EN 54-20:2006

SLOVENSKI STANDARD
01-november-2006
Sistemi za odkrivanje in javljanje požara ter alarmiranje - 20. del: Aspiracijski dimni
javljalniki
Fire detection and fire alarm systems - Part 20: Aspirating smoke detectors
Brandmeldeanlagen - Teil 20: Ansaugrauchmelder
Systemes de détection et d'alarme incendie - Partie 20 : Détecteurs de fumée par
aspiration
Ta slovenski standard je istoveten z: EN 54-20:2006
ICS:
13.220.20 3RåDUQD]DãþLWD Fire protection
13.320 Alarmni in opozorilni sistemi Alarm and warning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN 54-20
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2006
ICS 13.220.20
English Version
Fire detection and fire alarm systems - Part 20: Aspirating
smoke detectors
Systèmes de détection et d'alarme incendie - Partie 20 : Brandmeldeanlagen - Teil 20: Ansaugrauchmelder
Détecteurs de fumée par aspiration
This European Standard was approved by CEN on 18 May 2006.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 54-20:2006: E
worldwide for CEN national Members.

Contents Page
Foreword. 4
1 Scope. 6
2 Normative references . 6
3 Terms and definitions. 7
4 Symbols and abbreviations . 7
5 Requirements . 8
5.1 Compliance. 8
5.2 Individual visual alarm indication . 8
5.3 Connection of ancillary devices . 8
5.4 Manufacturer's adjustments . 8
5.5 On site adjustment of response behaviour.8
5.6 Response to slowly developing fires. 9
5.7 Mechanical strength of the pipework. 9
5.8 Hardware components and additional sensing elements in the sampling device . 10
5.9 Airflow monitoring . 10
5.10 Power supply. 11
5.11 Data. 11
5.12 Additional requirements for software controlled detectors . 12
6 Tests. 13
6.1 General. 13
6.2 Repeatability. 16
6.3 Reproducibility. 17
6.4 Variation in supply parameters . 17
6.5 Dry heat (operational). 18
6.6 Cold (operational) . 19
6.7 Damp heat, steady state (operational). 20
6.8 Damp heat, steady state (endurance) . 21
6.9 Sulfer dioxide (SO ) corrosion (endurance). 22
6.10 Shock (operational). 23
6.11 Impact (operational). 24
6.12 Vibration, sinusoidal (operational). 25
6.13 Vibration, sinusoidal (endurance). 26
6.14 Electromagnetic compatibility (EMC) immunity tests. 27
6.15 Fire sensitivity. 28
7 Classification and designation. 31
8 Marking . 32
Annex A (informative) Apparatus for Response Threshold Value (RTV) measurements . 33
Annex B (normative) Smouldering (pyrolysis) wood fire (TF2). 41
B.1 Fuel. 41
B.2 Hotplate. 41
B.3 Arrangement. 41
B.4 Heating rate . 42
B.5 End of test condition . 42
B.6 Test validity criteria . 42
Annex C (normative) Reduced smouldering pyrolysis wood fires (TF2A and TF2B). 44
C.1 Fuel. 44
C.2 Hotplate. 44
C.3 Arrangement. 44
C.4 Heating rate . 45
C.5 End of test condition . 45
C.6 Test validity criteria . 45
Annex D (normative) Glowing smouldering cotton fire (TF3) . 47
D.1 Fuel. 47
D.2 Arrangement. 47
D.3 Ignition . 48
D.4 End of test condition . 48
D.5 Test validity criteria . 48
Annex E (normative) Reduced glowing smouldering cotton fire (TF3A and TF3B). 50
E.1 Fuel. 50
E.2 Arrangement. 50
E.3 Ignition . 51
E.4 End of test condition . 51
E.5 Test validity criteria . 52
Annex F (normative) Flaming plastics (polyurethane) fire (TF4) . 53
F.1 Fuel. 53
F.2 Arrangement. 53
F.3 Ignition . 53
F.4 End of test condition . 53
F.5 Test validity criteria . 53
Annex G (normative) Flaming liquid (n-heptane) fire (TF5). 55
G.1 Fuel. 55
G.2 Arrangement. 55
G.3 Ignition . 55
G.4 End of test condition . 55
G.5 Test validity criteria . 55
Annex H (normative) Reduced flaming liquid (n-heptane) fire (TF5A and TF5B). 57
H.1 Fuel. 57
H.2 Arrangement. 57
H.3 Ignition . 57
H.4 End of test condition . 58
H.5 Test validity criteria . 58
Annex I (normative) Fire test room and ventilation system . 60
I.1 Fire test room . 60
I.2 Ventilation system . 62
Annex J (informative) Information concerning the requirements for the response to
slowly developing fires. 64
Annex K (informative) Apparatus for air flow monitoring test.68
K.1 General. 68
K.2 Airflow measuring with worst-case sampling device . 68
K.3 Airflow monitoring test with test pipe network. 69
Annex ZA (informative) Clauses of this European Standard addressing the provisions of
the EU Construction Products Directive .71
ZA.1 Scope and relevant clauses. 71
ZA.2 Procedures for the attestation of conformity of aspirating smoke detectors
covered by this standard . 72
ZA.3 CE Marking and labelling and accompanying documentation . 77
ZA.4 EC certificate and declaration of conformity . 78
Bibliography . 80

Foreword
This document (EN 54-20:2006) has been prepared by Technical Committee CEN/TC 72 “Fire
detection and fire alarm systems”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2006, and conflicting national standards
shall be withdrawn at the latest by June 2009.
