ISO 7240-20:2010
(Main)Fire detection and alarm systems — Part 20: Aspirating smoke detectors
Fire detection and alarm systems — Part 20: Aspirating smoke detectors
ISO 7240-20:2010 specifies the requirements, test methods and performance criteria for aspirating smoke detectors for use in fire detection and alarm systems installed in buildings. Aspirating smoke detectors developed for the protection of specific risks that incorporate special characteristics (including additional features or enhanced functionality for which ISO 7240-20:2010 does not define a test or assessment method) are also covered by ISO 7240-20:2010. The performance requirements for any special characteristics are beyond the scope of ISO 7240-20:2010.
Systèmes de détection et d'alarme d'incendie — Partie 20: Détecteurs de fumée par aspiration
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 7240-20
First edition
2010-05-15
Fire detection and alarm systems —
Part 20:
Aspirating smoke detectors
Systèmes de détection et d'alarme d'incendie —
Partie 20: Détecteurs de fumée par aspiration
Reference number
ISO 7240-20:2010(E)
©
ISO 2010
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ISO 7240-20:2010(E)
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ii © ISO 2010 – All rights reserved
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ISO 7240-20:2010(E)
Contents Page
Foreword .v
Introduction.vii
1 Scope.1
2 Normative references.1
3 Terms, definitions and abbreviated terms.2
3.1 Terms and definitions .2
3.2 Abbreviated terms .2
4 Requirements.3
4.1 Compliance .3
4.2 Classification .3
4.3 Individual visual alarm indication.3
4.4 Connection of ancillary devices .3
4.5 Manufacturer's adjustments.3
4.6 On-site adjustment of response behaviour .4
4.7 Response to slowly developing fires .4
4.8 Mechanical strength of the pipework .4
4.9 Hardware components and additional sensing elements in the sampling device.5
4.10 Airflow monitoring.5
4.11 Power supply .5
4.12 Marking.6
4.13 Data.6
4.14 Additional requirements for software controlled detectors.7
5 Tests .8
5.1 General .8
5.2 Repeatability .11
5.3 Reproducibility .11
5.4 Variation in supply parameters.12
5.5 Dry heat (operational) .13
5.6 Cold (operational).14
5.7 Damp heat, steady state (operational) .15
5.8 Damp heat, steady state (endurance).16
5.9 Sulfur dioxide (SO ) corrosion (endurance).17
2
5.10 Shock (operational) .18
5.11 Impact (operational) .19
5.12 Vibration, sinusoidal (operational) .20
5.13 Vibration, sinusoidal (endurance) .21
5.14 Electromagnetic compatibility (EMC) immunity tests .22
5.15 Fire sensitivity .23
5.16 Mechanical strength of pipe.26
6 Test report.26
Annex A (informative) Apparatus for response threshold value measurements.27
Annex B (normative) Smouldering (pyrolysis) wood fire (TF2) .32
Annex C (normative) Reduced smouldering pyrolysis wood fires (TF2A and TF2B).34
Annex D (normative) Glowing smouldering cotton fire (TF3) .36
Annex E (normative) Reduced glowing smouldering cotton fire (TF3A and TF3B).38
Annex F (normative) Flaming plastics (polyurethane) fire (TF4) .40
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ISO 7240-20:2010(E)
Annex G (normative) Flaming liquid (n-heptane) fire (TF5) .42
Annex H (normative) Reduced flaming liquid (n-heptane) fire (TF5A and TF5B).43
Annex I (normative) Fire test room and ventilation system.45
Annex J (informative) Information concerning the requirements for the response to slowly
developing fires .48
Annex K (informative) Apparatus for airflow monitoring test .52
Bibliography .54
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ISO 7240-20:2010(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 7240-20 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 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
⎯ 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]
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ISO 7240-20:2010(E)
⎯ 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, is under preparation.
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ISO 7240-20:2010(E)
Introduction
This part of ISO 7240 is based on a European Standard EN 54-20:2006, prepared by the European
Committee for Standardization CEN/TC 72 “Fire detection and fire alarm systems”. It has been reviewed and
revised by ISO/TC 21/SC 3/WG 21.
