ISO/TS 5660-3:2012

TECHNICAL ISO/TS
SPECIFICATION 5660-3
First edition
2012-12-01
Reaction-to-fire tests — Heat release,
smoke production and mass loss rate —
Part 3:
Guidance on measurement
Essais de réaction au feu — Débit calorifique, taux de dégagement de
fumée et taux de perte de masse —
Partie 3: Lignes directrices relatives au mesurage
Reference number
©
ISO 2012
© ISO 2012
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ii © ISO 2012 – All rights reserved

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Capability and limitations of the cone calorimeter . 1
4 Calibration of the cone calorimeter . 2
4.1 General . 2
4.2 Heat flux meter calibration (see 6.12 and 10.3.1 of ISO 5660-1:2002) . 2
4.3 Calibration frequency . 2
4.4 Oxygen analyser calibration (see 10.1.5, 10.1.6 and 10.2.3 of ISO 5660-1:2002) . 3
4.5 Determining orifice plate calibration factor . 4
4.6 Additional comments on the orifice calibration factor . 4
4.7 Calibration of smoke measurement system . 5
4.8 Precautions in relation to water/CO removal . 6
4.9 Routine maintenance . 6
5 Test specimen preparation and presentation .6
5.1 General . 6
5.2 Specimen trays and edge retainer frame . 8
6 Selection of heat flux .9
7 Ignition protocols .11
8 Guidance on the testing of non-standard products .11
8.1 General .11
8.2 Non-planar products .11
8.3 Radiation transfer considerations .13
8.4 Thermally mobile specimens.19
9 Composites and layered products .20
9.1 General .20
9.2 Non-homogeneous products.20
9.3 Specimens with short test duration .20
10 Liquids .21
10.1 General .21
10.2 Testing without the radiant heater .21
10.3 Testing with the radiant heater .22
11 The theory of oxygen consumption calorimetry .22
11.1 General .22
11.2 Silicones .23
11.3 Effect of additives and fillers .24
12 Start and end of test .25
12.1 Start of test .25
12.2 End of test .25
13 Recommendations for presentation of data .25
13.1 Current situation .25
13.2 Additional useful data .26
13.3 Recommendations .29
Annex A (informative) Predictive methods from ISO 5660-1 data .30
Annex B (informative) Effect of additives and fillers .37
Annex C (informative) Measurements at low levels of heat release .40
Bibliography .42
iv © ISO 2012 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International
Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies
casting a vote.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of document:
— an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical
experts in an ISO working group and is accepted for publication if it is approved by more than 50 %
of the members of the parent committee casting a vote;
— an ISO Technical Specification (ISO/TS) represents an agreement between the members of a
technical committee and is accepted for publication if it is approved by 2/3 of the members of the
committee casting a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for
a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or
ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be
transformed into an International Standard or be withdrawn.
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.
ISO/TS 5660-3 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 1, Fire
initiation and growth.
This first edition of ISO/TS 5660-3 cancels and replaces ISO/TR 5660-3:2003.
ISO 5660 consists of the following parts, under the general title Reaction to fire tests — Heat release,
smoke production and mass loss rate:
— Part 1: Heat release rate (cone calorimeter method)
— Part 2: Smoke production rate (dynamic measurement)
— Part 3: Guidance on measurement [Technical Specification]
Introduction
The first edition of ISO 5660-1, which describes a test method for rate of heat release from building
products by means of a cone calorimeter, was published in 1993, following approximately 10 years of
development within ISO/TC 92, Fire safety, Subcommittee SC 1, Fire initiation and growth.
The cone calorimeter is a fire test instrument in which horizontal specimens are exposed to controlled
levels of radiant heating by means of a truncated cone-shaped heater. Continuous spark ignition is
provided and the time to ignition is recorded for specimens which ignite. The rate of heat release from
the burning specimen is determined from measurements of the amount of oxygen consumed from the
air flowing through the apparatus, which has been demonstrated to equate to heat release. The mass of
the specimen is also measured throughout the burning period. The specimens are usually tested under
well ventilated conditions.
Results are expressed in terms of peak and average rates of heat release, as well as total heat released
and the effective net heat of combustion. ISO 5660-1:2002 limits the specimen type to essentially flat.
