ISO 19703:2018
(Main)Generation and analysis of toxic gases in fire — Calculation of species yields, equivalence ratios and combustion efficiency in experimental fires
Generation and analysis of toxic gases in fire — Calculation of species yields, equivalence ratios and combustion efficiency in experimental fires
This document provides definitions and equations for the calculation of toxic product yields and the fire conditions under which they have been derived in terms of equivalence ratio and combustion efficiency. Sample calculations for practical cases are provided. The methods are intended to be used to produce either instantaneous or averaged values for those experimental fires in which time-resolved data are available. This document is intended to provide guidance to fire researchers for — recording appropriate experimental fire data, — calculating average yields of gases and smoke in fire effluents in fire tests and fire-like combustion in reduced scale apparatus, — characterizing burning behaviour in experimental fires in terms of equivalence ratio and combustion efficiency using oxygen consumption and product generation data. This document does not provide guidance on the operating procedure of any particular piece of apparatus or interpretation of data obtained therein (e.g. toxicological significance of results).
Production et analyse des gaz toxiques dans le feu — Calcul des taux de production des espèces, des rapports d'équivalence et de l'efficacité de combustion dans les feux expérimentaux
Le présent document donne des définitions et des équations permettant de calculer les taux de production en produits toxiques et les conditions de combustion dans lesquelles ces taux de production ont été déterminés en termes de rapport d'équivalence et d'efficacité de combustion. Des exemples pratiques de calculs sur éprouvettes sont également fournis. Les méthodes exposées sont destinées à être utilisées pour produire des valeurs instantanées ou moyennes pour les feux expérimentaux dans lesquels des données en fonction du temps sont disponibles. Le présent document a pour but de fournir des lignes directrices aux chercheurs du domaine de la lutte contre l'incendie, afin: — d'enregistrer des données appropriées relatives aux feux expérimentaux; — de calculer les taux de production moyens en gaz et en fumée dans les effluents pendant les essais au feu et dans des conditions de combustion analogues à celles d'un incendie sur un appareillage à échelle réduite; et — de caractériser les conditions de combustion dans les feux expérimentaux en termes de rapport d'équivalence et d'efficacité de combustion, en utilisant les caractéristiques de consommation d'oxygène et de génération de produits. Le présent document ne fournit aucune ligne directrice sur le mode opératoire d'un appareil spécifique ou sur l'interprétation des données acquises (interprétation toxicologique des résultats, par exemple).
General Information
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 19703
Third edition
2018-06
Generation and analysis of toxic gases
in fire — Calculation of species yields,
equivalence ratios and combustion
efficiency in experimental fires
Production et analyse des gaz toxiques dans le feu — Calcul des taux
de production des espèces, des rapports d'équivalence et de l'efficacité
de combustion dans les feux expérimentaux
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2018 – All rights reserved
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units . 3
5 Appropriate input data required for calculations . 4
5.1 Data handling . 4
5.1.1 Uncertainty . 4
5.1.2 Significant figures and rounding off . 5
5.2 Test specimen information . 5
5.2.1 Composition . 5
5.2.2 Net heat of combustion . 5
5.3 Fire conditions . 5
5.3.1 Apparatus . 5
5.3.2 Set-up procedure . 5
5.4 Data collection . 6
5.4.1 Data acquisition . 6
5.4.2 Measured data and observations . 6
6 Calculation of yields of fire gases and smoke, stoichiometric oxygen-to-fuel mass
ratio and recovery of key elements . 6
6.1 Calculation of measured yields from fire gas concentration data . 6
6.2 Calculation of notional gas yields . 9
6.2.1 General. 9
6.2.2 From the elemental composition . 9
6.2.3 From the empirical formula .10
6.3 Calculation of recovery of elements in key products .11
6.4 Calculation of stoichiometric oxygen-to-fuel mass ratio .11
6.4.1 General.11
6.4.2 From the chemical equation for complete combustion . .11
6.4.3 From the net heat of combustion, ΔH .
c 13
6.4.4 From the carbon content of the material .14
6.5 Calculation of smoke yields .19
6.5.1 General.19
6.5.2 Smoke yields based on mass of smoke particulates .19
6.5.3 Smoke yields based on light obscuring properties .19
6.5.4 Relationship between mass measurement and light obscuration .21
7 Calculation of equivalence ratio .21
7.1 General .21
7.2 Derivation of ϕ for flow-through, steady-state experimental systems .23
7.3 Derivation of ϕ for flow-through, calorimeter experimental systems .24
7.4 Derivation of ϕ for closed chamber systems .24
7.5 Derivation of ϕ in room fire tests .25
8 Calculation of combustion efficiency .25
8.1 General .25
8.2 Heat release efficiency .26
8.3 Oxygen consumption efficiency .26
8.3.1 General.26
8.3.2 Oxygen depletion method .26
8.3.3 Oxygen-in-products method .27
8.4 Oxides of carbon method .28
Bibliography .33
iv © ISO 2018 – All rights reserved
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 3, Fire
threat to people and environment.
This third edition cancels and replaces the second edition (ISO 19703:2010), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— redundant symbols have been deleted;
— missing symbols have been added;
— units of some symbols in formulae and tables have been corrected to conform with the ISO/IEC
Directives, Part 2;
— unnecessary formulae have been deleted;
— mistakes in formulae have been corrected.
Introduction
It is the view of committees ISO TC 92/SC 3, ISO TC 92/SC 4, and IEC TC 89 that commercial products
should not be regulated solely on the basis of the toxic potency of the effluent produced when the
product is combusted in a bench-scale test apparatus (physical fire model). Rather, the information that
characterizes the toxic potency of the effluent should be used in a fire risk or hazard assessment that
includes the other factors that contribute to determining the magnitude and impact of the effluent. It is
intended that the characterization of
a) the apparatus used to generate the effluent, and
b) the effluent itself
be in a form usable in such a fire safety assessment.
As described in ISO 13571, the time to incapacitation in a fire is determined by the integrated exposure
of a person to the fire effluent components. The toxic species concentrations depend on both the yields
originally generated and the successive dilution in air. The former are commonly obtained using a
bench-scale apparatus (in which a specimen from a commercial product is burned) or a real-scale fire
test of the commercial product. These yields, expressed as the mass of effluent component per mass
of fuel consumed, are then inserted into a fluid mechanical model which estimates the rate of fuel
consumption, transport and dilution of the effluent throughout the building as the fire evolves.
For the engineering analysis to produce accurate results, it is preferred that the yield data come from an
apparatus that has been demonstrated to produce yields comparable to those produced when the full
product is burned. In addition to depending on the chemical composition, conformation and physical
properties of the test specimen, toxic-product yields are sensitive to the combustion conditions in the
apparatus. Thus, one means of increasing the likelihood that the yields from a bench-scale apparatus are
accurate is to operate it under combustion conditions similar to those expected when the real product
burns. As described in ISO 19706, the important conditions include whether the fuel is flaming or non-
flaming, the degree of flame extension, the fuel/air equivalence ratio and the thermal environment.
Similarly, these parameters should be known for a real-scale fire test.
The yields of toxic gases, the combustion efficiency and the equivalence ratio are likely to be sensitive
to the manner in which the test specimen is sampled from the whole commercial product. There
can be difficulty or alternative ways of obtaining a proper test specimen. That is not the subject of
this document, which presumes that a specimen has been selected for study and characterizes the
combustion conditions and the yields of effluent species for that specimen.
For those experimental fires in which time-resolved data are available, the methods in this document
should be used to produce either instantaneous or averaged values. The application can be influenced
by changes in the chemistry of the test specimen during combustion. For those fire tests limited to
producing time-averaged gas concentrations, the calculated values produced by the methods in this
document are limited to being averages as well. In real fires, combustion conditions, the fuel chemistry
and the composition of fire effluent from many common materials and products vary continuously
during the course of the fire. Thus, how well the average yields obtained using these methods
correspond to the yields in a given real fire has much to do with the stage of the fire, the pace of fire
development and the chemical nature of the materials and products exposed.
This document provides definitions and equations for the calculation of toxic product yields and the fire
conditions under which they have been derived in terms of equivalence ratio and combustion efficiency.
Sample calculations for practical cases are provided.
vi © ISO 2018 – All rights reserved
INTERNATIONAL STANDARD ISO 19703:2018(E)
Generation and analysis of toxic gases in fire — Calculation
of species yields, equivalence ratios and combustion
efficiency in experimental fires
1 Scope
This document provides definitions and equations for the calculation of toxic product yields and the fire
conditions under which they have been derived in terms of equivalence ratio and combustion efficiency.
Sample calculations for practical cases are provided. The methods are intended to be used to produce
either instantaneous or averaged values for those experimental fires in which time-resolved data are
available.
This document is intended to provide guidance to fire researchers for
— recording appropriate experimental fire data,
— calculating average yields of gases and smoke in fire effluents in fire tests and fire-like combustion
in reduced scale apparatus,
— characterizing burning behaviour in experimental fires in terms of equivalence ratio and combustion
efficiency using oxygen consumption and product generation data.
This document does not provide guidance on the operating procedure of any particular piece of
apparatus or interpretation of data obtained therein (e.g. toxicological significance of results).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 13943, Fire safety — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http: //www .electropedia .org/
— ISO Online browsing platform: available at http: //www .iso .org/obp
3.1
mass concentration of gas
mass of gas per unit volume
Note 1 to entry: The mass concentration of a gas shall be derived directly from the measured volume fraction and
its molar mass or measured directly.
Note 2 to entry: Mass concentration is typically expressed in units of grams per cubic metre.
3.2
mass concentration of particles
mass of solid and liquid aerosol particles per unit volume
Note 1 to entry: Mass concentration of particles is typically expressed in units of grams per cubic metre.
3.3
molar mass
mass of 1 mole
Note 1 to entry: Molar mass is normally expressed in units of grams per mole.
3.4
recovery of element
〈in a specified combustion product〉 degree of conversion of an element in the test specimen to a
corresponding gas
Note 1 to entry: It is the ratio of the actual yield to notional yield of the gas containing that element.
3.5
relative atomic mass
average mass of one atom of an element divided by one twelfth of the mass of one atom of carbon
(isotope C)
3.6
stoichiometric oxygen-to-fuel mass ratio
amount of oxygen needed by a material for complete combustion
Note 1 to entry: Stoichiometric oxygen-to-fuel mass ratio is typically expressed in units of grams of oxygen per
gram or kilogram of burnt material.
3.7
uncertainty
uncertainty of measurement
parameter, associated with the result of a measurement, that characterizes the dispersion of the values
that could reasonably be attributed to the measurement
Note 1 to entry: The description and propagation of uncertainty in measurements are described in ISO/
[24]
IEC Guide 98-3 .
[SOURCE: ISO/IEC Guide 98-3:2008, 2.2.3, modified—The term has been changed from “uncertainty (of
measurement)” to “uncertainty”; “uncertainty of measurement” has been added as an admitted term;
the original Notes 1, 2 and 3 to entry have been deleted and a new Note 1 to entry has been added.]
3.8
expanded uncertainty
quantity defining an interval about the result of a measurement that may be expected to encompass a
large fraction of the distribution of values that could reasonably be attributed to the measurement
Note 1 to entry: Adapted from ISO/IEC Guide 98-3:2008, 2.3.5.
2 © ISO 2018 – All rights reserved
4 Symbols and units
Table 1 — Symbols
Symbol Quantity Typical unit
A extinction area of smoke square metre
A or A specific extinction area of smoke per unit mass of material burned square metres per gram
σf SEA
or square metres per
kilogram
D mass optical density (log analogue of A ) square metres per gram
MO 10 SEA
or square metres per
kilogram
F recovery fraction of element E in gas containing E dimensionless
R,E
ΔH measured heat release in a combustion kilojoules per gram
act
ΔH net heat of combustion or enthalpy generated in complete combustion kilojoules per gram
c
I/I fraction of light transmitted through smoke dimensionless
o
L is the length of the light path through the smoke metre
m relative atomic mass of the element E dimensionless
A,E
m mass fraction of element E in the material dimensionless
E
m mass of fuel gram
fuel
m total mass of the gas of interest gram
gas
m total mass loss of material gram
m,loss
material mass loss rate grams per minute
m
m,loss
m actual mass of oxygen available for combustion gram
O,act
actual mass flow of oxygen available for combustion grams per minute
m
O,act
m stoichiometric mass of oxygen required for complete combustion gram
O,stoich
m total mass of particles gram
part
M molar mass of the gas of interest grams per mole
gas
M molar mass of the polymer unit grams per mole
poly
n number of atoms of element E in one molecule of gas dimensionless
E
n number of atoms of element E in the polymer unit dimensionless
E,poly
P ambient pressure kilopascal
amb
P standard pressure 101,3 kPa
std
T thermodynamic temperature of the gas of interest at the point of kelvin
C
measurement
V volume of chamber cubic meter
V total volume of fire effluent cubic metre
eff
volume air flow cubic metres per minute
V
air
w measured mass fraction of oxygen consumed per unit mass of fuel dimensionless
O,cons
w derived mass fraction of oxygen consumed per unit mass of fuel dimensionless
O,der
w mass fraction of oxygen in polymer that contributes to the formation dimensionless
Oex,poly
of oxygen-containing products
w mass fraction of oxygen consumed in the form of the major oxy- dimensionless
O,gases
gen-containing products (w + w + w )
O,CO2 O,CO O,H2O
w mass fraction of oxygen in the polymer dimensionless
O,poly
Y measured mass yield of gas of interest dimensionless
gas
Y measured mass yield of smoke particles dimensionless
part
α linear decadic absorption coefficient (or optical density) inverse metre
Table 1 (continued)
Symbol Quantity Typical unit
α light extinction coefficient inverse metre
k
χ combustion efficiency dimensionless
χ combustion efficiency calculated from the generation efficiency of dimensionless
cox
carbon in the fuel to oxides of carbon
χ combustion efficiency calculated from oxygen depletion dimensionless
O
χ combustion efficiency calculated from the oxygen in the major com- dimensionless
prod
bustion products
ϕ equivalence ratio dimensionless
η generation efficiency for oxides of carbon dimensionless
φ volume fraction of the gas of interest dimensionless
gas
φ volume fraction oxygen in the air supply (0,209 5 for dry air) dimensionless
O
ρ mass concentration of the gas of interest grams per cubic metre
gas
ρ mass loss concentration of the material grams per cubic metre
m,loss
ρ actual mass concentration of oxygen available for combustion grams per cubic metre
O,act
ρ mass concentration of the smoke particles grams per cubic metre
part
σ mass specific extinction coefficient square metres per gram
m,α
or square metres per
kilogram
Ψ notional yield (mass fraction) of gas of interest dimensionless
gas
Ψ stoichiometric oxygen-to-fuel mass ratio dimensionless
O
5 Appropriate input data required for calculations
5.1 Data handling
5.1.1 Uncertainty
In calculating the fire parameters described in this document, the uncertainty or error associated
[1]
with each component shall be taken into account and they shall be combined in the correct manner .
