given the number: first add 90 to the abc number, to obtain a 3-digit definite number (def), where:
d is the number of carbon atoms;
e is the number of hydrogen atoms;
f is the number of fluorine atoms; and
2d + 2 - e - f = the number of chlorine atoms.
For CFC-11: 90 + 11 = 101, so the number of carbon atoms is 1, the number of hydrogen atoms is zero, the number of fluorine atoms is 1, and the number of chlorine atoms is (2 + 2 - 0 - 1 = 3). So the chemical formula for CFC-11 is CFCl3. That is, it has 1 carbon atom, no hydrogen, 1 fluorine atom, and 3 chlorine atoms.
| Similarly: | CFC-12: 12 + 90 = 102; 4-2 = 2 Cl; the chemical formula is: CCl2F2 CFC-113: 113 + 90 = 203; 6-3 = 3 Cl; the chemical formula is: C2Cl3F3 HCFC-142b: 142 + 90 = 232; 6-5 = 1 Cl; the chemical formula is: C2H3F2Cl |
Halons are fluorocarbons with at least one bromine atom.
Halon (no hydrogen number) nomenclature is relatively simple; each halon has an abcd number, where:
a = the number of carbon atoms;
b = the number of fluorine atoms;
c = the number of chlorine atoms, and
d = the number of bromine atoms.
C2F4Br2 is Halon 2402. And, an example going the other way Halon 1211 is CF2ClBr. It is not possible to speak about fluorocarbons without bringing up the issue of the effect of these compounds on the Earth’s Ozone Layer and the Montreal Protocol (described later in this section) that has banned most or all of those fluorocarbons. Examples of the three main commercial classes, based on their interaction with ozone, of fluorocarbons are summarized in Table 2.2. CFC’s have been completely phased out and the others, except for HFOs, are in various stages of being phased out.
Hydrofluorocarbons and, to a very limited extent, perfluorocarbons (PFCs), serve as alternatives to ozone depleting substances phased out under the Montreal Protocol. Tables 2.3 and 2.4 summarize HCFC, HFCs and PFCs fluorocarbons. Applications of HFCs are presented in Table 2.5.
The usage of olefinic fluorocarbons required an extension of the designation system by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). The following descriptions have been adopted from an ASHRAE publication [10].
Olefin: an organic (carbon containing) compound characterized by the presence of one or more double bonds between carbon atoms in the molecule. Such a compound can also be described as being unsaturated.
Unsaturated: as used in this standard, an organic (carbon containing) compound in which one or more carbon atom is joined to other carbon atoms by a carbon-carbon double bond. Such a compound can also be described as an olefin.
The identifying numbers assigned to the hydrocarbons and halocarbons of the methane, ethane, ethene, propane, propene, and cyclobutane series are such that the chemical composition of the compounds can be explicitly determined from the refrigerant numbers, and vice versa, without ambiguity. The molecular structure can be similarly determined for the methane, ethane, ethene, and most of the propane and propene series from only the identification number.
The carbon atoms are numbered sequentially, in order of appearance, with the number 1 assigned to the end carbon with the greatest number of hydrogen substituents (i.e., number of halogenated atoms substituted for hydrogen on the alkane end carbon atoms). In the case where both end carbons of a saturated compound contain the same number of (but different) halogen atoms the number 1 shall be assigned to the first end carbon, defined as having the largest number of bromine, then chlorine, then fluorine, and then iodine atoms. If the compound is an olefin, then the end carbon nearest to the double bond will be assigned the number “1”, as the presence of a double bond in the backbone of the molecule has priority over substituent groups on the molecule.
Table 2.2 Examples of main commercial classes of fluorocarbons [7].
| Fluorocarbon type | Description | Applications |
| CFC | Substance that contains chlorine and has strong characteristics of destroying the ozone layer. Examples: CFC-11, 12, 113 etc. | It has been widely used with refrigerant, blowing, solvent, and aerosol propellant, but in accordance with Montreal Protocol, those have been completely banned production and imports by the end of 1995. |
| HCFC | It contains chlorine but it also contains hydrogen, therefore propensity to destroy the ozone layer is considerably weakened (low ODP).Examples: HCFC-22, 123, 141b, 142b etc. | It has been widely used with refrigerant, blowing, solvent, and aerosol propellant, but in accordance with Montreal Protocol, those are on the way of total abolition. Depending on types and uses, some have been totally abolished. (Example, HCFC-141b for PU blowing agent) |
| HFC | It does not contain chlorine and has hydrogen that does not destroy ozone layer. Examples: HFC-23, 32, 125, 134a, 143a, 152a etc.HFC blend refrigerants R-410A, 407C, 404A. | Refrigerant: Refrigerator, various refrigeration equipment, mobile airconditioning, room air-conditioner, package air-conditioner etc. Blowing agent, solvent, and aerosol propellant. |
| HFO | It does not contain chlorine and has hydrogen. Does not destroy ozone layer. Plus it has no impact on global warming Examples: R-1234yf (CF3CF=CH2), R-1234ze (CF3CH=CHF). | Refrigerator, various refrigeration equipment, mobile air-conditioning, room air-conditioner, package airconditioner etc. Blowing agent, solvent, and aerosol propellant. |
In the case of isomers of propene series, each has the same number, with the isomers distinguished by two appended lowercase letters. The first appended letter indicates the substitution on the central carbon atom:
| - Cl | x |
| - F | y |
| - H | z |
Table 2.3 List of hydrochlorofluorocarbon (HCFC) refrigerants [8].
| Product R-Number | ODP | GWP | |
| 22 | 0,055 | Medium | 1810 |
| 123 | 0,060 | Medium | 77 |
| 401A | 0,033 | ||
