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

ISO 7240-8:2007 specifies requirements, test methods and performance criteria for point multi-sensor fire detectors that incorporate an electrochemical cell for sensing carbon monoxide (CO) in combination with one or more heat sensors, for use in fire detection and alarm systems installed in buildings. For the testing of other types of CO multi-sensor fire detectors, or CO and heat multi-sensor fire detectors working on different principles, ISO 7240-8:2007 can be used for guidance. CO and heat multi-sensor fire detectors with special characteristics and developed for specific risks are not covered by ISO 7240-8:2007.

Systèmes de détection et d'alarme d'incendie — Partie 8: Détecteurs de monoxyde de carbone pour la détection d'incendie utilisant une cellule électrochimique en combinaison avec un capteur de chaleur

General Information

• Status: Withdrawn
• Publication Date: 12-Aug-2007
• Withdrawal Date: 12-Aug-2007
• 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: 9599 - Withdrawal of International Standard
• Start Date: 16-Dec-2014
• Completion Date: 13-Dec-2025

Relations

• Revised: 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
• Effective Date: 12-Nov-2011

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 7240-8
First edition
2007-08-15
Fire detection and alarm systems —
Part 8:
Carbon monoxide fire detectors using an
electro-chemical cell in combination
with a heat sensor
Systèmes de détection et d'alarme d'incendie —
Partie 8: Détecteurs de monoxyde de carbone pour la détection
d'incendie utilisant une cellule électrochimique en combinaison
avec un capteur de chaleur
Reference number
©
ISO 2007
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©  ISO 2007
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ii © ISO 2007 – All rights reserved

Contents Page
Foreword. v
Introduction . vii
1 Scope .1
2 Normative references .1
3 Definitions .2
4 General requirements.2
4.1 Compliance.2
4.2 Individual alarm indication .2
4.3 Connection of ancillary devices.2
4.4 Monitoring of detachable detectors.2
4.5 Manufacturer's adjustments.2
4.6 On-site adjustment of response behaviour .2
4.7 Rate-sensitive response behaviour .3
4.8 Marking .3
4.9 Data .4
4.10 Requirements for software controlled detectors .4
5 Tests.5
5.1 General.5
5.2 Repeatability of CO response.8
5.3 Directional dependence of CO response .8
5.4 Directional dependence of heat response .8
5.5 Lower limit of heat sensitivity .10
5.6 Reproducibility of CO response.10
5.7 Reproducibility of heat response.11
5.8 Exposure to chemical agents at environmental concentrations .11
5.9 Long-term stability of CO response.12
5.10 Saturation .12
5.11 Exposure to chemical agents that can be present during a fire.13
5.12 Variation in supply parameters .14
5.13 Air movement.15
5.14 Dry heat (operational).15
5.15 Cold (operational) .16
5.16 Damp heat, cyclic (operational).17
5.17 Damp heat, steady state (endurance).18
5.18 Low humidity, steady state (endurance) .19
5.19 Sulfur dioxide (SO ) corrosion (endurance).20
5.20 Shock (operational) .21
5.21 Impact (operational).22
5.22 Vibration, sinusoidal (operational).23
5.23 Vibration, sinusoidal (endurance).24
5.24 Electromagnetic compatibility (EMC), immunity tests (operational).25
5.25 Fire sensitivity.26
6 Test report .28
Annex A (normative) Gas test chamber for response threshold value and cross sensitivity
measurements.29
Annex B (normative) Heat tunnel for response time and response temperature measurements.30
Annex C (normative) Apparatus for impact test .31
Annex D (normative) Fire test room . 33
Annex E (normative) Smouldering (pyrolysis) wood fire (TF2) . 35
Annex F (normative) Glowing smouldering cotton fire (TF3) . 38
Annex G (normative) Open plastics (polyurethane) fire (TF4). 41
Annex H (normative) Liquid (heptane) fire (TF5). 43
Annex I (normative) Deep-seated smouldering cotton fire (TF9) . 45
Annex J (informative) Information concerning the construction of the gas test chamber. 47
Annex K (informative) Construction of the heat tunnel. 49

