ISO/DIS 21925-2

Fire resistance tests -- Fire dampers for air distribution systems

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DRAFT INTERNATIONAL STANDARD
ISO/DIS 21925-2
ISO/TC 92/SC 2 Secretariat: ANSI
Voting begins on: Voting terminates on:
2020-07-28 2020-10-20
Fire resistance tests — Fire dampers for air distribution
systems —
Part 2:
Intumescent dampers
ICS: 13.220.50
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
This document is circulated as received from the committee secretariat.
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 21925-2:2020(E)
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 SUPPORTING DOCUMENTATION. ISO 2020
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ISO/DIS 21925-2:2020(E) Contents

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Foreword........................................................................................................................................................................4

Introduction..............................................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

1 Scope (mandatory)..........................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

2 Normative references(mandatory) ..........................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

3 Terms and definitions(mandatory)..........................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

4 Clause title autonumber................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

5 Clause title .........................................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

5.1 Subclause autonumber..................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

5.1.1 Subclause autonumber............................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

6 Clause title .........................................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

Annex A (informative) Annex title e.g. Example of a figure and a table””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

Bibliography .............................................................................................................””‘”Ǩ‘‘ƒ”‘–†‡ˆ‹‡†Ǥ

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© ISO 2020 – All rights reserved
ISO/DIS 21925-2:2020(E)
Contents

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Foreword ........................................................................................................................................................................ 4

Introduction .............................................................................................................. Error! Bookmark not defined.

1 Scope (mandatory) .......................................................................................... Error! Bookmark not defined.

2 Normative references (mandatory) .......................................................... Error! Bookmark not defined.

3 Terms and definitions (mandatory) .......................................................... Error! Bookmark not defined.

4 Clause title autonumber ................................................................................ Error! Bookmark not defined.

5 Clause title ......................................................................................................... Error! Bookmark not defined.

5.1 Subclause autonumber .................................................................................. Error! Bookmark not defined.

5.1.1 Subclause autonumber ............................................................................ Error! Bookmark not defined.

6 Clause title ......................................................................................................... Error! Bookmark not defined.

Annex A (informative) Annex title e.g. Example of a figure and a tableError! Bookmark not defined.

Bibliography ............................................................................................................. Error! Bookmark not defined.

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ISO 21925-2:2020
ISO/DIS 21925-2:2020(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 on 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 the following URL:

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee 92, Fire Safety, Subcommittee 2, Fire Containment.

A list of all parts in the ISO 21925 series can be found on the ISO website.
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© ISO 2020 – All rights reserved
ISO/DIS 21925-2:2020(E)
Fire resistance tests — Fire dampers for air distribution
systems — Part 2: Intumescent dampers

SAFETY WARNING — For suitable health precautions to be taken, the 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 spreading from one fire compartment to another

through an air distribution system.

This part of ISO 21925 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.

It 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 5167-7, Measurement of fluid flow by means of pressure differential devices — Part 7: Orifice plates,

nozzles and Venturi tubes inserted in circular cross-section conduits running full

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:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
test construction

complete test assembly, consisting of the separating element, damper and duct sections and penetration seals

(if any)
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

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ISO 21925-2:2020
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3.4
connecting duct
duct section between the damper or separating element and the measuring station
3.5
measuring station

equipment consisting of pipe system with an orifice plate or venturi and an air flow straightener (if any),

installed between the connecting duct and the exhaust equipment 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 (if any), to apply and maintain the

underpressure in the connecting duct
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 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
3.11
covered intumescent

partly enclosed intumescent material to provide protection, modify the behaviour, improve the surface finish

and/or enhance the aesthetics of the fire damper
3.12
skinned intumescent material

totally enclosed intumescent 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
4 Principles of the test

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 in a manner representative of good practice. Temperature and integrity

measurements are carried out in various parts of the test construction during the test. The tightness of 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.

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5 Apparatus

The test apparatus specified in 5.1 to 5.8, 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 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. A

suitable condensing device may be considered to be a water tank fed with water at ambient temperature with

about 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.

5.1 Furnace, capable of achieving the heating and pressure conditions specified in ISO 834-1.

5.2 Damper under test, attached to the connecting duct in accordance with the manufacturer’s

instructions.

5.3 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 2× 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.

5.4 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.

5.5 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.

5.6 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.

5.7 Instrumentation for measuring and recording surface temperature, in accordance with ISO 834-1.

It shall be located, depending on the method of mounting the damper selected, in the positions shown in

Figures 3, 4, 5, 6, 7 or 8.

5.8 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.
5.9 Timing device, capable of running throughout the test period.
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ISO 21925-2:2020
ISO/DIS 21925-2:2020(E)

5.10 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.
Dimensions in millimetres
Key
1 supporting construction (wall)
2 2× diagonal (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)
25 distance: thermocouple to orifice plate = 2 d
Figure 1 — Example of general test arrangement
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Dimensions in millimetres
Key
1 dimension equal to the diameter of the measuring station
2 pressure sensor
3 pressure differential (300 Pa)
4 pressure sensor in laboratory
5 pressure differential control box
6 pressure control dilution damper
7 balancing damper
8 fan
9 pneumatic actuator or manual control
10 flexible connecting duct
11 distance: thermocouple to orifice plate = 2 d
12 thermocouple
13 support
14 orifice plate or venturi
15 flange
16 connecting duct
17 thermocouple at exit from plenum
18 flow straightener
19 support
20 supporting construction {floor)
21 furnace chamber
22 test damper
23 pressure sensor
24 2× diagonal (to a maximum of 2 m)
Figure 2 — Example of an alternative arrangement when testing dampers in floors
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ISO 21925-2:2020
ISO/DIS 21925-2:2020(E)
Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 connecting angle
6 length "L" to be specified by damper manufacturer
7 infill material, provided it is necessary
8 damper
9 insulated ductwork
10 furnace thermocouples, 4 places
T , T , T unexposed surface thermocouples (minimum of one each side)
s 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 damper
8 furnace thermocouples, 4 places
L length to be specified by damper manufacturer
T , T , T unexposed surface thermocouples (minimum of one each side)
s 1 2

