ISO/TR 11696-2:1999
(Main)Uses of reaction to fire test results — Part 2: Fire hazard assessment of construction products
Uses of reaction to fire test results — Part 2: Fire hazard assessment of construction products
This part of ISO/TR 11696 provides guidance on the principles and use of fire test data and other relevant information concerning construction products and their end-use environment, so that potential fire hazards and/or risks may be assessed. It suggests procedures for expressing results and how to interpret the data to aid the fire hazard assessment process. The guidance given is aimed at materials manufacturers and convertors, designers, wholesalers and retailers, specifiers and regulating bodies, and consumer representatives.
Utilisation des résultats des essais de réaction au feu — Partie 2: Évaluation du risque-feu des produits de construction
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 11696-2
First edition
1999-12-15
Uses of reaction to fire test results —
Part 2:
Fire hazard assessment of construction
products
Utilisation des résultats des essais de réaction au feu —
Partie 2: Évaluation du risque-feu des produits de construction
Reference number
ISO/TR 11696-2:1999(E)
©
ISO 1999
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ISO/TR 11696-2:1999(E)
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ISO/TR 11696-2:1999(E)
Contents Page
Foreword.iv
Introduction.v
1 Scope .1
2 References.1
3 Terms and definitions .2
4 Fire characteristics.3
5 Fire hazard assessment .4
6 The decision tree .6
6.1 Step 1 — Definition of fire scenario (probabilistic).6
6.2 Step 2 — Ignition hazard (deterministic).6
6.3 Step 3 — Fire growth hazard (deterministic) .7
6.4 Step 4 — Smoke (deterministic).7
6.5 Step 5 — Rate of hazard development (probabilistic) .7
7 Factors affecting fire growth and the extent of their importance.10
7.1 Step 1 — Definition of fire scenario.10
7.2 Step 2 — Ignition.10
7.3 Step 3 — Fire development.13
7.4 Step 4 — Smoke.17
7.5 Step 5 — Rate of hazard development .18
Annex A An example of a quantitative assessment of fire test data.20
Annex B Guidelines to classification data from ISO fire tests.23
Annex C An example of a calculation of visibility within a building on fire .27
Bibliography.29
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ISO/TR 11696-2:1999(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 3.
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.
In exceptional circumstances, when a technical committee has collected data of a different kind from that which is
normally published as an International Standard ("state of the art", for example), it may decide by a simple majority
vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature
and does not have to be reviewed until the data it provides are considered to be no longer valid or useful.
Attention is drawn to the possibility that some of the elements of this part of ISO/TR 11696 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO/TR 11696-2 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 1, Fire initiation
and growth.
ISO/TR 11696 consists of the following parts, under the general title Uses of reaction to fire test results:
� Part 1: Application of test results to predict fire performance of internal linings and other building products
� Part 2: Fire hazard assessment of construction products
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ISO/TR 11696-2:1999(E)
Introduction
This part of ISO/TR 11696 provides guidance on how to assess reaction to fire test results for construction products
from tests developed in ISO/TC92/SC1. It provides a basis for reaching an informed judgement when balancing out
any conflicting elements which may arise in a risk assessment exercise, where, of necessity, account must always
be taken of many practical considerations.
The document has been designed to provide guidelines to be followed when assessing reaction-to-fire test results
within the context of the overall hazard presented by a defined fire scenario. When using this guide, account should
be taken of any statutory or control requirements (for example building regulations), information obtained from fire
tests such as those developed by other organizations, published literature on non-standard tests and analytical and
biological studies of fire atmospheres.
By establishing a toolkit of new fire tests, ISO/TC92/SC1 has provided a greatly improved facility for measuring the
fire behaviour of materials and products more meaningfully than hitherto. The new test methods also provide data
which can also be used in extended calculations and computer models to provide predictions of fire performance in
a wide range of environments. The use of the test results in extended calculations and models has been explained
in detail in ISO/TR 11696-1. At present, only a relatively small number of people and organizations are able to
make use of the fire test data in this way, although a much larger number of organizations are able to conduct the
tests and obtain the measurements. ISO/TR 11696-2 is intended to provide advice and guidance on the use of ISO
toolkit test data by people and organizations who do not have facilities for extended calculations or computer
models. Large numbers of test systems have been constructed and installed in many commercial fire test
laboratories, the laboratories of materials manufacturers, universities and research institutions. A large number of
users of the test apparatus currently require guidance in the use and interpretation of the results obtained.
