ISO 10840:2003
(Main)Plastics — Guidance for the use of standard fire tests
Plastics — Guidance for the use of standard fire tests
ISO 10840:2003 covers the following aspects of fire testing: selection of appropriate test(s); listing of reaction-to-fire characteristics which the test(s) can measure; assessment of the test(s) for their suitability for material characterization, quality control, pre-selection and/or end-product testing; problems that can arise when plastics specimens are tested in standard fire tests. Particular attention is given to the provision of guidance for inexperienced users who may need to assess the fire performance of materials or products made of, or incorporating, plastics. This International Standard also provides answers to frequently asked questions concerning standard fire tests; these cover factors such as cost, test duration, complexity, required operator skills, quality of the data produced, relevance to fire hazard assessment as well as test repeatability and reproducibility. The main focus in this International Standard is on reaction-to-fire testing. Fire-resistance testing has also been considered, however, in order to take account of the widespread use of advanced polymer composites and related materials with superior thermo-mechanical stability which may be used in applications where there is a demand for some degree of fire resistance. Further development of such plastics composites and related products will predictably increase the demand for fire-resistance testing. The scope of this International Standard does not include the development or design of fire tests for plastics.
Plastiques — Lignes directrices pour l'utilisation d'essais au feu normalisés
Polimerni materiali – Napotki za uporabo standardnih preskusov z ognjem
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 10840
First edition
2003-03-01
Plastics — Guidance for the use of
standard fire tests
Plastiques — Lignes directrices pour l'utilisation d'essais au feu
normalisés
Reference number
ISO 10840:2003(E)
©
ISO 2003
---------------------- Page: 1 ----------------------
ISO 10840:2003(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2003
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2003 — All rights reserved
---------------------- Page: 2 ----------------------
ISO 10840:2003(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Fire scenarios. 2
5 Categories of fire test . 4
6 Important considerations in the fire testing of plastics materials and products. 5
7 Problems that may occur with plastics in standard fire tests. 11
Bibliography . 13
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ISO 10840:2003(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 10840 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning
behaviour.
This first edition of ISO 10840 cancels and replaces ISO/TR 10840:1993, which has been technically revised.
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ISO 10840:2003(E)
Introduction
Many of the current reaction-to-fire tests were developed, prior to the widespread use of synthetic polymers, to
assess products incorporating materials such as wood (in the building industry), paper (in electrical wires and
cables), and naturally occurring fibres such as cotton, wool and horsehair (in many textile, furniture and
electrical applications). The “reaction-to-fire” characteristics of these “traditional” or “older-generation”
materials are often very different from those of synthetic materials, especially thermoplastics.
ISO/TC 61/SC 4 has, for a number of years, recognized the need for guidance for users of fire-test standards
commonly applied to materials and products made of, or incorporating, plastics. During 1997, it decided to
develop a guidance document in the form of an International Standard using ISO/TR 10840, and particularly
its Annex A, as the basis.
Annex A of ISO/TR 10840:1993 listed a series of potential problems associated with the reaction-to-fire testing
of plastics materials and products. However, it provided users of the test methods with no practical assistance
on how to cope with the difficulties listed.
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INTERNATIONAL STANDARD ISO 10840:2003(E)
Plastics — Guidance for the use of standard fire tests
1 Scope
This International Standard covers the following aspects of fire testing:
selection of appropriate test(s);
listing of reaction-to-fire characteristics which the test(s) can measure;
assessment of the test(s) for their suitability for material characterization, quality control, pre-selection
and/or end-product testing;
problems that can arise when plastics specimens are tested in standard fire tests.
Particular attention is given to the provision of guidance for inexperienced users who may need to assess the
fire performance of materials or products made of, or incorporating, plastics. This International Standard also
provides answers to frequently asked questions concerning standard fire tests; these cover factors such as
cost, test duration, complexity, required operator skills, quality of the data produced, relevance to fire hazard
assessment as well as test repeatability and reproducibility. Preparation of this International Standard has
involved a review and assessment of the most frequently used fire tests applied to the materials and products
within the scope of ISO/TC 61/SC 4.
The main focus in this International Standard is on reaction-to-fire testing. Fire-resistance testing has also
been considered, however, in order to take account of the widespread use of advanced polymer composites
and related materials with superior thermo-mechanical stability which may be used in applications where there
is a demand for some degree of fire resistance. Further development of such plastics composites and related
products will predictably increase the demand for fire-resistance testing.
The scope of this International Standard does not include the development or design of fire tests for plastics.
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 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.
3.1
test specimen
test piece that may be cut from a sample of a product, or prepared by moulding or otherwise, as specified by
the test procedure, or a representative sample of the product itself
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ISO 10840:2003(E)
3.2
sample
representative part of a manufactured product or piece of material or semi-finished product
3.3
plastics end-product test
test made on a complete product, piece, part, component or sub-assembly
3.4
plastics pre-selection test
test made on a standardized shape, for example a rectangular bar prepared using standard moulding
procedures
4 Fire scenarios
4.1 General
A number of fire parameters influence the development of a fire and, moreover, the fire parameters measured
during the pre-flashover and the post-flashover stages differ greatly.
