EN ISO 13943:2023

SLOVENSKI STANDARD
01-marec-2024
Nadomešča:
SIST EN ISO 13943:2017
Požarna varnost - Slovar (ISO 13943:2023)
Fire safety - Vocabulary (ISO 13943:2023)
Brandschutz - Vokabular (ISO 13943:2023)
Sécurité au feu - Vocabulaire (ISO 13943:2023)
Ta slovenski standard je istoveten z: EN ISO 13943:2023
ICS:
01.040.13 Okolje. Varovanje zdravja. Environment. Health
Varnost (Slovarji) protection. Safety
(Vocabularies)
13.220.01 Varstvo pred požarom na Protection against fire in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 13943
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2023
EUROPÄISCHE NORM
ICS 01.040.13; 13.220.01 Supersedes EN ISO 13943:2017
English Version
Fire safety - Vocabulary (ISO 13943:2023)
Sécurité au feu - Vocabulaire (ISO 13943:2023) Brandschutz - Vokabular (ISO 13943:2023)
This European Standard was approved by CEN on 15 March 2023.

CEN 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 CEN
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 CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13943:2023 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 13943:2023) has been prepared by Technical Committee ISO/TC 92 "Fire
safety" in collaboration with Technical Committee CEN/TC 127 “Fire safety in buildings” the secretariat
of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by March 2024, and conflicting national standards shall
be withdrawn at the latest by March 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 13943:2017.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 13943:2023 has been approved by CEN as EN ISO 13943:2023 without any modification.

INTERNATIONAL ISO
STANDARD 13943
Fourth edition
2023-09
Fire safety — Vocabulary
Sécurité au feu — Vocabulaire
Reference number
ISO 13943:2023(E)
ISO 13943:2023(E)
© ISO 2023
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 13943:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
Bibliography .59
Index .61
iii
ISO 13943:2023(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
cautioned that this may not represent the latest information, which may be obtained from the patent
database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all
such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 92, Fire safety, in collaboration with
the European Committee for Standardization (CEN) Technical Committee CEN/TC 127, Fire safety in
buildings, in accordance with the Agreement on technical cooperation between ISO and CEN (Vienna
Agreement).
This fourth edition cancels and replaces the third edition (ISO 13943:2017), which has been technically
revised.
The main changes are as follows:
— a total of 86 terms have been added or have had their definitions revised.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
ISO 13943:2023(E)
Introduction
0.1 General
Over the last two decades, there has been a significant growth in the field of fire safety. There has been
a considerable development of fire safety engineering design, especially as it relates to construction
projects, as well as the development of concepts related to performance-based design. With this
continuing evolution, there is an increasing need for agreement on a common language in the broad and
expanding area of fire safety, beyond what has traditionally been limited to the field of fire testing.
The first edition of this document, ISO 13943:2000, contained definitions of about 180 terms. However,
the areas of technology that are related to fire safety have continued to evolve rapidly and this edition
contains many new terms and their definitions, as well as revised definitions of some of the terms that
were in earlier editions.
This document defines general terms in order to establish a vocabulary applicable to fire safety,
including fire safety in buildings and civil engineering works and other elements within the built
environment. It will be updated as terms and definitions for further concepts in the field of fire safety
are agreed upon and developed.
It is important to note that some fire safety terms can have a somewhat different interpretation than
the one used in this document when used for regulations. In that case, the definition given in this
document may not apply.
The terms in this document concern:
— fundamental concepts;
— more specific concepts, such as those used specifically in fire testing or in fire safety engineering
and potentially in ISO or IEC International Standards relating to fire; and
— related concepts, such as terms used in building and civil engineering.
The layout is designed according to ISO 10241-1:2011. The terms are presented in English alphabetical
order and preferred terms are written in bold type with admitted and deprecated terms listed below
in normal type.
0.2 Use of the term “item”
For the purposes of this document, the term “item” (in French “objet”) is used to represent any single
object or assembly of objects. It may cover, for example, material, product, assembly, structure or
building, as required in the context of any individual definition.
