Fire resistance tests — Fire dampers for air distribution systems — Part 2: Intumescent dampers

This document specifies a test method for the determination of the resistance of fire dampers to heat, and for the evaluation of their ability to prevent fire and smoke from spreading from one fire compartment to another through an air distribution system. This document describes the test requirements related to intumescent fire dampers. It is intended for intumescent fire dampers that are expected to be classified as EI dampers. Without the addition of a mechanical damper, they are unable to achieve the “S” classification, which includes a leakage limit imposed at ambient temperature. This document is not intended to be used for dampers used only in smoke control systems, for testing fire protection devices which only deal with air transfer applications, or for dampers used in suspended ceilings, as the installation of the damper and duct can have an adverse effect on the performance of the suspended ceiling, requiring other methods of evaluation. NOTE "Air transfer" is a low-pressure application through a fire separation door (or wall, floor) without any connection to an air duct.

Essais de résistance au feu — Clapets résistant au feu pour des systèmes de distribution d’air — Partie 2: Clapets intumescents

General Information

Status
Published
Publication Date
24-Jun-2021
Current Stage
6060 - International Standard published
Start Date
25-Jun-2021
Due Date
21-Jan-2023
Completion Date
25-Jun-2021
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INTERNATIONAL ISO
STANDARD 21925-2
First edition
2021-06
Fire resistance tests — Fire dampers
for air distribution systems —
Part 2:
Intumescent dampers
Essais de résistance au feu — Clapets résistant au feu pour des
systèmes de distribution d’air —
Partie 2: Clapets intumescents
Reference number
ISO 21925-2:2021(E)
©
ISO 2021

---------------------- Page: 1 ----------------------
ISO 21925-2:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO 21925-2:2021(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of the test . 2
5 Apparatus . 3
6 Test construction .12
6.1 General .12
6.1.1 Introduction .12
6.1.2 Side to be tested.13
6.1.3 Dampers installed in both walls and floors .13
6.1.4 Dampers installed within a structural opening .13
6.1.5 Dampers mounted onto face of wall or floor .13
6.1.6 Dampers remote from wall or floor .13
6.1.7 Minimum separation between dampers .13
6.2 Size of specimen .13
6.3 Specimen installation .15
6.4 Supporting construction .15
6.4.1 Principles .15
6.4.2 Recommended supporting constructions .16
6.5 Conditioning .17
7 Determination of leakage of connecting duct and measuring station.17
8 Opening and closing cycles .17
9 Fire test .18
10 Classification and criteria .19
10.1 General .19
10.2 Number of tests required .19
11 Test report .20
12 Direct field of application of the test results .21
12.1 Size of fire damper .21
12.2 Fire dampers installed within structural openings .21
12.3 Fire dampers mounted onto the face of a wall .21
12.4 Fire dampers remote from a wall or floor .21
12.5 Separation between fire dampers and between fire dampers and construction
elements .22
12.6 Supporting constructions .22
Annex A (normative) Durability .23
Annex B (informative) Test apparatus .24
Annex C (informative) Reaction to fire tests — Intumescent materials .26
Annex D (informative) The use and application of intumescent fire dampers in ducted air
distribution systems .37
Bibliography .44
© ISO 2021 – All rights reserved iii

