ISO/TS 12828-3:2024

Technical
Specification
ISO/TS 12828-3
Second edition
Validation method for fire gas
2024-11
analysis —
Part 3:
Considerations related to
interlaboratory trials
Méthode de validation des analyses de gaz d'incendie —
Partie 3: Considérations relatives aux essais interlaboratoires
Reference number
© ISO 2024
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 General considerations . 3
5.1 Trueness and fidelity .3
5.1.1 General .3
5.1.2 Trueness .3
5.1.3 Fidelity (precision) .4
5.1.4 Summary .5
5.2 Deviation sources independent from analytical technique .5
5.2.1 Deviation sources from the material or product tested .5
5.2.2 Deviation sources from the physical fire model used .5
5.3 Deviation sources due to analytical technique .6
6 Different kinds of interlaboratory trials . 6
6.1 Sources of error .6
6.2 Fire model, sampling, conditioning and analysis .6
6.3 Analysis alone.7
6.4 Comparison between techniques . . .7
Annex A (informative) Examples of application . 8
Bibliography .11

iii
Foreword
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The procedures used to develop this document and those intended for its further maintenance are described
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This document was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 3, Fire threat
to people and environment.
This second edition cancels and replaces the first edition (ISO/TS 12828-3:2020), which has been technically
revised.
The main changes are as follows:
— Clause 1, 5.1.2, and 6.4 have been updated to clarify confusion between repeatability and reproducibility;
— minor editorial changes have been made throughout the document.
A list of all parts in the ISO 12828 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
The reduction of human tenability from fire effluent has long been recognized as a major cause of injury
and death in fire. The composition and concentration of the effluent from a large fire are also clearly key
factors in determining the potential for harm to the environment. The harmful components of fire effluent
can be determined from both large- and small-scale tests of materials and finished products. Formulae have
been developed for quantifying the effects of the effluent components, in order to estimate the available safe
[1]
escape time (ASET), for example. Related documents are also being developed by ISO/TC 92/SC 3 which
deal with environmental threats from fire effluent.
These advances in fire science and fire safety engineering have led to an increasing demand for quantitative
measurements of the chemical components of the fire effluent. The characterization of these measurements
is described in ISO 12828-2. This document describes the how to compare results from one laboratory to
another and how to obtain a global confidence in any measurement technique, independent of the user and
the conditions of use.
This document complements ISO 12828-1, which deals with limits of quantification and detection, and
ISO 12828-2, which deals with intralaboratory validation of analytical methods. It is a useful toolbox within
the framework of ISO/IEC 17025 assessment of any fire laboratory.
Examples of existing standards where the information contained in this document can be used are the
analytical chemical methods in ISO 19701, ISO 19702, ISO 5660-1, and the chemical measurements in
the methods discussed in ISO/TR 16312-2, ISO 16405, ISO/TS 19021, or their application to fire toxicity
assessment using ISO 13571 and ISO 13344.

v
Technical Specification ISO/TS 12828-3:2024(en)
Validation method for fire gas analysis —
Part 3:
Considerations related to interlaboratory trials
1 Scope
This document describes techniques and gives guidance concerning interlaboratory trials related to
fire effluent analyses. It explains the relative contributions from the physical fire model and analytical
techniques to evaluate trueness and fidelity. It also explains the difficulties involved in the interpretation of
interlaboratory trials data and with the evaluation of trueness in fire effluent analyses.
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 472, Plastics — Vocabulary
ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General
principles and definitions
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for
the determination of repeatability and reproducibility of a standard measurement method
ISO 12828-2, Validation method for fire gas analysis — Part 2: Intralaboratory validation of quantification methods
ISO 13943, Fire safety — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 5725-1, ISO 13943, ISO 472 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
accuracy
closeness of agreement between a measured quantity value and a true quantity value of a measurand
[SOURCE: ISO/IEC Guide 99:2007, 2.13, modified — Note 1 to entry and Note 3 to entry have been removed.]
3.2
k-score
score that characterizes the fidelity of a laboratory
Note 1 to entry: The k-score is defined according to the following formula:

