ISO/TS 19850:2022
(Main)Fire tests — Use of LED (light-emitting diode) as an alternative to white light for measuring smoke parameters
Fire tests — Use of LED (light-emitting diode) as an alternative to white light for measuring smoke parameters
This document specifies methodologies for comparing the smoke density and the smoke production rate during fire tests measured by LED (light-emitting diode) with those measured by white light. These methodologies are intended for the identification of suitable LEDs which can be used as alternatives to white light sources.
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TECHNICAL ISO/TS
SPECIFICATION 19850
First edition
2022-05
Fire tests — Use of LED (light-emitting
diode) as an alternative to white light
for measuring smoke parameters
Reference number
ISO/TS 19850:2022(E)
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ISO/TS 19850:2022(E)
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ISO/TS 19850:2022(E)
Contents Page
Foreword .v
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units. 1
5 Principle . 2
6 Overview of smoke measurement used in existing light extinction test methods .2
6.1 General . 2
6.2 Light-receiving system . 3
6.3 Measuring device . 3
6.4 Neutral density filter comparison . 3
7 LED light sources .3
8 Comparison of spectra from different light sources . 3
9 Method of measurement in each apparatus where the white light system is
originally installed .4
9.1 General . 4
9.2 Comparison between the original white light and the new LED in ISO 9705-1 . 5
9.2.1 General . 5
9.2.2 Method A . . . 6
9.2.3 Method B . . 7
9.3 Comparison between the original white light and the new LED in ISO 24473 . 7
9.4 Comparison between the original white light and the new LED in ISO 9239-1 . 7
9.4.1 General . 7
9.4.2 Method B . . 8
9.5 Comparison between the original white light source and the new LED source in
EN 13823 . . . 9
9.5.1 General . 9
9.5.2 Method A . . . 9
9.5.3 Method B . 10
9.6 Comparison between the original white light source and the new LED source in
IEC 61034-1 . 10
9.6.1 General . 10
9.6.2 Method B . . 11
10 Test fire sources .12
10.1 General .12
10.2 For standard tests in which a burner is used .12
10.3 For standard tests in which radiant heat is used .12
10.4 For standard tests in which liquid fuel is used .12
10.5 For the standard tests in which the fire source is not prescribed .13
11 Alternative method .13
11.1 General .13
11.2 Overview of apparatus .13
11.3 Smoke generator . 14
11.4 Flexible hose . 15
11.5 Exhaust fan . 15
11.6 Duct . . 15
11.7 Light source system .15
11.8 Test environment . 15
11.9 Test procedure for static system . 15
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12 Comparing the experimental results from the original white light and the
candidate LED .16
12.1 General . 16
12.2 Calculation method — transmission . 16
Annex A (informative) Example of measurements in the IEC 61034-1:2005 apparatus .17
Bibliography .19
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ISO/TS 19850:2022(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 92, Fire safety, Subcommittee SC 1, Fire
initiation and growth.
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.
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ISO/TS 19850:2022(E)
Introduction
Traditional white light bulbs including tungsten incandescent lamps, used until now for smoke density
measurements in fire tests, are no longer available. Methods therefore need to be developed for their
replacement with LED (light-emitting diode) light sources. This document is intended to provide
guidance on replacing the light source in a smoke density measurement with an LED light source.
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TECHNICAL SPECIFICATION ISO/TS 19850:2022(E)
Fire tests — Use of LED (light-emitting diode) as an
alternative to white light for measuring smoke parameters
1 Scope
This document specifies methodologies for comparing the smoke density and the smoke production
rate during fire tests measured by LED (light-emitting diode) with those measured by white light. These
methodologies are intended for the identification of suitable LEDs which can be used as alternatives to
white light sources.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
opacity of smoke
ratio of incident light intensity to transmitted light intensity through smoke, under specified conditions
3.2
optical density of smoke
measure of the attenuation of a light beam passing through smoke expressed as the logarithm to the
base 10 of the opacity of smoke
3.3
transmittance
ratio of transmitted light intensity through smoke to incident light intensity, under specified conditions
3.4
smoke
visible part of fire effluent
3.5
smoke production
amount of smoke that is produced in a fire or fire test
3.6
smoke production rate
amount of smoke produced per unit of time in a fire or fire test
4 Symbols and units
For the purposes of this document, the symbols and units shown in Table 1 apply.
