FprEN ISO 5659
(Main)Plastics - Smoke generation - Determination of optical density by a single-chamber test (ISO/FDIS 5659:2025)
Plastics - Smoke generation - Determination of optical density by a single-chamber test (ISO/FDIS 5659:2025)
ISO 5659-2:2017 specifies a method of measuring smoke production from the exposed surface of specimens of materials or composites. It is applicable to specimens that have an essentially flat surface and do not exceed 25 mm in thickness when placed in a horizontal orientation and subjected to specified levels of thermal irradiance in a closed cabinet with or without the application of a pilot flame. This method of test is applicable to all plastics.
It is intended that the values of optical density determined by this test be taken as specific to the specimen or assembly material in the form and thickness tested and are not to be considered inherent, fundamental properties.
The test is intended primarily for use in research and development and fire safety engineering in buildings, trains, ships, etc. and not as a basis for ratings for building codes or other purposes. No basis is provided for predicting the density of smoke that can be generated by the materials upon exposure to heat and flame under other (actual) exposure conditions. This test procedure excludes the effect of irritants on the eye.
Kunststoffe - Rauchentwicklung - Bestimmung der optischen Dichte durch Einkammerprüfung (ISO/FDIS 5659:2025)
Dieses Dokument legt ein Verfahren zur Messung der Rauchentwicklung auf der freiliegenden Oberfläche von Probekörpern aus Werkstoffen oder Verbundstoffen fest. Das Verfahren ist anwendbar für Probekörper mit einer im Wesentlichen ebenen Oberfläche und einer Dicke von höchstens 25 mm, die horizontal angeordnet und in einer geschlossenen Prüfkammer mit oder ohne Anwendung einer Zündflamme einer Wärmebestrahlung mit einer bestimmten Intensität ausgesetzt werden. Dieses Prüfverfahren ist anwendbar für alle Kunststoffe.
Es wird davon ausgegangen, dass die Werte der nach dieser Prüfung bestimmten optischen Dichte für den Werkstoff des Probekörpers oder vorgefertigten Teils in der untersuchten Form und Dicke als spezifisch angesehen werden und nicht als werkstoffspezifische, grundlegende Eigenschaften.
Die Prüfung ist in erster Linie für die Anwendung in der Forschung und Entwicklung sowie im Brandschutzingenieurwesen von Gebäuden, Zügen, Schiffen usw. und nicht als Bewertungsgrundlage für Bauvorschriften oder sonstige Anwendungen bestimmt. Es wird keine Vorhersage für die Dichte des Rauchs, den Werkstoffe bei einer Beanspruchung durch Wärme und Flammen unter anderen (tatsächlichen) Expositionsbedingungen erzeugen können, gegeben. Dieses Prüfverfahren schließt den Einfluss von Reizstoffen auf die Augen aus.
ANMERKUNG Dieses Prüfverfahren berücksichtigt die Einschränkung der Sichtverhältnisse durch die Rauchdichte, die im Allgemeinen nicht in Beziehung zur Reizwirkung steht (siehe Anhang E).
Es wird darauf hingewiesen, dass die von einem Werkstoff ausgehende Rauchentwicklung von der Bestrahlungsstärke abhängt, die auf den Probekörper einwirkt. Die mit dem in diesem Dokument festgelegten Verfahren erhaltenen Ergebnisse beruhen auf einer Beanspruchung mit den spezifischen Bestrahlungsstärken von 25 kW/m2 und 50 kW/m2.
Plastiques - Production de fumée - Détermination de la densité optique par un essai en enceinte unique (ISO/FDIS 5659:2025)
ISO 5659-2:2017 spécifie une méthode pour le mesurage de la production de fumée provenant de la surface exposée d'éprouvettes constituées par des matériaux ou des composites. Elle est applicable à des éprouvettes qui ont une surface essentiellement plane et dont l'épaisseur est inférieure à 25 mm, lorsqu'elles sont orientées horizontalement et soumises à des niveaux spécifiés d'éclairement énergétique thermique dans une enceinte fermée, avec ou sans utilisation de flamme pilote. La présente méthode d'essai est applicable à tous les plastiques.
Les valeurs de densité optique déterminées par le présent essai sont propres au matériau de l'éprouvette ou de l'assemblage soumis à essai, sous la forme et avec l'épaisseur sélectionnées pour l'essai. Ces valeurs ne doivent pas être considérées comme révélatrices de propriétés de base, inhérentes au produit.