This document has been prepared under a mandate given to CEN by the European Commission and
the European Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with EU Directive(s), see informative Annex ZA, which is an integral part of this
document.
EN 54 “Fire detection and fire alarm systems” consists of the following parts:
Part 1: Introduction
Part 2: Control and indicating equipment
Part 3: Fire alarm devices – Sounders
Part 4: Power supply equipment
Part 5: Heat detectors - Point detectors
Part 7: Smoke detectors - Point detectors using scattered light, transmitted light or ionization
Part 10: Flame detectors - Point detectors
Part 11: Manual call points
Part 12: Smoke detectors - Line detectors using an optical light beam
Part 13: Compatibility assessment of system components
Part 14: Guidelines for planning, design, installation, commissioning, use and maintenance
Part 15: Point detectors using a combination of detected fire phenomena
Part 16: Voice alarm control and indicating equipment
Part 17: Short-circuit isolators
Part 18: Input/output devices
Part 20: Aspirating smoke detectors
Part 21: Alarm transmission and fault warning routing equipment
Part 22: Line-type heat detectors
Part 23: Fire alarm devices - Visual alarms
Part 24: Components of voice alarm systems – Loudspeakers
Part 25: Components using radio links and system requirements
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
1 Scope
This European Standard specifies the requirements, test methods and performance criteria for
aspirating smoke detectors for use in fire detection and fire 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 standard does
not define a test or assessment method) are not covered by this standard. The performance
requirements for any special characteristics are beyond the scope of this standard.
NOTE Certain types of detector contain radioactive materials. The national requirements for radiation
protection differ from country to country and they are not therefore specified in this standard.
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.
EN 54-1:1996, Fire detection and fire alarm systems – Part 1: Introduction
EN 54-2, Fire detection and fire alarm systems – Part 2: Control and indicating equipment
EN 54-4, Fire detection and fire alarm systems – Part 4: Power supply equipment
EN 54-7:2000, Fire detection and fire alarm systems – Part 7: Smoke detectors – Point detectors
using scattered light, transmitted light or ionization
EN 50130-4:1995, Alarm systems – Part 4: Electromagnetic compatibility – Product family standard:
Immunity requirements for components of fire, intruder and social alarm systems
EN 60068-1, Environmental testing - Part 1: General and guidance (IEC 60068-1:1988 + Corrigendum
1988 + A1:1992)
EN 60068-2-1, Environmental testing; part 2: tests; tests A: cold (IEC 60068-2-1:1990)
EN 60068-2-2, Basic environmental testing procedures; part 2: tests; tests B: dry heat (IEC 60068-2-
2:1974 + IEC 60068-2-2A:1976)
EN 60068-2-6, Environmental testing - Part 2: Tests - Tests Fc: Vibration (sinusoidal) (IEC 60068-2-
6:1995 + Corrigendum 1995)
EN 60068-2-27, Basic environmental testing procedures – Part 2: Tests – Test Ea and guidance:
Shock (IEC 60068-2-27:1987)
EN 60068-2-42, Environmental testing - Part 2-42: Tests; Test Kc: Sulphur dioxide test for contacts
and connections (IEC 60068-2-42:2003)
EN 60068-2-75, Environmental testing - Part 2: Tests - Test Eh: Hammer tests (IEC 60068-2-75:1997)
EN 60068-2-78, Environmental testing - Part 2-78: Tests; Test Cab: Damp heat, steady state (IEC
60068-2-78:2001)
EN 61386-1:2004, Conduit systems for electrical installations - Part 1: General requirements (IEC
61386-1:1996 + A1:2000)
3 Terms and definitions
For the purposes of this document the terms and definitions given in EN 54-1:1996 and the following
apply.
