ISO 7240-8:2014

Fire detection and alarm systems - Part 8: Point-type fire detectors using a carbon monoxide sensor in combination with a heat sensor

ISO 7240-8:2015 specifies requirements, test methods, and performance criteria for point multi-sensor fire detectors that incorporate at least one carbon monoxide (CO) sensor in combination with one or more heat sensors, for use in fire detection and alarm systems installed in buildings (see ISO 7240‑1). For the testing of other types of CO multi-sensor fire detectors, or CO and heat multi-sensor fire detectors working on different principles, this part of ISO 7240 is only to be used for guidance. CO and heat multi-sensor fire detectors with special characteristics and developed for specific risks are not covered by this part of ISO 7240.

Systèmes de détection et d'alarme d'incendie — Partie 8: Détecteurs ponctuels utilisant un capteur de monoxide de carbone en combinaison avec un capteur de chaleur

General Information

• Status: Published
• Publication Date: 15-Dec-2014
• ICS: 13.220.20 - Fire protection
• Technical Committee: ISO/TC 21/SC 3 - Fire detection and alarm systems
• Drafting Committee: ISO/TC 21/SC 3 - Fire detection and alarm systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 09-Sep-2025
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 7240-8:2007 - Fire detection and alarm systems - Part 8: Carbon monoxide fire detectors using an electro-chemical cell in combination with a heat sensor
• Effective Date: 12-Nov-2011

Overview - ISO 7240-8:2014 (Point-type CO + heat detectors)

ISO 7240-8:2014 is an international standard for fire detection and alarm systems covering point-type multi-sensor fire detectors that combine at least one carbon monoxide (CO) sensor with one or more heat sensors. The standard specifies requirements, test methods, and performance criteria for these detectors when used in building fire detection and alarm systems (see ISO 7240‑1 for system-level requirements). It also notes that the document is for guidance when testing other CO multi-sensor types and that detectors with special characteristics developed for specific risks are excluded.

Keywords: ISO 7240-8:2014, fire detection and alarm systems, carbon monoxide sensor, CO sensor, heat sensor, multi-sensor fire detectors, point-type detectors, detector testing, performance criteria.

Key topics and technical requirements

The standard focuses on functional and environmental performance and detailed testing. Major topics include:

• General requirements and compliance - mandatory criteria for detector performance and documentation.
• Individual alarm indication - requirements for clear, local alarm signaling for each detector.
• Ancillary devices and monitoring - connection, supervision, and monitoring of detachable detectors and external devices.
• Adjustment and response behaviour - manufacturer and on-site adjustments, including rate-sensitive response settings.
• Software-controlled detectors - software design, storage of programs/data, and validation requirements.
• Measurement and test methods - procedures for measuring CO response value and heat sensor response, including:
  • Atmospheric and mounting conditions for tests
  • Operating conditions and tolerances
  • Repeatability, reproducibility, and directional dependence tests
  • Environmental endurance tests (dry heat, cold, damp heat, humidity)
  • Exposure to chemical agents (environmental concentrations and fire by-products)
  • Long-term stability, saturation, supply variation, and air movement effects
• Test reporting - required test schedules and documentation for certification.

Practical applications and users

ISO 7240-8:2014 is used by:

• Detector manufacturers for design, factory testing and certification of CO + heat multi-sensor point detectors.
• Testing laboratories and certification bodies to validate detector performance against international criteria.
• Fire safety engineers, system designers and installers specifying detectors for buildings and integrating them into fire alarm systems.
• Building owners, facility managers and regulators to inform procurement, compliance checks and risk assessments.

Practical uses include improving early detection of smoldering fires, reducing false alarms in complex environments, and demonstrating conformity for product approval and insurance purposes.

Related standards

• ISO 7240‑1 - system-level requirements for fire detection and alarm systems (see for system integration).
• Other parts of the ISO 7240 series and applicable regional/national standards (e.g., EN 54 series in Europe) may be referenced when specifying or certifying detectors for particular jurisdictions.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7240-8
Second edition
2014-12-15
Fire detection and alarm systems —
Part 8:
Point-type fire detectors using
a carbon monoxide sensor in
combination with a heat sensor
Systèmes de détection et d’alarme d’incendie —
Partie 8: Détecteurs ponctuels utilisant un capteur de monoxide de
carbone en combinaison avec un capteur de chaleur
Reference number
©
ISO 2014
© ISO 2014
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail [e-mail]
Web www.iso.org
Published in Switzerland
ii © ISO 2014 – All rights reserved

