ISO 817:2005
(Main)Refrigerants — Designation system
Refrigerants — Designation system
ISO 817:2005 provides an unambiguous system for numbering and assigning composition-designating prefixes to refrigerants. Tables listing the refrigerant designations are included. It is intended to be used with other relevant safety standards such as ISO 5149, IEC 603352-24 and IEC 60335-2-40.
Fluides frigorigènes — Système de désignation
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INTERNATIONAL ISO
STANDARD 817
Second edition
2005-01-15
Refrigerants — Designation system
Fluides frigorigènes — Système de désignation
Reference number
ISO 817:2005(E)
©
ISO 2005
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ISO 817:2005(E)
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ii © ISO 2005 – All rights reserved
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ISO 817:2005(E)
Contents Page
Foreword. iv
1 Scope. 1
2 Terms and definitions. 1
3 Numbering of refrigerants. 2
4 Designation prefixes. 4
4.1 General prefixes. 4
4.2 Composition-designating prefixes. 4
5 Refrigerant and refrigerant blend designations. 5
Annex A (informative) Isomer designation examples. 9
Bibliography . 10
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ISO 817:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 817 was prepared by Technical Committee ISO/TC 86, Refrigeration and air-conditioning, Subcommittee
SC 8, Refrigerants and refrigeration lubricants.
This second edition cancels and replaces the first edition (ISO 817:1974), which has been technically revised.
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INTERNATIONAL STANDARD ISO 817:2005(E)
Refrigerants — Designation system
1 Scope
This International Standard provides an unambiguous system for numbering and assigning
composition-designating prefixes to refrigerants. Tables listing the refrigerant designations are included. It is
intended to be used with other relevant safety standards such as ISO 5149, IEC 60335-2-24 and
IEC 60335-2-40.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
azeotrope
blend composed of two or more refrigerants whose equilibrium vapor and liquid phase compositions are the
same at a given pressure, but may be different at other conditions
2.2
blends
mixtures composed of two or more refrigerants
2.3
compound
substance composed of two or more atoms chemically bonded in definite proportions
2.4
cyclic compound
organic compound whose structure is characterized by a closed ring of atoms
2.5
isomers
two or more compounds having the same chemical composition with differing molecular configurations
NOTE Isomers will have different physical properties.
EXAMPLE R-600 (CH CH CH CH ), with a boiling point of 0 °C and R-600a (CH(CH ) CH ) with a boiling point of
3 2 2 3 3 2 3
−12 °C. Both of these compounds contain 4 carbon and 10 hydrogen atoms.
2.6
nominal composition
liquid phase composition of refrigerant blends
NOTE For the refrigerant blends, see Tables 2 and 3.
2.7
refrigerant
fluid used for heat transfer in a mechanical refrigerating system, which absorbs heat at a low temperature and
a low pressure of the fluid and rejects it at a higher temperature and a higher pressure of the fluid, usually
involving changes of the phase of the fluid
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ISO 817:2005(E)
2.8
relative molar mass
mass numerically equal to the molecular mass expressed in grams per mol, except that it is dimensionless
2.9
unsaturated organic compound
organic (carbon-containing) compound containing at least one double or triple bond between carbon atoms
2.10
saturated organic compound
organic (carbon-containing) compound that has only single bonds between carbon atoms
2.11
zeotrope
blend composed of two or more refrigerants whose equilibrium vapour and liquid phase compositions are not
the same at any point
3 Numbering of refrigerants
3.1 An identifying number of 2 to 4 digits shall be assigned to each refrigerant, as follows.
3.2 The identifying numbers assigned to the hydrocarbons, halocarbons and ethers of the methane, ethane,
propane, 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, and most of the propane series.
3.2.1 The first digit on the right is the number of fluorine (F) atoms in the compound.
3.2.2 The second digit from the right is one more than the number of hydrogen (H) atoms in the compound.
3.2.3 The third digit from the right is one less than the number of carbon (C) atoms in the compound. When
this digit is zero, it is omitted from the number.
3.2.4 The fourth digit from the right is equal to the number of carbon-carbon double bonds in the compound.
When this digit is zero, it is omitted from the number.
3.2.5 In those instances where bromine (Br) or iodine (I) is present, the same rules apply, except that the
upper case letter B or I after the designation for the chlorofluoro compound shows the presence of bromine or
iodine. The number following the letter B or I shows the number of bromine or iodine atoms present.