Assessment of test results needs guidance, which provides a simplified method. With such guidance, results from
the tests can be used by those who may not have knowledge of the mathematical modelling and the more complex
fire science calculations. ISO/TR 11696-2 has been designed to encourage widespread acceptance of the tests by
providing simplified guidance on the use of the results.
This guide enables assessment to be made of the likely fire hazards to occupants of existing buildings and
transport as well as the effect that alterations to these structures may have on possible hazards. Experience with
the specific procedure of this guide is limited to a few applications at present and more validation of the decision
tree method is required. The concept of controlling the fire performance of construction products by assessing the
contribution of products in reaction to fire tests is used widely by regulators.
It is recognized that the limitation and control of fire hazards will enable people to be confident in the safety of
buildings and transport since fires would then be unlikely to occur and if one did, people would be able to escape.
Fire testing is, however, only one of the techniques by which fire hazards and risks are limited and controlled. Other
techniques include the application of codes of practice, laws controlling flammable materials and their misuse,
inspection and education services provided by fire brigades, as well as fire detectors, sprinklers and other
firefighting equipment.
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TECHNICAL REPORT ISO/TR 11696-2:1999(E)
Uses of reaction to fire test results —
Part 2:
Fire hazard assessment of construction products
1 Scope
This part of ISO/TR 11696 provides guidance on the principles and use of fire test data and other relevant
information concerning construction products and their end-use environment, so that potential fire hazards and/or
risks may be assessed. It suggests procedures for expressing results and how to interpret the data to aid the fire
hazard assessment process. The guidance given is aimed at materials manufacturers and convertors, designers,
wholesalers and retailers, specifiers and regulating bodies, and consumer representatives.
2 References
ISO/IEC Guide 52, Glossary of fire terms and definitions.
ISO 1182, Reaction to fire tests for building products — Non-combustibility test.
ISO 1210, Plastics — Determination of the burning behaviour of horizontal and vertical specimens in contact with a
small-flame ignition source.
ISO 1716, Reaction to fire tests for building products — Determination of the gross calorific value.
ISO 5657, Reaction to fire tests — Ignitability of building products using a radiant heat source.
ISO/TR 5658-1, Reaction to fire tests — Spread of flame — Part 1: Guidance on flame spread.
ISO 5658-2, Reaction to fire tests — Spread of flame — Part 2: Lateral spread on building products in vertical
configuration.
ISO 5658-4, Reaction to fire tests — Spread of flame — Part 4: Intermediate-scale test of vertical spread of flame
with vertically oriented specimen.
ISO 5659-2, Plastics — Smoke generation — Part 2: Determination of optical density by a single-chamber test.
ISO 5660-1, Reaction to fire tests — Heat release, smoke production and mass loss rate — Part 1: Heat release
rate (Cone calorimeter method).
ISO 5660-2, Reaction to fire tests — Heat release, smoke production and mass loss rate from building products —
Part 2: Smoke production rate (dynamic measurement).
ISO 6925, Textile floor coverings — Burning behaviour — Tablet test at ambient temperature.
ISO 6941, Textile fabrics — Burning behaviour — Measurement of flame spread properties of vertically oriented
specimens.
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ISO/TR 9122-6, Toxicity testing of fire effluents — Part 6: Guidance for regulators and specifiers on the
assessment of toxic hazards in fires in buildings and transport.
ISO 9239-1, Reaction to fire tests for floor coverings — Part 1: Determination of the burning behaviour using a
radiant heat source.
ISO 9239-2, Reaction to fire tests — Horizontal surface spread of flame on floor coverings — Part 2: Flame spread
at higher heat flux levels.
ISO 9705, Fire tests — Full-scale room test for surface products.