If the “item” under consideration is a test specimen, then the term “test specimen” is used.
v
INTERNATIONAL STANDARD ISO 13943:2023(E)
Fire safety — Vocabulary
1 Scope
This document defines terminology relating to fire safety as used in ISO and IEC International
Standards.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
abnormal heat
heat that is additional to that resulting from use under normal conditions, up to and
including that which causes a fire (3.138)
3.2
absorptivity
ratio of the absorbed radiant heat flux (3.358) to the incident radiative heat flux (3.361)
Note 1 to entry: The absorptivity is dimensionless.
3.3
acceptance criteria
criteria that form the basis for assessing the acceptability of the safety of a design of a built environment
(3.36)
Note 1 to entry: The criteria can be qualitative, quantitative or a combination of both.
3.4
accuracy
closeness of the agreement between the result of a measurement and the true value of the measurand
(3.298)
[SOURCE: ASTM E176: 2021]
3.5
activation time
time interval from response by a sensing device until the suppression system (3.418), smoke (3.389)
control system, alarm system or other fire safety system is fully operational
ISO 13943:2023(E)
3.6
active fire protection
method(s) used to reduce or prevent the spread and effects of fire (3.138), heat or smoke (3.389) by
virtue of detection and/or suppression of the fire and which require a certain amount of motion and/or
response to be activated
EXAMPLE The application of agents (e.g. halon gas or water spray) to the fire or the control of ventilation
and/or smoke.
Note 1 to entry: Compare with the terms passive fire protection (3.328) and suppression system (3.418).
3.7
actual delivered density
ADD
volumetric flow rate of water per unit area that is delivered onto the top horizontal surface of a
simulated burning combustible (3.59) array
Note 1 to entry: ADD is typically determined relative to a specific heat release rate (3.230) of a fire (3.138).
1)
Note 2 to entry: ADD can be measured according to ISO 6182-7:2020.
−1
Note 3 to entry: The typical unit is mm⋅min .
3.8
acute effect
sharp or severe effect
Note 1 to entry: Compare with the term chronic effect (3.57).
Note 2 to entry: Generally used in reference to human health effects.
3.9
acute toxicity
toxicity (3.450) that causes rapidly occurring toxic (3.444) effects
Note 1 to entry: Compare with the term toxic potency (3.447).
3.10
aerosol
suspension of droplets (3.94) and/or solid particles in a gas phase which are generated by fire (3.138)
Note 1 to entry: The size of the droplets or particles typically ranges from under 10 nm to over 10 μm.
Note 2 to entry: Compare with the term droplets.
3.11
aerosol particle
individual piece of solid material that is part of the dispersed phase in an aerosol (3.10)
Note 1 to entry: There are two categories of fire (3.138) aerosol particles: unburned or partially burned particles
containing a high proportion of carbon (i.e. “soot”; 3.397), and relatively completely combusted, small particle
sized “ashes” (3.24). Soot particles of small diameter (i.e. about 1 μm) typically consist of small elementary spheres
of between 10 nm and 50 nm in diameter. Formation of soot particles is dependent on many parameters including
nucleation, agglomeration and surface growth. Oxidation (3.324) of soot particles, i.e. further combustion (3.62),
is also possible.
3.12
afterflame
flame (3.184) that persists after the ignition source (3.244) has been removed
1) Withdrawn.
ISO 13943:2023(E)
3.13
afterflame time
length of time for which an afterflame (3.12) persists under specified conditions
Note 1 to entry: Compare with the term duration of flaming (3.95).
3.14
afterglow
persistence of glowing combustion (3.221) after both removal of the ignition source (3.244) and the
cessation of any flaming combustion (3.197)
3.15
afterglow time
length of time for which an afterglow (3.14) persists under specified conditions
3.16
agent-based model
computational model for simulating the actions and interactions of autonomous agents using a set of
rules
[SOURCE: ISO 20414:2020, 3.4]
3.17
agent outlet
orifice of a piping system by means of which an extinguishing fluid can be applied towards the source
of a fire (3.138)
3.18
alarm time
time interval between ignition (3.242) of a fire (3.138) and activation of an alarm
Note 1 to entry: The time of ignition can be known, for example, in the case of a fire model (3.160) or a fire test
(3.181), or it can be assumed, for example, it can be based on an estimate working back from the time of detection.
