Clothing for protection against heat and flame — Determination of heat transmission on exposure to both flame and radiant heat

This document specifies a test method for measuring the heat transferred through horizontally mounted flame-resistant textile materials when exposed to a combination of convective and radiant heat. The exposure conditions are adjusted to be approximately a 50/50 mixture of pure convective heat and pure radiant heat. The total exposure heat flux is 84 kW/m2. This test method is applicable to any type of sheet material used either as a single layer or in a multilayer construction when all structures or sub-assemblies are made of flame-resistant materials. It does not apply to materials that are not flame resistant. This test method does not apply to the evaluation of materials exposed to any other type of thermal energy sources, such as radiant heat only or flame contact only. ISO 6942 is applicable when evaluating materials for exposure to radiant heat only. ISO 9151 is applicable when evaluating materials due to flame contact only. NOTE Some, but not all, textiles materials can ignite and continue to burn after exposure to the convective and radiant heat produced by this test method.

Vêtements de protection contre la chaleur et la flamme — Détermination de la transmission de chaleur lors de l'exposition simultanée à une flamme et à une source de chaleur radiante

General Information

Status
Published
Publication Date
07-Oct-2019
Current Stage
6060 - International Standard published
Start Date
08-Oct-2019
Due Date
09-Apr-2019
Completion Date
08-Oct-2019
Ref Project

Relations

Buy Standard

Standard
ISO 17492:2019 - Clothing for protection against heat and flame -- Determination of heat transmission on exposure to both flame and radiant heat
English language
19 pages
sale 15% off
Preview
sale 15% off
Preview

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17492
Second edition
2019-10
Clothing for protection against heat
and flame — Determination of heat
transmission on exposure to both
flame and radiant heat
Vêtements de protection contre la chaleur et la flamme —
Détermination de la transmission de chaleur lors de l'exposition
simultanée à une flamme et à une source de chaleur radiante
Reference number
ISO 17492:2019(E)
©
ISO 2019

---------------------- Page: 1 ----------------------
ISO 17492:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 17492:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
5 Apparatus . 4
6 Precautions . 8
7 Sampling . 9
7.1 Specimen dimensions . 9
7.2 Number of specimens . 9
8 Conditioning and testing atmospheres . 9
8.1 Conditioning atmosphere . 9
8.2 Testing atmosphere. 9
9 Test procedure . 9
9.1 Initial set up and calibration procedures . 9
9.1.1 Initial set up of the system and alignment of burner flames . 9
9.1.2 Initial setting of the 50/50 mix of convective and radiant heat . 9
9.1.3 Setting the radiant heat from the lamps . 9
9.1.4 Setting the total exposure heat flux .10
9.2 Sensor care .10
9.2.1 Sensor care .10
9.2.2 Sensor inspection .10
9.2.3 Surface reconditioning.10
9.3 Specimen holder care .11
9.4 Computer processing of data .11
9.5 Test specimen mounting .12
9.5.1 Single layer specimens .12
9.5.2 Multilayer assembly specimens .12
9.6 Test specimen exposure when both TPI and HTI(DE) are measured .12
9.7 Test specimen exposure when only HTI(DE) is measured .13
10 Expression of results .13
10.1 Selection of analysis method .13
10.2 Thermal protection index analysis method .13
10.2.1 Time to onset of burn injury .13
10.2.2 Thermal protection index .13
10.3 HTI(DE) analysis method .14
10.4 Response to convective and radiant heat exposure .14
11 Interlaboratory test data .14
12 Test report .14
Annex A (informative) Availability of materials .15
Annex B (informative) Basis of sensor calibration .17
Annex C (informative) Interlaboratory test data .18
Bibliography .19
© ISO 2019 – All rights reserved iii

---------------------- Page: 3 ----------------------
ISO 17492:2019(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 of 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 www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 94, Personal safety — Personal protective
equipment, Subcommittee SC 13, Protective clothing.
This second edition cancels and replaces the first edition (ISO 17492:2003), which has been technically
revised. It also incorporates the Technical Corrigendum ISO 17492:2003/Cor.1:2004. The main changes
compared with the previous edition are as follows:
— technical modifications and rewording have been made to all clauses, including to Annexes A and B;
— Clauses 5 to 12 have been renumbered;
— modifications have been made to Figures 1, 2 and 3.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2019 – All rights reserved

---------------------- Page: 4 ----------------------
ISO 17492:2019(E)