Several other groups are now utilizing the cone calorimeter, and a number of new parameters in addition
to those defined in ISO 5660-1:2002 and ISO 5660-2:2002 have been defined and used. Some of these,
including smoke measurement, require that measurements be made from the beginning of the test rather
than at the onset of ignition, which is commonly used as the starting point for heat release measurement.
The cone calorimeter is also designed to allow measurement of smoke and gases such as CO and CO .
Smoke measurement is the subject of ISO 5660-2:2002. Further work is under way to define a quality
control tool for measuring burning rates of building products. ISO 17554 specifies a test apparatus
similar to that of ISO 5660-1:2002 but measures only loss of mass when exposed to radiant heat. Mass
loss may be a surrogate for measurement of heat release for some classes of building materials. A similar
system which measures the temperature of combustion products generated by this apparatus has been
[23]
standardized as ISO 13927 . The cone calorimeter fire model is used to measure corrosivity of gases
[24]
products of combustion in ISO 11907-4 . The effect of the evolved gases on the resistance of a printed
circuit board target is used to assess corrosivity.
During development of the cone calorimeter it became apparent that there was considerable interest
in the use of the instrument for products other than building products. Several standards have been
developed by various national and international groups based on ISO 5660-1:2002 and ISO 5660-2:2002.
This part of ISO 5660 provides recommendations for the testing of products in the cone calorimeter
and gives guidance on application of the test results. Supplementary guidance is given in documents
referred to in References [1] and [2].
vi © ISO 2012 – All rights reserved

TECHNICAL SPECIFICATION ISO/TS 5660-3:2012(E)
Reaction-to-fire tests — Heat release, smoke production
and mass loss rate —
Part 3:
Guidance on measurement
1 Scope
This part of ISO 5660 examines the measurement limitations and applications of the cone calorimeter
data as currently used for building products, and recommends ways in which some of these may be
overcome for other types of products for other application areas. It compiles information from a large
body of experience with regard to the use of the instrument. This information is presented as a set of
guidelines, which will help to standardize the use of the cone calorimeter in this wider scope.
Particular guidance is given on aspects of specimen preparation and on the behaviour, such as melting,
spalling and intumescing, of specimens exposed to radiant heat. The relevance of specimen thickness
and the use of substrate, and methods of fixing to substrate, are also discussed. Advice is given on
approaches to testing a variety of “non-standard” products. Recommendations are made on techniques
of calibration of the apparatus, selection of appropriate heat flux levels and ignition protocols.
2 Normative references
The following referenced documents are indispensable for the application 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 5660-1:2002, Reaction-to-fire tests — Heat release, smoke production and mass loss rate — Part 1:
Heat release rate (cone calorimeter method)
ISO 5660-2:2002, Reaction-to-fire tests — Heat release, smoke production and mass loss rate — Part 2:
Smoke production rate (dynamic measurement)
ISO/TS 14934-4:2007 Fire tests — Calibration of heat flux meters — Part 4: Guidance on the use of heat
flux meters in fire tests
3 Capability and limitations of the cone calorimeter
Rate of heat release is one of the fundamental properties of fire and should almost always be taken into
account in any assessment of fire hazard. Heat release significantly affects fire growth. Considerable progress
has been made in methods of using rate of heat release and ignition time results from the cone calorimeter
to predict full scale fire characteristics. These characteristics include time to flashover in a small room lined
with the tested product and exposed to a high energy fire source such as that used in ISO 9705.
The design of the instrument also provides for measurement of smoke (both gravimetrically and
optically) and other gaseous products of pyrolysis or combustion. The instrument may thus be applied
to the assessment of real fire hazards such as smoke and toxic and corrosive gas emission in addition
to heat release, particularly when the results are expressed in terms of fundamental physically based
parameters, rather than ad hoc parameters.
When functioning as a rate of heat release apparatus, the parameter which is measured in the exhaust
from the specimen is the concentration of oxygen. Temperature measurements are made, but these are
not used to measure the heat output from the specimen in the manner of a conventional calorimeter.
