EN ISO 4589-2:2017

SLOVENSKI STANDARD
01-julij-2017
1DGRPHãþD
SIST EN ISO 4589-2:2000
SIST EN ISO 4589-2:2000/A1:2006
3ROLPHUQLPDWHULDOL'RORþDQMHJRUOMLYRVWLVNLVLNRYLPLQGHNVRPGHO3UHVNXV
SULVREQLWHPSHUDWXUL,62
Plastics - Determination of burning behaviour by oxygen index - Part 2: Ambient-
temperature test (ISO 4589-2:2017)
Kunststoffe - Bestimmung des Brennverhaltens durch den Sauerstoff-Index - Teil 2:
Prüfung bei Umgebungstemperatur (ISO 4589-2:2017)
Plastiques - Détermination du comportement au feu au moyen de l'indice d'oxygène -
Partie 2: Essai à la température ambiante (ISO 4589-2:2017)
Ta slovenski standard je istoveten z: EN ISO 4589-2:2017
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4589-2
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2017
EUROPÄISCHE NORM
ICS 13.220.40; 83.080.01 Supersedes EN ISO 4589-2:1999
English Version
Plastics - Determination of burning behaviour by oxygen
index - Part 2: Ambient-temperature test (ISO 4589-
2:2017)
Plastiques - Détermination du comportement au feu au Kunststoffe - Bestimmung des Brennverhaltens durch
moyen de l'indice d'oxygène - Partie 2: Essai à la den Sauerstoff-Index - Teil 2: Prüfung bei
température ambiante (ISO 4589-2:2017) Umgebungstemperatur (ISO 4589-2:2017)
This European Standard was approved by CEN on 13 March 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4589-2:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 4589-2:2017) has been prepared by Technical Committee ISO/TC 61 "Plastics"
in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by
NBN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by November 2017 and conflicting national standards
shall be withdrawn at the latest by November 2017.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
This document supersedes EN ISO 4589-2:1999.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 4589-2:2017 has been approved by CEN as EN ISO 4589-2:2017 without any
modification.
INTERNATIONAL ISO
STANDARD 4589-2
Second edition
2017-04
Plastics — Determination of burning
behaviour by oxygen index —
Part 2:
Ambient-temperature test
Plastiques — Détermination du comportement au feu au moyen de
l’indice d’oxygène —
Partie 2: Essai à la température ambiante
Reference number
ISO 4589-2:2017(E)
©
ISO 2017
ISO 4589-2:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
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CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 Test chimney . 2
5.2 Test specimen holder. 2
5.3 Gas supplies . 6
5.4 Gas control devices . 7
5.5 Oxygen analyser . 7
5.6 Flame igniter . 7
5.7 Timing device . 7
5.8 Fume extraction system . 8
5.9 Tool for preparing rolled film . 8
6 Calibration of equipment. 8
7 Preparation of test specimens . 8
7.1 Sampling . 8
7.2 Test specimen dimensions and preparation . 9
7.3 Marking of test specimens .11
7.3.1 General.11
7.3.2 Marks for testing by top surface ignition .11
7.3.3 Marks for testing by propagating ignition .11
7.4 Conditioning .11
8 Procedure for determination of oxygen index .12
8.1 General .12
8.2 Setting up the apparatus and test specimen .12
8.3 Igniting the test specimen .13
8.3.1 General.13
8.3.2 Procedure A — Top surface ignition .13
8.3.3 Procedure B — Propagating ignition .13
8.4 Assessing the burning behaviour of individual test specimens . .13
8.5 Selecting successive volume fractions of oxygen .14
8.6 Determining the preliminary volume fraction of oxygen .15
8.7 Volume fraction of oxygen changes .15
9 Calculations and expression of results .16
9.1 Oxygen index.16
9.2 Determination of k .17
9.3 Standard deviation of oxygen volume fraction measurements .17
9.4 Precision of results .18
10 Comparison with a specified minimum value of the oxygen index (short procedure) .19
10.1 General .19
10.2 Setting up the apparatus and test specimen .19
10.3 Igniting the test specimen .19
10.4 Assessing the burning behaviour of the test specimens .19
10.5 Expressing of results .19
11 Test report .19
Annex A (normative) Calibration of equipment .20
ISO 4589-2:2017(E)
Annex B (normative) Calculation of volume fraction of oxygen .22
Annex C (informative) Typical test results sheet .23
Annex D (informative) Results obtained by interlaboratory trials on type VI specimens .25
Annex E (informative) Precision data obtained from an interlaboratory trial carried out
in 1978-1980 .26
Bibliography .27
iv © ISO 2017 – All rights reserved

ISO 4589-2:2017(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.