There are four main stages in the development of a fire within an enclosed space. These are assessed using
measurements of temperature and time as shown in Figure 1.
4.2 Initiation and early growth
This stage includes the exposure of a product to a heat source, ignition and early development of a fire. Two
types of combustion may exist at this stage, smouldering and flaming. Smouldering is a slow, flameless
combustion producing very little heat, but having the potential to fill an enclosed space with smoke and toxic
gases.
After ignition, the development of a flaming fire will depend on the following factors:
fire growth on the item first ignited;
fire spread to other items;
the effect of intervention (portable extinguishers, sprinklers, fire brigades);
the ventilation conditions.
4.3 Development of fire
As a fire develops, a hot smoke and gas layer usually builds up below the ceiling.
The radiant heat transfer to combustible items accelerates the thermal decomposition of material below the
smoke layer, and the rate of fire spread increases.
Flashover is the sudden transition from a localized fire to the ignition of the gas layer and subsequently of all
exposed flammable surfaces, and will lead to a fully developed fire. Flashover is uncommon in large enclosed
spaces, as the temperature conditions required are not often reached.
Flashover usually occurs at temperatures around 600 °C; thereafter, the rate of heat release increases rapidly
to reach a maximum value.
4.4 Fully developed fire
A fire is regarded as fully developed when all fuel within the enclosed space is burning. This stage usually
follows flashover, but some fires may become fully developed without passing through the flashover phase.
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ISO 10840:2003(E)
Key
1 time to ignition
2
2 T > 100 °C, I > 25 kW/m close to ignited item
3 developing fire
4 flashover
5 fully developed fire
Figure 1 — Typical course of a fire going to flashover in an enclosed space
4.5 Decay
The decay stage of a fire is reached when all the combustible material or available air has been consumed, or
when the fire is suppressed. In the pre-flashover phase, reaction-to-fire characteristics of products are
important, while in the post-flashover phase resistance-to-fire parameters of complete assemblies apply.
Fire building regulations make a distinction between these two conditions. Table 1 summarizes the important
fire parameters associated with reaction to fire and resistance to fire.
Table 1 — Phases of a fire
Phase Stage Parameters
Pre-flashover Initiation Ignitability
Developing fire Fire growth (ignitability, flame spread, and heat,
smoke and toxic-effluent release)
Post-flashover Developed fire Resistance to fire (load-bearing capability,
integrity, insulating capability)
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ISO 10840:2003(E)
5 Categories of fire test
5.1 Material-characterization tests
5.1.1 Tests carried out on behalf of customers who will undertake no further reaction-to-fire testing
on the material, or on products manufactured from the material
This type of testing imposes an obligation on the material supplier to assess those reaction-to-fire
characteristics of the material likely to be of relevance to the application of the customer’s product, or
foreseeable misuse of the product as may be imposed by product stewardship aspects of responsible-care
programmes, or product-liability litigation, or both. The objective should be to provide answers to questions
such as:
a) Do the properties of thermal-decomposition products (smoke density, toxicity or corrosivity) pose a
foreseeable problem?
b) Is the thermo-mechanical response of the material (e.g. melting or retreating from the heat source) likely
to constitute a hazard or an advantage in the customer’s product application, or in foreseeable misuse
scenarios?
5.1.2 Tests carried out on behalf of a customer who seeks compliance with reaction-to-fire test(s) on
the finished product
In this case, the test method(s) used by the material manufacturer should provide an indication of the likely
influence on the test result of characteristics such as melting, dripping and retreat from the heat source.
5.2 Quality-control tests
In order to select a quality-control test, it is important to
a) decide which characteristics should be checked by the test;
b) select or develop the appropriate test method;
c) specify the required performance criteria;
d) compare test results to ensure that the parameter measured by the quality-control test is correlatable with
the key performance parameter being investigated.
It is necessary to specify:
a) the characteristics which have to be checked by the test;
b) the appropriate test procedure;
c) the required pass (acceptance) and fail (rejection) criteria;
and then to compare the test results with the specified criteria (acceptance level).
Repeatability is of crucial importance in tests selected for the purpose of quality control; in this context, the
relevance of the test to any given application of the material is of secondary importance.
5.3 Pre-selection tests
Data developed using pre-selection tests requires careful consideration to ensure their relevance in relation to
the intended application and to avoid misuse and erroneous interpretation.
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ISO 10840:2003(E)
The actual fire performance of a product is affected by its surroundings, design variables such as shape and
size, fabrication techniques, heat-transfer effects, the type of potential ignition source and the length of
exposure to it.
The advantages of pre-selection testing are as follows:
a) To a first approximation, a material which reacts more favourably than another when tested as a standard
test specimen will usually also react more favourably when tested as a finished product or component.
