IEC 60695-6-1:2005

Fire hazard testing - Part 6-1: Smoke obscuration - General guidance

IEC 60695-6-1:2005 Gives guidance on:
a) optical measurement of smoke obscuration;
b) general aspects of optical smoke test methods;
c) consideration of test methods;
d) expression of smoke test data;
e) relevance of optical smoke data to hazard assessment.
The main changes with respect to the previous edition are listed below:
- Modified title.
- Updated normative references.
- Expanded terms and definitions.
- Numerous editorial changes of a technical nature throughout the publication.
- A flowchart has been added for the evaluation and consideration of smoke test methods.

Essais relatifs aux risques du feu - Partie 6-1: Opacité des fumées - Lignes directrices générales

IEC 60695-6-1:2005 Fournit des lignes directrices sur:
a) la mesure optique de l'obscurcissement par la fumée;
b) les aspects généraux des méthodes d'essais optiques de la fumée;
c) des considérations concernant les méthodes d'essais;
d) l'expression des résultats d'essais;
e) la pertinence des résultats des mesures optiques de la fumée pour l'évaluation des risques.
Les principales modifications par rapport à l'édition antérieure sont indiquées ci-dessous:
- Titre modifié.
- Mise à jour des références normatives.
- Ajout de termes et de définitions.
- Nombreuses modifications rédactionnelles de nature technique dans toute la publication.
- Ajout d'un logigramme pour l'évaluation et la considération des méthodes d'essais de fumée.

General Information

• Status: Published
• Publication Date: 02-May-2005
• ICS: 13.220.99 - Other standards related to protection against fire
• ICS: 29.020 - Electrical engineering in general
• Technical Committee: TC 89 - Fire hazard testing
• Drafting Committee: WG 11 - TC 89/WG 11
• Current Stage: DELPUB - Deleted Publication
• Start Date: 05-Aug-2021
• Completion Date: 28-Jun-2019

Relations

• Amended By: IEC 60695-6-1:2005/AMD1:2010 - Amendment 1 - Fire hazard testing - Part 6-1: Smoke obscuration - General guidance
• Effective Date: 05-Sep-2023
• Revised: IEC 60695-6-1:2021 - Fire hazard testing - Part 6-1: Smoke obscuration - General guidance
• Effective Date: 05-Sep-2023
• Revises: IEC 60695-6-1:2001 - Fire hazard testing - Part 6-1: Smoke opacity - General guidance
• Effective Date: 05-Sep-2023

Overview

IEC 60695-6-1:2005, titled Fire hazard testing – Part 6-1: Smoke obscuration – General guidance, is an essential international standard published by the International Electrotechnical Commission (IEC). This document provides comprehensive guidance on the optical measurement of smoke obscuration resulting from fire hazards in electrotechnical products. Released to complement related standards, it offers technical insights on test methods and data interpretation related to smoke generation during fires.

Smoke produced in fires reduces visibility by absorbing and scattering light, posing a significant risk by impairing evacuation and firefighting efforts. IEC 60695-6-1 focuses on measuring this obscuration effect, providing standardized procedures and definitions to enhance safety assessments related to smoke hazards.

Key Topics

• Optical Measurement of Smoke Obscuration
  The standard outlines principles for assessing smoke’s effect on vision by measuring light extinction. This includes using Bouguer’s law to quantify light attenuation and calculating extinction area and mass optical density.

• Smoke Test Methods
  IEC 60695-6-1 describes both static and dynamic testing methods for smoke evaluation. It discusses the selection of appropriate test specimens and test conditions to simulate realistic fire scenarios.

• Expression of Smoke Data
  Smoke measurements are expressed through parameters such as extinction coefficient, specific extinction area, and visibility distances. The standard provides mathematical relationships and symbols essential for interpreting test results.

• Guidance on Test Method Consideration
  A key addition is a flowchart guiding users through the evaluation and choice of smoke test methods suitable for different applications.

• Relevance to Hazard Assessment
  The standard emphasizes interpreting smoke test data within the context of fire hazard evaluation, linking optical density metrics to practical consequences like reduced visibility and increased escape difficulty.

• Updated Terms and Definitions
  The document features expanded terminology and normative references, ensuring clarity and consistency for testing professionals.

Applications

IEC 60695-6-1:2005 is foundational for industries involved in:

• Electrical and Electronic Equipment Manufacturing
  Assisting designers and safety engineers to evaluate fire safety and smoke emission characteristics of components, circuits, and finished products.

• Fire Safety Testing and Certification
  Serving as a reference for laboratories conducting smoke obscuration tests to comply with regulatory and safety requirements.

• Risk Management in Buildings and Facilities
  Informing fire hazard analysis by quantifying smoke visibility reduction impact on evacuation and emergency response.

• Development of Fire Protection Systems
  Providing data to optimize smoke detection, ventilation, and suppression systems for enhanced indoor safety.

• Research and Standardization
  Supporting further technical developments in smoke measurement techniques and integration into broader fire hazard standards.

Related Standards

IEC 60695-6-1 is part of the IEC 60695 series on fire hazard testing, closely linked to:

• IEC 60695-6-2: Smoke obscuration – Summary and relevance of test methods
  Offers supplementary insights on smoke test applications and interpretations.

• IEC 60695-6-30: Small scale static method – Determination of smoke opacity – Description of apparatus
  Specifies apparatus and procedures for static smoke opacity tests.

• IEC 60695-6-31: Small-scale static test – Materials
  Focuses on materials testing under controlled smoke obscuration test conditions.

For a full understanding of fire hazard assessment related to smoke, these standards should be used in conjunction to ensure comprehensive and harmonized testing methodologies.

---

Keywords: IEC 60695-6-1, fire hazard testing, smoke obscuration, optical smoke measurement, smoke test methods, fire safety, smoke visibility, extinction coefficient, electrotechnical fire risk, smoke hazard assessment.

Standards Content (Sample)

NORME CEI
INTERNATIONALE
IEC
60695-6-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2005-05
PUBLICATION FONDAMENTALE DE SÉCURITÉ
BASIC SAFETY PUBLICATION
Essais relatifs aux risques du feu –
Partie 6-1:
Opacité des fumées –
Lignes directrices générales
Fire hazard testing –
Part 6-1:
Smoke obscuration –
General guidance
Numéro de référence
Reference number
CEI/IEC 60695-6-1:2005
Numérotation des publications Publication numbering
Depuis le 1er janvier 1997, les publications de la CEI As from 1 January 1997 all IEC publications are
sont numérotées à partir de 60000. Ainsi, la CEI 34-1 issued with a designation in the 60000 series. For
devient la CEI 60034-1. example, IEC 34-1 is now referred to as IEC 60034-1.
Editions consolidées Consolidated editions
Les versions consolidées de certaines publications de la The IEC is now publishing consolidated versions of its
CEI incorporant les amendements sont disponibles. Par publications. For example, edition numbers 1.0, 1.1
exemple, les numéros d’édition 1.0, 1.1 et 1.2 indiquent and 1.2 refer, respectively, to the base publication,
respectivement la publication de base, la publication de the base publication incorporating amendment 1 and
base incorporant l’amendement 1, et la publication de the base publication incorporating amendments 1
base incorporant les amendements 1 et 2. and 2.
Informations supplémentaires Further information on IEC publications
sur les publications de la CEI
Le contenu technique des publications de la CEI est The technical content of IEC publications is kept
constamment revu par la CEI afin qu'il reflète l'état under constant review by the IEC, thus ensuring that
actuel de la technique. Des renseignements relatifs à the content reflects current technology. Information
cette publication, y compris sa validité, sont dispo- relating to this publication, including its validity, is
nibles dans le Catalogue des publications de la CEI available in the IEC Catalogue of publications
(voir ci-dessous) en plus des nouvelles éditions, (see below) in addition to new editions, amendments
amendements et corrigenda. Des informations sur les and corrigenda. Information on the subjects under
sujets à l’étude et l’avancement des travaux entrepris consideration and work in progress undertaken by the
par le comité d’études qui a élaboré cette publication, technical committee which has prepared this
ainsi que la liste des publications parues, sont publication, as well as the list of publications issued,
également disponibles par l’intermédiaire de: is also available from the following:
• Site web de la CEI (www.iec.ch) • IEC Web Site (www.iec.ch)
• Catalogue des publications de la CEI • Catalogue of IEC publications
Le catalogue en ligne sur le site web de la CEI The on-line catalogue on the IEC web site
(www.iec.ch/searchpub) vous permet de faire des (www.iec.ch/searchpub) enables you to search by a
recherches en utilisant de nombreux critères, variety of criteria including text searches,
comprenant des recherches textuelles, par comité technical committees and date of publication. On-
d’études ou date de publication. Des informations en line information is also available on recently
ligne sont également disponibles sur les nouvelles issued publications, withdrawn and replaced
publications, les publications remplacées ou retirées, publications, as well as corrigenda.
ainsi que sur les corrigenda.
• IEC Just Published • IEC Just Published
Ce résumé des dernières publications parues This summary of recently issued publications
(www.iec.ch/online_news/justpub) est aussi dispo- (www.iec.ch/online_news/justpub) is also available
nible par courrier électronique. Veuillez prendre by email. Please contact the Customer Service
contact avec le Service client (voir ci-dessous) Centre (see below) for further information.
pour plus d’informations.
• Service clients • Customer Service Centre
Si vous avez des questions au sujet de cette If you have any questions regarding this
publication ou avez besoin de renseignements publication or need further assistance, please
supplémentaires, prenez contact avec le Service contact the Customer Service Centre:
clients:
Email: [e-mail] Email: [e-mail]
Tél: [phone] Tel: [phone]
Fax: [phone] Fax: [phone]
.
NORME CEI
INTERNATIONALE
IEC
60695-6-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2005-05
PUBLICATION FONDAMENTALE DE SÉCURITÉ
BASIC SAFETY PUBLICATION
Essais relatifs aux risques du feu –
Partie 6-1:
Opacité des fumées –
Lignes directrices générales
Fire hazard testing –
Part 6-1:
Smoke obscuration –
General guidance
 IEC 2005 Droits de reproduction réservés  Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
CODE PRIX
V
PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