Contents Page
Foreword .vi
Introduction .viii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions and abbreviated terms . 2
3.1 Terms and definitions . 2
3.2 Abbreviated terms . 2
4 Requirements . 2
4.1 Compliance . 2
4.2 Individual alarm indication . 2
4.3 Connection of ancillary devices . 3
4.4 Monitoring of detachable detectors . 3
4.5 Manufacturer’s adjustments . 3
4.6 On-site adjustment of response behaviour . 3
4.7 Rate-sensitive response behaviour . 3
4.8 Requirements for software-controlled detectors . 4
4.8.1 General. 4
4.8.2 Software design. 4
4.8.3 The storage of programs and data . 4
5 Tests . 4
5.1 General . 4
5.1.1 Atmospheric conditions for tests. 4
5.1.2 Mounting arrangements . 4
5.1.3 Operating conditions for tests . 5
5.1.4 Tolerances . 5
5.1.5 Measurement of CO response value . 5
5.1.6 Measurement of heat sensor response value . 6
5.1.7 Provision for tests . 6
5.1.8 Test schedule . 7
5.1.9 Test report . 7
5.2 Repeatability of CO response . 7
5.2.1 Object of the test . 7
5.2.2 Test procedure . 7
5.2.3 Requirements . 7
5.3 Directional dependence of CO response . 8
5.3.1 Object of the test . 8
5.3.2 Test procedure . 8
5.3.3 Requirements . 9
5.4 Directional dependence of heat response . 9
5.4.1 Object of the test . 9
5.4.2 Test procedure . 9
5.4.3 Requirements . 9
5.5 Lower limit of heat sensitivity . 9
5.5.1 Object of the test . 9
5.5.2 Test procedure . 9
5.5.3 Requirements .10
5.6 Reproducibility of CO response .10
5.6.1 Object of the test .10
5.6.2 Test procedure .10
5.6.3 Requirements .10
5.7 Reproducibility of heat response .10
5.7.1 Object of the test .10
5.7.2 Test procedure .10
5.7.3 Requirements .11
5.8 Exposure to chemical agents at environmental concentrations .11
5.8.1 Object of the test .11
5.8.2 Test procedure .11
5.8.3 Requirements .11
5.9 Long-term stability of CO response.12
5.9.1 Object of the test .12
5.9.2 Test procedure .12
5.9.3 Requirements .12
5.10 Saturation .12
5.10.1 Object of the test .12
5.10.2 Test procedure .13
5.10.3 Requirements .13
5.11 Exposure to chemical agents which may be present during a fire .13
5.11.1 Object of the test .13
5.11.2 Test procedure .13
5.11.3 Requirements .14
5.12 Variation in supply parameters .14
5.12.1 Object of the test .14
5.12.2 Test procedure .14
5.12.3 Requirements .15
5.13 Air movement.15
5.13.1 Object of the test .15
5.13.2 Test procedure .15
5.13.3 Requirements .15
5.14 Dry heat (operational) .16
5.14.1 Object of the test .16
5.14.2 Test procedure .16
5.14.3 Requirements .16
5.15 Dry heat endurance .16
5.15.1 Object .16
5.15.2 Test procedure .17
5.15.3 Requirements .17
5.16 Cold (operational) .17
5.16.1 Object of the test .17
5.16.2 Test procedure .18
5.16.3 Requirements .18
5.17 Damp heat, cyclic (operational) .19
5.17.1 Object .19
5.17.2 Test procedure .19
5.17.3 Requirements .19
5.18 Damp heat, steady-state (endurance) .20
5.18.1 Object of the test .20
5.18.2 Test procedure .20
5.18.3 Requirements .20
5.19 Low humidity, steady-state (endurance) .21
5.19.1 Object of the test .21
5.19.2 Test procedure .21
5.19.3 Requirements .21
5.20 Sulfur dioxide SO corrosion (endurance) .22
5.20.1 Object of the test .22
5.20.2 Test procedure .22
5.20.3 Requirements .22
iv © ISO 2014 – All rights reserved