This will be valid provided that no overriding, interactive, product-specific effects are present.
b) Data concerning relevant combustion characteristics can aid in the selection of materials, components
and sub-assemblies during the design stage.
c) The precision of pre-selection tests is usually higher, and their sensitivity may be superior when
compared with end-product tests.
d) Pre-selection tests may be used in a decision-making process directed to minimize the fire hazard. Where
applicable for the purpose of fire-hazard assessment, they may lead to a reduction in the number of end-
product tests with a consequent reduction in the total test effort.
e) When fire-hazard requirements need to be upgraded quickly, it may be possible to do this by upgrading
the requirements of a pre-selection test before modifying the end-product test.
f) The grading and classification obtained from the pre-selection test results may be used to specify a basic
minimum performance for materials used in product specifications.
It should be noted that, when pre-selection testing is used to replace some of the end-product testing, it is
necessary to fix an increased margin of safety in an attempt to ensure satisfactory performance of the end
product. Following a pre-selection procedure, it may be necessary to carry out a value analysis on the end
product, in order not to over-specify materials where a more economical material is suitable. In this case, an
end-product test may be needed.
5.4 End-product tests
These tests should reflect the end-use scenario as far as is possible. Important factors to consider include the
relevance of configuration, orientation and ventilation, and the nature of the ignition source.
Reaction-to-fire testing for fire-safety and for fire-hazard assessment of products should be programmed as
follows:
a) specify the fire hazard to be assessed (e.g. vision impairment by smoke);
b) define the relevant product-application (or misuse) scenario and specify the required safety criterion;
c) select the appropriate test method and specify the pass/fail criterion;
d) conduct the tests and analyse the data;
e) select acceptable or reject unacceptable candidate materials or products.
6 Important considerations in the fire testing of plastics materials and products
6.1 Possible influence of the chemical or physical nature of the specimen on the execution
of the tests
Various chemical and/or physical aspects of the material may affect the performance of the specimen at the
high temperatures encountered in standard fire-testing procedures. These may be categorized under various
headings, depending on whether the observed phenomena are associated with the specimen itself and/or the
test apparatus and/or the execution of the test procedure and/or the interpretation of the test results.
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ISO 10840:2003(E)
6.2 Thermal-decomposition products
6.2.1 General
When an ignition source is applied to any plastics test specimen made from pure, compounded or laminated
material, thermal-decomposition products will be generated. The nature of the decomposition products is not
determined exclusively by the chemical composition of the test specimen. Other determinant factors are:
a) the energy output of the ignition source;
b) the nature of the ignition source:
flaming or non-flaming,
impingement or non-impingement of the source on the specimen;
c) the nature of the test apparatus:
high or low ventilation,
high or low thermal inertia (i.e. significance of heat-sink effects).
6.2.2 The nature of the thermal-decomposition products
These may consist of:
a) toxic or corrosive decomposition products;
b) smoke and soot;
c) charred and intumesced layers.
6.3 Practical problems posed by specimen decomposition effects
The following types of effect may occur:
a) evaporation or sublimation of additives;
b) out-gassing or intumescence;
c) char-layer formation;
d) delamination;
e) spalling;
f) punking.
6.4 Health, safety and environmental considerations relevant to fire-test operation and
post-test clean-up procedures
The following factors should be taken into account:
a) operator safety, especially from fast fire-growth, as in flashovers, and from exposure to smoke and toxic
effluents, particularly in large-scale tests such as ISO 9705;
b) effects of heat on structures in large-scale test procedures (dangers of structural collapse);
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ISO 10840:2003(E)
c) the need for personal protective equipment;
d) the local environmental impact on the air, the water and the soil;
e) compliance with local regulations;
f) avoidance of local nuisance as required by responsible-care commitment;
g) identification and control of effluents;
h) equipment corrosion;
i) smoke or gas explosion hazards.
6.5 Considerations related to specimen geometry
It is important to define selection criteria for specimens removed from a sample such as a TV set.
Other influential factors may be:
Specimen thickness: Heat and smoke release depend on thickness. Thicker specimens may release much
more heat and smoke than thin specimens. Thin specimens may ignite more easily than thick specimens
because of thermal-inertia effects.
Specimen size.
Specimen form, as determined by the specimen's shape and aspect ratio.
Edge effects: Sharp edges may ignite more readily than rounded edges.
Orientation and ventilation: Flame spread will depend on the air-to-gas ratio and the flow of gaseous
species in the vicinity of the flame.
Specimen support, including air-gaps: Conductive air-flow between the specimen and its support system
may affect the temperature-rise profile and, consequently, the ignitability and flame-spread behaviour of the
specimen. Limitation of specimen movement by the specimen-support system may also affect the specimen's
response to the ignition source.
6.6 Ignition-source characteristics that influence the test results and the interpretation of
the results
The relevance of ignition sources depends on the selection of fire scenarios in which the product is to be
evaluated for fire hazard. Fundamentally, heat flow from the heat source to the specimen is a major parameter
in such evaluation; it also depends on the relative sizes of the specimen and the ignition source. Thus the test
result may depend on many design features of the test system. The following characteristics of the ignition
source should be taken into account:
a) radiant, conductive and convective properties;
b) flaming or non-flaming;
c) impingement or non-impingement of ignition source on specimen;
d) precision and quantification of measurements;
e) flame stability.