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: w w w . i s o .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 4, Burning
behaviour.
This second edition cancels and replaces the first edition (ISO 4589-2:1996), which has been technically
revised. It also incorporates the Amendment ISO 4589-2:1996/Amd.1:2005.
A list of all parts in the ISO 4589 series can be found on the ISO website.
ISO 4589-2:2017(E)
Introduction
Oxygen index (OI) results obtained using the methods described in this document can provide a sensitive
measure of the burning characteristics of materials under certain controlled laboratory conditions, and
hence may be useful for quality control purposes. The results obtained are dependent upon the shape,
orientation and isolation of the test specimen and the conditions of ignition. For particular materials or
applications, it may be necessary or appropriate to specify different test conditions. Results obtained
from test specimens of differing thickness or by using different ignition procedures may not be
comparable and no correlation with flammability behaviour under other fire conditions is implied.
Results obtained in accordance with this document are not applicable to describe or appraise the fire
hazard presented by a particular material or shape under actual fire conditions, unless used as one
element of a fire risk assessment that takes into account all of the factors pertinent to the assessment of
the fire hazard of a particular application for the material.
For assessing the flame propagation properties of cellular materials of density < 100 kg/m , attention
is drawn to the method described in ISO 3582.
vi © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 4589-2:2017(E)
Plastics — Determination of burning behaviour by
oxygen index —
Part 2:
Ambient-temperature test
1 Scope
This document specifies methods for determining the minimum volume fraction of oxygen, in
admixture with nitrogen, that will support combustion of small vertical test specimens under specified
test conditions. The results are defined as oxygen index (OI) values.
Methods are provided for testing materials that are self-supporting in the form of vertical bars or sheets
up to 10,5 mm thick. These methods are suitable for solid, laminated or cellular materials characterized
by an apparent density 100 kg/m or greater. The methods might also be applicable to some cellular
materials having an apparent density of less than 100 kg/m . A method is provided for testing flexible
sheets or film materials while supported vertically.
For comparative purposes, a procedure is provided for determining whether or not the OI of a material
lies above some specified minimum value.
NOTE It might not be possible to apply these methods satisfactorily to materials that exhibit high levels of
shrinkage when heated, e.g. highly oriented thin film.
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 291:2008, Plastics — Standard atmospheres for conditioning and testing
ISO 2859-1, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 2859-2, Sampling procedures for inspection by attributes — Part 2: Sampling plans indexed by limiting
quality (LQ) for isolated lot inspection
ISO 4589-1, Plastics — Determination of burning behaviour by oxygen index — Part 1: General requirements
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
for the determination of repeatability and reproducibility of a standard measurement method
ISO 7823-1, Plastics — Poly(methyl methacrylate) sheets — Types, dimensions and characteristics —
Part 1: Cast sheets
ISO 13943, Fire safety −Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4589-1 and ISO 13943 apply.
ISO 4589-2:2017(E)
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Principle
A small test specimen is supported vertically in a mixture of oxygen and nitrogen flowing upwards
through a transparent chimney. The upper end of the specimen is ignited and the subsequent burning
behaviour of the specimen is observed to compare the period for which burning continues, or the length
of specimen burned, with specified limits for such burning. By testing a series of specimens in different
volume fractions of oxygen, the OI is estimated (see 8.7).
Alternatively, for comparison with a specified OI, three test specimens are tested using the relevant
volume fraction of oxygen, at least two of which are required to given an “O” response (see 8.4) in order
to meet the specified OI.
5 Apparatus
5.1 Test chimney
The test chimney shall consist of a heat-resistant glass tube supported vertically on a base through
which oxygen-containing gas mixtures can be introduced (see Figure 1).
The recommended dimensions of the chimney are 450 mm to 500 mm height and 75 mm to 100 mm
inside diameter.
The upper outlet shall be restricted as necessary by an overhead cap having an outlet small enough to
produce an exhaust velocity of at least 90 mm/s from that outlet. The flow rate shall be calculated by
using the formula found in A.2.
NOTE 1 Measurement of flow rate or flow speed at the specimen position helps for checking gas leaks.