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ISO 21925-2:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 92, Fire Safety, Subcommittee SC 2, Fire
containment.
A list of all parts in the ISO 21925 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO 21925-2:2021(E)
Fire resistance tests — Fire dampers for air distribution
systems —
Part 2:
Intumescent dampers
WARNING — For suitable health precautions to be taken, attention is drawn to the possibility
that toxic or harmful gases can be released while the test is being conducted.
1 Scope
This document specifies a test method for the determination of the resistance of fire dampers to
heat, and for the evaluation of their ability to prevent fire and smoke from spreading from one fire
compartment to another through an air distribution system.
This document describes the test requirements related to intumescent fire dampers. It is intended for
intumescent fire dampers that are expected to be classified as EI dampers. Without the addition of a
mechanical damper, they are unable to achieve the “S” classification, which includes a leakage limit
imposed at ambient temperature.
This document is not intended to be used for dampers used only in smoke control systems, for testing
fire protection devices which only deal with air transfer applications, or for dampers used in suspended
ceilings, as the installation of the damper and duct can have an adverse effect on the performance of the
suspended ceiling, requiring other methods of evaluation.
NOTE "Air transfer" is a low-pressure application through a fire separation door (or wall, floor) without any
connection to an air duct.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
test construction
complete test assembly, consisting of the separating element (3.3), damper and duct sections and
penetration seals (if any)
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ISO 21925-2:2021(E)

3.2
supporting construction
wall, partition or floor into which the damper and duct section are installed for the test
3.3
separating element
wall, partition or floor into which the damper and duct are installed in the building
3.4
connecting duct
duct section between the damper or separating element (3.3) and the measuring station (3.5)
3.5
measuring station
equipment consisting of pipe system with an orifice plate or venturi and an air flow straightener (if
required), installed between the connecting duct (3.4) and the exhaust equipment (3.6) to determine the
volume flow rate of gases passing through the damper under test
3.6
exhaust equipment
equipment consisting of a fan and balancing or dilution dampers to apply and maintain the
underpressure in the connecting duct (3.4)
3.7
fire damper
mobile closure within a duct which is operated automatically or manually and is designed to prevent
the spread of fire
3.8
intumescent
term describing the phenomenon of expansion in excess of normal thermal expansion under the action
of heat normally generated by the fire
3.9
intumescent dampers
non-mechanical device installed in a ducted system that intumesces when exposed to hot gases to
prevent the spread of fire
3.10
intumescent sheet
intumescent (3.8) material manufactured in rigid or flexible thin sections, typically 1 mm to 4 mm thick,
usually cut into strips for incorporation into the fire damper (3.7)
3.11
covered intumescent
partly enclosed intumescent (3.8) material to provide protection, modify the behaviour, improve the
surface finish and/or enhance the aesthetics of the fire damper (3.7)
3.12
skinned intumescent material
totally enclosed intumescent (3.8) material on all faces and edges to provide protection, modify the
behaviour and improve the surface finish and/or the aesthetics of the fire damper (3.7)
4 Principles of the test
4.1 General
The damper with its fixing device is built into, or attached directly or remotely via a section of
ducting, to a fire-separating building element according to good practice. Temperature and integrity
measurements are carried out in various parts of the test construction during the test. The tightness of
2 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

the damper system is measured by direct flow measurements whilst maintaining a constant pressure
differential across the closed damper of 300 Pa. For special applications, higher underpressures may be
employed.
4.2 Additional tests
Additional tests are included to provide an assessment on the operational reliability of the intumescent
dampers. See Annex C for information on reaction to fire tests. The conditions specified in Annex A
apply.
Annex D provides general information on the use and application of intumescent dampers.
5 Apparatus
5.1 General
The test apparatus specified in 5.2 to 5.11, including the instrumentation, shall be in accordance with
ISO 834-1 except where specifically stated otherwise. Intumescent dampers give off some moisture.
A suitable condensing device shall therefore be installed before the flow-measuring device. This will
be deemed to be effective if the gas temperature within the flow-measuring device does not exceed
40 °C at any time during the test. An example of a suitable condensing device is a water tank fed with
water at ambient temperature with approximately 9 m of measuring duct immersed in the tank prior to
reaching the measuring device.
An example of a test arrangement is shown in Figure 1.
5.2 Furnace, capable of achieving the heating and pressure conditions specified in ISO 834-1.
5.3 Damper under test, attached to the connecting duct in accordance with the manufacturer’s
instructions.
5.4 Connecting duct, of all welded construction fabricated from (1,5 ± 0,1) mm thick steel with a
width and height appropriate to the size of the damper under test. The duct shall have a length of twice
the diagonal dimension of the damper, up to a maximum of 2 m. The connecting duct shall be provided
with a gas-tight observation port.
5.5 Measuring station, consisting of an orifice plate, venturi, or other suitable device, an air flow
straightener (if required) and straight lengths of pipe sized in accordance with ISO 5167-1 installed
between the connecting duct and the exhaust fan to determine the volume flow rate of gases passing
through the damper under test. When testing dampers installed in floors, it is still possible to use the
measuring station horizontally. A suitable mounting detail is shown in Figure 2.
5.6 Exhaust fan system, capable of controlling flow rates and maintaining a pressure difference
between the connecting duct and the furnace, as required, when the damper is closed.
Regardless of what test pressure is chosen, the fan should be capable of achieving a 200 Pa pressure
difference higher than the test pressure difference chosen for the test.
Regulation of the 300 Pa (or higher pressure differential) may be by means of a dilution damper installed
just before the fan inlet. The pressure shall be controlled to within ±5 % of the required pressure. A
balancing damper shall be fitted at the outlet of the fan to adjust the pressure range of the systems to
suit the damper under test. A variable speed fan may be used instead of the dilution damper.
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ISO 21925-2:2021(E)