Uncertainty is derived from accuracy (how close the measured value is to the true value) and precision
(how well the values agree with each other). There are uncertainties relating to physically measured
parameters (e.g. mass loss and gas concentrations).
Assuming all errors to be independent, the total error, δq, is obtained by summing the squares of the
errors in accordance with the general Formula (1):
δq δq
δq= δa ++. δz (1)
δa δz
In other words, evaluate the error caused by each of the individual measurements, then combine them
by taking the root of the sum of the squares.
In empirically derived equations, uncertainties in “constant” values shall be treated similarly to
measurement uncertainties. If a constant is truly constant, i.e. has negligible uncertainty, it can be
neglected.
4 © ISO 2018 – All rights reserved
5.1.2 Significant figures and rounding off
When recording and reporting data, significant figures shall be handled properly. The general approach
is to carry one digit beyond the last certain one. When rounding off, the typical rule is to round up when
the figure to be dropped is 5 or more and round down when it is less than 5.
5.2 Test specimen information
5.2.1 Composition
Information shall be given where possible on the combustible fraction, organic and inorganic
combustible components, inert components, elemental composition, empirical formula and molecular
or formula weight.
Where the combustible in a fire experiment is a single, homogenous material, perhaps with dispersed
additives, the molecular formula of the material shall be provided. Commercial products, however,
are generally non-homogeneous combinations of materials, with each component containing one or
more polymers and possibly multiple additives. For complex materials representative of commercial
products, the yields, effective heats of combustion, etc. vary with time as the various components
become involved. For some of the following (global) calculations, a simplification is the use of an
empirical formula for the composite.
5.2.2 Net heat of combustion
The net heat of combustion for combustible components shall be required for some of the calculations
(e.g. combustion efficiency).
5.3 Fire conditions
5.3.1 Apparatus
Give the name of the apparatus with a brief description of mode of operation (e.g. flow-through steady
state, calorimeter and closed chamber system). Refer to the appropriate standard or other reference
relating to the procedure.
5.3.2 Set-up procedure
The fire conditions are generally apparatus-dependent and largely dictated by the set-up procedure for
the particular apparatus. The following information shall be required:
a) test specimen details, its mass, dimensions and orientation of the combustible;
b) thermal environment, in terms of the temperature (expressed in degrees Celsius) and irradiance
(expressed in kilowatts per square metre) to which test specimen is subjected;
NOTE The temperature distribution and the radiation field in a test are frequently not uniform and, as
a result, are rarely well documented. Sufficient information about the thermal and radiative conditions is
intended to allow another person to reproduce the results using the same apparatus, compare the results
with results for the same specimen tested in another apparatus, etc.
c) oxygen concentration in the air supply (volume percent or volume fraction);
d) volume of chamber or air flow. For a closed system, give the air volume (expressed in litres or cubic
metres) and for an open system, give the air flow (expressed in litres per minute or in cubic metres
per minute) and the dynamics of the flow. In both cases, give information on the atmospheric
mixing conditions and the degree of homogeneity of the fire effluent.
5.4 Data collection
5.4.1 Data acquisition
Time-resolved data or time-integrated data may be acquired. The method of data acquisition shall be
specified in the test protocol.
5.4.2 Measured data and observations
Most of the following data parameters shall be used to calculate yields, equivalence ratios and
combustion efficiencies in experimental fires. Usually, the units applied to data should be dictated by
the operational procedure associated with a particular piece of apparatus. The following are a number
of suggested typical units:
a) mass loss of the test specimen, derived by measuring the test specimen mass before and after
test to give overall mass loss (expressed in milligrams, grams or kilograms) or mass loss fraction
(expressed in mass percent, grams per gram or kilograms per kilogram), or by measuring the
specimen mass throughout a test to give mass loss rate (expressed in milligrams per second, grams
per minute or kilograms per minute);
b) gas and vapour concentrations and oxygen depletion (expressed in volume percent, volume
fraction, microlitres per litre, milligrams per litre or milligrams per cubic metre);
c) smoke particulate concentration (expressed in milligrams per litre or milligrams per cubic metre)
and smoke obscuration (expressed in optical density per metre or square metres per kilogram);
d) heat release (expressed in kilojoules per gram), used to calculate combustion efficiency, forms part
of the protocol for some apparatuses;
e) combustion mode, time to ignition (expressed in minutes or seconds) and whether the specimen
flames or not throughout the test.
6 Calculation of yields of fire gases and smoke, stoichiometric oxygen-to-fuel
mass ratio and recovery of key elements
6.1 Calculation of measured yields from fire gas concentration data
In experimental fires, the mass yield, Y , of a gas shall be calculated from the measured mass
gas
concentration of the gas of interest and the mass loss concentration of the material in accordance with
Formula (2) (see NOTES 1, 2 and 3):
ρ
gas
Y = (2)
gas
ρ
m,loss
where
ρ is the mass concentration of the gas;
gas
ρ is the mass loss concentration of the material.
m,loss
Alternatively, Y shall be calculated from the total mass of gas generated and the total mass loss of
gas
material in accordance with Formula (3):
m
gas
Y = (3)
gas
m
m,loss
where
6 © ISO 2018 – All rights reserved
m is the total mass of the gas;
gas
m is the total mass loss of the material.
m,loss
NOTE 1 These calculations can be derived from instantaneous data or from data which assumes that the
gases are uniformly dispersed in a certain volume and that this volume is the same one in which the lost sample
mass is (evenly) dispersed. If the dispersion is not uniform, the equations still work if the lost mass and the gas
in question are dispersed equivalently. If a combustion gas is prone to surface losses within the apparatus, the
apparent yield depends on where the concentration is being measured.
NOTE 2 In flow-through devices, the total effluent is generally well mixed at some distance downstream. For
closed-box combustion systems, it is not necessarily so, especially if there are large molecular weight differences
and large thermal gradients. If multiple fuels are involved, only some averaged combined yield can be calculated.
NOTE 3 In setting up these calculations, uncertainties relating to lost sample mass, fluctuations in the
measured concentration, etc. occur.
The uncertainty shall be monitored. The calculated yield shall take account of and combine these
uncertainties, enabling a sound basis for comparing yields under different combustion conditions,
comparing yields from different materials and so on.
Whilst concentrations of the specific gas are most often measured in volume fractions,
Formulae (4) and (5) show how to convert the volume fraction of a gas to its mass concentration:
M
273,15K P
gas
amb
ρϕ=× ×× (4)
gasgas
31−
T 101,325kPa
22,414dm ⋅mol
C
where
ρ is the mass concentration of the gas;
gas
φ is the volume fraction of the gas;
gas
M is the molar mass of the gas;
gas
T is the thermodynamic temperature of the gas at the point of measurement;
C
P is the ambient pressure;
amb
273,15 K is the standard thermodynamic temperature;
101,325 kPa is the standard pressure;
3 −1
22,414 dm ⋅mol is the molar volume of an ideal gas at standard temperature and pressure.
Thus, for fire effluent at 20 °C and standard pressure, Formula (4) simplifies to Formula (5):
M
gas
ρϕ=× (5)
gasgas
31−
24,055dm ⋅mol
EXAMPLE The calculations for a well-ventilated fire atmosphere where mass loss concentration of the
−3
material is 25 g⋅m and the volume fraction of carbon monoxide (CO) is 0,125% (or 0,001 25) at 20 °C are shown
in Formulae (6) and (7):
−1
28,01gm⋅ ol
−3 −3
ρ =×0,00125 =⋅0,,001456gdm =14556gm⋅ (6)
CO
31−
24,055dm ⋅mol
−−33
Y =⋅1,/456gm 25gm⋅=0,0582 (7)
co
where
ρ is the mass concentration of CO;
CO
Y is the mass yield of CO (mass of CO per unit mass of material);
CO
−1
28,01 g⋅mol is the molar mass of CO.
The relative atomic mass, molar mass and gas concentration conversion factors for the major fire gases
are listed in Tables 2 and 3.
[2]
Table 2 — Relative atomic mass of key fire gas elements
a
Element Symbol Relative atomic mass
Carbon C 12,011
Hydrogen H 1,0079
Oxygen O 15,999
Nitrogen N 14,007
Chlorine Cl 35,453
Bromine Br 79,904
Fluorine F 18,998
Sulfur S 32,065
Phosphorus P 30,973
Antimony Sb 121,76
a
Relative atomic mass values rounded to five significant figures.
Table 3 — Molar masses of common fire gases and volume fraction/mass concentration
conversion factors
Gas or vapour Formula Molar Gas concentration conversion factors
a
mass (at 20 °C and 101,3 kPa)
−1
g·mol
To convert volume fraction to To convert concentration to
concentration, volume fraction,
multiply by density of the gas: divide by density of the gas:
b −3
Carbon dioxide CO 44,01 1 830 g.m
b −3
Carbon monoxide CO 28,01 1 164 g.m
−3
Hydrogen cyanide HCN 27,02 1 124 g.m
−3
Nitrogen dioxide NO 46,01 1 913 g.m
−3
Nitrous oxide N O 44,01 1 831 g.m
−3
Nitric oxide NO 30,01 1 248 g.m
−3
Ammonia NH 17,03 708 g.m
−3
Hydrogen chloride HCl 36,46 1 516 g.m
−3
Hydrogen bromide HBr 80,91 3 364 g.m
−3
Hydrogen fluoride HF 20,01 832 g.m
−3
Hydrogen sulfide H S 34,08 1 417 g.m
−3
Sulfur dioxide SO 64,06 2 663 g.m
NOTE The concentration of a gas equals to volume fraction x density.
Example calculations:
4 −3 −3
If φ = 0,01 (i.e. 1 % or 10 μl/l), m = 0,01 × 1 164 g⋅m =11,64 g⋅m .
CO CO
−3 −3 −3
If m = 0,281 g⋅m , φ =0,281 g⋅m /1 124 g⋅m =0,000 25 (i.e. 0,025 % or 250 μl/l).
HCN HCN
a
Molar mass values are rounded to two decimal places.
b
CO /CO volume ratio equals the CO /CO mass ratio divided by 1,571.
2 2
8 © ISO 2018 – All rights reserved
Table 3 (continued)
Gas or vapour Formula Molar Gas concentration conversion factors
a
mass (at 20 °C and 101,3 kPa)
−1
g·mol
To convert volume fraction to To convert concentration to
concentration, volume fraction,
multiply by density of the gas: divide by density of the gas:
−3
Water H O 18,01 749 g.m
−3
Phosphoric acid H PO 97,99 4 074 g.m
3 4
−3
Acrolein C H O 56,06 2 331 g.m
3 4
−3
Formaldehyde CH O 30,03 1 248 g.m
−3
Oxygen O 32,00 1 331 g.m
NOTE The concentration of a gas equals to volume fraction x density.
Example calculations:
4 −3 −3
If φ = 0,01 (i.e. 1 % or 10 μl/l), m = 0,01 × 1 164 g⋅m =11,64 g⋅m .
CO CO
−3 −3 −3
If m = 0,281 g⋅m , φ =0,281 g⋅m /1 124 g⋅m =0,000 25 (i.e. 0,025 % or 250 μl/l).
HCN HCN
a
Molar mass values are rounded to two decimal places.
b
CO /CO volume ratio equals the CO /CO mass ratio divided by 1,571.
2 2
6.2 Calculation of notional gas yields
6.2.1 General
The notional yields of gases and vapours are a measure of the maximum theoretical combustion
product yields. They are based on the composition of the material and are entirely material-dependent.
Two primary methods for calculating notional yields are described in 6.2.2 and 6.2.3.
6.2.2 From the elemental composition
Provided the elemental composition of the base material is known (e.g. by elemental analysis), the
maximum possible (notional) yield, Ψ , of fire gas corresponding to each specified element, E, is
gas
calculated in accordance with Formula (8):
M
gas
Ψ =×m (8)
gasE
nm×
EA,E
where
m is the mass fraction of element E in the material;
E
M is the molar mass of the gas which is under consideration;
gas
n is the number of atoms of element E in one molecule of the gas;
E
m is the relative atomic mass of the element E.
A,E
EXAMPLE The notional yield, Ψ , of CO from cellulose, (C H O ) , is calculated as given by Formula (9):
CO 6 10 5 n
−1
28,01gm⋅ ol
Ψ =×0,445 =1,038 (9)
CO
−1
11×⋅2,011gmol
where
0,445 is the mass fraction of carbon in the cellulose;
−1
28,01 g⋅mol is the molar mass of CO;
1 is the number of atoms of carbon in one molecule of CO;
−1
12,011 g⋅mol is the molar mass of carbon.