iv © ISO 2007 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 7240-8 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 3, Fire detection and alarm systems.
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 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: Carbon monoxide fire detectors using an electro-chemical cell 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
⎯ Part 14: Guidelines for drafting codes of practice for design, installation and use of fire detection and fire
alarm systems in and around buildings [Technical Report]
⎯ Part 15: Point type fire detectors using scattered light, transmitted light or ionization sensors in
combination with a heat sensor
⎯ Part 16: Sound system control and indicating equipment
⎯ Part 19: Design, installation, commissioning and service of sound systems for emergency purposes
⎯ Part 21: Routing equipment
⎯ Part 22: Smoke-detection equipment for ducts
⎯ Part 27: Point-type fire detectors using a scattered-light, transmitted-light or ionization smoke sensor, an
electrochemical-cell carbon-monoxide sensor and a heat sensor
Part 26, dealing with oil mist detectors, and Part 28, dealing with fire protection control equipment, are under
development.
vi © ISO 2007 – All rights reserved

Introduction
This part of ISO 7240 has been prepared by the Subcommittee ISO/TC 21/SC 3 and is based on both
ISO 7240-5 for heat detectors and ISO 7240-6 for carbon monoxide fire detectors.
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.
The performance of fire detectors is assessed from results obtained in specific tests; 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 are transported by convection, the
gaseous nature of CO means that it also diffuses 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 described
in this part of ISO 7240 provides better detection to a broader spectrum of fires.
CO fire detectors based on electrochemical cells might be better suited to applications where smoke detectors
can produce unwanted alarms due to the presence of dust, steam or cooking vapours, etc.
Whilst 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
a) areas where CO gas can be present from exhausts and normal manufacturing processes;
EXAMPLES Car parks, car-park return air plenums, loading docks.
b) confined areas where cigarette smoking is likely.
INTERNATIONAL STANDARD ISO 7240-8:2007(E)

Fire detection and alarm systems —
Part 8:
Carbon monoxide fire detectors using an electro-chemical cell
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 an electrochemical cell for sensing carbon monoxide (CO) 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 can 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 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.
ISO 209-1, Wrought aluminium and aluminium alloys — Chemical composition and forms of products —
Part 1: Chemical composition
ISO 7240-1, Fire detection and alarm systems — Part 1: General and definitions
ISO 7240-5:2003, Fire detection and alarm systems — Part 5: Point-type heat detectors
ISO 7240-6, Fire detection and alarm systems — Part 6: Carbon monoxide fire detectors using electro-
chemical cells
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: Tests — Test B: Dry heat
IEC 60068-2-6, Environmental testing — Part 2: Tests — Test Fc: Vibration (sinusoidal)
IEC 60068-2-27, Environmental testing — 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
EN 50130-4, Alarm Systems — Part 4: Electromagnetic compatibility — Product family standard: Immunity
requirements for components of fire, intruder and social alarm systems
3 Definitions
For the purposes of this document, the terms, definitions and symbols given in ISO 7240-1 and the following
apply.
3.1
CO response threshold value
CO concentration in the proximity of the specimen at the moment that it generates an alarm signal, when
tested in accordance with 5.1.5
NOTE The CO response threshold value may depend on signal processing in the detector and in the control and
indicating equipment.
4 General requirements
4.1 Compliance
In order to comply with this part of ISO 7240, the detector shall meet the requirements of 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.
4.2 Individual alarm indication
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
can be visually indicated, these shall be clearly distinguishable from the alarm indication, except when the
detector is switched to a service mode. For detachable detectors, the indicator may be integral with the base
or the detector head.
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.
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 control and
indicating equipment) 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
If there is provision for on-site adjustment of the response behaviour of the detector, then
2 © ISO 2007 – All rights reserved

