atoms is replaced by bromine (Br). This formula does not work with zeotropic or azeotropic blends. The table is sortable by each of the following refrigerant properties (scroll right or reduce magnification to view more properties): Type/prefix (see legends) ASHRAE number IUPAC chemical name molecular formula CAS registry number / blend name Atmospheric lifetime in years Semi-empirical ozone depletion potential Net global warming potential over a 100-year time horizon Occupational exposure limit/permissible exposure limit in parts per million (volume per volume) over a time-weighted average (TWA) concentration for a normal eight-hour work day and a 40-hour work week ASHRAE 34 safety group in toxicity & flammability (in air @ 60 °C, 101.3 kPa) classing (see legends) Refrigerant concentration limit / immediately dangerous to life or health in parts per million (volume per volume) and grams per cubic meter Molecular mass in atomic mass units Normal boiling point (or bubble & dew points for the zeotrope(400)-series), or normal boiling point and azeotropic temperature for the azeotrope(500)-series) at 101,325 Pa (1 atmosphere) in degrees Celsius Critical temperature in degrees Celsius Absolute critical pressure in kilopascals Since over 100,000 refrigerant blends are possible, this list should only have notable refrigerants and refrigerant blends. List Type and flammability Compounds used as refrigerants may be described using either the appropriate prefix above or with the prefixes "R-" or "Refrigerant." Thus, CFC-12 may also be written as R-12 or Refrigerant 12.An alkene, olefin, or olefine is an unsaturated compound containing at least one carbon-carbon double bond. Educated Estimates See also Haloalkane References Notes Refrigerants Chemical compounds