ISO 817:2014

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 817
ISO/TC 86/SC 8
Refrigerants — Designation and safety
Secretariat: ANSI
classification
Voting begins on:
2012-09-03
Fluides frigorigènes — Désignation et classification de sécurité
Voting terminates on:
2012-11-03
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/FDIS 817:2012(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2012

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ISO/FDIS 817:2012(E)
Copyright notice
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ISO/FDIS 817:2012(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 non­governmental, 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 third edition cancels and replaces the second edition (ISO 817:2005), which has been technically revised.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 817:2012(E)
Refrigerants — Designation and safety classification
1 Scope
This International Standard provides an unambiguous system for assigning designations to refrigerants.
It also establishes a system for assigning a safety classification to refrigerants based on toxicity and
flammability data and provides a means of determining the refrigerant concentration limit. Tables listing
the refrigerant designations, safety classifications and the refrigerant concentration limits are included.
2  Terms, definitions, abbreviated terms and symbols
2.1  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1.1
acute toxicity
adverse health effect(s) from a single, short­term exposure, as might occur during an accidental release
of refrigerants
2.1.2
acute-toxicity exposure limit
ATEL
maximum recommended refrigerant concentration determined in accordance with this International
Standard and intended to reduce the risks of acute toxicity hazards to humans in the event of a
refrigerant release
2.1.3
anaesthetic effect
impairment of the ability to perceive pain and other sensory stimulation
2.1.4
approximate lethal concentration
ALC
concentration of a refrigerant, that was lethal to even a single test animal but to less than 50 % of the
animals in that group when tested by the same conditions as for an LC test
50
2.1.5
azeotrope
blend composed of two or more refrigerants whose equilibrium vapour and liquid phase compositions
are the same at a given pressure, but may be different at other conditions
2.1.6
blends
mixtures composed of two or more refrigerants
2.1.7
burning velocity
S
u
maximum velocity at which a laminar flame propagates in a normal direction relative to the unburned
gas ahead of it
NOTE This value is expressed in centimetres per second.
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ISO/FDIS 817:2012(E)
2.1.8
central nervous system effect
CNS
treatment-related depression, distraction, stimulation, or other behavioural modification to a degree
that could represent an impairment of the ability to escape
2.1.9
chronic toxicity
adverse health effect(s) from long­term repeated exposures
2.1.10
combustion
exothermal reaction between an oxidant component (combustive) and a reducer (combustible fuel)
2.1.11
compound
substance composed of two or more atoms chemically bonded in definite proportions
2.1.12
critical point
conditions above which distinct liquid and gas phases do not exist
2.1.13
cyclic compound
organic compound whose structure is characterized by a closed ring of atoms
2.1.14
effective concentration 50 %
EC
50
concentration of a refrigerant, that has caused a biological effect to 50 % of exposed animals in a test for
anaesthetic or other effects
NOTE This value is typically a calculated value from experimental data.
2.1.15
elevated temperature flame limit
ETFL
minimum concentration by volume percent of the refrigerant that is capable of propagating a flame
through a homogeneous mixture of the refrigerant and air under test conditions specified in subclause
5.1.2 at 60,0°C and 101,3 kPa
2.1.16
equivalence ratio
fraction of the combustible in the mixture divided by the combustible fraction at the stoichiometric conditions
NOTE 1 Can be written as (combustible fraction) / (combustible fraction) .
st
NOTE 2 Used in the determination of burning velocity.
NOTE 3 Lean mixtures have an equivalence ratio lower than one and rich mixtures have an equivalence ratio
greater than one.
2.1.17
flame
space where combustion takes place, resulting in a temperature increase and light emission
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ISO/FDIS 817:2012(E)
2.1.18
flame propagation
combustion, causing a continuous flame which moves upward and outward from the point of ignition
without help from the point of ignition without help from the ignition source
NOTE Flame propagation as applied in the test method for determining LFL and flammability classification
is specified in B.1.7. Flame propagation as applied in the test method for determining burning velocity is
described in Annex C.
