SIST EN 993-15:2005
(Main)Methods of test for dense shaped refractory products - Determination of thermal conductivity by the hot-wire (parallel) method
Methods of test for dense shaped refractory products - Determination of thermal conductivity by the hot-wire (parallel) method
This document describes a hot-wire (parallel) method for the determination of thermal conductivity of refractory products and materials. It is applicable to dense and insulating shaped products and to powdered or granular materials (see 6.2), for thermal conductivities of less than 25 W/m.K. The limits are imposed by the thermal diffusivity of the test material and therefore by the dimensions of the test pieces; higher thermal conductivities can be measured if larger pieces are used. Electrically conducting materials cannot be measured.
NOTE 1 The thermal conductivity of products with a hydraulic or chemical bond can be affected by the appreciable amount of water that is retained after hardening or setting and is released on firing. These materials may therefore require pre-treatment; the nature and extent of such pre-treatment and the period for which the test piece is held at the measurement temperature as a preliminary to carrying out the test, are details that are outside the scope of this standard and should be agreed between the parties concerned.
NOTE 2 In general it is difficult to make measurements on anisotropic materials and the use of this method for such materials should also be agreed between the parties concerned.
Prüfverfahren für dichte geformte feuerfeste Erzeugnisse - Teil 15: Bestimmung der Wärmeleitfähigkeit nach dem Heißdraht- (parallel-) Verfahren
Diese Europäische Norm legt ein Heißdraht-Verfahren (Paralleldraht-Verfahren) zur Bestimmung der
Wärmeleitfähigkeit von feuerfesten Erzeugnissen und Werkstoffen fest. Diese Norm gilt für dichte und zur
Wärmedämmung dienende geformte Erzeugnisse sowie pulverförmige oder körnige Werkstoffe (siehe 6.2) mit
einer geringeren Wärmeleitfähigkeit als 25 W/(m · K). Die Grenzen sind durch die Wärmeleitfähigkeit des
Probenwerkstoffes und damit durch die Maße der Probekörper vorgegeben; jedoch können höhere
Wärmeleitfähigkeiten durch Verwendung größerer Probekörper gemessen werden. Elektrisch leitende
Werkstoffe können nicht gemessen werden.
ANMERKUNG 1 Die Wärmeleitfähigkeit von Erzeugnissen mit hydraulischer oder chemischer Bindung kann durch die
nennenswerte Wassermenge, die nach dem Aushärten oder Abbinden zurückbleibt und während des Brennvorganges
abgegeben wird, beeinflusst werden. Diese Werkstoffe können daher eine Vorbehandlung erfordern; die Art und der
Umfang einer derartigen Vorbehandlung sowie die Zeit, für die der Probekörper vor der Durchführung der Prüfung der
Messtemperatur auszusetzen ist, sind Einzelheiten, die außerhalb des Anwendungsbereiches dieser Norm liegen und
sollten zwischen den betreffenden Vertragspartnern vereinbart werden.
ANMERKUNG 2 Messungen an anisotropen Werkstoffen sind im Allgemeinen schwierig durchzuführen, und die Anwen-
dung dieses Verfahrens für derartige Werkstoffe sollte ebenfalls zwischen den betreffenden Vertragspartnern vereinbart
werden.
Méthodes d'essai pour produits réfractaires façonnés denses - Partie 15: Détermination de la conductivité thermique par la méthode du fil chaud (parallele)
La présente Norme européenne spécifie une méthode de détermination de la conductivité thermique des
matériaux et produits réfractaires par la méthode du fil chaud (parallele). Elle s?applique aux produits façonnés
denses et isolants, et aux matériaux en poudre ou en grains (voir 6.2), pour des conductivités thermiques
inférieures a 25 W/m.K. Ces limites sont imposées par la diffusivité thermique du matériau soumis a l?essai et
donc les dimensions des éprouvettes ; des conductivités thermiques plus élevées peuvent etre mesurées si
l?on utilise de plus grandes éprouvettes. Les matériaux électriquement conducteurs ne peuvent pas etre
soumis a cette mesure.
