Alternatives to HCFCs in the Refrigeration and Air Conditioning Sector 72 app endix I C ommon substances with R numbers The following numbering is based on the standard ISO 817:2003 (also ASHRAE Standard 34). The lists do not Appendix I List of refrigerants Refrfrigerarant number C omposition designating prprefix Ch emical name Ch emical formula M olecular mass (g/mole) N ormal boiling pointa (°C) OD P GWGW P(100 Year) IPCCCC 1996 Ethane series R -170 HC ethane CH3CH3 30.0 −89 0 3 Propane series R -290 HC Propane CH3CH2CH3 44.0 −42 0 3 Unsaturated organic compound in propane series R -1270 HC propene (propylene) CH3CH = CH2 42.1 −48 0 0 Butane series R -600 HC n-Butane CH3CH2CH2CH3 30.0 −89 0 3 R -600a HC Isobutane (CH3)2CH2CH3 30.0 −89 0 3 Inorganic compounds R -717 ammonia NH3 17.0 −33 0 0 R -723 ammonia/ dimethyl ether* NH3/DME 23 -26 0 8 R -744 carbon dioxide CO2 44.0 −78 0 1 *a mixture of inorganic and organic compounds L ow-GWGWP “natural” refrigerantsinclude all refrigerants, but aim to reflect those that are commonly used or discussed as replacements to HCFCs in the RAC sector. common substances with r numbers Red indicate ODS that will be phased out. green indicate alternatives with neglectable environmental impact (can be flammable or toxic). b lue indicates substances with zero ODP that are most common alternatives in the RAC sector today. Wh ite are non-ODS which are mainly used as a components in blends or blends that have limited market presence at this time.