Aspirating smoke detectors differ from point-type smoke detectors (see ISO 7240-7) in that air is drawn into
the smoke-sensing chamber, rather than relying on convection.
This part of ISO 7240 is not intended to place any other restriction on the design and construction of such
detectors.
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INTERNATIONAL STANDARD ISO 7240-20:2010(E)
Fire detection and alarm systems —
Part 20:
Aspirating smoke detectors
WARNING — Certain types of detectors contain radioactive materials. National requirements for
radiation protection differ from country to country and they are not, therefore, specified in this part of
ISO 7240.
1 Scope
This part of ISO 7240 specifies the requirements, test methods and performance criteria for aspirating smoke
detectors for use in fire detection and alarm systems installed in buildings.
Aspirating smoke detectors developed for the protection of specific risks that incorporate special
characteristics (including additional features or enhanced functionality for which this part of ISO 7240 does not
define a test or assessment method) are also covered by this part of ISO 7240. The performance
requirements for any special characteristics are beyond the scope of 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 7240-1, Fire detection and alarm systems — Part 1: General and definitions
ISO 7240-4, Fire detection and alarm systems — Part 4: Power supply equipment
ISO 7240-7:2003, Fire detection and fire alarm systems — Part 7: Point-type smoke detectors using scattered
light, transmitted light or ionization
EN 50130-4:1995 + Amendment 1:1998 + Amendment 2:2003, Alarm systems — Part 4: Electromagnetic
compatibility — Product family standard: Immunity requirements for components of fire, intruder and social
alarm systems
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 60068-2-75, Environmental testing — Part 2-75: Tests — Test Eh: Hammer tests
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ISO 7240-20:2010(E)
IEC 60068-2-78, Environmental testing — Part 2-78: Tests — Test Cab: Damp heat, steady state
IEC 61386-1:2008, Conduit systems for cable management — Part 1: General requirements
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7240-1 and the following apply.
3.1.1
aspirating smoke detector
smoke detector, in which air and aerosols are drawn through a sampling device and carried to one or more
smoke-sensing elements by an integral aspirator (e.g. fan or pump)
NOTE Each smoke sensing element may contain more than one sensor exposed to the same smoke sample.
3.1.2
response threshold value
measure of the aerosol concentration in the proximity of the smoke sensing element at the moment that the
specimen generates an alarm signal, when it is tested as described in 5.1.5
3.1.3
sampling device
component or series of components or a dedicated device (e.g. a pipe network, dedicated duct, probe or
hood) which forms part of the a.s.d. and transfers samples of air to the smoke sensing element(s)
NOTE The sampling device may be supplied separately.
3.1.4
sampling point
any point at which an air sample is drawn into the sampling device
3.1.5
transport time
time for aerosols to transfer from a sampling point to the smoke sensing element
3.2 Abbreviated terms
For the purposes of this document, the following abbreviations apply.
a.s.d. aspirating smoke detector
c.i.e. control and indicating equipment
c.p.c. condensation particle counter
EMC electromagnetic compatibility
MIC measuring ionization chamber
r.t.v. response threshold value
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ISO 7240-20:2010(E)
4 Requirements
4.1 Compliance
To comply with this part of ISO 7240, the detector shall meet the requirements of Clause 4, which shall be
verified by inspection and engineering assessment, and when tested in accordance with the tests described in
Clause 5, shall meet the requirements of the tests.
4.2 Classification
The manufacturer shall clearly state, in accordance with the data presented in 4.13, to which class or classes
the aspirating smoke detector is designed. To demonstrate compliance with a specific class, the aspirating
smoke detector shall be subjected to the appropriate fire sensitivity test as defined in 5.15.
NOTE Due to the differences and many variations in the design of sampling devices, aspirating smoke detectors are
generally intended for use in many varied and often rather specialized applications. Therefore, it might not be practical to
conduct type tests that define acceptance criteria for all of these applications. However, in recognition of the diversity of
application, three classes are defined to enable system designers and installers to select the most appropriate sensitivity.