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 means of
adjustment 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.
These adjustments may be carried out at the detector or at the control and indicating equipment.
4.7 Rate-sensitive response behaviour
The response threshold value of the detector can 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.
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.
The detector shall be deemed to meet the requirements of this subclause if this assessment shows that
a) for any rate of increase in CO concentration less than 1 µl/l/min, the detector signals 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 Marking
Each detector shall be clearly marked with the following information:
a) number of this part of ISO 7240 (i.e. ISO 7240-8);
b) name or trademark of the manufacturer or supplier;
c) model designation (type or number);
d) wiring terminal designations;
e) some mark(s) or code(s) (e.g. serial number or batch code), by which the manufacturer can identify at
least the date or batch and place of manufacture and the version number(s) of any software contained
within the detector;
f) life-expectancy of the electro-chemical cell under normal operating conditions.
For detachable detectors, the detector head shall be marked with a), b), c), e) and f), and the base shall be
marked with at least c), i.e. its own model designation, and d).
Where any marking on the device uses symbols or abbreviations not in common use, then these should be
explained in the data supplied with the device.
The marking shall be visible during installation of the detector and shall be accessible during maintenance.
The markings shall not be placed on screws or other easily removable parts.
4.9 Data
Either detectors shall be supplied with sufficient technical, installation and maintenance data to enable their
correct installation and operation or, if all of these data are not supplied with each detector, reference to the
appropriate data sheet shall be given on or with each detector.
To enable correct operation of the detectors, these data should describe the requirements for the correct
processing of the signals from the detector. This may be in the form of a full technical specification of these
signals, a reference to the appropriate signalling protocol or a reference to suitable types of control and
indicating equipment, etc.
Installation and maintenance data shall include reference to an in situ test method to ensure that detectors
operate correctly when installed.
NOTE Additional information might be required by organizations certifying that detectors produced by a manufacturer
conform to the requirements of this part of ISO 7240.
4.10 Requirements for software controlled detectors
4.10.1 General
The requirements of 4.10.2, 4.10.3 and 4.10.4 shall apply to detectors that rely on software control in order to
fulfil the requirements of this part of ISO 7240.
4.10.2 Software documentation
4.10.2.1 The manufacturer shall submit documentation that gives an overview of the software design. This
documentation shall be in sufficient detail for the design to be inspected for compliance with this part of
ISO 7240 and shall include at least the following:
a) functional description of the main program flow (e.g. as a flow diagram or schema) including the following:
1) a brief description of the modules and the functions that they perform,
2) the way in which the modules interact,
3) the overall hierarchy of the program,
4) the way in which the software interacts with the hardware of the detector,
5) the way in which the modules are called, including any interrupt processing;
b) description of which areas of memory are used for the various purposes (e.g. the program, site-specific
data and running data);
c) designation by which the software and its version can be uniquely identified.
4.10.2.2 The manufacturer shall have available detailed design documentation, which is required to be
provided only if required by the testing authority. It shall comprise at least the following:
a) overview of the whole system configuration, including all software and hardware components;
b) description of each module of the program, containing at least:
1) name of the module,
2) description of the tasks performed,
3) description of the interfaces, including the type of data transfer, the valid data range and the checking
for valid data;
4 © ISO 2007 – All rights reserved