NOTE 1 La conductivité thermique des produits liés (liaison chimique ou hydraulique) peut etre modifiée par la quantité
d?eau notable retenue apres le durcissement ou la prise puis libérée a la cuisson. Ces matériaux peuvent donc nécessiter
un prétraitement ; la nature et l?importance de ce prétraitement, ainsi que la durée de maintien de l?éprouvette a la
température de mesure, étant préliminaires a l?exécution de l?essai proprement dit, sont des détails qui sortent de l?objet
de la norme, et doivent faire l?objet d?un accord entre les parties concernées.
NOTE 2 Il est en général difficile de procéder a des mesures sur des matériaux anisotropes et il convient que
l?application de la présente méthode a ces matériaux fasse également l?objet d?un accord entre les parties concernées.
Metode za preskušanje gostih oblikovanih ognjevzdržnih izdelkov - 15. del: Ugotavljanje toplotne prevodnosti z metodo vroče (vzporedne) žice
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 993-15:2005
01-julij-2005
1DGRPHãþD
SIST EN 993-15:1998
0HWRGH]DSUHVNXãDQMHJRVWLKREOLNRYDQLKRJQMHY]GUåQLKL]GHONRYGHO
8JRWDYOMDQMHWRSORWQHSUHYRGQRVWL]PHWRGRYURþH Y]SRUHGQH åLFH
Methods of test for dense shaped refractory products - Determination of thermal
conductivity by the hot-wire (parallel) method
Prüfverfahren für dichte geformte feuerfeste Erzeugnisse - Teil 15: Bestimmung der
Wärmeleitfähigkeit nach dem Heißdraht- (parallel-) Verfahren
Méthodes d'essai pour produits réfractaires façonnés denses - Partie 15: Détermination
de la conductivité thermique par la méthode du fil chaud (parallele)
Ta slovenski standard je istoveten z: EN 993-15:2005
ICS:
81.080 Ognjevzdržni materiali Refractories
SIST EN 993-15:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 993-15:2005
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SIST EN 993-15:2005
EUROPEAN STANDARD
EN 993-15
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2005
ICS 81.080 Supersedes EN 993-15:1998
English version
Methods of test for dense shaped refractory products -
Determination of thermal conductivity by the hot-wire (parallel)
method
Méthodes d'essai pour produits réfractaires façonnés Prüfverfahren für dichte geformte feuerfeste Erzeugnisse -
denses - Partie 15: Détermination de la conductivité Teil 15: Bestimmung der Wärmeleitfähigkeit nach dem
thermique par la méthode du fil chaud (parallèle) Heißdraht- (parallel-) Verfahren
This European Standard was approved by CEN on 21 March 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 993-15:2005: E
worldwide for CEN national Members.
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SIST EN 993-15:2005
EN 993-15:2005 (E)
Contents page
Foreword.3
1 Scope .5
2 Terms and definitions .5
3 Principle.5
4 Apparatus .6
5 Test pieces .8
6 Procedure .9
7 Assessment of results .11
8 Calculation and expression of results.11
9 Test report .13
Annex A (informative) Example of the determination of thermal conductivity.14
Bibliography .17
2
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SIST EN 993-15:2005
EN 993-15:2005 (E)
Foreword
This document (EN 993-15:2005) has been prepared by Technical Committee CEN/TC 187 “Refractory
products and materials”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2005, and conflicting national standards shall be withdrawn
at the latest by November 2005.
This document supersedes EN 993-15:1998.
EN 993 Methods of test for dense shaped refractory products consists of 20 Parts as follows:
Part 1: Determination of bulk density, apparent porosity and true porosity
Part 2: Determination of true density
Part 3: Test methods for carbon-containing refractories
Part 4: Determination of permeability to gases
Part 5: Determination of cold crushing strength
Part 6: Determination of modulus of rupture at ambient temperature
Part 7: Determination of modulus of rupture at elevated temperatures
Part 8: Determination of refractoriness-under-load
Part 9: Determination of creep in compression
Part 10: Determination of permanent change in dimensions on heating
Part 11: Determination of resistance to thermal shock (ENV)
Part 12: Determination of pyrometric cone equivalent (refractoriness)
Part 13: Specification for pyrometric reference cones for laboratory use
Part 14: Determination of thermal conductivity by the hot-wire (cross-array) method
Part 15: Determination of thermal conductivity by the hot-wire (parallel) method
Part 16: Determination of resistance to sulphuric acid
Part 17: Determination of bulk density of granular materials by the mercury method with vacuum
Part 18: Determination of bulk density of granular materials by the water method with vacuum
Part 19: Determination of thermal expansion by a differential method
Part 20: Determination of resistance to abrasion at ambient temperature
3
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SIST EN 993-15:2005
EN 993-15:2005 (E)
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.
