Fire-resistance tests - Elements of building construction

This part of ISO 834 specifies a test method for determining the fire resistance of various elements of
construction when subjected to standard fire exposure conditions. The test data thus obtained will permit
subsequent classification on the basis of the duration for which the performance of the tested elements under
these conditions satisfies specified criteria.

Essai de résistance au feu - Éléments de construction

La présente partie de l'ISO 834 décrit une méthode d'essai en vue de déterminer la résistance au feu de divers
éléments de construction quand ils sont soumis ŕ des conditions normalisées d'exposition au feu. Les données de
l'essai ainsi obtenues permettront d'établir ensuite une classification en fonction de la durée pendant laquelle la
performance des éléments soumis ŕ l'essai dans ces conditions satisfait aux critčres spécifiés.

Preskusi požarne odpornosti - Gradbeni elementi

General Information

Status
Published
Public Enquiry End Date
19-Nov-2021
Publication Date
26-Sep-2021
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
08-Sep-2021
Due Date
13-Nov-2021
Completion Date
27-Sep-2021

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Standards Content (sample)

SLOVENSKI STANDARD
SIST ISO 834-1:2021
01-november-2021
Preskusi požarne odpornosti - Gradbeni elementi
Fire-resistance tests - Elements of building construction
Essai de résistance au feu - Éléments de construction
Ta slovenski standard je istoveten z: ISO 834-1:1999
ICS:
13.220.50 Požarna odpornost Fire-resistance of building
gradbenih materialov in materials and elements
elementov
91.060.01 Stavbni elementi na splošno Elements of buildings in
general
SIST ISO 834-1:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ISO 834-1:2021
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SIST ISO 834-1:2021
INTERNATIONAL ISO
STANDARD 834-1
First edition
1999-09-15
Fire-resistance tests — Elements of
building construction —
Part 1:
General requirements
Essai de résistance au feu — Éléments de construction
Partie 1: Exigences générales
Reference number
ISO 834-1:1999(E)
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SIST ISO 834-1:2021
ISO 834-1:1999(E)
Contents Page

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

2 Normative reference.................................................................................................................. 1

3 Definitions................................................................................................................................. 1

4 Symbols and abbreviations ....................................................................................................... 2

5 Test equipment.......................................................................................................................... 3

6 Test conditions ........................................................................................................................ 12

7 Test specimen preparation ......................................................................................................15

8 Application of instrumentation............................................................................................... 17

9 Test procedure......................................................................................................................... 20

10 Performance criteria................................................................................................................ 22

11 Validity of the test................................................................................................................... 24

12 Expression of test results ........................................................................................................ 24

13 Test report ............................................................................................................................... 25

© ISO 1999

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any

means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher.

International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
---------------------- Page: 4 ----------------------
SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(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.

Draft International Standards adopted by the technical committees are circulated to the member

bodies for voting. Publication as International Standard requires approval by at least two-thirds

of the Member Bodies casting a vote.

International Standard ISO 834-1 was prepared by Technical Committee ISO/TC 92, Fire

safety, Subcommittee SC 2, Fire resistance.
This first edition of ISO 834-1 cancels and replaces ISO 834:1975, together with

Amendment 1:1979 and Amendment 2:1980, of which it constitutes a technical revision. The

revision has been made because of the need for more accuracy and reproducibility in the test

method. Its provisions are supplemented by the commentary material contained in part 3.

ISO 834 consists of the following parts under the general title Fire-resistance tests — Elements

of building construction:
— Part 1: General requirements
— Part 3: Commentary on test method and test data application
— Part 4: Specific requirements for loadbearing vertical separating elements
— Part 5: Specific requirements for loadbearing horizontal separating elements
— Part 6: Specific requirements for loadbearing beams
— Part 7: Specific requirements for loadbearing columns

— Part 8: Specific requirements for non-loadbearing vertical separating elements

— Part 9: Specific requirements for non-loadbearing horizontal separating elements

— Part 10: Method to determine the contribution of applied protection materials to structural

metallic elements

— Part 11: Method to assess the contribution of applied protection materials to structural

metallic elements
iii
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SIST ISO 834-1:2021
ISO 834-1:1999(E) ISO
Introduction

Significant changes with respect to ISO 834:1975 are requirements for the following:

– accuracy of measuring equipment;

– tolerances applied to the deviation of the curve of the average furnace temperature with

respect to the standard heating curve;
– pressure conditions for vertical and horizontal elements;
– specification of test load;
– conditioning;
– application of instrumentation;
– criteria respecting loadbearing capacity.

In general, the revision reflects the objective of Working Group WG 1 in providing a standard

that is arranged in logical sequence and providing for increased precision in the development

and application of the test data, as well as repeatability of the results using the same and

different equipment. It is planned to enhance the repeatability aspect by the development, in the

near future, of a precision calibration routine which will address parameters such as temperature

uniformity, pressure gradients, oxygen concentration, furnace lining materials, and others.

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SIST ISO 834-1:2021
INTERNATIONAL STANDARD ISO ISO 834-1:1999(E)
Fire-resistance tests – Elements of building construction –
Part 1:
General requirements
1Scope

This part of ISO 834 specifies a test method for determining the fire resistance of various elements of

construction when subjected to standard fire exposure conditions. The test data thus obtained will permit

subsequent classification on the basis of the duration for which the performance of the tested elements under

these conditions satisfies specified criteria.
2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this

part of ISO 834 . At the time of publication, the editions indicated were valid. All standards are subject to

revision, and parties to agreements based on this part of ISO 834 are encouraged to investigate the

possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO

maintain registers of currently valid International Standards.
ISO 13943:— , Fire safety — Vocabulary.
IEC 60584-1:1995, Thermocouples — Part 1: Reference tables.
3 Definitions

For the purposes of this part of ISO 834, the definitions given in ISO 13943 and the following definitions

apply.

3.1 actual material properties: Properties of a material determined from representative samples taken

from the specimen for the fire test according to the requirements of the concerned product standard.

3.2 calibration test
: Procedure to assess the test conditions experimentally.

3.3 deformation: Any change in dimension or shape of an element of construction due to structural

and/or thermal actions. This includes deflection, expansion or contraction of elements.

1) To be published.
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© ISO
ISO 834-1:1999(E)

3.4 element of building construction: Defined construction component, such as a wall, partition, floor,

roof, beam or column.

3.5 insulation: Ability of a separating element of building construction when exposed to fire on one side,

to restrict the temperature rise of the unexposed face to below specified levels.

: Ability of a separating element of building construction, when exposed to fire on one side,

3.6 integrity

to prevent the passage through it of flames and hot gases or the occurrence of flames on the unexposed side.

3.7 loadbearing capacity: Ability of a specimen of a loadbearing element to support its test load, where

appropriate, without exceeding specified criteria with respect to both the extent of, and rate of, deformation.

3.8 loadbearing element: An element that is intended for use in supporting an external load in a building

and maintaining this support in the event of a fire.
: Elevation at which the pressure is equal inside and outside the furnace.
3.9 neutral pressure plane

3.10 notional floor level: Assumed floor level relative to the position of the building element in service.

3.11 restraint: The constraint to expansion or rotation (induced by thermal and/or mechanical actions)

afforded by the conditions at the ends, edges or supports of a test specimen.

NOTE — Examples of different types of restraint are longitudinal, rotational and lateral.

3.12 separating element: An element that is intended for use in maintaining separation between two

adjacent areas of a building in the event of a fire.

3.13 supporting construction: That construction that may be required for the testing of some building

elements into which the test specimen is assembled, such as the wall into which a door is fitted.

: Complete assembly of the test specimen together with its supporting construction.

3.14 test construction

3.15 test specimen: Element (or part) of a building construction provided for the purpose of determining

either its fire resistance or its contribution to the fire resistance of another building element.

4Symbols
Symbol Description Unit
A area under the actual average furnace time/temperature curve
°C{min
A area under the standard time/temperature curve
°C{min
C axial contraction measured from the start of heating mm
C(t) axial contraction at time t during the test mm
rate of axial contraction, defined as: mm/min
Ct() -C(t)
( )
tt-21
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
d distance from the extreme fibre of the design compression zone to the mm
extreme fibre of the design tensile zone of the structural section of a
flexural test specimen
D deflection measured from the commencement of heating mm
D(t) deflection at time t during the test mm
D rate of deflection, defined as:
DD()tt - ( )
mm/min
( - )
h initial height of axially loaded specimen mm
L length of the clear span of the specimen mm
d percent deviation (see 6.1.2) %
t time from the commencement of heating min
T temperature within the test furnace
5 Test equipment
5.1 General

Equipment employed in the conduct of the test consists essentially of the following:

a) a specially designed furnace to subject the test specimen to the test conditions specified in the appropriate

clause;

b) control equipment to enable the temperature of the furnace to be regulated as specified in 6.1;

c) equipment to control and monitor the pressure of the hot gases within furnace as specified in 6.2;

d) a frame in which the test specimen can be erected and which can be positioned in conjunction with the

furnace so that appropriate heating, pressure and support conditions can be developed;

e) arrangement for loading and restraint of the test specimen as appropriate, including control and

monitoring of loads;

f) equipment for measuring temperature in the furnace and on the unheated face of the test specimen, and

where needed within the test specimen construction;

g) equipment for measuring the deformation of the test specimen where specified in the appropriate clauses;

h) equipment for evaluating test specimen integrity and for establishing compliance with the performance

criteria described in clause 10 and for establishing the elapsed time.
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
5.2 Furnace

The test furnaces shall be designed to employ liquid or gaseous fuels and shall be capable of

a) heating of vertical or horizontal separating elements on one face; or
b) heating of columns on all sides; or
c) heating of walls on more than one side; or
d) heating of beams on three or four sides, as appropriate.

