IEC 60695-11-11:2021

IEC 60695-11-11 ®
Edition 1.0 2021-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Fire hazard testing –
Part 11-11: Test flames – Determination of the characteristic heat flux for ignition
from a non-contacting flame source

Essais relatifs aux risques du feu –
Partie 11-11: Flammes d’essai – Détermination de la densité de flux de chaleur
caractéristique pour l'allumage à partir d'une flamme source sans contact

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IEC 60695-11-11 ®
Edition 1.0 2021-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ

Fire hazard testing –
Part 11-11: Test flames – Determination of the characteristic heat flux for

ignition from a non-contacting flame source

Essais relatifs aux risques du feu –

Partie 11-11: Flammes d’essai – Détermination de la densité de flux de chaleur

caractéristique pour l'allumage à partir d'une flamme source sans contact

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.40; 29.020 ISBN 978-2-8322-1045-9

– 2 – IEC 60695-11-11:2021 © IEC 2021
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Principle of the test . 9
5 Apparatus . 9
5.1 Test arrangement . 9
5.2 Burner and test flame . 11
5.3 Heat flux meter . 11
5.4 Data acquisition system . 11
5.5 Heat flux meter mounting board . 11
5.6 Masking board . 12
5.7 Timing device . 12
5.8 Conditioning chamber . 12
5.9 Test specimen support . 12
5.10 Burner support . 12
5.11 Observation mirror . 13
5.12 Flow controller . 13
5.13 Heat flux meter supporting device . 13
6 Test specimen . 13
6.1 Dimensions of test specimen . 13
6.2 Testing ranges in formulations . 14
6.2.1 General . 14
6.2.2 Density, melt flows and filler/reinforcement . 14
6.2.3 Colour . 14
6.3 Conditioning of test specimens . 14
7 Testing conditions . 14
8 Test procedure . 14
8.1 Determination of incident heat flux calibration curve . 14
8.2 Determination of ignition time. 15
8.3 Repetition of the test at different heat flux values . 16
9 Evaluation of test results . 16
9.1 Average ignition time . 16
t
ig
9.2 Report format for CHFI . 16
9.3 Analysis on CHFI (optional) . 17

10 Precision data . 17
11 Test report . 17
Annex A (informative) An example of the calibration curve of incident heat flux, Q,
versus the distance, D, between the top of the burner tube and the lower surface of the
test specimen . 18
A.1 Calibration curve . 18
Annex B (informative) Examples of ignition times with various materials of 3 mm
thickness . 20
B.1 Materials – Examples of measurements . 20
Annex C (informative) Precision data . 23

C.1 General . 23
C.2 Heat flux versus distance at different gas flow rates . 23
C.3 Repeatability . 24
C.4 Calculations and plots . 25
Annex D (informative) Method of positioning the heat flux meter . 28
D.1 General . 28
D.2 Positioning the heat flux meter . 28
Bibliography . 30

Figure 1 – Arrangement and position of test specimen and burner . 10
Figure 2 – Heat flux meter mounting board . 11
Figure 3 – Structure of the masking board . 12
Figure 4 – Heat flux meter supporting device . 13
Figure A.1 – Calibration curve (example) . 18
Figure B.1 – Example of ignition times of PMMA . 20
Figure B.2 – Ignition times for ABS (example) . 21
Figure B.3 – Ignition times for HIPS (example) . 21
Figure C.1 – Incident heat flux calibration curve (gas flow rate 105 cm /min) . 23
Figure C.2 – Incident heat flux calibration curve (gas flow rate 160 cm /min) . 24
Figure C.3 – Plot of 1/ t for material A . 26
ig
Figure C.4 – Plot of 1/t for material B . 26
ig
Figure C.5 – Plot of 1/ t for material C . 27
ig
Figure C.6 – Plot of 1/ t for material D . 27
ig
Figure D.1 – Positioning the heat flux meter . 28
Figure D.2 – Correct position of the test specimen support and the heat flux meter. 29