4
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SIST EN 993-15:2005
EN 993-15:2005 (E)
1 Scope
This European Standard describes a hot-wire (parallel) method for the determination of thermal conductivity of
refractory products and materials. It is applicable to dense and insulating shaped products and to powdered or
granular materials (see 6.2), for thermal conductivities of less than 25 W/m.K. The limits are imposed by the
thermal diffusivity of the test material and therefore by the dimensions of the test pieces; higher thermal
conductivities can be measured if larger pieces are used. Electrically conducting materials cannot be
measured.
NOTE 1 The thermal conductivity of products with a hydraulic or chemical bond can be affected by the appreciable
amount of water that is retained after hardening or setting and is released on firing. These materials may therefore require
pre-treatment; the nature and extent of such pre-treatment and the period for which the test piece is held at the
measurement temperature as a preliminary to carrying out the test, are details that are outside the scope of this standard
and should be agreed between the parties concerned.
NOTE 2 In general it is difficult to make measurements on anisotropic materials and the use of this method for such
materials should also be agreed between the parties concerned.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
thermal conductivity, λ
density of heat flow rate divided by the temperature gradient, in units of watt per metre Kelvin (W/m.K)
2.2
thermal diffusivity, a
λ
a =
ρ.c
p
where:
λ is the thermal conductivity
ρ is the bulk density
c is the specific heat capacity at constant pressure per weight
p
2 -1
NOTE Thermal diffusivity is expressed in units of square metre per second (m s )
2.3
power, P
rate of energy transfer, in watts (W)
3 Principle
The hot-wire method (parallel) is a dynamic measuring procedure based on the determination of the
temperature increase against time at a certain location and at a specified distance from a linear heat source
embedded between two test pieces.
5
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SIST EN 993-15:2005
EN 993-15:2005 (E)
The test pieces are heated in a furnace to a specified temperature and maintained at that temperature.
Further local heating is provided by a linear electrical conductor (the hot wire) that is embedded in the test
piece and carries an electrical current of known power that is constant in time and along the length of the test
piece.
A thermocouple is fitted at a specified distance from the hot wire; the thermocouple leads running parallel to
the wire (see Figure 1). The increase in temperature as a function of time, measured from the moment the
heating current is switched on, is a measure of the thermal conductivity of the material from which the test
pieces are made.
4 Apparatus
4.1 Furnace, electrically heated, capable of taking one or more test assemblies (see 5.1) up to a maximum
temperature of 1 250 ºC. The temperature at any two points in the region occupied by the test pieces shall not
differ by more than 10 K. The temperature measured on the outside of the test assembly during a test (of
duration about 15 min) shall not vary by more than ± 0,5 K, and shall be known with an accuracy of ± 10 K.
4.2 Hot wire, preferably of platinum or platinum-rhodium, with a minimum length equivalent to that of the
test piece. . The voltage taps should be located in the test piece with a length between the taps of about
200 mm known to the nearest ± 0,5 mm.
Both ends of the hot wire are attached to the power source and the voltage taps to the digital multimeter (4.5).
The wires to the power source may also be a continuation of the hot wire itself and shall have the same
diameter as the wire within the assembly. The wires to the digital multimeter shall be of a diameter not greater
than that of the hot wire when within the assembly. Leads outside the assembly shall consist of two or more
tightly twisted wires of 0,5 mm diameter. The current lead connections external to the furnace shall be made
with heavy gauge cable.
4.3 Power supply, to the hot wire (4.2), which shall be stabilized a.c. or d.c., but preferably a.c., and shall
not vary in power by more than 2 % during the period of measurement.
A power supply to the hot wire of at least 250 W/m is required. This is equivalent to 50 W between the voltage
taps for a distance of 200 mm.