5.7 Instrumentation for measuring and recording the furnace temperature, in accordance with
ISO 834-1. Locations of the furnace thermocouples for a number of different test arrangements are
shown in Figures 3, 4, 5, 6, 7 and 8.
The gas temperature adjacent to the flow measuring device shall be measured by a 0,25 mm bare
wire thermocouple enclosed in a 6 mm diameter porcelain twin wall tube with its measuring junction
located at the centreline of the measuring duct and at a distance equal to twice the diameter of the
measuring duct downstream from the flow measuring device. A similar thermocouple shall be located
at the exit from the connecting duct plenum (see Figures 1 and 2). Alternative thermocouples may be
used provided it can be shown that they have equivalent response time.
5.8 Instrumentation for measuring and recording surface temperature, in accordance with
ISO 834-1. This shall be located in the positions shown in Figures 3, 4, 5, 6, 7 or 8, depending on the
method of mounting the damper selected.
5.9 Instrumentation for measuring pressure differential between the furnace and the connecting
duct. A pressure tapping shall be located on the centreline of one vertical side wall of the connecting
duct. Instrumentation shall have a 300 Pa measurement capacity higher than the test pressure chosen
for the test. Instrumentation shall also be provided for measuring the pressure difference between inside
and outside (ambient) of the furnace.
5.10 Timing device, capable of running throughout the test period.
5.11 Gap gauges and cotton pad, according to ISO 834-1, to judge the integrity of the joints between
the damper and its connecting duct and the damper assembly and the supporting construction of the test
arrangement.
4 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 supporting construction (wall)
2 2 × diagonal dimension of the damper (to a maximum of 2 m)
3 pressure sensor (on centreline)
4 observation port
5 orifice plate or venturi
6 pressure differential (300 Pa)
7 pressure differential control box
8 pressure sensor in laboratory
9 pressure control dilution damper
10 pneumatic actuator or manual control
11 balancing damper
12 fan
13 flexible connecting duct
14 support
15 thermocouple
16 support
17 flow straightener
18 flange
19 support
20 thermocouple at exit from plenum
21 connecting duct
22 test damper
23 furnace chamber
24 pressure sensor (on centreline of damper)
a
Distance from thermocouple to orifice plate = 2 × diameter of the measuring duct.
Figure 1 — Example of general test arrangement
© ISO 2021 – All rights reserved 5