L'essai est principalement destiné à être utilisé en recherche et développement et en ingénierie de sécurité incendie dans les bâtiments, les trains, les navires, etc., et non en tant que base d'appréciation pour des codes de construction ou pour d'autres fins. Aucun élément fondamental n'est fourni pour prévoir la densité de la fumée susceptible d'être produite par les matériaux exposés à la chaleur et à une flamme dans d'autres conditions (réelles) d'exposition. Le présent mode opératoire d'essai ne traite pas de l'effet des irritants sur les yeux.
Polimerni materiali - Nastajanje dima - Določanje optične gostote s preskusom v enojni preskusni komori (ISO/FDIS 5659:2025)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN ISO 5659:2024
01-november-2024
Polimerni materiali - Nastajanje dima - Določanje optične gostote s preskusom v
enojni preskusni komori (ISO/DIS 5659:2024)
Plastics - Smoke generation - Determination of optical density by a single-chamber test
(ISO/DIS 5659:2024)
Kunststoffe -Rauchentwicklung -Bestimmung der optischen Dichte durch
Einkammerprüfung (ISO/DIS 5659:2024)
Plastiques - Production de fumée - Détermination de la densité optique par un essai en
enceinte unique (ISO/DIS 5659:2024)
Ta slovenski standard je istoveten z: prEN ISO 5659
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
oSIST prEN ISO 5659:2024 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
oSIST prEN ISO 5659:2024
oSIST prEN ISO 5659:2024
DRAFT
International
Standard
ISO/DIS 5659
ISO/TC 61/SC 4
Plastics — Smoke generation —
Secretariat: BSI
Determination of optical density by
Voting begins on:
a single-chamber test
2024-09-26
Plastiques — Production de fumée — Détermination de la densité
Voting terminates on:
optique par un essai en enceinte unique
2024-12-19
ICS: 13.220.40; 83.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
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STANDARDS MAY ON OCCASION HAVE TO
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PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 5659:2024(en)
oSIST prEN ISO 5659:2024
DRAFT
ISO/DIS 5659:2024(en)
International
Standard
ISO/DIS 5659
ISO/TC 61/SC 4
Plastics — Smoke generation —
Secretariat: BSI
Determination of optical density by
Voting begins on:
a single-chamber test
Plastiques — Production de fumée — Détermination de la densité
Voting terminates on:
optique par un essai en enceinte unique
ICS: 13.220.40; 83.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 5659:2024(en)
ii
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of the test . 3
5 Suitability of a material or product for testing . 3
5.1 Material or product geometry .3
5.2 Surface characteristics .3
5.3 Asymmetrical products .3
6 Specimen construction and preparation . 4
6.1 Number of specimens .4
6.2 Size of specimens .4
6.3 Specimen preparation .4
6.4 Conditioning.5
6.5 Wrapping of specimens.5
6.6 Dimensionally unstable materials .5
7 Apparatus and ancillary equipment . 6
7.1 General .6
7.2 Test chamber .6
7.2.1 Construction.6
7.2.2 Chamber pressure control facilities .7
7.2.3 Chamber wall temperature .10
7.3 Specimen support and heating arrangements .11
7.3.1 Radiator cone.11
7.3.2 Framework for support of the radiator cone, specimen holder and heat flux
meter .11
7.3.3 Radiation shield .14
7.3.4 Heat flux meter .14
7.3.5 Specimen holder . 15
7.3.6 Pilot burner . 15
7.4 Gas supply . 15
7.5 Photometric system .16
7.5.1 General .16
7.5.2 Light source .16
7.5.3 Photo detector .16
7.5.4 Additional equipment .18
7.6 Chamber leakage .18
7.7 Cleaning materials .18
7.8 Ancillary equipment .19
7.8.1 Balance (optional) .19
7.8.2 Timing device .19
7.8.3 Linear measuring devices .19
7.8.4 Auxiliary heater .19
7.8.5 Protective equipment . .19
7.8.6 Recorder .19
7.8.7 Water-circulating device .19
7.8.8 Oxygen meter (optional) .19
8 Test environment . 19
9 Setting-up and calibration procedures .20
9.1 General . 20
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ISO/DIS 5659:2024(en)
9.2 Alignment of photometric system . 20
9.2.1 General . 20
9.2.2 Beam collimation . 20
9.2.3 Beam focusing. 20
9.3 Selection of compensating filter(s) . 20
9.4 Linearity check .21
9.5 Calibration of range-extension filter .21
9.6 Chamber leakage rate test .21
9.7 Burner calibration . 22
9.8 Radiator cone calibration . 22
9.9 Cleaning . 22
9.10 Frequency of checking and calibrating procedure . 23
10 Test procedure .23
10.1 General . 23
10.2 Preparation of test chamber. 23
10.3 Tests with pilot flame . 23
10.4 Preparation of the photometric system .24
10.5 Loading the specimen .24
10.6 Recording of light transmission .24
10.7 Observations .24
10.8 Termination of test. 25
10.9 Testing in different modes . 25
11 Expression of results .26
11.1 Specific optical density, D . 26
s
11.2 Clear-beam correction factor, D . 26
c
12 Precision .26
13 Test report .27