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ISO/TS 19850:2022(E)
Table 1 — Symbols and their designations and units
Symbol Definition Unit
D degree of freedom 1
d optical density 1
I light transmission at time, t 1
j j
I measurement of light transmission for LED 1
LED
I measurement of light transmission for white light 1
WH
N normal distribution 1
n sample size -
s relative spectral distribution of a LED light 1
LED
s relative spectral distribution of a white light 1
Lamp
t time at point x s
x
t critical point (time) s
crit
V variance 1
d
Δp pressure difference on the measurement section Pa
λ wavelength nm
σ standard deviation 1
5 Principle
White light systems are currently used in several documents, for example, ISO 9239-1, ISO 9705-1,
ISO 24473, IEC 61034-1, EN 13823 and EN 50399.
This document explains how the abovementioned standards can be amended based on the following
comparisons in order to confirm that a given replacement light source is suitable:
1) comparison of light source spectra, as described in Clause 8;
2) comparison of apparatus (ISO 9705-1, ISO 24473, ISO 9239-1and EN 13823), as described in
Clause 9;
NOTE There are two different methods described in Clause 9: method A (which is the preferred method) and
method B.
3) comparison in an alternative experimental set-up specially designed for this purpose, as described
in Clause 11.
6 Overview of smoke measurement used in existing light extinction test
methods
6.1 General
The white light smoke measurement system used in ISO 9239-1, ISO 9705-1 and ISO 24473, for example,
consists of a light-emitting system and a receiver with a lens system in between. All parts are described
in ISO 3182 and to some extent in each of the mentioned standards.
The light source is a gas-filled tungsten incandescent lamp. There are some small differences in colour
temperature between the different apparatuses. A lens system is fitted to make a (nearly) parallel light
beam with a diameter of 20 mm or 25 mm.
The detector has a spectral responsivity agreeing with the CIE photopic curve. It can be a silicon photo
2
diode at least 7 mm with a spectral filter set in front for adjusting the responsivity to fit the CIE
photopic curve.
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ISO/TS 19850:2022(E)
The receiver system is the same as prescribed in ISO 9239-1, for example.
6.2 Light-receiving system
All the light-receiving systems conform to ISO 3182, regardless of light source bulb in the light source
system.
The light-receiving system shall consist of an achromatic system of lenses and a silicon photo-electric
diode in front of which a spectral filter is located to accommodate the human eye luminosity function
on viewing in daylight (Figure A.1).
6.3 Measuring device
The measuring device conforms to ISO 3182.
The measuring device is fitted with an amplifier that can be tuned to display the voltage of the photo-
electric diode as a percentage of the initial value (transmission). The accuracy of the display is within
±1,5 % of the final value. There is a means for outputting the measured values for external recording.
In order to simplify evaluation of the measurements, the instrument may have a logarithmic output to
allow the optical density to be recorded externally.
6.4 Neutral density filter comparison
The calibration procedure conforms to EN 50399.
The following steps are performed with the measuring equipment operating.
a) Place a light-blocking insert into the filter holder and adjust to 0.
b) Remove the light-blocking insert and adjust the signal from the light receiver to 100 %.
c) Start the time measurement and record the signal from the light receiver for a period of two
minutes.
d) Introduce one of the following filters and record the corresponding signal for at least one minute
where the filters to be used are with optical density, d, 0,04 - 0,1 - 0,3 - 0,5 - 0,8 - 1,0 and 2,0.
e) Repeat step d) for the other filters.
f) Stop the data acquisition and calculate the mean transmission values for all filters.