This is a crucial point in understanding heat release by oxygen consumption calorimetry. The theory of
oxygen consumption calorimetry is discussed in more detail in Clause 10.
The instrument is limited to bench scale specimens and it uses a simple fire model which provides
continuous free ventilation and removal of the products of combustion. Specimen behaviour during
the experiment such as shrinking and swelling can be tolerated if this happens within small margins,
but if the specimen intumesces so that it touches the igniter or the cone, or if it exhibits spalling, this
behaviour will invalidate the results generated.
4 Calibration of the cone calorimeter
4.1 General
Regular and accurate calibration of several measuring devices is essential in order for valid results
to be obtained from the cone calorimeter. The following calibration procedures are outlined in
ISO 5660-1:2002, Clause 10 (respectively 10.1 to 10.3):
— preliminary calibration;
— operating calibration;
— less frequent calibrations.
Table 1 gives details of the major calibration requirements together with recommended intervals.
Calibration procedures are to some extent controlled by the apparatus and the comments below may not
apply to all makes of cone calorimeter.
Some guidelines are given on actual operating experiences with these calibrations and follow the clause
headings given in ISO 5660-1:2002. In addition there are some additional comments on low orifice
calibration factors and the cause thereof. The clause numbers in parentheses refer to clauses given in
ISO 5660-1:2002.
4.2 Heat flux meter calibration (see 6.12 and 10.3.1 of ISO 5660-1:2002)
Detailed information on heat flux meter calibration is provided in ISO/TS 14934-4:2007.
Great care should be taken of the heat flux meter which is in regular use and care should be taken to
use this always with water cooling. It should be checked regularly against a primary meter as set out in
Annex E of ISO 5660-1:2002, to ensure its continued correct working.
4.3 Calibration frequency
The setting of the required heat flux is set out in the manuals of the various instruments. Once a steady-
state value has been obtained (fluctuations of ± 0,1°C may occur) this value should be noted for future
reference and act as an early warning of some change. In particular, users should ensure that the control
thermocouples which should be situated behind and touching the heater helix (i.e. the face remote from
the specimen) do not penetrate the heater helix and experience the temperature of the flame rather than
that of the heater winding.
Table 1 provides information on the frequency of calibration of the instrumentation for the operation of
the Cone Calorimeter.
2 © ISO 2012 – All rights reserved

Table 1 — Frequency for calibration and maintenance procedures
a
Equipment item Prior to run Daily Monthly Occasional
Check that unused
Drying/CO
portion is suffi- — — —
removal columns
b
cient
Analyser flow rates
Oxygen analyser Span Pressure/zero —
time offsets
Check and replace
Main filter — — —
if needed
Soot mass filter Place in position — — Controller set up
Check loading tare
Load cell Calibrate — —
and mass
Heat flux/tempera-
ture relationship
c
Irradiance Check temperature Heat flux level —
Heat flux meter
against reference
meter
CO/CO — Zero/span — —
Heat release flow
rates of 5 kW and
Heat release flow
methane burner
Methane — rate of 5 kW for —
methane burner
Mass flow control-
ler
Check adjustment
Laser smoke pho- Check response Check photometer
and 100 % trans- —
tometer with filter zero
mission
Differential pres-
— Check zero — Check calibration
sure transducer
PMMA burn — — — Perform test
a
These calibrations need only be carried out very occasionally or when alterations have been made to the system.
b
Always before spanning the oxygen analyser.
c
Also when required to change irradiance level.
4.4 Oxygen analyser calibration (see 10.1.5, 10.1.6 and 10.2.3 of ISO 5660-1:2002)
Few problems should be encountered when carrying out the calibration of the oxygen analyser. When
running the “zero” check using pure nitrogen with analysers equipped to measure pressure in the sensor
cell, it has been found easier to set the nitrogen flow using the analyser pressure reading. The nitrogen
flow is adjusted until the pressure reading is the same as when the analyser is fed from the atmosphere.
The oxygen analyser delay time should be determined from time to time (recommended frequency, once
every three months) as set out in 10.1.5 of ISO 5660-1:2002. It should be remembered that because of the
time offset, the amount of valid data collected would be lower than the total test time by the extent of
the delay time. Thus, start to record the oxygen analyser output at the same time the calibration burner
is placed underneath the exhaust hood and continue until 3 min after removal of the calibration burner.
