ISO 7240-7:2011

INTERNATIONAL ISO
STANDARD 7240-7
Second edition
2011-08-01


Fire detection and alarm systems —
Part 7:
Point-type smoke detectors using
scattered light, transmitted light or
ionization
Systèmes de détection et d'alarme d'incendie —
Partie 7: Détecteurs de fumée ponctuels utilisant le principe de la
diffusion de la lumière, de la transmission de la lumière ou de
l'ionisation





Reference number
ISO 7240-7:2011(E)
©
ISO 2011

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ISO 7240-7:2011(E)

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©  ISO 2011
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ISO 7240-7:2011(E)
Contents Page
Foreword .v
Introduction.vii
1 Scope.1
2 Normative references.1
3 Terms and definitions .2
4 General requirements .2
4.1 Compliance .2
4.2 Response threshold value of detectors using scattered or transmitted light .2
4.3 Individual alarm indication .3
4.4 Connection of ancillary devices .3
4.5 Monitoring of detachable detectors .3
4.6 Manufacturer's adjustments.3
4.7 On-site adjustment of response behaviour .3
4.8 Protection against the ingress of foreign bodies .4
4.9 Response to slowly developing fires .4
4.10 Marking.4
4.11 Data.5
4.12 Requirements for software-controlled detectors.5
5 Tests .6
5.1 General .6
5.2 Repeatability .9
5.3 Directional dependence.10
5.4 Reproducibility .11
5.5 Variation in supply parameters.11
5.6 Air movement.12
5.7 Dazzling .13
5.8 Dry heat (operational) .13
5.9 Cold (operational).14
5.10 Damp heat, steady state (operational) .15
5.11 Damp heat, steady state (endurance).16
5.12 Sulfur dioxide (SO2) corrosion (endurance).17
5.13 Shock (operational) .18
5.14 Impact (operational) .19
5.15 Vibration, sinusoidal (operational) .20
5.16 Vibration, sinusoidal (endurance) .21
5.17 Electromagnetic compatibility (EMC) immunity tests (operational) .22
5.18 Fire sensitivity .22
6 Test report.24
Annex A (normative) Smoke tunnel for response threshold value measurements.25
Annex B (normative) Test aerosol for response threshold value measurements .26
Annex C (normative) Smoke-measuring instruments.27
Annex D (normative) Apparatus for dazzling test .31
Annex E (normative) Apparatus for impact test .32
Annex F (normative) Fire test room .34
Annex G (normative) Smouldering (pyrolysis) wood fire (TF2) .36
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ISO 7240-7:2011(E)
Annex H (normative) Glowing smouldering cotton fire (TF3) .39
Annex I (normative) Flaming plastics (polyurethane) fire (TF4).41
Annex J (normative) Flaming liquid (n-heptane) fire (TF5).43
Annex K (informative) Information concerning the construction of the smoke tunnel .45
Annex L (informative) Compensation for detector drift .47
Annex M (informative) Information concerning the construction of the measuring ionization
chamber (MIC).51
Annex N (normative) Detectors with more than one smoke sensor.53
Bibliography .55

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ISO 7240-7:2011(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.
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 7240-7 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 3, Fire detection and alarm systems.
This second edition cancels and replaces the first edition (ISO 7240-7:2003), 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: 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
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ISO 7240-7:2011(E)
⎯ 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 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 24: Sound-system loudspeakers
⎯ Part 25: Components using radio transmission paths
⎯ 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 28: Fire protection control equipment
A part 23 dealing with visual alarm devices and a part 29 dealing with video fire detectors are under
development.

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ISO 7240-7:2011(E)
Introduction
This part of ISO 7240, drawn up by ISO/TC 21/SC 3, is based on a draft prepared by the European
Committee for Standardization's CEN/TC 72, Automatic fire detection systems.
A fire detection and alarm system is required to function satisfactorily not only in the event of fire, but also
during and after exposure to conditions it is likely to meet in practice, including corrosion, vibration, direct
impact, indirect shock and electromagnetic interference. Specific tests are intended to assess the
performance of the smoke detectors under such conditions.
This part of ISO 7240 is not intended to place any other restrictions on the design and construction of such
detectors.
This edition of ISO 7240-7 introduces a requirement that smoke detectors that operate on the scattered or
transmitted light principle be marked with one of two possible nominal response threshold value bands. This
marking provides for a clearer choice of response values so that the risk of unwanted alarms can be
decreased in installations where unfavourable environmental conditions are present.
NOTE For some test fires, smoke detectors that operate on the scattered or transmitted light principle and that have
been factory set to the upper response threshold value band can fall outside one of the classification limits given in
ISO/TS 7240-9.
This edition of ISO 7240-7 introduces additional requirements for smoke detectors with more than one smoke
sensor.