ISO 10093, Plastics — Fire tests — Standard ignition sources.
ISO 10351, Plastics — Determination of the combustibility of specimens using a 125 mm flame source.
ISO/TR 11696-1, Uses of reaction to fire test results — Part 1: Application of results to predict fire performance of
internal linings and other building products.
ISO/TR 11925-1, Reaction to fire tests — Ignitability of building products subjected to direct impingement of
flame — Part 1: Guidance on ignitability.
ISO 11925-2, Reaction to fire tests — Ignitability of building products subjected to direct impingement of flame —
Part 2: Single-flame source test.
ISO 11925-3, Reaction to fire tests — Ignitability of building products subjected to direct impingement of flame —
Part 3: Multi-source test.
ISO 12992, Plastics — Vertical flame spread determination for film and sheet.
ISO/TR 13387 (all parts), Fire safety engineering.
ISO 13784-1, Reaction to fire tests — Scale tests for industrial sandwich panels — Part 1: Intermediate scale test.
ISO 13784-2, Reaction to fire tests — Scale tests for industrial sandwich panels — Part 2: Large-scale test.
ISO 13785-1, Reaction to fire tests on façades — Part 1: Intermediate scale test.
ISO 13785-2, Reaction to fire tests on façades — Part 2: Large scale tests.
ISO/TR 14696, Reaction to fire tests — Determination of fire parameters of materials, products and assemblies
using an intermediate-scale heat release calorimeter (ICAL).
IEC 61034-1, Measurement of smoke density of cables burning under defined conditions — Part 1: Test apparatus.
IEC 61034-2, Measurement of smoke density of cables burning under defined conditions — Part 2: Test procedure
and requirements.
ASTM E1321, Standard Test Method for Determining Material Ignition and Flame Spread Properties.
3 Terms and definitions
For the purposes of this part of ISO/TR 11696, the terms and definitions given in ISO/IEC Guide 52 and the
following apply.
3.1
fire hazard
the potential degree of personal injury or damage to property by a fire
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3.2
fire risk
the expected loss from a fire is defined in terms of probability as the product of:
� frequency of occurrence of an undesired event to be expected in a given technical operation or state; and,
� consequence or extent of damage to be expected on the occurrence of the event
3.3
smoke
visible part of fire effluent
3.4
thermal inertia
a parameter usually represented as kDc where:
k is thermal conductivity (W/mK);
3
D is density (kg/m );
c is specific heat (J/g·�C).
NOTE This is an important parameter which governs the rate of surface temperature rise of a product when it is exposed to
a heat flux.
4 Fire characteristics
By its nature, fire is a complex phenomenon, with its growth and ultimate severity depending upon a number of
interrelated factors. For the purpose of this part of ISO/TR 11696, uncontrolled development of most fires can be
divided into the following stages.
a) Initiation: The process of heating a material to ignition and thereby establishing a fire, during which the
continued release of flammable vapours leads to sustained combustion;
b) Growth: The spread or propagation of the fire which continues until there are no further supplies of
immediately accessible fuel (combustibles) or air to become involved. This stage may involve the ignition of
adjacent combustible materials;
c) Flashover: The sudden transition from a localized fire to combustion of all exposed fuel surfaces within an
enclosure;
d) Fully developed fire: The stage at which the fire may be said to be "fully developed" and all combustible
materials are burning at a rate controlled by the supply of air to burning surfaces;
e) Decay: The final stage during which the fire is burning itself out.
Heat produced by a typical uncontrolled fire in an enclosure changes with time (see Figure 1) and is affected by the
design of the compartment and the ventilation conditions. Figure 1 also shows the four stages of development of
the fire and the flashover point. The duration and severity of the fire at each stage varies markedly with the rate of
air supply to the combustion zone. The degree of risk to life and property is, in turn, largely controlled by the stage
to which the fire has progressed. The contribution of different products, components and elements of construction
to those risks may also change considerably from one stage to another.
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Initiation Fire growth Fully developed Fire decay
NOTE Not all fires go to flashover.