4.5 Determining orifice plate calibration factor
4.5.1 Calibration using methane (see 10.2.4 of ISO 5660-1:2002)
It is recommended that the calibration consisting of burning methane be carried out when the heater
has been set at the required heat flux. This allows the differential pressure transducer (DPT) to warm
up. The fan is shut down and the DPT re-adjusted to zero. The fan is then set to the required air flow and
then the burning of methane is carried out.
ISO 5660-1:2002 requires that at the start of each day, one heat release calibration corresponding to a
heat release flow rate of 5 kW of the supplied methane be carried out. An orifice constant between 0,040
and 0,046 should be obtained with 99,9 % or 99,5 % methane at a flow rate of 8,37 l/min at 273 K (0°C)
and 1 atm (101,3 Pa)). Daily calibration factors should agree within approximately ±1 %.
It should be noted that the heat release calibration using methane does not constitute an absolute
calibration of the instrument, but rather that it verifies the orifice plate constant, which appears in the
calculations [see Equation (5) in 12.2, Equation (7) in 12.3.2 and Equation (9) in 12.4 of ISO 5660-1:2002].
It is not a direct measurement of heat release.
Black polymethylmethacrylate (PMMA) (with a thickness of 6 mm or greater) can also be used within
each laboratory to check repeatability of the cone calorimeter performance.
When zeroing the differential pressure transducer (DPT), ensure that the duct fan and any “decoupled”
extractor system are switched off. Air should be prevented from flowing over the open end of the stack
and across the orifice plate. If necessary, a plastic bag or equivalent should be used to block the open end
of the stack.
It is important to keep records of the values of X (oxygen analyser reading, mole fraction of oxygen),
O2
T (absolute temperature of gas at the orifice meter) and Δp (orifice meter pressure differential) which
e
lead to good calibration factors which should also be noted every time the calibration is carried out. In
this way any discrepancy is immediately identified and early correction can be carried out.
4.5.2 Calibration using liquids
It should be noted that when calibrating using liquids, which usually have low flash points, it is essential
that calibrations be performed on a cold system (the cone heater is not powered). The liquid should be
held in a stable vessel, and the vessel should be stable under the cone before ignition of the liquid. The
burning liquid should not be disturbed until it is all burned.
In addition to burning methane for calibration, users have used a variety of materials such as alcohols.
The heats of combustion of ethanol and propan-2-ol are 26,8 kJ/g and 30,2 kJ/g, respectively. It is
desirable to use propan-2-ol with a purity ≥ 99,5 %.
4.6 Additional comments on the orifice calibration factor
Some variation of the orifice plate calibration factor (also known as the methane calibration factor) may
be observed for various reasons. However, any change greater than 5 % is indicative of a malfunction. In
the majority of cases, the problem is caused by leaks into the sampling lines, in which case the recorded
factor will be higher than usual. Other items that can cause problems are
— blockages in the gas sampling line,
— connections between the orifice plate and the differential pressure transducer,
— leaks at the methane supply line,
— faulty differential pressure transducer,
— faulty methane flow meter,
— cold-trap refrigeration system clogged,
4 © ISO 2012 – All rights reserved

— inactive CO removal agent. (If CO is not removed from the gas stream entering the oxygen analyser,
2 2
the heat release determined using the standard equations will be higher than expected; hence the
calibration factor will be lower.)
4.7 Calibration of smoke measurement system
Calibration using filters assumes that the system used to calibrate the filter is superior to the optical
system in the cone calorimeter. The photodiodes used in the cone calorimeter specify a high degree
of linearity. The optical density quoted for a commercially supplied filter is usually the average over a
range of wavelengths and the value at the frequency of the monochromatic laser used in the cone may
not be this average value. Therefore, the use of the filter is better confined for daily routine checking of
the proper functioning of the system rather than as a primary calibration.
The user may therefore calibrate by checking zero and 100 % values and utilizing the linearity of
the photodiode.