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 pressure sensor
2 pressure differential (300 Pa)
3 pressure sensor in laboratory
4 pressure differential control box
5 pressure control dilution damper
6 balancing damper
7 fan
8 pneumatic actuator or manual control
9 flexible connecting duct
10 thermocouple
11 support
12 orifice plate or venturi
13 flange
14 connecting duct
15 thermocouple at exit from plenum
16 flow straightener
17 support
18 supporting construction {floor)
19 furnace chamber
20 test damper
21 pressure sensor
a
Dimension equal to the diameter of the measuring station.
b
Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.
c
2 × diagonal dimension of the damper (to a maximum of 2 m).
Figure 2 — Example of an alternative arrangement when testing dampers in floors
6 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 connecting angle
6 infill material, provided it is necessary
7 test damper
8 insulated ductwork
9 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T T unexposed surface thermocouples (minimum of one each side)
1, 2
Figure 3 — Position of surface thermocouples when damper is installed in an insulated duct
© ISO 2021 – All rights reserved 7

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 connecting angle
6 infill material, provided it is necessary
7 test damper
8 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 4 — Position of surface thermocouples when damper is installed in a non-insulated duct
8 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 test damper
6 furnace thermocouples, 4 places
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 5 — Damper mounted onto face of supporting construction within the furnace
© ISO 2021 – All rights reserved 9

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 supporting construction
2 support
3 connecting duct
4 test damper
5 connecting angle
6 furnace
7 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 6 — Damper mounted onto face of supporting construction outside the furnace
10 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 furnace
2 floor, for example
3 suitable attachment as in practice
4 insulation, provided it is necessary
5 insulated duct
6 supporting construction
7 support
8 connecting duct
9 connecting angle
10 test damper
11 furnace thermocouples, 4 places
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 7 — Damper mounted remote from the supporting construction and within the furnace
chamber
© ISO 2021 – All rights reserved 11

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ISO 21925-2:2021(E)

Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 damper insulation, provided it is necessary
4 test damper
5 support
6 connecting duct
7 connecting angle
8 connecting angle
9 insulated duct
10 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
L dimension of insulation where insulation is necessary
i
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 8 — Damper mounted remotely from the supporting construction and outside the
furnace chamber
6 Test construction
6.1 General
6.1.1 Introduction
The test construction shall be representative of the construction for which information is required.
Only a maximum of two dampers may be tested at one time.
12 © ISO 2021 – All rights reserved

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ISO 21925-2:2021(E)

6.1.2 Side to be tested
Where dampers are asymmetrical, they shall be tested from both sides, as it is probably not possible to
determine which side will give the worse result. Symmetrical dampers need only be tested from one
side.
If testing is carried out from one side only (i.e. one specimen) the reason for this shall be clearly stated
in the report.
6.1.3 Dampers installed in both walls and floors
Dampers which are to be employed in both walls and floors shall be tested in both orientations, unless
it can be demonstrated that one is more onerous.
6.1.4 Dampers installed within a structural opening
Dampers to be positioned within a structural opening shall be tested as shown in Figure 1 when
installed in a wall and as shown in Figure 2 when installed in a floor.
6.1.5 Dampers mounted onto face of wall or floor
Uninsulated dampers mounted on a wall or floor and attached to the face of a structure shall be tested
with the damper positioned within the furnace as shown in Figure 5. Insulated dampers shall be tested
from both sides so that the insulation properties of the damper body, and where appropriate the duct,
can be evaluated. An example of a damper mounted to the wall/floor outside the furnace is shown in
Figure 6.
6.1.6 Dampers remote from wall or floor
6.1.6.1 Within the furnace
Dampers remote from the wall or floor and separate from the structure shall be attached to a length of
ductwork. For test purposes, the duct shall be attached to the supporting construction with the damper
installed at the duct end within the furnace, as shown in Figure 7. This length of ductwork shall be
(150 ± 50) mm long and insulated to the extent necessary to ensure that it remains intact throughout
the test. The distance between the outer surface of the duct and the furnace wall or floor shall not be
less than 500 mm.
6.1.6.2 Outside the furnace
For dampers that are to be mounted onto a section of duct outside the furnace, as shown in Figure 8, the
length of duct shall be (500 ± 50) mm.
NOTE An uninsulated damper mounted on a section of a duct outside the furnace does not need to be tested.
6.1.7 Minimum separation between dampers
Where two dampers are to be tested at the same time, the distance between the dampers shall not be
less than 200 mm, as shown in Figures 9 and 10. Where the dampers are mounted in a wall or partition,
but are not located in the same horizontal plane, the required furnace pressure is determined at the
horizontal plane of the lower damper; see 9.8 a) and Figure 1.
6.2 Size of specimen
The largest sized damper should be fire tested and, provided the damper satisfies the appropriate fire
leakage criteria, the results can be extended to smaller sizes of dampers whose dimensions relative
to width, height and length are smaller than that tested,
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 21925-2
ISO/TC 92/SC 2
Fire resistance tests — Fire dampers
Secretariat: ANSI
for air distribution systems —
Voting begins on:
2021-03-25
Part 2:
Voting terminates on:
Intumescent dampers
2021-05-20
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 21925-2:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
©
NATIONAL REGULATIONS. ISO 2021

