Guidance for assessing the validity of physical fire models for obtaining fire effluent toxicity data for fire hazard and risk assessment — Part 1: Criteria

ISO 16312-1:2010 provides technical criteria and guidance for evaluating physical fire models (i.e. laboratory combustion devices and operating protocols) used in effluent toxicity studies for obtaining data on the effluent from products and materials under fire conditions relevant to life safety. Relevant analytical methods, calculation methods, bioassay procedures and prediction of the toxic effects of fire effluents can be referenced in ISO 19701, ISO 19702 [4], ISO 19703, ISO 19706, ISO 13344 and ISO 13571.

Lignes directrices pour évaluer la validité des modèles de feu physiques pour l'obtention de données sur les effluents du feu en vue de l'évaluation des risques et dangers — Partie 1: Critères

General Information

Status
Withdrawn
Publication Date
21-Feb-2010
Withdrawal Date
21-Feb-2010
Current Stage
9599 - Withdrawal of International Standard
Start Date
14-Nov-2016
Completion Date
14-Nov-2016
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INTERNATIONAL ISO
STANDARD 16312-1
Second edition
2010-03-01
Guidance for assessing the validity of
physical fire models for obtaining fire
effluent toxicity data for fire hazard and
risk assessment —
Part 1:
Criteria
Lignes directrices pour évaluer la validité des modèles de feu physiques
pour l'obtention de données sur les effluents du feu en vue de
l'évaluation des risques et dangers —
Partie 1: Critères
Reference number
ISO 16312-1:2010(E)
ISO 2010
---------------------- Page: 1 ----------------------
ISO 16312-1:2010(E)
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ii © ISO 2010 – All rights reserved
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ISO 16312-1:2010(E)
Contents Page

Foreword ............................................................................................................................................................iv

Introduction.........................................................................................................................................................v

1 Scope......................................................................................................................................................1

2 Normative references............................................................................................................................1

3 Terms and definitions ...........................................................................................................................1

4 General principles .................................................................................................................................1

5 Significance and use.............................................................................................................................2

6 The ideal fire effluent toxicity test method .........................................................................................2

7 Characteristics of fire stages ...............................................................................................................4

8 Characterization of physical fire models ............................................................................................4

9 Physical fire model accuracy ...............................................................................................................6

Annex A (informative) Characteristics affecting combustion product yields ..............................................9

Bibliography......................................................................................................................................................11

© ISO 2010 – All rights reserved iii
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ISO 16312-1:2010(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies

(ISO member bodies). The work of preparing International Standards is normally carried out through ISO

technical committees. Each member body interested in a subject for which a technical committee has been

established has the right to be represented on that committee. International organizations, governmental and

non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the

International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 16312-1 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 16312-1:2006), of which it constitutes a minor

revision, with the following modifications.
a) The normative and bibliographic references have been updated.

b) Individual terms and definitions have been removed from this part of ISO 16312 and replaced by a

reference to ISO 13943:2008, in which they now appear.

ISO 16312 consists of the following parts, under the general title Guidance for assessing the validity of

physical fire models for obtaining fire effluent toxicity data for fire hazard and risk assessment:

⎯ Part 1: Criteria
⎯ Part 2: Evaluation of individual physical fire models
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ISO 16312-1:2010(E)
Introduction

Providing the desired degree of life safety for an occupancy increasingly involves an explicit fire hazard or risk

assessment. This assessment includes such components as
⎯ information on the room/building properties;
⎯ the nature of the occupancy;
⎯ the nature of the occupants;
⎯ the types of potential fires;
⎯ the outcomes to be avoided, etc.

This type of determination also requires information on the potential for harm due to the effluent produced in

the fire. Because of the prohibitive cost of real-scale product testing under the wide range of fire conditions,

most estimates of the potential harm from the fire effluent depend on data generated from a physical fire

model, a reduced-scale test apparatus and procedure for its use.

The role of a physical fire model for generating accurate toxic effluent composition is to recreate the essential

features of the complex thermal and reactive chemical environment in full-scale fires. These environments

vary with the physical characteristics of the fire scenario and with time during the course of the fire, and close

representation of some phenomena occurring in full-scale fires can be difficult or even not possible on a

small-scale. The accuracy of the physical fire model, then, depends on two features:

a) degree to which the combustion conditions in the bench-scale apparatus mirror those in the fire stage

being replicated;

b) degree to which the yields of the important combustion products obtained from burning of the commercial

product at full scale are replicated by the yields from burning specimens of the product in the small-scale

model. This measure is generally performed for a small set of products, and the derived accuracy is then

presumed to extend to other test subjects. At least one methodology for effecting this comparison has

[1]
been developed .