3.1
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.
3.2
sampling device
component or series of components or dedicated device (e.g. a pipe network, dedicated duct, probe
or hood) which forms part of the ASD and transfers samples of air to the smoke sensing element(s)
NOTE The sampling device may be supplied separately.
3.3
sampling point
any point at which an air sample is drawn into the sampling device
3.4
response threshold value (RTV)
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 6.1.5
3.5
transport time
time for aerosols to transfer from a sampling point to the smoke sensing element
3.6
recovery
treatment of a specimen, after conditioning, so that the properties of the specimen may be stabilized
before measurement of the said property as required by this standard
4 Symbols and abbreviations
For the purposes of this standard, the following abbreviations apply:
ASD: Aspirating smoke detector.
CIE: Control and indicating equipment.
CPC: Condensation particle counter.
DUT: Detector under test.
EEA: European Economic Area.
EMC: Electromagnetic compatibility.
EOT: End of test.
FPC: Factory production control.
MIC: Measuring ionization chamber.
RTV: Response threshold value.
5 Requirements
5.1 Compliance
To comply with this standard the detector shall meet the requirements of this clause, which shall be
verified by inspection and engineering assessment, and, when tested in accordance with the tests
described in Clause 6, shall meet the requirements of the tests.
5.2 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),
which released an alarm, can be identified, until the alarm condition is reset. Where other conditions
of the detector may be visually indicated, they shall be clearly distinguishable from the alarm
indication.
5.3 Connection of ancillary devices
The detector may provide for connections to ancillary devices (e.g. remote indicators, control relays),
but open- or short-circuit failures of these connections shall not prevent the correct operation of the
detector.
5.4 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.
5.5 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 need 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 which describes the sensitivity settings required for different sampling devices
and applications;
NOTE 2 These adjustments may be made at the detector or at the control and indicating equipment.
NOTE 3 Changing sensitivity settings may affect the classification of the installed ASD – see Clause 7.
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 standard, 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 standard.
5.6 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 detector's sensitivity to slowly developing fires.
Because it is not practical to make tests with very slow increases in smoke density, an assessment of
the detector's response 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 this sub-
clause 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 being
applied outside the known limitations of the sensor and to ensure ongoing compliance with the
clauses of this standard,
d) for any rate of increase in smoke density R, which is greater than A/4 per hour (where A is the
detector's initial uncompensated response threshold value), the time for the detector to give an
alarm does not exceed 1,6 × A/R by more than 100 s,
e) the range of compensation is limited such that, throughout this range, the compensation does not
cause the response threshold value 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.
5.7 Mechanical strength of the pipework
The sampling pipes and fittings shall have adequate mechanical strength and temperature resistance.
The minimum requirement shall be:
To use pipes classified in accordance with EN 61386-1 to at least Class 1131 (for the first four digits,
see Table 1).
Table 1 — 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

Pipes which are not so classified by the manufacturer of the pipe shall either be tested in accordance
with Table 2 for the classes in Table 1, or the ASD manufacturer shall provide evidence that the
requirements of this sub-clause are met.
Table 2 — Mechanical tests
Test EN 61386-1:2004, subclause
Compression test 10.2
Impact test 10.3
Resistance to heat 12.2
The impact test shall be conducted at the minimum of the temperature range (i.e. -15 °C).
The pipe is deemed to have passed the resistance to heat test if any crushing of the pipe does not
reduce the internal diameter to less than 80 % of its original value.
Where the supplier of the ASD does not supply pipe for the sampling device, the product
documentation shall specify that the requirements of this sub-clause shall be met.
NOTE An example of suitable evidence that the pipe meets this requirement is a test report, approval
certificate or a declaration of conformity from the manufacturers of the pipe, even though it is not marked in
accordance with EN 61386-1.
5.8 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 ASD, including the hardware components listed (i.e. the
worst case combination in accordance with the manufacturer's documentation), shall meet the
requirements of this standard.