---------------------- Page: 1 ----------------------
ISO/FDIS 21925-2:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

---------------------- Page: 2 ----------------------
ISO/FDIS 21925-2:2021(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles of the test . 2
5 Apparatus . 3
6 Test construction .12
6.1 General .12
6.1.1 Introduction .12
6.1.2 Side to be tested.13
6.1.3 Dampers installed in both walls and floors .13
6.1.4 Dampers installed within a structural opening .13
6.1.5 Dampers mounted onto face of wall or floor .13
6.1.6 Dampers remote from wall or floor .13
6.1.7 Minimum separation between dampers .13
6.2 Size of specimen .13
6.3 Specimen installation .15
6.4 Supporting construction .15
6.4.1 Principles .15
6.4.2 Recommended supporting constructions .16
6.5 Conditioning .17
7 Determination of leakage of connecting duct and measuring station.17
8 Opening and closing cycles .17
9 Fire test .18
10 Classification and criteria .19
10.1 Number of tests required .19
11 Test report .20
12 Direct field of application of the test results .21
12.1 Size of fire damper .21
12.2 Fire dampers installed within structural openings .21
12.3 Fire dampers mounted onto the face of a wall .21
12.4 Fire dampers remote from a wall or floor .21
12.5 Separation between fire dampers and between fire dampers and construction
elements .21
12.6 Supporting constructions .22
Annex A (normative) Durability .23
Annex B (informative) Test apparatus .24
Annex C (informative) Reaction to fire tests — Intumescent materials .26
Annex D (informative) The use and application of intumescent fire dampers in ducted air
distribution systems .37
Bibliography .44
© ISO 2021 – All rights reserved iii

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ISO/FDIS 21925-2:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 92, Fire Safety, Subcommittee SC 2, Fire
containment.
A list of all parts in the ISO 21925 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