4.4 Differential platinum/platinum-rhodium thermocouple, (Type R: platinum 13 % rhodium/platinum
thermocouple or Type S: platinum 10% rhodium/platinum thermocouple, see Table 1) formed from a
measurement thermocouple and a reference thermocouple connected in opposition (see Figure 1). The leads
of the measurement thermocouple shall run parallel to the hot wire at a distance of 15 mm ± 1 mm (see
Figure 2). The output of the reference thermocouple shall be kept stable by placing it between the top outer
face of the upper test piece and a cover of the same material as the test piece (see Figure 1). The diameter of
the measurement thermocouple wires shall be the same as that of the hot wire and the wires of both
thermocouples shall be long enough to extend outside the furnace where connections to the measuring
apparatus shall be made by wire of a different type. The external connections of the thermocouple shall be
isothermal.
An insulating layer may be inserted between the cover and the upper test piece.
NOTE Base metal thermocouples can be used at temperatures below 1 000 ºC.
6
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SIST EN 993-15:2005
EN 993-15:2005 (E)
1
2
3
4
6
5
Key
1 Cover
7
2 Reference thermocouple
3 Optional insulating layer
4 Test piece
5 Measurement circuit
8
6 Measurement thermocouple
7 Test piece
8 Heating circuit
9
9 Voltage taps
Figure 1 — Location of heating circuit and measurement circuit (differential thermocouple circuit)
3
2
1
4
Key
1 Temperature/time registration
PQ
device
5
2 Cover
3 Reference thermocouple
4 Measurement thermocouple
V
5 Hot wire
6
6 Voltmeter
A
7
7 Ammeter
8 Power source
PQ = Hot-wire measurement length
8
Figure 2 — Measurement arrangement
7
15 mm
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SIST EN 993-15:2005
EN 993-15:2005 (E)
4.5 Digital multimeter, used for measuring the current in the hot wire and the voltage drop across it, and
capable of measuring both to an accuracy of at least ± 0,5 %.
4.6 Data acquisition system, consisting of a temperature-time registration device with a sensitivity of at
least 2 µV/cm or 0,05 µV/Digit, or a temperature measurement of 0,01 K or better and with a time resolution
better than 0,5 s.
4.7 Containers, (for use if the test is performed on powdered or granular material), having internal
dimensions equal to those of the solid test assembly specified in Clause 5, so that the test assembly shall
consist of two sections as specified in 5.1. The bottom container shall have four sides and a base, and the top
container shall have four sides only, plus a detachable cover (see Figure 3).
NOTE Containers should be of a material that will not react with the test piece at the test temperature and should not
be electrically conducting.
1
2
3
Key
1 Cover
4
2 Reference thermocouple
3 Containers
4 Measurement thermocouple
5
5 Hot wire
Figure 3 — Container with hot wire and thermocouple laid on it
5 Test pieces
5.1 Dimensions
Each test assembly shall consist of two identical test pieces, not less than 200 mm x 100 mm x 50 mm in size.
NOTE 1 It is recommended that the size of each test piece be 230 mm x 114 mm x 64 mm or
230 mm x 114 mm x 76 mm. Standard-size bricks can then be used as the pieces forming the test assembly, subject to
the requirements of 5.2.
NOTE 2 The limits of this method are imposed by the dimensions of the test pieces. With larger test pieces, higher
values of thermal conductivity can be measured. The distance between the hot wire and thermocouple should be
extended to the same ratio as the test pieces. For example, with a test piece 230 mm x 180 mm x 95 mm, a thermal
conductivity of about 40 W/m.K can be measured.
8
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SIST EN 993-15:2005
EN 993-15:2005 (E)
5.2 Surface flatness
The surfaces of the two test pieces forming the test assembly which are in contact with each other shall, if
necessary, be ground so that the deviation from flatness between two points not less than 100 mm apart is not
more than 0,2 mm.
5.3 Grooves in dense materials
In dense materials, grooves to accommodate the hot wire and the measurement thermocouple shall be
machined in the lower face of the test assembly (see Figure 4). The width and depth of the grooves shall
permit the arrangement shown in Figure 4 to be achieved.
The faces of the test piece shall be parallel to the nearest ± 1 mm.
Dimensions in millimetres
1
15
Key
1 Test piece
2 Grooves with
hot wire and
thermocouple
2 2
Figure 4 — Symmetrical embedding of hot wire and thermocouple in test pieces (where required)
6 Procedure
6.1 Arrange the test assembly ready for testing. Place the hot wire (4.2) and the measurement
thermocouple (4.4) between the two test pieces, with the hot wire along the centre line of the brick faces in
contact with each other. Cement them into the grooves where appropriate, using a cement made from finely
ground test material mixed with a small amount
...
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