– 2 – 60695-6-1  CEI:2005
SOMMAIRE
AVANT-PROPOS .6
INTRODUCTION.10

1 Domaine d’application.12
2 Références normatives .12
3 Termes, définitions et symboles .14
3.1 Termes et définitions .14
3.2 Symboles .20
4 Aspects généraux des méthodes d’essais relatives à la fumée .22
4.1 Scénarios et modèles feu .22
4.2 Facteurs affectant la production de fumée.26
5 Principes de mesure de la fumée .28
5.1 Loi de Bouguer .28
5.2 Surface d’extinction .30
5.3 Unités log .32
5.4 Sources lumineuses .32
5.5 Surface d’extinction spécifique.32
5.6 Densité optique massique.34
5.7 Visibilité.36
6 Méthodes statiques et dynamiques.36
6.1 Méthodes statiques.36
6.2 Méthodes dynamiques .36
7 Méthodes d'essais .40
7.1 Considérations sur les méthodes d’essais.40
7.2 Sélection de l’éprouvette d’essai.40
8 Présentation des résultats.40
9 Relation entre les données et l’évaluation du risque .42

Annexe A (informative) Calcul de la visibilité.46
Annexe B (informative) Relations entre D et certains autres paramètres relatifs à la
s
fumée mesurés suivant la CEI 60695-6-30 et la CEI 60695-6-31.50
Annexe C (informative) Relations entre le pourcentage de transmission mesuré dans
une enceinte cubique de 3 m («three metre cube») et la surface d’extinction .56

Bibliographie .60

Figure 1 – Diagramme représentant les différentes phases du développement d’un feu
à l’intérieur d’un local .24
Figure 2 – Atténuation de la lumière par la fumée .30
Figure 3 – Surface d’extinction .30
Figure 4 – Mesure dynamique de la fumée .38
Figure 5 – Evaluation et considération des méthodes d’essais de fumée.44

60695-6-1  IEC:2005 – 3 –
CONTENTS
FOREWORD.7
INTRODUCTION.11

1 Scope.13
2 Normative references.13
3 Terms, definitions and symbols .15
3.1 Terms and definitions .15
3.2 Symbols .21
4 General aspects of smoke test methods.23
4.1 Fire scenarios and fire models .23
4.2 Factors affecting smoke production.27
5 Principles of smoke measurement.29
5.1 Bouguer’s law.29
5.2 Extinction area.31
5.3 Log units .33
5.4 Light sources.33
5.5 Specific extinction area.33
5.6 Mass optical density .35
5.7 Visibility.37
6 Static and dynamic methods .37
6.1 Static methods.37
6.2 Dynamic methods .37
7 Test methods.41
7.1 Consideration of test methods.41
7.2 Selection of test specimen .41
8 Presentation of data.41
9 Relevance of data to hazard assessment .43

Annex A (informative) Calculation of visibility.47
Annex B (informative) Relationships between D and some other smoke parameters as
s
measured in IEC 60695-6-30 and IEC 60695-6-31 .51
Annex C (informative) Relationships between percent transmission, as measured in a
"three metre cube" enclosure, and extinction area .57

Bibliography .61

Figure 1 – Chart of different phases in the development of a fire within a compartment .25
Figure 2 – Attenuation of light by smoke .31
Figure 3 – Extinction area .31
Figure 4 – Dynamic smoke measurement .39
Figure 5 – Evaluation and consideration of smoke test methods .45

– 4 – 60695-6-1  CEI:2005
Figure A.1 – Visibilité (ω) en fonction du coefficient d’extinction (k) .46
Figure B.1 – Paramètres relatifs à la fumée se rapportant à D , mesurés suivant la
s
CEI 60695-6-30 et la CEI 60695-6-31 .54
Figure C.1 – Rapport entre la surface d’extinction (quantité de fumée) et le pourcentage
de transmission mesuré dans l'enceinte «three metre cube».58

Tableau 1 – Classification générale des feux (ISO/TR 9122-1).24
Tableau B.1 – Conversion de D en d’autres paramètres relatifs à la fumée mesurés
s
suivant la CEI 60695-6-30 et la CEI 60695-6-31 .52
Tableau C.1 – Conversion du pourcentage de transmission mesuré dans l'enceinte
«three metre cube» en quantité de fumée (surface d’extinction).56

60695-6-1  IEC:2005 – 5 –
Figure A.1 – Visibility (ω) versus extinction coefficient (k).47
Figure B.1 – Smoke parameters related to D as measured in IEC 60695-6-30 and
s
IEC 60695-6-31 .55
Figure C.1 – Extinction area (amount of smoke) related to percent transmission as
measured in the "three metre cube" .59

Table 1 – General classification of fires (ISO/TR 9122-1) .25
Table B.1 – Conversion from D to some other smoke parameters as measured in
s
IEC 60695-6-30 and IEC 60695-6-31 .53
Table C.1 – Conversions from percent transmission, as measured in the “three metre
cube” to amount of smoke (extinction area).57