Introduction
The measurement of the thermal energy transferred from the exterior of a material to the interior
when exposed to a thermal hazard can be a significant factor in determining the level of protection or
insulation provided by an assembly. While full-scale test methods are a better means of determining
how an assembly performs, small scale tests such as those described in ISO 6942 and ISO 9151 can be
used in establishing benchmarks of performance for the materials from which these assemblies are
made. These tests enable the user of a material to anticipate how the properties of a particular material
could affect the performance of the assembly when exposed to a high heat flux.
The purpose of an assembly for thermal protection is to prevent or reduce the potential for skin burn
injury to the wearer. The performance of a product can be determined by comparing the total exposure
energy to that which is transferred through the protective material to a known point where the thermal
exposure would produce a burn injury in human tissue. The total exposure energy required to cause
the onset of a second-degree burn in human tissue is identified as the thermal protection index (TPI).
In the TPI analysis of the data, the specimen is exposed to steady heat until the energy transferred
through the specimen is equivalent to the energy that would cause the onset of a second-degree burn
injury (e.g. a blister).
Other uses include comparison of the insulation from a high-temperature exposure in terms other than
the response of human tissue to heat exposure. For these uses, an alternate method of evaluating the
heat transfer is provided. The total energy transferred that causes a temperature rise of the copper
sensor by 12 °C and 24 °C is determined as the heat transfer index (HTI). In the HTI analysis of the data,
the specimen is exposed to heat until a specified amount of energy is transferred. This is a measure of
the insulation performance and thermal capacity of the specimen.
Unlike what is described in ISO 6942 or ISO 9151, the heat source in this test method is approximately
50 % radiant heat and 50 % convective heat. This equalized radiant/convective output is set to a
2
thermal energy exposure having a heat flux of 84 kW/m . The magnitude of this heat flux is intended
to determine the performance of the specimen when exposed to both the high temperature radiation
and hot gases that exist in actual fire situations. The level of this heat flux represents a moderately high
industrial or emergency fire-fighting exposure that requires the use of a protective material.
This document can be used to measure and describe the properties of materials, products or
assemblies in response to both convective and radiant heat under controlled laboratory conditions. It
is not recommended to use this document to describe or appraise a fire hazard or fire risk of materials,
products or assemblies under actual fire conditions. However, the results of this test method can be
used as elements of a fire-risk assessment that takes into account all of the factors pertinent to an
assessment of the fire hazard of a particular end use.
NOTE 1 This test method does not necessarily correlate to the heat-insulation performance of vertically
oriented flame-resistant textile materials when exposed to convective and radiant heat or used in actual clothing
configurations.
NOTE 2 The performance of materials made of flame-resistant fibres can be determined by the amount of
heat energy transferred through the specimen and by observing any changes affected by the exposure on the
specimen. The TPI and the HTI measure the accumulated thermal energy received by a sensor, which is an
indication of the ability of the material to inhibit the transfer of heat.
NOTE 3 A human tissue burn (blister) is predicted to result when the total thermal energy transmitted by the
material reaches the second-degree burn threshold identified by the Stoll curve.
NOTE 4 The TPI or the HTI for flame-resistant materials can be used to establish anticipated thermal
performance levels for single layer or multilayer constructions or assemblies.
NOTE 5 Different specimen-mounting conditions, which are determined by the number of layers of material in
the test specimen, are provided in this method. Each condition emphasizes a different thermal characteristic of
the sample and represents the way in which the material is used in the end-use application.
© ISO 2019 – All rights reserved v

---------------------- Page: 5 ----------------------
ISO 17492:2019(E)

NOTE 6 The spaced configuration, with a spacer placed between the back surface of the specimen and the
sensor, reflects applications in which there is an air space or gap between the specimen and the protected
surface. This spaced configuration also eliminates the cooling effect, which occurs due to specimen contact with
the sensor and allows the specimen to heat to a temperature during the test the same as that which might occur
in an actual fire exposure. This mounting condition gives a measure of the insulation performance and thermal
capacity of the specimen and air gap as a combination.
NOTE 7 The contact configuration, with the sensor in contact with the specimen, gives a measure of the
insulation performance and thermal capacity of the specimen and reflects applications in which the textile is in
contact with the protected surface.
vi © ISO 2019 – All rights reserved

