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This document is developed in accordance with the rules given in GB/T 1.1-2020 Directives for standardization — Part 1: Rules for the structure and drafting of standardizing documents.
This document replaces GB/T 2408-2008 Plastics — Determination of burning characteristics — Horizontal and vertical test. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 2408-2008:
a) Some contents of “terms and definitions” are modified (see Clause 3; Clause 3 of Edition 2008);
b) The arrangement of "Test specimen", "Method A" and "Method B" is modified, and the information related to the dimension of test specimens is added (see Clauses 7, 8 and 9; Clauses 7, 8 and 9 of Edition 2008);
c) The horizontal burning classification is modified (see 8.4; 8.4 of Edition 2008);
d) The thickness information on assigned classification of material is added [see 8.5m) and 9.5l)];
e) The judgment criteria of "burned to the holding clamp" are added (see 9.2.4);
f) The figure of "arrangement orientation of burner/operator/test specimen" (Figure 6 of Edition 2008) is deleted;
g) Figures "Clearance gauge", "Flame application", "Flame application when there are molten drips", "HB specimen gauge", "V specimen gauge (example)", "Flame front position not classified as "burned to the holding clamp”" and "Flame front position classified as “burned to the holding clamp”" are added (see Figures 6 to 12).
This standard has been redrafted and modified in relation to EC 60695-11-10:2013 Fire hazard testing — Part 11-10: Test flames — 50 W horizontal and vertical flame test methods.
In addition to a number of editorial changes, the main technical changes have been made with respect to IEC 60695-11-10:2013 and their justifications are as follows:
a) The adjustments on technical differences are made for the normative references of this standard to adapt to the technical conditions in China, which are mainly reflected in Clause 2 "Normative references”, with the following specific contents:
? IEC 60695-11-4:2011 is replaced by GB/T 5169.22-2015 which is identical to the international standard (see 6.2, 8.2.3, 9.2.2 and 9.2.3);
? ISO 295:2004 is replaced by GB/T 5471-2008 which is identical to the international standard (see 7.1);
? ISO 293:2004 is replaced by GB/T 9352-2008 which is identical to the international standard (see 7.1);
? ISO 307:2007 is replaced by GB/T 12006.1-2009 which is identical to the international standard (see 9.4);
? ISO 294 (all parts) is replaced by GB/T 17037.1-2019 and GB/T 17037.5-2020 which is modified in relation to the international standard (see 7.1);
? ISO 291:2008 (see the note in 6.7) is replaced by GB/T 2918-2018, and transferred into the bibliography;
? ISO/IEC Guide 51 and ISO/IEC Guide 104 are deleted.
b) The terms "as received", "burn", "enclosure", "fire hazard assessment", "flame retardant", "fire risk", "flame" and "ignition" are deleted, as these terms are popular terms, and some of them are marked with “verb” and “noun”, which do not meet the requirements of national standards.
c) The horizontal burning classification is modified by replacing the statement “The materials shall be classified HB, HB40 or HB75” with “The materials shall be classified HB or under HB, and may be classified HB40 or HB75" to better guide the classification, because item c) in the requirements of HB classification partially overlaps with item c) in the requirements of HB40 and HB70 classifications, and the difference in item c) between the requirements of HB40 classification and HB70 classification is obvious. (See 8.4).
For the convenience of application, the following editorial modifications are made in this standard:
a) The standard name "Fire hazard testing — Part 11-10: Test flames — 50 W horizontal and vertical flame test methods" is changed to "Plastics — Determination of burning characteristics — Horizontal and vertical test";
b) The "electrotechnical products" in the scope is modified to "plastics and nonmetallic materials".
This standard was proposed by China Petroleum and Chemical Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Plastics of Standardization Administration of China (SAC/TC 15).
This standard was firstly issued in 2008, and this edition is the first revision.
Plastics — Determination of burning characteristics — Horizontal and vertical test
1 Scope
This standard specifies laboratory test procedures intended to compare the burning behaviour of plastics and nonmetallic materials when vertically or horizontally oriented test bar specimens are exposed to a small flame ignition source with a nominal thermal power of 50 W. These test methods determine either the linear burning rate or the self-extinguishing properties of materials.
These test methods are applicable to solid and cellular materials that have an apparent density of more than 250 kg/m3, determined in accordance with GB/T 6343-2009.
Two test methods are described. Method A is a horizontal burning test and is intended to determine the linear burning rate of materials under specific test conditions. Method B is a vertical burning test and is intended to determine whether materials self-extinguish under specific test conditions.
Note 1:
ISO 9772 describes a test method for the determination of the burning characteristics to be used for materials with an apparent density of 250 kg/m3 or less.
ISO 9773 describes a test method for the determination of the burning behaviour to be used for materials that due to their thinness, either distort and/or are burned up to the holding clamp using Method B of this standard.