The basis on which the time of ignition is determined is always stated when the alarm time is specified.
3.19
alight
lit, adj. CA, US
lighted
undergoing combustion (3.62)
3.20
analyte
substance that is identified or quantified in a specimen (3.400) during an analysis
3.21
arc resistance
ability of an electrically insulating material to resist the influence of an electric arc,
under specified conditions
Note 1 to entry: The arc resistance is identified by the length of the arc, the absence or presence of a conducting
path, and the burning or damage of the test specimen (3.428).
3.22
area burning rate
DEPRECATED: burning rate
DEPRECATED: rate of burning
area of material burned (3.38) per unit time under specified conditions
2 −1
Note 1 to entry: The typical unit is m ⋅s .
ISO 13943:2023(E)
3.23
arson
crime of setting a fire (3.138), usually with intent to cause damage
3.24
ash
ashes
mineral residue resulting from complete combustion (3.66)
3.25
asphyxiant
toxicant (3.449) that causes hypoxia, which can result in central nervous system depression or
cardiovascular effects
Note 1 to entry: Loss of consciousness and ultimately death can occur.
3.26
atmospheric transmissivity
ratio of the transmitted radiation (3.359) intensity after passing through unit length of a participating
medium (carbon dioxide, water vapour, dust and fog) to the radiation intensity that would have passed
the same distance through clean air
[SOURCE: ISO 24678-7:2019, 3.8]
3.27
auto-ignition
spontaneous ignition
self-ignition
unpiloted ignition
DEPRECATED: spontaneous combustion
ignition (3.242) caused by an internal exothermic reaction
Note 1 to entry: The ignition can be caused either by self-heating (3.383) or, in the case of unpiloted ignition, by
heating from an external source, as long as the external source does not include an open flame (3.184).
Note 2 to entry: In North America, “spontaneous ignition” is the preferred term used to designate ignition caused
by self-heating.
Note 3 to entry: Compare with the terms piloted ignition (3.334) and spontaneous ignition temperature (3.406).
3.28
auto-ignition temperature
DEPRECATED: self-ignition temperature
minimum temperature at which auto-ignition (3.27) is obtained in a fire test (3.180)
Note 1 to entry: The typical unit is °C.
Note 2 to entry: Compare with the term spontaneous ignition temperature (3.406).
3.29
available safe escape time
ASET
time available for escape
calculated time interval between the time of ignition (3.242) and the time at which conditions become
such that the occupant (3.321) is estimated to be incapacitated, i.e. unable to take effective action to
escape (3.114) to a safe refuge (3.376) or place of safety (3.335)
Note 1 to entry: The time of ignition can be known, for example, in the case of a fire model (3.160) or a fire test
(3.180), or it can be assumed, for example, it can be based on an estimate working back from the time of detection.
The basis on which the time of ignition is determined needs to be stated.
ISO 13943:2023(E)
Note 2 to entry: This definition equates incapacitation (3.250) with failure to escape. Other criteria for ASET are
possible. If an alternate criterion is selected, it needs to be stated.
Note 3 to entry: Each occupant may have a different value of ASET, depending on that occupant’s personal
characteristics.
3.30
backdraft
rapid flaming combustion (3.197) caused by the sudden introduction of air into a confined oxygen-
deficient space that contains hot products of incomplete combustion (3.62)
Note 1 to entry: In some cases, these conditions may result in an explosion (3.122).
3.31
behavioural scenario
description of the behaviour of occupants (3.321) during the course of a fire (3.138)
3.32
behavioural uncertainty
uncertainty (3.459) in evacuation (3.115) scenarios associated with the impact of human behaviour in
fire (3.235) during evacuation
[SOURCE: ISO 20414:2020, 3.7]
3.33
black body
form that completely absorbs any electromagnetic radiation (3.359) falling upon it
3.34
black body radiation source
ideal thermal radiation (3.437) source which completely absorbs all incident heat radiation (3.359),
whatever wavelength and direction
Note 1 to entry: The emissivity (3.103) of a black body radiation source is unity.