2.1.19
flammable
property of a mixture in which a flame is capable of self-propagating for a certain distance
NOTE 1 In its large sense, it characterizes relatively how easy it is for a chemical substance to be ignited and to
sustain the combustion. In a more restrained manner, as used in the studies related to the ignition and burning
of some products, it designates the capability of a product to burn and sustain a flame reaction under specified
test conditions. A combustible-oxidant mixture is not always flammable but restricted to a continuous range of
compositions or flammability range.
NOTE 2 The related noun is “flammability”.
2.1.20
fractionation
change in composition of a blend by preferential evaporation of the more volatile component(s) or
condensation of the less volatile component(s)
2.1.21
heat of combustion
HOC
heat evolved from a specified reaction of a substance with oxygen as determined in accordance with 5.1.2.5
NOTE The heat of combustion for this International Standard is expressed as a positive value for exothermic
reactions in energy per unit mass (kJ/kg).
2.1.22
isomers
two or more compounds having the same chemical composition with differing molecular configurations
NOTE Isomers will have different properties.
EXAMPLE An example is R­600 (CH CH CH CH ) with a boiling point of 0 °C and R­600a (CH(CH ) CH ) with
3 2 2 3 3 2 3
a boiling point of –12°C. Both of these compounds contain four carbon and 10 hydrogen atoms.
2.1.23
lethal concentration 50 %
LC
50
concentration that is lethal to 50 % of the test animals
2.1.24
lower flammability limit
LFL
minimum concentration of the refrigerant that is capable of propagating a flame through a homogeneous
mixture of the refrigerant and air under test conditions specified in 5.1.2 at 23,0 °C and 101,3 kPa
NOTE The LFL is expressed as refrigerant percentage by volume.
2.1.25
lowest observed adverse effect level
LOAEL
lowest concentration of a refrigerant that has caused any observed adverse effect in one or more test animals
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ISO/FDIS 817:2012(E)
2.1.26
no observed adverse effect level
NOAEL
highest concentration of a refrigerant at which no adverse effect has been observed in any of the exposed
animal population
2.1.27
nominal composition
nominal formulation
bulk manufactured composition of the refrigerant, which includes the gas and liquid phases
NOTE 1 Composition of the refrigerant blends as listed in Tables 6 and 7, column 2
NOTE 2 When a container is 80 % or more liquid filled, the liquid composition may be considered the
nominal composition.
2.1.28
occupational exposure limit
time­weighted average concentration for a normal eight­hour work day and a 40­hour work week to
which nearly all workers can be repeatedly exposed without adverse effect, based on the OSHA PEL,
ACGIH TLV­TWA, AIHA WEEL, MAK or consistent value
2.1.29
olefin
unsaturated chemical compound containing at least one carbon­to­carbon double bond
2.1.30
organic compound, saturated
organic, carbon­containing compound that has only single bonds between carbon atoms
2.1.31
organic compound, unsaturated
organic, carbon­containing compound containing at least one double or triple bond between carbon atoms
2.1.32
oxygen deprivation limit
ODL
concentration of a refrigerant or other gas that results in insufficient oxygen for normal breathing
2.1.33
propagation velocity of flame
velocity at which the flame propagates in the space
NOTE In this test method, it refers to the linear velocity at which the flame travels the tube.