Note 2: Guidance on pre-selection is given in IEC 60695-1-30.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 5169.22-2015 Fire hazard testing for electric and electronic products — Part 22: Test flames — 50 W flame — Apparatus and confirmational test method (IEC 60695-11-4:2011, IDT)
GB/T 5471-2008 Plastics — Compression moulding of test specimens of thermoplastic materials (ISO 295: 2004, IDT)
GB/T 9352-2008 Plastics — Compression moulding of test specimens of thermoplastic materials (ISO 293: 2004, IDT)
GB/T 12006.1-2009 Plastics — Polyamides — Part 1: Determination of viscosity number (ISO 307:2007, IDT)
GB/T 17037.1-2019 Plastics — Injection moulding of test specimens of thermoplastic materials — Part 1: General principles, and moulding of multipurpose and bar test specimens (ISO 294-1:2017, MOD)
GB/T 17037.5-2020 Plastics — Injection moulding of test specimens of thermoplastic materials — Part 5: Preparation of standard specimens for investigating anisotropy (ISO 294-5:2017, IDT)
ISO 9773:1998
/AMD 1:2003 Plastics — Determination of burning behaviour of thin flexible vertical specimens in contact with a small-flame ignition source — Amendment 1: Specimens
ISO 16012:2015 Plastics — Determination of linear dimensions of test specimens
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
afterflame
flame that persists after the ignition source has been removed under specified test conditions
3.2
afterflame time
length of time for which an afterflame persists under specified test conditions
Note to entry: Designated in Method B of this standard by the parameters t1 and t2.
3.3
afterglow
persistence of glowing combustion after both removal of the ignition source and the cessation of any flaming combustion under specified test conditions or without flame
3.4
afterglow time
length of time which an afterglow persists under specified test conditions
Note to entry: Designated in Method B of this standard by the parameter t3.
3.5
burning behaviour
response of a test specimen, when it burns under specified conditions, to examination of reaction to fire or fire resistance
3.6
draught-free environment
space in which the results of experiments are not significantly affected by the local air speed
Note to entry: A qualitative example is a space in which a wax candle flame remains essentially undisturbed. Quantitative examples are small-scale fire tests in which a maximum air speed of 0.1 m/ s or 0.2 m/s is sometimes specified.
3.7
fire hazard
physical object or condition with a potential for an undesirable consequence from fire
3.8
fire test
test that measures behaviour of a fire or exposes an item to the effects of a fire
Note to entry: The results of a fire test can be used to quantify fire severity or determine the fire resistance or reaction to fire of the test specimen.
3.9
flame front
boundary of flaming combustion at the surface of a material or propagating through a gaseous mixture
3.10
flammability
ability of a material or product to burn with a flame under specified conditions
3.11
linear burning rate
burning length of material burned per unit time under specified conditions
Note 1 to entry: The typical units are metres per second (m/s).
Note 2 to entry: In this standard, units of millimetres per minute (mm/min) are used.
Note 3 to entry: It is not advisable to use the terms “burning rate” or “rate of burning”.
3.12
molten drip
falling droplet of material that has been softened or liquefied by heat
Note to entry: The droplets can be flaming or not flaming.
3.13
self-extinguish (verb)
cease combustion without being affected by an external agent
Note to entry: It is not advisable to use the term “self-extinguishing”.
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4 Principle
A rectangular bar-shaped test specimen is supported horizontally or vertically by one end and the free end is exposed to a specified test flame. The burning behaviour of the horizontally supported bar under specific test conditions is assessed by measuring the linear burning rate. The burning behaviour of the vertically supported bar under specific test conditions is assessed by measuring the afterflame and afterglow times (observing whether the materials self-extinguish), the extent of burning and the dripping of flaming particles.
5 Significance of the fire tests
5.1 Vertical and horizontal testing
Fire tests made on a material under the conditions specified can be of considerable value when comparing the relative burning behaviour of different materials, controlling manufacturing processes or assessing any change in burning characteristics. The results obtained from these fire test methods are dependent on the shape and orientation of the test specimen, on the environment surrounding the test specimen, and on the conditions of ignition.
The significant feature of these fire test methods is the arrangement of the test specimens in either a horizontal or a vertical position. These testing arrangements make it possible to distinguish between different classes of material flammability.
Note 1: The results obtained by the horizontal burning (HB) and vertical burning (V) methods are not equivalent.
Note 2: The results obtained by these methods (HB and V) are not equivalent to the 5VA and 5VB burning tests specified in GB/T 5169.17-2017 because the thermal power of the test flame in these methods is 50 W whereas the test flame in GB/T 5169.17-2017 is 500 W.
5.2 Limitations on the use of test results
Results obtained in accordance with this standard shall not be used solely to describe or appraise the fire hazard presented by a particular material under actual fire conditions. Assessment of fire hazard also requires consideration of other such factors as fuel contribution, intensity of burning (rate of heat release), products of combustion and environmental factors, including the nature of the ignition source, the orientation of exposed material and ventilation conditions.
5.3 Physical properties that can affect burning behaviour
Burning behaviour, as measured by these test methods, is affected by such factors as density, any anisotropy of the material and the thickness of the test specimen.
5.4 Shrinkage and distortion
Certain test specimens may shrink from or be distorted by the applied flame without igniting. In this event, additional test specimens at the same thickness will be required to obtain valid results. If valid results at that thickness cannot be obtained, these materials at that specific tested thickness are not suitable for evaluation by these test methods.
To be able to determine a flammability classification for thin flexible test specimens, and in cases where more than one test specimen shrinks from the applied flame without igniting, ISO 9773:1998/AMD 1:2003 provides a suitable test method.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Significance of the fire tests
6 Apparatuses
7 Test specimens
8 Test method A——Horizontal burning test
9 Test method B——Vertical burning test
Annex A (Informative) Precision of test method A
Annex B (Informative) Precision of test method B
Bibliography