NOTE — Furnaces may be designed so that assemblies of more than one element can be tested simultaneously, provided all the

requirements for each individual element can be complied with.

The furnace linings shall consist of materials with densities less than 1 000 kg/m . Such lining materials

shall have a minimum thickness of 50 mm and shall constitute at least 70 % of the internally exposed surface

of the furnace.
5.3 Loading equipment

The loading equipment shall be capable of subjecting test specimens to the level of loading determined

according to 6.4. The load may be applied hydraulically, mechanically or by the use of weights.

The loading equipment shall be able to simulate conditions of uniform loading, point loading, concentric

loading or eccentric loading, as appropriate for the test construction. The loading equipment shall also be

capable of maintaining the test load at a constant value (to within – 5 % of the required value) without

changing its distribution for the duration of the loadbearing capacity period. The equipment shall be capable

of following the maximum deformation and the rate of deformation of the test specimen for the duration of

the test.

The loading equipment shall not significantly influence the heat transfer through the specimen nor impede

the use of the thermocouple insulating pads. It shall not interfere with the measurement of surface

temperature and/or deformation and shall permit general observation of the unexposed face. The total area

of the contact points between the loading equipment and the test specimen surface shall not exceed 10 % of

the total area of the surface of a horizontal test specimen.

Where loading has to be maintained after the end of heating, provision shall be made for such maintenance.

5.4 Restraint and support frames

Special frames or other means shall be used to reproduce the boundary and support conditions appropriate

for the test specimens as specified in 6.5.
5.5 Instrumentation
5.5.1 Temperature
5.5.1.1 Furnace thermocouples

The furnace thermocouples shall be plate thermometers which comprise an assembly of a folded steel plate,

the thermocouple fixed to it and containing insulation material. The measuring and recording equipment

shall be capable of operating within the limits specified in 5.6.
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)

The plate part shall be constructed from (150 ± 1) mm long by (100 ± 1) mm wide by (0,7 ± 0,1) mm thick

nickel alloy sheet strips folded to the design as shown in figure 1.

The measuring junction shall consist of nickel chromium/nickel aluminium (type K) wire as defined in

IEC 60584-1, contained within mineral insulation in a heat-resisting steel alloy sheath of nominal diameter

1 mm, the hot junctions being electrically insulated from the sheath. The thermocouple hot junction shall be

fixed to the geometric centre of the plate in the position shown in figure 1 by a small steel strip made from

the same material as the plate. The steel strip can be welded to the plate or may be screwed to it to facilitate

replacement of the thermocouple. The strip shall be approximately 18 mm by 6 mm if it is spot welded to the

plate, and nominally 25 mm by 6 mm if it is to be screwed to the plate. The screw shall be 2 mm in diameter.

The assembly of plate and thermocouple shall be fitted with a pad of inorganic insulation material nominally

(97 ± 1) mm by (97 ± 1) mm by (10 ± 1) mm thick, density (280 ± 30) kg/m .

Before the plate thermometers are first used, the complete plate thermometer shall be aged by immersing in

a pre-heated oven at 1 000 °C for 1 h.

NOTE — Exposure in a fire resistance furnace for 90 min under the standard temperature/time curve is considered to be an

acceptable alternative to using an oven.

When a plate thermometer is used more than once, a log of its use shall be maintained indicating, for each

use, the checks made and duration of use. The thermocouple and the insulation pad shall be replaced after

50 h exposure in the furnace.
5.5.1.2 Unexposed surface thermocouples

The temperature of the unexposed surface of the test specimen shall be measured by means of disc

thermocouples of the type shown in figure 2. In order to provide a good thermal contact, thermocouple

wires, 0,5 mm in diameter, shall be soldered or welded to a 0,2 mm thick by 12 mm diameter copper disc.

Each thermocouple shall be covered with a 30 mm x 30 mm x 2,0 mm – 0,5 mm thick inorganic insulating

pad, unless specified otherwise in the standards for specific elements. The pad material shall have a density

3 3

of 900 kg/m – 100 kg/m . The measuring and recording equipment shall be capable of operating within the

limits specified in 5.6.

The insulating pad shall be bonded to the surface of the test specimen, with no adhesive between the copper

disc and the specimen surface or between the copper disc and the insulating pad.
5.5.1.3 Roving thermocouples

One or more roving thermocouples of the design shown in figure 3 or alternative temperature-measuring

devices which can be shown to have at least the accuracy and a response time equal to or less than the design

illustrated by figure 3 shall be available to measure the unexposed surface temperature during a test in

positions where higher temperatures are suspected. The measuring junction of the thermocouple consists of

1,0 mm diameter thermocouple wires soldered or welded to a 12 mm diameter, 0,5 mm thick copper disc.

The thermocouple assembly shall be provided with a handle so that it can be applied over any point on the

unexposed surface of the test specimen.
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1 Sheathed thermocouple with insulated hot junction
2 Spot-welded or screwed steel strip
3 Hot junction of thermocouple
4 Insulation material
5 Nickel alloy strip (0,7 ± 0,1) mm thick
6 Face A
Figure 1 — Illustration of plate thermometer
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1 Thermocouple wire, of 0,5 mm diameter
2 Copper disc, 0,2 mm thick
a) Copper disc measuring junction
Key
1) Cuts to allow pad to be positioned over copper disc
2) Alternative cut location
b) Copper disc and insulating pad
Figure 2 — Unexposed surface thermocouple and insulating pad
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1) Heat-resistant steel support tube, of 13 mm diameter
2) Twin-bore ceramic insulator, of 8 mm diameter
3) Thermocouple wire, of 1,0 mm diameter
4) Copper disc, 12 mm in diameter,0,5 mm thick
Figure 3 — Roving thermocouple assembly
5.5.1.4 Internal thermocouples

When information concerning the internal temperature of a test specimen or particular component is

required, it shall be obtained by means of thermocouples having characteristics appropriate to the range of

temperatures to be measured as well as being suitable for the type of materials in the test specimen.

5.5.1.5 Ambient-temperature thermocouples

A thermocouple shall be used to indicate the ambient temperature within the laboratory in the vicinity of the

test specimen both prior to and during the test period. The thermocouple shall be nominally of 3 mm

diameter, mineral insulated, stainless-steel sheathed type K, as defined in IEC 60584-1. The measuring

junction shall be protected from radiated heat and draughts.
5.5.2 Pressure

The pressure in the furnace shall be measured by means of one of the designs of sensors shown in figure 4.

The measuring and recording equipment shall be capable of operating within the limits specified in 5.6.

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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1) To pressure transducer
2) Open
3) Stainless-steel tube (inside diameter 5 mm to 10 mm)
a) Type 1 - "T" shaped sensor
Key
1) Holes, of 3,0 mm diameter
2) Holes, of 3,0 mm diameter, spaced 40° apart around the pipe
3) Welded end
4) Stainless-steel pipe
b) Type 2 - Tube sensor
Figure 4 — Pressure-sensing heads
5.5.3 Load

When using weights, no further measurement of load in a test is needed. The loads applied by hydraulic

loading systems shall be measured by means of a load cell or other relevant equipment having the same

accuracy or by monitoring the hydraulic pressure at an appropriate point. The measuring and recording

equipment shall be capable of operating within the limits specified in 5.6.
5.5.4 Deformation

Deformation measurements can be made by using equipment employing mechanical, optical or electrical

techniques. Where such equipment is used in relation to performance criteria (e.g. measurements of

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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)

deflection or contraction), it shall be capable of operating at a frequency of at least one reading per minute.

All necessary precautions shall be taken to prevent any drift in the sensor readings due to heating.