s
w
k =
i
s
r
where
k is the k-score of the laboratory i;
i
s is the within-laboratory standard deviation for the laboratory i;
w
s is the estimate of the repeatability standard deviation.
r
3.3
precision
closeness of agreement between indications or measured quantity values obtained by replicate
measurements on the same or similar objects under specified conditions
[SOURCE: ISO/IEC Guide 99:2007, 2.15, modified — Note 1 to entry and Note 4 to entry have been removed.]
3.4
trueness
closeness of agreement between the average of an infinite number of replicate measured quantity values
and a reference quantity value
[SOURCE: ISO/IEC Guide 99:2007, 2.14, modified — Note 1 to entry and Note 3 to entry have been removed.]
3.5
z-score
score that characterizes the bias and thus the trueness (3.4) of a laboratory, assuming the real value is the
general mean and the real dispersion is the overall standard deviation s
Note 1 to entry: The z-score is defined according to the following formula:
ym−
i
z =
i
s
where
z is the z-score of the laboratory i;
i
y
is the mean value from laboratory i;
i
m is the general mean, sometimes expressed as the level of the test;
s is the overall standard deviation.
4 Symbols
b laboratory component of bias under repeatability conditions
e random error occurring in repeatability conditions
k k-score, estimate of the fidelity of the laboratory i
i
m general mean, sometimes expressed as the level of the test
n number of laboratories
i
s overall standard deviation
s between-laboratory standard deviation
L
s estimate of the repeatability standard deviation
r
s estimate of the reproducibility standard deviation
R
s within-laboratory standard deviation for the laboratory i
w
y mean value from laboratory i
i
mean value from all laboratories
y
i
z z-score, estimate of the trueness of the laboratory i
i
5 General considerations
5.1 Trueness and fidelity
5.1.1 General
A test result is described by the model y = m + b + e. In this expression, the measured value is the real value
affected by the bias (trueness error) and the random error (fidelity error). Annex A presents a compilation of
data of trueness and fidelity obtained from different standards.
5.1.2 Trueness
5.1.2.1 Overview
In the context of fire effluent analysis, trueness is the correspondence between the real (theoretical) value
of an analyte and the measured value (see ISO 19703). Depending on the existence and knowledge of the
real value, bias b, characterizing trueness, is sometimes partially characterized by z-score. Bias expresses
the deviation to a real value, whereas z-score supposes that the general mean corresponds to the real value.
This latter assumption is questionable in several cases for fire gases analysis. The z-score can be interpreted
as follows:
— z ≤ 2 means that the trueness performance of the laboratory is in the 95 % range of more probable values;
i
— 23<≤z means that the trueness performance of the laboratory is suspect, in the range of the next
i
4,7 % less probable values;
— z > 3 means that the trueness performance of the laboratory is unsatisfactory, in the range of the
i
remaining 0,3 % of the least probable values.
5.1.2.2 Case 1 – Physical fire model included in fire gas analysis
The general principle is the combustion of standard materials followed by a mass balance calculation. A real
value can be assumed and the bias can be calculated for several mass balances, including:
— halogenated acids, assuming 100 % mol/mol of halogen in the initial material is converted into
hydrogen halide;
— carbon, considering CO , CO and other carbonaceous compounds represent the large majority of carbon
initially present, preferably in well ventilated conditions;
— sulfur released as SO in well-ventilated conditions (stage 2, according to ISO 19706).
This kind of mass balance corresponds to a global validation of trueness and fidelity, considering errors due
to the fire model itself and those from the analysis, as they cannot be dissociated. It is not possible to do such
mass balance calculation with some other elements such as nitrogen.
5.1.2.3 Case 2 – Physical fire model excluded from fire gas analysis
In this case, two situations are possible.

— Sub-case 2a): Use of standard gases injected at the point of emission in normal use, e.g. at the location of
the material in combustion tests. This checks the trueness and fidelity of the sampling and analysis, but
not the possible variation due to the combustion process itself.
— Sub-case 2b): Use of standard gases or standard solutions (see ISO 12828-1) in realistic matrix. This
checks the trueness and fidelity of the analysis.
5.1.2.4 Example – Cases where the theoretical value is known
The analyte studied is hydrogen chloride. The analytical method is high performance ion chromatography
according to ISO 19701:2013, 5.5.2. Determine the trueness of the method.
— Case 1): Unmodified PVC is burnt according to an appropriate fire model. Suitable solution traps are used
to capture the hydrogen chloride gas from the effluent. The solution is then analysed. PVC comprises
56,8 % by mass of chlorine and the theoretical yield of HCl is 0,584 g/g.
— Cases 2a) and 2b): A known quantity of HCl gas is introduced at an appropriate point in the fire test
apparatus. For example, a flow of 0,5 L/min under standard pressure and at 20 °C at a volume fraction of
1 000 μL/L for a period of 5 min. This results in a theoretical quantity of 3,80 mg.
5.1.2.5 Example – Cases where the theoretical cannot be evaluated
— The analyte studied is nitrogen dioxide. The analytical method is chemiluminesce
...