– 6 – 60695-6-1  CEI:2005
COMMISSION ÉLECTROTECHNIQUE INTERNATIONALE
____________
ESSAIS RELATIFS AUX RISQUES DU FEU –

Partie 6-1: Opacité des fumées –
Lignes directrices générales
AVANT-PROPOS
1) La Commission Electrotechnique Internationale (CEI) est une organisation mondiale de normalisation composée
de l'ensemble des comités électrotechniques nationaux (Comités nationaux de la CEI). La CEI a pour objet de
favoriser la coopération internationale pour toutes les questions de normalisation dans les domaines de
l'électricité et de l'électronique. A cet effet, la CEI – entre autres activités – publie des Normes internationales,
des Spécifications techniques, des Rapports techniques, des Spécifications accessibles au public (PAS) et des
Guides (ci-après dénommés "Publication(s) de la CEI"). Leur élaboration est confiée à des comités d'études,
aux travaux desquels tout Comité national intéressé par le sujet traité peut participer. Les organisations
internationales, gouvernementales et non gouvernementales, en liaison avec la CEI, participent également aux
travaux. La CEI collabore étroitement avec l'Organisation Internationale de Normalisation (ISO), selon des
conditions fixées par accord entre les deux organisations.
2) Les décisions ou accords officiels de la CEI concernant les questions techniques représentent, dans la mesure
du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux de la CEI
intéressés sont représentés dans chaque comité d’études.
3) Les Publications de la CEI se présentent sous la forme de recommandations internationales et sont agréées
comme telles par les Comités nationaux de la CEI. Tous les efforts raisonnables sont entrepris afin que la CEI
s'assure de l'exactitude du contenu technique de ses publications; la CEI ne peut pas être tenue responsable de
l'éventuelle mauvaise utilisation ou interprétation qui en est faite par un quelconque utilisateur final.
4) Dans le but d'encourager l'uniformité internationale, les Comités nationaux de la CEI s'engagent, dans toute la
mesure possible, à appliquer de façon transparente les Publications de la CEI dans leurs publications
nationales et régionales. Toutes divergences entre toutes Publications de la CEI et toutes publications
nationales ou régionales correspondantes doivent être indiquées en termes clairs dans ces dernières.
5) La CEI n’a prévu aucune procédure de marquage valant indication d’approbation et n'engage pas sa
responsabilité pour les équipements déclarés conformes à une de ses Publications.
6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication.
7) Aucune responsabilité ne doit être imputée à la CEI, à ses administrateurs, employés, auxiliaires ou
mandataires, y compris ses experts particuliers et les membres de ses comités d'études et des Comités
nationaux de la CEI, pour tout préjudice causé en cas de dommages corporels et matériels, ou de tout autre
dommage de quelque nature que ce soit, directe ou indirecte, ou pour supporter les coûts (y compris les frais
de justice) et les dépenses découlant de la publication ou de l'utilisation de cette Publication de la CEI ou de
toute autre Publication de la CEI, ou au crédit qui lui est accordé.
8) L'attention est attirée sur les références normatives citées dans cette publication. L'utilisation de publications
référencées est obligatoire pour une application correcte de la présente publication.
9) L’attention est attirée sur le fait que certains des éléments de la présente Publication de la CEI peuvent faire
l’objet de droits de propriété intellectuelle ou de droits analogues. La CEI ne saurait être tenue pour
responsable de ne pas avoir identifié de tels droits de propriété et de ne pas avoir signalé leur existence.
La Norme internationale CEI 60695-6-1 a été établie par le comité d'études 89 de la CEI:
Essais relatifs aux risques du feu.
Cette seconde édition annule et remplace la première édition de la CEI 60695-6-1, publiée en
2001, dont elle constitue une révision technique.
Les principales modifications par rapport à l'édition antérieure sont indiquées ci-dessous:
– Titre modifié.
– Mise à jour des références normatives.
– Ajout de termes et de définitions.
– Nombreuses modifications rédactionnelles de nature technique dans toute la publication.
– Ajout d’un logigramme pour l’évaluation et la considération des méthodes d’essais de
fumée.
60695-6-1  IEC:2005 – 7 –
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 second edition cancels and replaces the first edition of IEC 60695-6-1 published in 2001.
It constitutes a technical revision.
The main changes with respect to the previous edition are listed below:
– Modified title.
– Updated normative references.
– Expanded terms and definitions.
– Numerous editorial changes of a technical nature throughout the publication.
– A flowchart has been added for the evaluation and consideration of smoke test methods.

– 8 – 60695-6-1  CEI:2005
Elle a le statut de publication fondamentale de sécurité, conformément au Guide CEI 104 et au
Guide ISO/CEI 51.
Le texte de la présente norme est issu des documents suivants:
FDIS Rapport de vote
89/692/FDIS 89/696/RVD
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant
abouti à l'approbation de cette norme.
La présente norme doit être utilisée conjointement avec la CEI 60695-6-2.
Cette publication a été rédigée selon les Directives ISO/CEI, Partie 2.
La série CEI 60695-6, sous le titre général Essais relatifs aux risques du feu, comprend les
parties suivantes
Partie 6-1: Opacité des fumées – Lignes directrices générales
Partie 6-2: Opacité des fumées – Résumé et pertinence des méthodes d'essais
Partie 6-30: Opacité des fumées – Guide et méthodes d’essai pour l’évaluation des dangers
d’obscurcissement de la vision par les fumées provenant de produits
électrotechniques impliqués dans des feux – Méthode statique à petite échelle –
Détermination de l’opacité des fumées – Description de l’appareillage
Partie 6-31: Opacité des fumées – Méthode statique à petite échelle – Matériaux
Le comité a décidé que le contenu de cette publication ne sera pas modifié avant la date de
maintenanceindiquée sur le site web de la CEI sous "http://webstore.iec.ch" dans les données
relatives à la publication recherchée. A cette date, la publication sera
• reconduite,
• supprimée,
• remplacée par une édition révisée, ou
• amendée.
60695-6-1  IEC:2005 – 9 –
It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC
Guide 51.
The text of this standard is based on the following documents:
FDIS Report on voting
89/692/FDIS 89/696/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This standard is to be used in conjunction with IEC 60695-6-2.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The IEC 60695-6 series, under the general heading Fire hazard testing, consists of the
following parts
Part 6-1: Smoke obscuration – General guidance
Part 6-2: Smoke obscuration – Summary and relevance of test methods
Part 6-30: Smoke obscuration – Guidance and test methods on the assessment of
obscuration hazard of vision caused by smoke opacity from electrotechnical
products involved in fires – Small scale static method - Determination of smoke
opacity - Description of the apparatus
Part 6-31: Smoke obscuration – Small-scale static test – Materials
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 10 – 60695-6-1  CEI:2005
INTRODUCTION
Il faut prendre en compte le risque de feu dans tout circuit électrique et l’objectif de la
conception des composants, des circuits ou des équipements, ainsi que le choix des
matériaux, est de réduire la probabilité d’un incendie même dans l’éventualité d’une utilisation
anormale, d’un mauvais fonctionnement ou d’une défaillance prévisibles.
Les produits électrotechniques, initialement victimes de l’incendie, peuvent contribuer à
l’incendie. L’un des risques y participant est la production de fumée, qui peut entraîner une
perte de vision et/ou une désorientation pouvant entraver l’évacuation des immeubles ou la
lutte contre l’incendie.
Les particules de fumée réduisent la visibilité du fait de l’absorption de la lumière et de sa
diffusion. En conséquence, les personnes peuvent avoir des difficultés à trouver les signaux de
sortie, les portes et les fenêtres. La visibilité est souvent définie comme étant la distance à
partir de laquelle un objet n’est plus visible. Elle dépend de nombreux facteurs, mais des
relations étroites ont été établies entre la visibilité et les mesures du coefficient d’extinction de
la fumée – voir Annexe A.
La production de fumée et ses propriétés optiques peuvent être mesurées avec d’autres
propriétés du feu telles que le dégagement de chaleur, la propagation des flammes, et la
production de gaz toxiques et d’effluents corrosifs. La présente partie de la CEI 60695-6 sert
de guide et traite de l’obscurcissement de la lumière par la fumée.

60695-6-1  IEC:2005 – 11 –
INTRODUCTION
The risk of fire needs to be considered in any electrical circuit, and the objective of component,
circuit and equipment design, as well as the choice of material, is to reduce the likelihood of
fire, even in the event of foreseeable abnormal use, malfunction or failure.
Electrotechnical products, primarily victims of a fire, may nevertheless contribute to the fire.
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 part of IEC 60695-6 serves as a guidance document and focuses on obscuration
of light by smoke.
– 12 – 60695-6-1  CEI:2005
ESSAIS RELATIFS AUX RISQUES DU FEU –

