Chlorofluorocarbons - CFC's
(CFC), any of several organic compounds composed of carbon, fluorine, chlorine, and hydrogen. CFCs are manufactured under the trade name Freon (q.v.). Developed during the 1930s, CFCs found wide application after World War II. These halogenated hydrocarbons, notably trichlorofluoromethane (CFC-11, or F-11) and dichlorodifluoromethane (CFC-12, or F-12), have been used extensively as aerosol-spray propellants, refrigerants, solvents, and foam-blowing agents. They are well-suited for these and other applications because they are nontoxic and nonflammable and can be readily converted from a liquid to a gas and vice versa.
Their commercial and industrial value notwithstanding, CFCs have been found to pose a serious environmental threat. Studies undertaken by various scientists during the 1970s revealed that CFCs released into the atmosphere accumulate in the stratosphere, where they had a deleterious effect on the ozone layer. Stratospheric ozone shields living organisms on Earth from the harmful effects of the Sun's ultraviolet radiation; even a relatively small decrease in the stratospheric ozone concentration can result in an increased incidence of skin cancer in humans and in genetic damage in many organisms. In the stratosphere the CFC molecules break down by the action of solar ultraviolet radiation and release their constituent chlorine atoms. These then react with the ozone molecules, resulting in their removal. (see also Index: ozone depletion)
Because of a growing concern over stratospheric ozone depletion and its attendant dangers, a ban was imposed on the use of CFCs in aerosol-spray dispensers in the late 1970s by the United States, Canada, and the Scandinavian countries. In 1990, 93 nations agreed to end production of ozone-depleting chemicals by the end of the century, and in 1992 most of those same countries agreed to end their production of CFCs by 1996.
A (trademark), any of several chlorofluorocarbons (CFCs) that are used in commerce and industry. The CFCs are a group of aliphatic organic compounds containing the elements carbon
and fluorine and, in many cases, other halogens (especially chlorine) and hydrogen. The name Freon is a trademark registered by the E.I. du Pont de Nemours & Company. Whe using the term (name) Freon in contracting or purchasing, it should always be noted that the term is a trademark. It is often used without regard to its' domicile as a trademark.
The Freons neither present a fire hazard nor give off a detectable odour in their circulation through refrigerating and air-conditioning systems. The most important members of the group have been dichlorodifluoromethane (Freon 12), trichlorofluoromethane (Freon 11), chlorodifluoromethane
(Freon 22), dichlorotetrafluoroethane (Freon 114), and trichlorotrifluoroethane (Freon 113).