Note 2 to entry: A black body (3.33) can also be an ideal radiator of energy.
[SOURCE: ISO 14934-1:2010, 3.1.7, modified — original Notes 1 and 2 to entry have been removed. New
Notes 1 and 2 to entry have been added.]
3.35
building element
integral part of a built environment (3.36)
Note 1 to entry: This includes floors, walls, beams, columns, doors and penetrations, but does not include
contents.
Note 2 to entry: This definition is wider in its scope than that given in ISO 6707-1.
3.36
built environment
building or other structure
EXAMPLE Off-shore platforms, civil engineering works such as tunnels, bridges and mines, and means of
transportation such as motor vehicles and marine vessels.
Note 1 to entry: ISO 6707-1 contains a number of terms and definitions for concepts related to the built
environment.
ISO 13943:2023(E)
3.37
buoyant plume
convective updraft of fluid above a heat source
Note 1 to entry: Compare with the term fire plume (3.162).
3.38
burn, intransitive verb
undergo combustion (3.62)
3.39
burn, transitive verb
cause combustion (3.62)
3.40
burned area
that part of the damaged area (3.79) of a material that has been destroyed by combustion (3.62) or
pyrolysis (3.355), under specified conditions
Note 1 to entry: The typical unit is m .
3.41
burned length
maximum extent in a specified direction of the burned area (3.40)
Note 1 to entry: The typical unit is m.
Note 2 to entry: Compare with the term damaged length (3.80).
3.42
burning behaviour
response of a test specimen (3.428), when it burns (3.38) under specified conditions, to
examination of reaction to fire (3.364) or fire resistance (3.165)
3.43
burning debris
burning (3.38) material, other than drops, which has detached from a test specimen (3.428) during a fire
test (3.180) and continues to burn (3.38) on the floor
Note 1 to entry: Compare with the terms burning droplet (3.44), flaming debris (3.198) and flaming droplet (3.199).
3.44
burning droplet
flaming molten or flaming liquefied drop which falls from a test specimen (3.428) during a fire test
(3.181) and continues to burn (3.38) on the floor
Note 1 to entry: Compare with the terms flaming droplet (3.199), flaming debris (3.198) and burning debris (3.43).
3.45
bursting
violent rupture of an object due to an overpressure within it or upon it
3.46
bushfire
unplanned fire (3.140) in a vegetated area
Note 1 to entry: This term is used primarily, but not exclusively, in Australia, New Zealand, and Africa.
[SOURCE: ISO/TR 24188:2022, 3.1.1, modified — "as opposed to an urban area" and Notes 2 and 3 to
entry have been removed.]
ISO 13943:2023(E)
3.47
calibration
process of adjusting modelling parameters in a computational fire model (3.160) for the
purpose of improving agreement with experimental data
3.48
calibration related to fire modelling
process of adjusting modelling parameters in a computational model for the purpose of improving
agreement with experimental data
3.49
calorimeter
apparatus that measures heat
Note 1 to entry: Compare with the terms heat release rate calorimeter (3.231) and mass calorimeter (3.286).
3.50
carboxyhaemoglobin
compound formed when CO combines with haemoglobin
Note 1 to entry: Haemoglobin has an affinity for binding to CO that is approximately 245 times higher than that
for binding to oxygen. Therefore, the ability of haemoglobin to carry oxygen is seriously compromised during CO
poisoning.
3.51
carboxyhaemoglobin saturation
percentage of blood haemoglobin converted to carboxyhaemoglobin (3.50) from the reversible reaction
with inhaled carbon monoxide
3.52
ceiling jet
gas motion in a hot gas layer near a ceiling that is generated by the buoyancy of a fire plume (3.162) that
is impinging upon the ceiling
3.53
char, noun
carbonaceous residue resulting from pyrolysis (3.355) or incomplete combustion (3.62)
3.54
char, verb
form char (3.53)
3.55
char length
length of charred area
Note 1 to entry: Compare with the terms burned length (3.41) and damaged length (3.80).
