Foreword

TCVN 9311-1:2012 is completely equivalent to ISO 834-1:1999.

TCVN 9311-1:2012 was converted from TCXDVN 342:2005 (ISO 834-1:1999) according to the provisions of Clause 1, Article 69 of the Law on Standards and Technical Regulations and Point b), Clause 1, Article 7 of the Government’s Decree No. 127/2007/ND-CP dated August 1, 2007 detailing the implementation of some articles of the Law on Standards and Technical Regulations.

The set of TCVN 9311 under the general title “Fire-resistance tests – Elements of building construction” consists of the following parts:

• TCVN 9311-1:2012, Part 1: General requirements.
• TCVN 9311-3:2012, Part 3: Guidance on test methods and application of test data.
• TCVN 9311-4:2012, Part 4: Specific requirements for loadbearing vertical separating elements.
• TCVN 9311-5:2012, Part 5: Specific requirements for loadbearing horizontal separating elements.
• TCVN 9311-6:2012, Part 6: Specific requirements for beams.
• TCVN 9311-7:2012, Part 7: Specific requirements for columns.
• TCVN 9311-8:2012, Part 8: Specific requirements for non-loadbearing vertical separating elements.

The set of ISO 834 “Fire-resistance tests – Elements of building construction” also includes the following parts:

• ISO 834-9:2003, Fire-resistance tests – Elements of building construction – Part 9: Specific requirements for non-loadbearing ceiling elements
• ISO/DIS 834-10, Fire resistance tests – Elements of building construction – Part 10: Specific requirements to determine the contribution of applied fire protection materials to structural elements
• ISO/DIS 834-11, Fire resistance tests – Elements of building construction – Part 11: Specific requirements for the assessment of fire protection to structural steel elements

TCVN 9311-1:2012 was prepared by the Institute of Architecture, Urban and Rural Planning, proposed by the Ministry of Construction, appraised by the Directorate for Standards, Metrology and Quality, and announced by the Ministry of Science and Technology.

1. Scope

This standard specifies the test method for determining the fire resistance of building elements, under standard fire exposure conditions. The data obtained allows for classifying the performance of components based on the period for which they satisfy specified criteria when tested as specified.

2. Normative references

The following normative documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 13943, Fire safety – Vocabulary.

IEC 60584-1:1995, Thermocouples – Part 1: Reference tables.

3. Terms and definitions

For the purposes of this standard, the terms and definitions given in ISO 13943 and the following apply.

3.1 actual material properties

properties of a material as determined on samples taken from representative specimens that have been tested in accordance with the appropriate product standard

3.2 calibration test

procedure for evaluating test conditions by practical demonstration

3.3 deformation

any change in dimension or shape of a building element caused by structural and/or thermal actions
Deformation includes sagging, expansion or contraction of the element.

3.4 elements of building construction

components of a building structure 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

3.6 integrity

ability of a separating element of building construction, when exposed to fire on one side, to prevent the passage of flames and hot gases and to prevent the occurrence of flames on the unexposed side

3.7 load-bearing capacity

ability of a test specimen to support its test load, where appropriate, without exceeding specified criteria in terms of either the extent or rate of deformation

3.8 load-bearing element

element used to support an external load in a building and which is required to resist load in a fire situation

3.9 neutral pressure plane

elevation at which the internal and external pressures of the furnace are equal

3.10 nominal floor datum

nominal floor level corresponding to the position of use of a building element

3.11 restraint

limitation of the expansion, rotation or other forms of displacement (generated by thermal and/or mechanical actions) at the edges, ends or supports of a test specimen

NOTE Examples of different types of restraints include longitudinal, transverse and rotational restraint.

3.12 separating element

element used to separate two adjacent areas in a building in the event of fire

3.13 supporting construction

construction that may be required to be constructed for the testing of certain elements of building construction into which the specimen will be assembled, for example a wall with a doorset

3.14 test construction

complete assembly comprising the test specimen and the supporting construction

3.15 test specimen

element (or part of an element) of building construction used to determine its fire resistance or used to determine its contribution to the fire resistance of another element of building construction

4. Symbols

Symbol	Description	Unit
A	Area under the actual average furnace temperature/time curve of the testing furnace	°C. min
As	Area under the standard temperature/time curve	°C. min
C	Axially recorded contraction at the commencement of heating	mm
C(t)	Axially recorded contraction at time t of the test	mm
	The rate of axial contraction:	mm/min
d	Distance from design compression fibre to design tensile fibre of the structural section of a flexural test specimen	mm
D	Deflection recorded at the commencement of heating	mm
D(t)	Recorded deflection at time t of the test	mm
	The rate of deflection:	mm/min
h	Initial height of axially loaded test specimen	mm
L	Clear span of test specimen	mm
de	Percentage deviation (see 6.1.2)	%
t	Time from the commencement of heating	min
T	Furnace temperature	oC

5. Test equipment

5.1 General

The equipment used to carry out the tests consists essentially of the following:

a) a furnace specially designed to enable the test specimen to be subjected to the test conditions specified in the appropriate clauses;

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

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

d) a frame, which may be mounted with the furnace, in which the test specimen can be erected to ensure the appropriate hot gas pressure and support conditions;

e) equipment for applying load and/or restraint to the test specimen, including control and measurement of the load;

f) equipment for measuring the temperature within the furnace and on the unexposed surfaces and, where required within the test construction;

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

h) equipment for assessing the integrity of the test specimen, its compliance with the performance criteria described in Clause 10, and its time of failure.