Table 1 identifies the classes of detector and the corresponding fire tests used for the classification.
Table 1 — Classification of aspirating smoke detectors
Class Description Example application(s) Test fires
A Aspirating smoke detector Very early detection: the detection of very dilute smoke, for TF2A, TF3A, TF4
providing very high sensitivity example entering air conditioning ducts, to detect the and TF5A
extremely dilute concentrations of smoke that can emanate
from equipment in an environmentally controlled area such
as a clean room
B Aspirating smoke detector Early detection: for example, special fire detection within or TF2B, TF3B, TF4
providing enhanced close to particularly valuable, vulnerable or critical items and TF5B
sensitivity such as computer or electronic equipment cabinets
C Aspirating smoke detector Standard detection: general fire detection in normal rooms or TF2, TF3, TF4 and
providing normal sensitivity spaces, giving, for example, at least an equivalent level of TF5
detection as a point- or beam-type smoke detection system
4.3 Individual visual alarm indication
Each aspirating smoke detector shall be provided with integral red visual indicator(s), visible from outside the
aspirating smoke detector, by which the individual smoke-sensing element(s) (see 3.1.1) that released an
alarm can be identified until the alarm condition is reset. Where other conditions of the detector can be visually
indicated, they shall be clearly distinguishable from the alarm indication.
4.4 Connection of ancillary devices
The detector may provide for connections to ancillary devices (e.g. remote indicators, control relays). Open- or
short-circuit failures of these connections shall not prevent the correct operation of the detector.
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.
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ISO 7240-20:2010(E)
4.6 On-site adjustment of response behaviour
NOTE 1 The effective response behaviour of an aspirating smoke detector is dependent upon both the sensitivity
settings of the smoke sensing element and the design of the sampling device. Many types of aspirating smoke detectors,
therefore, have facilities to adjust the smoke-sensing element sensitivity to suit the application and sampling device, etc.
If there is provision for field-adjustment of the sensitivity of the smoke sensing element, then
a) access to the means of adjustment shall be limited by the requirement for the use of tools or a special
code;
b) it shall be possible to determine what sensitivity settings have been selected and to relate these to
documentation that describes the sensitivity settings required for different sampling devices and
applications;
NOTE 2 These adjustments may be made at the detector or at the c.i.e.
NOTE 3 Changing sensitivity settings may affect the classification of the installed a.s.d. – see 4.2.
c) if it is possible to configure the detector (including the sampling device and the sensitivity settings) in such
a way that the detector does not comply with this part of ISO 7240, it shall be clearly marked on the
detector or in the associated data that, if such configurations are used, the detector does not comply with
this part of ISO 7240.
4.7 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) and/or the provision of algorithms to match a detector to its environment shall not lead to a
significant reduction in the sensitivity of the detector to slowly developing fires.
Because it is not practical to carry out 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.
Where such algorithms are used, the detector shall be deemed to meet the requirements of 4.7 if the
documentation and assessment shows
a) how and why a sensor drifts;
b) how the compensation technique modifies the detector response to compensate for the drift;
c) that suitable limits to the compensation are in place to prevent the algorithms/means from being applied
outside the known limitations of the sensor and to ensure ongoing compliance with the provisions of this
part of ISO 7240;
d) for any rate of increase in smoke density, R, that is greater than A/4 per hour (where A is the initial
uncompensated r.t.v. of the a.s.d.), the time for the detector to give an alarm does not exceed 1,6 × A/R
by more than 100 s;
e) that the range of compensation is limited such that, throughout this range, the compensation does not
cause the r.t.v. of the detector to exceed its initial value by a factor greater than 1,6.
NOTE Further information about the assessment of requirements d) and e) is given in Annex J.
4.8 Mechanical strength of the pipework
Sampling pipes and fittings shall have adequate mechanical strength and temperature resistance.