Factors for calculating notional gas yields from the elemental composition and derived from the term
M
gas
in Formula(8), are given in Table 4.
nm×
EA,E
Table 4 — Factors for calculating notional gas yields from the elemental composition of
material
a
Gas or vapour Element E considered in base Factor
material
Formula Molar mass
g⋅mol-1
CO 44,01 carbon 3,664
CO 28,01 carbon 2,332
H O 18,02 hydrogen 8,939
HCN 27,02 nitrogen 1,929
NO 46,01 nitrogen 3,284
N O 44,01 nitrogen 1,571
NO 30,01 nitrogen 2,142
NH 17,03 nitrogen 1,216
HCl 36,46 chlorine 1,028
HBr 80,92 bromine 1,013
HF 20,01 fluorine 1,053
H S 34,08 sulfur 1,063
H PO 97,98 phosphorus 3,163
3 4
SO 64,06 sulfur 1,998
Acrolein (C H O) 56,06 carbon 1,556
3 4
Formaldehyde 30,03 carbon 2,500
(CH O)
M
gas
a
Factor rounded to four significant figures.
nm×
EA,E
6.2.3 From the empirical formula
If the empirical formula of the material is known, the notional yield, Ψ , shall be calculated from
gas
Formula (10):
n M
E,poly gas
Ψ =× (10)
gas
n M
E poly
where
n is the number of atoms of element E in the empirical formula;
E,poly
M is the molar mass of the empirical formula.
poly
10 © ISO 2018 – All rights reserved
EXAMPLE The notional yield, Ψ , of carbon dioxide (CO ) from polypropylene with the empirical formula
CO
(C H ) is calculated as shown in Formula (11):
3 6
−1
3 44,01gm⋅ ol
Ψ =× =3,142 (11)
CO
−1
42,03gm⋅ ol
where
is expressed in grams of CO per gram of polymer;
Ψ
CO
1 is the number of atoms of carbon in one molecule of CO ;
3 is the number of atoms of carbon in the polymer unit;
−1
44,01 g⋅mol is the molar mass of CO ;
−1
42,03 g⋅mol is the molar mass of the polymer unit.
NOTE The notional yield of a gas that contains more than one element from the fuel molecule is determined
by the least prevalent element (other than oxygen). Thus, the notional yield of HCN can be most often determined
by the nitrogen content of the fuel. However, for a product gas like formaldehyde, it can be either the carbon or
hydrogen fraction that provides the criterion, depending on the fuel composition.
6.3 Calculation of recovery of elements in key products
The recovery fraction of an element in a key combustion product (alternatively, the conversion efficiency
of an element in the test specimen to a corresponding gas ) shall be calculated from the measured yield,
Y , of the gas of interest relative to its notional yield, Ψ . For a material containing element E, this
gas gas
corresponds to Formula (12):
η = Y /Ψ (12)
E, gas gas gas
where
Y is derived from Formulae (2) to (7);
gas
Ψ is derived from Formulae (8) to (11);
gas
η is the recovery fraction or conversion efficiency of element E in gas containing E.
E, gas
6.4 Calculation of stoichiometric oxygen-to-fuel mass ratio
6.4.1 General
Stoichiometric oxygen-to-fuel mass ratio is the amount of oxygen needed by a material for complete
combustion. Its derivation is somewhat more complex than notional gas yields and should be calculated
by one of the three primary methods as described in 6.4.2 to 6.4.4.
6.4.2 From the chemical equation for complete combustion
6.4.2.1 For fuels containing C, H, O, for complete combustion to carbon dioxide and water
For the complete combustion of fuels containing C, H, O, the products only consist of CO and gaseous
H O. For organic fuels which contain oxygen, the requirement of oxygen from air for complete
combustion is less than for those which do not contain oxygen. For a polymer with the general formula
C H O , Formulae (13) to (15) apply:
a b c
C H O + zO → aCO + b/2 HO (13)
a b c 2 2 2
and
22ab+ −c
()
z= (14)
where
z is the (stoichiometric) number of moles of O required for complete combustion of one mole of C H O ;
2 a b c
a is the number of atoms of carbon in C H O ;
a b c
b is the number of atoms of hydrogen in C H O ;
a b c
c is the number of atoms of oxygen in C H O .
a b c
The stoichiometric oxygen-to-fuel mass ratio required for complete combustion is then calculated from
Formula (15):
z×32,00
Ψ = (15)
O
M
poly
where
Ψ is the stoichiometric oxygen-to-fuel mass ratio, expressed in grams of oxygen per
O
gram of polymer;
−1
32,00 g⋅mol is the molar mass of oxygen.
EXAMPLE The stoichiometric combustion equation for polymethyl methacrylate (PMMA) is given by
Formulae (16) and (17):
C H O + 1,20 O → CO + 0,80 HO (16)
1,0 1,6 0,4 2 2 2
12,,03× 200
Ψ = =1,918 (17)
O
20,02
where
1,0 is the number of atoms of carbon in C H O ;
1,0 1,6 0,4
1,6 is the number of atoms of hydrogen in C H O ;
1,0 1,6 0,4
0,4 is the number of atoms of oxygen in C H O ;
1,0 1,6 0,4
1,20 is the (stoichiometric) number of moles of O required for complete combustion of one
mole of C H O ;
1,0 1,6 0,4
1,918 is the calculated stoichiometric oxygen-to-fuel mass ratio of PMMA, expressed in grams
of oxygen per gram of PMMA.
12 © ISO 2018 – All rights reserved
6.4.2.2 For fuels containing hetero-elements
For the complete combustion of fuels containing (organically-bound) elements in addition to C, H and O,
it is assumed that nitrogen generates gaseous N , halogens generate gaseous acid gases (HCl, HBr, etc.)
and sulfur generates gaseous SO .
Combustion equations for this type of test material are more complex because, for example, hydrogen
from the material is used to form acid gases as well as water and sulfur consumes oxygen to form
SO . For a halogenated material with the general formula of C H O N Cl Br F S , the equation f
...
ISO/FDIS 19703:2018(E)
ISO/FDIS 19703
2018-03-16
Generation and analysis of toxic gases in fire — Calculation of species yields, equivalence
ratios and combustion efficiency in experimental fires
Production et analyse des gaz toxiques dans le feu -- Calcul des taux de production des
espèces, des rapports d'équivalence et de l'efficacité de combustion dans les feux
expérimentaux
ISO/FDIS 19703:2018(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following
URL: www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 3, Fire
threat to people and environment.
This third edition cancels and replaces the second edition (ISO 19703:2010), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— redundant symbols have been deleted;
— missing symbols have been added;
— units of some symbols in formulae and tables have been corrected to conform with the ISO/IEC
Directives, Part 2;
— unnecessary formulae have been deleted;
— mistakes in formulae have been corrected.
ii © ISO 2018 – All rights reserved
ISO/FDIS 19703:2018(E)
Introduction
It is the view of committees ISO TC 92/SC 3, ISO TC 92/SC 4, and IEC TC 89 that commercial products
shallshould not be regulated solely on the basis of the toxic potency of the effluent produced when the
product is combusted in a bench-scale test apparatus (physical fire model). Rather, the information that
characterizes the toxic potency of the effluent shallshould be used in a fire risk or hazard assessment
that includes the other factors that contribute to determining the magnitude and impact of the effluent.
It is intended that the characterization of
a) the apparatus used to generate the effluent, and
b) the effluent itself
be in a form usable in such a fire safety assessment.
As described in ISO 13571, the time to incapacitation in a fire is determined by the integrated exposure
of a person to the fire effluent components. The toxic species concentrations depend on both the yields
originally generated and the successive dilution in air. The former are commonly obtained using a
bench-scale apparatus (in which a specimen from a commercial product is burned) or a real-scale fire
test of the commercial product. These yields, expressed as the mass of effluent component per mass of
fuel consumed, are then inserted into a fluid mechanical model which estimates the rate of fuel
consumption, transport and dilution of the effluent throughout the building as the fire evolves.
For the engineering analysis to produce accurate results, it is preferred that the yield data come from an
apparatus that has been demonstrated to produce yields comparable to those produced when the full
product is burned. In addition to depending on the chemical composition, conformation and physical
properties of the test specimen, toxic-product yields are sensitive to the combustion conditions in the
apparatus. Thus, one means of increasing the likelihood that the yields from a bench-scale apparatus
are accurate is to operate it under combustion conditions similar to those expected when the real
product burns. As described in ISO 19706, the important conditions include whether the fuel is flaming
or non-flaming, the degree of flame extension, the fuel/air equivalence ratio and the thermal
environment. Similarly, these parameters shallshould be known for a real-scale fire test.
The yields of toxic gases, the combustion efficiency and the equivalence ratio are likely to be sensitive to
the manner in which the test specimen is sampled from the whole commercial product. There can be
difficulty or alternative ways of obtaining a proper test specimen. That is not the subject of this
document, which presumes that a specimen has been selected for study and characterizes the
combustion conditions and the yields of effluent species for that specimen.
For those experimental fires in which time-resolved data are available, the methods in this document
shallshould be used to produce either instantaneous or averaged values. The application can be
influenced by changes in the chemistry of the test specimen during combustion. For those fire tests
limited to producing time-averaged gas concentrations, the calculated values produced by the methods
in this document are limited to being averages as well. In real fires, combustion conditions, the fuel
chemistry and the composition of fire effluent from many common materials and products vary
continuously during the course of the fire. Thus, how well the average yields obtained using these
methods correspond to the yields in a given real fire has much to do with the stage of the fire, the pace
of fire development and the chemical nature of the materials and products exposed.
This document provides definitions and equations for the calculation of toxic product yields and the fire
conditions under which they have been derived in terms of equivalence ratio and combustion efficiency.
Sample calculations for practical cases are provided.
ISO/FDIS 19703:2018(E)
Generation and analysis of toxic gases in fire — Calculation of
species yields, equivalence ratios and combustion efficiency in
experimental fires
1 Scope
This document provides definitions and equations for the calculation of toxic product yields and the fire
conditions under which they have been derived in terms of equivalence ratio and combustion efficiency.
Sample calculations for practical cases are provided. The methods are intended to be used to produce
either instantaneous or averaged values for those experimental fires in which time-resolved data are
available.
This document is intended to provide guidance to fire researchers for
— recording appropriate experimental fire data,
— calculating average yields of gases and smoke in fire effluents in fire tests and fire-like combustion
in reduced scale apparatus,
— characterizing burning behaviour in experimental fires in terms of equivalence ratio and
combustion efficiency using oxygen consumption and product generation data.
This document does not provide guidance on the operating procedure of any particular piece of
apparatus or interpretation of data obtained therein (e.g. toxicological significance of results).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 13943, Fire safety — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943 and the following
apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
mass concentration of gas
mass of gas per unit volume
Note 1 to entry: The mass concentration of a gas shall be derived directly from the measured volume fraction and
its molar mass or measured directly.
Note 2 to entry: Mass concentration is typically expressed in units of grams per cubic metre.
ISO/FDIS 19703:2018(E)
3.2
mass concentration of particles
mass of solid and liquid aerosol particles per unit volume
Note 1 to entry: Mass concentration of particles is typically expressed in units of grams per cubic metre.
3.3
molar mass
mass of 1 mole
Note 1 to entry: Molar mass is normally expressed in units of grams per mole.
3.4
recovery of element
〈in a specified combustion product〉 degree of conversion of an element in the test specimen to a
corresponding gas, i.e. a ratio of the actual yield to notional yield of the gas containing that element
Note 1 to entry: It is the ratio of the actual yield to notional yield of the gas containing that element.
3.5
relative atomic mass
average mass of one atom of an element divided by one twelfth of the mass of one atom of carbon
(isotope C)
3.6
stoichiometric oxygen-to-fuel mass ratio
amount of oxygen needed by a material for complete combustion
Note 1 to entry: Stoichiometric oxygen-to-fuel mass ratio is typically expressed in units of grams of oxygen per
gram or kilogram of burnt material.
3.7
uncertainty
uncertainty of measurement
parameter, associated with the result of a measurement, that characterizes the dispersion of the values
whichthat could reasonably be attributed to the measurement
Note 1 to entry: The description and propagation of uncertainty in measurements are described in
[24]
ISO/IEC Guide 98-3 .
[SOURCE: ISO/IEC Guide 98-3:2008, 2.2.3, modified—The term has been changed from “uncertainty (of
measurement)” to “uncertainty”; “uncertainty of measurement” has been added as an admitted term;
the original Notes 1, 2 and 3 to entry have been deleted and a new Note 1 to entry has been added.]
3.8
expanded uncertainty
quantity defining an interval about the result of a measurement that may be expected to encompass a
large fraction of the distribution of values that could reasonably be attributed to the measurement
Note 1 to entry: Adapted from ISO/IEC Guide 98-3:2008, 2.3.5.