Partie 6-1: Opacité des fumées –
Lignes directrices générales
1 Domaine d’application
La présente partie de la CEI 60695 fournit des lignes directrices sur:
a) la mesure optique de l’obscurcissement par la fumée;
b) les aspects généraux des méthodes d’essais optiques de la fumée;
c) des considérations concernant les méthodes d’essais;
d) l’expression des résultats d’essais;
e) la pertinence des résultats des mesures optiques de la fumée pour l’évaluation des risques.
L’une des responsabilités d’un comité d’études consiste, le cas échéant, à utiliser les publica-
tions fondamentales de sécurité dans le cadre de l’élaboration de ses publications.
2 Références normatives
Les documents de référence suivants sont indispensables pour l'application du présent
document. Pour les références datées, seule l'édition citée s'applique. Pour les références non
datées, la dernière édition du document de référence s'applique (y compris les éventuels
amendements
CEI 60695-1-1, Essais relatifs aux risques du feu – Partie 1-1: Guide pour l’évaluation des
risques du feu des produits électrotechniques – Directives générales
CEI 60695-4:2001 , Essais relatifs aux risques du feu – Partie 4: Terminologie relative aux
essais au feu
CEI 60695-6-2:2001, Essais relatifs aux risques du feu – Partie 6-2: Opacité des fumées –
Résumé et pertinence des méthodes d'essais
CEI 60695-6-30, Essais relatifs aux risques du feu – Partie 6: Guide et méthodes d’essai pour
l’évaluation des dangers d’obscurcissement de la vision par les fumées provenant de produits
électrotechniques impliqués dans des feux – Section 30: Méthode statique à petite échelle –
Détermination de l’opacité des fumées – Description de l’appareillage
CEI 60695-6-31, Essais relatifs aux risques du feu – Partie 6-31: Opacité des fumées –
Méthode statique à petite échelle – Matériaux
Guide CEI 104:1997, Elaboration des publications de sécurité et utilisation des publications
fondamentales de sécurité et publications groupées de sécurité
ISO/TR 9122-1:1989, Essais de toxicité des effluents du feu – Partie 1: Généralités
___________
Edition consolidée 2.2 (2001) qui comprend la CEI 60695-4 (1993) ainsi que l'amendement 1 (1995) et
l’amendement 2 (2001).
60695-6-1  IEC:2005 – 13 –
FIRE HAZARD TESTING –
Part 6-1: Smoke obscuration –
General guidance
1 Scope
This part of IEC 60695 gives guidance on:
a) optical measurement of smoke obscuration;
b) general aspects of optical smoke test methods;
c) consideration of test methods;
d) expression of smoke test data;
e) relevance of optical smoke data to hazard assessment.
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 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.
IEC 60695-1-1, Fire hazard testing – Part 1-1: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines
IEC 60695-4:2001 , Fire hazard testing – Part 4: Terminology concerning fire tests
IEC 60695-6-2:2001, Fire hazard testing – Part 6-2: Smoke obscuration – Summary and
relevance of test methods
IEC 60695-6-30, Fire hazard testing – Part 6: Guidance and test methods on the assessment of
obscuration hazard of vision caused by smoke opacity from electrotechnical products involved
in fires – Section 30: Small-scale static method – Determination of smoke opacity – Description
of the apparatus
IEC 60695-6-31, Fire hazard testing – Part 6-31: Smoke obscuration – Small-scale static test –
Materials
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/TR 9122-1:1989, Toxicity testing of fire effluents – Part 1: General
___________
Consolidated edition 2.2 (2001) that includes IEC 60695-4 (1993), its amendment 1 (1995) and its amendment 2
(2001).
– 14 – 60695-6-1  CEI:2005
ISO 5659-2:1994, Plastiques – Production de fumée – Partie 2: Détermination de la densité
optique par un essai en enceinte unique
ISO/CEI 13943:2000, Sécurité au feu – Vocabulaire
ISO/CEI Guide 51:1999, Aspects liés à la sécurité – Principes directeurs pour les inclure dans
les normes
3 Termes, définitions et symboles
3.1 Termes et définitions
Pour les besoins du présent document, les termes, définitions et symboles suivants
s'appliquent.
3.1.1
combustion
réaction exothermique d'une substance avec un comburant
NOTE La combustion émet généralement des effluents accompagnés de flammes et/ou d'incandescence.
[ISO/CEI 13943, définition 23]
3.1.2
surface d’extinction de la fumée
produit du coefficient d’extinction par le volume occupé par la fumée
NOTE C’est une mesure de quantité de fumée.
[CEI 60695-4, définition 2.130]
3.1.3
coefficient d’extinction de la fumée
logarithme népérien de l’opacité de la fumée divisé par la longueur du faisceau lumineux utilisé
pour mesurer l’opacité de la fumée
[CEI 60695-4, définition 2.131]
3.1.4
feu; incendie
a) feu: combustion caractérisée par une émission de chaleur et d'effluents accompagnée de
fumée et/ou de flammes et/ou d'incandescence;
b) incendie: combustion rapide qui se développe sans contrôle dans le temps et dans l'espace
[CEI 60695-4, définition 2.29]
3.1.5
effluents du feu
ensemble des gaz, particules ou aérosols dégagés par combustion ou pyrolyse
[CEI 60695-4, définition 2.33]
3.1.6
risques du feu; danger d’incendie
possibilité de blessures ou de perte de la vie et/ou de dégâts matériels que représente un
incendie
[CEI 60695-4, définition 2.36]

60695-6-1  IEC:2005 – 15 –
ISO 5659-2:1994, Plastics – Smoke generation – Part 2: Determination of optical density by a
single-chamber test
ISO/IEC 13943:2000, Fire safety – Vocabulary
ISO/IEC Guide 51:1999. Safety aspects – Guidelines for inclusion in standards
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purpose of this document, the following terms, definitions and symbols apply.
3.1.1
combustion
exothermic reaction of a substance with an oxidizer
NOTE Combustion generally emits effluent accompanied by flames and/or visible light.
[ISO/IEC 13943, definition 23]
3.1.2
extinction area of smoke
product of the extinction coefficient and the volume occupied by the smoke
NOTE It is a measure of the amount of smoke.
[IEC 60695-4, definition 2.130]
3.1.3
extinction coefficient of smoke
natural logarithm of the opacity of smoke divided by the path length of the light used to
measure the smoke opacity
[IEC 60695-4, definition 2.131]
3.1.4
fire
a) process of combustion characterized by the emission of heat and effluent accompanied by
smoke, and/or flame, and/or glowing;
b) rapid combustion spreading uncontrolled in time and space
[IEC 60695-4, definition 2.29]
3.1.5
fire effluent
total gaseous, particulate or aerosol effluent from combustion or pyrolysis
[IEC 60695-4, definition 2.33]
3.1.6
fire hazard
potential for injury or loss of life and/or damage to property by fire
[IEC 60695-4, definition 2.36]

– 16 – 60695-6-1  CEI:2005
3.1.7
modèle feu
procédé de laboratoire, incluant aussi bien l’appareillage que le mode opératoire, destiné à
simuler une certaine étape d’un feu réel
[CEI 60695-4, définition 2.120]
3.1.8
scénario feu
description détaillée des conditions, y compris de l’environnement, dans lesquelles se
déroulent une ou plusieurs étapes d'un feu réel à un emplacement spécifique ou d'une
simulation dans un essai en vraie grandeur, depuis la situation avant le début jusqu'à la fin de
la combustion
[ISO/CEI 13943, définition 58]
3.1.9
embrasement éclair; flash-over
passage brusque à l'état de combustion généralisée en surface de l'ensemble des matériaux
combustibles dans un espace fermé
[CEI 60695-4, définition 2.59]
3.1.10
éclairement énergétique
quantité d'énergie thermique émise, transmise ou reçue par unité de surface et de temps
NOTE Il est exprimée en watts par mètre carré.
[ISO/CEI 13943, définition 85]
3.1.11
allumage
action d'allumer
NOTE Le terme “ignition” a en français un sens très différent [état d'un corps en combustion].
[ISO/CEI 13943, définition 96]
3.1.12
essai à grande échelle
essai dont la taille dépasse celle d’un essai sur une paillasse typique de laboratoire
[CEI 60695-4, définition 2.122]
3.1.13
densité optique massique de la fumée
densité optique multipliée par un facteur, V /(L × Δm), où V est le volume de la chambre d’essai,
Δm est la perte de masse de l’éprouvette d'essai et L est la longueur du faisceau lumineux
[CEI 60695-4, définition 2.133]
3.1.14
opacité (de la fumée)
rapport (I/T) du flux lumineux incident (I) au flux lumineux transmis (T) à travers la fumée, dans
des conditions d’essai spécifiées
[CEI 60695-4, définition 2.89]