5.2 Furnace

The furnace shall be designed to employ liquid or gaseous fuel and shall be capable of:

a) heating a vertical or horizontal separating element from one side only;

b) heating a column on all sides;

c) heating a wall from more than one side;

d) heating a beam from three or four sides, as required.

NOTE Furnaces may be designed such that combinations of two or more elements may be tested simultaneously, provided that the requirements for each specific element are fully satisfied.

The lining of the furnace shall be made from materials with a density of less than 1000 kg/m³. The lining shall have a thickness of at least 50 mm and shall constitute at least 70 % of the exposed surface area of the furnace lining.

5.3 Loading equipment

The loading equipment shall be capable of subjecting the test specimens to the levels of load specified in 6.3. The loading may be applied hydraulically, mechanically or by the use of weights.

The loading equipment shall be capable of simulating conditions of uniform, concentrated, axial or eccentric loading appropriate to the test construction. It shall also be capable of maintaining the test load (within ± 5 % of the required value) at a constant value without changing the load distribution throughout the period of load application. It shall respond sensitively to the maximum deformation and rate of deformation of the test specimen during the test.

The loading equipment shall not significantly influence heat transfer through the specimen or impair the use of packing pieces for the thermocouples. It shall not affect the surface and/or deformation measurements and shall permit overall unobstructed view of the unexposed face. The total area of contact between the loading equipment and the surface of the test specimen shall not exceed 10 % of the exposed surface area of a horizontal test specimen.

Provision shall be made, if necessary, to maintain the load beyond the time at which heating is discontinued.

5.4 Frames for restraining and supporting

Frames and other specialized rigs shall be used as necessary to reproduce support and boundary conditions appropriate to the test specimens as specified in 6.4.

5.5 Instrumentation

5.5.1 Temperature

5.5.1.1 Furnace thermocouples

Furnace thermocouples shall be plate thermometers, comprised of an assembly of a folded steel plate, thermocouple fixed to it and containing insulation material. The measuring and recording equipment shall have a response time and a sensitivity which will enable operation within the limits specified in 5.6.

The plate shall be made from nickel alloy sheet (150 ± 1) mm long, (100 ± 1) mm wide and (0.7 ± 0.1) mm thick, folded as shown in Figure 1.

The thermocouple shall be 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. This 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 x 6 mm if it is spot-welded to the plate and nominally 25 mm x 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 into a pad of inorganic insulation material nominally (97 ± 1) mm by (97 ± 1) mm by (10 ± 1) mm thick with a density of (280 ± 30) kg/m³.

Before the plate thermometer is first used, the complete plate thermometer assembly shall be aged by immersing it in a pre-furnace set at 1 000 °C for 1 h.

NOTE As an alternative to the use of a pre-furnace, the plate face can be exposed to the standard time/temperature curve in the fire resistance furnace for a duration of 90 min.

When the plate thermometer is used more than once, a record shall be kept for each use to facilitate inspection procedures and limit the service life. The thermocouple and insulation pad shall be replaced after 50 h exposure in the fire resistance furnace.

KEY:

1 mineral-insulated thermocouple with insulated hot junction

2 spot-welded or screwed strip

3 hot junction of thermocouple

4 insulation material

5 (0.7 ± 0.1) mm thick nickel alloy plate

6 face A

Figure 1 — Illustration of a plate thermometer

5.5.1.2 Unexposed face thermocouples

The surface temperature of the unexposed face of the test specimen shall be measured by means of thermocouples as shown in Figure 2. To provide good thermal contact, the thermocouple wire, 0.5 mm in diameter, shall be soldered to a 0.2 mm thick, 12 mm diameter copper disk. Each thermocouple shall be covered with a 30 mm square x 2.0 mm ± 0.5 mm thick (nominally) inorganic insulating pad, except where special provisions apply to particular elements. The pad shall have a density of (900 ± 100) kg/m³. The measuring and recording equipment shall have a response time and sensitivity which will enable operation within the limits specified in 5.6.

The insulating pad shall be attached to the surface of the test specimen without bonding the copper disk to the surface or bonding the copper disk to the insulating pad.

