1、 STD.BS1 BS EN IS0 B477-ENGL 1777 1b24bb 057832b 140 M BRITISH STANDARD Thermal insulation - De termination of steady-state thermal transmission properties of thermal insulation for circular pipes The European Standard EN IS0 8497 : 1996 has the status of a British standard ICs 27.220 BS EN IS0 8497
2、 : 1997 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW STD.BSI BS EN IS0 8977-ENGL 1777 LbZLibbS 0578327 U87 Amd. No. Date The following BSI references relate to the work on this standard: BS EN IS0 8497 : 1997 Text affected This British Standard, having been prepared under t
3、he direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 16 January 1997 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee RHE/Q, Thermal insulating mat
4、erials, upon which the foilowing bodies were represented Autoclaved Aerated Concrete Products Association Chartered Institution of Building Services Engineers Concrete Block Association Cork Industry Federation Cranfield University Department of Hdth Department of the Environment (Building bearch Es
5、tablishment) Department of Tiade and Industry (National Physical Laboratory) Electricity Association Eurisol (UK Mineral Wool Association) European Phenolic Foam Association Gypsum Products Development Association Power Generation Contsactors Association (PGCA (BEAMA Ltd.) Royal Institute of British
6、 Architects Thermal insMon Manufacturers and Suppliers Association (TMSA) Thermal InsMons Contractors Association The foilowing bodies were ais0 represented in the drafting of the standard, through subcommittees and panels Aggregaix Concrete Block Association Association of Lightweight Aggregate Man
7、ufaclmes British Ceramic Research Ltd. British Precast Concrete Federation Ltd Department of the Environment (British Board of Agrment) Flat Glass Manufacturers Association institute of Refrigeration institution of Chemical Engineers Insulation Jacket Manufacturers Federation Polyethylene Foam Insul
8、ation Association University of Salford O BSI 1997 Committee reference RHE/S Draft for comment 8W3462 DC I I ISBN O 080 26907 8 I I I I _ STD-BSI BS EN ISp8q97-ENGL 1997 Lb2Libb9 0578328 TL3 BS EN IS0 8497 : 1997 Contents page Committees responsible inside hnt cover National foreword ii Foreword 2 I
9、ntroduction 2 Method 1 2 3 4 6 6 7 8 9 10 11 12 13 Scope Normative references Dennitions Symbols and units Requirements General considerations Apparatus Test specimens Procedure End cap corrections calaons Test precision and accutcy 3 3 3 5 5 6 7 11 12 14 15 16 Test report 16 Annexes ZA (normative)
10、Nonnative references to intemational publications with their Figures A (ionnative) Bibliography 18 relevant European publications 20 1 Guardedandapparatus 7 2 Calibrated or calculated end apparatus 9 3 Nukiym correction 15 O BSI 1997 i STD.BS1 BS EN IS0 g97-NGL 1777 1b24bb9 0578329 95T I- BS EN IS0
11、8497 : 1997 National foreword This British Standard has been prepared by Technid Committee RHEB and is the Engiish ianguage version of EN IS0 8497 : 1996 l7zem.d insulation -Determination of steady-state thermal tmnsrnwn pmperth of themzal insulation for circular pipes published by the European Comm
12、ittee for Standardization (CEN). It is identical with IS0 8497 : 1994 published by the Intemational Organization for Standardization. IS0 8497 was produced as a result of international discussions in which the United Kingdom took an active paransmission properties of thermal insulation for circular
13、pipes (is0 8497 : 1994) isolation thermique - Dtermination des proprits relatives au transfert de chaleur en rgime stationnaire dans les isolants thenniques pour conduites (Is0 8497 : 1994) Wrmeschutz - Bestimmung der Wamietransporteigenschaftn im stationren Zustand von Wmedmmungen fr Rohrleitungen
14、(IS0 8497 : 1994) This European Standard was approved by CEN on 199511-11. CEN members are bound to comply with the CENCENELEC Internai Regulations which stipulate the conditions for giving this European standard the status of a national standard without any alteration. Uptodate lists and bibliograp
15、hicd 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
16、 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, Gennany, Greece, Iceland, Ireland, Itay, Luxembourg, Netherlands, Norway, Portugal, Spain,
17、Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fur Normung Central Secretariat: rue de Stassart 36, B-1060 Brussels O 1996 Copyright reserved to CEN members Ref. No. EN IS0 8497 : 1996 E STD-BSI BS EN IS0 8477-ENG
18、L 1777 m 3b24bb7 0578333 508 m Page 2 EN IS0 8497 : 1996 Foreword The text of the international Standard from Technical Committee ISOK 163, Thermal insulation, of the internationai Organization for Standarwion USO) has been taken over as a European Standard by Technical Committee CENK 89, Thermai pe
19、rformance of buildings components, the secretariat of which is held by SIS. This European standard shail be given the status of a national standard, either by publicaion of an identical text or by endorsement, at the latest by February 1997, and conflicting national standards shaU be withcrawn at th
20、e latest by February 1997. According to the CENCENELEC Internal Reguiations, the nationai stasidards organizations of the following countries are bound to implement this European Standard: Ausha, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Itaiy, Luxembourg, Netherlands, No
21、rway, Portugal, Spain, Sweden, Swilzerland and the United Kingdom. NOTE. Normative references to international Standards are iisted in annex ZA (normative). Introduction The thermal transmission properties of pipe insulation generally have to be determined using pipe test apparatus rather than flat
22、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 materiai formed into flat sheets often has different internal geometzy from that of the same material formed into cylindrical shapes. Furthennore,
23、 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 onedimensional heat flow measurements may not necessarily be representaiive of the two-dimensional raid heat flow encountered in