60695-6-1  IEC:2005 – 17 –
3.1.7
fire model
a laboratory process, including both the apparatus and the mode of operation, intended to
simulate a certain stage of a real fire
[IEC 60695-4, definition 2.120]
3.1.8
fire scenario
detailed description of conditions, including environmental, of one or more stages from before
ignition to after completion of combustion in an actual fire at a specific location or in a real-
scale simulation
[ISO/IEC 13943, definition 58]
3.1.9
flash-over
the rapid transition to a state of total surface involvement in a fire of combustible materials
within an enclosure
[IEC 60695-4, definition 2.59]
3.1.10
heat flux
amount of thermal energy emitted, transmitted or received per unit area and unit time
NOTE It is expressed in watts per square metre.
[ISO/IEC 13943, definition 85]
3.1.11
ignition
initiation of combustion
NOTE The term "ignition" in French has a very different meaning [state of body combustion].
[ISO/IEC 13943, definition 96]
3.1.12
large scale test
a test, the size of which exceeds that of a typical laboratory bench test
[IEC 60695-4, definition 2.122]
3.1.13
mass optical density of smoke
optical density multiplied by a factor, V /(L × Δm), where V is the volume of the test chamber,
Δm is the mass loss of the test specimen and L is the light path length
[IEC 60695-4, definition 2.133]
3.1.14
opacity (of smoke)
the ratio (I/T) of incident luminous flux (I) to transmitted luminous flux (T) through smoke,
under specified test conditions
[IEC 60695-4, definition 2.89]

– 18 – 60695-6-1  CEI:2005
3.1.15
densité optique (de la fumée) [lg(I/T)]
logarithme décimal de l’opacité de la fumée (voir aussi densité optique spécifique)
[CEI 60695-4, définition 2.90]
3.1.16
essai en vraie grandeur
essai qui simule une situation d’utilisation finale dans la taille et le décor environnant
[CEI 60695-4, définition 2.123]
3.1.17
essai à petite échelle
essai qui peut être effectué sur une paillasse typique de laboratoire
[CEI 60695-4, définition 2.124]
3.1.18
fumée
ensemble visible de particules solides et/ou liquides en suspension dans les gaz résultant d'une
combustion ou d'une pyrolyse
[CEI 60695-4, définition 2.101]
3.1.19
obscurcissement par la fumée
réduction de la visibilité due à la fumée
[CEI 60695-4, définition 2.102]
3.1.20
vitesse de production de fumée
surface d’extinction de la fumée produite, par unité de temps, par la combustion d’un matériau
dans des conditions d’essai spécifiées
3.1.21
vitesse de dégagement de fumée
voir «vitesse de production de fumée»
3.1.22
surface spécifique d’extinction de la fumée
surface d’extinction de la fumée divisée par la perte de masse de l’éprouvette
[CEI 60695-4, définition 2.137]
3.1.23
densité optique spécifique (de la fumée)
densité optique multipliée par un facteur géométrique V /AL, où V est le volume de la chambre
d’essai, A est l’aire de la surface exposée de l’éprouvette, et L est la longueur du faisceau
lumineux
NOTE L’utilisation du terme ‘spécifique’ ne signifie pas, dans ce cas-ci, 'masse par unité’, mais plutôt une quantité
sans dimension associée à un appareillage d’essai particulier et à une aire de surface d’éprouvette.
3.1.24
visibilité
distance maximale à laquelle un objet de taille, de brillance et de contraste définis peut être vu
et reconnu
60695-6-1  IEC:2005 – 19 –
3.1.15
optical density (of smoke) [lg(I/T)]
common logarithm of the opacity of smoke (see also specific optical density
...

IEC 60695-6-1 ®
Edition 2.1 2010-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Fire hazard testing –
Part 6-1: Smoke obscuration – General guidance

Essais relatifs aux risques du feu –
Partie 6-1: Opacité des fumées – Lignes directrices générales

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by

any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IEC or

IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,
please contact the address below or your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de la CEI ou du Comité national de la CEI du pays du demandeur.

Si vous avez des questions sur le copyright de la CEI ou si vous désirez obtenir des droits supplémentaires sur cette

publication, utilisez les coordonnées ci-après ou contactez le Comité national de la CEI de votre pays de résidence.

IEC Central Office
3, rue de Varembé
CH-1211 Geneva 20
Switzerland
Email: [e-mail]
Web: www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]
A propos de la CEI
La Commission Electrotechnique Internationale (CEI) est la première organisation mondiale qui élabore et publie des
normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications CEI
Le contenu technique des publications de la CEI est constamment revu. Veuillez vous assurer que vous possédez
l’édition la plus récente, un corrigendum ou amendement peut avoir été publié.
ƒ Catalogue des publications de la CEI: www.iec.ch/searchpub/cur_fut-f.htm
Le Catalogue en-ligne de la CEI vous permet d’effectuer des recherches en utilisant différents critères (numéro de référence,
texte, comité d’études,…). Il donne aussi des informations sur les projets et les publications retirées ou remplacées.
ƒ Just Published CEI: www.iec.ch/online_news/justpub
Restez informé sur les nouvelles publications de la CEI. Just Published détaille deux fois par mois les nouvelles
publications parues. Disponible en-ligne et aussi par email.
ƒ Electropedia: www.electropedia.org
Le premier dictionnaire en ligne au monde de termes électroniques et électriques. Il contient plus de 20 000 termes et
définitions en anglais et en français, ainsi que les termes équivalents dans les langues additionnelles. Egalement appelé
Vocabulaire Electrotechnique International en ligne.
ƒ Service Clients: www.iec.ch/webstore/custserv/custserv_entry-f.htm
Si vous désirez nous donner des commentaires sur cette publication ou si vous avez des questions, visitez le FAQ du
Service clients ou contactez-nous:
Email: [e-mail]
Tél.: [phone]
Fax: [phone]
IEC 60695-6-1 ®
Edition 2.1 2010-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
BASIC SAFETY PUBLICATION
PUBLICATION FONDAMENTALE DE SÉCURITÉ
Fire hazard testing –
Part 6-1: Smoke obscuration – General guidance

Essais relatifs aux risques du feu –
Partie 6-1: Opacité des fumées – Lignes directrices générales

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CN
CODE PRIX
ICS 13.220.99; 29.020 ISBN 978-2-88912-122-9
– 2 – 60695-6-1 © IEC:2005+A1:2010

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 .16
4 General aspects of smoke test methods.17
4.1 Fire scenarios and fire models .17
4.2 Factors affecting smoke production.21
5 Principles of smoke measurement.22
5.1 Bouguer’s law.22
5.2 Extinction area.23
5.3 Log units .24
5.4 Light sources.24
5.5 Specific extinction area.24
5.6 Mass optical density .25
5.7 Visibility.26
6 Static and dynamic methods .26
6.1 Static methods.26
6.2 Dynamic methods .26
7 Test methods.28
7.1 Consideration of test methods.32
7.2 Selection of test specimen .32
8 Presentation of data.32
9 Relevance of data to hazard assessment .33

Annex A (informative) Calculation of visibility.35
Annex B (informative) Relationships between D and some other smoke parameters as
s
measured in IEC 60695-6-30 and IEC 60695-6-31 .37

Annex C (informative) Relationships between percent transmission, as measured in a
"three metre cube" enclosure, and extinction area .40

Bibliography .42

Figure 1 – Chart of Different phases in the development of a fire within a compartment .20
Figure 2 – Attenuation of light by smoke .23
Figure 3 – Extinction area .23
Figure 4 – Dynamic smoke measurement .27
Figure 5 – Evaluation and consideration of smoke test methods .34
Figure 6 – Example SPR versus t curve .31
av
Figure 7 – SMOGRA curve derived from Figure 6 .31

60695-6-1 © IEC:2005+A1:2010 – 3 –

Figure A.1 – Visibility (ω) versus extinction coefficient (k).35

Figure B.1 – Smoke parameters related to D as measured in IEC 60695-6-30 and
s
IEC 60695-6-31.39

Figure C.1 – Extinction area (amount of smoke) related to percent transmission as

measured in the "three metre cube".41

Table 1 – General classification of fires (ISO/TR 9122-1) Characteristics of fire stages

(ISO 19706) .18

Table B.1 – Conversion from D to some other smoke parameters as measured in
s
IEC 60695-6-30 and IEC 60695-6-31.38

Table C.1 – Conversions from percent transmission, as measured in the “three metre
cube” to amount of smoke (extinction area) .40

– 4 – 60695-6-1 © IEC:2005+A1:2010

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.