5.21 Shock (operational) .23
5.21.1 Object of the test .23
5.21.2 Test procedure .23
5.21.3 Requirements .24
5.22 Impact (operational) .24
5.22.1 Object of the test .24
5.22.2 Test procedure .24
5.22.3 Requirements .25
5.23 Vibration, sinusoidal, (operational) .25
5.23.1 Object of the test .25
5.23.2 Test procedure .25
5.23.3 Requirements .26
5.24 Vibration, sinusoidal (endurance) .26
5.24.1 Object of the test .26
5.24.2 Test procedure .26
5.24.3 Requirements .27
5.25 Electromagnetic Compatibility (EMC), Immunity tests (operational) .27
5.26 Fire sensitivity .28
5.26.1 Object of the test .28
5.26.2 Test procedure .28
6 Test report .30
7 Marking .30
8 Data .31
8.1 Hardware documentation .31
8.2 Software documentation .31
Annex A (normative) Gas test chamber for CO response value and cross
sensitivity measurements .33
Annex B (normative) Heat tunnel for response time and response temperature measurements .34
Annex C (normative) Apparatus for impact test .35
Annex D (normative) Fire test room .37
Annex E (normative) Smouldering (pyrolysis) wood fire (TF2) .39
Annex F (normative) Glowing smouldering cotton fire (TF3) .43
Annex G (normative) Open plastics (polyurethane) fire (TF4) .47
Annex H (normative) Liquid (n-heptane) fire (TF5) .50
Annex I (informative) Information concerning the construction of the gas test chamber .53
Annex J (informative) Construction of the heat tunnel .55
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 21, Equipment for fire protection and firefighting,
Subcommittee SC 3, Fire detection and alarm systems.
This second edition cancels and replaces the first edition (ISO 7240-8:2007), which has been
technically revised.
ISO 7240 consists of the following parts, under the general title Fire detection and alarm systems:
— Part 1: General and definitions
— Part 2: Control and indicating equipment
— Part 3: Audible alarm devices
— Part 4: Power supply equipment
— Part 5: Point-type heat detectors
— Part 6: Carbon monoxide fire detectors using electro-chemical cells
— Part 7: Point-type smoke detectors using scattered light, transmitted light or ionization
— Part 8: Point-type fire detectors using a carbon monoxide sensor in combination with a heat sensor
— Part 9: Test fires for fire detectors [Technical Specification]
— Part 10: Point-type flame detectors
— Part 11: Manual call points
— Part 12: Line type smoke detectors using a transmitted optical beam
— Part 13: Compatibility assessment of system components
vi © ISO 2014 – All rights reserved

— Part 14: Design, installation, commissioning and service of fire detection and fire alarm systems in and
around buildings
— Part 15: Point-type fire detectors using smoke and heat sensors
— Part 16: Sound system control and indicating equipment
— Part 17: Short-circuit isolators
— Part 18: Input/output devices
— Part 19: Design, installation, commissioning and service of sound systems for emergency purposes
— Part 20: Aspirating smoke detectors
— Part 21: Routing equipment
— Part 22: Smoke-detection equipment for ducts
— Part 23: Visual alarm devices
— Part 24: Sound-system loudspeakers
— Part 25: Components using radio transmission paths
— Part 27: Point-type fire detectors using scattered light, transmitted-light or ionization smoke sensor, an
electrochemical-cell carbon-monoxide sensor and a heat sensor
— Part 28: Fire protection control equipment
The following parts are under preparation:
— Part 29: Video fire detectors
Introduction
This part of ISO 7240 has been prepared by the Subcommittee ISO/TC 21/SC 3 and is based on
ISO 7240-8:2007.
A fire detection and fire alarm system is required to function satisfactorily not only in the event of a fire,
but also during and after exposure to conditions likely to be met in practice such as corrosion, vibration,
direct impact, indirect shock, and electromagnetic interference. Some tests specified are intended to
assess the performance of the fire detectors under such conditions.
Test Fires TF2, TF3, TF4, and TF5 from ISO/TS 7240-9 have been included to verify the detection
performance of point fire detectors using a combination of carbon monoxide and heat sensors (CO)
sensors. TF4 and TF5 specifically demonstrate the influence of the heat sensor(s). For these Test Fires,
the CO level and, where applicable, the temperature is used as test validity criteria. This part of ISO 7240
is not intended to place any other restrictions on the design and construction of such detectors.
Carbon monoxide (CO) fire detectors can react promptly to slow smouldering fires involving carbonaceous
materials. Although in the majority of fires, the products of combustion will be transported by convection,
the gaseous nature of CO means that it will also diffuse and, particularly in low energy fires, it can move
ahead of the smoke plume and, thus, provide earlier detection.
CO fire detectors alone might not react quickly to flaming fires and the addition of a heat sensor as
specified in this part of ISO 7240 provides better detection to a broader spectrum of fires.
CO fire detectors based on a combination of a CO sensor and a heat sensor might also be better suited to
applications where smoke detectors can produce unwanted alarms due to the presence of dust, steam,
or cooking vapours, etc.
While CO gas has greater mobility than smoke, it can be diluted by ventilation systems and be affected
by convection currents. Hence, the same considerations as for point smoke detectors should be taken
into account. Re-circulating systems confined to a single room have little effect on dilution, as this is
similar to the natural diffusion of the CO gas.
It is important that the location of CO fire detectors take into account areas where false operation or
non-operation is likely. Some typical locations where it is important to carefully evaluate the use of CO
fire detectors are as follows:
a) areas where CO gas can be present from exhausts and normal manufacturing processes;
EXAMPLE Car parks, car-park return air plenums, loading docks.
b) confined areas where tobacco smoking is likely.
viii © ISO 2014 – All rights reserved