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ISO 10840:2003(E)
6.7 Specimen conditioning and preparation
Specimen conditioning and preparation can be of extreme importance in the fire testing of plastics materials
and products. Such preparation covers selection, sampling and the cutting-out and conditioning of the
specimens. Conditioning is important because variations in the moisture content of specimens will affect the
test results.
It is important to remove moulding flash and other similar adventitious residues from the surfaces and edges
of specimens.
The initial temperature of the specimen may influence its ease of ignition in the test.
Particular attention should be paid to thermo-formed test specimens. The conditions of the thermo-forming
operation, such as injection moulding or extrusion, should be rigorously controlled in order to minimize and, if
possible, eliminate any specimen-to-specimen variations in residual stress, anisotropy, specific gravity and
degree of crystallinity. All of these variables influence the thermo-mechanical properties of the specimen and
consequently its response to the application of heat from the fire-test ignition source.
6.8 Practical advice on contingency operating procedures in the event of specimen
collapse or deformation on exposure to heat from the ignition source
Problems arise in the fire testing of many plastics because of common thermo-mechanical effects such as
specimen slumping and sagging as well as edge effects such as the curling of the thin specimens towards or
away from the ignition source.
Interpreting test results can also be problematical when the operator has to cope with and report variations in
incident flux and/or ignition conditions (impingement/non-impingement of the ignition source) because of
changes in the source-to-specimen distance. Examples of other problem areas are interpretation of observed
non-ignition of the specimen due to its shrink-back from the ignition source and interpreting the effects on the
test result of restraining and supporting devices such as clamps, grids and wires and the masking of specimen
edges.
Such behaviour of the specimen should be reported by the operator in the test report. If the effect is so
extreme as to make it impossible to obtain test data, this should be reported as the reason why the test could
not be carried out.
Thermo-mechanical specimen responses in fire tests on plastics may give rise to localized withdrawal of the
specimen from contact with the ignition source as a result of accelerated stress relaxation within the specimen
under the influence of heat from the ignition source. These effects may manifest themselves in various ways,
depending on the chemical and physical nature of the specimen, its dimensions and its orientation as
determined by the specified test procedure. Examples are:
shrinking;
curling;
sagging;
slumping.
Gravitational effects on the test specimen are determined by its mass, dimensions and orientation. Depending
on these factors, the effect of gravity may result in sagging or slumping of the specimen. These effects may
aggravate or attenuate specimen deformation caused by internal thermo-mechanical stress-relaxation
processes. It may be noted in this connection that problems of slumping of thermoplastics specimens have
been resolved by ISO/TC 61/SC 4 in ISO 5659-2.
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ISO 10840:2003(E)
6.9 Problem-solving approaches to complications caused by melting effects in
thermoplastics
Melting effects can include flaming and non-flaming drip formation, adhesion of the specimen to an ignition
source such as a glow-wire, and melt-pool formation below the test specimen, which may be feeding fuel into,
or away from, the ignition zone.
If the test conditions correspond to foreseeable end-use scenarios, these results should be reported because
they are relevant to hazard and risk assessment. If there is no likely relevance of the test conditions to the end
use, it should be reported that the test could not be carried out as specified, and an alternative test procedure
should be selected.
6.10 Advantages and disadvantages of scale in fire tests
6.10.1 General
Difficulties are often experienced in extrapolating upwards from small-scale to large-scale performance, for
there are always implications to be taken into account in the trade-off between test precision and test
relevance to end-use hazard assessment.
6.10.2 Large-scale, full-scale and real-scale tests
Such tests may offer the only available realistic assessment of the gross effects of thermal deformation and
gravity and the effects of fixtures and joints under end-use conditions in real fires. This raises questions about
the acceptability of small-scale test data on parts of products (or on materials used in products) given that
these effects play a key role in the fire safety of the product in its application scenario.
The large-scale ISO 9705 room/corner test has been used to validate the cone calorimeter for wall and ceiling
linings; it is the reference scenario for European Union classification of building products. Other reference
scenarios include large rooms, ducts, corridors, stair-wells and façades.
The advantage of large-scale tests is their relevance to end-use hazard assessment.
Their disadvantages lie in the operational hazards involved, including safety and environmental aspects, their
cost and their uncertain reproducibility.
6.10.3 Intermediate-scale tests
The major benefits of intermediate-scale tests are associated with their ability to reflect more accurately the
fire conditions of real fires than small-scale tests; for example:
Specimen mounting: Due to the larger test apparatus, specimens can incorporate more readily end-use
fixtures, joints and air-gaps. In addition, thick and/or profiled products may be accommodated. This capability
is valuable for sandwich panels, which can be up to 200 mm thick and may be faced with steel sheet
containing 150-mm-deep profiles. It is also valid for pipes, pipe insulation, cable trays, GRP frames and similar
products.