5.5.5 Integrity
5.5.5.1 Cotton pad

Unless specified otherwise in the standards for specific elements, the cotton pad used in the measurement of

integrity shall consist of new, undyed and soft cotton fibres without other added fibres, 20 mm thick 3 100

mm square, and shall weigh between 3 g and 4 g. It shall be conditioned prior to use by drying in an oven at

100°C – 5°C for at least 30 min. After drying it may be stored in a desiccator or other moisture-proof

container until use. For use, it shall be mounted in a wire frame, as shown in figure 5, provided with a

handle.
Dimensions in millimetres
Key
1) Hinge
2) Handle of suitable length
3) Supporting steel wire of 0,5 mm diameter
4) Hinged lid with latch
5) Framework of steel wire of 1,5 mm diameter
Figure 5 — Cotton pad holder
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
5.5.5.2 Gap gauge

Two types of gap gauge, as shown in figure 6, shall be available for the measurement of integrity. They shall

be made of cylindrical stainless steel rod of 6 mm – 0,1 mm and 25 mm – 0,2 mm diameter. They shall be

provided with insulated handles of suitable length.
Dimensions in millimetres
Key
1) Stainless steel rod
2) Insulated handle
Figure 6 — Gap gauges
5.6 Accuracy of measuring equipment

For conducting fire tests, the measuring equipment shall meet the following levels of accuracy:

a) temperature measurement: furnace
– 15°C;
ambient and unexposed face
– 4°C;
other
– 10°C;
b) pressure measurement:
– 2 Pa;
c) load level:
– 2,5 % of test load;
d) axial contraction or expansion measurement:
– 0,5 mm;
e) other deformation measurements:
– 2 mm;
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
6 Test conditions
6.1 Furnace temperature
6.1.1 Heating curve

The average temperature of the furnace, as derived from the thermocouples specified in 5.5.1.1, shall be

monitored and controlled such that it follows the relationship (see figure 7):
T = 345 log (8t + 1) + 20
where
T is the average furnace temperature, in degrees Celsius;
t is the time, in minutes.
Key
1 Furnace temperature versus time
Figure 7 — Standard time/temperature curve
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SIST ISO 834-1:2021
© ISO
ISO 834-1:1999(E)
6.1.2 Tolerances

The percent deviation d in the area of the curve of the average temperature recorded by the specified

furnace thermocouples versus time from the area of the standard time/temperature curve shall be within

a) d £ 15 % for 5 < t £ 10;
for 10 < t £ 30;
b) d = 15 - 0,5 (t - 10) %
for 30 < t £ 60;
c) d = 5 - 0,083 (t - 30) %
d) d = 2,5 % for t > 60;
AA-s
= ·100
where
d is the percent deviation;
A is the area under the actual average furnace time/temperature curve;
A is the area under the standard time/temperature curve;
t is the time, in minutes.

All areas shall be computed by the same method, i.e. by the summation of areas at intervals not exceeding

1 min for a) and 5 min for b), c) and d) and shall be calculated from time zero. The start of the test is

described in 9.3.

At any time after the first 10 min of test, the temperature recorded by any thermocouple in the furnace shall

not differ from the corresponding temperature of the standard time/temperature curve by more than 100 °C.

For test specimens incorporating a significant amount of combustible material, the deviation may be

exceeded for a period not in excess of 10 min provided that such excess deviation is clearly identified as

being associated with the sudden ignition of significant quantities of combustible materials increasing the

average furnace temperature.
6.2 Furnace pressure differential
6.2.1 General

A linear pressure gradient exists over the height of furnace, and although the gradient will vary slightly as a

function of the furnace temperature, a mean value of 8 Pa per meter height may be assumed in assessing the

furnace pressure conditions.

The value of the furnace pressure at a specified height shall be the nominal mean value, disregarding

fluctuations of pressure associated with turbulence, etc., and shall be established relative to the pressure

outside the furnace at the same height. The mean value of the furnace control pressure shall be monitored in

accordance with 9.4.2 and controlled for the first 5 min from the commencement of the test to – 5 Pa and for

10 min to – 3 Pa.
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ISO 834-1:1999(E)
6.2.2 Vertical elements

The furnace shall be operated such that a pressure of zero is established at a height of 500 mm above the

notional floor level. However the pressure at the top of the test specimen shall not be greater than 20 Pa,

and the height of the neutral pressure plane shall be adjusted accordingly.
6.2.3 Horizontal elements

The furnace shall be operated such that a pressure of 20 Pa is established at a position 100 mm below the

underside of the test specimen or the notional ceiling level when testing beams.
6.3 Loading

The testing laboratory shall indicate clearly the basis on which the test load has been determined. The test

load can be determined on the basis of one of the following:

a) the actual material properties of the test specimen and a design method specified in a recognized

structural code;

b) the characteristic material properties of the test specimen and a design method specified in a

recognized structural code; wherever possible, the relationship between the loadbearing capacities

determined on the basis of the characteristic and the actual material properties shall be given;

c) a service load given in a code of practice on the use of the construction or indicated by the sponsor

for a particular use. The relationship between the service loadbearing capacity and the load determined

on the basis of the distribution of material properties one can expect for the test specimen and the

characteristic material properties assigned to the test specimen shall be given or shall be experimentally

determined.
6.4 Restraint/Boundary conditions

The test specimen shall be mounted in a special support and restraint frame in such a way that the methods

adopted for supporting the ends or the sides during the test simulate, in a representative and definable

manner, those which would be applied to a similar element in service.

The boundary conditions may provide for restraint against expansion, contraction or rotation. Alternatively

the boundary conditions may offer freedom for deformation to occur. A test specimen may be tested with

one or other of these boundary conditions applied to all or only some of its edges. The choice of the

conditions shall be made on the basis of a careful analysis of the conditions that apply in practice.

Test specimens representative of elements with uncertain or variable boundary conditions in service, shall be

supported at the edges or at the ends in such a manner as to provide conservative results.

If restraint is applied during the test, then the restraint conditions shall be described with regard to the free

movement of the element prior to encountering resistance to expansion, contraction or rotation. As far as

possible, the extern
...

INTERNATIONAL ISO
STANDARD 834-1
First edition
1999-09-15
Fire-resistance tests — Elements of
building construction —
Part 1:
General requirements
Essai de résistance au feu — Éléments de construction
Partie 1: Exigences générales
Reference number
ISO 834-1:1999(E)
---------------------- Page: 1 ----------------------
ISO 834-1:1999(E)
Contents Page

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

2 Normative reference.................................................................................................................. 1

3 Definitions................................................................................................................................. 1

4 Symbols and abbreviations ....................................................................................................... 2

5 Test equipment.......................................................................................................................... 3

6 Test conditions ........................................................................................................................ 12

7 Test specimen preparation ......................................................................................................15

8 Application of instrumentation............................................................................................... 17

9 Test procedure......................................................................................................................... 20

10 Performance criteria................................................................................................................ 22

11 Validity of the test................................................................................................................... 24

12 Expression of test results ........................................................................................................ 24

13 Test report ............................................................................................................................... 25

© ISO 1999

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any

means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher.

International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
---------------------- Page: 2 ----------------------
© ISO
ISO 834-1:1999(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.

Draft International Standards adopted by the technical committees are circulated to the member

bodies for voting. Publication as International Standard requires approval by at least two-thirds

of the Member Bodies casting a vote.

International Standard ISO 834-1 was prepared by Technical Committee ISO/TC 92, Fire

safety, Subcommittee SC 2, Fire resistance.
This first edition of ISO 834-1 cancels and replaces ISO 834:1975, together with

Amendment 1:1979 and Amendment 2:1980, of which it constitutes a technical revision. The

revision has been made because of the need for more accuracy and reproducibility in the test

method. Its provisions are supplemented by the commentary material contained in part 3.

ISO 834 consists of the following parts under the general title Fire-resistance tests — Elements

of building construction:
— Part 1: General requirements
— Part 3: Commentary on test method and test data application
— Part 4: Specific requirements for loadbearing vertical separating elements
— Part 5: Specific requirements for loadbearing horizontal separating elements
— Part 6: Specific requirements for loadbearing beams
— Part 7: Specific requirements for loadbearing columns

— Part 8: Specific requirements for non-loadbearing vertical separating elements

— Part 9: Specific requirements for non-loadbearing horizontal separating elements

— Part 10: Method to determine the contribution of applied protection materials to structural

metallic elements

— Part 11: Method to assess the contribution of applied protection materials to structural

metallic elements
iii
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ISO 834-1:1999(E) ISO
Introduction

Significant changes with respect to ISO 834:1975 are requirements for the following:

– accuracy of measuring equipment;

– tolerances applied to the deviation of the curve of the average furnace temperature with

respect to the standard heating curve;
– pressure conditions for vertical and horizontal elements;
– specification of test load;
– conditioning;
– application of instrumentation;
– criteria respecting loadbearing capacity.

In general, the revision reflects the objective of Working Group WG 1 in providing a standard

that is arranged in logical sequence and providing for increased precision in the development

and application of the test data, as well as repeatability of the results using the same and

different equipment. It is planned to enhance the repeatability aspect by the development, in the

near future, of a precision calibration routine which will address parameters such as temperature

uniformity, pressure gradients, oxygen concentration, furnace lining materials, and others.

---------------------- Page: 4 ----------------------
INTERNATIONAL STANDARD ISO ISO 834-1:1999(E)
Fire-resistance tests – Elements of building construction –
Part 1:
General requirements
1Scope

This part of ISO 834 specifies a test method for determining the fire resistance of various elements of

construction when subjected to standard fire exposure conditions. The test data thus obtained will permit

subsequent classification on the basis of the duration for which the performance of the tested elements under

these conditions satisfies specified criteria.
2 Normative references

The following standards contain provisions which, through reference in this text, constitute provisions of this

part of ISO 834 . At the time of publication, the editions indicated were valid. All standards are subject to

revision, and parties to agreements based on this part of ISO 834 are encouraged to investigate the

possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO

maintain registers of currently valid International Standards.
ISO 13943:— , Fire safety — Vocabulary.
IEC 60584-1:1995, Thermocouples — Part 1: Reference tables.
3 Definitions

For the purposes of this part of ISO 834, the definitions given in ISO 13943 and the following definitions

apply.

3.1 actual material properties: Properties of a material determined from representative samples taken

from the specimen for the fire test according to the requirements of the concerned product standard.

3.2 calibration test
: Procedure to assess the test conditions experimentally.

3.3 deformation: Any change in dimension or shape of an element of construction due to structural

and/or thermal actions. This includes deflection, expansion or contraction of elements.