This part of ISO 16312 provides guidance for accuracy assessment with and without the use of laboratory

animals. Generally, accurate estimation of the toxic potency of the effluent can be obtained from analysis of a

small number of gases (the N-gas hypothesis), as described in ISO 13571. This is especially true for product

formulations similar to those for which the N-gas model has been confirmed. There are, however, cases where

unusual toxicants have been generated in bench-scale apparatus. Thus, for novel commercial product

formulations, confidence in the accuracy of the toxic potency measurement in the bench-scale device can be

improved by a confirming bioassay and correlation with real-scale fire tests.
© ISO 2010 – All rights reserved v
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INTERNATIONAL STANDARD ISO 16312-1:2010(E)
Guidance for assessing the validity of physical fire models for
obtaining fire effluent toxicity data for fire hazard and risk
assessment —
Part 1:
Criteria
1 Scope

This part of ISO 16312 provides technical criteria and guidance for evaluating physical fire models (i.e.

laboratory combustion devices and operating protocols) used in effluent toxicity studies for obtaining data on

[2]

the effluent from products and materials under fire conditions relevant to life safety . Relevant analytical

methods, calculation methods, bioassay procedures and prediction of the toxic effects of fire effluents can be

[3] [4] [5] [6] [7]

referenced in ISO 19701 , ISO 19702 , ISO 19703 , ISO 19706 , ISO 13344 , and ISO 13571.

2 Normative references

The following referenced documents are indispensable for the application 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 13571:2007, Life-threatening components of fire — Guidelines for the estimation of time available for

escape using fire data
ISO 13943:2008, Fire safety — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 13943:2008 apply.

4 General principles
4.1 Physical fire model

A physical fire model is characterized by the requirements placed on the form of the test specimen, the

operational combustion conditions and the capability of analysing the products of combustion.

4.2 Model validity

For use in providing data for effluent toxicity assessment, the validity of a physical fire model is determined by

the degree of accuracy with which it reproduces the yields of the principal toxic components in real-scale fires.

© ISO 2010 – All rights reserved 1
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ISO 16312-1:2010(E)
4.3 Test specimens

Fire safety engineering requires data on commercial products or product components. In a reduced-scale test,

the manner in which a specimen of the product is composed can affect the nature and yields of the

combustion products.
4.4 Combustion conditions

The yields of combustion products depend on such apparatus conditions as the fuel/air equivalence ratio,

whether the decomposition is flaming or non-flaming, the persistence of flaming of the sample, the

temperature of the specimen and the effluent produced, the stability of the decomposition conditions, and the

interaction of the apparatus with the decomposition process, with the effluent and the flames.

4.5 Effluent characterization

4.5.1 For the effluent from most common materials, the major acute toxic effects have been shown to

depend upon a small number of major asphyxiant gases and a somewhat wider range of inorganic and

organic irritants. In ISO 13571, a base set of combustion products has been identified for routine analysis.

Novel materials can evolve previously unidentified toxic products. Thus a more detailed chemical analysis can

be needed in order to provide a full assessment of acute effects and to assess chronic or environmental

toxicants. A bioassay can provide guidance on the importance of toxicants not included in the base set.

[6]
ISO 19706 contains a fuller discussion of the utility of bioassays.

4.5.2 It is essential that the physical fire model enable accurate determinations of chemical effluent

composition.

4.5.3 It is desirable that the physical fire model accommodate a bioassay method.

5 Significance and use

5.1 Most computational models of fire hazard and risk require information regarding the potential of fire

effluent (gases, heat, and smoke) to cause harm to people and to affect their ability to escape or to seek

refuge.

5.2 The quality of the data on fire effluent has a profound effect on the accuracy of the prediction of the

degree of life safety offered by an occupancy design.

5.3 Due to the large number of products to be included in fire safety assessments, the high cost of

performing real-scale tests of products, and the small number of large-scale test facilities, information on

effluent toxicity is most often obtained from physical fire models.

5.4 There are numerous physical fire models cited in national regulations. These apparatus vary in design

and operation, as well as in their degree of characterization. This part of ISO 16312 defines what apparatus

characteristics should define a physical fire model, identifies the data appropriate for assessing the validity of

a physical fire model and provides technical criteria for evaluating them with regard to the accuracy of their

data relevant to life safety.

5.5 This part of ISO 16312 does not address means for combining the effluent component yields to

[7]

estimate the effects on laboratory animals (see ISO 13344 ) or for extrapolating the test results to people

(see ISO 13571).
6 The ideal fire effluent toxicity test method
6.1 Fire stages

6.1.1 The combustion and/or pyrolysis conditions in the combustor section of the apparatus reproduce the

conditions in one or more stages of actual fires, including incipient, growing and fully developed fires.

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ISO 16312-1:2010(E)

6.1.2 Specimens are burned under constant, pre-selected conditions of thermal insult and oxygen

availability (ventilation). The decomposition conditions and decomposition behaviour of the specimen enable

yields to be characterized for specific condition parameters.