Figure 4 — Position of surface thermocouples when damper is installed in a non-insulated duct

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ISO 21925-2:2020
ISO/DIS 21925-2:2020(E)
Dimensions in millimetres
Key
1 furnace
2 supporting construction
3 support
4 connecting duct
5 damper
6 furnace thermocouples, 4 places
T , T , T unexposed surface thermocouples (minimum of one each side)
s 1 2

Figure 5 — Damper mounted onto face of supporting construction within the furnace

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ISO/DIS 21925-2:2020(E)
Dimensions in millimetres
Key
1 supporting construction
2 support
3 connecting duct
4 damper
5 connecting angle
6 furnace
7 furnace thermocouples, 4 places
L length to be specified by damper manufacturer
T , T , T unexposed surface thermocouples (minimum of one each side)
s 1 2

Figure 6 — Damper mounted onto face of supporting construction outside the furnace

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ISO 21925-2:2020
ISO/DIS 21925-2:2020(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 damper
11 furnace thermocouples, 4 places
T , T , T unexposed surface thermocouples (minimum of one each side)
s 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 damper
5 support
6 connecting duct
7 connecting angle
8 connecting angle
9 insulated duct
10 furnace thermocouples, 4 places
L length to be specified by damper manufacturer
L length of insulation where insulation is necessary
T , T , T unexposed surface thermocouples (minimum of one each side)
s 1 2

Figure 8 — Damper mounted remote from the supporting construction and outside the furnace chamber

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ISO 21925-2:2020
ISO/DIS 21925-2:2020(E)
6 Test construction
6.1 General

The test construction shall contain all construction details relevant for test results. Only a maximum of two

dampers may be tested at one time.
6.1.1 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.
6.1.2 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.
6.1.3 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.
6.1.4 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.

6.1.5 Dampers remote from wall or floor
6.1.5.1 Within the furnace

Dampers mounted 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.

6.1.5.2 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 In the case of an uninsulated damper, mounted on a section of a duct outside the furnace, this does

not need to be tested.
6.1.6 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 Figure 9. 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.
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6.2 Size of specimen

The largest size 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, subject to the following verification that all components are the same

thickness and cross-sectional shape. Where it is intended that multiple intumescent dampers will be used in a

duct having a size greater than the individual damper size, the maximum number of dampers in the maximum-

sized duct including all mullions and transoms together with any other supporting structure shall be tested.

Dimensions in millimetres
Key
1 supporting construction
2 damper
Figure 9 — Maximum separation between two dampers
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ISO 21925-2:2020
ISO/DIS 21925-2:2020(E)
Dimensions in millimetres
Key
1 supporting construction (wall)
2 damper
3 pressure of 15 Pa maintained on this plane
Figure 10 — Dampers mounted in different horizontal planes
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ISO/DIS 21925-2:2020(E)
6.3 Specimen installation

The dampers shall be installed as in practice in a supporting construction using methods which are in

accordance with the manufacturer's instructions. Damper manufacturers requiring the damper to be tested in

a length of insulated ductwork shall specify the length over which the duct is to be insulated as shown in

Figure 3.
6.4 Supporting construction
6.4.1 Principles

6.4.1.1 The supporting construction shall be a wall, partition or floor of the type to be used in practice.

6.4.1.2 A test result obtained for a fire damper mounted in a supporting construction made of masonry,

concrete or solid partition (without any cavity) is applicable for the same type of supporting construction with

a thickness and density equal to or greater than those of the supporting construction used for the test.

6.4.1.3 The supporting construction selected shall have fire resistance slightly greater than the required

fire resistance of the damper being tested.

6.4.1.4 If a specific supporting construction different than those described above is selected, the test

results obtained are applicable only to that specific wall, partition or floor.
6.4.2 Recommended supporting constructions

Where the type of supporting construction used in normal practice is not known, then one of the standard

supporting constructions described in Tables 1, 2 or 3 shall be used.
Table 1 — Standard rigid wall construction
Type of construction Thickness Density Test duration
mm kg/m t
Normal concrete/masonry 110 ± 10 2 200 ± 200 t = 2
150 ± 10 2 200 ± 200 2 < t ≤ 3
175 ± 10 2 200 ± 200 3 < t ≤ 4
Aerated concrete 110 ± 10 650 ± 200 t = 2
150 ± 10 650 ± 200 2 < t ≤ 4

This supporting construction may be made from blocks bonded together with mortar or adhesive.

Table 2 — Standard flexible-wall constructions (gypsum plasterboard)
Fire resistance Wall constructions
a b
Number of layers
min Thickness Insulation Thickness
on each side
mm D/ρ mm
30 1 12,5 40/40 75
60 2 12,5 40/40 100
90 2 12,5 60/50 125
120 2 12,5 60/100 150
180 3 12,5 60/100 175
240 3 15,0 80/100 190

D is the thickness in mm of mineral wool insulation inside the wall; ρ is the density in kg/m of mineral wool insulation inside

the wall.
Tolerance of ±10 %.
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ISO 21925-2:2020
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Table 3 — Standard floor constructions
Type of construction Thickness Density Test duration
mm kg/m t
Normal concrete 110 ± 10 2 200 ± 200 t = 1,5
150 ± 10 2 200 ± 200 1,5 < t ≤ 3
175 ± 10 2 200 ± 200 3 < t ≤ 4
Aerated concrete 125 ± 10 650 ± 200 t = 2
150 ± 1
...