Chlorodifluoromethane, also known as refrigerant 22 or HCFC-22, is a refrigerant compound used in polystyrene plastics and polyurethane foam. It poses a risk to the ozone layer and is being phased out globally, with production expected to stop in the US by 2020. The chemical is considered stable and has health risks when inhaled in high concentrations. HCFCs were introduced as a short-term solution to replace CFCs, but their reduced ability to deplete the ozone layer is still considered unacceptable in the long term. The Montreal Protocol aims to phase out chlorodifluoromethane and other ozone-depleting chemicals by 2050.
Chlorodifluoromethane is a chloroform-based chemical produced through the chlorination of methane and is primarily used as a refrigerant compound, as well as in the manufacture of polystyrene plastics and polyurethane foam. Another common term for chlorodifluoromethane is refrigerant 22 (R-22) or hydrochlorofluorocarbon 22 (HCFC-22). Hydrochlorofluorocarbon compounds are intermediate compounds used by developing countries in phasing out chlorofluorocarbons (CFCs), due to their energy efficiency and low toxicity. HCFC compounds still pose some risk for depletion of the earth’s ozone layer and as a greenhouse gas, however, and world production of R-22 is declining as it is replaced by safer refrigerants such as R-134a. In the United States as of 2011, the production of HCFC-22 is expected to be completely stopped in 2020.
The American Chemical Society (ACS) Chemical Abstracts Service (CAS) listing classifies the chemical as chlorodifluoromethane – CAS number 75-45-6, with the chemical formula of CHClF2. It is a colorless gas with many synonyms in industry such as difluorochloromethane and is considered a stable organic compound. It has a low boiling point as a compressed liquid of -41.44° Fahrenheit (-40.8° Celsius) and an even lower melting point as a solid of -230.8° Fahrenheit (-146° Celsius).
Refrigerant chemicals such as CFCs and HCFCs tend to be largely inert and long-lived compounds, which is what allows them to survive for long periods in industrial machinery or in the wild. Once out in the open, they slowly move into the upper atmosphere over the course of a decade or more. When they reach a high enough altitude, ultraviolet radiation from the sun and chemical interaction with the atmosphere breaks them down into greenhouse gases and compounds that deplete the ozone layer.
Even the material safety data sheet or MSDS for chlorodifluoromethane suggests that they pose some health risks. When inhaled in concentrations of 50,000 parts per million or higher, they can affect the central nervous system and create irregular heartbeats and cause death. They also have the potential to cause liver, kidney, and blood damage in high concentrations.
HCFC compounds have been introduced as a short-term solution to replace CFCs. Chemical production of ozone-depleting CFCs peaked globally in 1987-1988, and since the introduction of HCFC compounds at that time, world consumption of CFCs has decreased by 75% since 1996. Despite this, and the fact that HCFCs, such as chlorodifluoromethane, are 98% less ozone depleting than CFCs, their reduced ability to deplete the ozone layer is still considered unacceptable in the long term.
In 1987, an international agreement known as the Montreal Protocol created a timetable for phasing out ozone-depleting chemicals such as chlorodifluoromethane gas. Since R-22 is the most widely used refrigerant in commercial heating and cooling systems in the industrialized world, it is a major undertaking to remove it completely from society. All new refrigeration equipment installed in buildings since 2010 must contain R-410A rather than R-22, and R-134a is used in automotive applications to replace chlorodifluoromethane. The Montreal Protocol has been signed by 196 nations and its provisions for phasing out chlorodifluoromethane are expected to restore the ozone layer to its natural state by 2050.
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