4 Symbols and units
Table 1 — Symbols
ISO/FDIS 19703:2018(E)
Symbol Quantity Typical unit
A extinction area of smoke square metre
Aσf or ASEA specific extinction area of smoke per unit mass of material burned square metres per gram
or square metres per
kilogram
DMO mass optical density (lg10log10 analogue of ASEA) square metres per gram
or square metres per
kilogram
F recovery fraction of element E in gas containing E dimensionless
R,E
ΔHact measured heat release in a combustion kilojoules per gram
ΔH net heat of combustion or enthalpy generated in complete combustion kilojoules per gram
c
I/Io fraction of light transmitted through smoke dimensionless
L is the length of the light path through the smoke metre
mA,E relative atomic mass of the element E dimensionless
m mass fraction of element E in the material dimensionless
E
mfuel mass of fuel gram
m total mass of the gas of interest gram
gas
mm,loss total mass loss of material gram
material mass loss rate grams per minute
m
m,loss
m actual mass of oxygen available for combustion gram
O,act
m
O ,act
actual mass flow of oxygen available for combustion grams per minute
m
O,act
m stoichiometric mass of oxygen required for complete combustion gram
O,stoich
mpart total mass of particles gram
M molar mass of the gas of interest grams per mole
gas
Mpoly molar mass of the polymer unit grams per mole
n number of atoms of element E in one molecule of gas dimensionless
E
nE,poly number of atoms of element E in the polymer unit dimensionless
P ambient pressure kilopascal
amb
Pstd standard pressure 101,3 kPa
T thermodynamic temperature of the gas of interest at the point of kelvin
C
measurement
V volume of chamber cubic meter
Veff total volume of fire effluent cubic metre
volume air flow cubic metres per minute
V
air
w measured mass fraction of oxygen consumed per unit mass of fuel dimensionless
O,cons
wO,der derived mass fraction of oxygen consumed per unit mass of fuel dimensionless
w mass fraction of oxygen in polymer that contributes to the formation dimensionless
Oex,poly
of oxygen-containing products
ISO/FDIS 19703:2018(E)
w mass fraction of oxygen consumed in the form of the major oxygen- dimensionless
O,gases
containing products (wO,CO2 + wO,CO + wO,H2O)
w mass fraction of oxygen in the polymer dimensionless
O,poly
Ygas measured mass yield of gas of interest dimensionless
Y measured mass yield of smoke particles dimensionless
part
α linear decadic absorption coefficient (or optical density) inverse metre
α light extinction coefficient inverse metre
k
χ combustion efficiency dimensionless
χ combustion efficiency calculated from the generation efficiency of dimensionless
cox
carbon in the fuel to oxides of carbon
χ combustion efficiency calculated from oxygen depletion dimensionless
O
χprod combustion efficiency calculated from the oxygen in the major dimensionless
combustion products
ϕ equivalence ratio dimensionless
η generation efficiency for oxides of carbon dimensionless
φgas volume fraction of the gas of interest dimensionless
φ volume fraction oxygen in the air supply (0,209 5 for dry air) dimensionless
O
ρgas mass concentration of the gas of interest grams per cubic metre
ρ mass loss concentration of the material grams per cubic metre
m,loss
ρ O,act actual mass concentration of oxygen available for combustion grams per cubic metre
ρ mass concentration of the smoke particles grams per cubic metre
part
σm,α mass specific extinction coefficient square metres per gram
or square metres per
kilogram
Ψgas notional yield (mass fraction) of gas of interest dimensionless
Ψ stoichiometric oxygen-to-fuel mass ratio dimensionless
O
5 Appropriate input data required for calculations
5.1 Data handling
5.1.1 Uncertainty
In calculating the fire parameters described in this document, the uncertainty or error associated with
[1]
each component shall be taken into account and they shall be combined in the correct manner .
Uncertainty is derived from accuracy (how close the measured value is to the true value) and precision
(how well the values agree with each other). There are uncertainties relating to physically measured
parameters (e.g. mass loss and gas concentrations).
Assuming all errors to be independent, the total error, δq, is obtained by summing the squares of the
errors in accordance with the general Formula (1):
qq
q a . z (1)
az
ISO/FDIS 19703:2018(E)
In other words, evaluate the error caused by each of the individual measurements, then combine them
by taking the root of the sum of the squares.
In empirically derived equations, uncertainties in “constant” values shall be treated similarly to
measurement uncertainties. If a constant is truly constant, i.e. has negligible uncertainty, it can be
neglected.
5.1.2 Significant figures and rounding off
When recording and reporting data, significant figures shall be handled properly. The general approach
is to carry one digit beyond the last certain one. When rounding off, the typical rule is to round up when
the figure to be dropped is 5 or more and round down when it is less than 5.
5.2 Test specimen information
5.2.1 Composition
Information shall be given where possible on the combustible fraction, organic and inorganic
combustible components, inert components, elemental composition, empirical formula and molecular
or formula weight.
Where the combustible in a fire experiment is a single, homogenous material, perhaps with dispersed
additives, the molecular formula of the material shall be provided. Commercial products, however, are
generally non-homogeneous combinations of materials, with each component containing one or more
polymers and possibly multiple additives. For complex materials representative of commercial
products, the yields, effective heats of combustion, etc. vary with time as the various components
become involved. For some of the following (global) calculations, a simplification is the use of an
empirical formula for the composite.
5.2.2 Net heat of combustion
The net heat of combustion for combustible components shall be required for some of the calculations
(e.g. combustion efficiency).
5.3 Fire conditions
5.3.1 Apparatus
Give the name of the apparatus with a brief description of mode of operation (e.g. flow-through steady
state, calorimeter and closed chamber system). Refer to the appropriate standard or other reference
relating to the procedure.
5.3.2 Set-up procedure
The fire conditions are generally apparatus-dependent and largely dictated by the set-up procedure for
the particular apparatus. The following information shall be required:
a) test specimen details, its mass, dimensions and orientation of the combustible;
b) thermal environment, in terms of the temperature (expressed in degrees Celsius) and irradiance
(expressed in kilowatts per square metre) to which test specimen is subjected;
NOTE The temperature distribution and the radiation field in a test are frequently not uniform and, as a
result, are rarely well documented. Sufficient information about the thermal and radiative conditions is intended
to allow another person to reproduce the results using the same apparatus, compare the results with results for
the same specimen tested in another apparatus, etc.
c) oxygen concentration in the air supply (volume percent or volume fraction);
d) volume of chamber or air flow. For a closed system, give the air volume (expressed in litres or cubic
metres) and for an open system, give the air flow (expressed in litres per minute or in cubic metres
ISO/FDIS 19703:2018(E)
per minute) and the dynamics of the flow. In both cases, give information on the atmospheric
mixing conditions and the degree of homogeneity of the fire effluent.
5.4 Data collection
5.4.1 Data acquisition
Time-resolved data or time-integrated data may be acquired. The method of data acquisition shall be
specified in the test protocol.
5.4.2 Measured data and observations
Most of the following data parameters shall be used to calculate yields, equivalence ratios and
combustion efficiencies in experimental fires. Usually, the units applied to data should be dictated by
the operational procedure associated with a particular piece of apparatus. The following are a number
of suggested typical units:
a) mass loss of the test specimen, derived by measuring the test specimen mass before and after test
to give overall mass loss (expressed in milligrams, grams or kilograms) or mass loss fraction
(expressed in mass percent, grams per gram or kilograms per kilogram), or by measuring the
specimen mass throughout a test to give mass loss rate (expressed in milligrams per second, grams
per minute or kilograms per minute);
b) gas and vapour concentrations and oxygen depletion (expressed in volume percent, volume
fraction, microlitres per litre, milligrams per litre or milligrams per cubic metre);
c) smoke particulate concentration (expressed in milligrams per litre or milligrams per cubic metre)
and smoke obscuration (expressed in optical density per metre or square metres per kilogram);
d) heat release (expressed in kilojoules per gram), used to calculate combustion efficiency, forms part
of the protocol for some apparatuses;
e) combustion mode, time to ignition (expressed in minutes or seconds) and whether the specimen
flames or not throughout the test.
6 Calculation of yields of fire gases and smoke, stoichiometric oxygen-to-fuel
mass ratio and recovery of key elements
6.1 Calculation of measured yields from fire gas concentration data
In experimental fires, the mass yield, Y , of a gas shall be calculated from the measured mass
gas
concentration of the gas of interest and the mass loss concentration of the material in accordance with
Formula (2) (see NOTES 1, 2 and 3):
gas
Y (2)
gas
m,loss
where
ρ is the mass concentration of the gas;
gas
ρ is the mass loss concentration of the material.
m,loss
Alternatively, Y shall be calculated from the total mass of gas generated and the total mass loss of
gas
material in accordance with Formula (3):
ISO/FDIS 19703:2018(E)
m
gas
Y (3)
gas
m
m,loss
where
m is the total mass of the gas;
gas
m is the total mass loss of the material.
m,loss
NOTE 1 These calculations can be derived from instantaneous data or from data which assumes that the gases
are uniformly dispersed in a certain volume and that this volume is the same one in which the lost sample mass is
(evenly) dispersed. If the dispersion is not uniform, the equations still work if the lost mass and the gas in
question are dispersed equivalently. If a combustion gas is prone to surface losses within the apparatus, the
apparent yield depends on where the concentration is being measured.
NOTE 2 In flow-through devices, the total effluent is generally well mixed at some distance downstream. For
closed-box combustion systems, it is not necessarily so, especially if there are large molecular weight differences
and large thermal gradients. If multiple fuels are involved, only some averaged combined yield can be calculated.
NOTE 3 In setting up these calculations, uncertainties relating to lost sample mass, fluctuations in the
measured concentration, etc. occur.
The uncertainty shall be monitored. The calculated yield shall take account of and combine these
uncertainties, enabling a sound basis for comparing yields under different combustion conditions,
comparing yields from different materials and so on.
Whilst concentrations of the specific gas are most often measured in volume fractions,
Formulae (4) and (5) show how to convert the volume fraction of a gas to its mass concentration:
M
273,15K P
gas
amb
(4)
gas gas
31
T 101,325kPa
22,414 dm mol
C
where
ρ ρ is the mass concentration of the gas;
gas gas
φ is the volume fraction of the gas;
gas
M is the molar mass of the gas;
gas
T is the thermodynamic temperature of the gas at the point of measurement;
C
P is the ambient pressure;
amb
273,15 K is the standard thermodynamic temperature;
101,325 kPa is the standard pressure;
3 −1
22,414 dm ⋅mol is the molar volume of an ideal gas at standard temperature and pressure.
Thus, for fire effluent at 20 °C and standard pressure, Formula (4) simplifies to Formula (5):
M M
gas gas
(5)
gas gas gas gas
31 31
22,055dm mol 24,055dm mol
EXAMPLE The calculations for a well-ventilated fire atmosphere where mass loss concentration of the
−3
material is 25 g⋅m and the volume fraction of carbon monoxide (CO) is 0,125% (or 0,001 25) at 20 °C are shown
in Formulae (6) and (7):
1
28,01 gmol
33
0,00125 0,001 456 gdm 1,456 gm (6)
CO
31
24,055dm mol
ISO/FDIS 19703:2018(E)
33 33
Y 1,456 gm /25m 0,0582 Y 1,456 gm /25gm 0,0582 (7)
co co
where
ρ is the mass concentration of CO;
CO
Y is the mass yield of CO (mass of CO per unit mass of material);
CO
−1
28,01 g⋅mol is the molar mass of CO.
The relative atomic mass, molar mass and gas concentration conversion factors for the major fire gases
are listed in Tables 2 and 3.
[2]
Table 2 — Relative atomic mass of key fire gas elements
a
Element Symbol Relative atomic mass
Carbon C 12,011
Hydrogen H 1,0079
Oxygen O 15,999
Nitrogen N 14,007
Chlorine Cl 35,453
Bromine Br 79,904
Fluorine F 18,998
Sulfur S 32,065
Phosphorus P 30,973
Antimony Sb 121,76
a
Relative atomic mass values rounded to five significant figures.
Table 3 — Molar masses of common fire gases and volume fraction/mass concentration
conversion factors
Gas or vapour Formula Molar Gas concentration conversion factors
a
mass (at 20 °C and 101,3 kPa)
−1
g·mol
To convert volume fraction to To convert concentration to
concentration, volume fraction,
multiply by density of the gas: divide by density of the gas:
b −3
Carbon dioxide CO 44,01 1 830 g.m
b −3
Carbon monoxide CO 28,01 1 164 g.m
−3
Hydrogen cyanide HCN 27,02 1 124 g.m
−3
Nitrogen dioxide NO2 46,01 1 913 g.m
−3
Nitrous oxide N O 44,01 1 831 g.m
−3
Nitric oxide NO 30,01 1 248 g.m
−3
Ammonia NH 17,03 708 g.m
−3
Hydrogen chloride HCl 36,46 1 516 g.m
−3
Hydrogen bromide HBr 80,91 3 364 g.m
−3
Hydrogen fluoride HF 20,01 832 g.m
ISO/FDIS 19703:2018(E)
−3
Hydrogen sulfide H S 34,08 1 417 g.m
−3
Sulfur dioxide SO2 64,06 2 663 g.m
−3
Water H O 18,01 749 g.m
−3
Phosphoric acid H3PO4 97,99 4 074 g.m
−3
Acrolein C H O 56,06 2 331 g.m
3 4
−3
Formaldehyde CH2O 30,03 1 248 g.m
−3
Oxygen O 32,00 1 331 g.m
NOTE The concentration of a gas equals to volume fraction x density.
Example calculations:
4 −3 −3
If φ = 0,01 (i.e. 1 % or 10 μl/l), m = 0,01 × 1 164 g⋅m =11,64 g⋅m .
CO CO
−3 −3 −3
If m HCN = 0,281 g⋅m , φ HCN =0,281 g⋅m /1 124 g⋅m =0,000 25 (i.e. 0,025 % or 250 μl/l).
a
Molar mass values are rounded to two decimal places.
b
CO /CO volume ratio equals the CO /CO mass ratio divided by 1,571.
2 2
6.2 Calculation of notional gas yields
6.2.1 General
The notional yields of gases and vapours are a measure of the maximum theoretical combustion
product yields. They are based on the composition of the material and are entirely material-dependent.
Two primary methods for calculating notional yields are described in 6.2.2 and 6.2.3.
6.2.2 From the elemental composition
Provided the elemental composition of the base material is known (e.g. by elemental analysis), the
maximum possible (notional) yield, Ψ , of fire gas corresponding to each specified element, E, is
gas
calculated in accordance with Formula (8):
M
gas
m (8)
gas E
nm
E A,E
where
m is the mass fraction of element E in the material;
E
M is the molar mass of the gas which is under consideration;
gas
n is the number of atoms of element E in one molecule of the gas;
E
m is the relative atomic mass of the element E;
A,E
EXAMPLE The notional yield, ΨCO, of CO from cellulose, (C6H10O5)n, is calculated as given by Formula (9):
1
28,01 gmol
0,445 1,038 (9)
CO
1
112,011 g mol
where
0,445 is the mass fraction of carbon in the cellulose;
−1
28,01 g⋅mol is the molar mass of CO;
1 is the number of atoms of carbon in one molecule of CO;
−1
12,011 g⋅mol is the molar mass of carbon.