Dimensions in millimetres

KEY: 1. 0.5 mm diameter thermocouple wires 2. 0.2 mm thick copper disk
	a) Thermocouple copper disk

KEY: 1. Slots allow insertion of insulation pad over copper disk 2. Alternative slot positions
	b) Copper disk and insulating pad

Figure 2 — Thermocouple and insulating pad for unexposed face

5.5.1.3 Roving thermocouple

In order to measure temperatures on the unexposed face during the test in locations considered likely to be of higher temperature, one or more roving thermocouples shall be available of the design shown in Figure 3, or equivalent measuring device of equal responsiveness. The thermocouple consists of thermocouple wires of 1.0 mm diameter welded to a 0.5 mm thick, 12 mm diameter copper disk. This assembly shall be provided with a handle so that it can be applied to any point on the unexposed face of the test specimen.

KEY:

1. 13 mm diameter stainless steel support tube

2. 8 mm diameter two-hole ceramic insulation tube

3. 1.0 mm diameter thermocouple wires

4. 12 mm diameter, 0.5 mm thick copper disk

Figure 3 — Roving thermocouple assembly

5.5.1.4 Internal thermocouples

Where it is desired to measure temperatures within the test specimen or within a particular component, thermocouples having characteristics appropriate to the range of temperatures to be measured and the nature of the material of the test specimen shall be used.

5.5.1.5 Ambient-temperature thermocouple

A thermocouple shall be used to indicate the ambient temperature in the vicinity of the test specimen within the laboratory just prior to and during the test period. The thermocouple shall be nominally 3 mm in diameter, mineral-insulated, type K as defined in IEC 60584-1, stainless steel sheathed. It shall be protected from radiant heat and draughts.

5.5.2 Pressure

The furnace pressure shall be measured using one of the pressure-sensing devices shown in Figure 4. The measuring and recording equipment shall have a response time and sensitivity which will enable operation within the limits specified in 5.6.

Dimensions in millimetres

KEY: 1. To pressure transducer 2. Gap open 3. Stainless steel tube (5 mm to 10 mm internal diameter)
	a) Type 1: “T” sensor

KEY: 1. 3.0 mm diameter holes 2. 3.0 mm diameter holes 40° apart around tube 3. Welded end 4. Stainless steel tube
	b) Type 2: Pipe sensor

Figure 4 — Pressure-sensing devices

5.5.3 Load

When using weights, no additional measurement of the load during the test is necessary. Loading applied by hydraulic systems shall be measured by means of a load cell or other suitable device of similar accuracy or by monitoring of hydraulic pressure at an appropriate position. The measuring and recording equipment shall have an accuracy within the limits specified in 5.6.

5.5.4 Deformation

Deformation measurements may be made using mechanical, optical or electrical devices. Where they are used to measure performance criteria (e.g. deflection or axial contraction), they shall be capable of providing readings at least every minute. Every precaution shall be taken to prevent spurious deflection of indicators due to heating.

5.5.5 Integrity

5.5.5.1 Cotton pad

The cotton pad used in the measurement of integrity shall be made from new, soft, undyed cotton wool without flame-retardant additives, with a thickness of 20 mm and a size of 100 mm², weighing between 3 g and 4 g, unless otherwise specified in standards relating to specific elements. The cotton pads shall be conditioned before use by drying in an oven at 100 °C ± 5 °C for at least 30 min. They may then be stored in a desiccator until required for use. When used, the cotton pad shall be mounted in a wire cage with a handle, as shown in Figure 5.

KEY: 1. Hinged joint 2. Handle of appropriate length 3. 0.5 mm diameter supporting wire 4. Hinged and clasp lid 5. 1.5 mm diameter wire frame

Figure 5 — Holder for cotton pad

5.5.5.2 Gap gauges

Two types of gap gauges (see Figure 6) are used to measure integrity. They shall be made from stainless steel, having diameters of 6 mm ± 0,1 mm and 25 mm ± 0,2 mm. The standard gap gauge shall have a suitably insulated handle.

KEY:

1. Stainless steel rod

2. Insulated handle

Figure 6 — Gap gauges

5.6 Accuracy of instrumentation

In order to carry out the fire resistance tests, the instrumentation shall be capable of operating within the following limits:

6 Test conditions

6.1 Furnace temperature

6.1.1 Heating curve

The average temperature of the furnace, as derived from the furnace thermocouples specified in 5.5.1.1, shall be monitored and controlled such that it follows the relationship:

T = 345 log₁₀(8t + 1) + 20

where: T is the average furnace temperature, in degrees Celsius;

t is the time, in minutes

KEY:

1. Furnace temperature corresponding to time

Figure 7 — Standard temperature/time curve

6.1.2 Tolerances

The percentage deviation de of the area of the curve of the average temperature recorded by the furnace thermocouples versus time from the area of the standard time/temperature curve shall be within the following limits:

where:

d_e is the percentage deviation;

A is the area under the actual average furnace time/temperature curve;

A_s is the area under the standard time/temperature curve;

t is the time, in minutes.