Table A.1 – Calibration data (examples of actual measured data as shown
in Figure A.1) . 19
Table A.2 – Calibration data (examples of interpolated values) . 19
Table B.1 – Value of Figure B.1 . 20
Table B.2 – Value of Figure B.2 . 21
Table B.3 – Value of Figure B.3 . 22
Table B.4 – Description example of tabulated test results . 22
Table C.1 – Precision data of ignition time . 25

– 4 – IEC 60695-11-11:2021 © IEC 2021
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 11-11: Test flames –
Determination of the characteristic heat flux
for ignition from a non-contacting flame source

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC 60695-11-11 has been prepared by IEC technical committee 89: Fire hazard testing.
It has the status of a basic safety publication in accordance with IEC Guide 104 and
ISO/IEC Guide 51.
The text of this International Standard is based on the following documents:
CDV Report on voting
89/1482/CDV 89/1507/RVC
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
This international standard is to be used in conjunction with IEC 60695-11-4.
A list of all the parts in the IEC 60695 series, under the general title Fire hazard testing, can be
found on the IEC website.
Part 11 consists of the following parts:
Part 11-2: Test flames – 1 kW nominal pre-mixed flame – Apparatus, confirmatory test
arrangement and guidance
Part 11-3: Test flames – 500 W flames – Apparatus and confirmational test methods
Part 11-4: Test flames – 50 W flame – Apparatus and confirmational test method
Part 11-5: Test flames – Needle-flame test method – Apparatus, confirmatory test
arrangement and guidance
Part 11-10: Test flames – 50 W horizontal and vertical flame test methods
Part 11-11: Test flames – Determination of the characteristic heat flux for ignition from non-
contacting flame source
Part 11-20: Test flames – 500 W flame test methods
Part 11-30: Test flames – History and development from 1979 to 1999
Part 11-40: Test flames – Confirmatory tests – Guidance
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

– 6 – IEC 60695-11-11:2021 © IEC 2021
INTRODUCTION
In the design of any electrotechnical product, the risk of fire and the potential hazards
associated with fire need to be considered. In this respect the objective of component, circuit
and equipment design as well as the choice of materials is to reduce, to acceptable levels, the
potential risks of fire even in the event of foreseeable abnormal use, malfunction or failure.
IEC 60695-1-10, IEC 60695-1-11 and IEC 60695-1-12 provide guidance on how this is to be
accomplished.
Fires involving electrotechnical products can be initiated from external non-electrical sources.
Considerations of this nature are dealt with in an overall fire hazard assessment.
The aim of the IEC 60695 series of standards is to save lives and property by reducing the
number of fires or reducing the consequences of the fire. This can be accomplished by
– trying to prevent ignition caused by an electrically energised component part and, in the
event of ignition, to confine any resulting fire within the bounds of the enclosure of the
electrotechnical product.
– trying to minimise flame spread beyond the product’s enclosure and to minimise the harmful
effects of fire effluents including heat, smoke and toxic or corrosive combustion products.
This international standard is to be used to measure and describe the properties of materials
used for electrotechnical products and sub-assemblies in response to heat from a non-
contacting flame source or heat source under controlled laboratory conditions which is
characterized by quantitative heat input (heat flux) to the materials. Results of this test may be
used as elements of a fire risk assessment which takes into account all of the factors which are
pertinent to an assessment of the fire hazard of a particular end use. A test specimen cut from
an end-product or sub-assembly can be tested by this test method.
This international standard may involve hazardous materials, operations, and equipment. It
does not purport to address all of the safety problems associated with its use. It is the
responsibility of the user to establish appropriate safety and health practices and determine the
applicability of regulatory limitations prior to use.
Test methods to determine flammability by contact of flame have been developed and
standardized already, such as IEC 60695-11-5 [1] , IEC 60695-11-10 [2], IEC 60695-11-20 [3]
and ISO 4589-2 [4].
This is the first test method to determine the characteristic heat flux for ignition (CHFI) of
materials used for electrotechnical products, sub-assemblies or parts from a non-contacting
flame source. CHFI characterizes ignition behaviour in terms of incident heat flux. This test
method simulates the fire behaviour of materials used for electrotechnical products where a
flame source or heat source exists close to, but does not contact with, these items. An example
is a candle flame near an electrotechnical product.

