ISO 21925-2:2021

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 2021
© ISO 2021
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ii © ISO 2021 – All rights reserved

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
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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different types of ISO documents should be noted. This document was drafted in accordance with the
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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

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)
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 fi
...