If the component incorporates a sensing element which participates in the signal output of the ASD
(e.g. for localisation information) then the performance of the ASD, including these sensing elements,
shall meet the requirements of this standard.
5.9 Airflow monitoring
5.9.1 A fault signal shall be given when the airflow is outside the operational limits as specified by
the manufacturer in his data.
5.9.2 The airflow through the aspirating smoke detector shall be monitored to detect leakage or
obstruction of the sampling device or sampling point(s).
Either a fault signal shall be given when any leakage or obstruction results in an increase or decrease
in the volumetric airflow of 20 % and greater through the aspirating smoke detector, or where the
aspirating smoke detector incorporates technology which provides for constant (or near 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), then a fault signal shall be given when there
is a loss of 50 % and greater of sampling points.
In both cases a period of 300 s is allowed between the fault being applied and the fault signal being
given.
NOTE This time is independent of any delay times between signalling the fault and its indication at the CIE
and is to allow for spurious short term flow variations which would otherwise result in unwanted fault signals.
5.9.3 Where an aspirating smoke detector has a facility to memorize the “normal” flow (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 under level 3 access (as
defined in EN 54-2).
5.9.4 Power cycling the aspirating smoke detector (turning it off and on) shall not result in a change
to the memorized normal flow.
5.10 Power supply
The power for the aspirating detector shall be supplied by a power supply complying with EN 54-4.
NOTE This power supply may be common to the control and indicating equipment.
5.11 Data
Aspirating smoke detectors shall either be supplied with sufficient technical, installation and
maintenance data to enable their correct installation, sensitivity setting and operation or, if all of these
data are not supplied with each ASD then 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 used configuration.
These data shall be referred to in the test report to describe and determine the 'worst case'
configuration(s) to be used in the fire tests (see 6.15) and the transport time for the sampling point(s)
in the fire test room.
NOTE 1 The transport time should not include any processing time and is specifically limited to the time it
takes to transport aerosols from the sampling point (in the fire test room) to the sensing element.
The method used for determining the classification shall be clearly stated.
NOTE 2 This is likely to take into account the following parameters:
 sizes and number of sampling points (maximum and minimum) and any limitations on their
position along the sampling device,
 sensitivity settings for the detector and how this should be adjusted,
 details of permitted sampling device arrangement (e.g. single pipe, branch, H-configurations),
 maximum length of the sampling device (e.g. the maximum pipe length and branch length),
 aspirator setting (if adjustable).
5.12 Additional requirements for software controlled detectors
5.12.1 General
For detectors that rely on software control to fulfil the requirements of this standard, the requirements
of 5.12.2, 5.12.3 and 5.12.4 shall be met.
5.12.2 Software documentation
5.12.2.1 The manufacturer shall submit documentation to the testing authority which gives an
overview of the software design. This documentation shall be in sufficient detail for the design to be
inspected for compliance with this standard 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) brief description of the modules and the functions that they perform,
2) way in which the modules interact,
3) overall hierarchy of the program,
4) way in which the software interacts with the hardware of the detector,
5) 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.
5.12.2.2 The manufacturer shall also have available detailed design documentation, which only
needs to be provided 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;
c) full source code listings, as hard copy or in machine-readable form (e.g. ASCII-code), including
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)
5.12.3 Software design
To ensure the reliability of the detector, the following requirements for software design shall apply:
a) software shall have a modular structure,
b) design of the interfaces for manually and automatically generated data shall not permit invalid
data to cause error in the program operation,
c) software shall be designed to avoid the occurrence of deadlock of the program flow.
5.12.4 The storage of programs and data
The program necessary to comply with this European Standard and any pre-set data, such as
manufacturer's settings, shall be held in non-volatile memory. Writing to areas of memory containing
this program and data shall only be possible 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 which 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.
6 Tests
6.1 General
6.1.1 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 described in
EN 60068-1 as follows:
a) temperature : (15 to 35) °C;
b) relative humidity : (25 to 75) %;
c) air pressure : (86 to 106) kPa.
If variations in these parameters have a significant effect on a measurement, then such variations
shall be kept to a minimum during a series of measurements carried out as part of one test on one
specimen.
6.1.2 Operating conditions for tests
If a test method requires a specimen to be operational, then the specimen shall be connected to
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.
