BS EN ISO 8497-1997 Thermal insulation - Determination of steady-state thermal transmission properties of thermal insulation for circular pipes《隔热 测定圆管隔热层的稳态热传输性能》.pdf

1、BRITISH STANDARD BS EN ISO 8497:1997 Thermal insulation Determination of steady-state thermal transmission properties of thermal insulation for circular pipes The European Standard EN ISO 8497:1996 has the status of a British Standard ICS 27.220BS EN ISO 8497:1997 This British Standard, having been

2、prepared under the directionof the Engineering SectorBoard, was published underthe authority of the Standards Board and comes into effect on 15 January 1997 BSI 12-1998 The following BSI references relate to the work on this standard: Committee reference RHE/9 Draftfor comment 88/73462 DC ISBN 0 580

3、 26907 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee RHE/9, Thermal insulating materials, upon which the following bodies were represented: Autoclaved Aerated Concrete Products Association Chartered Institution of Bui

4、lding Services Engineers Concrete Block Association Cork Industry Federation Cranfield University Department of Health Department of the Environment (Building Research Establishment) Department of Trade and Industry (National Physical Laboratory) Electricity Association Eurisol (UK Mineral Wool Asso

5、ciation) European Phenolic Foam Association Gypsum Products Development Association Power Generation Contractors Association PGCA (BEAMA Ltd.) Royal Institute of British Architects Thermal Insulation Manufacturers and Suppliers Association (TIMSA) Thermal Insulations Contractors Association The foll

6、owing bodies were also represented in the drafting of the standard, through subcommittees and panels: Aggregate Concrete Block Association Association of Lightweight Aggregate Manufacturers British Ceramic Research Ltd. British Precast Concrete Federation Ltd. Department of the Environment (British

7、Board of Agrment) Flat Glass Manufacturers Association Institute of Refrigeration Institution of Chemical Engineers Insulation Jacket Manufacturers Federation Polyethylene Foam Insulation Association University of Salford Amendments issued since publication Amd. No. Date CommentsBS EN ISO 8497:1997

8、BSI 12-1998 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Definitions 3 4 Symbols and units 5 5 Requirements 5 6 General considerations 6 7 Apparatus 7 8 Test specimens 11 9 Procedure 12 10 End cap correc

9、tions 13 11 Calculations 15 12 Test precision and accuracy 15 13 Test report 16 Annex A (informative) Bibliography 17 Annex ZA (normative) Normative references to international publicationswiththeir relevant European publications 18 Figure 1 Guarded and apparatus 7 Figure 2 Calibrated or calculated

10、end apparatus 9 Figure 3 Nukiyama correction 15BS EN ISO 8497:1997 ii BSI 12-1998 National foreword This British Standard has been prepared by Technical Committee RHE/9 and is the English language version of ENISO8497:1996 Thermal insulation Determination of steady-state thermal transmission propert

11、ies of thermal insulation for circular pipes published by the European Committee for Standardization (CEN). It is identical with ISO8497:1994 published by the International Organization for Standardization. ISO 8497 was produced as a result of international discussions in which the United Kingdom to

12、ok an active part. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This

13、document comprises a front cover, an inside front cover, page i and ii, theENISO title page, pages 2 to 18 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover.EUROPEAN S

14、TANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 8497 August 1996 ICS 27.220 Descriptors: Thermal insulation, pipes (tubes), tests, determination, thermal properties, thermal conductivity, thermal resistance, thermal measurement. English version Thermal insulation Determination of steady-state thermal

15、 transmission properties of thermal insulation for circular pipes (ISO 8497:1994) Isolation thermique Dtermination des propritsrelatives au transfert de chaleur en rgime stationnaire dans les isolants thermiques pour conduites (ISO 8497:1994) Wrmeschutz Bestimmung der Wrmetransporteigenschaften im s

16、tationren Zustand von Wrmedmmungen fr Rohrleitungen (ISO 8497:1994) This European Standard was approved by CEN on 1995-11-11. 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 w

17、ithout 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 languag

18、e 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, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, I

19、taly, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref

20、. No. EN ISO 8497:1996 EEN ISO 8497:1996 BSI 12-1998 2 Foreword The text of the International Standard from Technical Committee ISO/TC163, Thermal insulation, of the International Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC89, Therm

21、al performance of buildings components, the secretariat of which is held by SIS. 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 February1997, and conflicting national standards shall be withdrawn

22、 at the latest by February1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherla

23、nds, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. NOTENormative references to International Standards are listed in annexZA (normative).EN ISO 8497:1996 BSI 12-1998 3 Introduction The thermal transmission properties of pipe insulation generally have to be determined using pip

24、e test apparatus rather than flat specimen apparatus such as the guarded hot plate or the heat flow meter apparatus, if results are to be representative of end-use performance. Insulation material formed into flat sheets often has different internal geometry from that of the same material formed int

25、o cylindrical shapes. Furthermore, properties often depend significantly upon the direction of heat flow in relation to inherent characteristics such as fibre planes or elongated cells: thus flat specimen one-dimensional heat flow measurements may not necessarily be representative of the two-dimensi

26、onal radial heat flow encountered in pipe insulation. Another consideration is that commercial insulations for pipes are often made with the inside diameter slightly larger than the outside diameter of the pipe, otherwise manufacturing tolerances may result in an imperfect fit on the pipe, thus crea

27、ting an air gap of variable thickness. In those cases where end-use performance data rather than material properties are to be determined, the insulation is mounted on the test pipe in the same loose manner so that the effect of the air gap will be included in the measurements. This would not be the