1) To be published.
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© ISO
ISO 834-1:1999(E)

3.4 element of building construction: Defined construction component, such as a wall, partition, floor,

roof, beam or column.

3.5 insulation: Ability of a separating element of building construction when exposed to fire on one side,

to restrict the temperature rise of the unexposed face to below specified levels.

: Ability of a separating element of building construction, when exposed to fire on one side,

3.6 integrity

to prevent the passage through it of flames and hot gases or the occurrence of flames on the unexposed side.

3.7 loadbearing capacity: Ability of a specimen of a loadbearing element to support its test load, where

appropriate, without exceeding specified criteria with respect to both the extent of, and rate of, deformation.

3.8 loadbearing element: An element that is intended for use in supporting an external load in a building

and maintaining this support in the event of a fire.
: Elevation at which the pressure is equal inside and outside the furnace.
3.9 neutral pressure plane

3.10 notional floor level: Assumed floor level relative to the position of the building element in service.

3.11 restraint: The constraint to expansion or rotation (induced by thermal and/or mechanical actions)

afforded by the conditions at the ends, edges or supports of a test specimen.

NOTE — Examples of different types of restraint are longitudinal, rotational and lateral.

3.12 separating element: An element that is intended for use in maintaining separation between two

adjacent areas of a building in the event of a fire.

3.13 supporting construction: That construction that may be required for the testing of some building

elements into which the test specimen is assembled, such as the wall into which a door is fitted.

: Complete assembly of the test specimen together with its supporting construction.

3.14 test construction

3.15 test specimen: Element (or part) of a building construction provided for the purpose of determining

either its fire resistance or its contribution to the fire resistance of another building element.

4Symbols
Symbol Description Unit
A area under the actual average furnace time/temperature curve
°C{min
A area under the standard time/temperature curve
°C{min
C axial contraction measured from the start of heating mm
C(t) axial contraction at time t during the test mm
rate of axial contraction, defined as: mm/min
Ct()Ct -( )
(tt-)21
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© ISO
ISO 834-1:1999(E)
d distance from the extreme fibre of the design compression zone to the mm
extreme fibre of the design tensile zone of the structural section of a
flexural test specimen
D deflection measured from the commencement of heating mm
D(t) deflection at time t during the test mm
D rate of deflection, defined as:
DD()tt - ( )
mm/min
( - )
h initial height of axially loaded specimen mm
L length of the clear span of the specimen mm
d percent deviation (see 6.1.2) %
t time from the commencement of heating min
T temperature within the test furnace
5 Test equipment
5.1 General

Equipment employed in the conduct of the test consists essentially of the following:

a) a specially designed furnace to subject the test specimen to the test conditions specified in the appropriate

clause;

b) control equipment to enable the temperature of the furnace to be regulated as specified in 6.1;

c) equipment to control and monitor the pressure of the hot gases within furnace as specified in 6.2;

d) a frame in which the test specimen can be erected and which can be positioned in conjunction with the

furnace so that appropriate heating, pressure and support conditions can be developed;

e) arrangement for loading and restraint of the test specimen as appropriate, including control and

monitoring of loads;

f) equipment for measuring temperature in the furnace and on the unheated face of the test specimen, and

where needed within the test specimen construction;

g) equipment for measuring the deformation of the test specimen where specified in the appropriate clauses;

h) equipment for evaluating test specimen integrity and for establishing compliance with the performance

criteria described in clause 10 and for establishing the elapsed time.
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© ISO
ISO 834-1:1999(E)
5.2 Furnace

The test furnaces shall be designed to employ liquid or gaseous fuels and shall be capable of

a) heating of vertical or horizontal separating elements on one face; or
b) heating of columns on all sides; or
c) heating of walls on more than one side; or
d) heating of beams on three or four sides, as appropriate.

NOTE — Furnaces may be designed so that assemblies of more than one element can be tested simultaneously, provided all the

requirements for each individual element can be complied with.

The furnace linings shall consist of materials with densities less than 1 000 kg/m . Such lining materials

shall have a minimum thickness of 50 mm and shall constitute at least 70 % of the internally exposed surface

of the furnace.
5.3 Loading equipment

The loading equipment shall be capable of subjecting test specimens to the level of loading determined

according to 6.4. The load may be applied hydraulically, mechanically or by the use of weights.

The loading equipment shall be able to simulate conditions of uniform loading, point loading, concentric

loading or eccentric loading, as appropriate for the test construction. The loading equipment shall also be

capable of maintaining the test load at a constant value (to within – 5 % of the required value) without

changing its distribution for the duration of the loadbearing capacity period. The equipment shall be capable

of following the maximum deformation and the rate of deformation of the test specimen for the duration of

the test.

The loading equipment shall not significantly influence the heat transfer through the specimen nor impede

the use of the thermocouple insulating pads. It shall not interfere with the measurement of surface

temperature and/or deformation and shall permit general observation of the unexposed face. The total area

of the contact points between the loading equipment and the test specimen surface shall not exceed 10 % of

the total area of the surface of a horizontal test specimen.

Where loading has to be maintained after the end of heating, provision shall be made for such maintenance.

5.4 Restraint and support frames

Special frames or other means shall be used to reproduce the boundary and support conditions appropriate

for the test specimens as specified in 6.5.
5.5 Instrumentation
5.5.1 Temperature
5.5.1.1 Furnace thermocouples

The furnace thermocouples shall be plate thermometers which comprise an assembly of a folded steel plate,

the thermocouple fixed to it and containing insulation material. The measuring and recording equipment

shall be capable of operating within the limits specified in 5.6.
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© ISO
ISO 834-1:1999(E)

The plate part shall be constructed from (150 ± 1) mm long by (100 ± 1) mm wide by (0,7 ± 0,1) mm thick

nickel alloy sheet strips folded to the design as shown in figure 1.

The measuring junction shall consist of nickel chromium/nickel aluminium (type K) wire as defined in

IEC 60584-1, contained within mineral insulation in a heat-resisting steel alloy sheath of nominal diameter

1 mm, the hot junctions being electrically insulated from the sheath. The thermocouple hot junction shall be

fixed to the geometric centre of the plate in the position shown in figure 1 by a small steel strip made from

the same material as the plate. The steel strip can be welded to the plate or may be screwed to it to facilitate

replacement of the thermocouple. The strip shall be approximately 18 mm by 6 mm if it is spot welded to the

plate, and nominally 25 mm by 6 mm if it is to be screwed to the plate. The screw shall be 2 mm in diameter.

The assembly of plate and thermocouple shall be fitted with a pad of inorganic insulation material nominally

(97 ± 1) mm by (97 ± 1) mm by (10 ± 1) mm thick, density (280 ± 30) kg/m .

Before the plate thermometers are first used, the complete plate thermometer shall be aged by immersing in

a pre-heated oven at 1 000 °C for 1 h.

NOTE — Exposure in a fire resistance furnace for 90 min under the standard temperature/time curve is considered to be an

acceptable alternative to using an oven.

When a plate thermometer is used more than once, a log of its use shall be maintained indicating, for each

use, the checks made and duration of use. The thermocouple and the insulation pad shall be replaced after

50 h exposure in the furnace.
5.5.1.2 Unexposed surface thermocouples

The temperature of the unexposed surface of the test specimen shall be measured by means of disc

thermocouples of the type shown in figure 2. In order to provide a good thermal contact, thermocouple

wires, 0,5 mm in diameter, shall be soldered or welded to a 0,2 mm thick by 12 mm diameter copper disc.

Each thermocouple shall be covered with a 30 mm x 30 mm x 2,0 mm – 0,5 mm thick inorganic insulating

pad, unless specified otherwise in the standards for specific elements. The pad material shall have a density

3 3

of 900 kg/m – 100 kg/m . The measuring and recording equipment shall be capable of operating within the

limits specified in 5.6.

The insulating pad shall be bonded to the surface of the test specimen, with no adhesive between the copper

disc and the specimen surface or between the copper disc and the insulating pad.
5.5.1.3 Roving thermocouples

One or more roving thermocouples of the design shown in figure 3 or alternative temperature-measuring

devices which can be shown to have at least the accuracy and a response time equal to or less than the design

illustrated by figure 3 shall be available to measure the unexposed surface temperature during a test in

positions where higher temperatures are suspected. The measuring junction of the thermocouple consists of

1,0 mm diameter thermocouple wires soldered or welded to a 12 mm diameter, 0,5 mm thick copper disc.

The thermocouple assembly shall be provided with a handle so that it can be applied over any point on the

unexposed surface of the test specimen.
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© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1 Sheathed thermocouple with insulated hot junction
2 Spot-welded or screwed steel strip
3 Hot junction of thermocouple
4 Insulation material
5 Nickel alloy strip (0,7 ± 0,1) mm thick
6 Face A
Figure 1 — Illustration of plate thermometer
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© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1 Thermocouple wire, of 0,5 mm diameter
2 Copper disc, 0,2 mm thick
a) Copper disc measuring junction
Key
1) Cuts to allow pad to be positioned over copper disc
2) Alternative cut location
b) Copper disc and insulating pad
Figure 2 — Unexposed surface thermocouple and insulating pad
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© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1) Heat-resistant steel support tube, of 13 mm diameter
2) Twin-bore ceramic insulator, of 8 mm diameter
3) Thermocouple wire, of 1,0 mm diameter
4) Copper disc, 12 mm in diameter,0,5 mm thick
Figure 3 — Roving thermocouple assembly
5.5.1.4 Internal thermocouples

When information concerning the internal temperature of a test specimen or particular component is

required, it shall be obtained by means of thermocouples having characteristics appropriate to the range of

temperatures to be measured as well as being suitable for the type of materials in the test specimen.