__________
Numbers in square brackets refer to the bibliography.

FIRE HAZARD TESTING –
Part 11-11: Test flames –
Determination of the characteristic heat flux
for ignition from a non-contacting flame source

1 Scope
This part of IEC 60695 describes a test method used to determine the characteristic heat flux
for ignition (CHFI) from a non-contacting flame source for materials used in electrotechnical
products, sub-assemblies or their parts. It provides a relationship between ignition time and
incident heat flux. A test specimen cut from an end-product or sub-assembly can be tested by
this test method.
This part of IEC 60695 can be used in the fire hazard assessment and fire safety engineering
procedures described in IEC 60695-1-10, IEC 60695-1-11 and IEC 60695-1-12.
This basic safety publication is intended for use by technical committees in the preparation of
standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51.
One of the responsibilities of a technical committee is, wherever applicable, to make use of
basic safety publications in the preparation of its publications. The requirements, test methods
or test conditions of this basic safety publication will not apply unless specifically referred to or
included in the relevant publications.
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.
IEC 60695-1-10, Fire hazard testing – Part 1-10: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines
IEC 60695-1-11, Fire hazard testing – Part 1-11: Guidance for assessing the fire hazard of
electrotechnical products – Fire hazard assessment
IEC 60695-1-12, Fire hazard testing – Part 1-12: Guidance for assessing the fire hazard of
electrotechnical products – Fire safety engineering
IEC 60695-4, Fire hazard testing – Part 4: Terminology concerning fire tests for electrotechnical
products
IEC 60695-11-4, Fire hazard testing – Part 11-4: Test flames – 50 W flame – Apparatus and
confirmational test method
IEC GUIDE 104, The preparation of safety publications and the use of basic safety publications
and group safety publications
ISO/IEC Guide 51, Safety aspects – Guidelines for their inclusion in standards

– 8 – IEC 60695-11-11:2021 © IEC 2021
ISO 13943:2017, Fire safety – Vocabulary
ISO 291, Plastics – Standard atmospheres for conditioning and testing
ISO/TS 14934-4, Fire tests – Calibration of heat flux meters – Part 4: Guidance on the use of
heat flux meters in fire tests
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13943:2017 and
IEC 60695-4, some of which are reproduced below for the user’s convenience, as well as the
following apply.
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
3.1
average ignition time, t
ig
arithmetic mean of three ignition times measured at a given heat flux
3.2
characteristic heat flux for ignition
CHFI
maximum incident heat flux which is a multiple of 5 kW/m and at which t is greater than 120 s
ig
3.3
draught-free environment
space in which the results of experiments are not significantly affected by the local air speed
Note 1 to entry: A quantitative 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
[SOURCE ISO 13943:2017, 3.83]
3.4
heat flux
amount of thermal energy emitted, transmitted or received per unit area and per unit of time
Note 1 to entry: the typical unit is W/m
[SOURCE ISO 13943:2017, 3.201]
3.5
ignition
initiation of combustion which results in a sustained flaming combustion for at least 5 s
Note 1 to entry: The term “ignition” in French has a very different meaning [state of body combustion].
3.6
incident heat flux
heat flux received by the surface of a test specimen
[SOURCE: ISO 13943:2017, 3.226]

4 Principle of the test
The incident heat flux, Q, is measured using the apparatus described in 5.3 and 5.4. The
incident heat flux is controlled by the distance, D, between the top of the burner tube and the
lower surface of the test specimen and by the flow rate of fuel gas to the burner (See Annex A).
The time required to ignite the test specimen is measured as a function of the incident heat flux.
The tests are performed at different levels of incident heat flux until the maximum heat flux, at
which the average ignition time is greater than 120 s, is obtained. This maximum heat flux
t
ig
is defined as the characteristic heat flux for ignition (CHFI). The incident heat flux values at
2 2
which the tests are carried out are chosen within the range of 30 kW/m to 75 kW/m and shall
be integral multiples of 5 kW/m .