2.1.34
quenching
effect of extinction of the flame as it approaches a surface due to heat conduction losses, absorption of
active chemical species and viscous effects on the surface
2.1.35
refrigerant
fluid used for heat transfer in a 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
2.1.36
refrigerant concentration limit
RCL
maximum refrigerant concentration, in air, determined in accordance with this International Standard
and established to reduce the risks of acute toxicity, asphyxiation, and flammability hazards
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ISO/FDIS 817:2012(E)
2.1.37
relative molar mass
mass numerically equal to the molecular mass expressed in grams per mole, except that it is dimensionless
2.1.38
stoichiometric concentration for combustion
C
st
concentration of a fuel in a fuel–air mixture that contains exactly the necessary quantity of air (21 % O /
2
79 % N by volume) needed for the complete oxidation of all the compounds present
2
2.1.39
threshold limit value-time weighted average
TLV-TWA
time weighted average concentration for a normal eight­hour workday and a 40­hour workweek, to
which nearly all workers may be repeatedly exposed, day after day, without adverse effect
2.1.40
workplace environmental exposure limit
WEEL
occupational exposure limit set by the American Industrial Hygiene Association
2.1.41
worst-case formulation
WCF
composition that results from application of the tolerances to the nominal composition resulting in the
most toxic or the most flammable formulation
NOTE For toxicity this is the composition with the highest concentration of the component(s) in the vapour
or liquid phase for which the exposure limit is less than 400 ppm by volume (see F.6.2). For flammability this is the
most flammable composition (i.e. if not flammable, the composition that most closely approaches the flammable
region; or if flammable, the composition that produces the lowest value for the LFL and for burning velocity the
composition that produces the highest S ).
u
2.1.42
worst-case fractionated formulation
WCFF
composition produced during fractionation of the worst­case formulation that results in the most toxic
or most flammable formulation
NOTE For toxicity this is the composition with the highest concentration of the component(s) in the vapour
or liquid phase for which the exposure limit is less than 400 ppm by volume. For flammability this is the most
flammable composition (i.e. if not flammable, the composition that most closely approaches the flammable
region; or if flammable, the composition that produces the lowest value for the LFL and for burning velocity the
composition that produces the highest S ).
u
2.1.43
zeotrope
blend composed of two or more refrigerants whose equilibrium vapour and liquid phase compositions
are not the same at a given pressure
2.2  Abbreviated terms
ALC approximate lethal concentration
ATEL acute­toxicity exposure limit
CNS central nervous system effect
EC effective concentration 50 %
50
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ISO/FDIS 817:2012(E)
ETFL elevated temperature flame limit
HOC heat of combustion
LC lethal concentration 50 %
50
LFL lower flammability limit
LOAEL lowest observed adverse effect level
NOAEL no observed adverse effect level
ODL oxygen deprivation limit
PEL permissible exposure limit
RCL refrigerant concentration limit
RCL RCL expressed as grams per cubic metre
M
RCL RCL expressed as parts per million by volume
ppm
TCF toxic concentration factor
TLV­TWA threshold limit value­time weighted average
WCF worst­case formulation
WCFF worst­case fractionated formulation
WEEL workplace environmental exposure limit
2.3  Symbols
a mortality indicator for a refrigerant blend
blend
a mortality indicator for component n in a refrigerant blend
n
a cross-sectional area of the flame base
f
A flame surface area
f
b cardiac sensitization indicator for component n in a refrigerant blend
n
b cardiac sensitization indicator of a refrigerant blend
blend
c anaesthetic effect indicator for component n in a refrigerant blend
n
c anaesthetic effect indicator of a refrigerant blend
blend
C toxic concentration factor of a refrigerant blend
blend
C toxic concentration factor for component n
n
C stoichiometric concentration for combustion
st
S flame propagation speed, expressed in centimetres per second
s
S burning velocity, expressed in centimetres per second
u
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ISO/FDIS 817:2012(E)
x mole fraction of component n of a refrigerant blend
n
Φ equivalence ratio at the maximum burning velocity
max
3  Numbering of refrigerants
3.1 An identifying number shall be assigned to each refrigerant. Assigned numbers are shown in
Tables 5, 6 and 7.
3.2 The identifying numbers assigned to the hydrocarbons, halocarbons and ethers 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.
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 determined according to 3.2.1 through 3.2.4 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 with the number 1 assigned to the end carbon with the
greatest number of halogen atoms, and the following carbon atoms are numbered sequentially as they
appear on a straight chain. In the case where both end carbons contain the same number of (but different)
halogen atoms, the number 1 shall be assigned to the end carbon 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 back
bone of the molecule has priority over substituent groups on the molecule.