Pipes shall either be classified in accordance with IEC 61386-1:2008 to at least class 1131 (for the
significance of the digits, see Table 2) or shall be tested in accordance with 5.16.
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ISO 7240-20:2010(E)
Table 2 — Mechanical requirements of sampling pipe
Property Class Severity
Resistance to compression 1 125 N
Resistance to impact 1 0,5 kg, 100 mm height to fall
Temperature range 31 −15 °C to +60 °C
Where the supplier of the a.s.d. does not supply pipes for the sampling device, the product documentation
shall specify that the requirements of this subclause shall be met.
4.9 Hardware components and additional sensing elements in the sampling device
Components, including optional components (box, filter, sensor, valve, etc.), in the sampling device shall be
described in the documentation. The a.s.d., including the hardware components listed (i.e. the worst-case
combination in accordance with the manufacturer's documentation), shall meet the requirements of this part of
ISO 7240.
If the component incorporates a sensing element that participates in the signal output of the a.s.d. (e.g. for
localization information), then the performance of the a.s.d., including these sensing elements, shall meet the
requirements of this part of ISO 7240.
4.10 Airflow monitoring
4.10.1 The airflow through the aspirating smoke detector shall be monitored to detect leakage or obstruction
of the sampling device or sampling point(s).
4.10.2 A fault signal shall be given when the airflow is outside the operational limits as specified by the
manufacturer's data.
A fault signal shall be given for the following:
a) when any leakage or obstruction results in an increase or decrease in the volumetric airflow of 20 % and
greater through an aspirating smoke detector; or
b) when, for aspirating smoke detectors that incorporate technology that provides for constant (or nearly
constant) volumetric flow rate, which is largely independent of the sampling device (e.g. incorporates
speed control of the fan or uses a positive displacement pump), there is a loss of 50 % or more of
sampling points.
In either case, the fault signal shall be released within not more than 300 s of the fault occurring.
NOTE This time is independent of any delay times between signalling the fault and its indication at the c.i.e. and
compensates for spurious, short-term flow variations that would otherwise result in an unwanted fault signal.
4.10.3 Where an a.s.d. has a facility to memorize the “normal” flow rate (present when the detector is
installed or serviced) and, thereafter, monitor for deviations from this normal flow, the action of setting the
memorized “normal” flow shall be a voluntary action at access level 3 (see ISO 7240-2).
4.10.4 Power cycling of the a.s.d. (turning it off and on) shall not result in a change to the memorized
“normal” flow rate.
4.11 Power supply
The power for the aspirating detector shall be supplied by power supply equipment in accordance with
ISO 7240-4. This power supply equipment may be common to the c.i.e.
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ISO 7240-20:2010(E)
4.12 Marking
Each detector shall be clearly marked with the following information:
a) number of this part of ISO 7240, e.g. “This product conforms to ISO 7240-20”;
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. a 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.
Where the sensitivity class (see 4.2) is marked on the detector, additional information shall be provided to
clearly indicate the means by which the classification of any used configuration can be determined.
This additional information may be a cross-reference to a separate document or may be a summary of the
worst-case configuration tested under each class.
Where any marking on the device uses symbols or abbreviations not in common use, these shall be explained
in the data supplied with the device.
The markings shall be visible during installation and shall be accessible during maintenance.
The markings shall not be placed on screws or other easily removable parts.
4.13 Data
Either an aspirating smoke detector shall be supplied with sufficient technical, installation and maintenance
data to enable its correct installation, sensitivity setting and operation or, if all of these data are not supplied
with each a.s.d., reference to the appropriate data sheet(s) shall be given on, or with, each aspirating smoke
detector.
The manufacturer shall declare in these data the classification of each sampling device configuration and
associated sensitivity settings. If the number of configurations is undetermined, the manufacturer shall provide
the necessary means to determine the classification of any configuration used.
These data shall also be available on the commercial datasheets to enable the correct design of an
installation prior to delivery of the hardware.
These data shall be referred to in the test report and shall be used to describe and determine the worst-case
configuration(s) that are used in
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