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INTERNATIONAL STANDARD ISO 7240-7:2011(E)

Fire detection and alarm systems —
Part 7:
Point-type smoke detectors using scattered light, transmitted
light or ionization
1 Scope
This part of ISO 7240 specifies requirements, test methods and performance criteria for point-type smoke
detectors that operate using scattered light, transmitted light or ionization, for use in fire detection and alarm
systems installed in buildings (see ISO 7240-1). This part of ISO 7240 also covers point smoke detectors that
incorporate more than one smoke sensor operating on these principles. Additional requirements and test
methods for such detectors are given in Annex N.
For the testing of other types of smoke detectors, or smoke detectors working on different principles, this part
of ISO 7240 can be used only for guidance. Smoke detectors with special characteristics, developed for
specific risks, are not covered.
NOTE Certain types of detector contain radioactive materials. The national requirements for radiation protection differ
from country to country and are not specified in 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, Aluminium and aluminium alloys — Chemical composition
ISO 7240-1, Fire detection and alarm systems — Part 1: General and definitions
IEC 60068-1, Environmental testing — Part 1: General and guidance
IEC 60068-2-1, Environmental testing — Part 2-1: 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 2-6: Tests — Test Fc: Vibration (sinusoidal)
IEC 60068-2-27, Environmental testing — Part 2-27: Tests — Test Ea and guidance: Shock
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 50130-4:1995 + A1:1998 + A2:2003, Alarm systems — Part 4: Electromagnetic compatibility — Product
family standard: Immunity requirements for components of fire, intruder and social alarm systems
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ISO 7240-7:2011(E)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7240-1 and the following apply.
3.1
aerosol density
smoke density
number of particulates per volume as described operationally by one of two parameters:
⎯ m (3.3), an absorbance index, used in the testing of smoke detectors using scattered or transmitted light;
⎯ y (3.5), a dimensionless variable, used in the testing of smoke detectors using ionization
NOTE These parameters are not concentrations sensu stricto, but represent values which are proportional to the
concentration and have been shown to function in lieu of a true concentration value for the purposes of these tests.
3.2
least sensitive orientation
point of rotation, relative to air flow, about the vertical axis where a detector produces the maximum response
threshold value
3.3
m
absorbance index
measured light attenuation characterizing the concentration of particulates in smoke or an aerosol
NOTE The equation for m is given in Annex C.
3.4
response threshold value
A
th
〈smoke detector〉 aerosol density in the proximity of the specimen at the moment that it generates an alarm
signal, when tested as specified in 5.1.5
NOTE The response threshold value can depend on signal processing in the detector and in the control and
indicating equipment.
3.5
y
dimensionless variable, reflecting the change in the current flowing in an ionization chamber as a known
function of the concentration of particulates in the smoke or aerosol
NOTE The equation for y is given in Annex C.
4 General requirements
4.1 Compliance
In order to comply with this part of ISO 7240, the detector shall meet the requirements of this clause, which
shall be verified by visual inspection or engineering assessment, shall be tested as specified in Clause 5 (and,
for detectors with more than one smoke sensor, Annex N) and shall meet the requirements of the tests.
4.2 Response threshold value of detectors using scattered or transmitted light
Detectors using scattered or transmitted light shall conform to one of the two response threshold value bands
specified in Table 1 and the corresponding end-of-test conditions for the test fires specified in 5.18.
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ISO 7240-7:2011(E)
Table 1 — Response threshold value for detectors using scattered or transmitted light
Response threshold value in smoke tunnel Test fires end-of-test conditions
(aerosol)
TF2 TF3 TF4 TF5
dB/m
dB/m dB/m dimensionless dimensionless
1 0,05 < m < 0,3 m = 2 m = 2 y = 6 y = 6
2
0,2 < m < 0,6 m = 2 m = 2 y = 6,5 y = 7,5
NOTE The smaller the m value, the higher the sensitivity of the detectors.

