SIST EN IEC 60695-6-1:2021
(Main)Fire hazard testing - Part 6-1: Smoke obscuration - General guidance (IEC 60695-6-1:2021)
Fire hazard testing - Part 6-1: Smoke obscuration - General guidance (IEC 60695-6-1:2021)
This part of IEC 60695 gives guidance on:
a) the optical measurement of obscuration of smoke;
b) general aspects of optical smoke test methods;
c) consideration of test methods;
d) expression of smoke test data;
e) the relevance of optical smoke data to hazard assessment.
This basic safety publication focusing on safety guidance is primarily intended for use by
technical committees in the preparation of safety publications 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.
Prüfungen zur Beurteilung der Brandgefahr - Teil 6-1: Sichtminderung durch Racuh - Allgemeiner Leitfaden (IEC 60695-6-1:2021)
Essais relatifs aux risques du feu - Partie 6-1: Obscurcissement dû à la fumée - Recommandations générales (IEC 60695-6-1:2021)
IEC 60695-6-1:2021 est disponible sous forme de IEC 60695-6-1:2021 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.
L'IEC 60695-6-1 fournit des recommandations relatives:
a) au mesurage optique de l'obscurcissement de la lumière par la fumée;
b) aux aspects généraux des méthodes d’essais optiques de la fumée;
c) aux considérations concernant les méthodes d’essai;
d) à l’expression des résultats d’essais de fumée;
e) à la pertinence des résultats des mesurages optiques de la fumée pour l’évaluation du danger.
La présente publication fondamentale de sécurité portant sur des recommandations de sécurité est avant tout destinée à être utilisée par les comités d'études dans le cadre de l'élaboration de publications de sécurité, conformément aux principes établis dans le Guide 104 de l’IEC et dans le Guide ISO/IEC 51.
L'une des responsabilités d'un comité d'études consiste, le cas échéant, à utiliser les publications fondamentales de sécurité dans le cadre de l'élaboration de ses publications.
Cette troisième édition annule et remplace la deuxième édition de l’IEC 60695-6-1 parue en 2005 et l’Amendement 1:2010. Elle constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- Les références à l’IEC TS 60695-6-30 (annulée en 2016) ont été supprimées.
- Les références à l’IEC TS 60695-6-31 (annulée en 2016) ont été supprimées.
- Des références à l’ISO 5659-2 ont été ajoutées.
- Le domaine d’application contient du texte supplémentaire.
- Les termes et définitions ont été mis à jour.
- Le paragraphe 3.2 a été mis à jour.
- Le paragraphe 7.1 a été mis à jour.
Elle a le statut de publication fondamentale de sécurité, conformément au Guide IEC 104 et au Guide ISO/IEC 51. Cette Norme internationale doit être utilisée conjointement avec l’IEC 60695-6-2.
Preskušanje požarne ogroženosti - 6-1. del: Otemnitev dima - Splošna navodila (IEC 60695-6-1:2021)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 60695-6-1:2021
01-november-2021
Nadomešča:
SIST EN 60695-6-1:2005
SIST EN 60695-6-1:2005/A1:2010
Preskušanje požarne ogroženosti - 6-1. del: Otemnitev dima - Splošna navodila
(IEC 60695-6-1:2021)
Fire hazard testing - Part 6-1: Smoke obscuration - General guidance (IEC 60695-6-
1:2021)
Prüfungen zur Beurteilung der Brandgefahr - Teil 6-1: Sichtminderung durch Racuh -
Allgemeiner Leitfaden (IEC 60695-6-1:2021)
Essais relatifs aux risques du feu - Partie 6-1: Obscurcissement dû à la fumée -
Recommandations générales (IEC 60695-6-1:2021)
Ta slovenski standard je istoveten z: EN IEC 60695-6-1:2021
ICS:
13.220.40 Sposobnost vžiga in Ignitability and burning
obnašanje materialov in behaviour of materials and
proizvodov pri gorenju products
29.020 Elektrotehnika na splošno Electrical engineering in
general
SIST EN IEC 60695-6-1:2021 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 60695-6-1:2021
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SIST EN IEC 60695-6-1:2021
EUROPEAN STANDARD EN IEC 60695-6-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2021
ICS 13.220.99; 29.020 Supersedes EN 60695-6-1:2005 and all of its
amendments and corrigenda (if any)
English Version
Fire hazard testing - Part 6-1: Smoke obscuration - General
guidance
(IEC 60695-6-1:2021)
Essais relatifs aux risques du feu - Partie 6-1: Prüfungen zur Beurteilung der Brandgefahr - Teil 6-1:
Obscurcissement dû à la fumée - Recommandations Sichtminderung durch Racuh - Allgemeiner Leitfaden
générales (IEC 60695-6-1:2021)
