Natural or synthetic compounds capable of changing from gas to liquid and back, refrigerants are used as the heat carrier in cooling circuits. R-22 refrigerant, also known as Freon 22, or HCFC-22, was long the refrigerant of choice for air conditioning and commercial refrigeration.
R-22 is a hydrochlorofluorocarbon (HCFC) refrigerant, which means it contains hydrogen, chlorine, fluorine and carbon. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) classifies it with the name chlorodifluoromethane and formula CHClF2.
Most natural refrigerants are made from two molecules---methane and ethane. These two molecules contain only hydrogen and carbon and are known as pure hydrocarbons. To make R-22, a synthetic refrigerant, some of the hydrogen atoms are removed and replaced by chlorine and fluorine.
The U.S. Environment Protection Agency recognizes that R-22 leakage contributes to ozone depletion, while a byproduct of its manufacture (HFC-23) contributes to global warming. Following the Montreal Protocol of 1987, an international environment agreement, R-22 in new equipment has been banned since the start of 2010.