This consolidated version of IEC 60695-6-1 consists of the second edition (2005)
[documents 89/692/FDIS and 89/696/RVD] and its amendment 1 (2010) [documents
89/905/CDV and 89/946A/RVC]. It bears the edition number 2.1.
The technical content is therefore identical to the base edition and its amendment and
has been prepared for user convenience. A vertical line in the margin shows where the
base publication has been modified by amendment 1. Additions and deletions are
displayed in red, with deletions being struck through.

60695-6-1 © IEC:2005+A1:2010 – 5 –

International Standard IEC 60695-6-1 has been prepared by IEC technical committee 89: Fire

hazard testing.
The main changes with respect to the previous edition are listed below:

– Modified title.
– Updated normative references.

– Expanded terms and definitions.

– Numerous editorial changes of a technical nature throughout the publication.

– A flowchart has been added for the evaluation and consideration of smoke test methods.

It has the status of a basic safety publication in accordance with IEC Guide 104 and ISO/IEC
Guide 51.
This standard is to be used in conjunction with IEC 60695-6-2.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The IEC 60695-6 series, under the general heading Fire hazard testing, consists of the
following parts
Part 6-1: Smoke obscuration – General guidance
Part 6-2: Smoke obscuration – Summary and relevance of test methods
Part 6-30: Smoke obscuration – Guidance and test methods on the assessment of
obscuration hazard of vision caused by smoke opacity from electrotechnical
products involved in fires – Small scale static method - Determination of smoke
opacity - Description of the apparatus
Part 6-31: Smoke obscuration – Small-scale static test – Materials
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability date indicated on the IEC web site under "http://webstore.iec.ch"
in the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

– 6 – 60695-6-1 © IEC:2005+A1:2010

INTRODUCTION
The risk of fire needs to be considered in any electrical circuit, and the objective of component,

circuit and equipment design, as well as the choice of material, is to reduce the likelihood of

fire, even in the event of foreseeable abnormal use, malfunction or failure.

Electrotechnical products, primarily victims of a fire, may nevertheless contribute to the fire.

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 part of IEC 60695-6 serves as a guidance document and focuses on obscuration
of light by smoke.
60695-6-1 © IEC:2005+A1:2010 – 7 –

FIRE HAZARD TESTING –
Part 6-1: Smoke obscuration –
General guidance
1 Scope
This part of IEC 60695 gives guidance on:
a) optical measurement of smoke obscuration;
b) general aspects of optical smoke test methods;
c) consideration of test methods;
d) expression of smoke test data;
e) relevance of optical smoke data to hazard assessment.
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 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.
IEC 60695-1-1, Fire hazard testing – Part 1-1: Guidance for assessing the fire hazard of
electrotechnical products – General guidelines
IEC 60695-4:2001, Fire hazard testing – Part 4: Terminology concerning fire tests
IEC 60695-6-2:2001, Fire hazard testing – Part 6-2: Smoke obscuration – Summary and
relevance of test methods
IEC 60695-6-30, Fire hazard testing – Part 6: Guidance and test methods on the assessment of
obscuration hazard of vision caused by smoke opacity from electrotechnical products involved
in fires – Section 30: Small-scale static method – Determination of smoke opacity – Description
of the apparatus
IEC 60695-6-31, Fire hazard testing – Part 6-31: Smoke obscuration – Small-scale static test –
Materials
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/TR 9122-1:1989, Toxicity testing of fire effluents – Part 1: General
ISO 5659-2:1994, Plastics – Smoke generation – Part 2: Determination of optical density by a
single-chamber test
ISO/IEC 13943:2000, Fire safety – Vocabulary
ISO/IEC Guide 51:1999. Safety aspects – Guidelines for inclusion in standards

– 8 – 60695-6-1 © IEC:2005+A1:2010

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 60695-4:2005, 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 60695-6-30:1996, Fire hazard testing – Part 6: Guidance and test methods on the
assessment of obscuration hazard of vision caused by smoke opacity from electrotechnical
products involved in fires – Section 30: Small-scale static method – Determination of smoke
opacity – Description of the apparatus
IEC 60695-6-31:1999, Fire hazard testing – Part 6-31: Smoke obscuration – Small-scale static
test – Materials
IEC Guide 104:1997, The preparation of safety publications and the use of basic safety
publications and group safety publications
ISO/IEC Guide 51:1999. Safety aspects – Guidelines for inclusion in standards
ISO 5659-2:2006, Plastics – Smoke generation – Part 2: Determination of optical density by a
single-chamber test
ISO 5660-2:2002, Reaction-to-fire tests – Heat release, smoke production and mass loss rate –
Part 2: Smoke production rate (dynamic measurement)
ISO 13943:2008, Fire safety – Vocabulary
ISO 19706:2007, Guidelines for assessing the fire threat to people
NOTE ISO 9122-1:1989, Toxicity testing of fire effluents – Part 1: General, has been withdrawn and replaced by
ISO 19706:2007.
ASTM E 1354:2008, Standard Test Method for Heat and Visible Smoke Release Rates for
Materials and Products Using an Oxygen Consumption Calorimeter

EN 13823:2002, Reaction to fire tests for building products – Building products, excluding
floorings, exposed to thermal attack by a single burning item
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purpose of this document, the terms and definitions and symbols given in ISO/IEC
13943, some of which are reproduced below for the uses’ convenience, as well as the following
apply.
___________
To be published.
To be published.
60695-6-1 © IEC:2005+A1:2010 – 9 –

3.1.1
combustion
exothermic reaction of a substance with an oxidizer

NOTE Combustion generally emits effluent accompanied by flames and/or visible light.

[ISO/IEC 13943, definition 23]

3.1.2
extinction area of smoke
product of the extinction coefficient and the volume occupied by the smoke

NOTE It is a measure of the amount of smoke.

[IEC 60695-4, definition 2.130]
3.1.3
extinction coefficient of smoke
natural logarithm of the opacity of smoke divided by the path length of the light used to
measure the smoke opacity
[IEC 60695-4, definition 2.131]
3.1.4
fire
a) process of combustion characterized by the emission of heat and effluent accompanied by
smoke, and/or flame, and/or glowing;
b) rapid combustion spreading uncontrolled in time and space
[IEC 60695-4, definition 2.29]
3.1.5
fire effluent
total gaseous, particulate or aerosol effluent from combustion or pyrolysis
[IEC 60695-4, definition 2.33]
3.1.6
fire hazard
potential for injury or loss of life and/or damage to property by fire
[IEC 60695-4, definition 2.36]
3.1.7
fire model
a laboratory process, including both the apparatus and the mode of operation, intended to
simulate a certain stage of a real fire
[IEC 60695-4, definition 2.120]
3.1.8
fire scenario
detailed description of conditions, including environmental, of one or more stages from before
ignition to after completion of combustion in an actual fire at a specific location or in a real-
scale simulation
[ISO/IEC 13943, definition 58]
3.1.9
flash-over
the rapid transition to a state of total surface involvement in a fire of combustible materials
within an enclosure
– 10 – 60695-6-1 © IEC:2005+A1:2010

[IEC 60695-4, definition 2.59]

3.1.10
heat flux
amount of thermal energy emitted, transmitted or received per unit area and unit time

NOTE It is expressed in watts per square metre.