3.2.6 The number of chlorine (Cl) atoms in the compound is found by subtracting the sum of fluorine (F),
bromine (Br), Iodine (I) and hydrogen (H) atoms from the total number of atoms that can be connected to the
carbon (C) atoms. For saturated organic compounds, this number is 2n + 2, where n is the number of carbon
atoms. The number is 2n for compounds with one double bond and saturated cyclic compounds.
3.2.7 The carbon atoms shall be numbered sequentially, in order of appearance, with the number 1
assigned to the end carbon with the greatest number of hydrogen substituents. In the case where both end
carbons 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.
3.2.8 For cyclic compounds, the letter C is used before the identifying refrigerant numbers.
EXAMPLE R-C318, PFC-C318.
3.2.9 In the case of isomers in the ethane series, each has the same number, with the most symmetrical
one indicated by the number alone. As the isomers become more and more unsymmetrical, successive lower
case letters (i.e., a, b, or c) are appended. Symmetry is determined by first summing the atomic mass of the
halogen and hydrogen atoms attached to each carbon atom. One sum is subtracted from the other; the
smaller the absolute value of the difference, the more symmetrical the isomer.
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ISO 817:2005(E)
3.2.10 In the case of isomers in the propane series, each has the same number, with the isomers
distinguished by two appended lower case letters. The first appended letter indicates the substitution on the
central carbon atom (C2):
-CCl- a
2
-CClF- b
-CF - c
2
-CClH- d
-CFH- e
-CH- f
2
For halogenated derivatives of cyclopropane, the carbon atom with the largest sum of attached atomic
masses shall be considered the central carbon atom; for these compounds, the first appended letter is omitted.
The second appended letter indicates the relative symmetry of the substituents on the end carbon atoms (C1
and C3). Symmetry is determined by first summing the atomic masses of the halogen and hydrogen atoms
attached to the C1 and C3 carbon atoms. One sum is subtracted from the other; the smaller the absolute
value of this difference, the more symmetrical the isomer. In contrast to the ethane series, however, the most
symmetrical isomer has a second appended letter of “a” (as opposed to no appended letter for ethane
isomers); increasingly asymmetrical isomers are assigned successive letters. Appended letters are omitted
when no isomers are possible, and the number alone represents the molecular structure unequivocally; for
example, CF CF CF is designated R-218, not R218ca. An example of this system is given in Annex A.
3 2 3
Bromine containing propane series isomers are not covered by the appended letters tabulated above because
no such refrigerants have been identified.
3.3 Ether-based refrigerants shall be designated with the prefix “E” (for “ethers”) immediately preceding the
number. Except for the following differences, the basic number designations for the hydrocarbon atoms shall
be determined according to the current standard for hydrocarbon nomenclature (see 3.2).
3.3.1 Two-carbon, dimethyl ethers (e.g. R-E125, CHF -0-CF ) require no suffixes other than those specified
2 3
in 3.2.9, as the presence of the “E” prefix provides an unambiguous description.
3.3.2 For straight-chain, three carbon ethers, the carbon atoms shall be numbered sequentially, in order of
appearance, with the number 1 assigned to the end carbon with the highest number of halogens. In the case
where both end carbons 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.
3.3.2.1 An additional integer identifying the first carbon to which the ether oxygen is attached shall be
appended to the suffix letters (e.g. R-E236ea2, CHF -O-CHF-CF ).
2 3
3.3.2.2 In the case of otherwise symmetric hydrocarbon structures, the ether oxygen shall be assigned to
the carbon which has the leading position in the formula.
3.3.2.3 In those cases where only a single isomer exists for the hydrocarbon portion of the ether structure,
such as CF3-O-CF2-CF3, the suffix letters described in 3.2.9 shall be omitted. In this cited example, the
correct designation shall be R-E218.
3.3.2.4 Structures containing two oxygen atoms, di-ethers, shall be designated with two suffix integers to
designate the positions of the ether oxygen atoms.
3.3.3 For cyclic ethers carrying both the “C” and “E” prefixes, the “C” shall precede the “E,” as “CE,” to
designate “cyclic ethers.” For four-membered cyclic ethers, including three carbon and one ether oxygen atom,
the basic number designations for the hydrocarbon atoms shall be constructed according to the current
standard for hydrocarbon nomenclature (subsection 3.2).
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ISO 817:2005(E)
3.4 Blends are assigned a refrigerant number in the 400 or 500 series.
3.4.1 Zeotropes shall be serially assigned an identifying number in the 400 series. In order to differentiate
among the different zeotropes having the same refrigerants but a different composition, a capital letter (A, B,
C.) is added after the number.
3.4.2 Azeotropes shall be serially
...
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