Annex A (normative) Calibration of heat flux meter .28
Annex B (informative) Variability in the specific optical density of smoke measured in the
single-chamber test .29
Annex C (informative) Determination of mass optical density .31
Annex D (informative) Precision data from tests on intumescent materials.36
Annex E (informative) Guidance on optical density testing .38
Annex F (informative) Specific sample preparation .45
Annex G (informative) Standard reference materials .48
Bibliography .49
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ISO/DIS 5659:2024(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent
rights identified during the development of the document will be in the Introduction and/or on the ISO list of
patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the World
Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see the following URL:
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning
behaviour.
This first edition cancels and replaces the fourth edition of ISO 5659-2:2017, which has been technically
revised.
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ISO/DIS 5659:2024(en)
Introduction
Fire is a complex phenomenon; its development and effects depend upon a number of interrelated factors.
The behaviour of materials and products depends upon the characteristics of the fire, the method of use of
the materials and the environment in which they are exposed to (see also ISO/TS 3814 and ISO 13943).
A test such as is specified in this document deals only with a simple representation of a particular aspect of
the potential fire situation, typified by a radiant heat source, and it cannot alone provide any direct guidance
on behaviour or safety in fire. A test of this type may, however, be used for comparative purposes or to
ensure the existence of a certain quality of performance (in this case, smoke production) considered to have
a bearing on fire behaviour generally. It would be wrong to attach any other meaning to results from this test.
The term “smoke” is defined in ISO 13943 as a visible suspension of solid and/or liquid particles in gases
resulting from incomplete combustion. It is one of the first response characteristics to be manifested and
should almost always be taken into account in any assessment of fire hazard as it represents one of the
greatest threats to occupants of a building or other enclosure, such as a ship or train, on fire.
The responsibility for the preparation of ISO 5659 was transferred during 1987 from ISO/TC 92 to ISO/TC 61
on the understanding that the scope and applicability of the standard for the testing of materials should not
be restricted to plastics but should also be relevant to other materials where possible, including building
materials.
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oSIST prEN ISO 5659:2024
DRAFT International Standard ISO/DIS 5659:2024(en)
Plastics — Smoke generation — Determination of optical
density by a single-chamber test
1 Scope
This document specifies a method of measuring smoke production from the exposed surface of specimens
of materials or composites. It is applicable to specimens that have an essentially flat surface and do not
exceed 25 mm in thickness when placed in a horizontal orientation and subjected to specified levels of
thermal irradiance in a closed cabinet with or without the application of a pilot flame. This method of test is
applicable to all plastics.
It is intended that the values of optical density determined by this test be taken as specific to the specimen
or assembly material in the form and thickness tested and are not to be considered inherent, fundamental
properties.
The test is intended primarily for use in research and development and fire safety engineering in buildings,
trains, ships, etc. and not as a basis for ratings for building codes or other purposes. No basis is provided
for predicting the density of smoke that can be generated by the materials upon exposure to heat and flame
under other (actual) exposure conditions. This test procedure excludes the effect of irritants on the eye.
NOTE This test procedure addresses the loss of visibility due to smoke density, which generally is not related to
irritancy potency (see Annex E).
It is emphasized that smoke production from a material varies according to the irradiance level to which the
specimen is exposed. The results yielded from the method specified in this document are based on exposure
2 2
to the specific irradiance levels of 25 kW/m and 50 kW/m .
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 13943, Fire safety — Vocabulary
ISO 14934-3, Fire tests — Calibration and use of heat flux meters — Part 3: Secondary calibration method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1
assembly
fabrication of materials (3.6) and/or composites (3.2)
Note 1 to entry: Sandwich panels are an example of an assembly.