All areas shall be computed by the same method, that is, by the summation of areas at intervals not exceeding 1 min for a); 5 min for b), c) and d), from zero time. Zero time shall be the commencement of the test as defined in 9.3.

At any time after the first 10 min of test, the temperature recorded by any thermocouple shall not differ from the corresponding temperature of the standard time/temperature curve by more than 100 °C.

For specimens containing significant quantities of combustible materials, the percentage deviation may be exceeded during a period not longer than 10 min provided that it is clearly attributable to ignition and burning of the combustible material by a sudden increase in the average furnace temperature.

6.2 Furnace pressure

6.2.1 General

A linear pressure gradient exists over the height of the furnace and, although changing as the furnace temperature increases, 8 Pa per metre height is assumed to be the nominal reference value for assessing the furnace pressure conditions.

The value of the furnace pressure at a given height shall be the nominal mean value, disregarding rapid fluctuations of pressure caused by turbulence, etc., and shall be established relative to the pressure outside the furnace at the same height. The net mean furnace pressure under control shall be monitored as described in 9.4.2 and held within ± 5 Pa for the first 5 min and ± 3 Pa for the first 10 min from the commencement of the test.

6.2.2 Vertical elements

The furnace shall be operated so that a pressure of zero is established at a height of 500 mm above the nominal floor level. The pressure at the top of the specimen shall not exceed 20 Pa and the level of the neutral pressure plane shall be adjusted accordingly.

6.2.3 Horizontal elements

The furnace shall be operated so that a pressure of 20 Pa is established at a height 100 mm below the underside of the test specimen, or below the nominal roof level in the case of testing beams.

6.3 Loading

The test laboratory shall specify the basis on which the test load is determined. The test load may be defined on the basis of either:

a) the actual properties of the materials of the test specimen and a method of design specified as part of structural design codes;

b) characteristic properties of the materials from which the test specimen is made and a method of design specified as part of structural design codes; supplemented where possible by an indication of the relationship between the loadbearing capacity determined on the basis of actual and characteristic material properties;

c) a utilization load calculated on the basis of a structural code for the element of use, or by the test sponsor for a specific end use application. In this case, an indication of or experimental relationship to the loadbearing capacity determined on the basis of the possible distribution of material properties from which the specimen was taken and the specified characteristic material properties of the specimen shall be given.

6.4 Restraint/boundary conditions

The test construction shall be built into frames and restraining rigs so that the following conditions of support at the ends or edges of the test construction, as appropriate, are simulated and clearly defined as they will apply in the element of use:

The boundary conditions may produce restraint against expansion, contraction or rotation. Alternatively, the boundary conditions may allow free movement. One or more of these boundary conditions (applied to all or some edges) may be chosen for the test specimen. The choice should be based on careful analysis of the in-use conditions.

Elements that in use have uncertain or indeterminate edge or end conditions shall be tested with conditions of support at the edges or ends that ensure as far as possible that the result is conservative.

Where restraint is applied in the test, the restraint condition shall quantify the permitted free movement of the element prior to engagement of the restraint to contraction, expansion or rotation. The external moments and forces imparted to the element by the restraint during the test shall be documented.

6.5 Ambient air conditions

The furnace shall be located within a laboratory of sufficient size to ensure that the air temperature around the separating element does not rise by more than 10 °C above that as the commencement of the test until the test specimen no longer satisfies the insulation criteria. The air in the laboratory shall be allowed to circulate freely. The ambient air temperature shall be between 20 °C ± 10 °C as the commencement of the test and shall be monitored at a distance 1.0 m ± 0.5 m from the unexposed face under conditions such that the sensors are not influenced by radiated heat from the specimen and/or the furnace, particularly in cases where the element is required to satisfy only integrity criteria.

6.6 Deviation from specified test conditions

If furnace temperature, furnace pressure or ambient air temperature conditions are attained during a test that are more severe for the test specimen than those specified, the test shall not be automatically invalid (see Clause 11 on the validity of the test).

6.7 Calibration

Where calibration standards exist, the furnace shall be calibrated according to the requirements of this International Standard for:

– thermal exposure conditions;

– pressure conditions;

– oxygen content.

7 Test specimen

7.1 Construction

The materials, fabrication and construction methods, workmanship, and the method of assembly and erection shall be representative of those intended for use in practice. It is important that the construction is carried out under quality levels normally applied to building construction including appropriate finishes (where relevant). There shall be no variation in constructional details (e.g. use of different jointing systems) within a single test specimen. Any adjustments to facilitate the installation of the specimen into the specific restraint and support frames shall be such that they do not significantly influence specimen behaviour and shall be fully described in the test report.

7.2 Size

The test specimen shall be full size. When a full size test specimen cannot be tested, the size of the specimen shall be as specified in the specific test method for the element.