28、 case if properties were determined in a flat plate apparatus where good plate contact is required. Still another consideration is that natural convection currents around insulation installed on a pipe will cause non-uniform surface temperatures. Such conditions will not be duplicated in a flat plat

29、e apparatus with uniform plate temperatures. NOTE 1Comparison tests on apparently similar material using both pipe apparatus and flat plate apparatus have shown varying degrees of agreement of measured thermal transmission properties. It appears that better agreement is often obtained for heavier de

30、nsity products which tend to be more uniform, homogeneous and sometimes more isotropic. For those materials which have repeatedly shown acceptable agreement in such comparisons, the use of data from flat plate apparatus to characterize pipe insulation may be justified. As a general rule, when such a

31、greement has not been shown, the pipe test apparatus shall be used to obtain thermal transmission data for pipe insulations. 1 Scope This International Standard specifies a method for the determination of steady-state thermal transmission properties of thermal insulations for circular pipes generall

32、y operating at temperatures above ambient. It specifies apparatus performance requirements, but it does not specify apparatus design. The type of specimen, temperatures and test conditions to which this International Standard applies are specified in clauses5 and 6. 2 Normative references The follow

33、ing standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encou

34、raged 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 7345:1987, Thermal insulation Physical quantities and definitions. ISO 8301:1991, Thermal insulation D

35、etermination of steady-state thermal resistance and related properties Heat flow meter apparatus. ISO 8302:1991, Thermal insulation Determination of steady-state thermal resistance and related properties Guarded hot plate apparatus. 3 Definitions NOTE 2The geometry of pipe insulation requires specia

36、l terms not applicable to flat specimens. The word “linear” is used to denote properties based upon a unit length (in the pipe axis direction) of a specified insulation size. These linear properties, identified by the subscript “l”, are convenient since the total heat loss can then be calculated kno

37、wing the pipe length and the applicable temperature. “Linear” does not denote heat flow in the axial direction. In this International Standard, the direction of heat flow is predominantly radial. For the purposes of this International Standard, the following definitions apply. The definitions and sy

38、mbols given in the following clauses are based upon those in ISO7345 except for the linear thermal transference (3.1).EN ISO 8497:1996 4 BSI 12-1998 3.1 linear thermal transference, K l linear density of heat flow rate divided by the temperature difference between the pipe surface and the ambient ai

39、r in the steady-state condition. It relates to a specific insulation size and is a measure of the heat transferred through the insulation to the ambient atmosphere 3.2 linear thermal resistance, R l temperature difference between the pipe surface and the insulation outer surface divided by the linea

40、r density of heat flow rate in the steady-state condition. It relates to a specific insulation size and is the reciprocal of the pipe linear thermal conductance, l 3.3 linear thermal conductance, l reciprocal of the linear thermal resistance, R l , from the pipe surface to the insulation outer surfa

41、ce. It relates to a specific insulation size 3.4 surface coefficient of heat transfer, h 2 areal density of heat flow rate at the surface in the steadystate condition divided by the temperature difference between the surface and the surrounding ambient air. For pipe insulation geometry the following

42、 relation applies 3.5 thermal conductivity, l defined by the following relation specifically applicable to the pipe insulation geometry. It applies to homogeneous material in the steady-state condition and is the reciprocal of the thermal resistivity, r NOTE 3In ISO7345, the thermal conductivity is

43、also defined by the more general relation q = l grad T. NOTE 4Since the pipe surface temperature, T o , is used, the thermal conductivity will include the effect of any gap that exists between the insulation and the pipe (see6.1). 3.6 thermal resistivity, r reciprocal of the thermal conductivity, l,

44、 for a homogeneous material in the steady-state condition 3.7 areal thermal resistance, R temperature difference between the pipe surface and the insulation outer surface divided by the areal density of heat flow rate in the steady-state condition. It is the reciprocal of the areal thermal conductan

45、ce, where the surface of area A must be specified (usually the pipe surface, sometimes the insulation outer surface, or other as chosen; see note6 in 3.8) NOTE 5The more common “areal” properties, based upon unit area, are often confusing when applied to pipe insulation since the area must be chosen

46、 arbitrarily and may range from that of the pipe surface to that of the insulation outer surface. If these areal properties are computed, the area and its location used in the computation must be reported. 3.8 areal thermal conductance, reciprocal of the areal thermal resistance, R where the locatio

47、n of the surface of area A must be specified (usually the pipe surface, sometimes the insulation outer surface, or other as chosen) NOTE 6The value of , the areal thermal conductance, is arbitrary since it depends upon an arbitrary choice of the area, A. For a homogeneous material for which the ther

48、mal conductivity is defined as in3.5, the areal conductance, , is given byEN ISO 8497:1996 BSI 12-1998 5 If the area is specially chosen to be the “log mean area”, equal topL(D 2 D 0 )/In(D 2 /D 0 ) then = 2l/(D 2 D 0 ). Since (D 2 D 0 )/2 is equal to the insulation thickness measured from the pipe

49、surface, this is analogous to the relation between conductance and conductivity for flat slab geometry. Similar relations exist for the areal thermal resistance, R, defined in3.7. Since these areal coefficients are arbitrary and since the area used is often not stated, thus leading to possible confusion, it is recommended that they be used only if specified. 4 Symbols and units For the purposes of this International Standard, the following symbols and units apply. (See clause 3.) NOTE 7The subscript “|” is used t