Ignition sources: The thermal characteristics of ignition sources can be related more closely to those of
design fires. Intermediate-scale tests may use either flame or radiant-heat sources. Gas-burner sources tend
to be more widely used with, typically, heat outputs in the range 30 kW to 300 kW and thermal attack on the
2 2
specimen surface in the range 25 kW/m to 75 kW/m . The energy supplied to test specimens by ignition
sources in small-scale tests is 0,000 3 kW⋅h to 0,3 kW⋅h compared to 1 kW⋅h to 10 kW⋅h in intermediate-scale
tests (and 30 kW⋅h to 150 kW⋅h in large-scale tests).
Test-specimen size and orientation: Intermediate-scale tests allow fire growth to be more realistically
evaluated; hence, the ability to measure flame spread away from the ignition-source impingement zone is a
desirable feature.
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ISO 10840:2003(E)
In addition, since many products (especially thermoplastics) rapidly deform or melt when exposed to ignition
sources, more representative behaviour may be observed with intermediate-scale specimens, which
...
SLOVENSKI STANDARD
SIST ISO 10840:2003
01-julij-2003
Polimerni materiali – Napotki za uporabo standardnih preskusov z ognjem
Plastics -- Guidance for the use of standard fire tests
Plastiques -- Lignes directrices pour l'utilisation d'essais au feu normalisés
Ta slovenski standard je istoveten z: ISO 10840:2003
ICS:
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
83.080.01 Polimerni materiali na Plastics in general
splošno
SIST ISO 10840:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST ISO 10840:2003
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SIST ISO 10840:2003
INTERNATIONAL ISO
STANDARD 10840
First edition
2003-03-01
Plastics — Guidance for the use of
standard fire tests
Plastiques — Lignes directrices pour l'utilisation d'essais au feu
normalisés
Reference number
ISO 10840:2003(E)
©
ISO 2003
---------------------- Page: 3 ----------------------
SIST ISO 10840:2003
ISO 10840:2003(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2003
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2003 — All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 10840:2003
ISO 10840:2003(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Normative references . 1
3 Terms and definitions. 1
4 Fire scenarios. 2
5 Categories of fire test . 4
6 Important considerations in the fire testing of plastics materials and products. 5
7 Problems that may occur with plastics in standard fire tests. 11
Bibliography . 13
© ISO 2003 — All rights reserved iii
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SIST ISO 10840:2003
ISO 10840:2003(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 10840 was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning
behaviour.
This first edition of ISO 10840 cancels and replaces ISO/TR 10840:1993, which has been technically revised.
iv © ISO 2003 — All rights reserved
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SIST ISO 10840:2003
ISO 10840:2003(E)
Introduction
Many of the current reaction-to-fire tests were developed, prior to the widespread use of synthetic polymers, to
assess products incorporating materials such as wood (in the building industry), paper (in electrical wires and
cables), and naturally occurring fibres such as cotton, wool and horsehair (in many textile, furniture and
electrical applications). The “reaction-to-fire” characteristics of these “traditional” or “older-generation”
materials are often very different from those of synthetic materials, especially thermoplastics.
ISO/TC 61/SC 4 has, for a number of years, recognized the need for guidance for users of fire-test standards
commonly applied to materials and products made of, or incorporating, plastics. During 1997, it decided to
develop a guidance document in the form of an International Standard using ISO/TR 10840, and particularly
its Annex A, as the basis.
Annex A of ISO/TR 10840:1993 listed a series of potential problems associated with the reaction-to-fire testing
of plastics materials and products. However, it provided users of the test methods with no practical assistance
on how to cope with the difficulties listed.
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INTERNATIONAL STANDARD ISO 10840:2003(E)
Plastics — Guidance for the use of standard fire tests
1 Scope
This International Standard covers the following aspects of fire testing:
selection of appropriate test(s);
listing of reaction-to-fire characteristics which the test(s) can measure;
assessment of the test(s) for their suitability for material characterization, quality control, pre-selection
and/or end-product testing;
problems that can arise when plastics specimens are tested in standard fire tests.
Particular attention is given to the provision of guidance for inexperienced users who may need to assess the
fire performance of materials or products made of, or incorporating, plastics. This International Standard also
provides answers to frequently asked questions concerning standard fire tests; these cover factors such as
cost, test duration, complexity, required operator skills, quality of the data produced, relevance to fire hazard
assessment as well as test repeatability and reproducibility. Preparation of this International Standard has
involved a review and assessment of the most frequently used fire tests applied to the materials and products
within the scope of ISO/TC 61/SC 4.
The main focus in this International Standard is on reaction-to-fire testing. Fire-resistance testing has also
been considered, however, in order to take account of the widespread use of advanced polymer composites
and related materials with superior thermo-mechanical stability which may be used in applications where there
is a demand for some degree of fire resistance. Further development of such plastics composites and related
products will predictably increase the demand for fire-resistance testing.
The scope of this International Standard does not include the development or design of fire tests for plastics.
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 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.