7.3 Number

At least one specimen shall be tested for each specific condition of support or restraint. For asymmetric separating elements of a construction exposed to fire from either side, representative specimens shall be tested from each direction, unless it can be unambiguously concluded that one direction of exposure will be more onerous. Asymmetric separating elements of a construction required to be exposed to fire from one designated side only shall be tested from that side only.

7.4 Design

The test specimen shall be designed to have, as closely as possible, the strength and moisture content to be expected in normal use. If it contains moisture or is able to absorb it, it shall not be tested until it achieves a moisture condition appropriate to the material. This condition will be regarded as approximating the condition that would be attained in equilibrium 50 % relative humidity and at 23 °C.

One method of achieving this condition is to condition the specimen in an enclosure at a temperature of at least 15 °C and a relative humidity up to a maximum of 75 % for the period necessary to achieve equilibrium moisture content. This is achieved when the results of two successive weighing operations, carried out at an interval of 24 h, do not differ by more than 0,1 % of the mass of the specimen.

Accelerated drying may be used, provided that the process does not alter the properties of component materials nor the distribution of moisture within the specimen, in such a way as to affect its fire resistance. Drying at elevated temperatures shall be below limiting temperatures for the materials.

If, after drying, the required moisture condition cannot be achieved but the designed strength of the absorbent component has been achieved, the fire test may be initiated.

Representative test pieces may be used to determine the moisture content and dried together with the specimen. These shall be manufactured so that they characterize the overall loss of water vapour from the faces as well as from the body of the structural element. The specimen shall be dried to a constant moisture content.

Additional or different rules to achieve equilibrium moisture content may be given in the specific elements standards.

7.5 Verification

The test sponsor shall provide the laboratory with a complete description of the test construction, drawings and parts list, together with the main component manufacturers/suppliers and any installation procedures prior to commencement of the test. All measures taken shall be fully documented before the test begins, to enable the laboratory to verify the conformity of the specimen with the information provided and for any discrepancies to be resolved prior to commencement of the test. To ensure that the description of the element, and particularly the construction, conforms to the element tested, the laboratory shall either supervise the element construction or shall require the delivery of at least one further specimen.

In the event that verification of all aspects of the test construction is not possible at the time of the test, the reliability of post-test evidence will be diminished. Where it is necessary to rely on information from the test sponsor, this shall be noted in the test report. However, the laboratory shall ensure that the components of the specimen are fully documented and accurately described in the test report. Additional procedures for specimen verifications may be found in the test methods for specific products.

8. Installation of instrumentation

8.1. Temperature

8.1.1. Furnace thermocouples (plate thermometers)

The thermocouples used to measure the furnace temperature shall be positioned to give a reliable indication of the average temperature in the vicinity of the test specimen. The number and position of thermocouples for each element type shall be specified in the relevant test method.

The thermocouples shall be positioned so that they are not in contact with flame from the burners of the furnace and are no closer than 17.7 in. to the walls, floor or roof of the furnace.

At the commencement of the test, the thermocouples shall be (3.9 ± 2.0) in. from the fire-exposed face of the test specimen and shall be maintained at this distance, as nearly as possible, during the test period.

The support system shall be such as to ensure that the thermocouples do not fall onto or become affixed to the specimen during the test.

At the commencement of the test, the furnace shall have the number of thermocouples, n, required by the individual test method. If thermocouples are lost and at least n-1 remain in the furnace, the laboratory need not replace the lost thermocouples. If fewer than n-1 thermocouples remain in the furnace, the laboratory shall replace lost thermocouples to ensure that at least n-1 thermocouples remain.

Thermocouples can be damaged by falling debris and lose accuracy if used continuously and become less sensitive with time. Before each test, they shall be checked for continued serviceability. If there are any signs of damage (failure or non-serviceability), they shall not be used but shall be replaced.

Thermocouple mountings shall not be permitted to penetrate or to be fixed onto the test specimen unless they are specially positioned in accordance with additional specifications. Where they penetrate or are fixed onto the test specimen, they shall be arranged to have minimum influence on the specimen’s performance relative to the failure criteria or supplementary information being determined.

8.1.2. Unexposed surface thermocouples

The surface thermocouples as described in 5.5.1.2 shall be attached to the unexposed face to measure the average and maximum temperature rises.

The average temperature rise on the unexposed face shall be based on measurements taken at the center or near the center of the test specimen and at the center or near the center of each of the four quarters of the specimen. For corrugated or ribbed constructions, the number of thermocouples may be increased to ensure correspondence with areas of maximum and minimum thickness. When positioning thermocouples, they shall be at least 2.0 in. clear of any heat-conducting joints, cracks, connections, reinforcement and similar, as well as fasteners such as bolts, screws, etc., and locations where thermocouples could be subject to direct influence of gases traversing the test specimen.