ISO/FDIS 19703:2018(E)
Factors for calculating notional gas yields from the elemental composition and derived from the term
M
gas
in Formula(8), are given in Table 4.
nm
E A,E
Table 4 — Factors for calculating notional gas yields from the elemental composition of material
a
Gas or vapour Element E considered in base Factor
material
Formula Molar mass
g⋅mol-1
CO2 44,01 carbon 3,664
CO 28,01 carbon 2,332
H2O 18,02 hydrogen 8,939
HCN 27,02 nitrogen 1,929
NO2 46,01 nitrogen 3,284
N O 44,01 nitrogen 1,571
NO 30,01 nitrogen 2,142
NH 17,03 nitrogen 1,216
HCl 36,46 chlorine 1,028
HBr 80,92 bromine 1,013
HF 20,01 fluorine 1,053
H S 34,08 sulfur 1,063
H3PO4 97,98 phosphorus 3,163
SO 64,06 sulfur 1,998
Acrolein (C3H4O) 56,06 carbon 1,556
Formaldehyde 30,03 carbon 2,500
(CH2O)
M
gas
a
Factor rounded to four significant figures.
nm
E A,E
6.2.3 From the empirical formula
If the empirical formula of the material is known, the notional yield, Ψ , shall be calculated from
gas
Formula (10):
nM
E,poly gas
(10)
gas
nM
E poly
where
n is the number of atoms of element E in the empirical formula;
E,poly
M is the molar mass of the empirical formula.
poly
EXAMPLE The notional yield, , of carbon dioxide (CO2) from polypropylene with the empirical formula
CO
(C3H6) is calculated as shown in Formula (11):
ISO/FDIS 19703:2018(E)
1
3 44,01 gmol
3,142 (11)
CO
2 1
42,03 gmol
where
is expressed in grams of CO per gram of polymer;
2
CO
1 is the number of atoms of carbon in one molecule of CO ;
3 is the number of atoms of carbon in the polymer unit;
−1
44,01 g⋅mol is the molar mass of CO ;
−1
42,03 g⋅mol is the molar mass of the polymer unit.
NOTE The notional yield of a gas that contains more than one element from the fuel molecule is determined
by the least prevalent element (other than oxygen). Thus, the notional yield of HCN can be most often determined
by the nitrogen content of the fuel. However, for a product gas like formaldehyde, it can be either the carbon or
hydrogen fraction that provides the criterion, depending on the fuel composition.
6.3 Calculation of recovery of elements in key products
The recovery fraction of an element in a key combustion product (alternatively, the conversion
efficiency of an element in the test specimen to a corresponding gas ) shall be calculated from the
measured yield, Y , of the gas of interest relative to its notional yield, Ψ . For a material containing
gas
gas
element E, this corresponds to Formula (12):
η = Y /Ψ (12)
E, gas gas gas
where
Y is derived from Formulae (2) to (7);
gas
Ψ is derived from Formulae (8) to (11);
gas
η is the recovery fraction or conversion efficiency of element E in gas containing E.
E, gas
6.4 Calculation of stoichiometric oxygen-to-fuel mass ratio
6.4.1 General
Stoichiometric oxygen-to-fuel mass ratio is the amount of oxygen needed by a material for complete
combustion. Its derivation is somewhat more complex than notional gas yields and should be calculated
by one of the three primary methods as described in 6.4.2 to 6.4.4.
6.4.2 From the chemical equation for complete combustion
6.4.2.1 For fuels containing C, H, O, for complete combustion to carbon dioxide and water
For the complete combustion of fuels containing C, H, O, the products only consist of CO and gaseous
H O. For organic fuels which contain oxygen, the requirement of oxygen from air for complete
combustion is less than for those which do not contain oxygen. For a polymer with the general formula
C H O , Formulae (13) to (15) apply:
a b c
C H O + zO → aCO + b/2 H O (13)
a b c 2 2 2
and
22ab c
z (14)
where
ISO/FDIS 19703:2018(E)
z is the (stoichiometric) number of moles of O required for complete combustion of one mole of
C H O ;
a b c
a is the number of atoms of carbon in C H O ;
a b c
b is the number of atoms of hydrogen in C H O ;
a b c
c is the number of atoms of oxygen in C H O .
a b c
The stoichiometric oxygen-to-fuel mass ratio required for complete combustion is then calculated from
Formula (15):
z32,00
(15)
O
M
poly
where
Ψ is the stoichiometric oxygen-to-fuel mass ratio, expressed in grams of oxygen per
O
gram of polymer;
−1
32,00 g⋅mol is the molar mass of oxygen.
EXAMPLE The stoichiometric combustion equation for polymethyl methacrylate (PMMA) is given by
Formulae (16) and (17):
C H O + 1,20 O → CO + 0,80 H O (16)
1,0 1,6 0,4 2 2 2
1,2032,00
1,918 (17)
O
20,02
where
1,0 is the number of atoms of carbon in C H O ;
1,0 1,6 0,4
1,6 is the number of atoms of hydrogen in C H O ;
1,0 1,6 0,4
0,4 is the number of atoms of oxygen in C H O ;
1,0 1,6 0,4
1,20 is the (stoichiometric) number of moles of O2 required for complete combustion of one
mole of C H O ;
1,0 1,6 0,4
1,918 is the calculated stoichiometric oxygen-to-fuel mass ratio of PMMA, expressed in grams of
oxygen per gram of PMMA.
6.4.2.2 For fuels containing hetero-elements
For the complete combustion of fuels containing (organically-bound) elements in addition to C, H and O,
it is assumed that nitrogen generates gaseous N , halogens generate gaseous acid gases (HCl, HBr, etc.)
and sulfur generates gaseous SO .
Combustion equations for this type of test material are more complex because, for example, hydrogen
from the material is used to form acid gases as well as water and sulfur consumes oxygen to form SO .
For a halogenated material with the general formula of C H O N Cl Br F S , the equation for
a b c d e f g h
stoichiometric oxygen-to-fuel mass ratio is given by Formula (18):
2a2hc be f g 2
(18)
z
where
z is the (stoichiometric) number of moles of O required for complete combustion of one mole of
C H O N Cl Br F S ;
a b c d e f g h
ISO/FDIS 19703:2018(E)
a is the number of atoms of carbon in C H O N Cl Br F S ;
a b c d e f g h
b is the number of atoms of hydrogen in C H O N Cl Br F S ;
a b c d e f g h
c is the number of atoms of oxygen in C H O N Cl Br F S ;
a b c d e f g h
d is the number of atoms of nitrogen in C H O N Cl Br F S ;
a b c d e f g h
e is the number of atoms of chlorine in C H O N Cl Br F S ;
a b c d e f g h
f is the number of atoms of bromine in C H O N Cl Br F S ;
a b c d e f g h
g is the number of atoms of fluorine in C H O N Cl Br F S ;
a b c d e f g h
h is the number of atoms of sulphur in C H O N Cl Br F S .
a b c d e f g h
EXAMPLE The stoichiometric combustion equation for unplasticized polyvinyl chloride (C2H3Cl) is given by
Formulae (19) to (20):
C H Cl + 2,5 O → 2CO + H O + HCl (19)
2 3 2 2 2
and
2,532,00
(20)
1,280
O
62,5
where
2,5 is the (stoichiometric) number of moles of O required for complete combustion of
one mole of C H Cl;
2 3
−1
62,5 g⋅mol is the molar mass of C H Cl;
2 3
1,280 is the calculated stoichiometric oxygen-to-fuel mass ratio for C H Cl, expressed in
2 3
grams of oxygen per gram of C H Cl.
2 3
6.4.3 From the net heat of combustion, ΔH
c
It has been empirically determined that when a material burns, for every gram of oxygen consumed, the
−1 [3]
heat released is approximately 13,1 kJ⋅g (accurate to ±5 %) . Thus, if the net heat, ΔH , generated in
c
complete combustion is known (e.g. as measured by bomb calorimetry), the stoichiometric oxygen-to-
fuel mass ratio shall be calculated as given by Formula (21):
Ψ = ΔH /13,1 (21)
O c
where
ΔH is the net heat or enthalpy per unit mass of fuel consumed, generated in complete
c
combustion. It assumes that any water produced is in the gaseous state.
EXAMPLE The calculation for polystyrene is shown in Formula (22):
Ψ = 39,2/13,1 = 2,99 (22)
O
where
−1
39,2 kJ⋅g is the net heat of complete combustion for polystyrene;
2,99 is the calculated stoichiometric oxygen-to-fuel mass ratio for polystyrene, expressed in
grams of oxygen per gram of polystyrene.
−1
NOTE From its chemical composition, Ψ for polystyrene is 3,07 g⋅g .
O
ISO/FDIS 19703:2018(E)
6.4.4 From the carbon content of the material
There is a less accurate correlation between the carbon content and stoichiometric oxygen-to-fuel mass
ratio of polymeric materials empirically derived from the carbon content where the correlation
coefficient, R , is 0,933, as shown in Formula (23):
Ψ = (m × 3,87) − 0,339 9 (23)
O,poly C
where
m is the mass fraction of carbon in the material;
C
3,87 and 0,339 9 are empirically-derived mathematical coefficients.
EXAMPLE The calculation for polymethyl methacrylate is given by Formula (24):
Ψ = (0,60 × 3,87) − 0,339 9 = 1,98 (24)
O
where
0,60 is the mass fraction of carbon in PMMA;
1,98 is the calculated stoichiometric oxygen-to-fuel mass ratio for PMMA, expressed in grams O
per gram of PMMA.
−1
NOTE From its chemical composition, Ψ for PMMA is 1,918 g⋅g .
O
The step-wise procedures for calculating notional gas yields and stoichiometric oxygen-to-fuel mass
ratio for a polymer containing C, O, H and X and for polyamide using chemical equation methods are
summarized in Table 5.
Three methods for calculating stoichiometric oxygen-to-fuel mass ratio for selected polymers are
compared in Table 6.
Notional gas yields and stoichiometric oxygen-to-fuel mass ratio derived for a number of common
polymers are listed in Tables 7, 8 and 9.
Table 5 — Example calculations for notional gas yields and stoichiometric oxygen-to-fuel mass
ratio for a polymer containing C, O, H, X and for polyamide using chemical equation methods
Polymer Contains C, H, O, X Polyamide
Empirical formula C H O X C H O N
a b c d 12 22 2 2
b
(C1H1,83O0,17N0,17)
Molar mass of polymer (12 × a) + (1 × b) + (16 × c) + (m × d) (12 × 12) + (1 × 22) + (16 × 2) + (14 × 2) =
A,X
M , grams a 226
poly
(= 18,83 relative to each C atom)
−1
Notional yield CO a/1 × 44/M 12 × 44/226 = 2,336 g⋅g
2 poly
, grams per gram
CO
−1
Notional yield CO a/1 × 28/Mpoly 12 × 28/226 = 1,487 g⋅g
ΨCO, grams per gram
−1
Notional yield H O b/2 × 18/M 22/2 × 18/226 = 0,876 g⋅g
2 poly
, grams per gram
HO
Stoichiometric oxygen-to- (2a + b/2 − c)/2 (24 + 11 − 2)/2 = 16,5 mol
c
fuel mass ratio, z moles O
ISO/FDIS 19703:2018(E)
−1
Stoichiometric oxygen-to- z mol × 32/M 16,5 × 32/226 = 2,336 g⋅g
poly
fuel mass ratio of polymer
ΨO,poly, grams per gram
a
m is the relative atomic mass of the element X, expressed in grams per mole.
A,X
b
Empirical formula re-based to one carbon atom.
c
This assumes that nitrogen in the material is converted to N . In practice, a small proportion is converted to nitrogen
products containing hydrogen or oxygen. The error is considered to be small.
Table 6 — Examples of stoichiometric oxygen-to-fuel mass ratio derived by three methods
Stoichiometric oxygen -to-fuel mass
ratio of polymer, Ψ
O,poly
−1
Mass
g⋅g
a,b,c
ΔH
Empirical fraction of
c
Generic polymer type
−1 From
formula carbon in
kJ⋅g
From
elemental
polymer mC
d
From ΔHc carbon
compositio
e
content
n
Polyethylene C H 43,1 to 43,6 0,857 3,420 3,29 to 3,32 2,98
2 4
Polystyrene C8H8 39,2 to 39,9 0,923 3,080 2,99 to 3,05 3,23
Polymethylmethacrylate C H O 24,9 to 25,2 0,600 1,920 1,90 to 1,92 1,98
5 8 2
Polycarbonate C16H14O3 29,7 to 29,8 0,754 2,260 2,27 2,58
Polyethylene C H O 21,3 to 22,0 0,625 1,665 1,63 to 1,68 2,08
10 8 4
terephthalate
Polyester, unsaturated C H O 20,3 to 28,5 0,682 2,051 1,55 to 2,18 2,30
5,77 6,25 1,63
Polyvinyl chloride C2H3Cl 16,4 to 16,9 0,384 1,280 1,25 to 1,29 1,15
Polytetrafluoroethylene C F 6,2 to 5,00 0,240 0,640 0,473 0,59
2 4
Polyacrylonitrile C3H3N 30,8 to 31,0 0,679 2,270 2,35 to 2,37 2,29
Polyamide C H NO 29,5 to 30,8 0,637 2,330 2,25 to 2,35 2,13
6 11
Polyurethane foam, rigid C6,3H7,1NO2,1 ~27 to 22,7 0,662 2,100 2,06 to 1,73 2,22
Polyurethane foam, — 23,2 to 31,6 — — 1,77 to 2,41 —
flexible
Wool — 20,7 to 26,6 — — 1,58 to 2,03 —
Cellulosics (e.g. CH1,7O0,83 16,0 to 20,4 0,445 1,197 1,22 to 1,56 1,38
pinewood)
a
Reference [4].
b
Reference [5].
c
Reference [6].
d [3]
Calculation uses 13,1 as a divisor .
e
From empirical correlation derived from data given in References [4],[5] and [6]; see Formula (23) where
ΨO,poly = (mC × 3,87) − 0,339 9 and R = 0,933.