(IEC 60695-6-1:2021)
This European Standard was approved by CENELEC on 2021-09-09. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 60695-6-1:2021 E
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EN IEC 60695-6-1:2021 (E)
European foreword
The text of document 89/1472/CDV, future edition 3 of IEC 60695-6-1, prepared by IEC/TC 89 “Fire
hazard testing” was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
EN IEC 60695-6-1:2021.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2022-06-09
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2024-09-09
document have to be withdrawn
This document supersedes EN 60695-6-1:2005 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 60695-6-1:2021 was approved by CENELEC as a
European Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards
indicated:
IEC 60695-1-12 NOTE Harmonized as EN IEC 60695-1-12
ISO 5659-2 NOTE Harmonized as EN ISO 5659-2
IEC 61034-1 NOTE Harmonized as EN 61034-1
IEC 61034-2 NOTE Harmonized as EN 61034-2
2
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SIST EN IEC 60695-6-1:2021
EN IEC 60695-6-1:2021 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the
relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60695-1-10 - Fire hazard testing - Part 1–10: Guidance EN 60695-1-10 -
for assessing the fire hazard of
electrotechnical products - General
guidelines
IEC 60695-1-11 - Fire hazard testing - Part 1–11: Guidance EN 60695-1-11 -
for assessing the fire hazard of
electrotechnical products - Fire hazard
assessment
IEC 60695-4 - Fire hazard testing - Part 4: Terminology EN IEC 60695-4 -
concerning fire tests for electrotechnical
products
IEC 60695-6-2 - Fire hazard testing - Part 6–2: Smoke EN IEC 60695-6-2 -
obscuration - Summary and relevance of
test methods
IEC Guide 104 - The preparation of safety publications and - -
the use of basic safety publications and
group safety publications
ISO 13943 2017 Fire safety - Vocabulary EN ISO 13943 2017
ISO/IEC Guide 51 - Safety aspects - Guidelines for their - -
inclusion in standards
3
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SIST EN IEC 60695-6-1:2021
IEC 60695-6-1
®
Edition 3.0 2021-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
HORIZONTAL PUBLICATION
PUBLICATION HORIZONTALE
Fire hazard testing –
Part 6-1: Smoke obscuration – General guidance
Essais relatifs aux risques du feu –
Partie 6-1: Obscurcissement dû à la fumée – Recommandations générales
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 13.220.99; 29.020 ISBN 978-2-8322-1004-7
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms, definitions and symbols . 8
3.1 Terms and definitions . 8
3.2 Symbols . 10
4 General aspects of smoke test methods . 11
4.1 Fire scenarios and physical fire models . 11
4.2 Factors affecting smoke production . 12
4.2.1 General . 12
4.2.2 Modes of decomposition . 12
4.2.3 Ventilation and the burning environment . 16
4.2.4 Time and temperature . 16
4.2.5 Removal mechanisms for smoke particles. 16
5 Principles of smoke measurement . 16
5.1 General . 16
5.2 Bouguer's law . 16
5.3 Extinction area . 17
5.4 Log units . 18
10
5.5 Light sources . 18
5.6 Specific extinction area of smoke. 18
5.7 Mass optical density of smoke . 19
5.8 Visibility . 20
6 Static and dynamic methods . 20
6.1 Static methods . 20
6.1.1 Principles . 20
6.1.2 Extinction area of smoke . 20
6.1.3 Specific optical density of smoke . 21
6.1.4 Prediction of visibility . 21
6.2 Dynamic methods . 21
6.2.1 Principles . 21
6.2.2 Smoke production rate . 21
6.2.3 Total smoke production . 22
6.2.4 SMOGRA index . 22
7 Test methods . 23
7.1 Consideration of test methods . 23
7.2 Selection of test specimen . 24
8 Presentation of data . 24
9 Relevance of data to hazard assessment . 24
Annex A (informative) Calculation of visibility . 27
A.1 General . 27
A.2 Example. 27
Annex B (informative) Relationships between D and some other smoke parameters
s
as measured in ISO 5659-2 [4] . 29
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Annex C (informative) Relationships between per cent transmission, as measured in a
"three metre cube" enclosure, and extinction area . 31
Bibliography . 33
Figure 1 – Different phases in the development of a fire within a compartment . 12
Figure 2 – Attenuation of light by smoke . 17
Figure 3 – Extinction area . 18
Figure 4 – Dynamic smoke measurement . 21
Figure 5 – Example SPRav versus t curve . 23