Note 2 to entry: In some standards, char length is defined by a specific test method.
3.56
chimney effect
upward movement of hot fire effluent (3.147) caused by convection (3.73) currents confined within an
essentially vertical enclosure (3.106)
Note 1 to entry: This usually draws more air into the fire (3.138).
3.57
chronic effect
continuing over a long time period or recurring at low levels frequently
Note 1 to entry: Compare with the term acute effect (3.8).
ISO 13943:2023(E)
Note 2 to entry: Generally used in reference to human health effects.
3.58
clinker
solid agglomerate of residues formed by either complete combustion (3.66) or incomplete combustion
(3.62) and which can result from complete or partial melting
3.59
combustible, adj.
capable of being ignited (3.241) and burned (3.38)
3.60
combustible, noun
item capable of combustion (3.62)
3.61
combustible load
theoretical mass that would be lost from a test specimen (3.428) when it is assumed to have undergone
complete combustion (3.66) in a fire test (3.180)
3.62
combustion
exothermic reaction of a substance with an oxidizing agent (3.325)
Note 1 to entry: Combustion generally emits fire effluent (3.147) accompanied by flames (3.184) and/or glowing
(3.220).
3.63
combustion efficiency
ratio of the amount of heat release (3.229) in incomplete combustion (3.62) to the theoretical heat of
complete combustion (3.66)
Note 1 to entry: Combustion efficiency can be calculated only for cases where complete combustion can be
defined.
Note 2 to entry: Combustion efficiency is usually expressed as a percentage.
Note 3 to entry: The combustion efficiency is dimensionless.
3.64
combustion product
product of combustion
solid, liquid and gaseous material resulting from combustion (3.62)
Note 1 to entry: Combustion products can include fire effluent (3.147), ash (3.24), char (3.53), clinker (3.58) and/
or soot (3.397).
3.65
common mode failure
failure involving a single source that affects more than one type of safety system simultaneously
3.66
complete combustion
combustion (3.62) in which all the combustion products (3.64) are fully oxidized
Note 1 to entry: This means that, when the oxidizing agent (3.325) is oxygen, all carbon is converted to carbon
dioxide and all hydrogen is converted to water.
Note 2 to entry: If elements other than carbon, hydrogen and oxygen are present in the combustible (3.59)
material, those elements are converted to the most stable products in their standard states at 298 K.
ISO 13943:2023(E)
3.67
composite material
combination of two or more discrete materials
3.68
computerized model
operational computer program that implements a conceptual model (3.71)
3.69
concentration
DEPRECATED: ppm
DEPRECATED: ppm by volume
mass of a dispersed or dissolved material in a given volume
−3
Note 1 to entry: For fire effluent (3.147), the typical unit is g⋅m .
Note 2 to entry: For toxic gas (3.445), concentration is usually expressed as a volume fraction (3.473) where
3 3 −6
T = 298 K and P = 1 atm, with typical units of μl/l (= cm /m = 10 ).
Note 3 to entry: The concentration of a gas at a temperature, T, and a pressure, P, can be calculated from its
volume fraction (assuming ideal gas behaviour) by multiplying the volume fraction by the density of the gas at
that temperature and pressure.
Note 4 to entry: Pascal (Pa) is the SI unit for pressure. However, atmosphere (atm) is typically used in this context,
where 1 atm = 101,3 kPa.
Note 5 to entry: The numerical value of a concentration in ppm is identical to that for a concentration in μl/l.
3.70
concentration-time curve
plot of the concentration (3.69) of a toxic gas (3.445) or fire effluent (3.147) as a function of
time
−3
Note 1 to entry: For fire effluent, concentration is usually measured in units of g⋅m .
Note 2 to entry: For toxic gas, concentration is usually expressed as a volume fraction (3.473) where T = 298 K and
3 3 −6
P = 1 atm, with typical units of μl/l (= cm /m = 10 ).