Table 7 — Notional gas yields and stoichiometric oxygen-to-fuel mass ratio for common
polymers
containing C, H, O, in the structure
b
Material Empirical Notional gas yields
formula
ISO/FDIS 19703:2018(E)
Mass fraction
a
Ψ Ψ Ψ
O CO2 CO
of carbon in
−1 −1 −1
g⋅g g⋅g g⋅g
polymer mC
Polyethylene CH2 0,857 3,421 3,140 2,000
Polypropylene CH 0,857 3,421 3,140 2,000
Polystyrene CH 0,923 3,070 3,380 2,150
Polymethylmethacrylate CH O 0,600 1,920 2,200 1,400
1,6 0,40
Cellulose CH1,7O0,83 0,445 1,197 1,630 1,040
Viscose CH O 0,44,5 1,197 1,630 1,040
1,7 0,83
c
Polyester CH1,4O0,22 0,709 2,340 2,600 1,650
Polyethylene CH O 0,625 1,667 2,292 1,458
0,80 0,40
terephthalate
Polycarbonate CH O 0,754 2,260 2,760 1,760
0,88 0,19
a
Stoichiometric oxygen-to-fuel mass ratio, ΨO, (used to calculate the equivalence ratio, ϕ) has been calculated from the
chemical composition of the polymer and the equation for complete combustion.
EXAMPLE 1 Stoichiometric oxygen-to-fuel mass ratio for complete combustion of polyethylene:
CH + 1,5 O = CO + H O;
2 2 2 2
14,03 g + 48,00 g→48,00/14,03;
−1
Ψ = 3,421 g⋅g .
O
EXAMPLE 2 Stoichiometric oxygen-to-fuel mass ratio for complete combustion of polyester:
CH O + 1,24O = CO + 0,7 H O;
1,4 0,22 2 2 2
16,92 g + 39,70 g→39,70/16,92;
−1
Ψ = 2,346 g⋅g .
O
b
Notional gas yields, expressed in grams per gram: = mC × 3,67;
CO
Ψ = m × 2,33.
CO C
c
The values given in this table are examples only and not necessarily characteristic of the whole family of polymers.
Table 8 — Notional gas yields and stoichiometric oxygen-to-fuel mass ratio for common
polymers
containing C, H, O, N in the structure
d
Notional gas yields
a
b
Material Empirical formula
ΨO CO ΨCO ΨHCN NO
2 2
mC mN
−1 −1 −1
g⋅g g⋅g g⋅g
−1 −1
g⋅g g⋅g
Poly CHN 0,681 0,264 2,270 2,500 1,590 0,510 0,870
0,33
acrylonitrile
PAN
Polyamide CH O N 0,637 0,126 2,330 2,330 1,480 0,240 0,415
1,8 0,17
0,17
Polyurethane CH1,8O0,35N0,06 0,593 0,042 2,010 2,170 1,380 0,080 0,140
foam, flexible
Polyurethane CH1,2O0,22N0,10 0,662 0,077 2,100 2,430 1,545 0,150 0,250
foam, rigid
ISO/FDIS 19703:2018(E)
Polyisocyanurat CH O N 0,682 0,088 2,100 2,430 1,545 0,171 0,286
1,0 0,19 0,11
e foam, rigid
Aramid fibres CH O N 0,710 0,118 2,094 2,600 1,650 0,230 0,390
0,71 0,14 0,14
c
Wool CH1,62O0,38N0,27S0,03 0,491 N = 0,15 1,590 1,800 1,145 0,290 0,490
S = 0,039
O = 0,24
a
The values given in this table are examples only and not necessarily characteristic of the whole family of polymers.
b
Stoichiometric oxygen-to-fuel mass ratio, Ψ (used to calculate equivalence ratio, ϕ) has been calculated from the chemical
O
,
composition of the polymer and the equation for complete combustion.
c
Approximate values for wool.
d
Notional gas yields: = mC × 3,67;
CO
ΨCO = mC × 2,33;
Ψ = m × 1,93;
HCN N
= mN × 3,29.
NO
Table 9 — Notional gas yields and stoichiometric oxygen-to-fuel mass ratio for common
a
polymers containing C, H,
...
NORME ISO
INTERNATIONALE 19703
Troisième édition
2018-06
Production et analyse des gaz
toxiques dans le feu — Calcul des
taux de production des espèces,
des rapports d'équivalence et de
l'efficacité de combustion dans les
feux expérimentaux
Generation and analysis of toxic gases in fire — Calculation of
species yields, equivalence ratios and combustion efficiency in
experimental fires
Numéro de référence
©
ISO 2018
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ii © ISO 2018 – Tous droits réservés
Sommaire Page
Avant-propos .v
Introduction .vi
1 Domaine d’application . 1
2 Références normatives . 1
3 Termes et définitions . 1
4 Symboles et unités . 3
5 Données d’entrée appropriées pour les calculs . 4
5.1 Traitement des données . 4
5.1.1 Incertitude . 4
5.1.2 Chiffres significatifs et arrondi . 5
5.2 Information sur les éprouvettes d’essai . 5
5.2.1 Composition . 5
5.2.2 Pouvoir calorifique inférieur . 5
5.3 Conditions de combustion . 5
5.3.1 Appareillage . 5
5.3.2 Mode opératoire de réglage. 5
5.4 Collecte des données . 6
5.4.1 Acquisition des données . 6
5.4.2 Données mesurées et observations . 6
6 Calcul des taux de production des gaz de combustion et de la fumée, du rapport
stœchiométrique de masse oxygène-combustible et de la régénération des
principaux éléments . 7
6.1 Calcul des taux de production mesurés à partir des données sur la concentration
en gaz de combustion . 7
6.2 Calcul des taux de production théoriques des gaz .10
6.2.1 Généralités .10
6.2.2 Calcul à partir de la composition élémentaire .10
6.2.3 Calcul à partir de la formule empirique .12
6.3 Calcul de la régénération des éléments dans les principaux produits .12
6.4 Calcul du rapport stœchiométrique de masse oxygène-combustible .13
6.4.1 Généralités .13
6.4.2 Calcul à partir de l’équation chimique de la combustion complète .13
6.4.3 Calcul à partir du pouvoir calorifique inférieur, ΔH .
c 15
6.4.4 Calcul à partir de la teneur en carbone du matériau .15
6.5 Calcul des taux de production des fumées .20
6.5.1 Généralités .20
6.5.2 Taux de production des fumées basés sur la masse des particules de fumée .20
6.5.3 Taux de production des fumées basés sur les propriétés d’extinction de la
lumière .21
6.5.4 Relation entre la mesure de la masse et l’extinction de la lumière .23
7 Calcul du rapport d’équivalence.23
7.1 Généralités .23
7.2 Calcul de ϕ pour les conditions expérimentales à état stable et à débit continu .25
7.3 Calcul de ϕ pour les conditions expérimentales de calorimétrie à débit continu .26
7.4 Calcul de ϕ pour les systèmes à chambre fermée .26
7.5 Calcul de ϕ dans les essais au feu de compartiment .26
8 Calcul de l’efficacité de combustion .27
8.1 Généralités .27
8.2 Efficacité du dégagement de chaleur .27
8.3 Efficacité basée sur la consommation d’oxygène .28
8.3.1 Généralités .28
8.3.2 Méthode basée sur l’appauvrissement en oxygène .28
8.3.3 Méthode basée sur la teneur en oxygène des produits .29
8.4 Méthode basée sur les oxydes de carbone .30
Bibliographie .35
iv © ISO 2018 – Tous droits réservés
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération mondiale d’organismes
nationaux de normalisation (comités membres de l’ISO). L’élaboration des Normes internationales est
en général confiée aux comités techniques de l’ISO. Chaque comité membre intéressé par une étude
a le droit de faire partie du comité technique créé à cet effet. Les organisations internationales,
gouvernementales et non gouvernementales, en liaison avec l’ISO participent également aux travaux.
L’ISO collabore étroitement avec la Commission électrotechnique internationale (IEC) en ce qui
concerne la normalisation électrotechnique.
Les procédures utilisées pour élaborer le présent document et celles destinées à sa mise à jour sont
décrites dans les Directives ISO/IEC, Partie 1. Il convient, en particulier de prendre note des différents
critères d’approbation requis pour les différents types de documents ISO. Le présent document a été
rédigé conformément aux règles de rédaction données dans les Directives ISO/IEC, Partie 2 (voir www
.iso .org/directives).
L’attention est attirée sur le fait que certains des éléments du présent document peuvent faire l’objet de
droits de propriété intellectuelle ou de droits analogues. L’ISO ne saurait être tenue pour responsable
de ne pas avoir identifié de tels droits de propriété et averti de leur existence. Les détails concernant
les références aux droits de propriété intellectuelle ou autres droits analogues identifiés lors de
l’élaboration du document sont indiqués dans l’Introduction et/ou dans la liste des déclarations de
brevets reçues par l’ISO (voir www .iso .org/brevets).
Les appellations commerciales éventuellement mentionnées dans le présent document sont données
pour information, par souci de commodité à l’intention des utilisateurs et ne sauraient constituer un
engagement.
Pour une explication de la nature volontaire des normes, la signification des termes et expressions
spécifiques de l’ISO liés à l’évaluation de la conformité, ou pour toute information au sujet de l’adhésion
de l’ISO aux principes de l’Organisation mondiale du commerce (OMC) concernant les obstacles
techniques au commerce (OTC) voir le lien suivant: www .iso .org/iso/fr/avant -propos .html.
Le présent document a été élaboré par le comité technique ISO/TC 92, Sécurité au feu, sous-comité SC 3,
Dangers pour les personnes et l’environnement dus au feu.
Cette troisième édition annule et remplace la deuxième édition (ISO 19703:2010) qui a fait l’objet d’une
révision technique.
Les principales modifications par rapport à l’édition précédente sont les suivantes:
— des symboles redondants ont été supprimés;
— des symboles manquants ont été ajoutés;
— les unités de certains symboles dans les formules et les tableaux ont été corrigées afin de se
conformer aux Directives ISO/IEC Directives, Partie 2;
— des formules inutiles ont été supprimées;
— des erreurs dans les formules ont été corrigées.
Introduction
Les comités techniques ISO TC 92/SC 3, ISO TC 92/SC 4 et IEC TC 89 considèrent qu’il convient de ne
pas réglementer les produits commerciaux en se basant uniquement sur le potentiel toxique des
effluents engendrés lorsque ledit produit est soumis à combustion dans un appareillage d’essai au
banc (conditions d’essais conventionnelles). Il est au contraire recommandé d’utiliser les informations
caractérisant le potentiel toxique des effluents dans le cadre d’une évaluation des risques d’incendie ou
des dangers du feu qui intègre les autres facteurs contribuant à déterminer l’ampleur et l’impact des
effluents. L’intention est que les conditions de la caractérisation:
a) de l’appareillage servant à produire les effluents; et
b) des effluents eux-mêmes;
soient exploitables dans ce type d’évaluation de la sécurité incendie.
Comme décrit dans l’ISO 13571, le temps disponible avant incapacité dans une situation d’incendie
est déterminé par l’exposition cumulée d’une personne aux composants des effluents du feu. Les
concentrations en espèces toxiques dépendent à la fois des taux de production initialement engendrés
et de la dilution successive dans l’air. Les taux de production sont généralement déterminés en
utilisant un appareillage d’essai au banc (dans lequel un échantillon de produit commercial est brûlé)
ou en soumettant le produit commercial à un essai au feu en vraie grandeur. Ces taux de production,
exprimés sous forme de masse de composant d’effluents par masse de combustible consommé, sont
ensuite reportés dans un modèle de mécanique des fluides, qui estime la vitesse de consommation du
combustible, le transport et la dilution des effluents dans l’ensemble du bâtiment au fur et à mesure de
l’évolution du feu.
Pour que l’analyse technique produise des résultats précis, il est nécessaire que les taux de production
soient déterminés à partir d’un appareillage dont il a été démontré qu’il produisait des taux de
production comparables à ceux obtenus lorsque la totalité du produit est brûlée. En plus de dépendre de
la composition chimique, de la conformation et des propriétés physiques de l’éprouvette d’essai, les taux
de production en produits toxiques sont sensibles aux conditions de combustion dans l’appareillage.
Par conséquent, l’une des solutions pour augmenter la probabilité d’obtenir des taux de production
précis à partir d’un appareillage d’essai au banc consiste à reproduire des conditions de combustion
similaires à celles attendues lors de la combustion du produit dans des conditions réelles. Comme
décrit dans l’ISO 19706, les principales conditions incluent la présence ou l’absence d’une flamme
lors de la combustion, le degré d’extension de la flamme, le rapport d’équivalence combustible/air et
l’environnement thermique. De même, il convient de déterminer ces paramètres pour un essai au feu en
vraie grandeur.
Les taux de production en gaz toxiques, l’efficacité de combustion et le rapport d’équivalence sont
susceptibles d’être sensibles à la manière dont l’éprouvette d’essai est prélevée dans le produit
commercial global. Des difficultés peuvent apparaître ou des méthodes alternatives peuvent être
utilisées pour obtenir une éprouvette d’essai adaptée. Le présent document ne traite pas de ces
difficultés ou méthodes alternatives et suppose qu’une éprouvette a été choisie pour l’étude et la
caractérisation des conditions de combustion ainsi que les taux de production des espèces chimiques
dans les effluents pour cette éprouvette.