[ISO/IEC 13943, definition 85]

3.1.11
ignition
initiation of combustion
NOTE The term "ignition" in French has a very different meaning [state of body combustion].
[ISO/IEC 13943, definition 96]
3.1.12
large scale test
a test, the size of which exceeds that of a typical laboratory bench test
[IEC 60695-4, definition 2.122]
3.1.13
mass optical density of smoke
optical density multiplied by a factor, V /(L × Δm), where V is the volume of the test chamber,
Δm is the mass loss of the test specimen and L is the light path length
[IEC 60695-4, definition 2.133]
3.1.14
opacity (of smoke)
the ratio (I/T) of incident luminous flux (I) to transmitted luminous flux (T) through smoke,
under specified test conditions
[IEC 60695-4, definition 2.89]
3.1.15
optical density (of smoke) [lg(I/T)]
common logarithm of the opacity of smoke (see also specific optical density)
[IEC 60695-4, definition 2.90]

3.1.16
realscale test
a test which simulates an end-use situation in both size and surroundings
[IEC 60695-4, definition 2.123]
3.1.17
small scale test
a test which may be made on a typical laboratory bench
[IEC 60695-4, definition 2.124]
3.1.18
smoke
a visible suspension of solid and/or liquid particles in gases resulting from combustion or
pyrolysis
60695-6-1 © IEC:2005+A1:2010 – 11 –

[IEC 60695-4, definition 2.101]

3.1.19
smoke obscuration
the reduction in visibility due to smoke

[IEC 60695-4, definition 2.102]

3.1.20
smoke production rate
extinction area of smoke produced, per unit time, by the combustion of a material under

specified test conditions
3.1.21
smoke release rate
see "smoke production rate"
3.1.22
specific extinction area of smoke
extinction area of smoke divided by the mass loss of the test specimen
[IEC 60695-4, definition 2.137]
3.1.23
specific optical density (of smoke)
optical density multiplied by a geometric factor V /AL, where V is the volume of the test
chamber, A is the exposed surface area of the test specimen and L is the light path length
NOTE The use of the term ‘specific’ does not, in this case, denote 'per unit mass’ but rather denotes a
dimensionless quantity associated with a particular test apparatus and exposed surface area of the test specimen.
3.1.24
visibility
maximum distance at which an object of defined size, brightness and contrast can be seen and
recognized
3.1.1
combustion
exothermic reaction of a substance with an oxidizing agent
NOTE Combustion generally emits fire effluent accompanied by flames and/or glowing.
[ISO/IEC 13943, definition 4.46]

3.1.2
extinction area of smoke
product of the volume occupied by smoke and the extinction coefficient of the smoke
NOTE It is a measure of the amount of smoke, and the typical units are square metres (m ).
[ISO /IEC 13943, definition 4.92]
3.1.3
extinction coefficient
natural logarithm of the ratio of incident light intensity to transmitted light intensity, per unit light
path length
–1
NOTE Typical units are reciprocal metres (m ).
[ISO/IEC 13943, definition 4.93]

– 12 – 60695-6-1 © IEC:2005+A1:2010

3.1.4
fire
〈general〉 process of combustion characterized by the emission of heat and fire effluent and

usually accompanied by smoke, flame or glowing or a combination thereof

NOTE In the English language the term "fire" is used to designate three concepts, two of which, fire (3.1.5) and
fire (3.1.6), relate to specific types of self-supporting combustion with different meanings and two of them are

designated using two different terms in both French and German.

[ISO/IEC 13943, definition 4.96]

3.1.5
fire
〈controlled〉 self-supporting combustion that has been deliberately arranged to provide useful
effects and is limited in its extent in time and space
[ISO/IEC 13943, definition 4.97]
3.1.6
fire
〈uncontrolled〉 self-supporting combustion that has not been deliberately arranged to provide
useful effects and is not limited in its extent in time and space
[ISO/IEC 13943, definition 4.98]
3.1.7
fire effluent
totality of gases and aerosols, including suspended particles, created by combustion or
pyrolysis in a fire
[ISO/IEC 13943, definition 4.105]
3.1.8
fire hazard
physical object or condition with a potential for an undesirable consequence from fire
[ISO/IEC 13943, definition 4.112]
3.1.9
fire model
fire simulation
calculation method that describes a system or process related to fire development, including
fire dynamics and the effects of fire

[ISO/IEC 13943, definition 4.116]
3.1.10
fire scenario
qualitative description of the course of a fire with respect to time, identifying key events that
characterise the studied fire and differentiate it from other possible fires
NOTE It typically defines the ignition and fire growth processes, the fully developed fire stage, the fire decay
stage, and the environment and systems that impact on the course of the fire.
[ISO/IEC 13943, definition 4.129]
3.1.11
flashover
〈stage of fire〉 transition to a state of total surface involvement in a fire of combustible materials
within an enclosure
[ISO/IEC 13943, definition 4.156]

60695-6-1 © IEC:2005+A1:2010 – 13 –

3.1.12
heat flux
amount of thermal energy emitted, transmitted or received per unit area and per unit time

–2
NOTE The typical units are watts per square metre (W·m ).

[ISO/IEC 13943, definition 4.173]

3.1.13
ignition
sustained ignition (deprecated)

〈general〉 initiation of combustion
[ISO/IEC 13943, definition 4.187]
3.1.14
ignition
sustained ignition (deprecated)
〈flaming combustion〉 initiation of sustained flame
[ISO/IEC 13943, definition 4.188]
3.1.15
large-scale fire test
fire test, that cannot be carried out in a typical laboratory chamber, performed on a test
specimen of large dimensions
NOTE A fire test performed on a test specimen of which the maximum dimension is greater than 3 m is usually
called a large-scale fire test.
[ISO/IEC 13943, definition 4.205]
3.1.16
mass optical density of smoke
optical density of smoke multiplied by a factor, V /(Δm L), where V is the volume of the test
chamber, Δm is the mass lost from the test specimen, and L is the light path length
2 -1
NOTE The typical units are square metres per gram (m ⋅g ).
[ISO/IEC 13943, definition 4.225]
3.1.17
obscuration by smoke
reduction in the intensity of light due to its passage through smoke
cf. extinction area of smoke (3.1.2) and specific extinction area of smoke (3.1.26).
NOTE 1 In practice, obscuration by smoke is usually measured as the transmittance, which is normally expressed
as a percentage.
NOTE 2 Obscuration by smoke causes a reduction in visibility.
[ISO/IEC 13943, definition 4.242]

– 14 – 60695-6-1 © IEC:2005+A1:2010

3.1.18
opacity of smoke
ratio of incident light intensity to transmitted light intensity through smoke, under specified

conditions
cf. obscuration by smoke (3.1.17)

NOTE 1 Opacity of smoke is the reciprocal of transmittance.

NOTE 2 The opacity of smoke is dimensionless.

[ISO/IEC 13943, definition 4.243]

3.1.19
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
cf. specific optical density of smoke (3.1.26)
NOTE The optical density of smoke is dimensionless.
[ISO/IEC 13943, definition 4.244]
3.1.20
real-scale fire test
fire test that simulates a given application, taking into account the real scale, the real way the
item is installed and used, and the environment
NOTE Such a fire test normally assumes that the products are used in accordance with the conditions laid down
by the specifier and/or in accordance with normal practice.
[ISO/IEC 13943, definition 4.273]
3.1.21
small-scale fire test
fire test performed on a test specimen of small dimensions
NOTE A fire test performed on a test specimen of which the maximum dimension is less than 1 m is usually called
a small-scale fire test.
[ISO/IEC 13943, definition 4.292]
3.1.22
SMOGRA
smoke growth rate parameter that is a function of the rate of smoke production and the time of
smoke production
NOTE Further details are given in 6.2.4.

3.1.23
SMOGRA index
maximum value of SMOGRA during a defined test period
NOTE Further details are given in 6.2.4.
3.1.24
smoke
visible part of fire effluent
[ISO/IEC 13943, definition 4.293]

60695-6-1 © IEC:2005+A1:2010 – 15 –

3.1.25
smoke production rate
amount of smoke produced per unit time in a fire or fire test

NOTE 1 It is calculated as the product of the volumetric flow rate of smoke and the extinction coefficient of the
smoke at the point of measurement.

2 -1
NOTE 2 The typical units are square metres per second (m ⋅s ).

