DIN EN ISO 8894-1-2010 Refractory materials - Determination of thermal conductivity - Part 1 Hot-wire methods (cross-array and resistance thermometer) (ISO 8894-1 2010) German vers.pdf

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1、October 2010 Translation by DIN-Sprachendienst.English price group 12No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).IC

2、S 81.080!$kTp“1724977www.din.deDDIN EN ISO 8894-1Refractory materials Determination of thermal conductivity Part 1: Hot-wire methods (cross-array and resistance thermometer)(ISO 8894-1:2010)English translation of DIN EN ISO 8894-1:2010-10Feuerfeste Werkstoffe Bestimmung der Wrmeleitfhigkeit Teil 1:

3、Heidrahtverfahren (Kreuzverfahren und Widerstandsthermometer-Verfahren)(ISO 8894-1:2010)Englische bersetzung von DIN EN ISO 8894-1:2010-10Matriaux rfractaires Dtermination de la conductivit thermique Partie 1: Mthodes du fil chaud (croisillon et thermomtre rsistance) (ISO 8894-1:2010)Traduction angl

4、aise de DIN EN ISO 8894-1:2010-10SupersedesDIN EN 993-14:1998-06www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 24 pages10.10 2 A comma is used as the decimal marker. National foreword This standard has been prepared by Technical Commit

5、tee ISO/TC 33 “Refractories” in collaboration with Technical Committee CEN/TC 187 “Refractory products and materials” (Secretariat: BSI, United Kingdom). The responsible German body involved in its preparation was the Normenausschuss Materialprfung (Materials Testing Standards Committee), Working Co

6、mmittee NA 062-02-57 AA Ungeformte, dichte geformte und wrmedmmende feuerfeste Erzeugnisse und Werkstoffe. Amendments This standard differs from DIN EN 993-14:1998-06 as follows: a) the resistance thermometer method has been added as an alternative method to the cross-array method; b) schematic repr

7、esentations of the test apparatus and the location of heating circuit and measurement circuit have been replaced/added; c) the standard has been editorially revised. Previous editions DIN 51046-1: 1976-08 DIN EN 993-14: 1998-06 DIN EN ISO 8894-1:2010-10 EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE N

8、ORM EN ISO 8894-1 May 2010 ICS 81.080 Supersedes EN 993-14:1998English Version Refractory materials - Determination of thermal conductivity - Part 1: Hot-wire methods (cross-array and resistance thermometer) (ISO 8894-1:2010) Matriaux rfractaires - Dtermination de la conductivit thermique - Partie 1

9、: Mthodes du fil chaud (croisillon et thermomtre rsistance) (ISO 8894-1:2010) Feuerfeste Werkstoffe - Bestimmung der Wrmeleitfhigkeit - Teil 1: Heidrahtverfahren (Kreuzverfahren und Widerstandsthermometer-Verfahren) (ISO 8894-1:2010) This European Standard was approved by CEN on 6 May 2010. CEN memb

10、ers 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 applicati

11、on to the CEN Management Centre 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 CEN Management Centre has t

12、he same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Pola

13、nd, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by a

14、ny means reserved worldwide for CEN national Members. Ref. No. EN ISO 8894-1:2010: E2 DIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) Contents Page 1 2 3 4 5 6 7 8 9 10 Foreword .3 Scope4 Terms and definitions .4 Principle5 Apparatus.5 Test pieces .11 Procedure.12 Assessment of results 13 Precision

15、.14 Calculation and expression of results 14 Test report14 Annex A (informative) Data conversion of change in resistance to change in temperature 16 Annex B (informative) Examples of thermal conductivity measurements21 3 Foreword which is held by BSI. This European Standard shall be given the status

16、 of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2010, and conflicting national standards shall be withdrawn at the latest by November 2010. Attention is drawn to the possibility that some of the elements of this document may be the sub

17、ject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN 993-14:1998. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement th