---------------------- Page: 6 ----------------------
INTERNATIONAL STANDARD ISO 17492:2019(E)
Clothing for protection against heat and flame —
Determination of heat transmission on exposure to both
flame and radiant heat
1 Scope
This document specifies a test method for measuring the heat transferred through horizontally
mounted flame-resistant textile materials when exposed to a combination of convective and radiant
heat. The exposure conditions are adjusted to be approximately a 50/50 mixture of pure convective
2
heat and pure radiant heat. The total exposure heat flux is 84 kW/m .
This test method is applicable to any type of sheet material used either as a single layer or in a multilayer
construction when all structures or sub-assemblies are made of flame-resistant materials. It does not
apply to materials that are not flame resistant.
This test method does not apply to the evaluation of materials exposed to any other type of thermal
energy sources, such as radiant heat only or flame contact only. ISO 6942 is applicable when evaluating
materials for exposure to radiant heat only. ISO 9151 is applicable when evaluating materials due to
flame contact only.
NOTE Some, but not all, textiles materials can ignite and continue to burn after exposure to the convective
and radiant heat produced by this test method.
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 139, Textiles — Standard atmospheres for conditioning and testing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
break-open
formation of a hole in the material during thermal exposure
3.2
burn injury
burn damage that occurs at various levels of depth within human tissue
Note 1 to entry: Burn injury in human tissue occurs when the tissue is heated and kept at an elevated temperature
for a critical period of time. The amount of burn injury (first, second or third degree) depends upon both the level
of the elevated temperature and the duration. The material performance in this document is related to a second-
degree burn injury and is determined by the amount of thermal energy transferred through the specimen that is
sufficient to cause the onset of a second-degree burn. The onset of a second-degree burn injury involves damage
to the epidermis and part of the dermis.
© ISO 2019 – All rights reserved 1

---------------------- Page: 7 ----------------------
ISO 17492:2019(E)

3.3
charring
formation of carbonaceous residue as the result of pyrolysis or incomplete combustion
3.4
dripping
material response shown by the flow of the material and formation of falling droplets
3.5
embrittlement
formation of a brittle residue as the result of pyrolysis or incomplete combustion
3.6
exposure energy
thermal energy that is incident to the test specimen
3.7
exposure time
total time over which the exposure energy (3.6) is applied to the test material
3.8
heat flux
thermal intensity indicated by the amount of energy transmitted divided by time and by area to the
surface
2
Note 1 to entry: Heat flux is expressed in kilowatts per square metre (kW/m ).
3.9
heat transfer index (dual exposure)
HTI(DE)
time, in whole seconds, to cause a temperature rise of the copper calorimeter by 12 °C and 24 °C from a
combined convective and radiant heat exposure
Note 1 to entry: The time to cause a 12 °C temperature rise is indicated with a suffix of T12, and that for a 24 °C
rise with a suffix of T24, e.g. HTI(DE)-T12 and HTI(DE)-T24. The relative value between these two indices
indicates the characteristic of the energy transfer. If HTI(DE)-T24 is twice that of HTI(DE)-T12, the rate of
energy transfer is constant. If HTI(DE)-T24 is less than twice that of HTI(DE)-T12, the rate of energy transfer is
increasing, showing a loss in insulation performance. If HTI(DE)-T24 is greater than twice that of HTI(DE)-T12,
the rate of energy transfer is decreasing, showing increasing insulation performance.
3.10
heat transfer burn intersection
time, in seconds, at which the thermal energy transferred through the material and absorbed by the
copper calorimeter intersects the Stoll curve (3.18) where a second-degree burn injury is predicted
to begin
3.11
heat transfer burn time
time from the start of the thermal exposure to heat transfer burn intersection (3.10)
Note 1 to entry: Heat transfer is determined from the measured temperature rise of a sensor. In this test method,
a copper calorimeter is used as the sensor. The calorimeter diameter is large enough to average the heat received
through the exposed specimen. The calorimeter thickness is selected so as to cause the temperature rise of the
sensor to be similar to that of human tissue when exposed to heat. The sensor face is painted a dull black to cause
it to absorb radiant heat similarly to human tissue.
2 © ISO 2019 – All rights reserved

---------------------- Page: 8 ----------------------
ISO 17492:2019(E)

3.12
human tissue heat tolerance
amount of thermal energy transferred to human tissue that predicts a reaction in human tissue, such as
a pain sensation or the onset of a second-degree burn
[4]
Note 1 to entry: The tolerance of human tissue to heat exposure was developed by Stoll et al. (see Table 1) and
is referred to as the Stoll curve (3.18). It is used in this method as the heat transfer criteria in determining the
thermal protection index (TPI) (3.19) value of the test material.
3.13
ignition
initiation of combustion
3.14
melting
liquefaction of a material when exposed to heat
3.15
response to heat exposure
observable response of the textile to the exposure energy (3.6) as indicated by break-open (3.1), melting
(3.14), dripping (3.4), charring (3.3), embrittlement (3.5), shrinkage (3.16), sticking (3.17) or ignition (3.13)
3.16
shrinkage
decrease in one or more dimensions of an object or material
3.17
sticking
response evidenced by softening of a material and adherence of one material to the surface of itself or
another material
3.18
Stoll curve
relationship between the amount of thermal energy absorbed by human tissue and the time of exposure
which predicts the onset of a second-degree burn in human tissue
Note 1 to entry: See Table 1.
3.19
thermal protection index
TPI
total exposure energy (3.6) experienced by the specimen to cause a second-degree burn injury (3.2) to
begin which is defined by the time the measured temperature of the copper calorimeter intercepts the
Stoll curve (3.18)
2
Note 1 to entry: The exposure energy is expressed as energy per unit area in kJ/m .
4 Principle
A flame-resistant specimen, mounted in a static horizontal position, is placed a specific distance from a
2
combined convective/radiant heat source and exposed to a heat flux of (84 ± 2) kW/m until sufficient
thermal energy passes through the specimen to cause the equivalent of the onset of a second-degree
burn injury in human tissue, or to indicate a temperature rise of 24 °C in the copper calorimeter.
The specimen is mounted either in direct contact with the copper calorimeter, designated as the
“contact configuration”, or with a (6,35 ± 0,05) mm air space between the specimen and the copper
calorimeter, designated as the “spaced configuration”.
The test exposure is composed of convective energy supplied by two gas burners and radiant heat from
nine radiant tubes. The combined total energy of the exposure is achieved by first setting the radiant
exposure and then adding the convective source. The total energy exposure is then confirmed with the
© ISO 2019 – All rights reserved 3