3.2.8 For cyclic compounds, the letter C is used before the identifying refrigerant numbers.
(e.g. R­C318, PFC­C318).
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/FDIS 817:2012(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) as indicated in Table 1.
Table 1 — Propane isomer appended letters
Isomer Appended letter
CCl a
2
CClF b
CF c
2
CHCl d
CHF 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 R­218, not R218ca. An
3 2 3
example of this system is given in Annex A. Bromine containing propane series isomers are not covered
by the appended letters given in 3.2.11 and Table 2.
3.2.11 In the case of isomers in the propene series, each has the same number, with the isomers
distinguished by two appended lower case letters. The first appended letter designates the one atom
attached to the central carbon atom and shall be x, y, or z for Cl, F, and H, respectively. The second letter
designates the substitution on the terminal methlyene carbon as indicated in Table 2.
Table 2 — Propene isomer appended letters
Isomer Appended letter
CCl a
2
CClF b
CF c
2
CHCl d
CHF e
CH f
2
In the case where stereoisomers can exist, the opposed (Entgegen) isomer will be identified by the suffix
(E) and the same side (Zusammen) isomer will be identified by the suffix (Z).
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 Two­carbon, dimethyl ethers (e.g. R­E125, CHF ­O­CF ) require no suffixes other than those
2 3
specified in 3.2.9, as the presence of the “E” prefix provides an unambiguous description.
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ISO/FDIS 817:2012(E)
3.3.2 For straight chain, three carbon ethers, the carbon atoms shall be numbered with the number
1 assigned to the end carbon with the highest number of halogens, and the following carbon atoms are
numbered sequentially as they appear on a straight chain. In the case where both end carbons contain the
same number of (but different) halogen atoms, the number 1 shall be assigned to the end carbon having
the largest number of bromine, then chlorine, then fluorine and then iodine atoms. For ethers with more
than three carbons, the compound shall be assigned a number in the 600 series, miscellaneous organic
compounds, as described in 3.5.
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 ­O­CHF­CF ).
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 CF ­O­CF ­CF , the suffix letters described in 3.2.9, 3.2.10 and 3.2.11 shall be omitted.
3 2 3
In this cited example, the correct designation shall be R­E218.
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” pre-fixes, 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, as described in 3.2.
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, an
upper case letter (A, B, C, .) is added after the number.
3.4.2 Azeotropes shall be serially assigned an identifying number in the 500 series. In order to
differentiate among the different azeotropes having the same refrigerants but a different composition, an
upper case letter (A, B, C, .) is added after the number.
3.4.3 Blends shall have tolerances specified for individual components. Those tolerances shall be
specified to the nearest 0,1 % mass fraction. The maximum tolerance above or below the nominal shall
not exceed 2,0 % mass fraction. The tolerance above or below the nominal shall not be less than 0,1 %
mass fraction. The difference between the highest and the lowest tolerances shall not exceed one­half of
the nominal component composition.
3.5 Miscellaneous organic compounds shall be assigned numbers in the 600 series in decadal groups,
as outlined in Table 5, in serial order of designation within the groups. For the saturated hydrocarbons
with 4 to 8 carbon atoms, the number assigned shall be 600 plus the number of carbon atoms minus 4. For
example, butane is R­600, pentane is R­601, hexane is R­602, heptane is R­603, and octane is R­604. The
straight chain or “normal” hydrocarbon has no suffix. For isomers of the hydrocarbons with 4 to 8 carbon
atoms, the lower case letters “a”, “b”, “c”, etc., are appended to isomers according to the group(s) attached
to the longest carbon chain as indicated in Table 3. For example, R­601a is assigned for 2­methylbutane
(isopentane) and R­601b would be assigned for 2,2­dimethylpropane (neopentane). Mixed isomers
where the concentration of one isomer is greater than or equal to 4 % shall be assigned a number in the
400 or 500 series.