3.1
test specimen
test piece that may be cut from a sample of a product, or prepared by moulding or otherwise, as specified by
the test procedure, or a representative sample of the product itself
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3.2
sample
representative part of a manufactured product or piece of material or semi-finished product
3.3
plastics end-product test
test made on a complete product, piece, part, component or sub-assembly
3.4
plastics pre-selection test
test made on a standardized shape, for example a rectangular bar prepared using standard moulding
procedures
4 Fire scenarios
4.1 General
A number of fire parameters influence the development of a fire and, moreover, the fire parameters measured
during the pre-flashover and the post-flashover stages differ greatly.
There are four main stages in the development of a fire within an enclosed space. These are assessed using
measurements of temperature and time as shown in Figure 1.
4.2 Initiation and early growth
This stage includes the exposure of a product to a heat source, ignition and early development of a fire. Two
types of combustion may exist at this stage, smouldering and flaming. Smouldering is a slow, flameless
combustion producing very little heat, but having the potential to fill an enclosed space with smoke and toxic
gases.
After ignition, the development of a flaming fire will depend on the following factors:
fire growth on the item first ignited;
fire spread to other items;
the effect of intervention (portable extinguishers, sprinklers, fire brigades);
the ventilation conditions.
4.3 Development of fire
As a fire develops, a hot smoke and gas layer usually builds up below the ceiling.
The radiant heat transfer to combustible items accelerates the thermal decomposition of material below the
smoke layer, and the rate of fire spread increases.
Flashover is the sudden transition from a localized fire to the ignition of the gas layer and subsequently of all
exposed flammable surfaces, and will lead to a fully developed fire. Flashover is uncommon in large enclosed
spaces, as the temperature conditions required are not often reached.
Flashover usually occurs at temperatures around 600 °C; thereafter, the rate of heat release increases rapidly
to reach a maximum value.
4.4 Fully developed fire
A fire is regarded as fully developed when all fuel within the enclosed space is burning. This stage usually
follows flashover, but some fires may become fully developed without passing through the flashover phase.
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Key
1 time to ignition
2
2 T > 100 °C, I > 25 kW/m close to ignited item
3 developing fire
4 flashover
5 fully developed fire
Figure 1 — Typical course of a fire going to flashover in an enclosed space
4.5 Decay
The decay stage of a fire is reached when all the combustible material or available air has been consumed, or
when the fire is suppressed. In the pre-flashover phase, reaction-to-fire characteristics of products are
important, while in the post-flashover phase resistance-to-fire parameters of complete assemblies apply.
Fire building regulations make a distinction between these two conditions. Table 1 summarizes the important
fire parameters associated with reaction to fire and resistance to fire.
Table 1 — Phases of a fire
Phase Stage Parameters
Pre-flashover Initiation Ignitability
Developing fire Fire growth (ignitability, flame spread, and heat,
smoke and toxic-effluent release)
Post-flashover Developed fire Resistance to fire (load-bearing capability,
integrity, insulating capability)
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5 Categories of fire test
5.1 Material-characterization tests
5.1.1 Tests carried out on behalf of customers who will undertake no further reaction-to-fire testing
on the material, or on products manufactured from the material
This type of testing imposes an obligation on the material supplier to assess those reaction-to-fire
characteristics of the material likely to be of relevance to the application of the customer’s product, or
foreseeable misuse of the product as may be imposed by product stewardship aspects of responsible-care
programmes, or product-liability litigation, or both. The objective should be to provide answers to questions
such as:
a) Do the properties of thermal-decomposition products (smoke density, toxicity or corrosivity) pose a
foreseeable problem?
b) Is the thermo-mechanical response of the material (e.g. melting or retreating from the heat source) likely
to constitute a hazard or an advantage in the customer’s product application, or in foreseeable misuse
scenarios?
5.1.2 Tests carried out on behalf of a customer who seeks compliance with reaction-to-fire test(s) on
the finished product
In this case, the test method(s) used by the material manufacturer should provide an indication of the likely
influence on the test result of characteristics such as melting, dripping and retreat from the heat source.
5.2 Quality-control tests
In order to select a quality-control test, it is important to
a) decide which characteristics should be checked by the test;
b) select or develop the appropriate test method;
c) specify the required performance criteria;
d) compare test results to ensure that the parameter measured by the quality-control test is correlatable with
the key performance parameter being investigated.
It is necessary to specify:
a) the characteristics which have to be checked by the test;
b) the appropriate test procedure;
c) the required pass (acceptance) and fail (rejection) criteria;
and then to compare the test results with the specified criteria (acceptance level).
Repeatability is of crucial importance in tests selected for the purpose of quality control; in this context, the
relevance of the test to any given application of the material is of secondary importance.
5.3 Pre-selection tests
Data developed using pre-selection tests requires careful consideration to ensure their relevance in relation to
the intended application and to avoid misuse and erroneous interpretation.
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The actual fire performance of a product is affected by its surroundings, design variables such as shape and
size, fabrication techniques, heat-transfer effects, the type of potential ignition source and the length of
exposure to it.
The advantages of pre-selection testing are as follows:
a) To a first approximation, a material which reacts more favourably than another when tested as a standard
test specimen will usually also react more favourably when tested as a finished product or component.