Each d-value calculated from the mean transmission value [d = - lg(l)] should be within ±5 % or ±0,01 of
the theoretical d-value of the filter, whichever is the greater.
7 LED light sources
LED sources that are considered as replacement candidates for the white light system should provide
a continuous light spectra. The illumination reaching the detector side should be powerful enough to
have a similar signal output as measured with the white light source (i.e. the strength of the light from
the LED falling on the detector is similar to the white light). The light source shall be stable within
±0,5 % including temperature, for short- and long-term duration. The power source shall be adapted to
ensure this.
8 Comparison of spectra from different light sources
Various LEDs exist with different colour and spectral distributions. Considering the purpose of light
attenuation for smoke density measurement, it is necessary to understand the spectral distribution of
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ISO/TS 19850:2022(E)
the tested LED. Figure 1 shows an example of spectral distribution of an LED (white) compared with
that of white light.
Key
X spectra (nm) white light
Y light intensity (-) white LED
Figure 1 — Example of spectral distribution of white light and LED (white)
If the spectrum of the LED light is known as exemplified in Figure 1 then the potential for the LED
evaluated can be determined by comparing the spectra of the LED and the old white light system
over the range of wavelengths (320 ~ 1 100 nm) to which the detector is sensitive. The comparison is
conducted by multiplying the spectra with the sensitivity curve of the detector and then integrating
over the wavelength range, as shown in Formulae (1) and (2):
1 100
sd× λ (1)
LED
∫
320
1 100
sd× λ (2)
Lamp
∫
320
The difference in the integral shall be less than 5 %, as expressed in Formula (3):
1 100 1100 11 100
||sd×× λ - sd λ / sd×< λ ,005 (3)
LEDLampLamp
∫∫ ∫
320 320 320
For example, in case of Figure 1, compared to the integral value of white light as standard, the integral
value of white LED is 2,89 % less.
9 Method of measurement in each apparatus where the white light system is
originally installed
9.1 General
In this clause, the method of comparing the transmission values of both the original white light and
the new light source (LED) is described in relation to each standardized test method. As the smoke
production rate and the smoke density are calculated based on the transmission values, the comparison
procedures in this clause are primarily focused only on the light transmission.
There are two methods for installing the new light source (LED) to the duct: method A (the preferred
method) and method B. In method A, both the new light source (LED) and the receiver are installed in
the proximity of the original white light system. The advantage of this method of installing the new
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light source (LED) is that it is possible to measure the transmission of two different light systems at the
same time with the same smoke. On the other hand, the disadvantage is that it is necessary to make this
new arrangement in the duct.
In method A the additional system should be placed a defined distance away from the original white
light system. The distance shall be sufficient for avoiding any influence on the original white light
system. A distance of one duct diameter is generally sufficient. This needs to be checked by turning
on only one of the lights to see if it reaches the other detector. However, it is important to ensure that
the additional system does not influence the flow profile or the measurements of the other parameters
such as flow measurement and gas analysis. The additional system should also not be too close to bends
in the duct or subject to other flow profile changes.
In method B, the original light source (white light) is replaced by the new light source (LED). The
advantage of this method is that it is not necessary to make a new arrangement in the duct. On the other
hand, the disadvantage is that it is impossible to measure the transmission of the two light systems
at the same time. It is possible to remove this disadvantage by using repeatable test fire sources on
each occasion. This means that the repeatability of smoke generation should be carefully considered in
method B. Therefore, it is recommended to use method A wherever possible. If the situation does not
always permit the additional installation of a new light source in the duct because of restrictions in the
apparatus or laboratory environment, etc., then method B can be used as an alternative. In the case of
ISO 9239-1, it is only possible to use method B.