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
Note 2 to entry: The assembly may include an air gap.
3.2
composite
combination of materials (3.6) which are generally recognized in building construction as discrete entities
Note 1 to entry: Coated or laminated materials are examples of composites.
3.3
essentially flat surface
surface which does not deviate from a plane by more than 1 mm
3.4
exposed surface
surface of the product (3.9) subjected to the heating conditions of the test
3.5
irradiance
radiant flux incident on an infinitesimal element of the surface containing the point divided by the area of
that element
3.6
material
basic single substance or uniformly dispersed mixture
Note 1 to entry: Metal, stone, timber, concrete, mineral fibre and polymers are examples.
3.7
mass optical density
MOD
measure of the degree of opacity of smoke in terms of the mass loss of the material (3.6)
3.8
optical density of smoke
D
measure of the degree of opacity of smoke, taken as the negative common logarithm of the relative
transmission of light
3.9
product
material (3.6), composite (3.2) or assembly (3.1) about which information is required
3.10
specific optical density
D
s
optical density multiplied by a factor which is calculated by dividing the volume of the test chamber by the
product (3.9) of the exposed area of the specimen (3.11) and the path length of the light beam
Note 1 to entry: See 11.1.1.
3.11
specimen
representative piece of the product to be tested together with any substrate or surface coating
Note 1 to entry: The specimen may include an air gap.
3.12
intumescent material
Material (3.6), that expands in excess of normal thermal expansion under the action of heat normally
generated by the fire.
Note 1 to entry: Generally, a material developing an expanded structure of thickness >10 mm during the test, with the
cone heater 25 mm from the specimen, is considered as intumescent material.
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
Note 2 to entry: Definition adapted from ISO 10294-5.
4 Principles of the test
Specimens of the product are mounted horizontally within a chamber and exposed to thermal radiation on
their upper surfaces at selected levels of constant irradiance up to 50 kW/m .
The smoke evolved is collected in the chamber, which also contains photometric equipment. The attenuation
of a light beam passing through the smoke is measured. The results are reported in terms of specific optical
density.
5 Suitability of a material or product for testing
5.1 Material or product geometry
5.1.1 The method is applicable to essentially flat materials, products, composites or assemblies not
exceeding 25 mm in thickness.
5.1.2 The method is sensitive to small variations in geometry, surface orientation, thickness (either overall
or of the individual layers), mass and composition of the material, and so the results obtained by this method
only apply to the thickness of the material or product as tested.
5.1.3 It is not possible to calculate the specific optical density of one thickness of a material or product
from the specific optical density of another thickness of the material or product.
5.2 Surface characteristics
A material or product having one of the following properties is suitable for testing:
a) an essentially flat exposed surface;
b) a surface irregularity which is evenly distributed over the exposed surface provided that
1) at least 50 % of the surface of a representative 100 mm area lies within a depth of 10 mm from a
plane taken across the highest points on the exposed surface or
2) for surfaces containing cracks, fissures, or holes not exceeding 8 mm in width or 10 mm in depth, the
total area of such cracks, fissures, or holes at the surface does not exceed 30 % of a representative
100 mm area of the exposed surface.
When an exposed surface does not meet the requirements of either 5.2 a) or 5.2 b), the material or product
shall be tested in a modified form complying as close as possible with the requirements given in 5.2. The test
report shall state that the material or product has been tested in a modified form and clearly describe the
modification.
5.3 Asymmetrical products
It is possible that a product submitted to this test will have faces which differ or contain laminations of
different materials arranged in a different order in relation to the two faces. If either of the faces can be
exposed in use within a room, cavity, or void, both faces shall be tested.
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
6 Specimen construction and preparation
6.1 Number of specimens
6.1.1 The test sample shall comprise a minimum of 12 specimens if all four modes are to be tested: six
specimens shall be tested at 25 kW/m (three specimens with a pilot flame and three specimens without
a pilot flame) and six specimens shall be tested at 50 kW/m (three specimens with a pilot flame and three
specimens without a pilot flame).
If fewer than four modes are to be tested, a minimum of three specimens per mode shall be tested.
6.1.2 An additional number of specimens as specified in 6.1.1 shall be used for each face, in accordance
with the requirements of 5.2.
6.1.3 An additional 12 specimens (i.e. three specimens per test mode) shall be held in reserve if required
by the modes specified in 10.9.