5.5.1.5 Ambient-temperature thermocouples

A thermocouple shall be used to indicate the ambient temperature within the laboratory in the vicinity of the

test specimen both prior to and during the test period. The thermocouple shall be nominally of 3 mm

diameter, mineral insulated, stainless-steel sheathed type K, as defined in IEC 60584-1. The measuring

junction shall be protected from radiated heat and draughts.
5.5.2 Pressure

The pressure in the furnace shall be measured by means of one of the designs of sensors shown in figure 4.

The measuring and recording equipment shall be capable of operating within the limits specified in 5.6.

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© ISO
ISO 834-1:1999(E)
Dimensions in millimetres
Key
1) To pressure transducer
2) Open
3) Stainless-steel tube (inside diameter 5 mm to 10 mm)
a) Type 1 - "T" shaped sensor
Key
1) Holes, of 3,0 mm diameter
2) Holes, of 3,0 mm diameter, spaced 40° apart around the pipe
3) Welded end
4) Stainless-steel pipe
b) Type 2 - Tube sensor
Figure 4 — Pressure-sensing heads
5.5.3 Load

When using weights, no further measurement of load in a test is needed. The loads applied by hydraulic

loading systems shall be measured by means of a load cell or other relevant equipment having the same

accuracy or by monitoring the hydraulic pressure at an appropriate point. The measuring and recording

equipment shall be capable of operating within the limits specified in 5.6.
5.5.4 Deformation

Deformation measurements can be made by using equipment employing mechanical, optical or electrical

techniques. Where such equipment is used in relation to performance criteria (e.g. measurements of

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© ISO
ISO 834-1:1999(E)

deflection or contraction), it shall be capable of operating at a frequency of at least one reading per minute.

All necessary precautions shall be taken to prevent any drift in the sensor readings due to heating.

5.5.5 Integrity
5.5.5.1 Cotton pad

Unless specified otherwise in the standards for specific elements, the cotton pad used in the measurement of

integrity shall consist of new, undyed and soft cotton fibres without other added fibres, 20 mm thick 3 100

mm square, and shall weigh between 3 g and 4 g. It shall be conditioned prior to use by drying in an oven at

100°C – 5°C for at least 30 min. After drying it may be stored in a desiccator or other moisture-proof

container until use. For use, it shall be mounted in a wire frame, as shown in figure 5, provided with a

handle.
Dimensions in millimetres
Key
1) Hinge
2) Handle of suitable length
3) Supporting steel wire of 0,5 mm diameter
4) Hinged lid with latch
5) Framework of steel wire of 1,5 mm diameter
Figure 5 — Cotton pad holder
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© ISO
ISO 834-1:1999(E)
5.5.5.2 Gap gauge

Two types of gap gauge, as shown in figure 6, shall be available for the measurement of integrity. They shall

be made of cylindrical stainless steel rod of 6 mm – 0,1 mm and 25 mm – 0,2 mm diameter. They shall be

provided with insulated handles of suitable length.
Dimensions in millimetres
Key
1) Stainless steel rod
2) Insulated handle
Figure 6 — Gap gauges
5.6 Accuracy of measuring equipment

For conducting fire tests, the measuring equipment shall meet the following levels of accuracy:

a) temperature measurement: furnace
– 15°C;
ambient and unexposed face
– 4°C;
other
– 10°C;
b) pressure measurement:
– 2 Pa;
c) load level:
– 2,5 % of test load;
d) axial contraction or expansion measurement:
– 0,5 mm;
e) other deformation measurements:
– 2 mm;
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© ISO
ISO 834-1:1999(E)
6 Test conditions
6.1 Furnace temperature
6.1.1 Heating curve

The average temperature of the furnace, as derived from the thermocouples specified in 5.5.1.1, shall be

monitored and controlled such that it follows the relationship (see figure 7):
T = 345 log (8t + 1) + 20
where
T is the average furnace temperature, in degrees Celsius;
t is the time, in minutes.
Key
1 Furnace temperature versus time
Figure 7 — Standard time/temperature curve
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© ISO
ISO 834-1:1999(E)
6.1.2 Tolerances

The percent deviation d in the area of the curve of the average temperature recorded by the specified

furnace thermocouples versus time from the area of the standard time/temperature curve shall be within

a) d £ 15 % for 5 < t £ 10;
for 10 < t £ 30;
b) d = 15 - 0,5 (t - 10) %
for 30 < t £ 60;
c) d = 5 - 0,083 (t - 30) %
d) d = 2,5 % for t > 60;
AA-s
= ·100
where
d is the percent deviation;
A is the area under the actual average furnace time/temperature curve;
A is the area under the standard time/temperature curve;
t is the time, in minutes.

All areas shall be computed by the same method, i.e. by the summation of areas at intervals not exceeding

1 min for a) and 5 min for b), c) and d) and shall be calculated from time zero. The start of the test is

described in 9.3.

At any time after the first 10 min of test, the temperature recorded by any thermocouple in the furnace shall

not differ from the corresponding temperature of the standard time/temperature curve by more than 100 °C.

For test specimens incorporating a significant amount of combustible material, the deviation may be

exceeded for a period not in excess of 10 min provided that such excess deviation is clearly identified as

being associated with the sudden ignition of significant quantities of combustible materials increasing the

average furnace temperature.
6.2 Furnace pressure differential
6.2.1 General

A linear pressure gradient exists over the height of furnace, and although the gradient will vary slightly as a

function of the furnace temperature, a mean value of 8 Pa per meter height may be assumed in assessing the

furnace pressure conditions.

The value of the furnace pressure at a specified height shall be the nominal mean value, disregarding

fluctuations of pressure associated with turbulence, etc., and shall be established relative to the pressure

outside the furnace at the same height. The mean value of the furnace control pressure shall be monitored in

accordance with 9.4.2 and controlled for the first 5 min from the commencement of the test to – 5 Pa and for

10 min to – 3 Pa.
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© ISO
ISO 834-1:1999(E)
6.2.2 Vertical elements

The furnace shall be operated such that a pressure of zero is established at a height of 500 mm above the

notional floor level. However the pressure at the top of the test specimen shall not be greater than 20 Pa,

and the height of the neutral pressure plane shall be adjusted accordingly.
6.2.3 Horizontal elements

The furnace shall be operated such that a pressure of 20 Pa is established at a position 100 mm below the

underside of the test specimen or the notional ceiling level when testing beams.
6.3 Loading

The testing laboratory shall indicate clearly the basis on which the test load has been determined. The test

load can be determined on the basis of one of the following:

a) the actual material properties of the test specimen and a design method specified in a recognized

structural code;

b) the characteristic material properties of the test specimen and a design method specified in a

recognized structural code; wherever possible, the relationship between the loadbearing capacities

determined on the basis of the characteristic and the actual material properties shall be given;

c) a service load given in a code of practice on the use of the construction or indicated by the sponsor

for a particular use. The relationship between the service loadbearing capacity and the load determined

on the basis of the distribution of material properties one can expect for the test specimen and the

characteristic material properties assigned to the test specimen shall be given or shall be experimentally

determined.
6.4 Restraint/Boundary conditions

The test specimen shall be mounted in a special support and restraint frame in such a way that the methods

adopted for supporting the ends or the sides during the test simulate, in a representative and definable

manner, those which would be applied to a similar element in service.

The boundary conditions may provide for restraint against expansion, contraction or rotation. Alternatively

the boundary conditions may offer freedom for deformation to occur. A test specimen may be tested with

one or other of these boundary conditions applied to all or only some of its edges. The choice of the

conditions shall be made on the basis of a careful analysis of the conditions that apply in practice.

Test specimens representative of elements with uncertain or variable boundary conditions in service, shall be

supported at the edges or at the ends in such a manner as to provide conservative results.

If restraint is applied during the test, then the restraint conditions shall be described with regard to the free

movement of the element prior to encountering resistance to expansion, contraction or rotation. As far as

possible, the external forces and moments which are transmitted to the element by restraint during the test

shall be recorded.
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© ISO
ISO 834-1:1999(E)
6.5 Ambient conditions

The furnace should be installed in a laboratory of sufficient size to prevent the ambient air temperature in

the vicinity of a separating element increasing by more than 10 °C above the initial temperature whilst the

test specimen is complying with the insulation criterion. The laboratory atmosphere shall be virtually

draught-free. The ambient air temperature shall be 20 °C – 10 °C at the commencement of the test and it

shall be monitored at a distance of 1,0 m – 0,5 m from the unexposed face under conditions such that the

sensor is not affected by thermal radiation from the test specimen and/or furnace (particularly in the case of

an element which only needs to satisfy the integrity criteria).
6.6 Deviation from specified test conditions

Should the conditions of furnace temperature, furnace pressure or ambient temperature which are achieved

during the test represen
...