NOTE 2 A cap converging to an outlet of 40 mm diameter at a level at least 10 mm above the top of the
cylindrical chimney has been found satisfactory.
Chimneys of other dimensions, with or without restricted outlets, are suitable for use, if shown to give
equivalent results. The bottom of the chimney, or the base upon which the chimney is supported, shall
incorporate a device for evenly distributing the gas mixture entering the chimney. The preferred device
comprises a diffuser and a mixing chamber with metal foil (honeycomb) or glass beads. Other devices,
such as radial manifolds are suitable for use, if shown to give equivalent results. The mounting of a
porous screen below the level of the specimen holder is helpful to prevent falling combustion debris
from fouling the gas entry and distribution paths. One option is to construct the chimney in such a way
that it can be divided in half, so as to make the setting of samples and cleaning easier.
The use of a levelling device and indicator incorporated within the chimney support will aid vertical
alignment of the chimney and of a test specimen supported therein. If a dark background is provided,
this will aid the observation of flames within the chimney.
5.2 Test specimen holder
The specimen holder shall be suitable for supporting a specimen vertically in the centre of the chimney.
For self-supporting materials, the specimen shall be held by a small clamp, which is at least 15 mm away
from the nearest point at which it is possible that the specimen will burn before the extent-of-burning
criterion is exceeded. For supported film or sheet test specimens, the specimen shall be supported by
both vertical edges in a frame equivalent to that illustrated by Figure 6, with reference marks at 20 mm
and 100 mm below the top of the frame.
2 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
It is recommended that the profile of the holder and its support is smooth to minimize induction of
turbulence in the rising flow gas.
Dimensions in millimetres
Key
1 chimney 6 optional temperature measurement device
2 chimney cap 7 tube
3 specimen holder 8 test specimen
4 wire-mesh debris screen 9 oxygen/nitrogen mixture
5 diffuser and a mixing chamber 10 flame igniter
Figure 1 — Typical apparatus for determination of oxygen index
ISO 4589-2:2017(E)
Key
1 oxygen 6 flow meter
2 nitrogen 7 reference gas
3 needle valve 8 to exhaust
4 calibrated flow meter 9 to chimney
5 oxygen analyser
Figure 2 — Typical flow system incorporating the elements described in 5.4, a)
Key
1 oxygen 6 oxygen analyser
2 nitrogen 7 flow meter
3 needle valve 8 reference gas
4 pressure gauge 9 to exhaust
5 calibrated orifice 10 to chimney
Figure 3 — Typical flow system incorporating the elements described in 5.4, b)
4 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
Key
1 oxygen 6 flow meter
2 nitrogen 7 reference gas
3 needle valve 8 to exhaust
4 calibrated flow meter 9 to chimney
5 oxygen analyser
Figure 4 — Diagram of typical flow system incorporating the elements described in 5.4, c)
Key
1 oxygen 6 flow meter
2 nitrogen 7 reference gas
3 calibrated mass flow controller 8 to exhaust
4 oxygen analyser 9 to chimney
5 needle valve
Figure 5 — Typical flow system incorporating the elements described in 5.4, d)
ISO 4589-2:2017(E)
Dimensions in millimetres with tolerances ± 0,25 mm
Key
1 upper reference mark
2 lower reference mark
NOTE The test specimen is held securely along both upright edges between forks made of stainless steel.
Figure 6 — Support frame for non-self-supporting test specimens
5.3 Gas supplies
The gas supplies shall comprise pressurized sources of oxygen and/or nitrogen not less than 98 %
(mass fraction) pure and/or clean air [containing 20,9 % (volume fraction) oxygen], as appropriate.
The moisture content of the gas mixture entering the chimney shall be < 0,1 % (mass fraction), unless
the results have been shown to be insensitive to higher moisture levels in the gas mixture. The gas
supply system shall incorporate a drying device, or provision for monitoring or sampling the gas supply
for moisture content, unless the moisture content of the gas supplies is known to be acceptable.
6 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
The constituent gas supply lines shall be linked in a manner which thoroughly mixes the gases, before
they enter the gas distribution device at the base of the chimney, so that the variation in volume fraction
of oxygen in the gas mixture rising in the chimney, below the level of the test specimen, is < 0,2 %.