Additional thermocouples shall be provided to measure the maximum temperature rises at locations where higher temperature regimes can be expected. Thermocouples shall not be located on fasteners such as screws or nails that can be expected to be at higher temperatures if the aggregate area of such fasteners is less than 1 % of the area enclosed within a 5.9 in. diameter circle. Thermocouples shall not be attached to fasteners with an exposed surface diameter less than 0.47 in., unless they extend through the assembly. For fasteners smaller than 0.47 in., special measurement devices may be employed. Specific information on the location of the unexposed surface thermocouples is given in the appropriate test method for individual elements.

The thermocouples should preferably be attached to the specimen surface by means of a heat-resistant adhesive with no adhesive between the copper disk and the surface of the specimen or between the copper disk and the pad, and ensuring that any air gap between them is as small as possible. Where adhesive cannot be used, mechanical means of retention such as pins, screws or clips may be used but shall only be in contact with the pad at points not higher than the disk.

8.1.3. Roving thermocouple

The roving thermocouple specified in 5.5.1.3 shall be applied to any suspected hot spots apparent during the test. It is not necessary to hold the thermocouple in place to await steady-state conditions if a temperature of 302°F is not exceeded during a 20 s measuring period. Measurements with the roving thermocouple shall avoid fasteners such as bolts, screws, clips, where temperatures are clearly higher or lower, as specified for the location of supplementary unexposed face thermocouples.

8.1.4. Internal thermocouples

Where internal thermocouples are used as specified in 5.5.1.4, they shall be fixed so as not to influence the performance of the test specimen. The hot junctions shall be attached at the appropriate measuring point by a suitable means including peening into steel sections. The lead wires shall preferably be routed away as soon as possible to prevent the leads becoming hotter than the measuring junction.

NOTE: Where possible, the first 2.0 in. of lead wire nearest the thermocouple should lie in an isothermal plane.

8.2. Pressure sensors

Pressure sensors (see 5.5.2) shall be positioned where they are not subject to direct impingement by convection currents from flames or from hot gas discharge. They are installed to measure and monitor the pressure to provide the conditions specified in 6.2. Both tubes shall be positioned horizontally in the furnace, and as they pass through the furnace wall, the pressure shall be relative to the same reference height from inside to outside the furnace. If “T” sensors are used, the “T” arms shall have a horizontal orientation. Any vertical runs of the tubing to the measuring device shall be maintained at ambient temperature.

8.2.1. Furnaces for vertical elements

The first pressure sensor used to control the furnace pressure shall be positioned within 19.7 in. of the neutral pressure plane.

The second sensor may be used to provide an indication of vertical pressure gradient in the furnace. This sensor shall be positioned within 19.7 in. of the top of the specimen.

8.2.2. Furnaces for horizontal elements

Two pressure sensors shall be in the same horizontal plane but at different locations relative to the perimeter of the specimen. One sensor shall be used for control and one for initial checking.

8.3. Deformation

Instrumentation for measuring the deformation of the test specimen shall be arranged to provide data on the deformation during and after the fire resistance test at appropriate locations.

8.4. Integrity

The measurements of the integrity of the test specimen shall be made by means of cotton pads or gap gauges, as appropriate to the nature and location of the gap (cotton pads may not be suitable for evaluating integrity where substantial gaps develop in regions of negative pressure within the furnace or where gaps are not configured as described in Figure 5), as follows.

8.4.1. Cotton pad

The cotton pad is used by applying the supporting frame, pressed against the surface of the specimen, against a gap or at a location where flaming is observed for a duration of 30 s or until ignition of the cotton pad occurs. Adjustments in position shall be made to maximize the effect of any hot gases.

Where there is either non-planarity of the surface of the specimen or in the area of a gap, care shall be taken to ensure that the legs of the supporting frame maintain the clearance between the pad and any part of the specimen throughout the measurement process.

Laboratory staff may carry out “screening tests” to evaluate the integrity of the specimen. Such screening may lead to the short-term deployment of cotton pads selectively in areas of potential failure and/or moving one pad to and around such areas. Charring of the pad may indicate impending failure of the specimen, but a fresh pad should be used in the manner described to confirm any integrity failure.

For elements or parts of elements that do not satisfy the insulation criteria, the cotton pad shall not be used when the temperature on the unexposed surface (adjacent to the gap) exceeds 572°F.

8.4.2. Gap gauges

The gap gauges are used to assess the size of gaps in the surface of the specimen at time intervals that will be determined by the rate of occurrence and growth of the gaps throughout the test. The two gap gauges shall be applied in turn, without undue force, to determine if:

a) the 0.24 in. gap gauge can be passed through the specimen so that it projects into the furnace, and can be moved a distance of 5.9 in. along the gap;

b) the 0.98 in. gap gauge can be passed through the specimen so that it projects into the furnace.

