Freon or CFC-12 was used for over thirty years as a refrigerant in air conditioning units both in the home and in vehicles. However, it was found to have an impact on the ozone layer and in 1994 the EPA enacted the "Significant New Alternatives Policy" (SNAP) to find new substitutes for CFC-12. The EPA lists 15 acceptable alternatives from pure carbon dioxide to various mixtures of HCFCs, HFCs and hydrocarbons.
Pure carbon dioxide can be used in refrigeration and air conditioning systems that are refitted for the gas. The EPA designation for carbon dioxide is R-744.
Refrigerant gasses containing hydrocarbons such as butane, isobutane and isopentane have been approved by the EPA. Limits on the amount of hydrocarbons are determined by the potential flammability of the refrigerants. R-426A contains a small percentage of isopentane. Isobutane is formulated in R-406A/GHG, GHG-HP, GHG-X4, Hot Shot/ Kar Kool, GHG-X5 and R-426A. Butane is found in FrigC, FR-12.
HCFCs 22, 124, and 142b are found in many refrigerants. HCFC 22 is a major component of R-406A/GHG, GHG-HP, GHG-X4, Hot Shot/Kar Cool, and GHG-X5. HCFC 124 is found in FRIGC FR-12, GHG-X4, and Hot Shot/Kar Kool. HCFC 142b is found in Free Zone/RB-276, R-406A/GHG, GHG-HP, GHG-X4, Hot Shot/Kar Kool, Freeze 12, GHG-X5, and R-420A.
Acceptable HFC components include HFC 125, 134a, 152a and 227ea. Refrigerants containing HFC 125 include R-426a, a new formulation of RS-24. HFC-134a is found in R-134A, FrigC FR-12, Free Zone/RB-276, Freeze 12, R-420A, and R-426A. HFC 152a is found in R-152A. HFC 227ea is found in GHG-X5.
