Freon
Freon is DuPont's trade name for its odorless, colorless, nonflammable, and noncorrosive chlorofluorocarbon and hydrochlorofluorocarbon refrigerants, which are used in air conditioning, refrigeration, and some automatic fire-fighting systems. It is one of a class of chemicals called Haloalkanes; Freon and similar refrigerants have been controversial due to environmental (e.g. ozone depletion) and safety concerns. Inhalation of relatively low concentrations of Freon is unlikely to cause major health problems, but higher concentrations can displace enough oxygen to cause asphyxiation.[1][2]
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History
Freon was initially developed in the early 20th century as an alternative to the toxic gases that were previously used as refrigerants, such as ammonia, chloromethane, and sulfur dioxide. Freon, in this case dichlorodifluoromethane, was invented by Thomas Midgley, Jr. with co-inventor Charles Kettering[3] in 1930.[4] Each Freon product is designated by a number; for instance, Freon-11 is trichlorofluoromethane, while Freon-12 is dichlorodifluoromethane, most commonly used is Freon-113 (1,1,2-Trichloro-1,2,2-trifluoroethane) as a cleaning agent.
DuPont began to phase out its production of Freon CFCs in the 1980s after American federal regulatory agencies banned their use because the some of the chlorine atoms separate to form chlorine gas which, in turn, destroys some of the Earth's atmosphere high altitude ozone layer.[5]. This is important because the high altitude ozone blocks some of the cancer inducing ultraviolet light in sunlight from reaching the surface. DuPont held the Freon patent that was terminated in 1992.
In the 1990s, most uses of Freon chlorofluorocarbons (CFCs) were phased out and increasing Federal taxes, at scheduled and progressively increasing rates over time, were added to the production of CFC refrigerants, taxes well above cost of production, to progressively discourage purchase and promote phase out in favor of more expensive and less efficient but also less ozone depleting alternatives.
The Montreal Protocol on Substances that Deplete the Ozone Layer classifies Freon-11 and Freon-12 as Annex A substances and bans their production and consumption as of 1996.
The interim replacements for CFCs are hydrochlorofluorocarbons (HCFCs), which contain chlorine that depletes stratospheric ozone, but to a much lesser extent than CFCs.[6] Ultimately, hydrofluorocarbons (HFCs) will replace HCFCs with essentially no ozone destruction (although all three groups of halocarbons are powerful greenhouse gases). DuPont began producing hydrofluorocarbons as alternatives to Freon in the 1980s. These included Suva refrigerants and Dymel propellants.[5] Any of these gases that are used as refrigerants are designated by an "R-" number and colloquially known as "Freon", whether they are made by DuPont or another supplier.
On November 8, 2008, 20 people died and 21 were injured when suffocated by Freon Gas (used in fire suppressant system) on board the Russian submarine K-152 Nerpa when the vessel's extinguishing systems unexpectedly activated during trials.
References
- ^ Environment, Health and Safety Online
- ^ Safety Data Sheet
- ^ Inventors accessed December 21, 2007
- ^ Carlisle, Rodney (2004). Scientific American Inventions and Discoveries, p.351. John Wiley & Songs, Inc., New Jersey. ISBN 0471244104.
- ^ a b "1930: Freon", DuPont Heritage accessed June 25, 2008
- ^ "Ozone Layer Depletion", U.S. Environmental Protection Agency accessed June 25, 2008
External links
Related
- Haloalkane, a group of chemical compounds
- R134a, a common haloalkane refrigerant used in most vehicles
- List of refrigerants
- Montreal Protocol