6.1.4 In case of dimensionally unstable materials (see clause 6.6), it is necessary to make a preliminary
test with the cone heater at 50 mm from the specimen, so at least two additional specimens are required.
6.2 Size of specimens
6.2.1 The specimens shall be square, with sides measuring 75 mm ± 1 mm.
6.2.2 Materials of 25 mm nominal thickness or less shall be evaluated at their full thickness. For
comparative testing, materials shall be evaluated at a thickness of 1,0 mm ± 0,1 mm. All materials consume
oxygen when they burn in the chamber, and the smoke generation of some materials (especially rapid-
burning or thick specimens) is influenced by the reduced oxygen concentration in the chamber. As far as
possible, materials shall be tested in their end-use thickness.
6.2.3 Materials with a thickness greater than 25 mm shall be cut to give a specimen thickness of
25 mm ± 0,1 mm, in such a way that the original (uncut) face can be evaluated.
6.2.4 Specimens of multi-layer materials with a thickness greater than 25 mm, consisting of core
material(s) with facings of different materials, shall be prepared as specified in 6.2.3 (see also 6.3.2).
6.3 Specimen preparation
6.3.1 The specimen shall be representative of the material and shall be prepared in accordance with the
procedures described in 6.3.2 and 6.3.3. The specimens shall be cut, sawn, moulded or stamped from identical
sample areas of the material, and records shall be kept of their thicknesses and, if required, their masses.
6.3.2 If flat sections of the same thickness and composition are tested in place of curved, moulded or
speciality parts, this shall be stated in the test report. Any substrate or core materials for the specimens
shall be the same as those used in practice.
6.3.3 When coating materials, including paints and adhesives, are tested with the substrate or core as
used in practice, specimens shall be prepared following normal practice, and in such cases the method of
application of the coating, the number of coats and the type of substrate shall be included in the test report.
6.3.4 This test method has been found suitable for applications outside the field of plastics, or to
transformed products in their end-use shape. Such specific sampling conditions are proposed in Annex F.
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
6.4 Conditioning
6.4.1 Before the test, specimens shall be conditioned to constant mass at a temperature of (23 ± 2) °C and
a relative humidity of (50 ± 5) % in accordance with ISO 291.
Constant mass is considered to be reached when two successive weighing operations, carried out at an
interval of 24 h, do not differ by more than 0,1 % of the mass of the test piece or 0,1 g, whichever is the greater.
Materials, such as polyamides, which require more than one week of conditioning to reach equilibrium, may
be tested after conditioning for a period specified by the sponsor. This period shall not be less than one week
and shall be described in the test report.
6.4.2 While in the conditioning chamber, specimens shall be supported in racks so that air has access to all
surfaces.
Forced-air movement in the conditioning chamber may be used to assist in accelerating the conditioning
process.
The results obtained from this method are sensitive to small differences in specimen conditioning. It is
important therefore to ensure that the requirements of 6.5 are followed carefully.
6.5 Wrapping of specimens
6.5.1 All specimens shall be covered across the back, along the edges and over the front surface periphery,
leaving a central exposed specimen area of 65 mm × 65 mm, using a single sheet of aluminium foil
(approximately 0,04 mm thick) with the dull side in contact with the specimen. Care shall be taken not to
puncture the foil or to introduce unnecessary wrinkles during the wrapping operation. The foil shall be
folded in such a way as to minimize losses of any melted specimen material at the bottom of the specimen
holder. After mounting the specimen in its holder, any excess foil along the front edges shall be trimmed off.
6.5.2 Wrapped specimens of thickness up to 12,5 mm shall be backed with a sheet of non-combustible
3 3
insulating board of oven-dry density 850 kg/m ± 100 kg/m and nominal thickness 12,5 mm and a layer of
low-density (nominal 65 kg/m ) refractory fibre blanket under the non-combustible board.
Wrapped specimens of thickness greater than 12,5 mm but less than 25 mm shall be backed with a layer of
low-density (nominal 65 kg/m ) refractory fibre blanket.
Wrapped specimens of a thickness of 25 mm shall be tested without any backing board or refractory fibre
blanket.
6.5.3 For resilient materials, each specimen in its aluminium foil wrapper shall be installed in the holder in
such a way that the exposed surface lies flush with the inside face of the opening of the specimen holder. Materials
with uneven exposed surfaces shall not protrude beyond the plane of the opening in the specimen holder.
6.5.4 When thin impermeable specimens, such as thermoplastic films, become inflated during the test
owing to gases trapped between the film and backing, they shall be maintained essentially flat by making
two or three cuts (20 mm to 40 mm long) in the film to act as vents.
