Fire containment -- Elements of building construction

ISO 6944-2:2009 establishes a method of test in which kitchen extract ducts are required to provide fire resistance. The requirements are intended to limit the spread of fire from the duct when a fire occurs within the duct and assesses the structural integrity of the duct when a fire occurs in the area surrounding the duct.

Endiguement du feu -- Éléments de construction

General Information

Status
Published
Publication Date
08-Jun-2009
Current Stage
9020 - International Standard under periodical review
Start Date
15-Jul-2020
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ISO 6944-2:2009 - Fire containment -- Elements of building construction
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INTERNATIONAL ISO
STANDARD 6944-2
First edition
2009-06-15
Fire containment — Elements of building
construction —
Part 2:
Kitchen extract ducts
Endiguement du feu — Éléments de construction —
Partie 2: Conduits de ventilation de la cuisine
Reference number
ISO 6944-2:2009(E)
ISO 2009
---------------------- Page: 1 ----------------------
ISO 6944-2:2009(E)
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© ISO 2009

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ii © ISO 2009 – All rights reserved
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ISO 6944-2:2009(E)
Contents Page

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

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

1 Scope ......................................................................................................................................................1

2 Normative references ............................................................................................................................1

3 Terms and definitions ...........................................................................................................................1

4 Test equipment ......................................................................................................................................2

4.1 Fire outside duct....................................................................................................................................2

4.2 Fire inside duct ......................................................................................................................................2

5 Test conditions ......................................................................................................................................3

5.1 Fire outside duct....................................................................................................................................3

5.2 Fire inside duct ......................................................................................................................................3

6 Instrumentation......................................................................................................................................3

6.1 Fire outside duct....................................................................................................................................3

6.2 Fire inside duct ......................................................................................................................................3

7 Test construction...................................................................................................................................8

7.1 Fire outside duct....................................................................................................................................8

7.2 Fire inside duct ......................................................................................................................................8

8 Test procedure.......................................................................................................................................9

8.1 Fire outside duct....................................................................................................................................9

8.2 Fire inside duct ......................................................................................................................................9

9 Performance criteria............................................................................................................................11

9.1 Fire outside duct..................................................................................................................................11

9.2 Fire inside duct ....................................................................................................................................11

10 Expression of results ..........................................................................................................................11

11 Test report ............................................................................................................................................12

Annex A (normative) Optional test equipment and instrumentation — Fire inside duct ..........................13

Annex B (informative) Historical information.................................................................................................15

Bibliography ......................................................................................................................................................17

© ISO 2009 – All rights reserved iii
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ISO 6944-2:2009(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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

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.

ISO 6944-2 was prepared by Technical Committee ISO/TC 92, Fire safety, Subcommittee SC 2, Fire

containment.

ISO 6944 consists of the following parts, under the general title Fire containment — Elements of building

construction:
⎯ Part 1: Ventilation ducts
⎯ Part 2: Kitchen extract ducts
iv © ISO 2009 – All rights reserved
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ISO 6944-2:2009(E)
Introduction

The purpose of this part of ISO 6944 is to measure the ability of a representative duct or duct assembly that is

part of a kitchen extract duct system to resist the spread of fire from one fire compartment to another with the

fire attack being from either the inside of the duct or from the outside of the duct. This part of ISO 6944 is

applicable to vertical and horizontal ducts, with or without branches, taking into account joints and exhaust

openings, as well as suspension devices and penetration points.

The test method representing a fire attack from the inside of the duct first simulates temperatures within a

kitchen extract duct during normal operation followed by simulating the temperatures during a fire within the

duct. For kitchen extract ducts, the inevitable build-up of grease on the inside surfaces can lead to a severe

fire exposure and this is represented in the test method described in this part of ISO 6944. A burner assembly,

attached to a horizontal L-shaped combustion chamber, develops the heat required to obtain the

temperatures. The combustion chamber is attached to the sample kitchen extract duct assembly. The kitchen

extract duct is also L-shaped with both horizontal and vertical components.

The test method representing a fire attack from the outside of the duct exposes the kitchen extract duct to

furnace conditions defined in ISO 834-1. The test method includes provisions for assessment of the

penetration seal surrounding the kitchen extract as the duct passes through a fire resistive barrier. The test

method evaluates the structural integrity of the kitchen extract duct by having the duct restrained within the

furnace during the fire exposure.
© ISO 2009 – All rights reserved v
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INTERNATIONAL STANDARD ISO 6944-2:2009(E)
Fire containment — Elements of building construction —
Part 2:
Kitchen extract ducts

CAUTION — The attention of all persons concerned with managing and carrying out of this fire

resistance test is drawn to the fact that fire testing can be hazardous and there is a possibility that

toxic and/or harmful smoke and gases can be evolved during the test. Mechanical and operational

hazards can also arise during the construction of the test elements or structures, their testing and

disposal of test residues.

It is strongly recommended that the duct assembly be allowed to cool completely after the fire test

before dismantling to minimize the possibility of the ignition of combustible residues.

An assessment of all potential hazards and risks to health shall be made and safety precautions shall

be identified and provided. Written safety instructions shall be issued. Appropriate training shall be

given to relevant personnel. Laboratory personnel shall ensure that they follow written safety

instructions at all times.
1 Scope

This part of ISO 6944 establishes a method of test in which kitchen extract ducts are required to provide fire

resistance. The requirements are intended to limit the spread of fire from the duct when a fire occurs within the

duct and assesses the structural integrity of the duct when a fire occurs in the area surrounding the duct.