This will be valid provided that no overriding, interactive, product-specific effects are present.
b) Data concerning relevant combustion characteristics can aid in the selection of materials, components
and sub-assemblies during the design stage.
c) The precision of pre-selection tests is usually higher, and their sensitivity may be superior when
compared with end-product tests.
d) Pre-selection tests may be used in a decision-making process directed to minimize the fire hazard. Where
applicable for the purpose of fire-hazard assessment, they may lead to a reduction in the number of end-
product tests with a consequent reduction in the total test effort.
e) When fire-hazard requirements need to be upgraded quickly, it may be possible to do this by upgrading
the requirements of a pre-selection test before modifying the end-product test.
f) The grading and classification obtained from the pre-selection test results may be used to specify a basic
minimum performance for materials used in product specifications.
It should be noted that, when pre-selection testing is used to replace some of the end-product testing, it is
necessary to fix an increased margin of safety in an attempt to ensure satisfactory performance of the end
product. Following a pre-selection procedure, it may be necessary to carry out a value analysis on the end
product, in order not to over-specify materials where a more economical material is suitable. In this case, an
end-product test may be needed.
5.4 End-product tests
These tests should reflect the end-use scenario as far as is possible. Important factors to consider include the
relevance of configuration, orientation and ventilation, and the nature of the ignition source.
Reaction-to-fire testing for fire-safety and for fire-hazard assessment of products should be programmed as
follows:
a) specify the fire hazard to be assessed (e.g. vision impairment by smoke);
b) define the relevant product-application (or misuse) scenario and specify the required safety criterion;
c) select the appropriate test method and specify the pass/fail criterion;
d) conduct the tests and analyse the data;
e) select acceptable or reject unacceptable candidate materials or products.
6 Important considerations in the fire testing of plastics materials and products
6.1 Possible influence of the chemical or physical nature of the specimen on the execution
of the tests
Various chemical and/or physical aspects of the material may affect the performance of the specimen at the
high temperatures encountered in standard fire-testing procedures. These may be categorized under various
headings, depending on whether the observed phenomena are associated with the specimen itself and/or the
test apparatus and/or the execution of the test procedure and/or the interpretation of the test results.
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6.2 Thermal-decomposition products
6.2.1 General
When an ignition source is applied to any plastics test specimen made from pure, compounded or laminated
material, thermal-decomposition products will be generated. The nature of the decomposition products is not
determined exclusively by the chemical composition of the test specimen. Other determinant factors are:
a) the energy output of the ignition source;
b) the nature of the ignition source:
flaming or non-flaming,
impingement or non-impingement of the source on the specimen;
c) the nature of the test apparatus:
high or low ventilation,
high or low thermal inertia (i.e. significance of heat-sink effects).
6.2.2 The nature of the thermal-decomposition products
These may consist of:
a) toxic or corrosive decomposition products;
b) smoke and soot;
c) charred and intumesced layers.
6.3 Practical problems posed by specimen decomposition effects
The following types of effect may occur:
a) evaporation or sublimation of additives;
b) out-gassing or intumescence;
c) char-layer formation;
d) delamination;
e) spalling;
f) punking.
6.4 Health, safety and environmental considerations relevant to fire-test operation and
post-test clean-up procedures
The following factors should be taken into account:
a) operator safety, especially from fast fire-growth, as in flashovers, and from exposure to smoke and toxic
effluents, particularly in large-scale tests such as ISO 9705;
b) effects of heat on structures in large-scale test procedures (dangers of structural collapse);
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c) the need for personal protective equipment;
d) the local environmental impact on the air, the water and the soil;
e) compliance with local regulations;
f) avoidance of local nuisance as required by responsible-care commitment;
g) identification and control of effluents;
h) equipment corrosion;
i) smoke or gas explosion hazards.
6.5 Considerations related to specimen geometry
It is important to define selection criteria for specimens removed from a sample such as a TV set.
Other influential factors may be:
Specimen thickness: Heat and smoke release depend on thickness. Thicker specimens may release much
more heat and smoke than thin specimens. Thin specimens may ignite more easily than thick specimens
because of thermal-inertia effects.
Specimen size.
Specimen form, as determined by the specimen's shape and aspect ratio.
Edge effects: Sharp edges may ignite more readily than rounded edges.
Orientation and ventilation: Flame spread will depend on the air-to-gas ratio and the flow of gaseous
species in the vicinity of the flame.
Specimen support, including air-gaps: Conductive air-flow between the specimen and its support system
may affect the temperature-rise profile and, consequently, the ignitability and flame-spread behaviour of the
specimen. Limitation of specimen movement by the specimen-support system may also affect the specimen's
response to the ignition source.