Figure 1 — Diagram showing the different phases in the development
of a fire within an enclosed space
5 Fire hazard assessment
Realistic assessment of the fire performance of a product can only be obtained by considering a representative
sample in the form and orientation in which it is actually used; an isolated assessment of this kind can only indicate
the response of the product to the combustion environment selected. It must be emphasized, however, that no fire
test can in normal circumstances measure fire hazard, nor can it be assumed that satisfactory results on a single
standard fire test will guarantee a certain level of safety. Results from a variety of fire tests will provide information
to assist in the determination and subsequent control of fire hazard assessment. A schematic representation of
hazard assessment is given in Figure 2.
If a fire chain as depicted in Figures 1 and 2 can develop, a detailed appraisal of the proposed use of the product
should be carried out. This process is necessary so that decisions may be taken about the type of action which will
eliminate or reduce the severity of any potential fire hazards. It is recommended that this appraisal process is
performed in a standardized procedure so that all relevant factors are considered.
The standardized procedure recommended is to consider the input data from the ISO toolkit tests as providing the
bottom layer of a decision tree triangle (that is, the database is the roots of the tree) (see Figure 3). Where no
evidence exists from modelling studies for the scenario under consideration, there will be a need to conduct
additional testing (probably on a large scale, and possibly of an ad hoc nature). The middle layer of the decision
tree triangle is therefore a correlation table between the test results and the full-scale behaviour. There will be gaps
in this table initially and so it is recognized that additional validation information (often of an ad hoc nature) will
need to be provided at the revision stages of this part of ISO/TR 11696.
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Figure 2 — Hazard/risk assessment
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Figure 3 — The decision tree triangle showing input of test data
This part of ISO/TR 11696 suggests a 5-step approach to fire hazard assessment based upon a decision tree; the
decisions about the acceptability of the fire safety questions may be made using classification techniques or
mathematical modelling (or combinations of both). The decision process used and the level of acceptable results is
the responsibility of individual regulators, users, etc.
The procedure for fire hazard assessment assumes that fires develop in the manner indicated in clause 4. It is then
possible to consider the stages of a potential fire in different steps. It is particularly important to note that at each
step data from fire tests are considered together with information on the product design and anticipated conditions
of the fire scenario.
6 The decision tree
NOTE The complete 5-step process is illustrated in Figure 4.
6.1 Step 1 — Definition of fire scenario (probabilistic)
Consideration should be given to both the immediate fire site and to the surrounding areas which may
subsequently become involved. Once the scenario has been defined, the probability of its occurrence should be
assessed. It is important to include a diagram of the scenario and the anticipated smoke movement at this step.
6.2 Step 2 — Ignition hazard (deterministic)
Fire statistics are available on ignition sources and the causes of fire in different environments (for example,
domestic and industrial buildings) and they should be consulted. These statistics can be used to assess the relative
probability of specific ignition incidents.
Ignition sources selected for tests should be relevant to those considered to be realistically capable of existing in
the defined scenario.
Factors influencing the decision about whether there is an ignition risk are shown in Figure 5. A reliable decision
can only be made if each factor is carefully considered in terms of potential influences on the ignition hazard (see
clause 7).
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6.3 Step 3 — Fire growth hazard (deterministic)
After ignition, the surroundings affect fire growth to an increasing extent. Factors influencing the decision about
whether the rate of fire growth presents an acceptable hazard or not are shown in Figure 6 (see clause 7).
6.4 Step 4 — Smoke (deterministic)
The rate of smoke development is important in determining the effective obscuration of vision which determines
when escape becomes impossible. It is therefore a contributor to the overall life hazard.
It is widely recognized that the actual smoke evolution at any point in time is dependent not only on the inherent
smoke generating properties of the materials involved, but also on the total amount burning and on decomposition
conditions. Indeed, in many circumstances the latter may be more important. Similarly, the rate of fire spread
determines how much new material becomes involved in a fire and hence has a relationship to the smoke and toxic
gas development.