INTERNATIONAL STANDARD ISO 7240-8:2014(E)
Fire detection and alarm systems —
Part 8:
Point-type fire detectors using a carbon monoxide sensor
in combination with a heat sensor
1 Scope
This part of ISO 7240 specifies requirements, test methods, and performance criteria for point multi-
sensor fire detectors that incorporate at least one carbon monoxide (CO) sensor in combination with one
or more heat sensors, for use in fire detection and alarm systems installed in buildings (see ISO 7240-1).
For the testing of other types of CO multi-sensor fire detectors, or CO and heat multi-sensor fire detectors
working on different principles, this part of ISO 7240 is only to be used for guidance. CO and heat multi-
sensor fire detectors with special characteristics and developed for specific risks are not covered by this
part of ISO 7240.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 209, Aluminium and aluminium alloys — Chemical composition
ISO 7240-1, Fire detection and alarm systems — Part 1: General and definitions
ISO 7240-5:2012, Fire detection and alarm systems — Part 5: Point-type heat detectors
IEC 60068-1, Environmental testing Part 1: General and guidance
IEC 60068-2-1, Environmental testing Part 2: Tests — Test A: Cold
IEC 60068-2-2, Environmental testing Part 2-2: Tests — Test B: Dry heat
IEC 60068-2-6, Environmental testing — Part 2: Tests — Test Fc: Vibration [sinusoidal]
IEC 60068-2-27, Basic environmental testing procedures Part 2: Tests — Test Ea and guidance: Shock
IEC 60068-2-30, Environmental testing — Part 2-30: Tests — Test Db Damp heat, cyclic (12 h+ 12 h cycle)
IEC 60068-2-42, Environmental testing — Part 2-42: Tests — Test Kc: Sulphur dioxide test for contacts
and connections
IEC 60068-2-78, Environmental testing — Part 2-78: Tests — Test Cab: Damp heat, steady state
IEC 62599-2, Alarm systems — Part 2: Electromagnetic compatibility — Immunity requirements for
components of fire and security alarm systems
3 Terms and definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms, definitions, and abbreviated terms given in ISO 7240-1
and the following apply.
3.1.1
CO response value
CO concentration in the proximity of the specimen at the moment that it generates an alarm signal, when
tested as described in 5.1.5
Note 1 to entry: The CO response value may depend on signal processing in the detector and in the fire detection
control and indicating equipment.
3.1.2
rate-sensitive
behaviour of a detector that depends on the rate of change of CO concentration
3.2 Abbreviated terms
CO carbon-monoxide
EMC electromagnetic compatibility
FDCIE fire detection control and indicating equipment
4 Requirements
4.1 Compliance
In order to comply with this part of ISO 7240, the detector shall meet the following requirements.
a) Clause 4, which shall be verified by visual inspection or engineering assessment, shall be tested as
described in Clause 5 and shall meet the requirements of the tests.
b) Clauses 7 and 8, which shall be verified by visual inspection.
4.2 Individual alarm indication
4.2.1 Each detector shall be provided with an integral red visual indicator, by which the individual
detector that released an alarm can be identified, until the alarm condition is reset. Where other conditions
of the detector might be visually indicated, these shall be clearly distinguishable from the alarm indication,
except when the detector is switched into a service mode. For detachable detectors, the indicator can be
integral with the base or the detector head.
4.2.2 The visual indicator shall be visible from a distance of 6 m in an ambient light intensity up to
500 lx at an angle of up to
a) 5° from the axis of the detector in any direction, and
b) 45° from the axis of the detector in at least one direction.
2 © ISO 2014 – All rights reserved