[ISO/IEC 13943, definition 4.295]

3.1.26
specific extinction area of smoke

extinction area of smoke produced by a test specimen in a given time period divided by the
mass lost from the test specimen in the same time period
2 -1
NOTE The typical units are square metres per gram (m ·g ).
[ISO/IEC 13943, definition 4.301]
3.1.27
specific optical density of smoke
optical density of smoke multiplied by a geometric factor
NOTE 1 The geometric factor is equal to V /(A⋅L), where V is the volume of the test chamber, A is the area of the
exposed surface of the test specimen, and L is the light path length.
NOTE 2 The use of the term “specific” does not denote “per unit mass” but rather denotes a quantity associated
with a particular test apparatus and area of the exposed surface of the test specimen.
NOTE 3 The specific optical density of smoke is dimensionless.
[ISO/IEC 13943, definition 4.303]
3.1.28
visibility
maximum distance at which an object of defined size, brightness and contrast can be seen and
recognized
[ISO/IEC 13943, definition 4.350]

– 16 – 60695-6-1 © IEC:2005+A1:2010

3.2 Symbols
Symbol Quantity Typical units
exposed area of test specimen m
A
linear decadic absorption coefficient

–1
m
D
(commonly called optical density per metre)

D ' optical density dimensionless

2 –1
D mass optical density m kg
mass
D specific optical density dimensionless
s
D (also D ) maximum specific optical density dimensionless
max m
intensity of incident light W
I
ratio of incident light to transmitted light dimensionless
I /T
linear Napierian absorption coefficient
–1
m
k
(commonly called extinction coefficient)
light path length through smoke m
L
mass loss of test specimen kg
Δm
–1
& mass loss rate kg s
m
smoke extinction area (also total smoke) m
S
smoke production rate
&
2 –1
S
(rate of change of extinction area) m s
t time s
sampling time interval s
Δt
intensity of transmitted light W
T
volume of chamber m
V
& 3 –1
volume flow rate of smoke m s
V
2 –1
σ specific extinction area m kg
f
a constant of proportionality between visibility and extinction
γ
dimensionless
coefficient
ω
visibility m
NOTE 1 The quantities based on log , i.e. D, D′, D , D and D , have similar symbols but they are
10 max mass s
different quantities and have different units.
NOTE 2 The use of the term "specific" in the case of specific optical density, D , does not denote "per unit
s
mass".
60695-6-1 © IEC:2005+A1:2010 – 17 –

4 General aspects of smoke test methods

4.1 Fire scenarios and fire models

During recent years, major advances have been made in the analysis of fire effluents. It is

recognized that the composition of the mixture of combustion products is particularly

dependent upon the nature of the combusting materials, the prevailing temperatures and

ventilation conditions, especially access of oxygen to the seat of the fire. Table 1 shows how

the different stages types of fire relate to the changing atmosphere. Conditions for use in

laboratory tests (small or large-scale) can be derived from the table in order to correspond, as
far as possible, to real-scale fires.

Fire involves a complex and interrelated array of physical and chemical phenomena. As a
result, it is difficult to simulate all aspects of a real-scale fire in a smaller scale apparatus. This
problem of fire model validity is perhaps the single most perplexing technical problem
associated with all fire testing.
General guidance for assessing the fire hazard assessment of electrotechnical products is
given in IEC 60695-1-1 60695-1-10.
After ignition, fire development may occur in different ways depending on the environmental
conditions, as well as on the physical arrangement of the combustible materials. However, a
general pattern can be established for fire development within a compartment, where the
general temperature-time curve shows three stages, plus a decay stage (see Figure 1).
Stage 1 is the incipient stage of the fire prior to sustained flaming, with little rise in the fire
room temperature. Ignition and smoke generation are the main hazards during this stage.
Stage 2 (developing fire) starts with ignition and ends with an exponential rise in the fire room
temperature. Spread of flame and heat release are the main hazards in addition to smoke
during this stage. Stage 3 (fully developed fire) starts when the surface of all of the
combustible contents of the room has decomposed to such an extent that sudden ignition
occurs all over the room, with a rapid and large increase in temperature (flash-over).
At the end of stage 3, the combustibles and/or oxygen have been largely consumed and hence
the temperature decreases at a rate which depends on the ventilation and the heat and mass
transfer characteristics of the system. This is known as decay.
In each of these stages, a different mixture of decomposition products may be formed and this,
in turn, influences the smoke density produced during that stage. Moreover, information is
required on the fire scenario being considered, in particular the conditions of incident heat flux,
oxygen availability and smoke-venting facilities.

– 18 – 60695-6-1 © IEC:2005+A1:2010

Table 1 – General classification of fires (ISO/TR 9122-1)

Oxygen * Ratio Temperature * Irradiance ***
Stages of fire 2
°C kW/m
% CO /CO **
Stage 1 Non-flaming decomposition

a) Smouldering 21 Not applicable <100 Not applicable

(self-sustaining)
b) Non-flaming (oxidative) 5 to 21 Not applicable <500 < 25

c) Non-flaming (pyrolytic) <5 Not applicable <1 000 Not applicable

Stage 2 Developing fire (flaming) 10 to 15 100 to 200 400 to 600 20 to 40

Stage 3 Fully developed fire (flaming)
a) Relatively low ventilation 1 to 5 <10 600 to 900 40 to 70
b) Relatively high ventilation 5 to 10 <100 600 to 1 200 50 to 150
*
General environmental condition (average) within compartment.
**
Mean value in fire plume near to fire.
***
Incident irradiance on to test specimen (average).

– 19 –          60695-6-1 © IEC:2005+A1:2010

Table 1 – Characteristics of fire stages (ISO 19706)

Max. temperature Oxygen
Heat flux [CO] 100×[CO2]
Fuel/air
volume %
°C
to fuel
Fire stage equivalence [CO2] ([CO2] + [CO])
surface
ratio (plume)
Fuel surface Upper layer Entrained Exhausted
kW/m
v/v % efficiency
1. Non-flaming
a) self-sustaining not
d
450 to 800 25 to 85 20 20 ⎯ 0,1 to 1 50 to 90
(smouldering) applicable
b) oxidative pyrolysis from
a b c c
⎯ 300 to 600 20 20 < 1
externally applied radiation
c) anaerobic pyrolysis from b c c
⎯ 100 to 500 0 0 >> 1
externally applied radiation
d e
2. Well-ventilated flaming 0 to 60 350 to 650 50 to 500 ≈ 20 ≈ 20 < 1 < 0,05 > 95
f
3. Under-ventilated flaming
a) small, localized fire,
a
generally in a poorly 0 to 30 300 to 600 50 to 500 15 to 20 5 to 10 0,2 to 0,4 70 to 80
> 1
ventilated compartment
g h i
b) post-flashover fire 50 to 150 350 to 650 0,1 to 0,4 70 to 90
> 600 < 15 < 5 > 1
a
The upper limit is lower than for well-ventilated flaming combustion of a given combustible.
b
The temperature in the upper layer of the fire room is most likely determined by the source of the externally applied radiation and room geometry.
c
There are few data; but for pyrolysis, this ratio is expected to vary widely depending on the material chemistry and the local ventilation and thermal conditions.
d
The fire’s oxygen consumption is small compared to that in the room or the inflow, the flame tip is below the hot gas upper layer or the upper layer is not yet
significantly vitiated to increase the CO yield significantly, the flames are not truncated by contact with another object, and the burning rate is controlled by the
availability of fuel.
e
The ratio may be up to an order of magnitude higher for materials that are fire-resistant. There is no significant increase in this ratio for equivalence ratios up
to ≈ 0,75. Between ≈ 0,75 and 1, some increase in this ratio may occur.
f
The fire’s oxygen demand is limited by the ventilation opening(s); the flames extend into the upper layer.
g
Assumed to be similar to well-ventilated flaming.
h
The plume equivalence ratio has not been measured; the use of a global equivalence ratio is inappropriate.
i
Instances of lower ratios have been measured. Generally, these result from secondary combustion outside the room vent.

– 20 – 60695-6-1 © IEC:2005+A1:2010

Stage 1 Stage 2 Stage 3
Decay stage
Non-flaming Developing fire Fully developed fire

decomposition
0 Ignition Flash-over
Time  t
IEC  603/05
Stage 3
Stage 2
Developing fire
Stage 1
Well-ventilated Decay stage
Fully developed fire
Non-flaming
flaming
Fire types 1a),
Fire type 2 Fire type 3b)
1b) and 1c)
Ignition Flash-over Time
IEC  1111/10
Figure 1 – Chart of Different phases in the development of a fire within a compartment

Compartment temperature
Compartment temperature
60695-6-1 © IEC:2005+A1:2010 – 21 –

4.2 Factors affecting smoke production

4.2.1 General
Many factors affect the production of smoke and the properties of smoke. A full description of
such properties is not possible, but the influence of several important variables is recognized.

4.2.2 Modes of decomposition
Smoke is a consequence of combustion. Combustion may be flaming or non-flaming, including

smouldering, and these different modes of combustion may produce quite different
...