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R-134a

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Subject: Carbon dioxide, Montreal Protocol, Wind tunnel, Ozone depletion, Heat pump, Ocean thermal energy conversion, Difluoromethane, 1,1-Difluoroethane, Coolant, George H. Goble
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R-134a

1,1,1,2-Tetrafluoroethane
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Identifiers
CAS number 811-97-2 YesY
ChemSpider 12577 YesY
UNII DH9E53K1Y8 YesY
EC number 212-377-0
KEGG D05208 YesY
RTECS number KI8842500
Jmol-3D images Image 1
Properties
Molecular formula CH2FCF3 [1]
Molar mass 102.03 g/mol
Appearance Colorless gas
Density 0.00425 g/cm³, gas
Melting point

-103.3°C (169.85 K)

Boiling point

-26.3°C (246.85 K)

Solubility in water 0.15 wt%
Hazards
MSDS External MSDS
S-phrases (S2), S23, S24/25, S51
Main hazards Asphyxiant
NFPA 704
0
1
1
Flash point 250 °C (482 °F)
Related compounds
Related refrigerants Difluoromethane
Pentafluoroethane
Related compounds 2-Chloro-
1,1,1,2-tetrafluoroethane

1,1,1-Trichloroethane
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

1,1,1,2-Tetrafluoroethane, R-134a, Forane 134a, Genetron 134a, Suva 134a or HFC-134a, is a haloalkane refrigerant with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with less ozone depletion potential. It has the formula CH2FCF3 and a boiling point of −26.3 °C (−15.34 °F) at atmospheric pressure. R-134a cylinders are colored light blue.[2]

Uses

1,1,1,2-Tetrafluoroethane is an inert gas used primarily as a "high-temperature" refrigerant for domestic refrigeration and automobile air conditioners. These devices began using 1,1,1,2-tetrafluoroethane in the early 1990s as a replacement for the more environmentally harmful R-12 and retrofit kits are available to convert units that were originally R-12-equipped. Other uses include plastic foam blowing, as a cleaning solvent, a propellant for the delivery of pharmaceuticals (e.g. bronchodilators), wine cork removers, gas dusters and in air driers for removing the moisture from compressed air. 1,1,1,2-Tetrafluoroethane has also been used to cool computers in some overclocking attempts. It is also commonly used as a propellant for airsoft airguns.


1,1,1,2-tetrafluoroethane is also being considered as an organic solvent suitable for extraction of flavor and fragrance compounds, as a possible alternative to other organic solvents and supercritical carbon dioxide.[3][4] It can also be used as a solvent in organic chemistry, both in liquid and supercritical fluid.[5] It is used in the resistive plate chamber particle detectors in the Large Hadron Collider.[6][7] It is also used for other types of particle detectors, e.g. some cryogenic particle detectors.[8] It can be used as an alternative to sulfur hexafluoride in magnesium smelting as a shielding gas.[9]

1,1,1,2-tetrafluoroethane is also being considered as an alternative to sulfur hexafluoride as a dielectric gas.[10] Its arc-quenching properties are poor, but its dielectric properties are fairly good.

An additional use of 1,1,1,2-tetrafluroethane is as a propellant. It is used in this way mainly for gas-powered airsoft guns. The gas is often mixed with a silicon-based lubricant.

Climate change considerations

Recently, 1,1,1,2-tetrafluoroethane has been subject to use restrictions due to its contribution to climate change.[11]

United States

The Society of Automotive Engineers (SAE) has proposed 1,1,1,2-tetrafluoroethane (HFC-134a) to be best replaced by a new fluorochemical refrigerant HFO-1234yf (CF3CF=CH2) in automobile air-conditioning systems.[12] California may also prohibit the sale of canned 1,1,1,2-tetrafluoroethane to individuals to avoid non-professional recharge of air conditioners.[13] A ban has been in place in Wisconsin since October 1994 under ATCP 136 prohibiting sales of container sizes holding less than 15 lbs of 1,1,1,2-tetrafluoroethane, but this restriction applies only when the chemical is intended to be a refrigerant. The ban has been lifted in Wisconsin in 2012.[14] It appears, for example, that it is legal for a person to purchase gas duster containers with any amount of the chemical because in that instance the chemical is neither intended to be a refrigerant [14] nor is HFC-134a included in the § 7671a listing of class I and class II substances.[15]

History

1,1,1,2-Tetrafluoroethane first appeared in the early 1990s as a replacement for dichlorodifluoromethane (R-12), which has ozone depleting properties.[16] 1,1,1,2-Tetrafluoroethane has been atmospherically modeled for its impact on depleting ozone and as a contributor to global warming. Research suggests that over the past 10 years the concentration of 1,1,1,2-tetrafluoroethane has increased significantly in the Earth's atmosphere, with a recent study revealing a doubling in atmospheric concentration between 2001 and 2004.[17] It has insignificant ozone depletion potential (ozone layer), significant global warming potential (100-yr GWP = 1430)[18] and negligible acidification potential (acid rain). Because of its high GWP, 1,1,1,2-tetrafluoroethane has been banned from use in the European Union, starting with cars in 2011 and phasing out completely by 2017.[19]

Safety

Contact of 1,1,1,2-tetrafluoroethane with flames or hot surfaces in excess of 250 °C (482 °F) may cause vapor decomposition and the emission of toxic gases including hydrogen fluoride and carbonyl halides.[20] 1,1,1,2-Tetrafluoroethane itself has an LD50 of 1,500 g/m³ in rats, making it relatively non-toxic, apart from the dangers inherent to inhalant abuse. Its gaseous form is denser than air and will displace air in the lungs. This can result in asphyxiation if excessively inhaled.[21][22] This is what contributes to most deaths by inhalant abuse.

Aerosol cans containing 1,1,1,2-tetrafluoroethane, when inverted, become effective freeze sprays. Under pressure, 1,1,1,2-tetrafluoroethane is compressed into a liquid, which upon vaporization absorbs a significant amount of thermal energy. As a result, it will greatly lower the temperature of any object it contacts as it evaporates. This can result in frostbite when it contacts skin, as well as blindness upon eye contact.

See also

References

External links

  • International Chemical Safety Card 1281
  • European Fluorocarbons Technical Committee (EFCTC)
  • MSDS at Oxford University
  • Concise International Chemical Assessment Document 11, at inchem.org
  • Pressure temperature calculator
  • Wayback Machine (archived September 29, 2003)
  • R134a 2 phase computer cooling
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