c) full source-code listings, as hard copy or in machine-readable form (e.g. ASCII-code), including all global
and local variables, constants and labels used, and sufficient comment for the program flow to be
recognized;
d) details of any software tools used in the design and implementation phase (e.g. CASE-Tools, Compilers,
etc.).
4.10.3 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.
4.10.4 Storage of programs and data
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.
Site-specific data shall be held in memory that retains 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
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.
The temperature and humidity shall be substantially constant for each environmental test where the standard
atmospheric conditions are applied.
5.1.2 Operating conditions for tests
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 conventional
detectors) to allow a fault signal to be recognized.
The details of the supply and monitoring equipment and the alarm criteria used shall be given in the test
report; see Clause 6.
5.1.3 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.
5.1.4 Tolerances
Unless otherwise stated, the tolerances for the environmental test parameters shall be as given in the basic
reference standards for the test (e.g. the relevant part of IEC 60068).
If a specific tolerance or deviation limit is not specified in a requirement or test procedure, then a deviation
limit of ± 5 % shall be applied.
5.1.5 Measurement of CO response threshold value
5.1.5.1 Install the specimen for which the response threshold value is being measured in a gas test
chamber, as specified in Annex A, in its normal operating position, by its normal means of attachment. The
orientation of the specimen relative to the direction of gas flow shall be the least sensitive orientation as
determined in the directional dependence test (5.3), unless otherwise specified in the test procedure.
5.1.5.2 Before commencing each measurement, the gas test chamber shall be purged to ensure that the
carbon monoxide concentration is less than 1 µl/l prior to each test.
5.1.5.3 The air velocity in the proximity of the specimen shall be (0,2 ± 0,04) m/s during the
measurement, unless otherwise specified in the test procedure.
5.1.5.4 Unless otherwise specified in the test procedure, the air temperature in the gas test chamber shall
be (23 ± 5) °C and shall not vary by more than 5 K for all the measurements on a particular detector type.
5.1.5.5 Connect the specimen to its supply and monitoring equipment as specified in 5.1.2, and allow it to
stabilize for a period of at least 15 min, unless otherwise specified by the manufacturer.
5.1.5.6 For detectors whose response is rate-sensitive, the manufacturer may specify a rate of increase within
this range to ensure that the measured response threshold value is representative of the static response threshold
value of the detector. The rate of increase in CO concentration shall be similar for all measurements on a particular
detector type.
5.1.5.7 Introduce carbon monoxide gas at a rate of between 1 µl/l/min and 6 µl/l/min until the specimen
has entered an alarm state. For detectors whose response is rate-sensitive, the manufacturer may specify a
rate of increase within this range to ensure that the measured response threshold value is representative of
the static response threshold value of the detector.
To avoid an unnecessarily high level of CO, the test may be stopped when the CO concentration reaches
100 µl/l.
5.1.5.8 The rate of increase in CO concentration shall be similar for all measurements on a particular
detector type.
5.1.5.9 Record the carbon monoxide concentration at the moment the specimen gives an alarm. This
shall be taken as the CO response threshold value, S.
5.1.6 Measurement of heat sensor response value
5.1.6.1 Where detectors comply with ISO 7240-5, the response times measured in those tests may be
used as the heat-response values for the purposes of this part of ISO 7240.
6 © ISO 2007 – All rights reserved