5 Apparatus
5.1 Test arrangement
The arrangement of the apparatus and the position of the test specimen and burner are shown
in Figure 1. The test specimen and masking board shall be mounted horizontally. The burner
tube shall be mounted vertically. The centre of the test specimen, the burner tube, the sensor
of the heat flux meter and the conical hole in the masking board shall all be aligned vertically.
The sensor of the heat flux meter shall be placed horizontally 6 mm above the upper surface of
the masking board with its sensing surface facing down, i.e. the sensing surface of the heat flux
meter is placed in the horizontal plane where the lower surface of the test specimen is placed.

– 10 – IEC 60695-11-11:2021 © IEC 2021
Dimensions in millimetres
Key
1 Test specimen
2 Test specimen support
3 Masking board
4 Conical hole (diameter at the top side 15 mm)
5 Burner tube and test flame (inner diameter 9,5 mm)
6 Burner support (adjustable vertically)
7 Mirror
D Distance between the top of the burner tube and the lower surface of the test specimen
Figure 1 – Arrangement and position of test specimen and burner

5.2 Burner and test flame
The burner shall conform to IEC 60695-11-4. The flame size and the gas flow rate will differ
from that specified in IEC 60695-11-4 in order to obtain the heat flux necessary for the test. The
test flame used for each test shall be kept unchanged throughout the test. The fuel gas shall
be methane gas having a purity of 98 % or greater.
5.3 Heat flux meter
The heat flux meter shall be of a water-cooled thermopile type (see ISO/TS 14934-4) which
determines the incident heat flux, Q, applied to the test specimen.
When incident heat flux measurements are made, the heat flux meter shall be placed in the
centre of a heat flux meter mounting board, and the heat flux meter shall not have any optical
filter in-line with the sensor.
NOTE 1 The incident heat flux measurement is of critical importance to the test results. ISO 14934-3 [5] provides
the calibration method for the heat flux meter.
NOTE 2 A heat flux meter of Schmidt-Boelter type with a thermopile, which has a measurement range of up to
100 kW/m and a target diameter of approximately 12,5 mm, has been found to be suitable for the purpose of this
international standard.
5.4 Data acquisition system
The voltmeter for measuring the output of the heat flux meter shall have a resolution of 0,01 %
or better for the maximum output range.
NOTE The usual output level of the heat flux meter is several tens of millivolts.
5.5 Heat flux meter mounting board
The heat flux meter mounting board shall be approximately 75 mm × 75 mm × 12 mm with a
centrally located hole whose diameter is slightly larger than the outside diameter of the heat
flux meter. The board shall be made from a heat-resistant non-combustible rigid board. The
heat flux meter mounting board is used, together with the heat flux meter (see Figure 2), for the
determination of incident heat flux, Q (see 8.1).
NOTE A calcium silicate board of approximately 12 mm thickness having a dry density of approximately
(850 ± 50) kg/m has been found suitable for the heat flux meter mounting board.

Key
1 Heat flux meter mounting board
2 Heat flux meter
3 Cooling water pipe
a Approximately 12 mm
b Approximately 75 mm
Figure 2 – Heat flux meter mounting board

– 12 – IEC 60695-11-11:2021 © IEC 2021
5.6 Masking board
The masking board shall consist of three heat-resistant non-combustible rigid boards, each
having a dry density of (850 ± 50) kg/m and a thickness of (8 ± 0,5) mm. The total thickness
of the three non-combustible boards shall be (24 ± 1,5) mm. One board is inserted between the
upper and lower boards and shall be made moveable. This moveable board works as a radiant
heat shield which protects the test specimen from the heat source before the commencement
of the test. There shall be a conically shaped opening at the centre of the masking board. The
diameter of the opening on the upper surface shall be (15 ± 1) mm and (57 ± 1) mm on the
lower surface. An illustration of the masking board and its operation is shown in Figure 3.
-1 -1
NOTE A calcium silicate board of the required density has a thermal conductivity of 0,14 W⋅m ⋅K at 200 °C,
-1 -1 -1 -1
0,15 W⋅m ⋅K at 400 °C, and 0,17 W⋅m ⋅K at 600 °C.

