Information AboutRefrigerant |
| CATEGORIES ABOUT REFRIGERANT | |
| hvac | |
| refrigerants | |
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The ideal refrigerant has good Thermodynamic properties, is noncorrosive, and safe. The desired thermodynamic properties are a Boiling Point somewhat below the target temperature, a high Heat Of Vaporization , a moderate Density in liquid form, and a relatively high density in gaseous form. Since boiling point and gas density are affected by Pressure , refrigerants may be made more suitable for a particular application by choice of operating pressure. Corrosion properties are a matter of materials compatibility with the components used for the Compressor , Piping , Evaporator , and Condenser . Safety considerations include Toxicity and Flammability . Early mechanical refrigeration systems employed Sulfur Dioxide gas or Anhydrous Ammonia , with small home refrigerators primarily using the former. Being toxic, sulfur dioxide rapidly disappeared from the market with the introduction of Freon . Ammonia is still used in some large commercial plants, well away from residential areas, where a leak will not cause widespread injuries. Until concerns about depletion of the Ozone Layer arose in the 1980s, the most widely used refrigerants were the Halomethane s R-12 and R-22 , with R-12 being more common in automotive air conditioning and small refrigerators, and R-22 being used for residential and light commercial air conditioning, refrigerators, and freezers. Some very early systems used R-11 because its low boiling point allows low-pressure systems to be constructed, reducing the mechanical strength required for components. R-134a and certain blends are now replacing chlorinated compounds. Use of Liquified Propane Gas as a refrigerant is gaining favor, especially in systems designed for R-12, R-22 or R-134a. NUMBERING The R-# numbering system was developed by DuPont and systematically identifies the molecular structure of refrigerants made with a single halogenated hydrocarbon. The meaning of the codes is as follows:
For example, R-134a has 4 fluorine atoms, 2 hydrogen atoms, 2 carbon atoms, with an empirical formula of tetrafluoroethane. The "a" suffix indicates that the isomer is unbalanced by one atom, giving 1,1,1,2-Tetrafluoroethane . R-134 without the "a" suffix would have a molecular structure of 1,1,2,2-Tetrafluoroethane -- a compound not especially effective as a refrigerant. The same numbers are used with an R- prefix for generic refrigerants, with a "Propellant" prefix (e.g. "Propellant 12") for the same chemical used as a propellant for an Aerosol Spray , and with trade names for the compounds, such as "Freon 12." Recently, a practice of using HFC- for Hydrofluorocarbon s, CFC- for Chlorofluorocarbon s, and HCFC- for Hydrochlorofluorocarbon s has arisen, due to the regulatory differences among these groups. |
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