6.1.3 For initial and progressive smouldering, the effects of specimen bulk and thermal properties are

considered.

6.1.4 For growth and early fire simulations, including oxidative pyrolysis and well ventilated flaming, the

in-use exposed surface of a material or product is exposed to the appropriate thermal insult.

6.1.5 For simulation of the developed stages of a fire, full burning of the test specimen is required.

6.2 Applicability

This method tests homogeneous materials (both solid and cellular) and commercial products (especially

layered, non-uniform specimens), both melting and non-melting, in relevant form and under simulated fire

scenarios. The nature and quantity of the decomposition products are representative of actual fire scenarios.

6.3 Apparatus independence

The apparatus does not impose any significant influence on the results, i.e. the results reflect the burning

behaviour of the test specimen and not apparatus effects. Flame quenching on surfaces should not affect the

nature of the effluent and the effluent should not be subject to ageing effects. The combustion zone and

effluent plume treatment are designed to ensure that these are achieved.
6.4 Operational efficiency
The test equipment is as simple as possible and capable of safe operation.
6.5 Data generated

6.5.1 The method produces direct measurements of the yields of toxic gases and smoke and/or

measurements of the mass concentration of gases and smoke over time, from which the yields may be

calculated. The gases include those expected to contribute to the toxic potency of fire effluent: CO , CO, HCN,

HCl, HBr, HF, NO, NO , SO , acrolein and formaldehyde.
2 2

NOTE The relative importance of the various gases can depend on the harmful effect being considered.

6.5.2 The method produces a measurement of the mass of the test specimen. Preferably, this is obtained

throughout the test to determine whether the yields of the combustion products are changing as the

combustion proceeds. A determination of the final mass allows for the calculation of average yields over the

duration of the test.
6.5.3 The physical fire model is compatible with the use of bioassay methods.
6.6 Accuracy

Sufficient test data and especially gas yield data from the physical fire model have been validated against full

scale and/or real scale fire scenarios. The fire stages for which agreement is achieved and the degree of

agreement are included in Annex A. The test conditions required to achieve that agreement with the specified

fire stages are given.
6.7 Repeatability and reproducibility

Repeatability and reproducibility of data and limits of accuracy have been established by inter-laboratory trial

and are incorporated as part of the standard method.
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ISO 16312-1:2010(E)
7 Characteristics of fire stages
7.1 The stages of fire are characterized in ISO 19706.

7.2 The environmental conditions that characterize the stages of both a fire and a physical fire model are

⎯ ambient temperature;
⎯ temperature at the combustion site (for non-radiation-controlled burning);
⎯ heat flux to the fuel surface (for radiation-controlled burning);
⎯ surface temperature of the test specimen;
⎯ mass loss rate;
⎯ oxygen concentration at the fuel surface and around the flame;

⎯ availability of fresh oxygen to replenish that depleted by combustion (ventilation rate and mixing).

7.2.1 The last three of these parameters are captured in the fuel/air equivalence ratio.

7.2.2 Typical values of these parameters for the various fire stages are presented in Table 1 of ISO 19706.

7.3 The outcomes of the combustion process also form a basis for characterization of the fire stage:

⎯ yields of a (toxicologically important) subset of the hundreds of combustion products;

⎯ carbon monoxide to carbon dioxide ratio ([CO]/[CO ]);

⎯ ratios of “telltale” second-order products of incomplete combustion, such as an aldehyde to carbon

dioxide.
8 Characterization of physical fire models
8.1 Thermal environment in the test specimen
8.1.1 General

The three-dimensional temperature profile around a product undergoing combustion determines both the

burning rate and the yields of the combustion products. The nature of this profile varies with the fire type and

the time at which one is observing the burning. (See Annex A.)
8.1.2 Smouldering
This type of combustion, occurring only in porous materials, is characterized by

a) the direction in which the combustion front moves relative to the direction from which the air is arriving,

and
b) a peak fuel temperature.
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ISO 16312-1:2010(E)
8.1.3 Pyrolysis

Radiative pyrolysis is characterized by a radiant flux to the surface (kW/m ), a surface temperature, and the

thermal inertia of the test specimen. Conductive and convective heating are characterized by a surface

temperature and the thermal inertia of the test specimen.
8.1.4 Flaming

Flaming combustion is characterized by any imposed radiant flux from the flames and from the apparatus

surfaces, the fuel surface temperature and the thermal inertia of the test specimen.

8.2 Oxygen availability
8.2.1 General

The oxygen percentage (generally expressed as a mole, mass, or volume fraction or percent) determines the

local and instantaneous burning rate of the product or material. There are multiple ways to characterize the

availability of oxygen for burning.
8.2.2 Fuel/air equivalence ratio

8.2.2.1 Global equivalence ratios are most often cited (although not always cited as such) for the

following reasons.

⎯ The equivalence ratio is not usually uniform over the total combusting surface.

⎯ The local values a
...

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