Note 3 to entry: Pascal (Pa) is the SI unit for pressure. However, atmosphere (atm) is typically used in this context,
where 1 atm = 101,3 kPa.
3.71
conceptual model
information, mathematical modelling, data, assumptions, boundary conditions and mathematical
equations that describes the (physical) system or process of interest
3.72
controlled burn
operational strategy where the application of firefighting media such as water or foam is restricted or
avoided
Note 1 to entry: Controlled burns are often conducted to minimize damage to public health and the environment.
Other motivations for controlled burn may include limited danger of fire (3.138) spread, concerns about
firefighter safety, or limited capacity and resources at hand for firefighting operations.
Note 2 to entry: The strategy would normally be used to try and prevent water pollution by contaminated
firewater. It can also reduce air pollution due to the better combustion (3.62) and dispersion of pollutants (3.336),
but it can potentially also have adverse impacts, such as allowing or increasing the formation of hazardous and
gaseous by-products. It can also have benefits for firefighter safety and public health.
3.73
convection
transfer of heat by movement of a fluid
ISO 13943:2023(E)
3.74
convective heat flux
heat flux (3.225) caused by convection (3.73)
3.75
convective heat transfer
transfer of heat to a surface from a surrounding fluid by convection (3.73)
Note 1 to entry: The amount of heat transfer (3.233) depends on the temperature difference between the fluid
and the surface, the fluid properties, and the fluid velocity and direction.
Note 2 to entry: The fundamental modes of heat transfer are conduction or diffusion, convection and radiation
(3.359).
3.76
corrosion damage
physical and/or chemical damage or impaired function caused by chemical action
3.77
corrosion target
sensor used to determine the degree of corrosion damage (3.76), under specified conditions
Note 1 to entry: The sensor may be a product or a component. It may also be a reference material or object used
to simulate the behaviour of a product or a component.
3.78
critical fire load
fire load (3.158) required in a fire compartment (3.144) to produce a fire (3.138) of sufficient severity
to cause failure of a fire barrier(s) (3.141) or structural member(s) located within or bounding the fire
compartment
3.79
damaged area
total of those surface areas which have been affected permanently by fire (3.138) under specified
conditions
Note 1 to entry: Compare with the term burned area (3.40).
Note 2 to entry: Users of this term should specify the types of damage to be considered. This could include, for
example, loss of material, deformation, softening, melting behaviour (3.301), char (3.53) formation, combustion
(3.62), pyrolysis (3.355) or chemical attack.
Note 3 to entry: The typical unit is m .
3.80
damaged length
maximum extent in a specified direction of the damaged area (3.79)
Note 1 to entry: Compare with the terms char length (3.55) and burned length (3.41).
3.81
defend in place
life safety strategy in which occupants (3.321) are encouraged to remain in their current location rather
than to attempt escape (3.114) during a fire (3.138)
3.82
deflagration
combustion (3.62) wave propagating at subsonic velocity
Note 1 to entry: If within a gaseous medium, deflagration is the same as a flame (3.184).
ISO 13943:2023(E)
3.83
design density
measured volumetric flow rate of water from sprinklers, per unit area, that is delivered in the absence
of a fire (3.138)
−1
Note 1 to entry: The typical unit is mm⋅min .
3.84
design fire
quantitative description of assumed fire (3.138) characteristics within the design fire scenario (3.85)
Note 1 to entry: A design fire is, typically, an idealized description of the variation over time of important fire
variables such as heat release rate (3.230), flame spread rate (3.192), smoke production rate (3.393), toxic gas
(3.445) yields (3.479), and temperature.