Information on suitable test fire sources is given in Clause 10, and according to that information, three
or more kinds of fire sources should be used for each test apparatus. For method A, two tests are
performed with each fire source (six tests in total), while for method B, three tests are performed with
each fire source and with each light source, resulting in eighteen tests in total.
9.2 Comparison between the original white light and the new LED in ISO 9705-1
9.2.1 General
In this example, both method A and method B could be applied. The exhaust system of ISO 9705-1 is
shown in Figure 2.
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ISO/TS 19850:2022(E)
Dimensions in millimetres
Key
A-A section of exhaust duct
1 guide vanes 8 frame of steel profile (50 mm × 100 mm × 3,2 mm)
2 pitot tube 9 steel plates (1 000 mm × 3 000 mm)
3 guide vanes 10 steel plates (2 mm × 500 mm × 900 mm)
4 lamp, photocell system 11 hood (2 mm-thick steel plates)
5 gas analysis 12 four steel plates (395 mm × 400 mm)
a
6 exhaust duct (Ø 400 mm) To exhaust gas cleaning.
7 opening (3 000 mm × 3 000 mm)
Figure 2 — Exhaust system of ISO 9705-1
9.2.2 Method A
9.2.2.1 Installation of both the new light source (LED) and the receiver
Both the new light source (LED) and the receiver are installed in the proximity of the original white
light system, which consists of the light source and the receiver. Both the new light source (LED) and
the receiver should be located at a distance of one duct diameter from the position of original white
light system. Both the LED and white light system need to be downstream of the gas analysis point.
9.2.2.2 Measurement of transmission of both the original white light and the new LED
The test fire source is burned under the hood for the ISO 9705-1 system, and transmission is measured
for both the original white light system and the new LED system, at the same time (method A).
The position of the two light sources is exchanged, but the receivers are not moved, and the measurement
is conducted again.
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The comparison of the experimental results from the different light sources is conducted according to
Clause 12.
9.2.3 Method B
9.2.3.1 Measurement of transmission of the original white light
The test fire source is burned under the hood for the ISO 9705-1 system, and transmission of the original
white light system is measured.
9.2.3.2 Replacing the original light source (white light) by the new light source (LED)
The original light source (white light) is replaced by the new light source (LED). The receiver remains
in place.
9.2.3.3 Measurement of transmission of the new light source (LED)
The test fire source is burned under the hood for the ISO 9705-1 system, and transmission is measured
with the new light source (LED).
The comparison of the experimental results from the different light sources is conducted according to
Clause 12.
9.3 Comparison between the original white light and the new LED in ISO 24473
Regarding the measurement of smoke, ISO 24473 is technically almost identical to ISO 9705-1. Therefore,
the same procedure as in 9.2 is applied here. Only the test fire source can be different, because the fire
source is not fixed in ISO 24473. Information on the test fire source is found in Clause 10.
9.4 Comparison between the original white light and the new LED in ISO 9239-1
9.4.1 General
In this example, there is only one method that can be applied: method B. The exhaust system of
ISO 9239-1:2010 is shown in Figure 3.
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ISO/TS 19850:2022(E)
Key
1 lamp 7 pilot flames from line burner
2 exhaust duct 8 scale
3 detector 9 observation window
4 exhaust hood 10 specimen holder with specimen together on sliding platform
5 test chamber 11 air inlet all around specimen at bottom of chamber
6 gas-fired radiant panel
Figure 3 — Exhaust system of ISO 9239-1:2010
9.4.2 Method B
9.4.2.1 Measurement of transmission of the original white light system
The test fire source is burned, and transmission of the original white light system is measured.
9.4.2.2 Replacing the original light source (white light) by the new light source (LED)
The original light source (white light) is replaced by the new light source (LED). The receiver remains
in place.
9.4.2.3 Measurement of transmission of the new light source (LED)
The test fire source is burned, and transmission is measured with the new light source (LED).
The comparison of the experimental results from the different light sources is conducted according to
Clause 12.
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ISO/TS 19850:20
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