Any small interruptions to the gauge that do not affect, or only locally affect, the transmission of hot gases through the gap shall be disregarded (for example, small fastening items bridging a joint in the construction that opens due to distortion).

9. Test procedure

9.1. Restraint

Where appropriate, restraint shall be provided by mounting the test specimen within a rigid frame. This method is applicable to walls and certain types of floors (if appropriate). In these cases, any gaps between the edges of the specimen and the frame shall be packed with a stiff material.

The restraint shall be provided by hydraulic or other loading systems. The restraint forces and/or moments shall be generated to resist thermal expansion, contraction or rotation. In such cases, the magnitude of restraint forces and moments is important information and shall be measured at intervals throughout the test.

9.2. Loading

For loadbearing elements, the test load shall be applied at least 15 min before commencing the heating and up to a point where no dynamic effects occur. Any deflections that occur shall be measured. If the specimen contains materials that exhibit marked deformation at the test load, the test load shall be applied and maintained for a suitable period before the fire resistance test commences until the rate of deformation reduces substantially. After loading, and during testing, the load shall be maintained and the loading system shall respond rapidly to specimen deformation to maintain a constant value.

If the specimen is not destroyed and the heating is discontinued, the load shall be removed immediately unless there is a need to monitor the continued loadbearing capacity of the test specimen. In this case, the report shall describe the test specimen cooling phase and whether this was carried out by artificial means by removal from the furnace or by opening the furnace.

9.3. Commencement of test

At 5 min before the commencement of the test, the initial temperature readings of all thermocouples shall be checked to ensure consistency and the datum values shall be recorded. Similar datum values shall be obtained for deformation and the initial condition of the specimen shall be noted.

When the test is commenced, the initial mean internal temperature, if applicable, and the non-fire exposed surface temperature of the test specimen shall be 68°F ± 18°F and within 9°F of the initial ambient temperature (see 6.6).

Prior to the commencement of the test, the furnace temperature shall not exceed 122°F. The commencement of the test is the time at which the heating sequence is initiated to follow the standard heating curve. The failure time shall be measured from this time and all manual or automatic recording and observations shall commence at the same time, and the furnace shall be controlled to conform to the temperature conditions specified in 6.1.

9.4. Measurements and observations

From the commencement of the test, measurements and observations shall be made.

9.4.1. Temperature

The temperatures of the fixed thermocouples (excluding roving thermocouple) shall be measured and recorded at time intervals of not more than 1 min during the heating period.

The roving thermocouple shall be applied as specified in 8.1.3.

9.4.2. Furnace pressure

The furnace pressure(s) shall be continuously measured and recorded, or recorded at intervals not exceeding 5 min, at the control point.

9.4.3. Deformation

Deformations of the test specimen shall be measured and recorded throughout the test. For loadbearing specimens, measurements shall be taken before and after application of the test load and at 1 min intervals during the heating period. Rates of deformation shall be calculated from these measurements.

a) For horizontally loadbearing specimens, measurements shall be taken at a point where maximum deflection is expected to occur (for simply supported elements, normally at mid-span).

b) For loadbearing vertical elements, expansion (denoting an increase in the height of a specimen) shall be recorded as positive and contraction (denoting a decrease in height of a specimen) shall be recorded as negative.

c) For loadbearing vertical elements, the recordings taken shall be used to ascertain the rate of axial contraction or expansion.

9.4.4. Integrity

The cotton pad, gap gauges and observations shall be used to determine:

a) The time at which cracks, gaps or fissures are formed;

b) The time at which sustained flaming occurs on the unexposed surface;

c) The time of ignition of the cotton pad.

The following shall be applied.

a) If a cotton pad is used to evaluate integrity, its position shall be changed after each application but shall be positioned where maximum severity of the draught of hot gases is anticipated.

b) At the place where integrity failure seems most likely to occur, a cotton pad shall be applied every 10 min from the commencement of heating or after a temperature rise of 356°F of the fire unexposed face, whichever is the later.

c) During the final 10 min of the heating period, when integrity failure is imminent, a cotton pad shall be held continuously in the most onerous position until integrity failure occurs.

d) During the last 10 min or 20 % of the anticipated fire resistance period, whichever is the greater, gap gauges shall be applied every 2 min.

9.5. Termination of test

The test shall be regarded as finished when any one of the following events occur:

a) one or more of the performance criteria specified in Clause 10 (as appropriate) is exceeded, or there is a likelihood of damage to equipment;

b) a selected criterion is reached;

c) at the request of the responsible authority.

The test may be continued beyond failure under item b) to obtain additional data.

10. Performance criteria

10.1. General

This describes the performance criteria considered in the appraisal of fire resistance of building elements tested in the standard fire resistance test. Special requirements may be added to the performance criteria or may vary according to the function of the specific element under consideration.