3.85
design fire scenario
specific fire scenario (3.176) on which an analysis will be conducted
[SOURCE: ISO/TR 17252:2019, 3.2]
3.86
detection time
time interval between ignition (3.242) of a fire (3.138) and its detection by an automatic or manual
system
3.87
deterministic analysis
risk analysis approach in which the fire safety design (3.171) is evaluated using a set of worst credible
case scenarios
[SOURCE: ISO 23932-1:2018, 3.2]
3.88
deterministic model
fire model (3.160) that uses science-based mathematical expressions to produce the same result each
time the method is used with the same set of input data values
3.89
detonation
reaction characterized by a shock wave propagating at a velocity greater than the local speed of sound
in the unreacted material
3.90
diffusion flame
flame (3.184) in which combustion (3.62) occurs in a zone where the fuel (3.212) and the oxidizing agent
(3.325) mix, having been initially separate
Note 1 to entry: Compare with the term pre-mixed flame (3.344).
3.91
dioxin
family of halogenated organic compounds, the most common consisting of polychlorinated
dibenzofurans (PCDF) and polychlorinated dibenzodioxins (PCDD), although brominated dioxins and
furans are also important
Note 1 to entry: ISO 16000-14:2009 explains that this term is generally associated with polychlorinated biphenyls
(PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). There are 209
individual PCBs (congeners), 75 PCDDs and 135 PCDFs.
[SOURCE: ISO 26367-2:2017, 3.4, modified — original Notes 1 and 2 to entry have been removed. New
Note 1 to entry has been added.]
ISO 13943:2023(E)
3.92
direct flame contact
one of the three structure ignition (3.242) pathways, together with firebrands
and radiant heat
3.93
draught-free environment
space in which the results of experiments are not significantly affected by the local air speed
Note 1 to entry: A qualitative example is a space in which a wax candle flame (3.184) remains essentially
−1
undisturbed. Quantitative examples are small-scale fire tests (3.388) in which a maximum air speed of 0,1 m⋅s
−1
or 0,2 m⋅s is sometimes specified.
3.94
droplet
aerosol droplet
liquid-phase products, typically generated through pyrolysis (3.355) (reduced oxygen combustion (3.62)
conditions) from both flaming and smouldering (3.394) fires (3.138), which can condense into tarry-
like, spherically-shaped liquid beads
Note 1 to entry: Water produced from combustion can also condense around particles forming aerosol droplets.
3.95
duration of flaming
length of time for which flaming combustion (3.197) persists under specified conditions
Note 1 to entry: Compare with the term afterflame time (3.13).
3.96
ecotoxic
harmful to the environment or a specific ecosystem
[SOURCE: ISO 26367-1:2019, 3.1]
3.97
ecotoxicity
potential for biological, chemical or physical stressors to affect ecosystems
[SOURCE: ISO 26367-1:2019, 3.2]
3.98
effective concentration 50
EC
concentration (3.69) of a toxic gas (3.445) or fire effluent (3.147), statistically calculated from
concentration-response data, that causes a specified effect in 50 % of a population of a given species
within a specified exposure time (3.125) and post-exposure time (3.339)
Note 1 to entry: Compare with the term IC (3.251).
−3
Note 2 to entry: For fire effluent, the typical unit is g⋅m .
Note 3 to entry: For toxic gas, the typical unit is μl/l (T = 298 K and P = 1 atm); see volume fraction (3.473).
Note 4 to entry: The observed effect is usually a behavioural response, incapacitation (3.250), or death. The EC
for incapacitation is termed the IC . The EC for lethality is termed the LC (3.268).
50 50 50
3.99
effective exposure dose 50
Ect
product of EC (3.98) and the exposure time (3.125) over which it was determined
Note 1 to entry: Compare with the term exposure dose (3.124).
ISO 13943:2023(E)
−3
Note 2 to entry: For fire effluent (3.147), the typical unit is g⋅min⋅m .
−1
Note 3 to entry: For toxic gas (3.445), the typical unit is μl⋅min⋅l (T = 298 K and P = 1 atm); see volume fraction
(3.473).
Note 4 to entry: Ect is a measure of toxic potency (3.447).
3.100
effective heat of combustion
heat released (3.229) from a burning test specimen (3.428) in a given time interval divided by the mass
lost from the test specimen in the same time period
Note 1 to entry: Effective heat of combustion is the same as the net heat of combustion (3.313) if all the test
specimen is converted to volatile combustion products (3.64) and if all the combustion products are fully oxidized.