NOTE Bottled oxygen or nitrogen does not always contain < 0,1 % (mass fraction) of water; moisture
contents of 0,003 % (mass fraction) to 0,01 % (mass fraction) are typical for commercial supplies as filled bottles
of purity ≥ 98 % (mass fraction), but as such bottled gases are depressurized to below about 1 MPa, the moisture
content of the gas drawn off may rise above 0,1 % (mass fraction).
5.4 Gas control devices
The gas control devices shall be suitable for setting the volume fraction of oxygen in the gas mixture
entering the chimney with a resolution of 0,1 % of the mixture and for adjusting the volume fraction with
an accuracy of ± 0,2 % of the mixture when the gas velocity within the chimney is 40 mm/s ± 2 mm/s at
23 °C ± 2 °C. The flow rate shall be calculated by using the formula found in A.2.
NOTE 1 It is found suitable to measure the temperature of gas mixture inside the column by an optional
temperature measurement device shown in Figure 1.
NOTE 2 Systems of measurement and control that have proved satisfactory include the following:
a) needle valves on individual and mixed gas supply lines, a paramagnetic oxygen analyser that continuously
samples the mixed gas, and a calibrated flow meter to indicate when the gas flow through the chimney is
within the required limits (see Figure 2);
b) calibrated orifices, gas pressure regulators and pressure gauges on the individual gas supply lines, and an
oxygen analyser that continuously samples the mixed gas (see Figure 3);
c) needle valves and calibrated flow meters on the individual gas supply lines, and an oxygen analyser that
continuously samples the mixed gas (see Figure 4);
d) calibrated mass flow controllers on the individual gas supply lines, and an oxygen analyser that continuously
samples the mixed gas (see Figure 5).
NOTE 3 Any system incorporating appropriate needle valves, and/or calibrated orifices, and/or gas pressure
regulators, and/or calibrated flow meters in conjunction with a suitable means to measure the volume fraction of
oxygen to the requirements of 5.3 and 5.4 has been found suitable for the performance of this test procedure.
5.5 Oxygen analyser
The oxygen analyser shall be suitable for measuring the volume fraction of oxygen in the gas mixture
entering the chimney with a resolution of 0,1 % and an accuracy of ± 0,1 % of the mixture.
NOTE 1 It has been found that paramagnetic oxygen analysers meet the accuracy requirements.
NOTE 2 In case the volume fraction of oxygen around the position of the specimen differs from that controlled
at the air supply line, troubleshooting will be necessary.
5.6 Flame igniter
The flame igniter shall comprise a tube that can be inserted into the chimney to apply to the test
specimen a flame issuing from an outlet of 2 mm ± 1 mm diameter at the end of the tube.
The flame fuel shall be propane without premixed air. The purity of the propane gas shall be not less
than 98 %. The fuel supply shall be adjusted so that, for the set volume fraction of oxygen, the total
flame height is 16 mm ± 4 mm when the tube is vertical within the chimney.
The use of a flame height gauge is recommended.
5.7 Timing device
The timing device shall be capable of measuring periods up to 5 min with an accuracy of ± 0,5 s.
ISO 4589-2:2017(E)
5.8 Fume extraction system
The fume extraction system shall be capable of providing sufficient ventilation or exhaust to remove
fumes or soot expelled from the chimney without disrupting the gas flow rate or temperatures in the
chimney.
WARNING — Take suitable precautions to protect personnel from noxious materials or burns
during testing or cleaning operations.
5.9 Tool for preparing rolled film
The tool for preparing rolled film shall consist of a stainless-steel rod of 2 mm diameter, with a slit in
one end (see Figure 7).
6 Calibration of equipment
For compliance with this method, calibrate the equipment periodically in accordance with the
instructions given in Annex A so that the maximum interval between recalibration and use conforms to
the periods stated in Table 1.
Table 1 — Equipment calibration frequencies
Item Maximum period
Leak tests for gas system joints (as required by A.1)
a) for joints disturbed during use or cleaning of the apparatus Immediately
b) for undisturbed equipment 6 months
Gas flow rates (as required by A.2) 6 months
Oxygen analyser (as required by A.3) 1 week
Performance check of complete equipment (as required by A.5) 1 month
7 Preparation of test specimens
7.1 Sampling
Obtain a sample sufficient for preparation of at least 15 test specimens. The sample shall be taken, if
relevant, in accordance with the material specification, otherwise in accordance with ISO 2859-1 or
ISO 2859-2, as applicable.