---------------------- Page: 4 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 21925-2:2021(E)
Fire resistance tests — Fire dampers for air distribution
systems —
Part 2:
Intumescent dampers
WARNING — For suitable health precautions to be taken, attention is drawn to the possibility
that toxic or harmful gases can be released while the test is being conducted.
1 Scope
This document specifies a test method for the determination of the resistance of fire dampers to
heat, and for the evaluation of their ability to prevent fire and smoke from spreading from one fire
compartment to another through an air distribution system.
This document describes the test requirements related to intumescent fire dampers. It is intended for
intumescent fire dampers that are expected to be classified as EI dampers. Without the addition of a
mechanical damper, they are unable to achieve the “S” classification, which includes a leakage limit
imposed at ambient temperature.
This document is not intended to be used for dampers used only in smoke control systems, for testing
fire protection devices which only deal with air transfer applications, or for dampers used in suspended
ceilings, as the installation of the damper and duct can have an adverse effect on the performance of the
suspended ceiling, requiring other methods of evaluation.
NOTE "Air transfer" is a low-pressure application through a fire separation door (or wall, floor) without any
connection to an air duct.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 834-1, Fire-resistance tests — Elements of building construction — Part 1: General requirements
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
test construction
complete test assembly, consisting of the separating element (3.3), damper and duct sections and
penetration seals (if any)
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3.2
supporting construction
wall, partition or floor into which the damper and duct section are installed for the test
3.3
separating element
wall, partition or floor into which the damper and duct are installed in the building
3.4
connecting duct
duct section between the damper or separating element (3.3) and the measuring station (3.5)
3.5
measuring station
equipment consisting of pipe system with an orifice plate or venturi and an air flow straightener (if
required), installed between the connecting duct (3.4) and the exhaust equipment (3.6) to determine the
volume flow rate of gases passing through the damper under test
3.6
exhaust equipment
equipment consisting of a fan and balancing or dilution dampers to apply and maintain the
underpressure in the connecting duct (3.4)
3.7
fire damper
mobile closure within a duct which is operated automatically or manually and is designed to prevent
the spread of fire
3.8
intumescent
term describing the phenomenon of expansion in excess of normal thermal expansion under the action
of heat normally generated by the fire
3.9
intumescent dampers
non-mechanical device installed in a ducted system that intumesces when exposed to hot gases to
prevent the spread of fire
3.10
intumescent sheet
intumescent (3.8) material manufactured in rigid or flexible thin sections, typically 1 mm to 4 mm thick,
usually cut into strips for incorporation into the fire damper (3.7)
3.11
covered intumescent
partly enclosed intumescent (3.8) material to provide protection, modify the behaviour, improve the
surface finish and/or enhance the aesthetics of the fire damper (3.7)
3.12
skinned intumescent material
totally enclosed intumescent (3.8) material on all faces and edges to provide protection, modify the
behaviour and improve the surface finish and/or the aesthetics of the fire damper (3.7)
4 Principles of the test
4.1 General
The damper with its fixing device is built into, or attached directly or remotely via a section of
ducting, to a fire-separating building element according to good practice. Temperature and integrity
measurements are carried out in various parts of the test construction during the test. The tightness of
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the damper system is measured by direct flow measurements whilst maintaining a constant pressure
differential across the closed damper of 300 Pa. For special applications, higher underpressures may be
employed.
4.2 Additional tests
Additional tests are included to provide an assessment on the operational reliability of the intumescent
dampers. See Annex C for information on reaction to fire tests. The conditions specified in Annex A apply.
Annex D provides general information on the use and application of intumescent dampers.
5 Apparatus
5.1 General
The test apparatus specified in 5.2 to 5.11, including the instrumentation, shall be in accordance with
ISO 834-1 except where specifically stated otherwise. Intumescent dampers give off some moisture.
A suitable condensing device shall therefore be installed before the flow-measuring device. This will
be deemed to be effective if the gas temperature within the flow-measuring device does not exceed
40 °C at any time during the test. An example of a suitable condensing device is a water tank fed with
water at ambient temperature with approximately 9 m of measuring duct immersed in the tank prior to
reaching the measuring device.