−1
Note 2 to entry: The typical unit is kJ⋅g .
3.101
ember
particle of solid material that emits radiant energy, due either to its temperature or to the process of
combustion (3.62) on its surface, and that poses a risk of ignition (3.242) to any materials upon which it
is incident
Note 1 to entry: Compare with the term firebrand (3.182).
3.102
emergent behaviour
behaviour which occurs due to the interactions among smaller or simpler
entities which do not exhibit such properties themselves (e.g. agents)
[SOURCE: ISO 20414:2020, 3.17, modified — delimiter "related to evacuation" has been added.]
3.103
emissivity
ratio of the radiation (3.359) emitted by a radiant source to the radiation that would be emitted by a
black body radiation source (3.34) at the same temperature
Note 1 to entry: The emissivity is dimensionless.
3.104
empirical formula
chemical formula of a substance in which the relative numbers of atoms of each type are given
Note 1 to entry: Typically, the number for one type of atom is chosen to be an integer (usually C or O). For example,
a particular sample (3.377) might be represented as C H O N Cl .
6 8,9 4,1 0,3 0,01
3.105
enclosed fire
fire (3.138) which takes place and has been ignited (3.241) inside an enclosure (3.106)
Note 1 to entry: This term is particularly important when defining the ventilation conditions in the fire.
3.106
enclosure
volume defined by bounding surfaces, which may have one or more openings
3.107
enclosure
external casing protecting the electrical and mechanical parts of apparatus
Note 1 to entry: This term excludes cables.
ISO 13943:2023(E)
3.108
end-use conditions
intended conditions to which an item will be subjected during its normal working life, when used in
accordance with the manufacturer’s instructions
3.109
engineering judgement
judgement made consistent with generally accepted scientific and engineering principles and available
relevant information
[SOURCE: ISO 8178-4:2020, 3.28, modified — preferred term has been changed from "good engineering
judgement" to "engineering judgement".]
3.110
environment
conditions and surroundings that can influence the behaviour of an item or persons when
exposed to fire (3.138)
3.111
environmental impact
significant change to the natural environment, whether adverse or beneficial, wholly or partially
resulting from a fire (3.138)
3.112
equivalence ratio
fuel (3.212)/air ratio divided by the fuel/air ratio required for a stoichiometric mixture (3.414)
Note 1 to entry: Compare with the terms fuel-lean combustion (3.214), fuel-rich combustion (3.215), stoichiometric
combustion (3.411) and stoichiometric mixture (3.414).
Note 2 to entry: Standard dry air contains 20,95 % oxygen by volume. In practice, the oxygen concentration (3.69)
in entrained air can vary and calculation of the equivalence ratio to a standard dry air basis will be required.
Note 3 to entry: The equivalent ratio is dimensionless.
3.113
error
recognizable deficiency in any phase or activity of assessment that is not due to lack of knowledge
Note 1 to entry: Error is seen not only as an error in any calculation method, but also as measurement error.
3.114
escape
effective action taken to reach a safe refuge (3.376) or place of safety (3.335)
3.115
evacuation
dispersal or removal of people from dangerous areas and their arrival at a place of relative safety
[SOURCE: ISO/TR 24188:2022, 3.1.3, modified — Note 1 to entry has been removed.]
3.116
evacuation behaviour
behaviour which enables occupants (3.321) of a building to reach a place of safety (3.335)
Note 1 to entry: Compare with the terms movement behaviour (3.309) and pre-movement behaviour (3.345).
3.117
evacuation model
model for the representation of evacuation behaviour (3.116)
ISO 13943:2023(E)
3.118
evacuation time
time interval between the time of a warning of fire (3.138) being transmitted to the occupants (3.321)
and the time at which the occupants of a specified part of a building or all of the building are able to
enter a place of safety (3.335)
Note 1 to entry: Compare with the term available safe escape time (3.29).
3.119
event tree
depiction of temporal, causal sequences of events, built around a single initiating condition
3.120
exit
designated point of departure from a building or from an enclosure (3.106)
3.121
expanded uncertainty
quantity defining an interval for the result o
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