4.3 Connection of ancillary devices
The detector may provide for connections to ancillary devices (e.g. remote indicators, control relays,
etc.), but open- or short-circuit failures of these connections shall not prevent the correct operation of
the detector.
4.4 Monitoring of detachable detectors
For detachable detectors, a means shall be provided for a remote monitoring system (e.g. the FDCIE) to
detect the removal of the head from the base, in order to give a fault signal.
4.5 Manufacturer’s adjustments
It shall not be possible to change the manufacturer’s settings except by special means (e.g. the use of a
special code or tool) or by breaking or removing a seal.
4.6 On-site adjustment of response behaviour
4.6.1 If there is provision for on-site adjustment of the response behaviour of the detector, then the
following should be observed:
a) for all of the settings, at which the manufacturer claims compliance with this part of ISO 7240, the
detector shall comply with the requirements of this part of ISO 7240 and access to the adjustment
means shall be possible only by the use of a code or special tool or by removing the detector from its
base or mounting;
b) any setting(s) at which the manufacturer does not claim compliance with this part of ISO 7240 shall be
accessible only by the use of a code or special tool, and it shall be clearly marked on the detector or in the
associated data that if these setting(s) are used the detector does not comply with this part of ISO 7240.
4.6.2 Adjustments may be carried out at the detector or at the FDCIE.
4.7 Rate-sensitive response behaviour
4.7.1 The CO response value of the detector might depend on the rate of change of CO concentration
in the vicinity of the detector. Such behaviour may be incorporated in the detector design to improve the
discrimination between ambient CO concentrations and those generated by a fire. If such rate-sensitive
behaviour is included, then it shall not lead to a significant reduction in the sensitivity of the detector to
fires, nor shall it lead to a significant increase in the probability of unwanted alarms.
4.7.2 Since it is not practical to make tests with all possible rates of increase in CO concentration, an
assessment of the rate sensitivity of the detector shall be made by analysis of the circuit/software and/or
physical tests and simulations.
4.7.3 The detector shall be deemed to meet the requirements of this Clause, if this assessment shows
the following:
a) for any rate of increase in CO concentration less than 1 µl/l per minute, the detector will signal an
alarm condition before the CO concentration reaches 60 µl/l; and
b) the detector does not produce an alarm condition when subjected to a step change in CO concentration
of 10 µl/l, superimposed on a background concentration of between 0 µl/l and 5 µl/l.
4.8 Requirements for software-controlled detectors
4.8.1 General
The requirements of 4.8.2 and 4.8.3 shall apply to detectors that rely on software control in order to
fulfil the requirements of this part of ISO 7240.
4.8.2 Software design
In order to ensure the reliability of the detector, the following requirements for software design shall apply.
a) The software shall have a modular structure.
b) The design of the interfaces for manually and automatically generated data shall not permit invalid
data to cause error in the program operation.
c) The software shall be designed to avoid the occurrence of deadlock of the program flow.
4.8.3 The storage of programs and data
4.8.3.1 The program necessary to comply with this part of ISO 7240 and any preset data, such as
manufacturer’s settings, shall be held in non-volatile memory. Writing to areas of memory containing this
program and data shall be possible only by the use of some special tool or code and shall not be possible
during normal operation of the detector.
4.8.3.2 Site-specific data shall be held in memory that will retain data for at least two weeks without
external power to the detector, unless provision is made for the automatic renewal of such data, following
loss of power, within 1 h of power being restored.
5 Tests
5.1 General
5.1.1 Atmospheric conditions for tests
5.1.1.1 Unless otherwise stated in a test procedure, the testing shall be carried out after the test
specimen has been allowed to stabilize in the standard atmospheric conditions for testing as specified in
IEC 60068-1 as follows:
temperature:        (15 to 35) °C;
relative humidity:    (25 to 75) %;
air pressure:         (86 to 106) kPa.
5.1.1.2 The temperature and humidity shall be substantially constant for each environmental test
where the standard atmospheric conditions are applied.
5.1.2 Mounting arrangements
The specimen shall be mounted by its normal means of attachment in accordance with the manufacturer’s
instructions. If these instructions describe more than one method of mounting, then the method
considered to be most unfavourable shall be chosen for each test.
4 © ISO 2014 – All rights reserved

5.1.3 Operating conditions for tests
5.1.3.1 If a test method requires a specimen to be operational, then the specimen shall be connected to
suitable supply and monitoring equipment with characteristics as required by the manufacturer’s data.
Unless otherwise specified in the test method, the supply parameters applied to the specimen shall be set
within the manufacturer’s specified range(s) and shall remain substantially constant throughout the tests.
The value chosen for each parameter shall normally be the nominal value, or the mean of the specified
range. If a test procedure requires a specimen to be monitored to detect any alarm or fault signals, then
connections shall be made to any necessary ancillary devices (e.g. through wiring to an end-of-line device
for non-addressable detectors) to allow a fault signal to be recognized.
5.1.3.2 The details of the supply and monitoring equipment and the alarm criteria used shall be given
in the test report (see Clause 6).
5.1.4 Tolerances
5.1.4.1 Unless
...