The Ozone Depletion Potential of hydrocarbon refrigerants is zero and the Global Warming Potential relative to carbon dioxide is three for all integration periods twenty years or over. Hydrocarbons replace fluorocarbons like CFCs, HCFCs and HFCs which have high environmental impacts and often poor refrigerant performance. Air, ammonia, carbon dioxide and water have lower direct environmental impacts than hydrocarbons and are equally or more acceptable as replacements for fluorocarbons in suitable applications. Boiling Point For systems operating with given temperatures, as vapour pressure increases the cooling capacity, torque and electric current draw all increase. A satisfactory replacement refrigerant will have a boiling point close to the original refrigerant.
Synthetic hydrocarbons are often more expensive than natural hydrocarbons.
Those below are used as replacement refrigerants only when a pure chemical with their boiling point is essential to the system design. The values in square brackets are the percentage composition by mass of the respective refrigerant in the mixture and are omitted where no confusion will occur. Always charge zeotropic refrigerant mixtures as liquids. In redesigned small equipment, R12 and 134a are often replaced by 600a, thinner metal and compressors with higher dimensionless specific speed. The dimensionless specific speed of the compressor is then much closer to one giving higher efficiency.