An example of a test arrangement is shown in Figure 1.
5.2 Furnace, capable of achieving the heating and pressure conditions specified in ISO 834-1.
5.3 Damper under test, attached to the connecting duct in accordance with the manufacturer’s
instructions.
5.4 Connecting duct, of all welded construction fabricated from (1,5 ± 0,1) mm thick steel with a
width and height appropriate to the size of the damper under test. The duct shall have a length of twice
the diagonal dimension of the damper, up to a maximum of 2 m. The connecting duct shall be provided
with a gas-tight observation port.
5.5 Measuring station, consisting of an orifice plate, venturi, or other suitable device, an air flow
straightener (if required) and straight lengths of pipe sized in accordance with ISO 5167-1 installed
between the connecting duct and the exhaust fan to determine the volume flow rate of gases passing
through the damper under test. When testing dampers installed in floors, it is still possible to use the
measuring station horizontally. A suitable mounting detail is shown in Figure 2.
5.6 Exhaust fan system, capable of controlling flow rates and maintaining a pressure difference
between the connecting duct and the furnace, as required, when the damper is closed.
Regardless of what test pressure is chosen, the fan should be capable of achieving a 200 Pa pressure
difference higher than the test pressure difference chosen for the test.
Regulation of the 300 Pa (or higher pressure differential) may be by means of a dilution damper installed
just before the fan inlet. The pressure shall be controlled to within ±5 % of the required pressure. A
balancing damper shall be fitted at the outlet of the fan to adjust the pressure range of the systems to
suit the damper under test. A variable speed fan may be used instead of the dilution damper.
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5.7 Instrumentation for measuring and recording the furnace temperature, in accordance with
ISO 834-1. Locations of the furnace thermocouples for a number of different test arrangements are
shown in Figures 3, 4, 5, 6, 7 and 8.
The gas temperature adjacent to the flow measuring device shall be measured by a 0,25 mm bare
wire thermocouple enclosed in a 6 mm diameter porcelain twin wall tube with its measuring junction
located at the centreline of the measuring duct and at a distance equal to twice the diameter of the
measuring duct downstream from the flow measuring device. A similar thermocouple shall be located
at the exit from the connecting duct plenum (see Figures 1 and 2). Alternative thermocouples may be
used provided it can be shown that they have equivalent response time.
5.8 Instrumentation for measuring and recording surface temperature, in accordance with
ISO 834-1. This shall be located in the positions shown in Figures 3, 4, 5, 6, 7 or 8, depending on the
method of mounting the damper selected.
5.9 Instrumentation for measuring pressure differential between the furnace and the connecting
duct. A pressure tapping shall be located on the centreline of one vertical side wall of the connecting
duct. Instrumentation shall have a 300 Pa measurement capacity higher than the test pressure chosen
for the test. Instrumentation shall also be provided for measuring the pressure difference between inside
and outside (ambient) of the furnace.
5.10 Timing device, capable of running throughout the test period.
5.11 Gap gauges and cotton pad, according to ISO 834-1, to judge the integrity of the joints between
the damper and its connecting duct and the damper assembly and the supporting construction of the test
arrangement.
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Dimensions in millimetres
Key
1 supporting construction (wall)
2 2 × diagonal dimension of the damper (to a maximum of 2 m)
3 pressure sensor (on centreline)
4 observation port
5 orifice plate or venturi
6 pressure differential (300 Pa)
7 pressure differential control box
8 pressure sensor in laboratory
9 pressure control dilution damper
10 pneumatic actuator or manual control
11 balancing damper
12 fan
13 flexible connecting duct
14 support
15 thermocouple
16 support
17 flow straightener
18 flange
19 support
20 thermocouple at exit from plenum
21 connecting duct
22 test damper
23 furnace chamber
24 pressure sensor (on centreline of damper)
a
Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.
Figure 1 — Example of general test arrangement
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Dimensions in millimetres
Key
1 pressure sensor
2 pressure differential (300 Pa)
3 pressure sensor in laboratory
4 pressure differential control box
5 pressure control dilution damper
6 balancing damper
7 fan
8 pneumatic actuator or manual control
9 flexible connecting duct
10 thermocouple
11 support
12 orifice plate or venturi
13 flange
14 connecting duct
15 thermocouple at exit from plenum
16 flow straightener
17 support
18 supporting construction {floor)
19 furnace chamber
20 test damper
21 pressure sensor
a
Dimension equal to the diameter of the measuring station.
b
Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.
c
2 × diagonal dimension of the damper (to a maximum of 2 m).
Figure 2 — Example of an alternative arrangement when testing dampers in floors