Key
1 Masking board
2 Upper board
3 Moveable board (Radiant heat shield)
4 Lower board
a Position of the moveable masking board prior to a test
b Position of the moveable masking board during a test
Figure 3 – Structure of the masking board
5.7 Timing device
The timing device shall have a resolution of 0,5 s or better.
5.8 Conditioning chamber
The conditioning chamber shall have a capability of maintaining the temperature at (23 ± 2) ºC,
and the relative humidity within (50 ± 10) % (see ISO 291).
5.9 Test specimen support
The test specimen support shall maintain a distance of (6 ± 0,5) mm between the lower surface
of the test specimen and the upper surface of the masking board.
5.10 Burner support
The burner shall be located on a support which can adjust the position of the burner in the
vertical direction. The distance, D, between the top of the burner tube and the lower surface of
the test specimen shall be determined using a suitable measuring device which has a resolution
of 1 mm or better.
5.11 Observation mirror
To observe the ignition behaviour of the test specimen, an observation mirror approximately
100 mm × 100 mm shall be positioned underneath the masking board (See Figure 1).
5.12 Flow controller
The fuel gas flow controller shall have a control range of between 100 ml/min and 200 ml/min,
and have a resolution of 5 ml/min or better.
5.13 Heat flux meter supporting device
In order to correctly place the heat flux meter at the measurement position, the heat flux meter
supporting device as shown in Figure 4 shall be used.
Dimensions in millimetres
Figure 4 – Heat flux meter supporting device
6 Test specimen
6.1 Dimensions of test specimen
The test specimen shall be a flat plate. Each test specimen shall be at least (77,5 ± 2,5) mm in
length and width and at the thickness under consideration. The preferred thicknesses for the
presentation of comparative data include (0,4 ± 0,05) mm, (0,75 ± 0,1) mm, (1,5 ± 0,1) mm,
(3,0 ± 0,2) mm and (6,0 ± 0,4) mm.

– 14 – IEC 60695-11-11:2021 © IEC 2021
6.2 Testing ranges in formulations
6.2.1 General
The results of tests carried out on test specimen sets of different colour, thickness, density,
molecular mass, anisotropic type/direction, additives, fillers, and/or reinforcements can vary.
6.2.2 Density, melt flows and filler/reinforcement
Test specimens covering all combinations of minimum and maximum levels of density, melt
flows and filler/reinforcement content may be provided and considered representative of the
range if the test results yield the same CHFI. If the test results do not yield the same CHFI for
all test specimens representing the range, evaluation shall be limited to the materials with the
specific levels of density, melt flows and filler/reinforcement tested. In addition, test specimens
with intermediate density, melt flows, and filler/reinforcement content shall be tested to
determine the representative range for each CHFI determination. However, as an alternative,
the least favorable performance of the specific levels of density, melt flows and
filler/reinforcement tested may be considered representative of intermediate levels without
additional testing.
6.2.3 Colour
When evaluating a range of colours, uncoloured test specimens and test specimens with the
highest level of organic and inorganic pigment loading by weight are considered representative
of the colour range if the test results yield the same CHFI. When certain pigments are known
to affect flammability characteristics, the test specimens containing those pigments shall also
be tested. Test specimens which shall be tested are those that
a) contain no colouring,
b) contain the highest level of organic pigments,
c) contain the highest level of inorganic pigments,
d) contain pigments which are known to adversely affect flammability characteristics.
6.3 Conditioning of test specimens
Unless otherwise specified in the relevant specification, the test specimen shall be conditioned
for a minimum of 24 h at (23 ± 2) ºC and at a relative humidity of (50 ± 10) %. Once removed
from the conditioning chamber, the test specimens shall be tested within 1 h.
7 Testing conditions
All test specimens shall be tested in a laboratory atmosphere in a draught free environment at
a temperature of between 15 °C and 35 °C and at a relative humidity of 75 % or less.
8 Test procedure
8.1 Determination of incident heat flux calibration curve
The incident heat flux, Q, which will be received by the surface of the test specimen, shall be
determined in terms of the distance, D, between the top of the burner and the lower surface of
the test specimen and the flow rate of the fuel gas supplied to the burner. For this purpose, an
incident heat flux calibration curve shall be determined by the following procedures.
a) Install the heat flux meter into a heat flux meter mounting board as shown in Figure 2.
b) Place the heat flux meter, which is placed in the centre of the heat flux meter mounting
board, in the test specimen position. The detailed method of placing the heat flux meter is
described in Annex D.
c) Place the burner (see 5.2) in position.