If filters calibrated at the correct wavelength are used, the following routine may be used. The smoke
measurement system should be checked weekly using neutral density glass filters of 0,3 nominal optical
density. This procedure assumes that the smoke system is the conventional split beam laser described
in ISO 5660-2.
Place the filter in the beam between the duct and the detector. Collect data for a period of 60 s. The
measured calibration extinction coefficient, k , is obtained from the equation:
mc
k = ln(I /I)/d
mc 0
where d is the duct diameter.
The correct k value, k , is given by the equation:
c
k = 2,303D′/d
c
where D′ is the optical density of the calibration filter.
A correction factor, f, is calculated from these two k values and is used to correct all subsequent
measured k values.
f = k /k
c mc
thus
k′ = k f
m
where
k′ is the corrected value;
k is the measured value.
m
Where a calibration factor, F, is used, it is calculated as follows:
F = f/d
and subsequent k′ values are calculated using the equation:
k′ = ln(I /I) × F
The filter used should be of the doped type because coated filters can give rise to interference effects
with laser light and can deteriorate with time. The filter should have a reliable calibration covering the
wavelength of the measurement. The light transition factors of the filters should be checked every three
years as the factor may change in use over several years.
4.8 Precautions in relation to water/CO removal
Where carbon monoxide and carbon dioxide are analysed in the gas stream it is important to select the
correct drying agent. Some drying agents (e.g. silica gel) lead to tailing of the carbon dioxide peaks due
to absorption on the drying agent. Anhydrous calcium sulfate has been found to be the most reliable
drying agent and is recommended when carbon dioxide is to be analysed.
4.9 Routine maintenance
It should be noted that all safety precautions regarding potentially toxic or carcinogenic dusts should
be carefully observed when cleaning the ductwork and traps. Particular precautions should be taken
when dealing with fluorinated or other compounds with high toxic potencies. The study of fluorine-
containing compounds needs to be conducted with care as the generation of hydrogen fluoride can
result in chemical attack on the glass beads of the refrigeration column as well as on human tissue due
to the highly corrosive nature of this compound.
The equipment will always collect a certain amount of soot. Some will inevitably be deposited on the
inside of the ductwork. This should be removed regularly by brushing and vacuum cleaning.
The gas sampling probe and the associated tubing, which connect to the oxygen analyser, require periodic
cleaning. One indication of blocking is the need to adjust the waste regulator repeatedly to maintain the
proper flow to the oxygen analyser. Cleaning of the interconnecting tubes consists of disassembling the
various sections of tubing and blowing them through with compressed air [0,70 MPa (100 psi)].
Never direct high pressure air into the analyser and remember to vent the dirt and soot to a safe place.
The pump situated in the gas sampling train should be cleaned or serviced following the manufacturer’s
instructions.
5 Test specimen preparation and presentation
5.1 General
Specimen preparation is described in Clause 8 of ISO 5660-1:2002 and the advice given therein is
generally recommended. Products used at thicknesses between 6 mm and 50 mm should be tested at
the finished thickness. For products thicker than 50 mm the advice in 8.1.4 and 8.1.5 of ISO 5660-1:2002
recommends that the product is cut down to 50 mm from the unexposed face. Care should be taken
when reducing the total thickness to ensure that the resulting product is representative of the original
specimen. Products used at thicknesses thinner than 6 mm should be tested at the finished thickness
as in end-use or fixed to a typical substrate. Guidance on the selection and use of suitable substrates is
given in ISO/TR 14697. Systems using air gaps should be studied carefully since this can influence the
results and special protocols should be determined. Figure 1 shows that the same piece of material can
give very different results when tested:
a) flat without an air gap;
6 © ISO 2012 – All rights reserved

b) with an air gap that allows the specimen to burn on both sides;
c) with an air gap that allows pyrolysis products to escape from the irradiation zone unburnt.
In all cases, it is important that specimen construction enable pyrolysis products that are generated
behind surface layers to be vented from composite specimens in a similar way to that which they would
be released in the burning end product. Combustion products can either be vented from the top of the
specimen holder where the flames are and contribute to the heat release or may be vented from the base
of the specimen holder. Pyrolysis products escaping around the base of the specimen holder may also
burn but this is not necessarily the case.