6.6 Dimensionally unstable materials
Samples that intumesce or deform so that they contact the pilot flame prior to ignition, or reach the level
of the heater base plate after ignition, shall be tested with a separation of 50 mm between the base plate of
the cone heater and the upper surface of the specimen. In this case the heater calibration (see 9.8) shall be
performed with the heat flux meter positioned 50 mm below the cone heater base plate. It shall be stressed
that the time to ignition measured with this separation is not comparable to that measured with the
separation of 25 mm. If, when tested with a separation of 50 mm between the cone heater base plate and the
upper surface of the specimen, the specimen still intumesces or deforms such that it contacts the pilot flame
oSIST prEN ISO 5659:2024
ISO/DIS 5659:2024(en)
prior to ignition, or the upper specimen surface reaches the level of the cone heater baseplate, the specimen
is not suitable for the testing to this document.
Other dimensionally unstable products, for example products that warp or shrink during testing, shall be
restrained against excessive movement. This shall be accomplished with 4 tie wires, as described below.
Metal wires of (1,0 ± 0,1) mm diameter and at least 350 mm long shall be used. The sample shall be prepared
in the standard way as described in Clause 6.3. A tie wire is then looped around the sample holder and
retainer frame assembly, so that it is parallel to and approximately 20 mm away from one of the 4 sides
of the assembly. The ends of the wire are twisted together such that the wire is pulled firmly against the
retainer frame. Excess wire is trimmed from the twisted section before testing. The 3 remaining wires shall
be fitted around the specimen holder and retainer frame assembly in a similar manner, parallel to the three
remaining sides.
Materials that distort so extensively that they cannot be held by 4 wires should be tested using the fine wire
grid made of (0,8 ± 0,1) mm with wire spacing of (20 ± 2) mm.
Materials that intumesce in a fluid phase such that molten materials overflow the edge frame or seep
between the edge frame and the specimen holder invalidate the test. Therefore, such materials should be
tested without the edge frame and should be housed in 0,1 mm thick aluminium tray wrappings which
extend 10 mm above the top edge of the test specimen.
7 Apparatus and ancillary equipment
7.1 General
The apparatus (see Figure 1) shall consist of an air-tight test chamber with provision for containing a
specimen holder, radiator cone, pilot burner, light transmission and measuring system and other, ancillary
facilities for controlling the conditions of operation during a test.
7.2 Test chamber
7.2.1 Construction
7.2.1.1 The test chamber (see Figure 1 and Figure 2) shall be fabricated from laminated panels, the
inner surfaces of which shall consist of either a porcelain enamelled metal not more than 1 mm thick or an
equivalent coated metal which is resistant to chemical attack and corrosion and capable of easy cleaning. The
internal dimensions of the chamber shall be 914 mm ± 3 mm long, 914 mm ± 3 mm high and 610 mm ± 3 mm
deep. It shall be provided with a hinged front-mounted door with an observation window and a removable
opaque door cover to the window to prevent light entering the chamber. The door of the chamber shall
occupy a complete side of the smoke chamber. A safety blow-out panel, consisting of a sheet of aluminium
foil of thickness not greater than 0,04 mm and having a minimum area of 80 600 mm , shall be provided in
the chamber, fastened in such a way as to provide an airtight seal. Other materials can be considered, as long
as they cause the panel to rupture under the same pressure conditions as the aluminium sheet.
The blow-out panel may be protected by a stainless-steel wire mesh. It is important that any such mesh is
spaced at least 50 mm from the blow-out panel to prevent any obstruction in the event of an explosion.
7.2.1.2 Two optical windows, each with a diameter of 75 mm, shall be mounted, one each in the top and
bottom of the cabinet, at the position shown in Figure 2, with their interior faces flush with the outside of
the chamber lining. The underside of the window in the floor shall be provided with an electric heater of
approximately 9 W capacity in the form of a ring, which shall be capable of maintaining the upper surface
of the window at a temperature just sufficient to minimize smoke condensation on that face (a temperature
of 50 °C to 55 °C has been found suitable) and which shall be mounted around its edge so as not to interrupt
the light path. Optical platforms 8 mm thick shall be mounted around the windows on the outside of the
chamber and shall be held rigidly in position relative to each other by three metal rods, with a diameter of at
least 12,5 mm, extending through the chamber and fastened securely to the platforms.
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