d) Measure the distance, d, between the top of the burner tube and the lower surface of the
masking board. The distance, D, between the top of the burner tube and the sensing surface
of the heat flux meter is determined by
D = d + 6 + thickness of the masking board in millimeter.
e) Place the radiation heat shield in the shielding position (see Figure 3, position a).
f) Turn on the fuel gas supply to the burner and ignite the gas. Adjust the flow rate.
2 2 3
NOTE For heat fluxes in the range 30 kW/m to 60 kW/m , a fuel gas flow of 105 cm /min has been found to be
2 2 3
suitable. For heat fluxes in the range 55 kW/m to 75 kW/m , a fuel gas flow of 160 cm /min has been found to be
suitable.
g) Wait for a period of at least 5 min to allow the burner to reach the equilibrium condition.
h) The radiant heat shield shall then be removed (see Figure 3, position b), and the output of
the heat flux meter shall be recorded for 2 min.
i) Perform this measurement at several different distances (D) between the sensing surface
of the heat flux meter and the top of the burner tube, so as to obtain a relationship of the
2 2
incident heat flux in the range of 30 kW/m to 75 kW/m and the distance, D, between the
sensing surface of the heat flux meter and the top of the burner.
j) Plot a calibration curve of incident heat flux, Q, as a function of the distance, D, and obtain,
2 2
by interpolation, the distances which correspond to the heat fluxes of 30 kW/m , 35 kW/m ,
2 2 2 2 2 2 2 2
40 kW/m , 45 kW/m , 50 kW/m , 55 kW/m , 60 kW/m , 65 kW/m , 70 kW/m , and 75 kW/m
(see Annex A).
The temperature of cooling water for the heat flux meter shall be maintained above the ambient
temperature in order to avoid water condensation on the sensing surface (see ISO/TS 14934‑4).
8.2 Determination of ignition time
The test shall be conducted under a selected incident heat flux value, in terms of the distance,
D, between the top of the burner and the lower surface of the test specimen and the gas flow
rate to the burner, obtained in accordance with 8.1.
For the purposes of this test method, ignition is defined in 3.5.
a) Adjust the distance between the top of the burner and the lower surface of the test specimen
and adjust the gas flow rate to the burner in order to obtain the selected incident heat flux
value.
b) Ignite the burner and control the fuel gas flow rate. Wait for a period of at least 5 min to
allow the burner conditions to reach equilibrium.
c) Place the radiation heat shield in the closed position (see Figure 3, position a).
d) Place the test specimen in the test specimen position (see Figure 1).
e) Pull aside the radiant heat shield to the open position (see Figure 3, position b) and
simultaneously start the timing device.
f) Observe the test specimen and note if phenomena such as deformation, cracking and
melting occur.
g) If the test specimen ignites within 120 s, observe the flaming combustion for at least 5 s,
record the time to ignition ( t ) and return the radiation shield to the closed position (see
ig
Figure 3, position a). The test can be stopped if sustained and continuous combustion has
been observed for at least 5 s.
h) If the test specimen does not ignite within 120 s, record the failure to ignite, and return the

radiation shield to the closed position (see Figure 3, position a).
i) Repeat d) to h) above two more times with a new test specimen each time and under the
same test conditions.
j) Calculate and record t , the arithmetic mean of the three ignition times.
ig
– 16 – IEC 60695-11-11:2021 © IEC 2021
If a dripping occurs before igniting, the test is invalid. This is because drips will affect the burner
and change the nature of the flame.
8.3 Repetition of the test at different heat flux values
2 2
The incident heat flux shall be chosen within the range from 30 kW/m to 75 kW/m and shall
be an integral multiple of 5 kW/m .
The tests shall be carried out until the highest incident heat flux value at which t is greater
ig
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