Pour les feux expérimentaux pour lesquels des données résolues dans le temps sont disponibles, il
convient d’utiliser les méthodes exposées dans le présent document pour déterminer des valeurs
instantanées ou moyennes. L’application peut varier en fonction des changements dans la composition
chimique de l’éprouvette d’essai au cours de la combustion. Pour les essais au feu limités à la production
de concentrations en gaz dont la moyenne est établie dans le temps, les valeurs calculées en utilisant les
méthodes du présent document se limitent également à des moyennes. Dans les feux réels, les conditions
de combustion, la composition chimique du combustible et la composition des effluents du feu issus de
nombreux matériaux et produits communs varient en permanence pendant l’évolution du feu. Ainsi, la
précision avec laquelle les taux de production moyens obtenus par ces méthodes correspondent à ceux
d’un feu réel donné dépend fortement de la phase d’incendie, de la vitesse de développement du feu et
de la nature chimique des matériaux et produits exposés.
vi © ISO 2018 – Tous droits réservés
Le présent document donne des définitions et des équations permettant de calculer les taux de
production en produits toxiques et les conditions de combustion dans lesquelles ces taux de production
ont été déterminés en termes de rapport d’équivalence et d’efficacité de combustion. Des exemples
pratiques de calculs sur éprouvettes sont également fournis.
NORME INTERNATIONALE ISO 19703:2018(F)
Production et analyse des gaz toxiques dans le feu —
Calcul des taux de production des espèces, des rapports
d'équivalence et de l'efficacité de combustion dans les feux
expérimentaux
1 Domaine d’application
Le présent document donne des définitions et des équations permettant de calculer les taux de
production en produits toxiques et les conditions de combustion dans lesquelles ces taux de production
ont été déterminés en termes de rapport d’équivalence et d’efficacité de combustion. Des exemples
pratiques de calculs sur éprouvettes sont également fournis. Les méthodes exposées sont destinées à
être utilisées pour produire des valeurs instantanées ou moyennes pour les feux expérimentaux dans
lesquels des données en fonction du temps sont disponibles.
Le présent document a pour but de fournir des lignes directrices aux chercheurs du domaine de la lutte
contre l’incendie, afin:
— d’enregistrer des données appropriées relatives aux feux expérimentaux;
— de calculer les taux de production moyens en gaz et en fumée dans les effluents pendant les essais
au feu et dans des conditions de combustion analogues à celles d’un incendie sur un appareillage à
échelle réduite; et
— de caractériser les conditions de combustion dans les feux expérimentaux en termes de rapport
d’équivalence et d’efficacité de combustion, en utilisant les caractéristiques de consommation
d’oxygène et de génération de produits.
Le présent document ne fournit aucune ligne directrice sur le mode opératoire d’un appareil spécifique
ou sur l’interprétation des données acquises (interprétation toxicologique des résultats, par exemple).
2 Références normatives
Les documents suivants cités dans le texte constituent, pour tout ou partie de leur contenu, des
exigences du présent document. Pour les références datées, seule l’édition citée s’applique. Pour les
références non datées, la dernière édition du document de référence s'applique (y compris les éventuels
amendements)
ISO 13943, Sécurité au feu — Vocabulaire
3 Termes et définitions
Pour les besoins du présent document, les termes et définitions donnés dans l’ISO 13943 ainsi que les
suivants s’appliquent.
L’ISO et l’IEC tiennent à jour des bases de données terminologiques destinées à être utilisées en
normalisation, consultables aux adresses suivantes:
— IEC Electropedia: disponible à l’adresse http: //www .electropedia .org/
— ISO Online browsing platform: disponible à l’adresse http: //www .iso .org/obp
3.1
concentration massique de gaz
masse de gaz par volume unitaire
Note 1 à l'article: La concentration massique de gaz doit être déterminée à partir de la fraction volumique
mesurée et sa masse molaire, ou mesurée directement.
Note 2 à l'article: La concentration massique est généralement exprimée en grammes par mètre cube.
3.2
concentration massique en particules
masse des particules aérosols solides et liquides par volume unitaire
Note 1 à l'article: La concentration massique en particules est généralement exprimée en grammes par mètre cube.
3.3
masse molaire
masse de 1 mole
Note 1 à l'article: La masse molaire est normalement exprimée en grammes par mole.
3.4
régénération d’un élément
〈en un produit de combustion spécifié〉 degré de conversion d’un élément dans l’éprouvette d’essai en un
gaz correspondant
Note 1 à l'article: Il s’agit du rapport entre le taux de production réel et le taux de production théorique du gaz
contenant cet élément
3.5
masse atomique relative
masse moyenne d’un atome d’un élément divisée par un douzième de la masse d’un atome de carbone
(isotope C)
3.6
rapport stœchiométrique de masse oxygène-combustible
quantité d’oxygène dont a besoin un matériau pour réaliser une combustion complète
Note 1 à l'article: Le rapport stœchiométrique de masse oxygène-combustible est généralement exprimé en
grammes d’oxygène par gramme ou kilogramme de matériau brûlé.
3.7
incertitude
incertitude de mesure
paramètre associé au résultat d’une mesure, caractérisant la dispersion des valeurs qui pourraient être
attribuées raisonnablement à la mesure
Note 1 à l'article: La description et la propagation de l’incertitude de mesure sont décrites dans le Guide ISO/
[24]
IEC 98-3 .
[SOURCE: Guide ISO/IEC 98-3:2008, 2.2.3, modifié — Le terme a été modifié, «incertitude (de mesure)»
a été remplacé par «incertitude» et «incertitude de mesure» a été ajouté en tant que terme toléré; les
Notes 1, 2 et 3 à l’article d’origine ont été supprimées et une nouvelle Note 1 à l’article a été ajoutée.]
3.8
incertitude élargie
grandeur définissant un intervalle, autour du résultat d’un mesurage, dont on puisse s’attendre à ce
qu’il comprenne une fraction élevée de la distribution des valeurs qui pourraient être attribuées
raisonnablement à la mesure
Note 1 à l'article: Adapté du Guide ISO/IEC 98-3:2008, 2.3.5.
2 © ISO 2018 – Tous droits réservés
4 Symboles et unités
Tableau 1 — Symboles
Symbole Grandeur Unité typique
A surface d’extinction de la fumée mètre carré
A ou A surface d’extinction spécifique de la fumée par masse unitaire de mètre carré par gramme
σf SEA
matériau brûlé ou mètre carré par kilo-
gramme
D densité optique massique (équivalent log de A ) mètre carré par gramme
MO 10 SEA
ou mètre carré par kilo-
gramme
F fraction régénérée de l’élément E dans le gaz contenant E sans dimension
R,E
ΔH dégagement de chaleur mesuré pendant la combustion kilojoule par gramme
act
ΔH pouvoir calorifique inférieur ou enthalpie générée pendant la com- kilojoule par gramme
c
bustion complète
I/I fraction de lumière transmise à travers la fumée sans dimension
o
L trajet de la lumière à travers la fumée mètre
m masse atomique relative de l’élément E sans dimension
A,E
m fraction massique de l’élément E dans le matériau sans dimension
E
m masse du combustible gramme
fuel
m masse totale du gaz étudié gramme
gas
m perte de masse totale du matériau gramme
m,loss
vitesse de perte de masse du matériau gramme par minute
m
m,loss
m masse réelle d’oxygène disponible pour la combustion gramme
O,act
débit massique réel de l’oxygène disponible pour la combustion gramme par minute
m
O,act
m masse stœchiométrique d’oxygène nécessaire pour la combustion gramme
O,stoich
complète
m masse totale des particules gramme
part
M masse molaire du gaz étudié gramme par mole
gas
M masse molaire de l’unité polymère gramme par mole
poly
n nombre d’atomes de l’élément E dans une molécule de gaz sans dimension
E
n nombre d’atomes de l’élément E dans l’unité polymère sans dimension
E,poly
P pression ambiante kilopascal
amb
P pression normalisée 101,3 kPa
std
T température thermodynamique du gaz étudié au point de mesure kelvin
C
V volume de la chambre mètre cube
V volume total des effluents du feu mètre cube
eff
débit volumique d’air mètre cube par minute
V
air
w fraction massique mesurée de l’oxygène consommé par masse uni- sans dimension
O,cons
taire de combustible
w fraction massique dérivée de l’oxygène consommé par masse uni- sans dimension
O,der
taire de combustible
w fraction massique d’oxygène dans le polymère, contribuant à la for- sans dimension
Oex,poly
mation de produits contenant de l’oxygène
w fraction massique d’oxygène consommé sous la forme des principaux sans dimension
O,gases
produits contenant de l’oxygène (w + w + w )
O,CO2 O,CO O,H2O
w fraction massique d’oxygène dans le polymère sans dimension
O,poly
Y taux de production massique mesuré du gaz étudié sans dimension
gas
Tableau 1 (suite)
Symbole Grandeur Unité typique
Y taux de production massique mesuré des particules de fumée sans dimension
part
α coefficient décimal d’absorption linéaire (ou densité optique) mètre inverse
α coefficient d’extinction de la lumière mètre inverse
k
χ efficacité de combustion sans dimension
χ efficacité de combustion calculée à partir du taux d’efficacité de sans dimension
cox
génération d’oxydes de carbone à partir du carbone du combustible
χ O efficacité de combustion calculée à partir de l’appauvrissement en sans dimension
oxygène
χ efficacité de combustion calculée à partir de l’oxygène présent dans sans dimension
prod
les produits de combustion majeurs
ϕ rapport d’équivalence sans dimension
η taux d’efficacité de génération des oxydes de carbone sans dimension
φ fraction volumique du gaz étudié sans dimension
gas
φ fraction volumique de l’oxygène dans l’alimentation en air (0,209 5 sans dimension
O
pour l’air sec)
ρ concentration massique du gaz étudié gramme par mètre cube
gas
ρ concentration de perte de masse du matériau gramme par mètre cube
m,loss
ρ concentration massique réelle de l’oxygène disponible pour la gramme par mètre cube
O,act
combustion
ρ concentration massique des particules de fumée gramme par mètre cube
part
σ coefficient d’extinction spécifique massique mètre carré par gramme
m,α
ou mètre carré par kilo-
gramme
Ψ taux de production (fraction massique) théorique du gaz étudié sans dimension
gas
Ψ rapport stœchiométrique de masse oxygène-combustible sans dimension
O
5 Données d’entrée appropriées pour les calculs
5.1 Traitement des données
5.1.1 Incertitude
Pour calculer les paramètres de combustion décrits dans le présent document, il doit être tenu compte
de l’incertitude ou de l’erreur associée à chaque composant et elles doivent être combinées de manière
[1]
correcte. L’incertitude dérive de l’exactitude (c’est-à-dire la justesse de l’accord entre la valeur
mesurée et la valeur réelle) et de la fidélité (c’est-à-dire l’accord entre les différentes valeurs). Des
incertitudes apparaîtront sur les paramètres mesurés physiquement (par exemple la perte de masse et
les concentrations en gaz).
En supposant que toutes les erreurs sont indépendantes, l’erreur totale, δq, est obtenue en ajoutant les
carrés des erreurs conformément à la Formule (1) générale:
δq δq
δq= δa ++. δz (1)
δa δz
En d’autres termes, évaluer l’erreur due à chacune des mesures individuelles, puis combiner les erreurs
en calculant la racine de la somme des carrés.
4 © ISO 2018 – Tous droits réservés
Dans les équations établies de manière empirique, les incertitudes dans les valeurs «constantes»
doivent être traitées comme des incertitudes de mesure. Si une constante est réellement constante,
c’est-à-dire que son incertitude est négligeable, elle peut être négligée.
5.1.2 Chiffres significatifs et arrondi
Lors de l’enregistrement des données et de la production de rapports, il est nécessaire de traiter
correctement les chiffres significatifs. L’approche générale consiste à conserver un chiffre au-delà
du dernier chiffre certain. Pour l’arrondi, la règle typique est d’arrondir par excès lorsque le chiffre à
arrondir est supérieur ou égal à 5, et d’arrondir par défaut lorsqu’il est inférieur à 5.
5.2 Information sur les éprouvettes d’essai
5.2.1 Composition
Dans la mesure du possible, il est nécessaire de donner des informations sur la fraction combustible,
les composants combustibles organiques et inorganiques, les composants inertes, la composition
élémentaire, la formule empirique et le poids moléculaire ou formulaire.
Dans un feu expérimental où le combustible est un seul matériau homogène, contenant éventuellement
des additifs dispersés, la formule moléculaire du matériau doit être précisée. En revanche, les produits
commerciaux sont généralement des combinaisons non homogènes de matériaux dont chaque
composant contient un ou plusieurs polymères et éventuellement plusieurs additifs. Pour les matériaux
complexes représentatifs de produits commerciaux, les taux de production, les chaleurs de combustion
effectives, etc., varient en fonction du temps, au fur et à mesure que les différents composants sont
impliqués dans la combustion. Pour certains des calculs suivants (globaux), une méthode simplifiée
consiste à utiliser une formule empirique pour le composite.
5.2.2 Pouvoir calorifique inférieur
Le pouvoir calorifique inférieur des composants combustibles doit être nécessaire pour certains calculs
(efficacité de combustion, par exemple).
5.3 Conditions de combustion
5.3.1 Appareillage
Indiquer le nom de l’appareil et décrire brièvement son mode opératoire (par exemple état d’écoulement
stable, calorimètre, système à chambre fermée). Préciser la norme appropriée ou toute autre référence
liée au mode opératoire.