NORME ISO
INTERNATIONALE 834-1
Première édition
1999-09-15
Essai de résistance au feu — Éléments de
construction —
Partie 1:
Exigences générales
Fire-resistance tests — Elements of building construction
Part 1: General requirements
Numéro de référence
ISO 834-1:1999(F)
---------------------- Page: 1 ----------------------
ISO 834-1:1999(F)
Sommaire Page

1 Domaine d’application ............................................................................................................................................1

2 Références normatives ...........................................................................................................................................1

3 Définitions ................................................................................................................................................................1

4 Symboles..................................................................................................................................................................2

5 Matériel d'essai ........................................................................................................................................................3

6 Conditions d'essai .................................................................................................................................................11

7 Préparation des éprouvettes d'essai ...................................................................................................................14

8 Emplacement des instruments.............................................................................................................................15

9 Mode opératoire.....................................................................................................................................................18

10 Critères de performance .....................................................................................................................................20

11 Validité de l'essai .................................................................................................................................................21

12 Expression des résultats d'essai .......................................................................................................................21

13 Rapport d'essai ....................................................................................................................................................22

© ISO 1999

Droits de reproduction réservés. Sauf prescription différente, aucune partie de cette publication ne peut être reproduite ni utilisée sous quelque

forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie et les microfilms, sans l'accord écrit de l'éditeur.

Organisation internationale de normalisation
Case postale 56 • CH-1211 Genève 20 • Suisse
Internet iso@iso.ch
Imprimé en Suisse
---------------------- Page: 2 ----------------------
ISO
ISO 834-1:1999(F)
Avant-propos

L'ISO (Organisation internationale de normalisation) est une fédération mondiale d'organismes nationaux de

normalisation (comités membres de l'ISO). L'élaboration des Normes internationales est en général confiée aux

comités techniques de l'ISO. Chaque comité membre intéressé par une étude a le droit de faire partie du comité

technique créé à cet effet. Les organisations internationales, gouvernementales et non gouvernementales, en

liaison avec l'ISO participent également aux travaux. L'ISO collabore étroitement avec la Commission

électrotechnique internationale (CEI) en ce qui concerne la normalisation électrotechnique.

Les projets de Normes internationales adoptés par les comités techniques sont soumis aux comités membres pour

vote. Leur publication comme Normes internationales requiert l'approbation de 75 % au moins des comités

membres votants.

La présente partie de l’ISO 834 a été élaborée par le comité technique ISO/TC 92, Sécurité au feu, sous-comité

SC 2, Résistance au feu.

L’ISO 834-1 annule et remplace la première édition (ISO 834:1975 ainsi que l'ISO 834/Amd 1:1979 et

l'ISO 834/Amd 2:1980) dont elle constitue une révision technique. Cette révision a été faite afin d'augmenter la

précision et la reproductibilité de la méthode d'essai. Ces dispositions sont complétées par les commentaires

contenus dans l’ISO 834-3.

L’ISO 834 comprend les parties suivantes présentées sous le titre général Essais de résistance au feu — Éléments

de construction:
Partie 1: Exigences générales

— Partie 2: Exigences particulières à différents éléments porteurs et non porteurs

— Partie 3: Commentaires sur les méthodes d’essais et application des données d’essais

— Partie 4: Exigences spécifiques relatives aux éléments porteurs verticaux de séparation

— Partie 5: Exigences spécifiques relatives aux éléments porteurs horizontaux de séparation

— Partie 6: Exigences spécifiques relatives aux poutres
— Partie 7: Exigences spécifiques relatives aux poteaux

— Partie 8: Exigences spécifiques relatives aux éléments porteurs verticaux de séparation

— Partie 9: Exigences spécifiques relatives aux éléments porteurs horizontaux de séparation

— Partie 10: Méthode de fixation de la contribution des matériaux de protection appliqués aux éléments de

structures métalliques

— Partie 11: Méthode d'évaluation de la contribution des matériaux de protection appliqués aux éléments de

structures métalliques
iii
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ISO
ISO 834-1:1999(F)
Introduction

Les modifications significatives apportées par rapport à l'ISO 834:1975 sont les exigences concernant:

 la précision de l'équipement de mesure;

 les tolérances qui s'appliquent aux écarts de la courbe des températures moyennes du four par rapport à la

courbe de chauffage normalisée;
 les conditions de surpression des éléments verticaux et horizontaux;
 spécification de la charge d'essai;
 le conditionnement;
 l'utilisation de l'instrumentation;
 les critères concernant la capacité de charge.

D'une façon générale, cette révision rend compte de l'objectif du groupe de travail de fournir une Norme

internationale disposée selon un ordre logique et donnant une précision plus grande dans le développement et

l'application des résultats obtenus en utilisant le même équipement ou des équipements différents (il est prévu

d'augmenter l'aspect répétabilité en développant, dans un futur proche, un sous-programme d'étalonnage de

précision qui traitera des paramètres tels que l'uniformité de température, les gradients de pression, la

concentration en oxygène, les matériaux de revêtement du four, etc.).
---------------------- Page: 4 ----------------------
NORME INTERNATIONALE ISO ISO 834-1:1999(F)
Essai de résistance au feu — Éléments de construction —
Partie 1:
Exigences générales
1 Domaine d’application

La présente partie de l’ISO 834 décrit une méthode d'essai en vue de déterminer la résistance au feu de divers

éléments de construction quand ils sont soumis à des conditions normalisées d'exposition au feu. Les données de

l'essai ainsi obtenues permettront d'établir ensuite une classification en fonction de la durée pendant laquelle la

performance des éléments soumis à l'essai dans ces conditions satisfait aux critères spécifiés.

2 Références normatives

Les normes suivantes contiennent des dispositions qui, par suite de la référence qui y est faite, constituent des

dispositions valables pour la présente partie de l’ISO 834. Au moment de la publication, les éditions indiquées

étaient en vigueur. Toute norme est sujette à révision et les parties prenantes des accords fondés sur la présente

partie de l’ISO 834 sont invitées à rechercher la possibilité d'appliquer les éditions les plus récentes des normes

indiquées ci-après. Les membres de la CEI et de l'ISO possèdent le registre des Normes internationales en vigueur

à un moment donné.
ISO 13943:— , Sécurité au feu — Vocabulaire.
CEI 60584-1:1995, Couples thermoélectriques — Partie 1: Tables de référence.
3 Définitions

Pour les besoins de la présente partie de l’ISO 834, les définitions données dans l’ISO 13943 ainsi que les

définitions suivantes s'appliquent.

3.1 propriétés réelles du matériau: Propriétés d'un matériau déterminées à partir d'échantillons représentatifs

prélevés dans l'éprouvette pour l'essai au feu selon les exigences de la norme de produit correspondante.

3.2 essai d’étalonnage: Procédure destinée à évaluer de façon expérimentale les conditions d'essai.

3.3 déformation: Tout changement des dimensions ou de la forme d'un élément de construction due à des actions

structurelles ou thermiques. Ceci comprend le fléchissement, la dilatation ou la contraction d'éléments.

3.4 élément de construction: Un élément de construction donné, par exemple un mur, une cloison, un plancher,

un toit, une poutre ou un poteau.
1) À publier.
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3.5 isolation: L'aptitude d'un élément de séparation utilisé sur une construction, lorsqu'il est exposé au feu d'un

côté, à maintenir l'augmentation de température du côté protégé en-deçà des niveaux spécifiés.

3.6 étanchéité: L'aptitude d'un élément de séparation utilisé sur une construction, lorsqu'il est exposé au feu d'un

côté, à éviter que les flammes ou les gaz chauds ne le franchissent ou que des flammes ne se forment sur le côté

non exposé.

3.7 capacité porteuse: L'aptitude d'une éprouvette d'un élément porteur à supporter sa charge d'essai, lorsque

nécessaire, sans dépasser des critères définis pour l'ampleur du fléchissement et la vitesse de déformation.

3.8 élément porteur: Un élément destiné à être utilisé pour supporter une charge extérieure dans une construction

et pour assurer cette fonction en cas d'incendie.

3.9 plan de pression neutre: Niveau auquel la pression est égale à l'intérieur et à l'extérieur du four.

3.10 niveau de plancher théorique: Le niveau de plancher présumé par rapport à la position de l'élément de

construction en service.

3.11 assujettissement: La contrainte à la dilatation ou à la rotation (provoquée par des phénomènes thermiques

et/ou mécaniques) permise par les conditions régnant aux extrémités, aux bords ou sur les supports d'une

éprouvette.

NOTE Parmi divers exemples de types d'assujettissements, signalons les assujettissements longitudinaux, rotationnels et

latéraux.

3.12 élément de construction: Un élément qui est destiné à être utilisé pour maintenir une séparation entre deux

zones contiguës dans une construction en cas d'incendie.

3.13 cadre support: La construction qui peut être nécessaire pour réaliser un essai sur certains éléments de

construction et dans laquelle l'éprouvette est assemblée, par exemple le mur dans lequel est aménagée une porte.

3.14 construction d’essai: L'assemblage complet de l'éprouvette avec sa construction portante.

3.15 éprouvette: Un élément (ou une partie) de construction fourni dans le but de déterminer soit sa résistance au

feu, soit sa contribution à la résistance au feu d'un autre élément de construction.