---------------------- Page: 9 ----------------------
ISO 17492:2019(E)

copper calorimeter. Note that the gas burner flames contribute both convective and radiant heat to the
surface of the specimen.
The amount of energy transferred through and by the specimen is measured with a copper calorimeter
and analysed by one of the following two methods.
a) The thermal performance can be evaluated from the times for a 12 °C and 24 °C temperature
rise in the copper calorimeter: the HTI(DE)-T12 and HTI(DE)-T24 values. The rate at which
the temperature of the copper calorimeter rises is a direct measurement of the thermal energy
transferred.
b) The thermal performance can also be compared with the times for the energy transferred through
and by the specimen to cause the onset of a second-degree burn: the TPI. This index is based on the
[4]
human tissue heat tolerance data of Stoll et al .
The effect of the exposure on the physical appearance of the specimen shall be noted as specified in 10.4.
5 Apparatus
5.1 Heat source, consisting of a convective heat source and a radiant heat source. The convective
heat source shall consist of two Meker or Fisher burners affixed beneath the specimen holder assembly
opening and subtended at an angle between 30° to 45° from the horizontal so that the flames converge
at a point immediately beneath the specimen. The radiant heat source shall consist of nine 500W quartz
T3 translucent (frosted) infrared lamps affixed beneath and centred between the burners as shown in
Figure 1. The burners shall be Meker or Fisher burners with a 40 mm diameter top and with an orifice
size appropriate for propane gas.
NOTE Two different energy sources are used in this test method. The energy from the Meker burners is
primarily convective due to the flowing high temperature gases. These gases do emit thermal radiation. About
[5]
1/3 of the energy from the burners is in this form . The lamps are primarily radiant heaters but, because of
their location below the test specimen, convection currents will rise and strike the test specimen. The fraction of
the energy from the lamps that is convection is small.
3
5.2 Specimen holder assembly, consisting of a steel frame (7 850 ± 200) kg/m that rigidly holds
and positions, in a reproducible manner, the specimen support holder plate and specimen relative to the
heat source.
5.3 Protective shutter, placed between the heat source and the specimen. The protective shutter shall
be capable of completely dissipating the thermal load from the heat source (usually by means of water
cooling) for the time period before and after each specimen exposure. A microswitch shall be connected
to the shutter or manually operated to indicate the start of the exposure to the data acquisition system.
The start of exposure (i.e. time zero) shall be when the following edge clears the heat source.
3
5.4 Specimen mounting plate, consisting of a piece of steel (7 850 ± 200) kg/m , 200 mm square and
3,2 mm thick, with a 100 mm square hole in its centre. A piece of 90° angle section steel (6,35 mm by
25 mm long) shall be welded to the outside edge of each corner perpendicular to the plane of the plate.
The overall dimension, including the angle sections, will be about (212,7 ± 1) mm (see Figure 2).
3
5.5 Specimen holding plate, 200 mm × 200 mm × 3,2 mm thick steel (7 850 ± 200) kg/m with a
130 mm × 130 mm centred square hole. The spacer and sensor assembly shall fit without binding into
the hole of the specimen holding plate (see Figures 1 and 2).
3
5.6 Spacer, 130 mm × 130 mm × (6,35 ± 0,05) mm thick steel (7 850 ± 200) kg/m with a
100 mm × 100 mm centred square hole (see Figures 1 and 2).
4 © ISO 2019 – All rights reserved

---------------------- Page: 10 ----------------------
ISO 17492:2019(E)

5.7 Sensor assembly, a copper calorimeter assembled in a mounting block with an addit
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.