Figure 6 – SMOGRA curve derived from Figure 5 . 23
Figure 7 – Evaluation and consideration of smoke test methods . 26
Figure A.1 – Visibility (ω) versus extinction coefficient (k) . 27
Figure B.1 – Smoke parameters related to D as measured in ISO 5659-2 . 30
s
Figure C.1 – Extinction area (amount of smoke) related to per cent transmission as
measured in the "three metre cube" . 32
Table 1 – Characteristics of fire stages (from Table 1 in ISO 19706:2011) . 14
Table B.1 – Conversion from D to some other smoke parameters as measured in
s
ISO 5659-2 . 29
Table C.1 – Conversions from per cent transmission, as measured in the "three metre
cube" to amount of smoke (extinction area) . 31
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INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIRE HAZARD TESTING –
Part 6-1: Smoke obscuration –
General guidance
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.
International Standard IEC 60695-6-1 has been prepared by IEC technical committee 89: Fire
hazard testing.
This third edition cancels and replaces the second edition of IEC 60695-6-1 published in 2005
and Amendment 1:2010. It constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
– References to IEC TS 60695-6-30 (withdrawn in 2016) have been removed.
– References to IEC TS 60695-6-31 (withdrawn in 2016) have been removed.
– References to ISO 5659-2 have been inserted.
– The scope contains some additional text.
– Terms and definitions have been updated.
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IEC 60695-6-1:2021 © IEC 2021 – 5 –
– Subclause 3.2 has been updated.
– Subclause 7.1 has been updated.
The text of this International Standard is based on the following documents:
Draft Report on voting
89/1472/CDV 89/1504/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.
It has the status of a basic safety publication in accordance with IEC Guide 104 and
ISO/IEC Guide 51.
This International Standard is to be used in conjunction with IEC 60695-6-2.
In this standard, the following print types are used:
• italic font: terms defined in Clause 3.
A list of all parts in the IEC 60695 series, published under the general title Fire hazard testing,
can be found on the IEC website.
IEC 60695-6 consists of the following parts:
Part 6-1: Smoke obscuration – General guidance
Part 6-2: Smoke obscuration – Summary and relevance of test methods
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.
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.
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INTRODUCTION
In the design of an 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 the risk of fire to a
tolerable level even in the event of reasonably foreseeable (mis)use, malfunction or failure.
1
IEC 60695-1-10, IEC 60695-1-11, and IEC 60695-1-12 [1] provide guidance on how this is to
be accomplished.
Fires involving electrotechnical products can also 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 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.
One of the contributing hazards is the release of smoke, which may cause loss of vision
and/or disorientation which could impede escape from the building or fire fighting.
Smoke particles reduce the visibility due to light absorption and scattering. Consequently,
people may experience difficulties in finding exit signs, doors and windows. Visibility is often
determined as the distance at which an object is no longer visible. It depends on many
factors, but close relationships have been established between visibility and the
measurements of the extinction coefficient of smoke – see Annex A.
The production of smoke and its optical properties can be measured as well as other fire
properties, such as heat release, flame spread, and the production of toxic gas and corrosive
effluent. This document serves as a guidance document and focuses on obscuration of light
by smoke.
___________
1
Numbers in square brackets refer to the bibliography.
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IEC 60695-6-1:2021 © IEC 2021 – 7 –
FIRE HAZARD TESTING –
Part 6-1: Smoke obscuration –
General guidance
1 Scope
This part of IEC 60695 gives guidance on:
a) the optical measurement of obscuration of smoke;
b) general aspects of optical smoke test methods;
c) consideration of test methods;
d) expression of smoke test data;
e) the relevance of optical smoke data to hazard assessment.