4 Symboles
Symbole Description Unité
Surface située au-dessous de la courbe moyenne réelle de
A °C ⋅ min
temps/température du four
Surface située au-dessous de la courbe normalisée
A °C ⋅ min
temps/température
Contraction axiale mesurée à partir du début de l'échauffement. mm
C(t) Contraction axiale relevée au temps t de l'essai
dC Taux de contraction axiale, calculé avec l'équation suivante: mm/min
Ct-Ct
() ( )
()-21
d Distance entre la dernière fibre de la zone de compression théorique mm
et la dernière fibre de la zone de traction théorique de la section
structurelle de l'éprouvette en flexion
d Écart en pourcentage (voir 6.1.2) %
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Fléchissement mesuré à partir du début de l'échauffement mm
D(t) Fléchissement relevé au temps t de l’essai
Vitesse de déformation, calculée avec l'équation suivante : mm/min
Dt-D t
() ( )
()-21
h Hauteur initiale d'une éprouvette à chargement axial mm
L Longueur de la portée libre de l'éprouvette mm
t Durée écoulée depuis le début de l'échauffement min
T Température à l'intérieur du four d'essai °C
5 Matériel d'essai
5.1 Généralités

Le matériel utilisé pour réaliser les essais comprend essentiellement les équipements suivants:

a) four spécialement conçu pour soumettre l'éprouvette aux conditions d'essai indiquées dans l'article approprié;

b) matériel de régulation pour maintenir la température des fours conforme aux exigences de 6.1;

c) équipement de régulation et de surveillance de la pression des gaz à l'intérieur du four pour la maintenir

conforme aux exigences de 6.2;

d) cadre dans lequel l'éprouvette peut être assemblée au four pour permettre de réaliser les conditions de

chauffage, de pression et d'appui appropriées;

e) moyens de chargement et d'assujettissement de l'éprouvette, y compris la régulation et la surveillance des

charges;

f) appareillage de mesure de la température dans le four et sur la face non exposée de l'éprouvettes, et aux

endroits de l'éprouvette où cela s'avère nécessaire;

g) appareillage de mesure des déformations de l'éprouvette aux endroits spécifiés dans les articles appropriés;

h) appareillage servant à évaluer l'étanchéité de l'éprouvette, à déterminer la conformité aux critères de

performance décrits dans l’article 10 et à mesurer le temps écoulé.
5.2 Fours

Les fours d'essais seront conçus pour utiliser des combustibles liquides ou gazeux et seront en mesure d'assurer les

tâches suivantes:

a) chauffage des éléments de séparation verticaux ou horizontaux sur une face; ou

b) chauffage des poteaux sur tous les côtés; ou
c) chauffage des parois sur plus d'un côté; ou
d) chauffage des poutres sur trois ou quatre côtés, selon le cas.

NOTE Les fours peuvent être conçus pour que les ensembles comportant plus d'un élément puissent être éprouvés en

même temps, pourvu que toutes les conditions requises pour chacun des éléments soient respectées.

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Le revêtement des fours sera composé de matériaux ayant une densité inférieure à 1 000 kg/m . Ces matériaux de

revêtement auront une épaisseur d'au moins 50 mm et composera au moins 70 % de la surface interne exposée du

four.
5.3 Équipement de mise en charge

L'équipement de mise en charge doit permettre de soumettre les éprouvettes au niveau de chargement déterminé

selon 6.4. La charge peut être appliquée hydrauliquement, mécaniquement ou à l'aide de poids.

L'équipement de mise en charge sera également capable de simuler des conditions de chargement uniforme, de

chargement ponctuel, de chargement axial ou de chargement excentré, selon le cas qui convient pour l'éprouvette .

L'équipement de mise en charge sera également capable de maintenir le niveau de la charge d'essai à une valeur

constante (à moins de ± 5% de la valeur exigée) sans modifier sa distribution , et pendant toute la durée de la période

de mise en charge. L'équipement doit être capable de suivre la déformation maximale et le taux de déformation de

l'éprouvette pendant toute la durée du test.

L'équipement de mise en charge ne doit pas influencer de façon significative le transfert de chaleur au travers de

l'éprouvette et ni empêcher l'utilisation de feutres isolants du thermocouple. Il ne doit pas perturber la mesure de la

température de surface et/ou de la déformation et permettra une observation générale de la surface non exposée. La

surface totale des points de contact situés entre l'équipement de mise en charge et la surface de l'éprouvette ne doit

pas dépasser 10% de la surface d'une éprouvette horizontale.

Lorsque la charge doit être maintenue après la période de chauffage, l'équipement doit être prévu en conséquence.

5.4 Cadre d’assujetissement et de support

On utilisera des cadres spéciaux ou tout autre moyen pour reproduire les conditions limites et d'appui des éprouvettes

conformément à 6.5.
5.5 Appareillage
5.5.1 Température
5.5.1.1 Thermocouples de four

Les thermocouples de four doivent être des pyromètres plats comprenant l'assemblage suivant: une tôle d'acier pliée,

sur laquelle est fixé le thermocouple, et qui contient un matériau isolant. L'équipement de mesure et d'enregistrement

doit pouvoir fonctionner dans les limites spécifiées en 5.6.

L'élément doit être construit à partir de plaques en alliage de nickel de (150 ± 1) mm de long sur (100 ± 1) mm de large

et sur (0,7 ± 0,1) mm d'épaisseur, pliées de façon à obtenir la construction illustrée à la figure 1.

La jonction de mesure doit se composer de fils en nickel-chrome/nickel-aluminium (type K) tel que défini dans la norme

CEI 60584-1, placés dans une gaine en alliage d'acier résistant à la chaleur, de 1 mm de diamètre nominal, et

renfermant un isolant minéral, la soudure chaude étant isolée électriquement de la gaine. La soudure chaude du

thermocouple doit être fixée sur le pyromètre plat, en son centre géométrique, dans la position illustrée sur la figure 1,

à l'aide d'une petite bande d'acier constituée du même matériau que le pyromètre plat. La bande d'acier peut être

soudée sur le pyromètre ou vissée pour faciliter le remplacement du thermocouple. Les dimensions de la bande

doivent être approximativement de 18 mm sur 6 mm si elle est soudée par points sur la plaque ou de 25 mm sur 6 mm

en valeur nominale si elle est vissée sur la plaque. La vis doit faire 2 mm de diamètre.

L'assemblage de la plaque et du thermocouple doit être équipé d'un matériau isolant inorganique de

(97 ± 1) mm ´ (97 ± 1) mm ´ (10 ± 1) mm d'épaisseur en valeur nominale et d'une masse volumique de

(280 ± 30) kg/m .

Avant sa première utilisation, tout pyromètre plat doit être «vieilli» en séjournant pendant 1 h dans une étuve

préchauffée à 1 000 °C.
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NOTE Si les pyromètres sont exposés pendant 90 min dans un four d'essai de résistance au feu selon la courbe

normalisée température/temps, cette méthode est considérée comme acceptable, au lieu d'utiliser une étuve.

Lorsque le pyromètre plat est utilisé plusieurs fois, il faut tenir à jour un rapport concernant son utilisation, où seront

indiquées, pour chaque utilisation, les vérifications effectuées et la durée d'utilisation. Le thermocouple et le matériau

isolant doivent être remplacés après 50 h d'exposition dans le four.
Dimensions en millimètres
Légende
1 Thermocouple chemisé avec soudure chaude isolée
2 Bande d'acier soudée par points ou vissée
3 Soudure chaude du thermocouple
4 Matériau isolant
5 Plaque d'alliage de nickel de (0,7 ± 0,1) mm d'épaisseur
6 Face «A»
Figure 1 — Illustration d'un pyromètre plat
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Dimensions en millimètres
Légende
1 Fil de 0,5 mm de diamètre
2 Disque de cuivre de 0,2 mm
a) Jonction de mesure d'un disque de cuivre
Légende
1 Fil de 0,5 mm de diamètre
2 Location de l'entaille alternative
b) Disque de cuivre et feutre isolant
Figure 2 — Thermocouple de surface non exposée avec matériau isolant
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5.5.1.2 Thermocouples de surface non exposée

La température de la surface non exposée de l'éprouvette doit être mesurée à l'aide de thermocouples à disque du

type illustré à la Figure 2. Afin d'assurer un bon contact thermique, les fils des thermocouples de 0,5 mm de diamètre

doivent être soudés ou brasés à un disque de cuivre de 0,2 mm d'épaisseur sur 12 mm de diamètre. Chaque

thermocouple doit être recouvert d'un carré de feutre isolant inorganique de 30 mm ´ 30 mm ´ (2,0 ± 0,5) mm

d'épaisseur, sauf spécification contraire dans les normes pour éléments spécifiques. Le matériau du carré de feutre

3 3

doit avoir une densité de 900 kg/m ± 100 kg/m . L'équipement de mesure et d'enregistrement doit pouvoir fonctionner

dans les limites spécifiées en 5.6.