5.3.2 Mode opératoire de réglage
Les conditions de combustion dépendent généralement de l’appareil et sont influencées en grande
partie par le mode opératoire de réglage de l’appareil particulier. Les informations suivantes doivent
être fournies:
a) les détails de l’éprouvette d’essai, sa masse, ses dimensions et l’orientation du combustible;
b) l’environnement thermique en termes de température (exprimée en degrés Celsius) et de
rayonnement calorifique (exprimé en kilowatts par mètre carré) auquel l’éprouvette d’essai est
soumise;
NOTE Les champs de température et de rayonnement d’un essai ne sont généralement pas uniformes
et sont donc rarement bien documentés. Le fait de fournir suffisamment d’informations sur les conditions
de température et de rayonnement permet d’assurer qu’une autre personne puisse reproduire les résultats
en utilisant le même appareil, comparer les résultats avec ceux obtenus pour la même éprouvette soumise à
essai dans un autre appareil, etc.
c) la concentration en oxygène dans l’alimentation en air (pourcentage en volume ou fraction
volumique);
d) le volume de la chambre ou le débit d’air. Pour un système fermé, indiquer le volume d’air (exprimé
en litres ou en mètres cubes) et, pour un système ouvert, préciser le débit d’air (exprimé en litres
par minute ou en mètres cubes par minute) et les paramètres dynamiques de l’écoulement. Dans
les deux cas, donner des informations sur les conditions de mélange atmosphérique et sur le degré
d’homogénéité des effluents du feu.
5.4 Collecte des données
5.4.1 Acquisition des données
Il est possible d’acquérir des données en fonction du temps ou intégrées dans le temps. Il est nécessaire
de préciser la méthode d’acquisition des données dans le mode opératoire d’essai.
5.4.2 Données mesurées et observations
Il est nécessaire d’utiliser la plupart des paramètres suivants pour calculer les taux de production, les
rapports d’équivalence et les efficacités de combustion dans les feux expérimentaux. En règle générale,
il convient que les unités appliquées aux données soient dictées par le mode opératoire associé à un
appareil particulier. Plusieurs unités typiques sont suggérées:
a) la perte de masse de l’éprouvette d’essai, déduite en mesurant la masse de l’éprouvette avant et
après l’essai pour obtenir la perte de masse totale (exprimée en milligrammes, en grammes ou en
kilogrammes) ou la fraction de perte de masse (exprimée en pourcentage en masse, en grammes
par gramme ou en kilogrammes par kilogramme), ou en mesurant la masse de l’éprouvette tout
au long d’un essai pour déterminer la vitesse de perte de masse (exprimée en milligrammes par
seconde, en grammes par minute ou en kilogrammes par minute);
b) les concentrations en gaz et en vapeur et l’appauvrissement en oxygène (exprimés en pourcentage
en volume, en fraction volumique, en microlitres par litre, en milligrammes par litre ou en
milligrammes par mètre cube);
c) la concentration en particules de fumée (exprimée en milligrammes par litre ou en milligrammes
par mètre cube) et l’obscurcissement par la fumée (exprimé en densité optique par mètre ou en
mètres carrés par kilogramme);
d) le dégagement de chaleur (exprimé en kilojoules par gramme), servant à calculer l’efficacité de
combustion et formant une partie du mode opératoire de certains appareils;
e) le mode de combustion, le délai d’allumage (exprimé en minutes ou en secondes) et l’inflammation
ou non de l’éprouvette tout au long de l’essai.
6 © ISO 2018 – Tous droits réservés
6 Calcul des taux de production des gaz de combustion et de la fumée, du
rapport stœchiométrique de masse oxygène-combustible et de la régénération
des principaux éléments
6.1 Calcul des taux de production mesurés à partir des données sur la concentration en
gaz de combustion
Dans les feux expérimentaux, le taux de production massique d’un gaz, Y , doit être calculé à partir
gas
de la concentration massique mesurée du gaz présentant un intérêt et de la concentration de perte de
masse du matériau, conformément à la Formule (2) (voir les NOTES 1, 2 et 3):
ρ
gas
Y = (2)
gas
ρ
m,loss
où
ρ est la concentration massique du gaz;
gas
ρ est la concentration de perte de masse du matériau.
m,loss
En variante, Y doit être calculé à partir de la masse totale de gaz produite et de la perte de masse
gas
totale du matériau, conformément à la Formule (3):
m
gas
Y = (3)
gas
m
m,loss
où
m est la masse totale du gaz;
gas
m est la perte de masse totale du matériau.
m,loss
NOTE 1 Ces calculs peuvent être dérivés de données instantanées ou de données qui supposent que les gaz
sont uniformément dispersés dans un certain volume et que ce volume est celui dans lequel la masse d’éprouvette
perdue est (uniformément) dispersée. Si la dispersion n’est pas uniforme, les équations continueront à être
valides si la masse perdue et le gaz en question sont dispersés en quantités équivalentes. Si un gaz de combustion
est sujet à des pertes superficielles à l’intérieur de l’appareil, le taux de production apparent dépend de l’endroit
où est mesurée la concentration.
NOTE 2 Dans les dispositifs à débit continu, tous les effluents sont généralement bien mélangés à une certaine
distance en aval. Pour les systèmes de combustion à chambre fermée, il est possible que ce mélange ne soit pas
effectué, en particulier si les différences de poids moléculaire et les gradients thermiques sont importants. Si la
combustion implique plusieurs combustibles, seul un taux de production combiné moyen peut être calculé.
NOTE 3 Lors de ces calculs, des incertitudes apparaîtront pour ce qui concerne la masse d’éprouvette perdue,
les fluctuations de la concentration mesurée, etc.
Il est nécessaire de contrôler ces incertitudes. Le taux de production calculé doit tenir compte de ces
incertitudes et les combiner afin d’établir une base solide pour comparer les taux de production dans
différentes conditions de combustion, pour comparer les taux de production de différents matériaux, et
ainsi de suite.
Bien que les concentrations en gaz spécifique soient le plus souvent mesurées en fractions volumiques,
les Formules (4) et (5) permettent de convertir la fraction volumique d’un gaz en concentration
massique:
M
273,15K P
gas
amb
ρϕ=× ×× (4)
gasgas
31−
T 101,325kPa
22,414dm ⋅mol
C
où
ρ est la concentration massique du gaz;
gas
φ est la fraction volumique du gaz;
gas
M est la masse molaire du gaz;
gas
T est la température thermodynamique du gaz au point de mesure;
C
P est la pression ambiante;
amb
273,15 K est la température thermodynamique normalisée;
101,325 kPa est la pression normalisée;
3 −1
22,414 dm ⋅mol est le volume molaire d’un gaz parfait aux température et pression normalisées.
Par conséquent, pour les effluents du feu à 20 °C et sous une pression normalisée, la Formule (4) se
simplifie et devient la Formule (5):
M
gas
ρϕ=× (5)
gasgas
31−
24,055dm ⋅mol
EXEMPLE Pour une atmosphère de combustion bien ventilée, où la concentration de perte de masse du
−3
matériau est égale à 25 g⋅m et la fraction volumique de monoxyde de carbone (CO) est de 0,125 % (ou 0,001 25)
à 20 °C, les calculs sont donnés par les Formules (6) et (7):
−1
28,01gm⋅ ol
−3 −3
ρ =×0,00125 =⋅0,,001456gdm =14556gm⋅ (6)
CO
31−
24,055dm ⋅mol
−−33
Y =⋅1,/456gm 25⋅=m 0,0582 (7)
co
où
ρ est la concentration massique en CO;
CO
Y est le taux de production massique de CO (masse de CO par masse unitaire de
CO
matériau);
−1
28,01 g⋅mol est la masse molaire du CO.
Les Tableaux 2 et 3 indiquent les masses atomiques relatives, les masses molaires et les facteurs de
conversion des concentrations des principaux gaz de combustion.
8 © ISO 2018 – Tous droits réservés
[2]
Tableau 2 — Masse atomique relative des principaux éléments des gaz de combustion
a
Élément Symbole Masse atomique relative
Carbone C 12,011
Hydrogène H 1,0079
Oxygène O 15,999
Azote N 14,007
Chlore Cl 35,453
Brome Br 79,904
Fluor F 18,998
Soufre S 32,065
Phosphore P 30,973
Antimoine Sb 121,76
a
Valeurs de masse atomique relative arrondies à cinq chiffres significatifs.
Tableau 3 — Masses molaires des gaz de combustion courants et facteurs de conversion des
fractions volumiques/concentrations massiques
Gaz ou vapeur Formule Masse Facteurs de conversion des concentrations en gaz
a
molaire (à 20 °C et 101,3 kPa)
−1
g·mol
Pour convertir une fraction Pour convertir une concen-
volumique en concentration, tration en fraction volumique,
multiplier par la masse volu- diviser par la masse volu-
mique du gaz: mique du gaz:
−3
Dioxyde de carbo- CO 44,01 1 830 g.m
b
ne
−3
Monoxyde de car- CO 28,01 1 164 g.m
b
bone
−3
Cyanure d’hydro- HCN 27,02 1 124 g.m
gène
−3
Dioxyde d’azote NO 46,01 1 913 g.m
−3
Monoxyde de N O 44,01 1 831 g.m
diazote
−3
Monoxyde d’azote NO 30,01 1 248 g.m
−3
Ammoniac NH 17,03 708 g.m
−3
Chlorure d’hydro- HCl 36,46 1 516 g.m
gène
−3
Bromure d’hydro- HBr 80,91 3 364 g.m
gène
−3
Fluorure d’hydro- HF 20,01 832 g.m
gène
−3
Sulfure d’hydro- H S 34,08 1 417 g.m
gène
−3
Dioxyde de soufre SO 64,06 2 663 g.m
−3
Eau H O 18,01 749 g.m
−3
Acide phospho- H PO 97,99 4 074 g.m
3 4
rique
−3
Acroléine C H O 56,06 2 331 g.m
3 4
Tableau 3 (suite)
Gaz ou vapeur Formule Masse Facteurs de conversion des concentrations en gaz
a
molaire (à 20 °C et 101,3 kPa)
−1
g·mol
Pour convertir une fraction Pour convertir une concen-
volumique en concentration, tration en fraction volumique,
multiplier par la masse volu- diviser par la masse volu-
mique du gaz: mique du gaz:
−3
Formaldéhyde CH O 30,03 1 248 g.m
−3
Oxygène O 32,00 1 331 g.m
NOTE La concentration en gaz est égale à la fraction volumique x la masse volumique.
Exemple de calculs:
4 −3 −3
Si φ = 0,01 (c’est-à-dire 1 % ou 10 μl/l), m = 0,01 × 1 164 g⋅m = 11,64 g⋅m .
CO CO
−3 −3 −3
Si m = 0,281 g⋅m , φ = 0,281 g⋅m /1 124 g⋅m = 0,000 25 (c’est-à-dire 0,025 % ou 250 μl/l).
HCN HCN
a
Les valeurs de masse molaire sont arrondies à deux décimales.
b
Le rapport de volume CO /CO est égal au rapport de masse CO /CO divisé par 1,571.
2 2
6.2 Calcul des taux de production théoriques des gaz
6.2.1 Généralités
Les taux de production théoriques des gaz et des vapeurs permettent de déterminer les taux de
production théoriques maximaux des produits de combustion. Ils sont basés sur la composition du
matériau et dépendent entièrement de ce dernier. Deux principales options de calcul sont décrites
en 6.2.2 et en 6.2.3.
6.2.2 Calcul à partir de la composition élémentaire
Pour autant que la composition élémentaire du matériau de base soit connue (par analyse élémentaire,
par exemple), le taux de production (théorique) maximal du gaz de combustion, Ψ , correspondant à
gas
chaque élément spécifié, E, est calculé en utilisant la Formule (8):
M
gas
Ψ =×m (8)
gasE
nm×
EA,E
où
m est la fraction massique de l’élément E dans le matériau;
E
M est la masse molaire du gaz considéré;
gas
n est le nombre d’atomes de l’élément E dans une molécule du gaz;
E
m est la masse atomique relative de l’élément E;
A,E
10 © ISO 2018 – Tous droits réservés
EXEMPLE Le taux de production théorique du CO, Ψ , à partir de la cellulose, (C H O ) , est calculé à l’aide
CO 6 10 5 n
de la Formule (9):
−1
28,01gm⋅ ol
Ψ =×0,445 =1,038 (9)
CO
−1
11×⋅2,011gmol
où
0,445 est la fraction massique de carbone dans la cellulose;
−1
28,01 g⋅mol est la masse molaire du CO;
1 est le nombre d’atomes de carbone dans une molécule de CO;
−1
12,011 g⋅mol est la masse molaire du carbone.
Le Tableau 4 indique les facteurs permettant de calculer les taux de production théoriques des gaz à
M
gas
partir de la composition élémentaire et déduits du terme de la Formule (8).
nm×
EA,E
Tableau 4 — Facteurs permettant de calculer les taux de production théoriques des gaz à partir
de la composition élémentaire du matériau
a
Gaz ou vapeur Élément E considéré dans le Facteur
matériau de base
Formule Masse
molaire
g⋅mol-1
CO 44,01 carbone 3,664
CO 28,01 carbone 2,332
H O 18,02 hydrogène 8,939
HCN 27,02 azote 1,929
NO 46,01 azote 3,284
N O 44,01 azote 1,571
NO 30,01 azote 2,142
NH 17,03 azote 1,216
HCl 36,46 chlore 1,028
HBr 80,92 brome 1,013
HF 20,01 fluor 1,053
H S 34,08 soufre 1,063
H PO 97,98 phosphore 3,163
3 4
SO 64,06 soufre 1,998
Acroléine (C H O) 56,06 carbone 1,556
3 4
Formaldéhyde 30,03 carbone 2,500
(CH O)
M
gas
a
Facteur arrondi à quatre chiffres significatifs.
nm×
EA,E
6.2.3 Calcul à partir de la formule empirique
Si la formule empirique du matériau est connue, il est nécessaire de calculer le taux de production
théorique, Ψ , à l’aide de la Formule (10):
gas
n M
E,poly gas
Ψ =× (10)
gas
n M
E poly
où
n est le nombre d’atomes de l’élém
...
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