18、is European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerlan

19、d and the United Kingdom. Endorsement notice This document (EN ISO 8894-1:2010) has been prepared by Technical Committee ISO/TC 33 “Refractories“ in collaboration with Technical Committee CEN/TC 187 “Refractory products and materials” the secretariat of The text of ISO 8894-1:2010 has been approved

20、by CEN as a EN ISO 8894-1:2010 without any modification. DIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) 1 Scope This part of ISO 8894 describes the hot-wire methods (“cross-array” and “resistance thermometer”) for the determination of the thermal conductivity of non-carbonaceous, dielectric refrac

21、tory products and materials. This methods are applicable to dense and insulating refractories (shaped products, refractory castables, plastic refractories, ramming mixes, powdered or granular materials) with thermal conductivity values less than 1,5 W/mK (“cross-array”) and less than 15 W/mK (“resis

22、tance thermometer”) and thermal diffusivity values less than 5 106m2/s. Thermal conductivity values can be determined at a room temperature up to 1 250 C. The maximum temperature (1 250 C) can be reduced by the maximum service limit temperature of the refractory, or by the temperature at which the r

23、efractory is no longer dielectric. NOTE 1 In general, it is difficult to make accurate measurements on anisotropic materials and the use of this method for such materials can be agreed between the parties concerned. NOTE 2 The thermal conductivity of products with a hydraulic or chemical bond can be

24、 affected by the appreciable amount of water that is retained after hardening or setting and is released on firing. These materials might 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 p

25、reliminary to carrying out the test, are details that are outside the scope of this part of ISO 8894 and are agreed between the parties concerned. NOTE 3 The measurement of thermal conductivity is not sufficiently uncomplicated for an engineer to expect to achieve correct results without having part

26、icular work experience and if the work is based exclusively on this standard. Sufficient experience of measuring temperatures and laboratory skills are imperative. 2 Terms and definitions For the purposes of this document, the following terms and definitions apply. 2.1 thermal conductivity density o

27、f heat flow rate divided by the temperature gradient NOTE Thermal conductivity is expressed in watts per metre kelvin (W/mK). 2.2 thermal diffusivity a thermal conductivity divided by the bulk density times the specific heat capacity NOTE 1 a = / cpDIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) 4w

28、here: is the thermal conductivity; is the bulk density; cpis the specific heat capacity at constant pressure per weight. NOTE 2 Thermal diffusivity is expressed in units of square metres per second (m2s1). 2.3 power P rate of energy transfer NOTE Power is expressed in watts (W). 3 Principle Both the

29、 hot-wire “cross-array” and “resistance thermometer” methods are dynamic measuring procedures based on the determination of the temperature increase against time of a linear heat source (hot wire) embedded between two test pieces which make up the test assembly. The test assembly is heated in a furn

30、ace to a specified temperature and maintained at that temperature. Further local heating is provided by a linear electrical conductor (the hot wire) that is symmetrically embedded in the test assembly and carries an electrical current of known power that is constant in time and along the length of t

31、he test pieces. The increase in temperature as a function of time follows a logarithmic law, and is measured and recorded from the moment the local heating current is switched on. The thermal conductivity of the test pieces is calculated using the rate of temperature increase and the power input. Fo

32、r the “cross-array“ method, the temperature increase is measured using a thermocouple that is welded to the hot wire at its centre. The thermocouple leads are perpendicular to the hot wire. For the “resistance thermometer“ method, the temperature increase is measured by using the hot wire itself as

33、both heat source and temperature sensor. An integral temperature measurement of the hot wire is carried out over the length between the voltage taps. The change in resistance of this part of the hot wire is determined. From these data, its temperature increase is calculated. The mathematical procedu

34、re is described in Annex A. 4 Apparatus NOTE A block diagram of a suggested test apparatus for the “cross-array” method is shown in Figure 1 and for the “resistance thermometer” method in Figure 2. 4.1 Furnace, electrically heated, capable of taking one or more test assemblies (see 5.1) up to the re

