ISO 21925-1:2018

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 spreading from one fire compartment to another through an air distribution system. It is applicable to mechanical fire dampers. 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.

Essais de résistance au feu -- Clapets résistant au feu pour dessystèmes de distribution d’air

General Information

• Status: Published
• Publication Date: 27-Nov-2018
• ICS: 13.220.50 - Fire-resistance of building materials and elements
• Technical Committee: ISO/TC 92/SC 2 - Fire containment
• Drafting Committee: ISO/TC 92/SC 2/WG 4 - Ventilation ducts and fire dampers
• Current Stage: 6060 - International Standard published
• Start Date: 02-Nov-2018
• Completion Date: 28-Nov-2018

RELATIONS

• Revised: ISO 10294-4:2001/Amd 1:2014 - Specific performance requirement for thermal release mechanism based upon performance of thermal release mechanism used in ISO 10294-1 test specimen
• Effective Date: 23-Apr-2020
• Revised: ISO 10294-1:1996/Amd 1:2014 - ISO 10294-1:1996/Amd 1:2014
• Effective Date: 23-Apr-2020
• Revised: ISO 10294-1:1996 - Fire resistance tests -- Fire dampers for air distribution systems
• Effective Date: 15-Apr-2017
• Revised: ISO 10294-4:2001 - Fire resistance tests -- Fire dampers for air distribution systems
• Effective Date: 15-Apr-2017
• Revised: ISO 10294-3:1999 - Fire resistance tests -- Fire dampers for air distribution systems
• Effective Date: 23-Sep-2017
• Revised: ISO 10294-2:1999 - Fire resistance tests -- Fire dampers for air distribution systems
• Effective Date: 23-Sep-2017

Standards Content (sample)

INTERNATIONAL ISO
STANDARD 21925-1
First edition
2018-11
Fire resistance tests — Fire dampers
for air distribution systems —
Part 1:
Mechanical dampers
Reference number
ISO 21925-1:2018(E)
ISO 2018
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ISO 21925-1:2018(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2018

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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Published in Switzerland
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ISO 21925-1:2018(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

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 Side to be tested.............................................................................................................................................................12

6.1.2 Dampers installed in both walls and floors ...........................................................................................13

6.1.3 Dampers installed within a structural opening .................................................................................13

6.1.4 Dampers mounted onto face of wall or floor. .......................................................................................13

6.1.5 Dampers remote from wall or floor .............................................................................................................13

6.1.6 Minimum separation between dampers ..................................................................................................13

6.2 Size of specimen ..................................................................................................................................................................................13

6.3 Thermal release mechanism ....................................................................................................................................................15

6.4 Specimen installation .....................................................................................................................................................................15

6.5 Supporting construction ..............................................................................................................................................................16

6.5.1 Principles .............................................................................................................................................................................16

6.5.2 Recommended supporting constructions ...............................................................................................16

6.6 Conditioning ...........................................................................................................................................................................................17

7 Determination of leakage of connecting duct and measuring station.......................................................17

8 Determination of leakage at ambient temperature ......................................................................................................18

9 Fire test ........................................................................................................................................................................................................................18

10 Classification and criteria ........................................................................................................................................................................19

10.1 Number of tests required ............................................................................................................................................................20

11 Test report ................................................................................................................................................................................................................21

12 Direct field of application of the test results ........................................................................................................................22

12.1 Size of fire damper ............................................................................................................................................................................22

12.2 Fire dampers installed within structural openings ..............................................................................................22

12.3 Fire dampers mounted onto the face of a wall .........................................................................................................22

12.4 Fire dampers remote from a wall or floor ....................................................................................................................22

12.5 Separation between fire dampers and between fire dampers and construction

elements ....................................................................................................................................................................................................22

12.6 Supporting constructions ...........................................................................................................................................................22

Annex A (informative) Historical background of the test methods ...................................................................................24

Annex B (informative) Alternative thermal release mechanisms .......................................................................................27

Annex C (informative) Test of thermal release mechanisms ....................................................................................................28

Annex D (informative) Reliability tests for thermal release mechanisms .................................................................37

Bibliography .............................................................................................................................................................................................................................39

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ISO 21925-1:2018(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.

This first edition of ISO 21925-1 cancels and replaces ISO 10294-1:1996, ISO 10294-2:1999,

ISO 10294-3:1999 and ISO 10294-4:2001, which have been technically revised.
The main changes are as follows:

— integration of the requirements for mechanical dampers, which were published as four separate

parts in the former ISO 10294-series, into a single document.

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.
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ISO 21925-1:2018(E)
Introduction

The material in the former ISO 10294-series was used to assess the fire resistance of mechanical fire

dampers. The separate publications required multiple maintenance work and resources to keep them

current and up-to-date. By having the requirements in a single volume, ISO 21925-1 is intended to

improve efficiency and to be more user friendly. It is also anticipated that a single volume will serve

the continued efforts to promote the alignment of the requirements contained in regional and national

standards for testing fire dampers against this document.

ISO 10294-1:1996 addressed the spread of fire and smoke in buildings through ventilation ducts and

other openings in fire-separating walls and floors.

ISO 10294-2:1999 provided classification, criteria and field of application for the test method given in

ISO 10294-1:1996.

ISO 10294-3:1999 provided a background to the test method and a rationale to the procedures and the

criteria selected with respect to the testing of fire dampers, as given in ISO 10294-1:1996.

ISO 10294-4:2001 provided a test method to evaluate the performance of fire damper-operating

mechanisms.
A list of all parts in the ISO 21925-series can be found on the ISO website.
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INTERNATIONAL STANDARD ISO 21925-1:2018(E)
Fire resistance tests — Fire dampers for air distribution
systems —
Part 1:
Mechanical 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.

It is applicable to mechanical fire dampers. 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

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ISO 21925-1:2018(E)
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 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
actuating mechanism

mechanism, integral or directly associated with the damper which, when initiated by the

damper triggering device, causes the movable component of the damper to change from the "open" to

the "closed" position
3.9
insulated damper

damper which satisfies the integrity, leakage and insulation requirements of this document

3.10
uninsulated damper
damper which satisfies the integrity and leakage requirements of this document
3.11
thermal release mechanism

system which evaluates the parameters of temperature in the airflow of the ventilation duct and

initiates the closing of the fire damper before a predicted threshold limit is reached

Note 1 to entry: The sensing element may be, for example, a fusible link, memory metal, frangible bulb or

electrical sensor.
3.12
threshold limit
maximum operational temperature of the thermal release mechanism
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. Tests are performed

starting with the damper in the open position so as to expose the actuating mechanism of the damper

to furnace conditions. 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. The tightness of the damper in the

closed position is also measured at ambient temperature prior to the start of the furnace test.

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ISO 21925-1:2018(E)

As the test conditions and tolerances for the beginning of the fire test are not specified in detail, the fire

test enables only a limited assessment of the actuating mechanism to be carried out.

Annex A gives the historical background of the test.
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.
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.
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ISO 21925-1:2018(E)

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.

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.
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ISO 21925-1:2018(E)
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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ISO 21925-1:2018(E)
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 21925-1:2018(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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ISO 21925-1:2018(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 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 21925-1:2018(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 21925-1:2018(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 21925-1:2018(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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ISO 21925-1:2018(E)
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
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

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ISO 21925-1:2018(E)

side. For the purposes of determining whether a damper is symmetrical, the presence of the actuating

mechanism can be ignored. However, in such a case, the damper shall be installed so that the actuating

mechanism is on the side away from the furnace, as this is considered to be the more onerous condition

because, as it will be further from the furnace, the time to its operation will be consequently longer.

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
...