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According to ASHRAE standard 34, the R-number of a chemical refrigerant is assigned systematically according to its molecular structure and has between two and four digits. If there are carbon -carbon multiple bonds , there are four digits in all: the number of these bonds is the first digit and the number of carbon atoms minus one (C-1) is next.
Dichlorodifluoromethane (R-12) is a colorless gas popularly known by the genericized brand name Freon (as Freon-12). It is a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant .
HC-12a, also called ES-12a, OZ-12a, DURACOOL 12a [1] and Hydrocarbon Blend B, is marketed as a "drop-in" replacement refrigerant for R-12 and other refrigerants. HC-12a is a mixture of hydrocarbons, specifically propane (R-290) and isobutane (R-600a), and is therefore considered nearly non-ozone-depleting. The hydrocarbon blend is compatible ...
Chlorodifluoromethane (R-22 or HCFC-22), a type of Freon. [9] [10] Dichlorodifluoromethane (R-12 or CFC-12), the most commonly used Freon brand refrigerant prior to its ban in many countries in 1996 and total ban in 2010. 1,1,1,2-Tetrafluoroethane (R-134a or HFC-134a), one of the main replacements for the formerly widespread R-12.
Difluoromethane is thus a relatively low-risk choice among HFC refrigerants, most of which have higher GWP and longer persistence when leaks occur. The common refrigerant R-410A is a zeotropic, 50/50-mass-percent mixture of difluoromethane and pentafluoroethane .
The refrigerant was developed by the DuPont/Honeywell company and is more expensive per pound than R-134a. R-1234yf can be found in late-model cars and is not cross-compatible with older R-134a or R-12 systems. Of the three refrigerants, R-1234yf is the best for the environment with the lowest global warming potential number which is about a three.
Trichlorofluoromethane was first widely used as a refrigerant.Because of its high boiling point compared to most refrigerants, it can be used in systems with a low operating pressure, making the mechanical design of such systems less demanding than that of higher-pressure refrigerants R-12 or R-22.
HFCs replaced older chlorofluorocarbons such as R-12 and hydrochlorofluorocarbons such as R-21. [2] HFCs are also used in insulating foams, aerosol propellants, as solvents and for fire protection. They may not harm the ozone layer as much as the compounds they replace, but they still contribute to global warming --- with some like ...