Le feutre isolant doit être collé à la surface de l'éprouvette, sans aucun adhésif entre le disque de cuivre et la surface

de l'éprouvette ou entre le disque de cuivre et l'isolant.
5.5.1.3 Thermocouples mobiles

Un ou plusieurs thermocouples mobiles du type illustré à la figure 3 ou autres appareils de mesure de la température

dont la précision et le temps de réponse sont manifestement inférieurs ou égaux au minimum au type illustré à la figure

3 doivent être disponibles pour mesurer, pendant l’essai, la température de la surface non exposée à des endroits où

l’on présent des températures élevées. La jonction de mesure des thermocouples se compose de fils de

thermocouples de 1,0 mm de diamètre soudés ou brasés à un disque de cuivre de 12 mm de diamètre et 0,5 mm

d’épaisseur. Ces thermocouples doivent comporter une poignée permettant de les appliquer sur n’importe quel point

de la surface non exposée de l’éprouvette.
Dimensions en millimètres
Légende
1 Support en acier résistant à la chaleur de 13 mm de diamètre
2 Isolateur en céramique à double alésage de 8 mm de diamètre
3 Fils de thermocouple de 1,0 mm de diamètre
4 Disque de cuivre de 12 mm de diamètre et 0,5 mm d'épaisseur
Figure 3 — Thermocouple mobile
5.5.1.4 Thermocouples internes

Lorsqu'on a besoin de renseignements sur la température à l'intérieur d'une éprouvette ou d'un composant particulier,

ces informations seront obtenues au moyen de thermocouples présentant des caractéristiques appropriées à la

gamme de températures à mesurer, et adaptées au type de matériau contenu dans l'éprouvette.

5.5.1.5 Thermocouples de température ambiante

Un thermocouple doit être employé pour indiquer la température ambiante dans le laboratoire à proximité de

l'éprouvette aussi bien avant que pendant la durée de l'épreuve. Le thermocouple doit avoir un diamètre nominal de

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3 mm, une isolation en matériau minéral et une enveloppe en acier inoxydable, de type K, comme défini dans la

CEI 60584-1. La soudure chaude sera protégée des chaleurs rayonnantes et des courants d'air.

5.5.2 Pression

La pression dans le four doit être mesurée par l'un des modèles de capteurs illustrés à la figure 4. L'équipement de

mesure et d'enregistrement devra pouvoir fonctionner dans les limites spécifiées en 5.6.

Dimensions en millimètres
Légende
1 Vers le transducteur de pression
2 Ouvert
3 Tube en acier inoxydable (diamètre intérieur 5 mm à 10 mm)
a) Type 1: Capteur en "T"
Légende
1 Trous de 3,0 mm de diamètre

2 Trous de 3,0 mm de diamètre disposés tout autour de la tige à intervalles de 40°

3 Extrémité soudée
4 Tube en acier inoxydable
b) Type 2: Capteur tubulaire
Figure 4 — Capteurs de pression
5.5.3 Charge

Lorsqu'on utilise des poids, il n'est pas nécessaire d'effectuer d'autres mesures de la charge. Les charges appliquées

par des systèmes hydrauliques seront mesurées au moyen d'un extensomètre ou d'un autre équipement approprié

offrant la même précision ou en surveillant la pression hydraulique à un endroit approprié. L'équipement de mesure et

d'enregistrement devra pouvoir fonctionner dans les limites spécifiées en 5.6.
5.5.4 Déformation

Les mesures de déformation peuvent être effectuées en utilisant un équipement basé sur des techniques mécaniques,

optiques ou électriques. Dans le cas où cet équipement est utilisé pour vérifier la conformité aux critères de

performance (par exemple pour des mesures de fléchissement ou de contraction), il devra pouvoir fonctionner à une

fréquence d'au moins une lecture par minute. Toutes précautions nécessaires doivent être prises pour éviter toute

dérive des relevés du capteur dues à la chaleur.
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5.5.5 Étanchéité
5.5.5.1 Tampon de coton

Sauf spécification contraire dans les normes relatives aux éléments spécifiques, le tampon de coton utilisé dans la

mesure de l'étanchéité doit se composer de fibres de coton neuves, non teintes et douces. Il doit mesurer 100 mm de

côté par 20 mm d'épaisseur et peser entre 3 g et 4 g. Il doit être conditionné avant l'emploi par séchage dans une

étuve à 100 °C ± 5 °C pendant au moins 30 min. Après séchage, il peut être placé dans un dessiccateur ou dans un

récipient à l'épreuve de l'humidité jusqu'à l'emploi. Pour son utilisation, il doit être monté dans un support métallique,

comme illustré à la figure 5, comportant une poignée.
Dimensions en millimètres
Légende
1 Articulation
2 Poignée de longueur adaptée
3 Fil d'acier de support de 0,5 mm de diamètre
4 Couvercle articulé avec verrou
5 Cadre en fil d'acier de 1,5 mm de diamètre
Figure 5 — Support du tampon de coton
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5.5.5.2 Calibres d'ouverture

Deux modèles de calibres d'ouverture, tel qu'illustré à la figure 6, seront disponibles pour effectuer les mesures

d'étanchéité. Ils seront réalisés à l'aide de tiges d'acier inoxydable cylindriques d'un diamètre de 6 mm ± 0,1 mm et de

25 mm ± 0,2 mm. Ils doivent être dotés de poignées isolées de longueur adaptée.
Dimensions en millimètres
Légende
1 Tige en acier inoxydable
2 Poignée isolée
Figure 6 — Calibres d'ouverture
5.6 Précision des instruments de mesure

Pour la réalisation des essais de résistance au feu, les instruments de mesure devront répondre aux conditions de

précision suivantes:
a) mesure de la température: four ± 15 °C
surface non exposée ambiante ± 4 °C
autres ± 10 °C
b) mesure de la pression: ± 2 Pa
c) niveau de charge: ± 2,5 % de la charge d'essai
d) mesure de contraction ou de dilatation axiale: ± 0,5 mm
e) autres mesures de déformation: ± 2 mm
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6 Conditions d'essai
6.1 Température du four
6.1.1 Courbe de chauffage

La température moyenne du four mesurée par les thermocouples spécifiés en 5.5.1.1 doit être surveillée et contrôlée

afin qu'elle suive l'équation (voir figure 7):
T = 345 lg (8t + 1) + 20
T est la température moyenne du four, en degrés Celsius ;
t est le temps, en minutes.
Légende
1 Courbe température du four/temps
Figure 7 — Courbe normalisée température/temps
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6.1.2 Tolérances

L'écart en pourcentage d de l'intégrale de la courbe de température moyenne enregistrée par les thermocouples de

four spécifiés en fonction du temps par rapport à l'intégrale de la courbe d'échauffement temps/température normalisée

doit être inférieur ou égal à :
a) d < 15 % pour 5 , t < 10
b) d = 15 2 0,5 (t -10) % pour 10 , t < 30
c) d = 5 - 0,083 (t -30) % pour 30 , t < 60
d) d = 2,5 % pour t . 60
d est l'écart, en pourcentage;
AA-s
d =

A est la surface sous la courbe réelle de température moyenne du temps passé au fouren fonction du

temps ;
est la surface sous la courbe normalisée de température en fonction du temps;
t est le temps, en minutes.

Toutes les surfaces doivent être calculées suivant la même méthode, c'est-à-dire en faisant la somme des surfaces à

des intervalles d'au plus 1 min pour a), et 5 min pour b), c) et d) et doit être calculée à partir du temps zéro. Le début de

l'essai est décrit en 9.3.

À n'importe quel moment après les 10 premières minutes de l'essai, la température enregistrée par n'importe quel

thermocouple dans le four ne s'écartera pas de plus de 100°C de la température correspondante de la courbe

normalisée de température en fonction du temps.

Dans le cas d'éprouvettes contenant une quantité importante de matériaux combustibles, l'écart pourra être dépassé

pendant une période n'excédant pas 10 min pour autant que cet écart soit clairement identifié comme étant associé à

l'inflammation soudaine de quantités importantes de matériaux combustibles augmentant la température moyenne du

four.
6.2 Différentiel de pression du four
6.2.1 Généralités

Un gradient de pression linéaire existe sur la hauteur du four et bien que le gradient varie légèrement en fonction de la

température du four, on peut supposer une valeur moyenne de 8 Pa par mètre de hauteur lors de l'évaluation des

conditions de pression dans le four. La position de l'axe de pression neutre peut être ajustée en contrôlant

l'alimentation d'air ou la surface et l'emplacement des ouvertures du four aux niveaux supérieur et inférieur.

La valeur de la pression du four à une hauteur spécifiée sera la valeur moyenne nominale, sans tenir compte des

fluctuations rapides de pression qui sont associées à la turbulence, etc., et sera déterminée par rapport à la pression à

l'extérieur du four à la même hauteur. La valeur moyenne de la pression de contrôle du four sera surveillée suivant

9.4.2. Elle sera vérifiée à 5 Pa d'écart dans les 5 min qui suivent le début de l'essai, et sera verifée à 3 Pa d'écart

dans les 10 min qui suivent le début de l'essai.
6.2.2 Éléments verticaux

Le four doit fonctionner de telle façon qu'une pression nulle puisse être obtenue à une hauteur de 500 mm au-dessus

du niveau du plancher théorique de l'éprouvette. Cependant, la pression au sommet de l'éprouvette ne sera pas

supérieure à 20 Pa et la hauteur du plan de pression neutre sera ajustée en conséquence.

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6.2.3 Éléments horizontaux

Le four doit fonctionner de telle façon qu'une pression de 20 Pa puisse être mesurée à un point situé à 100 mm en

dessous de la sous-face de l'éprouvette d'essai ou du niveau du plafond théorique pour l'essai des poutres.

6.3 Mise en charge

Le laboratoire d'essai doit indiquer clairement sur quelle base la charge a été déterminée. La charge d'essai peut être

déterminée sur l'une des bases suivantes:
a) les propriétés effectives du matériau
...

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