Where an aspirating smoke detector has multiple sensitivity settings, the sensitivity of the DUT during
all tests in Table 3 (with the exception of the fire sensitivity test in 6.15) shall be set at the highest
sensitivity setting used during the fire sensitivity test(s).
NOTE It is not intended that the environmental tests are conducted at all possible sensitivity settings, only at
the highest used during the fire sensitivity test. This is particularly relevant where multiple classes and/or multiple
configurations are submitted.
To allow the flow monitoring function to be checked as required before, during and/or after
environmental tests, the sampling device may be simulated by a simpler sampling device (e.g. stub
pipe with appropriate orifice(s)) to providing a typical airflow through the detector.
During the dry heat, damp heat and cold tests, a sufficient length of pipe shall be installed in the
chamber to allow the temperature of the test aerosol entering the DUT to stabilize at the test
temperature.
The details of the supply and monitoring equipment and the alarm criteria used shall be given in the
test report.
6.1.3 Mounting arrangements
When necessary, 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.
6.1.4 Tolerances
Unless otherwise stated, the tolerances for the environmental test parameters shall be as given in the
basic reference standards for the test (i.e. the relevant Parts of EN 60068-2 as listed in Clause 2).
If a specific tolerance or limit is not specified in a requirement or test procedure, then deviation limits
of ± 5 % shall be applied.
6.1.5 Measurement of response threshold value
6.1.5.1 General
Because there are a number of different types of aspirating detectors available operating on quite
different principles, which have very different ranges of sensitivity, various methods can be used to
measure the response threshold value. The object of any method chosen shall be to determine a
measure of the aerosol concentration, which when passing through the detector, just causes an alarm
to be raised. This can generally be achieved by introducing smoke or an aerosol into the sampled air
stream so that the detector is subjected to a slowly increasing concentration, and recording the
concentration at the moment when an alarm is generated. Because the response threshold value is
only used as a relative measurement, various parameters to measure the aerosol concentration may
be used, providing that the chosen parameter is essentially proportional to the particle number
concentration, for the particular test aerosol. For further information it is recommended to refer to
Annex A.
6.1.5.2 Typical RTV measurement procedure
The specimen for which the response threshold value is to be measured shall be connected to
measuring apparatus as recommended in Annex A. The airflow through the detector shall be controlled
to a typical rate within the manufacturer's specification.
The DUT shall be connected to its supply and monitoring equipment as described in 6.1.2 and shall be
allowed to stabilize for a period of at least 15 min unless otherwise specified by the manufacturer.
Before commencing each measurement the measuring apparatus and DUT shall be purged sufficiently
to ensure that the new results are not affected by the previous measurement.
The aerosol concentration shall then be increased at an appropriate rate, depending upon the
detector's sensitivity. The rate of increase in aerosol density shall be similar for all measurements on
a particular detector type. It is recommended that the alarm signal is generated between 2 min and
10 min after the start of the measurement. Preliminary testing may be necessary to determine the
appropriate rate for a particular detector type.
The response threshold value N shall be taken as the aerosol concentration at the moment when the
detector gives the alarm signal. The particular measuring unit for the aerosol concentration depends
on the measuring apparatus employed.
6.1.6 Test of the airflow monitoring facility
In accordance with the requirement in 5.9.2, when testing of the air flow monitoring facility is required it
shall be tested as follows:
a) where the volumetric flow is not maintained constant, the increase and decrease in flow shall be
verified as follows:
1) the normal volumetric airflow (e.g. litres/min) (Fn) shall be determined from the sampling
configuration used for the fire tests using suitable instrumentation;
2) the DUT shall be set up at a Test flow rate (Ft = Fn+/-10%) for testing the airflow
monitoring. For a DUT that has a memorised normal flow the Ft shall be entered to the
memory in accordance with the normal operating instructions for the DUT. This shall only
be done once at the start of each environmental test and shall not be done during or after
conditioning;
3) for decreased flow the volumetric airflow is decreased from Ft by 20 % (Ft-20%);
4) for increased flow the volumetric airflow is increased from Ft by 20 % (Ft+20%);
An example of a possible practical arrangement to achieve this test is given in Annex K.
b) where the tests of a) cannot be applied (e.g. where the volumetric flow is maintained constant),
the flow monitoring facility is to be verified by the loss of maximum of the 50 % of sampling points.
The sampling points lost shall be those furthest from the sensing element
...