It is possible that the upper part of the specimen may have been completely combusted and that during
the latter stages of the test, the only combustion may be due to pyrolysis from the inside of the specimen
escaping around the specimen edge.
In other circumstances, pyrolysis can take place so rapidly that the combustion concentration limit is
exceeded before the pyrolysis fumes ignite. The use of the specimen shield (6.2 of ISO 5660-1:2002)
or positioning the igniter before the test may be of assistance. It is important that specifiers and users
ensure that the data are relevant and consistent in testing sets of products (see also 8.4 and 11.3).
Y
0 100 200 300
X
a) Composite over mineral fibre pad
Y
0 100 200 300
X
b) Composite over air gap (two-sided burning)
Y
0 100 200 300
X
c) Composite over air gap (one-sided burning)
Key
X time (s)
Y heat release rate (kW/m )
Figure 1 — Rate of heat release against time curves for 3 mm thick polyester resin/woven glass
roving composites tested at 50 kW/m
5.2 Specimen trays and edge retainer frame
The 25 mm metal trays and associated retainer frames used for testing should be constructed from
stainless steel as specified in ISO 5660-1:2002. Use of incorrect steel may mean that there is a large mass
range for the trays that would then have differing thermal inertia and lead to variation in test results.
ISO 5660-1:2002 requires that an edge retainer frame be used when testing in the horizontal orientation.
For composite products, edge coverage is important to be consistent with the end use application and
reduce any edge burning effects. However, some industry sectors may find that the use of the edge
8 © ISO 2012 – All rights reserved

[4]
retainer frame is unnecessary for their applications. Babrauskas has studied this extensively. This
may be the case where low heat release rates from low thermal inertia materials are being masked
[5]
because of the high thermal capacity of comparatively bulky specimen hardware. The CBUF study
examined furniture composites without using any edge frames. The CBUF test recommendations were
[30]
accepted by the ASTM committee E5 in 1995 when it replaced the 1993 protocol in ASTM E1474 .
If an edge retainer frame is used, the surface area will be less than the 0,01 m . The exposed area should
be clearly stated in the reports.
6 Selection of heat flux
ISO 5660-1:2002 does not prescribe the level of irradiance to be used in testing. It is the responsibility
of the end user or the product committees to ensure that the recommended heat flux levels selected
are appropriate to end use. This will require careful consideration of the available research data on the
application. In general, two approaches are available:
— testing at a heat flux deemed to be that of the design fire;
— measuring the burning properties at a heat flux at which the material readily ignites.
Most measurements will be required for post-ignition test conditions and the user should first decide if
that is the case, as most properties measured will be very different depending on whether ignition has or
has not occurred. When the intention is to assess post-ignition properties of the product, it is important
to test at a heat flux which causes ignition to occur within, at most, about 10 min. This is because at lower
heat fluxes specimens may show irreproducible ignition behaviour. In circumstances where materials
show variable performance because they have been tested close to their critical ignition fluxes, it is
recommended to consider testing at least 5 kW/m above this irradiance to obtain more reliable data
concerning the intrinsic performance of the material.
2 2 2 2
It is recommended to select levels from 25 kW/m , 35 kW/m , 50 kW/m and 75 kW/m . These levels
are not special but are useful levels within the operating range of the cone calorimeter (10 kW/m to
100 kW/m ), and they are suggested in order that users produce data at a limited number of heat flux
levels rather than at a wide number of arbitrary heat flux levels within the operating range.
Users will have the following objectives for results from the cone calorimeter:
a) to generate fundamental bulk material properties;
b) to generate input data into fire engineering models;
c) to predict performances in larger scale tests;
d) to develop specifications which require the use of the cone calorimeter.
Users with objectives a) are likely to need to map the properties of materials over a range of heat flux
levels. For exploratory testing it is suggested that irradiances of 35 kW/m be used. Further information
2 2
can be found for materials that resist ignition at 35 kW/m by retesting at 50 kW/m , and for those
2 2
which readily ignite at 35 kW/m by retesting at 25 kW/m . To obtain bulk material properties it is
important to test thick specimens and to analyse data during the period when the material is behaving
as a thermally thick specimen. In practice, this means testing specimens that are at least 6 mm thick but
preferably 10 mm thick, and analysing data obtained over a period of a few minutes starting about 1 min
after ignition.