For a material for which the OI is known to be within ± 2, 15 test specimens can be sufficient. For
materials of unknown OI, or which exhibit erratic burning characteristics, between 15 and 30 test
specimens may be required.
8 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
Dimensions in millimetres
Key
1 stainless-steel rod
2 grip
3 slit to hold one end of film to be rolled
Figure 7 — Tool for preparing rolled-film specimens
7.2 Test specimen dimensions and preparation
Using, if applicable, procedures that comply with the appropriate material specification or ISO methods
for specimen preparation, mould or cut test specimens that satisfy the dimensions specified for the
most appropriate specimen form given in Table 2.
To prepare a rolled specimen from a thin film, use the tool described in 5.9. Insert one corner of the
film into the slit and then wind the film round the rod in a spiral of 45°. Ensure that the 45° angle is
maintained during the winding process so that the film reaches exactly to the end of the tool, to produce
a test piece of the correct length, as shown in Figure 7. After the winding is finished, tape the last end of
the roll while the material is still on the stainless steel rod to prevent loosening. Then pull the rod out of
the rolled film. Cut off the rolled film at a distance of 20 mm from the top end (see Figure 8).
ISO 4589-2:2017(E)
Ensure that the surfaces of the specimens are clean and free from flaws that could affect burning
behaviour, e.g. peripheral moulding flash or burrs from machining.
Note the position and orientation of test specimens with respect to any asymmetry in the sample
material.
Some material specifications may require choice and identification of the “state of the test specimen”
used; e.g. in a “defined state” or a “basic state” for a styrene-based polymer or copolymer.
In the absence of a relevant specification, one or more procedures from ISO 293, ISO 294, ISO 295,
ISO 2818 or ISO 3167 may be used.
OI results may be significantly affected by differences in ease of ignition or burning behaviour, due to
material inhomogeneity (e.g. different levels of shrinkage when heated for specimens cut in different
directions from asymmetrically oriented thermoplastics film).
If a thin film burns in such a manner that erratic combustion behaviour including heat shrinkage
and fluctuation of data results, the specimen form VI, i.e. a rolled film, should preferably be used. It
gives reproducible results, similar to those given by specimen form I. Precision data obtained by
interlaboratory trials on specimen form VI are given in Annex D.
Table 2 — Test specimen dimensions
Dimensions
Test specimen
Typical use
Length Width Thickness
a
form
mm mm mm
I 80 to 150 10 ± 0,5 4 ± 0,25 For moulding materials
II 80 to 150 10 ± 0,5 10 ± 0,5 For cellular materials
b
III 80 to 150 10 ± 0,5 ≤ 10,5 For sheet materials “as received”
Alternative size for self-supporting moulding
IV 70 to 150 6,5 ± 0,5 3 ± 0,25
or sheet materials, for electrical purposes
b
V 140 52 ± 0,5 ≤ 10,5 For flexible film or sheet
−5
For thin film “as received”; limited to the film
c d
VI 140 to 200 20 0,02 to 0,10
d
that can be rolled by the specified rod
a
Test specimens of forms I, II, III and IV are suitable for materials that are self-supporting at these dimensions. Test
specimens of form V are suitable for materials that require support during testing.
b
Results obtained using form Ill or form V test specimens are likely to only be comparable for specimens of the same
form and thickness. It is assumed that the amount of variation in thickness for such materials will be controlled by other
standards.
c
The test specimen of form VI is suitable for a thin film that is self-supporting when it is rolled. Dimensions in the table
are of an original film from which the rolled form is made. See 7.2 for the preparation of rolled film.
d
The film is limited to thicknesses that can be rolled by the specified rod (see Figure 7). If the film is very thin, it will
potentially be necessary to combine two or more films together in the preparation of the rolled film so as to obtain results
similar to those normally obtained with specimen form VI.
10 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
Dimensions in millimetres
Key
1 tape
2 cut off
Figure 8 — Rolled specimen
7.3 Marking of test specimens
7.3.1 General
For monitoring the distance over which a specimen burns, it is convenient to mark the specimen with
transverse lines at one or more levels which are dependent upon the specimen form and the ignition
procedure to be used. Self-supporting specimens are preferably marked on at least two adjacent faces.
If wet inks are used, the marks shall be dry before the specimen is ignited.