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Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 connecting angle
6 infill material, provided it is necessary
7 test damper
8 insulated ductwork
9 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T T unexposed surface thermocouples (minimum of one each side)
1, 2
Figure 3 — Position of surface thermocouples when damper is installed in an insulated duct
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Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 connecting angle
6 infill material, provided it is necessary
7 test damper
8 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 4 — Position of surface thermocouples when damper is installed in a non-insulated duct
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Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 test damper
6 furnace thermocouples, 4 places
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 5 — Damper mounted onto face of supporting construction within the furnace
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Dimensions in millimetres
Key
1 supporting construction
2 support
3 connecting duct
4 test damper
5 connecting angle
6 furnace
7 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
T , supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 6 — Damper mounted onto face of supporting construction outside the furnace
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Dimensions in millimetres
Key
1 furnace
2 floor, for example
3 suitable attachment as in practice
4 insulation, provided it is necessary
5 insulated duct
6 supporting construction
7 support
8 connecting duct
9 connecting angle
10 test damper
11 furnace thermocouples, 4 places
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 7 — Damper mounted remote from the supporting construction and within the
furnace chamber
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Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 damper insulation, provided it is necessary
4 test damper
5 support
6 connecting duct
7 connecting angle
8 connecting angle
9 insulated duct
10 furnace thermocouples, 4 places
L dimension to be specified by damper manufacturer
L dimension of insulation where insulation is necessary
i
T supporting construction unexposed surface thermocouples (minimum of one each side)
s
T , T unexposed surface thermocouples (minimum of one each side)
1 2
Figure 8 — Damper mounted remotely from the supporting construction and outside the
furnace chamber
6 Test construction
6.1 General
6.1.1 Introduction
The test construction shall be representative of the construction for which information is required.
Only a maximum of two dampers may be tested at one time.
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6.1.2 Side to be tested
Where dampers are asymmetrical, they shall be tested from both sides, as it is probably not possible to
determine which side will give the worse result. Symmetrical dampers need only be tested from one side.
If testing is carried out from one side only (i.e. one specimen) the reason for this shall be clearly stated
in the report.
6.1.3 Dampers installed in both walls and floors
Dampers which are to be employed in both walls and floors shall be tested in both orientations, unless
it can be demonstrated that one is more onerous.
6.1.4 Dampers installed within a structural opening
Dampers to be positioned within a structural opening shall be tested as shown in Figure 1 when
installed in a wall and as shown in Figure 2 when installed in a floor.
6.1.5 Dampers mounted onto face of wall or floor
Uninsulated dampers mounted on a wall or floor and attached to the face of a structure shall be tested
with the damper positioned within the furnace as shown in Figure 5. Insulated dampers shall be tested
from both sides so that the insulation properties of the damper body, and where appropriate the duct,
can be evaluated. An example of a damper mounted to the wall/floor outside the furnace is shown in
Figure 6.
6.1.6 Dampers remote from wall or floor
6.1.6.1 Within the furnace
Dampers remote from the wall or floor and separate from the structure shall be attached to a length of
ductwork. For test purposes, the duct shall be attached to the supporting construction with the damper
installed at the duct end within the furnace, as shown in Figure 7. This length of ductwork shall be
(150 ± 50) mm long and insulated to the extent necessary to ensure that it remains intact throughout
the test. The distance between the outer surface of the duct and the furnace wall or floor shall not be
less than 500 mm.
6.1.6.2 Outside the furnace
For dampers that are to be mounted onto a section of duct outside the furnace, as shown in Figure 8, the
length of duct shall be (500 ± 50) mm.
NOTE An uninsulated damper mounted on a section of a duct outside the furnace does not need to be tested.
6.1.7 Minimum separation between dampers
Where two dampers are to be tested at the same time, the distance between the dampers shall not be
less than 200 mm, as shown in Figures 9 and 10. Where the dampers are mounted in a wall or partition,
but are not located in the same horizontal plane, the required furnace pressure is determined at the
horizontal plane of the
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