This basic safety publication focusing on safety guidance is primarily intended for use by
technical committees in the preparation of safety publications 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.
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 60695-4, Fire hazard testing – Part 4: Terminology concerning fire tests for
electrotechnical products
IEC 60695-6-2, Fire hazard testing – Part 6-2: Smoke obscuration – Summary and relevance
of test methods
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
ISO 13943:2017, Fire safety – Vocabulary
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3 Terms, definitions and symbols
3.1 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, 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
3.1.1
extinction area of smoke
product of the volume occupied by smoke (3.1.10) and the extinction coefficient (3.1.2) of the
smoke
2
Note 1 to entry: The extinction area of smoke is a measure of the amount of smoke. The typical unit is m .
[SOURCE: ISO 13943:2017, 3.110]
3.1.2
extinction coefficient
natural logarithm of the ratio of incident light intensity to transmitted light intensity, per unit
light path length
-1
Note 1 to entry: The typical unit is m .
[SOURCE: ISO 13943:2017, 3.111]
3.1.3
mass optical density of smoke
optical density of smoke (3.1.6) multiplied by a factor which is the volume of the test chamber
divided by the product of the mass lost from the test specimen and the light path length
2 −1
Note 1 to entry: The typical unit is m⋅g .
Note 2 to entry: Optical density of smoke = V/(Δm L), where V is test chamber volume, Δm is test specimen mass
loss and L is light path length.
[SOURCE: ISO 13943:2017, 3.265]
3.1.4
obscuration of smoke
reduction in the intensity of light due to its passage through smoke (3.1.10)
Note 1 to entry: Compare with the terms extinction area of smoke (3.1.1), extinction coefficient (3.1.2), opacity of
smoke (3.1.5), optical density of smoke (3.1.6), smoke obscuration (3.1.11), specific extinction area of
smoke (3.1.13) and specific optical density of smoke (3.1.14).
Note 2 to entry: In practice, obscuration of smoke is usually measured as the transmittance which is normally
expressed as a percentage.
Note 3 to entry: The obscuration of smoke causes a reduction in visibility (3.1.6).
[SOURCE: ISO 13943:2017, 3.286]
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3.1.5
opacity of smoke
ratio of incident light intensity to transmitted light intensity through smoke (3.1.10), under
specified conditions
Note 1 to entry: Also, obscuration of smoke (3.1.4), smoke obscuration (3.1.11).
Note 2 to entry: The opacity of smoke is the reciprocal of transmittance.
Note 3 to entry: The opacity of smoke is dimensionless.
[SOURCE: ISO 13943:2017, 3.287]
3.1.6
optical density of smoke
measure of the attenuation of a light beam passing through smoke (3.1.10) expressed as the
logarithm to the base 10 of the opacity of smoke (3.1.5)
Note 1 to entry: Compare with the term specific optical density of smoke (3.1.14).
Note 2 to entry: The optical density of smoke is dimensionless.
[SOURCE: ISO 13943:2017, 3.288]
3.1.7
physical fire model
laboratory process, including the apparatus, the environment and the fire test procedure
intended to represent a certain phase of a fire
[SOURCE: ISO 13943:2017, 3.298]
3.1.8
SMOGRA
smoke growth rate parameter that is a function of the rate of smoke production and the time of
smoke production
Note 1 to entry: Further details are given in 6.2.4.
3.1.9
SMOGRA index
maximum value of SMOGRA (3.1.8) during a defined test period
Note 1 to entry: Further details are given in 6.2.4.
3.1.10
smoke
visible part of a fire effluent
[SOURCE: ISO 13943:2017, 3.347]
3.1.11
smoke obscuration
reduction of light transmission by smoke (3.1.10), as measured by light attenuation
Note 1 to entry: Compare with the terms extinction area of smoke (3.1.1), extinction coefficient (3.1.2),
obscuration of smoke (3.1.4), opacity of smoke (3.1.5), optical density of smoke (3.1.6), specific extinction area of
smoke (3.1.13) and specific optical density of smoke (3.1.14).
[SOURCE: ISO 13943:2017, 3.349]
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3.1.12
smoke production rate
amount of smoke (3.1.10) produced per unit time in a fire
...
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