Fire resistance tests -- Fire dampers for air distribution systems

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

General Information

Status
Published
Publication Date
24-Jun-2021
Current Stage
5060 - Close of voting Proof returned by Secretariat
Start Date
21-May-2021
Completion Date
20-May-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
---------------------- Page: 3 ----------------------
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)
© ISO 2021 – All rights reserved 1
---------------------- Page: 5 ----------------------
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
---------------------- Page: 6 ----------------------
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.

© ISO 2021 – All rights reserved 3
---------------------- Page: 7 ----------------------
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
---------------------- Page: 8 ----------------------
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)

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
---------------------- Page: 9 ----------------------
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
Dimension equal to the diameter of the measuring station.

Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.

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
---------------------- Page: 10 ----------------------
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)

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
---------------------- Page: 11 ----------------------
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)

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
---------------------- Page: 12 ----------------------
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)

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
---------------------- Page: 13 ----------------------
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)

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
---------------------- Page: 14 ----------------------
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)

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
---------------------- Page: 15 ----------------------
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

T supporting construction unexposed surface thermocouples (minimum of one each side)

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
---------------------- Page: 16 ----------------------
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
---------------------- Page: 3 ----------------------
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

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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
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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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ISO/FDIS 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

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ISO/FDIS 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/FDIS 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.
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ISO/FDIS 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)

Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.

Figure 1 — Example of general test arrangement
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ISO/FDIS 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
Dimension equal to the diameter of the measuring station.

Distance from thermocouple to orifice plate = 2 x diameter of the measuring duct.

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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ISO/FDIS 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)

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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ISO/FDIS 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)

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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ISO/FDIS 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)

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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ISO/FDIS 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)

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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ISO/FDIS 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)

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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ISO/FDIS 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

T supporting construction unexposed surface thermocouples (minimum of one each side)

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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ISO/FDIS 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
...

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