5.1.6.2 Install the specimen for which the temperature response value is being measured in a heat
tunnel, as specified in Annex B, in its normal operating position, by its normal means of attachment. The
orientation of the specimen relative to the direction of airflow shall be the least sensitive one, as determined in
the directional dependence test (5.4), unless otherwise specified in the test procedure.
5.1.6.3 Connect the specimen to its supply and indicating equipment as specified in 5.1.2 and allow it to
stabilize for at least 15 min.
5.1.6.4 Before the test, stabilize the temperature of the air stream and the specimen to (25 ± 2) °C.
Maintain the air stream at a constant mass flow equivalent to a velocity of (0,8 ± 0,1) m/s at 25 °C.
5.1.6.5 Raise the air temperature at a rate specified in the test and measure the heat-response value as
specified in ISO 7240-5:2003, 5.1.5, until the signal specified by the manufacturer is produced by the heat
sensor.
If the detector is not capable of giving an alarm signal from heat alone, it is the responsibility of the
manufacturer to provide a special means by which the heat-response value can be measured. For example, it
may be acceptable to provide a supplementary output that varies with temperature, or specially modified
software to indicate when the air temperature has caused an internal threshold to be reached. In such cases
the special means should preferably be chosen such that the nominal heat-response value corresponds to a
response time between the minimum and maximum times given in ISO 7240-5:2003, Table 4, for a class A2
detector. It is essential that the output signal be routed through the amplification path.
5.1.6.6 Assess the heat-response value as
a) the time taken from the start of the temperature increase to the point at which the heat signal reaches a
level specified by the manufacturer, or the detector gives an alarm signal, or
b) the change in signal level produced in a certain time.
NOTE In the case of a), a shorter time represents a higher sensitivity. In the case of b) a larger change represents a
higher sensitivity.
5.1.6.7 Record the measured heat-response value as T.
5.1.7 Provision for tests
The following shall be provided for testing compliance with this part of ISO 7240:
a) for detachable detectors: 24 detector heads and bases; for non-detachable detectors: 24 specimens;
NOTE Detachable detectors comprise at least two parts; a base (socket) and a head (body). If the specimens are
detachable detectors, then the two, or more, parts together are regarded as a complete detector.
b) the data required in 4.10;
c) means to enable a quantitative measurement of the heat-response value of the temperature sensing
element(s) of the detector according to 5.1.6.
The specimens submitted shall be deemed representative of the manufacturer's normal production with
regard to their construction and calibration. This implies that the mean response threshold value of the
specimens found in the reproducibility test (5.6 and 5.7), should also represent the production mean, and that
the limits specified in the reproducibility test should also be applicable to the manufacturer's production.
5.1.8 Test schedule
The specimens shall be tested according to the following test schedule; see Table 1. After the reproducibility
test, number the four least sensitive specimens (i.e. those with the highest CO response thresholds) 21 to 24,
and number the remaining 1 to 20 arbitrarily.
5.1.9 Test report
The test results shall be reported in accordance with Clause 6.
5.2 Repeatability of CO response
5.2.1 Object of test
To show that the detector has stable behaviour with respect to its CO sensitivity, even after a number of alarm
conditions.
5.2.2 Test procedure
Measure the response threshold value of the specimen to be tested six times as specified in 5.1.5. The
orientation of the specimen relative to the direction of airflow is arbitrary, but it shall be the same for all six
measurements. Designate the maximum response threshold value as S ; the minimum value as S .
max min
5.2.3 Requirements
The lower response threshold value, S , shall be not less than 25 µl/l.
min
The ratio of the response threshold values, S : S , shall be not greater than 1,6.
max min
5.3 Directional dependence of CO response
5.3.1 Object of test
To confirm that the CO sensitivity of the detector is not unduly dependent on the direction of airflow around the
detector.
5.3.2 Test procedure
Measure the CO response threshold value of the specimen to be tested eight times as specified in 5.1.5, the
specimen being rotated 45° about its vertical axis between each measurement, so that the measurements are
taken for eight different orientations relative to the direction of airflow.
Designate the maximum response threshold value as S ; the minimum value as S .
max min
Record the least sensitive and the most sensitive orientations. The orientation for which the maximum
response threshold is measured is referred to as the least sensitive orientation, and the orientation for which
the minimum response threshold is measured is referred to as the most sensitive orientation.
5.3.3 Requirements
The lower response threshold value S shall be not less than 25 µl/l.
min
The ratio of the response threshold values, S : S , shall be not greater than 1,6.
max min
5.4 Directional dependence of heat response
5.4.1 Object of test
To confirm that the heat sensitivity of the detector is not unduly dependent on the direction of airflow around
the detector.
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Table 1 — Test schedule
Test Clause Specimen No(s)
repeatability of CO response 5.2 one chosen arbitrarily
directional dependence of CO response 5.3 one chosen arbitrarily
directional dependence of heat response 5.4 one chosen arbitrarily
lower limit of heat response 5.5 1
reproducibility of CO response 5.6 all specimens
reproducibility of heat response 5.7 all specimens
cross sensitivity 5.8 1
long-term stability of CO response 5.9 4
saturation 5.10 2
exposure to chemical agents associated with fire 5.11 3
variation in supply parameters 5.12 5
air movement 5.13 6
dry heat (operational) 5.14 7
cold (operational) 5.15 8
damp heat, cyclic (operational) 5.16 9
damp heat, steady state (endurance) 5.17 10
low humidity, steady state (endurance) 5.18 11
sulfur dioxide SO corrosion (endurance) 5.19 12
shock (operational) 5.20 13
impact (operational) 5.21 14
vibration, sinusoidal (operational) 5.22 15
vibration, sinusoidal (endurance) 5.23 15

