A idealistic refrigerant has dependable thermodynamic properties, is noncorrosive, and safe. the desired thermodynamical properties come a boiling point somewhat below the target temperature, a high heat of vaporization, a moderate density inside liquid form, and the comparatively high density in gasous form. Since boiling point & flatulence density come affected by pressure, refrigerants may be processed further suitable for the particular application on purpose of operating pressure.

Corrosion properties come a matter of materials compatibility by using the components utilized for the compressor, piping, evaporator, and condenser. Saftey considerations include toxicity and flammability.

Until concerns just about depletion of the ozone layer arose in a 1980s, a virtually all widely utilized refrigerants were the halomethanes R-12 and R-22, with R-12 existence other commons around self-propelled air conditioner & little icebox, & R-22 existence utilized for residential & lightly commercial air conditioner, icebox, & deep freezer. A select few super early systems utilized R-11 because its online boiling point allows low-pressure systems to become constructed, reducing a mechanical nature and severity expected for components. R-134a and certain blends are nowadays replacing chlorinated compounds.

Numbering

A R-# enumeration technique was developed by DuPont and systematically identifies a molecular structure of refrigerants mass produced by having one halogenated hydrocarbon. A meaning of the codes is when follows:

Rightmost digit - Total of atomic number 9 atoms per molecule. Tens digit - 1 + a total of hydrogen atoms per molecule. 100s digit - A total of carbon atoms minus one. Omitted for methyl group halides, which own simply of these carbon atom. Hundreds to thousands digit - Total of double bonds in the molecule. This is omitted while zero, & inside practice is seldom utilized, since virtually all candidate compounds come unstable. The postfix using the capital B & a total indicates the total of bromine atoms, when present. This is seldom utilized. Remaining bonds non accounted for come occupied by chlorine atoms. The postfix of the lower-pack letter the, b, or even c indicates more and more imbalanced isomers. As a favorite instance, a R-400 series is processed higher of zeotropic blends (victims inside which a boiling point of constitutive compounds differs plenty to lead to changes in relative concentration due to fractional distillation) and a R-500 series is manufactured higher of then-supposed azeotropic blends. A rightmost digit is assigned indiscriminately by ASHRAE, an industry organization.

For instance, R-134a has 4 f atoms, Two hydrogen atoms, Deuce carbon atoms, sustaining an emperical formula of tetrafluoroethane. A "a" postfix indicates that a isomer is unbalanced by of these atom, returning 1,1,1,2-Tetrafluoroethane. R-134 forgoing the "a" postfix would have the molecular structure of 1,1,2,2-Tetrafluoroethane -- a compound non especially efficacious as a refrigerant.

the equivalent amounts come utilized by having an R- prefix for generic refrigerants, sustaining a "Propellant" prefix (e.g. "Propellant 12") for the equivalent chemical substance utilized as a propellent for an aerosol spray, and using brand name for the compounds, like "Freon 12." Recently, the practice of applying HFC- for hydrofluorocarbons, CFC- for chlorofluorocarbons, and HCFC- for hydrochlorofluorocarbons has arisen, due to the regulatory differences among these groups.