2 Normative references

The following referenced documents are indispensable for the application 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 : General requirements

ISO 6944–1:2008, Fire containment — Elements of building construction — Part 1: Ventilation ducts

ISO 13943, Fire safety — Vocabulary
3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 6944-1, ISO 13943 and the

following apply.
3.1
kitchen extract duct
exhaust duct intended for use in commercial kitchens
© ISO 2009 – All rights reserved 1
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ISO 6944-2:2009(E)
3.2
fire-resisting kitchen extract ducts

kitchen extract ducts that have been tested to this part of ISO 6944 and meet the prescribed levels of fire

resistance
4 Test equipment
4.1 Fire outside duct

The test equipment specified in ISO 6944-1 for testing duct A shall be used, except that the fan, volume flow-

measuring station and the condensing unit are not required.
4.2 Fire inside duct

4.2.1 A gas-fired premix burner assembly shall be used to supply flue gases to the test specimen.

4.2.2 The burner assembly shall be placed at the inlet of an insulated, L-shaped combustion chamber

assembly, as illustrated in Figure 1.
Key
1 kitchen extract duct 5 location of burner assembly
2 transition section, where required 6 cleanout access cover
3 combustion chamber 7 supports

4 ceramic fibre insulation on combustion chamber L to L various governing dimensions

1 6
Figure 1 — Test assembly

4.2.2.1 The minimum total length of the L-shaped insulated combustion chamber, L + L , shall be

1 2
3 700 mm.

4.2.2.2 The minimum height and width of the steel duct for the combustion chamber shall be 700 mm by

700 mm.

4.2.2.3 The minimum thickness of the ceramic fibre insulation for the combustion chamber shall be

3 3
50 mm. The density of the insulation shall be 120 kg/m ± 30 kg/m .
2 © ISO 2009 – All rights reserved
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ISO 6944-2:2009(E)

4.2.3 Combustion shall be complete within the combustion chamber assembly. The insulated combustion

chamber assembly shall be connected to the kitchen extract duct by means of bolted or clamped flanges. The

flanges shall be welded to the combustion chamber and to the kitchen extract duct.

4.2.4 For ducts whose orifice area exceeds 0,75 m , the use of flow restrictors at the exhaust end of the

kitchen extract duct to adjust the rate of the flue gases to assist in obtaining the required temperatures within

the kitchen extract duct is allowed, provided that the exhaust remains at least 75 % open.

5 Test conditions
5.1 Fire outside duct
The test conditions specified in ISO 6944-1 for testing duct A shall be used.
5.2 Fire inside duct

5.2.1 The specimen shall be tested within a laboratory having ventilation capable of maintaining the build-

up of carbon monoxide to less than 50 µl/l throughout the period of any test. The area shall be free of

extraneous drafts. The laboratory shall be constructed so that, during any one test, the room temperature in

the laboratory does not increase by more than 23 °C above the temperature recorded at the beginning of the

test.

5.2.2 The test specimen with respect to moisture content shall be representative of the condition that exists

in similar construction in buildings. The condition shall be established by storage in air having 50 % relative

humidity at 23 °C.

5.2.3 When conditioning to this level is not possible, the test shall be conducted when the dampest portion

of the test specimen has achieved an equilibrium moisture content less than that corresponding to drying in air

having 75 % relative humidity at 23 ± 3 °C.
5.2.4 Exception: The requirements of 5.2.3 are not mandatory when

⎯ an equilibrium condition is not achieved within a 12 month conditioning period; or

⎯ construction is such that drying of the interior of the test specimen is prevented by hermetic sealing of the

construction materials.
6 Instrumentation
6.1 Fire outside duct
The instrumentation specified in ISO 6944-1 for testing duct A shall be used.
6.2 Fire inside duct
6.2.1 Flue gas temperatures

6.2.1.1 The thermocouples shall be located within the L-shaped kitchen extract duct as illustrated in

Figures 2 and 3.

1) Microlitres per litre is the approximate conversion of the derogated unit “ppm.”

© ISO 2009 – All rights reserved 3
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ISO 6944-2:2009(E)
Key
1 kitchen extract duct (side view)
2 location of thermocouple grid for measuring flue-gas temperatures
Figure 2 — Thermocouple locations for measuring flue gas temperatures

6.2.1.2 Flue gas temperatures shall be determined by a thermocouple grid as illustrated in Figure 3. The

grid shall consist of four thermocouples located inside the kitchen extract duct to measure the flue gas

temperature at the mid-length of the horizontal section of the kitchen extract duct assembly; see Figure 2.

6.2.1.3 The thermocouples shall be maximum 1,0 mm, Type K or Type S Inconel-sheathed

thermocouples with tips projecting 25 + 1,5 mm from the inner ends of the support tubes as illustrated in

Figure 3.
6.2.1.4 The dimension a shall be equal to D/4 but not greater than 305 mm.
6.2.1.5 The dimension b shall be equal to W/4 but not greater than 305 mm.
6.2.2 Unexposed surface temperatures
6.2.2.1 Fixed locations

6.2.2.1.1 Temperatures on the unexposed surfaces shall be measured using thermocouples and pads in

accordance with ISO 834-1.

6.2.2.1.2 A minimum of fourteen thermocouples shall be located on the horizontal section of the test

specimen.

6.2.2.1.3 Eight thermocouples shall be symmetrically located around the perimeter of the specimen as

shown in Figures 4 and 5. None of the eight thermocouples shall be located over joints in the insulation

material. The insulation thickness shall be the minimum at these locations.

2) Inconel is an example of a suitable product available commercially. This information is given for the convenience of

users of this part of ISO 6944 and does not constitute an endorsement by ISO of this product.

4 © ISO 2009 – All rights reserved
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ISO 6944-2:2009(E)
Dimensions in millimetres
Key
1 kitchen extract duct
2 support tube for thermocouples
3 location of thermocouple tip, represented by “•”
Dimension a shall be equal to D/4 but not greater than 305 mm.
Dimension b shall be equal to W/4 but not grea
...

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