Users with objectives b) will generally be guided by the requirements of the models to be used.
Users with objectives c) will be making their decisions from recent research results, as this is a developing
area. Predictions can be based on statistical correlations or the use of mathematical models. In both
cases, it is important to match the level of heat received by the specimen in the cone calorimeter to that
to be received by the majority of the specimen in the larger scale assessment.
Examples are as follows:
— If a material supplier is interested in assessing the possible application of a material for sheathing
on an electric cable, indication of its performance in an IEC 60332-3-10 test could be gained from
2 [31] 2
testing it at 50 kW/m . Testing at 75 kW/m would be required in order to assess the likelihood
[33]
of the same material surviving the UL 910 test required for US plenum cables.
— Many upholstered furniture composites will ignite and burn in a repeatable manner when tested at
2 [33]
a heat flux of 25 kW/m (defined in NFPA 264A ) but the more ignition-resistant composites may
not, and the higher heat flux of 35 kW/m (specified in ASTM E1474) may be necessary.
Users with objectives d) have similar requirements to those with objectives c). This group should note
that the simplest types of specification would require the selection of a “design” irradiance to which
materials will be exposed. There will generally be materials that will ignite under the irradiance and
those that will not. It need not necessarily be a requirement of the specification that the material
showing “good” reaction (i.e. little reaction) to the radiation be tested at a higher irradiation to give good
repeatability, provided that the specification is written so as to foresee any possible variability with such
materials. Generally comparisons between materials for ranking or pass/fail-based test specifications
would need to be made on common irradiance tests, but it is important to specify the relevant heat flux
values since the relative rankings of materials can change at different heat flux values.
Table 2 gives some indication of the ranges of irradiances developed in some typical fires or fire test
environments. Refer to the actual reference to find details of the position of the heat flux measurement.
Table 2 — Ranges of irradiance developed in some typical fires or fire test environments
Irradiance Ref. Examples of effects
kW/m
12 to 22 [7] Critical ignition flux of many materials, e.g. polyethylene, polyacetal,
PMMA, wood, hardboard
10 to 40 [8] Output from waste paper basket fires
18 to 20 [9] Match flames
20 to 25 [13] Heat flux at floor level in flashover fire with ceiling temperature > 600 °C
20 to 40 [10] Developing fire with 10 % to 15 % O by volume
< 25 [10] Oxidative pyrolysis fire 5 % to 21 % O by volume
25 [12] Flux below vertical spreading wall flame
25 to 45 [12] Flux on wall from vertical wall burning
30 to 40 [9] Small (up to 250 mm high) gas diffusion flames
40 to 70 [10] Low ventilation fully developed fire 1 % to 5 % O by volume
40 to 115 [12] On facade 0,8 m to 3,3 m above window at lintel
60 to 120 [7] Premixed gas burner
50 to 150 [10] High ventilation fully developed room fire 5 % to 10 % O by volume
70 to 150 [12] Average ceiling values for post-flashover room fire
90 to 200 [12] Average wall values for post-flashover room fire
105 to 175 [12] Peak ceiling values for post-flashover room fires
115 to 230 ]12] Peak wall values in post-flashover room fires
120 to 145 [12] Peak floor values in post-flashover room fires
85 to 105 [7] Kerosene blow lamp
140 [7] Premixed blow torches oxyacetylene
200 [12] Fully developed fire > 10 MW
10 © ISO 2012 – All rights reserved

Table 2 (continued)
Irradiance Ref. Examples of effects
kW/m
200 [11] Jet fire average
300 [11] Jet fire peak
7 Ignition protocols
For all cone testing, it is important that a correct ignition time be recorded. In certain circumstances,
for example furniture testing, the ignition time can be very short, i.e. less than 5 s. If this ignition point
is missed, the concentration of pyrolysis products can become too high to allow the spark igniter system
used in the cone to actually ignite the volatiles.
One method to ensure that the correct ignition time is recorded is to select a sufficiently low heat flux so
as to give a longer ignition time. However, lowering the heat flux can cause other
...