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ISO/FDIS 817:2012(E)
Table 3 — Miscellaneous organic compound suffixes
Attached groups Suffix
none (straight chain) No suffix
2­methyl­ a
2,2­dimethyl­ b
3­methyl­ c
2,3­dimethyl­ d
3,3­dimethyl­ e
2,4­dimethyl­ f
2,2,3­trimethyl­ g
3­ethyl­ h
4­methyl­ i
2,5­dimethyl­ j
3,4­dimethyl­ k
2,2,4­trimethyl­ l
2,3,3­trimethyl­ m
2,3,4­trimethyl­ n
2,2,3,3­tetramethyl o
3­ethyl­2­methyl­ p
3­ethyl­3­methyl­ q
3.6 Inorganic compounds shall be assigned identifying numbers in the 700 series and 7000 series.
3.6.1 For compounds with relative molar masses less than 100, the number shall be the sum of 700 and
the relative molar mass, rounded to the nearest integer.
3.6.2 For compounds with molar masses equal to or greater than 100, the identifying number shall be
the sum of 7000 and the relative molar mass, rounded to the nearest integer.
3.6.3 When two or more inorganic refrigerants have the same molar masses, upper case letters (i.e. A,
B, C, etc.) shall be added in serial order of designation to distinguish among them starting with the letter
A for the second identified inorganic refrigerant of the given molar mass.
4  Designation prefixes
4.1  General prefixes
The identifying number, as determined by Clause 3, shall be preceded by the letter R or the word
Refrigerant(s) unless composition designating prefixes, as described in 4.2 are being used. There shall
be no space between the letter R or the word Refrigerant and the designation number unless a blank or
dash is used. Examples include: R134a, Refrigerant 134a, R 134a, and R­134a.
4.2  Composition-designating prefixes
For the fluorocarbon and the hydrocarbon families, the identifying number, as determined by Clause 3,
may be prefixed by a letter sequence which designates the elements which constitute the specific
compound. The composition-designating prefix shall consist of the first letter of elements contained
in the compound. The first element listed shall be H for hydrogen if present and the last shall be C for
carbon. The intermediate letters shall represent the halogens listed in the following order: I for iodine,
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ISO/FDIS 817:2012(E)
B for bromine, C for chlorine and F for fluorine. Halogenated compounds that contain hydrogen have
increased deterioration potential before reaching the stratosphere. The compositional designating
prefixes for ethers shall substitute an “E” for “C” (carbon), such that HFE, HCFE, and CFE refer to
hydrofluoroether, hydrochlorofluoroether, and chlorofluoroether, respectively. E in the identifying
number shall be omitted when composition-designating prefixes are used. The composition designating
prefixes for halogenated olefins shall be either CFC, HCFC, or HFC to refer to chlorofluorocarbon,
hydrochlorofluorocarbon, or hydrofluorocarbon, respectively, or with substitution of an O for the carbon
C as CFO, HCFO, or HFO to refer to chlorofluoro-olefin, hyrochlorofluroro-olefin, or hydrofluoro-olefin,
respectively. Halogenated olefins are a subset of halogenated organic [or carbon containing] compounds
having significantly shorter atmospheric lifetimes than their saturated counterparts. In addition, when
a refrigerant compound is fully fluorinated the notation PFC is used. Examples are shown in Table 4.
Table 4 — Examples of composition-designating prefixes
Refrigerant Composition Prefix and designation
Chlorofluorocarbon 12 CCl F CFC­12
2 2
Hydrochlorofluorocarbon 22 CHClF HCFC­22
2
Hydrofluorocarbon 134a CH FCF HFC­134a
2 3
Perfluorocarbon 116 CF3CF PFC­116
3
Hydrocarbon 600a (CH ) CH CH HC­600a
3 2 3
Perfluorocarbon C318 ­(CF ) ­ PFC­C318
2 4
Hydrofluoroether E125 CHF OCF HFE­125
2 3
Hydrofluoro-olefin
...