Data from as many relevant smoke tests as possible should be considered at step 4. These tests may include
material as well as product tests. They should cover smoke opacity and smoke toxicity and rate of generation of
smoke. It is important also to collect data on rate of mass loss for consideration at step 4 (see Figure 7 and
clause 7).
6.5 Step 5 — Rate of hazard development (probabilistic)
Fire generates a hazardous environment when it is developing. It is vital to be able to assess the point at which the
hazard becomes unacceptable. Factors influencing this decision are shown in Figure 8 (see clause 7). When the
available data indicate that the supplier or user should "redesign", alternative approaches should be taken to
improve the fire performance of the product, for example use improved formulation or incorporate protective layers
to inhibit fire growth.
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Figure 4 — Decision tree for fire hazard assessment
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Figure 5 — Fire hazard assessment: Step 2
Figure 6 — Fire hazard assessment: Step 3
Figure 7 — Fire hazard assessment: Step 4
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Figure 8 — Fire hazard assessment: Step 5
7 Factors affecting fire growth and the extent of their importance
7.1 Step 1 — Definition of fire scenario
7.1.1 Product description
The product for which hazard assessment is required should be described as fully as possible. This description
should include details about its composition and assembly (such as type of substrate, orientation, fixing and
presence of air gaps). Particular consideration should be given to description of end-use fixing in the fire scenario
to be assessed.
7.1.2 Geometry
The geometry of the fire scenario should be described as closely as possible. This description, which should be
supported by drawings, should include the dimensions of the fire enclosure and any relevant features which may
affect air and smoke flow. The possible sites of ignition sources should in particular be identified.
7.1.3 Ventilation
The ventilation conditions in the fire scenario should be detailed. This description should include positions of the
doors and windows as well as ducts or other air-conditioning systems.
7.1.4 Active fire protection systems
The presence of smoke detectors and sprinklers should be described. For specific guidance on active fire
protection other documents should be consulted (see ISO/TR 13387).
7.2 Step 2 — Ignition
7.2.1 Product design
7.2.1.1 Area exposed
A reduction in the area exposed reduces the probability of contact with the ignition source.
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The size of the exposed area will increase or decrease the ease of ignition depending on the thermal inertia of the
surface.
7.2.1.2 Orientation
A vertical orientation allows hot volatiles to diffuse upwards, diluting with air to form a range of concentrations.
A horizontal (facing up) orientation ensures that volatiles will mix with air but at low concentrations.
A horizontal (facing down) orientation will restrict volatiles mixing with air but will increase their concentration.
7.2.1.3 Interaction of angled surfaces
Angled surfaces conserve heat, re-radiate and exaggerate the effect of physical properties such as thermal inertia.
7.2.1.4 Form of surface
A rough surface increases the area exposed to the source and thus increases the effect of thermal inertia.
7.2.1.5 Thickness of product
Thin products increase the rate of temperature rise of a surface and speed of ignition. The nature of the substrate
can have a significant influence on the thermal behaviour.
7.2.1.6 Composition of material
The chemical properties of a material will determine the rate of emission of volatiles and the ignition temperature of
volatiles.
The nature of a plastic material (whether thermoplastic or thermoset) will determine whether melting or slumping
behaviour may be expected.
Some materials (for example plastics) may contain fire retardants, fillers or reinforcing fibres; if possible their
chemical composition and concentrations should be recorded.
7.2.1.7 Physical nature of material
The thermal inertia of the surface and of the substrate should be considered together with the effectiveness of the
adhesion to the substrate.
It is important to note that a material with a low thermal inertia value will retain heat in the surface layers and the
temperature will more rapidly reach that at which decomposition begins.
7.2.2 Scenario
7.2.2.1 Enclosures
The size of the enclosure is not an important consideration at the ignition stage.
7.2.2.2 Ignition source
The ignition source is of fundamental importance when defining the scenario and the following characteristics of
ignition sources should be considered:
a) intensity of the ignition source. The thermal transfer to the product may be by radiation, conduction and
convection;
b) area of contact of the ignition source, or the distance between ignition source and exposed surfaces;
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c) orientation of the product relative to the ignition source;
d) ventilation conditions around the ignit
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