4.3 Individual alarm indication
Each detector shall be provided with an integral red visual indicator by which the individual detector releasing
an alarm can be identified, until the alarm condition is reset. Where other conditions of the detector may 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 may be integral with the base or the
detector head.
NOTE The alarm condition is reset manually at the control and indicating equipment (see EN 54-2).
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,
b) 45° from the axis of the detector in at least one direction.
4.4 Connection of ancillary devices
The detector may provide for connections to ancillary devices (remote indicators, control relays, etc.), but
open- or short-circuit failures of these connections shall not prevent the correct operation of the detector.
4.5 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.
4.6 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.
4.7 On-site adjustment of response behaviour
If there is provision for on-site adjustment of the response behaviour of the detector, then
a) for all of the settings at which the manufacturer claims compliance, 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 or settings 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 this setting or these settings 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.
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ISO 7240-7:2011(E)
4.8 Protection against the ingress of foreign bodies
The detector shall be so designed that a sphere of diameter greater than (1,3 ± 0,05) mm cannot pass into the
sensor chamber or chambers.
NOTE 1 This requirement is intended to restrict the access of insects into the sensitive parts of the detector. It is known
that this requirement is not sufficient to prevent the access of all insects; however, it is considered that extreme restrictions
on the size of access holes can introduce the danger of clogging by dust, etc. It can, therefore, be necessary to take other
precautions against false alarms due to the entry of small insects.
NOTE 2 For detectors that do not have physical protection against ingress of foreign bodies, the resistance of the
detector against the adverse effect of such ingress needs to be proven by the manufacturer.
4.9 Response to slowly developing fires
The provision of “drift compensation” (e.g. to compensate for sensor drift due to the build-up of dirt in the
detector) shall not lead to a significant reduction in the sensitivity of the detector to slowly developing fires
(see Annex L).
Since it is not practical to make tests with very slow increases in smoke density, an assessment of the
response of the detector to slow increases in smoke density 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 the
following:
a) that for any rate of increase in smoke density R, which is greater than 25 % of the initial uncompensated
response threshold value of the detector, A , per hour, the time for the detector to give an alarm does
th,u
not exceed 1,6 × (A :R) by more than 100 s;
th,u
b) that the total compensation C is limited such that C < 0,6 A throughout this range, and that the fully
t t th,u
compensated response threshold value A does not exceed its initial value A by a factor greater than 1,6.
th,c th,u
4.10 Marking
Each detector shall be clearly marked with the following information:
a) reference to this part of ISO 7240 (i.e. ISO 7240-7);
b) name or trademark of the manufacturer or supplier;
c) model designation (type or number);
d) for detectors using scattered or transmitted light, the response threshold value band,
EXAMPLE   (0,05 to 0,3) dB/m or (0,2 to 0,6) dB/m.
e) wiring terminal designations;
f) 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.
For detachable detectors, the detector head shall be marked with a), b), c) and f), and the base shall be
marked with, at least, c) and e).
Where any marking on the device uses symbols or abbreviations not in common use, these should be
explained in the data supplied with the device.
The markings 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.
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ISO 7240-7:2011(E)
4.11 Data
Either detector 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 can be required by organizations certifying that detectors produced by a manufacturer
conform to the requirements of this part of ISO 7240.
4.12 Requirements for software-controlled detectors
4.12.1 General
The requirements of 4.12.2, 4.12.3 and 4.12.4 shall be met for detectors that rely on software control in order
to fulfil the requirements of this part of ISO 7240.
4.12.2 Software documentation
4.12.2.1 The manufacturer shall submit documentation that gives an overview of the software design. This
documentation shall be in sufficient detail for inspection of the design 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 structogram), including
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 those areas of memory 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.
4.12.2.2 The manufacturer shall prepare and maintain detailed design documentation. This shall be
available for inspection in a manner that respects the manufacturers' rights for confidentiality. It shall be
comprised of 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) the name of the module,
2) a description of the tasks performed,
3) a description of the interfaces, including the type of data transfer, the valid data range and the
checking for valid data;
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ISO 7240-7:2011(E)
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 recognizing the program flow;
d) details of any software tools used in the design and implementation phase (CASE-Tools, Compilers, etc.).
NOTE This detailed design documentation can be reviewed at the manufacturers' premises.
4.12.3 Software design
In order to ensure the reliability of the detector, the following requirements for software design 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.
4.12.4 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 can 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
Unless otherwise stated in a test procedure, carry out the testing after the test specimen has be
...