6.6 Ignition-source characteristics that influence the test results and the interpretation of
the results
The relevance of ignition sources depends on the selection of fire scenarios in which the product is to be
evaluated for fire hazard. Fundamentally, heat flow from the heat source to the specimen is a major parameter
in such evaluation; it also depends on the relative sizes of the specimen and the ignition source. Thus the test
result may depend on many design features of the test system. The following characteristics of the ignition
source should be taken into account:
a) radiant, conductive and convective properties;
b) flaming or non-flaming;
c) impingement or non-impingement of ignition source on specimen;
d) precision and quantification of measurements;
e) flame stability.
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6.7 Specimen conditioning and preparation
Specimen conditioning and preparation can be of extreme importance in the fire testing of plastics materials
and products. Such preparation covers selection, sampling and the cutting-out and conditioning of the
specimens. Conditioning is important because variations in the moisture content of specimens will affect the
test results.
It is important to remove moulding flash and other similar adventitious residues from the surfaces and edges
of specimens.
The initial temperature of the specimen may influence its ease of ignition in the test.
Particular attention should be paid to thermo-formed test specimens. The conditions of the thermo-forming
operation, such as injection moulding or extrusion, should be rigorously controlled in order to minimize and, if
possible, eliminate any specimen-to-specimen variations in residual stress, anisotropy, specific gravity and
degree of crystallinity. All of these variables influence the thermo-mechanical properties of the specimen and
consequently its response to the application of heat from the fire-test ignition source.
6.8 Practical advice on contingency operating procedures in the event of specimen
collapse or deformation on exposure to heat from the ignition source
Problems arise in the fire testing of many plastics because of common thermo-mechanical effects such as
specimen slumping and sagging as well as edge effects such as the curling of the thin specimens towards or
away from the ignition source.
Interpreting test results can also be problematical when the operator has to cope with and report variations in
incident flux and/or ignition conditions (impingement/non-impingement of the ignition source) because of
changes in the source-to-specimen distance. Examples of other problem areas are interpretation of observed
non-ignition of the specimen due to its shrink-back from the ignition source and interpreting the effects on the
test result of restraining and supporting devices such as clamps, grids and wires and the masking of specimen
edges.
Such behaviour of the specimen should be reported by the operator in the test report. If the effect is so
extreme as to make it impossible to obtain test data, this should be reported as the reason why the test could
not be carried out.
Thermo-mechanical specimen responses in fire tests on plastics may give rise to localized withdrawal of the
specimen from contact with the ignition source as a result of accelerated stress relaxation within the specimen
under the influence of heat from the ignition source. These effects may manifest themselves in various ways,
depending on the chemical and physical nature of the specimen, its dimensions and its orientation as
determined by the specified test procedure. Examples are:
shrinking;
curling;
sagging;
slumping.
Gravitational effects on the test specimen are determined by its mass, dimensions and orientation. Depending
on these factors, the effect of gravity may result in sagging or slumping of the specimen. These effects may
aggravate or attenuate specimen deformation caused by internal thermo-mechanical stress-relaxation
processes. It may be noted in this connection that problems of slumping of thermoplastics specimens have
been resolved by ISO/TC 61/SC 4 in ISO 5659-2.
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6.9 Problem-solving approaches to complications caused by melting effects in
thermoplastics
Melting effects can include flaming and non-flaming drip formation, adhesion of the specimen to an ignition
source such as a glow-wire, and melt-pool formation below the test specimen, which may be feeding fuel into,
or away from, the ignition zone.
If the test conditions correspond to foreseeable end-use scenarios, these results should be reported because
they are relevant to hazard and risk assessment. If there is no likely relevance of the test conditions to the end
use, it should be reported that the test could not be carried out as specified, and an alternative test procedure
should be selected.
6.10 Advantages and disadvantages of scale in fire tests
6.10.1 General
Difficulties are often experienced in extrapolating upwards from small-scale to large-scale performance, for
there are always implications to be taken into account in the trade-off between test precision and test
relevance to end-use hazard assessment.
6.10.2 Large-scale, full-scale and real-scale tests
Such tests may offer the only available realistic assessment of the gross effects of thermal deformation and
gravity and the effects of fixtures and joints under end-use conditions in real fires. This raises questions about
the acceptability of small-scale test data on parts of products (or on materials used in products) given that
these effects play a key role in the fire safety of the product in its application scenario.
The large-scale ISO 9705 room/corner test has been used to validate the cone calorimeter for wall and ceiling
linings; it is the reference scenario for European Union classification of building products. Other reference
scenarios include large rooms, ducts, corridors, stair-wells and façades.
The advantage of large-scale tests is their relevance to end-use hazard assessment.
Their disadvantages lie in the operational hazards involved, including safety and environmental aspects, their
cost and their uncertain reproducibility.
6.10.3 Intermediate-scale tests
The major benefits of intermediate-scale tests are associated with their ability to reflect more accurately the
fire conditions of real fires than small-scale tests; for example:
Specimen mounting: Due to the larger test apparatus, specimens can incorporate more readily end-use
fixtures, joints and air-gaps. In addition, thick and/or profiled products may be accommodated. This capability
is valuable for sandwich panels, which can be up to 200 mm thick and may be faced with steel sheet
containing 150-mm-deep profiles. It is also valid for pipes, pipe insulation, cable trays, G
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