Fire resistance is the time to the nearest minute for which the test specimen continues to maintain its performance in accordance with the criteria. These criteria are established to measure the stability of loadbearing elements and measure the integrity of separating elements. Where a test specimen is representative of a building element that is used to provide both these functions, its performance shall be assessed against both criteria.

10.2. Specific performance criteria

The fire resistance of the test specimen shall be assessed against one or more of the performance criteria given below.

For certain building elements, additional or alternative criteria shall be required.

10.2.1. Loadbearing capacity

This is the time in completed minutes for which the test specimen continues to maintain its ability to support the test load during the test. Supporting the test load shall be deemed to have failed either by excessive deflection or rate of deflection. As relatively rapid deflection may occur until a stabilizing load condition is achieved, the deflection criterion shall only be applied when a deflection of L/30 has been exceeded.

For the purposes of this International Standard, loadbearing capacity shall be considered to have failed when both of the following limits are exceeded.

a) For flexural elements:

where: L is the clear span of the specimen, in millimeters;

d is the distance from the extreme fibre of the design compression zone to the extreme fibre of the design tensile zone of the structural section, in millimeters.

b) For axially loaded elements:

where: h is the initial height, in millimeters.

10.2.2. Integrity

This is the time in completed minutes for which the test specimen continues to maintain its separating function during the test without:

a) causing ignition of a cotton pad (see 8.4.1);

b) permitting the penetration of a gap gauge (see 8.4.2);

c) resulting in sustained flaming on the unexposed surface for a period exceeding 10 s.

10.2.3. Insulation

This is the time in completed minutes for which the test specimen continues to maintain its separating function during the test without developing temperatures on its unexposed surface which:

a) increase the average temperature above the initial average temperature by more than 252°F; or

b) increase at any location (including roving thermocouple) above the initial average temperature by more than 324°F (the initial temperature being the mean unexposed face temperature at the commencement of the test).

11. Test report

A test shall be deemed to be valid if it is conducted within the limits specified on the performance of the test equipment, the test conditions, specimen preparation, installation of instrumentation, test procedure and within the specifications required in this International Standard.

A test shall also be deemed to be valid if the fire exposure conditions relating to furnace temperatures, pressure and ambient temperatures exceed the upper limits of tolerances specified in Clause 6 of this International Standard.

12. Expression of test results

12.1. Fire resistance

The fire resistance of the test specimen shall be expressed as the time in completed minutes for which the appropriate performance criteria were satisfied.

12.2. Performance criteria

12.2.1. Integrity and insulation in relation to loadbearing capacity

The performance criteria of “integrity” and “insulation” shall be deemed to be satisfied if the criteria of “loadbearing capacity” are satisfied.

12.2.2. Insulation in relation to integrity

The performance criteria of “insulation” shall be deemed to be satisfied if the criteria of “integrity” are satisfied.

12.3. Termination of test before failure of construction

When a test is terminated before failure of the construction under the appropriate criteria, the reason for doing so shall be clearly stated in the report. The result shall be expressed in terms of the duration of the test and shall be designated accordingly.

12.4. Expression of results

The following is an example of the method of expressing the test result for a loadbearing separating element in which the “integrity” and “insulation” criteria are exceeded and the test is not continued until full specimen failure at the request of the test sponsor:

Loadbearing capacity: ≥128 min (test discontinued at the request of the test sponsor);

Integrity: 120 min;

Insulation: 110 min.

NOTE: If cotton-pad testing was not carried out due to high temperatures on the unexposed face of the test specimen, this shall be made clear and the point at which this occurred stated.

13. Test report

The test report shall include the following statement:

“The test results relate to the behavior of the test specimens of a product under the particular conditions of the test; they are not intended to be the sole criterion for assessing the potential fire performance of the product in use.”

The test report shall include relevant information on the test specimen and the fire resistance test as specified below (and as required in specific element test standards), including:

a) The name of the testing laboratory and the test standard used, and date of the test;

b) The name of the sponsor and of the manufacturer of the test specimen and any components of the specimen, if known; if not known, a statement to that effect;

c) Details of the method of construction and drawings of the test specimen, together with dimensions of all components and, where applicable, photographs;

d) The relevant properties of the materials used as related to the fire resistance performance of the test specimen, together with the method of determining these properties, including details of the moisture content and conditioning of the test specimen (as appropriate);

e) For loadbearing elements, the load applied to the test specimen and the basis on which the test load was calculated;

f) The support and restraint conditions used and the rationale for their choice;

g) Details of the location of thermocouples, pressure measuring devices and deformation measurement equipment, together with tabular and/or graphical representation of all the data obtained from such equipment during the test;

h) A description of the significant behavior of the test specimen during the test, together with the time of termination of the test based on the criteria (specified in Clause 10);

i) The fire resistance of the test specimen as specified in Clause 12;

j) For asymmetric separating elements, the direction in which the test specimen was tested and the applicability of the result if the construction is required to be exposed to fire from the other side.