35、quired maximum test temperature. 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

36、 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 and a diameter not more than 0,5 mm. Both ends of the hot wire are attached to the power supply (4.4). Leads outside the assembly shall consist of two or mo

37、re tightly twisted wires of 0,5 mm diameter. The current lead connections external to the furnace shall be made of heavy gauge cable. DIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) 5Key 1 hot-wire power supply; a.c. source 1 kHz 8 heating circuit 2 reference thermocouple Tr 9 voltage taps 3 hot-wi

38、re power control unit 10 current measurement 4 test assembly 11 data acquisition system and computer 5 cold junction of thermocouples 12 absolute signal (Ti) 6 measurement thermocouple Ti 13 difference signal (Ti Tr) 7 shunt Figure 1 Block diagram of apparatus for “cross-array” method DIN EN ISO 889

39、4-1:2010-10 EN ISO 8894-1:2010 (E) 6Key 1 hot-wire power supply; a.c. 1 kHz 9 a.c. voltage measurement 2 thermocouple 10 a.c. current measurement 3 hot-wire power control unit 11 data acquisition system and computer 4 test assembly 12 absolute signal R 5 amplifier 13 difference signal R 6 voltage ta

40、ps 14 d.c.source 100 mA 7 shunt 15 resistance measurement circuit 8 heating circuit Figure 2 Block diagram of apparatus for “resistance thermometer” method DIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) 74.3 Voltage taps, made of the same material as the hot wire. The welded connections to the hot

41、 wire should be located in the test piece with a distance of about 200 mm, known to the nearest 0,5 mm. The wires shall be of a diameter not greater than that of the hot wire. Both ends of the voltage taps are attached to the hot-wire power control unit (4.6). 4.4 Power supply, to the hot wire (4.2)

42、. For the electrical heating of the hot wire during a single measurement (6.7) an adequate power supply is required. 4.4.1 For the “cross-array” method, the power supply 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 measureme

43、nt. It shall be variable between 1 W/m and 20 W/m. This is equivalent to 0,2 W to 4 W between the voltage taps for a distance of 200 mm (see 6.5, Note). 4.4.2 For the “resistance thermometer” method, the power supply shall be stabilized a.c., and shall not vary in power by more than 2 % during the p

44、eriod of measurement. It shall be variable between 1 W/m and 125 W/m. This is equivalent to 0,2 W and 25 W between the voltage taps for a distance of 200 mm (see 6.5, Note). 4.5 Equipment for the measurement of the temperature increase of the hot wire. The following arrangements for the “cross-array

45、” and “resistance thermometer” methods shall be applied. 4.5.1 “Cross-array” method. For the “cross-array” method, use a differential platinum/platinum-rhodium thermocouple (Type S: platinum 10 % rhodium/platinum thermocouple or Type R: platinum 13 % rhodium/ platinum thermocouple) formed from a mea

46、surement thermocouple (Ti) which is welded to the hot wire at its centre and a reference thermocouple (Tr) connected in opposition outside the furnace (see Figure 1). The leads of the measurement thermocouple shall run perpendicular to the hot wire. The output of the reference thermocouple shall be

47、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 3). The maximum diameter of the measurement thermocouple wires shall not be greater than the diameter of the hot wire (to minimize loss of heat at the measuring

48、 point by conduction) 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. The measurement thermocouple (Ti) sha

49、ll be used to indicate the temperature of the test assembly. NOTE 1 An insulating layer can be inserted between the reference thermocouple and the upper test piece. NOTE 2 For hot wire, voltage taps and thermocouples made of base metal can be used at temperatures below 1 000 C. NOTE 3 The reference thermocouple (Tr) can be replaced if a data acquisition system with an adequate resolution is used. DIN EN ISO 8894-1:2010-10 EN ISO 8894-1:2010 (E) 8Key 1 cover 6 measurement thermocouple Ti 2 reference thermocouple Tr 7 t