7.3.2 Marks for testing by top surface ignition
Test specimens of form I, II, III, IV or VI to be tested in accordance with procedure A (see 8.3.2) shall be
marked 50 mm from the end to be ignited.
7.3.3 Marks for testing by propagating ignition
The reference marks for testing specimens of form V are carried by the supporting frame (see
Figure 6), but marking such specimens at 20 mm and at 100 mm from the end to be ignited will provide
convenience when testing heat-stable materials.
If specimens of forms I, II, III, IV and VI are to be tested in accordance with procedure B (see 8.3.3), they
shall be marked at 10 mm and at 60 mm from the end to be ignited.
7.4 Conditioning
Unless otherwise specified in other established standards, each test specimen shall be conditioned for
24 h at 23 °C ± 2 °C and (50 ± 5) % relative humidity. After 24 h conditioning, if the stability of the
ISO 4589-2:2017(E)
mass of the specimen reaches to 0,1 % or less changes, then allow to conduct the test. Otherwise, follow
ISO 291:2008, 8.1 to keep the specimen in conditioning chamber for at least 88 h.
Specimens of cellular materials that may contain volatile flammable material should preferably
be purged of such volatile material prior to conditioning at 23 °C and 50 % relative humidity. Test
specimens may be purged satisfactorily by pre-conditioning at 60 °C in suitable ventilated ovens for
168 h. Larger blocks of such materials may require longer pre-treatment. It is important that facilities
for cutting specimens from cellular material that may contain volatile flammable material are suitable
for the hazards involved.
8 Procedure for determination of oxygen index
8.1 General
For a shortened procedure to determine compliance relative to a specified minimum value of the OI,
without determining the actual OI of the material under test, see Clause 10.
8.2 Setting up the apparatus and test specimen
8.2.1 Maintain the ambient temperature for the test apparatus at 23 °C ± 2 °C. If necessary, keep the
test specimens in an enclosure at 23 °C ± 2 °C and (50 ± 5) % relative humidity from which each test
specimen shall be taken when required.
8.2.2 Recalibrate equipment components, if necessary (see Clause 6 and Annex A). Before conducting
a test, clean the glass chimney to maintain good visibility. If necessary, clean also the gas inlets, or inlet
screen, and the temperature sensor (if fitted).
8.2.3 Select an initial volume fraction of oxygen to be used. When possible, base this on experience
of results for similar materials. Alternatively, try to ignite a test specimen in air, and note the burning
behaviour. If the specimen burns rapidly, select an initial volume fraction of about 18 % of oxygen; if the
test specimen burns gently or unsteadily, select an initial oxygen volume fraction of about 21 %; if the
specimen does not continue to burn in air, select an initial volume fraction of at least 25 %, depending
upon the difficulty of ignition or the period of burning before extinguishing in air.
8.2.4 Ensure that the test chimney is vertical (see Figure 1). Mount a specimen vertically in the centre
of the chimney so that the top of the specimen is at least 100 mm below the open top of the chimney and
the lowest exposed part of the specimen is at least 100 mm above the top of the gas distribution device at
the base of the chimney (see Figure 1 or 6 as appropriate).
8.2.5 Set the gas mixing and flow controls so that an oxygen/nitrogen mixture at 23 °C ± 2 °C, containing
the desired volume fraction of oxygen, is flowing within the chimney at 40 mm/s ± 2 mm/s. Let the gas
flow purge the chimney for at least 30 s prior to ignition of each specimen, and maintain the flow without
change during ignition and combustion of each specimen. The flow rate shall be calculated by using the
formula found in A.2.
Record the volume fraction of oxygen used, which is measured by an oxygen analyser or calculated in
accordance with the formulae given in Annex B.
12 © ISO 2017 – All rights reserved

ISO 4589-2:2017(E)
8.3 Igniting the test specimen
8.3.1 General
Select one of two alternative ignition procedures which are dependent upon the specimen form as
follows:
a) For specimen forms I, II, III, IV and VI (see Table 2), use procedure A (top surface ignition) as
described in 8.3.2.
b) For specimen form V, use procedure B (propagating ignition) as described in 8.3.3.
Ignition shall imply, for the purposes of this document, the initiation of flaming combustion.
For tests on materials that exhibit steady burning and spread of combustion in volume fractions of
oxygen at, or close to, their OI value, or for self-supporting specimens of ≤ 3 mm thickness, procedure
B (with specimens marked in accordance with 7.3.3) can be fou
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