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Freon is a trade name for a group of chlorofluorocarbons used primarily as a refrigerant. The word Freon is a registered trademark belonging to DuPont. Prior to their implication as a major contributor to ozone depletion (and a minor contributor to the greenhouse effect), freons were also used as aerosol propellants and to foam up polymer materials.
Freon was developed as a safer alternative to toxic gases such as, ammonia (NH3), methyl chloride (CH3Cl), and sulfur dioxide (SO2), that were used as refrigerants prior to the discovery of freon. Despite the controversy, R12 works well and is very safe. Its inventor, Thomas Midgley, actually breathed in a lungful and exhaled over a candle to demonstrate its nontoxicity and nonflammability.
Before CFCs were banned by developed nations, a 12 ounce (340 g) can of freon (R12) cost about $1; following the ban the cost of freon rose dramatically. People now go through considerable trouble to recycle freon from existing sources. As of 2002, freon cost about $85 per lb ($187 per kg). Freon is most frequently sold in 12 ounce (340 g) cans and 30 pound (13.6 kg) canisters.
Freon 12 ® (also known as R-12) was a popular refrigerant before it was banned. The chemical formula is CCl2F2 and its proper chemical name is dichlorodifluoromethane. When people refer to freon without specifying a number, it is likely that they mean freon-12.
Suva 134a ® (also known as R-134 or R-134a) is the most common replacement for R-12. Unlike R-12, which is a chlorofluorcarbon, R-134 is a hydrofluorocarbon. The chemical formula is CH2FCF3 and the proper chemical name 1,1,1,2-tetrafluoroethane.
| Freon 41 | fluoromethane |
| R-11 | CFC-11 | trichlorofluoromethane |
| R-12 | CFC-12 | dichlorodifluoromethane |
| R-13 | CFC-13 | chlorotrifluoromethane |
| R-22 | HCFC-22 | chlorodifluoromethane |
| R-23 | HFC-23 | trifluoromethane |
| R-113 | CFC-113 | trichlorotrifluoroethane |
| R-114 | CFC-114 | 1,2-dichloro-1,1,2,2-tetrafluoroethane |
| R-115 | CFC-115 | 1-chloro-1,1,2,2,2-pentafluoroethane |
| R-116 | CFC-116 | hexachloroethane |
| R-134a | HFC-134a | 1,1,1,2-tetrafluoroethane |
| R-227ea | HFC-227ea | 1,1,1,2,3,3,3-heptafluoropropane |
Freon in copper tubing open to the environment can turn into phosgene gas after coming in contact with extreme heat, such as, while brazing or in a fire situation. Phosgene is a substance that was used as a chemical weapon in World War I. Low exposure can cause irritation, but high levels cause fluid to collect in the lungs, possibly resulting in fatality.
See also: Halon
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