electromagnetic compatibility (EMC) immunity tests (operational)
a
a) electrostatic discharge
a
b) radiated electromagnetic fields 17
5.24
a
c) conducted disturbances induced by electromagnetic fields 18
a
d) fast transient bursts
a
e) slow, high-energy voltage surge
fire sensitivity 5.25 21, 22, 23, 24
a
In the interests of test economy, it is permitted to use the same specimen for more than one EMC test. In that case, intermediate
functional test(s) on the specimen(s) used for more than one test may be deleted and the full functional test conducted at the end of the
sequence of tests. However it should be noted that in the event of a failure, it might not be possible to identify which test exposure

caused the failure.
5.4.2 Test procedure
Measure the heat-response value of the specimen to be tested eight times as specified in 5.1.6 at a rate of
rise of air temperature of 10 K/min, the specimen being rotated about a vertical axis by 45° between each
measurement, so that the measurements are taken for eight different orientations relative to the direction of
airflow. Stabilize the specimen at 25 °C before each measurement.
Record the heat-response value at each of the eight orientations.
Designate the maximum heat-response value as T ; the minimum value as T .
max min
Record the maximum heat-response value and the minimum heat-response value orientations. The
orientation for which the maximum response time, or the minimum change in signal level is measured is
referred to as the least sensitive heat orientation. The orientation for which the minimum response time, or the
maximum change in signal level is measured is referred to as the most sensitive heat orientation.
5.4.3 Requirements
The ratio of the heat-response values, T : T , shall not be greater than 1,3, or shall not be greater than
max min
the value for which the manufacturer can demonstrate that the resulting change in the CO response threshold
value is not more than a factor of 1,6.
5.5 Lower limit of heat sensitivity
5.5.1 Object of the test
To confirm that detectors are not more sensitive to heat alone, without the presence of CO, than is permitted
in ISO 7240-5.
5.5.2 Test procedure
Measure the heat-response value of the specimen to be tested, in its most sensitive orientation, using the
methods described in ISO 7240-5:2003, 5.3 and 5.4, but with the test being terminated when an air
temperature of 55 °C has been reached. For the purposes of these tests, the test parameters for Class A1
detectors shall be used.
NOTE It is important to limit the temperature of the detector to 55 °C to prevent possible damage to the electro-
chemical cell.
5.5.3 Requirements
In the test for static response temperature, the specimen shall not give an alarm signal at a temperature less
than 54 °C.
The specimen shall not give an alarm signal at any rate of rise of air temperature in a time less than the lower
response time limits specified in ISO 7240-5:2003, Table 4, for a Class A1 detector.
5.6 Reproducibility of CO response
5.6.1 Object of the test
To show that the sensitivity of the detector does not vary unduly from specimen to specimen and to establish
response threshold value data for comparison with the response threshold values measured after the
environmental tests.
5.6.2 Test procedure
Measure the CO response threshold value of each of the test specimens as specified in 5.1.5.
Calculate the mean of these response threshold values, which shall be designated S .
Designate the maximum response threshold value as S ; the minimum value as S .
max min
10 © ISO 2007 – All rights reserved

5.6.3 Requirements
The lower response threshold value, S , shall be not less than 25 µl/l.
min
The ratio of the response threshold values, S : S, shall not be greater than 1,33, and the ratio of the CO
max
response threshold values, S : S , shall not be greater than 1.5.
min
5.7 Reproducibility of heat response
5.7.1 Object of the test
To show that the heat sensitivity of the detector does not vary unduly from specimen to specimen and to
establish heat-response value data for comparison with the heat-response values measured after the
environmental tests.
5.7.2 Test procedure
Measure the heat-response value of each of the test specimens as specified in 5.1.6 at a rate of rise of air
temperature of 20 K/min and record the heat-response value.
Designate the maximum heat-response value as T ; the minimum value as T .
max min
5.7.3 Requirements
The rati
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