24、pipe insulation. Another consideration is that commercial insulations for pipes are often made with the inside diameter slightly iarger than the outside diameter of the pipe, otherwise manufacturing tolerances may result in an imperfect fit on the pipe, thus creating an air gap of variable thickness
25、. In those cases where end-use performance dah 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 case if properties were determined in
26、 a flat plate apparatus where good plate contact is required Still another consideration is that natural convection currents around insulation installed on a pipe wili cause non-uniform surface temperatures. Such conditions will not be duplicated in a flat plate apparatus with uniform plate temperat
27、ures. NOTE 1. Comparison 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 density products which tend to be more
28、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 agreement has not been shown, the pipe
29、 test apparatus shall be used to obtain thermal transmission data for pipe insulations. O BSI 1997 STD-BSI BS EN IS0 LI77-ENGL 1777 Lb2Ybb7 0578332 Y49 Page 3 EN IS0 8497 : 1496 Thermal insulation - Determination of steady-state thermal transmission properties of thermal insulation for circular pipe
30、s - - 1 Scope This International Standard specifies a method for the = - - I * * determination of steady-state thermal transmission properties of thermal insulations for circular pipes vi generally operating at temperatures above ambient. It specifies apparatus performance requirements, but it does
31、not specify apparatus design. The type of specimen, temperatures and test condi- tions to which this Intemational Standard applies are specified in clauses 5 and 6. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this
32、International Standard. At the time of publica- tion, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent editions of the standards indicat
33、ed below. Members of IEC and IS0 maintain registers of cur- rently valid International Standards. IS0 73451 987, Thermal insulation - Physical qua* tities and definitions. IS0 8301 :1991, Thermal insulation - Determination of steady-state thermal resistance and related prop- erties - Heat flow meter
34、 apparatus. IS0 83021 991, Thermal insulation - Detemination of steady-stete thermal mistance and related prop erties - Guarded hot plate appamtus. 3 Definitions NOTE 2 The geometry of pipe insulation requires special terms not applicable to flat specimens. The word “linear“ is used to denote proper
35、ties based upon a unit length (in the pipe axis direction) of a specified insulation size. These lin- ear PropertieS. identified by the subscript “I“, are con- venient since the total heat loss can then be calculated knowing the pipe length and the applicable temperature. “Linear“ does not denote he
36、at 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 sym bols given in the following clauses are based upon those in IS0 7345 except fo
37、r the linear thermal transference (3.1). 3.1 linear thermal transference, 4: Linear density of heat flow rate divided by the temperature differ- ence between the pipe surface and the ambient air in the steady-state condition. It relates to a specific in- STD-BSI BS EN IS0 8497-ENGL 1997 m Lb2LibbS 0
38、578333 3811 Page 4 EN IS0 8497 : 1996 sulation size and is a measure of the heat transferred through the insulation to the ambient atmosphere. 3.2 linear thermal resistance, i?,: Temperature dif- ference between the pipe surface and the insulation outer surface divided by the linear density of heat
39、flow rate in the steady-state condition. It relates to a spe- cific insulation size and is the reciprocal of the pipe linear thermal conductance, A,. 3.3 linear thermal conductance, A,: Reciprocal of the linear thermal resistance, Ri, from the pipe surface to the insulation outer surface. It relates
40、 to a specific insulation size. . . . (3) 3.4 surface ment of heat transfer, 4: Areal density of heat flow rate at the surface in the steady- state Condition divided by the temperature difference between the surface and the surrounding ambient air. For pipe insulation geometry the following relation
41、 applies. . CP = xD2L(T2 - Ta) (4) 3.5 thermal conductivity, k Defined by the follow- ing relation specifically applicable to the pipe insu- lation geometry. lt applies to homogeneous material in the steady-state condition and is the reciprocal of the thermal resistivity, r. (5) NOTES 3 In IS0 7345,
42、 the thermal conductivity is also defined by the more general relation q = - A grad T. 4 Since the pipe surface temperature, To, is used, the thermal conductivity will include the effect of any gap that exists between the insulation and the pipe (see 6.1 1. 3.6 thermal resistivity, I. Reciprocal of
43、the thermal conductivity, A, for a homogeneous material in the steady-state condition. 3.7 amal thermal resistance, R: Temperature dif- ference 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
44、 of the areal thermal conductance, A. where the surface of area A must be specified (usually the pipe surface, sometimes the insulation outer sur- face, or other as chosen; see note 6 in 3.8). NOTE 5 The more common “areal“ properties, based upon unit area, are often confusing when applied to pipe i
45、nsulation since the area must be chosen 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 re- ported. 3.8 areal thermal conductance, A: Reciprocal of the a
46、real thermal resistance, R. where the location of the surface of area A must be specified (usually the pipe surface, sometimes the in- sulation outer surface, or other as chosen). NOTE 6 The value of A, the areal thermal conductance, is arbitrary since it depends upon an arbitrary choice of the area
47、, A. For a homogeneous material for which the thermal conductivity is defined as in 3.5, the areal conductance, A, is given by . (9) If the area is specialiy chosen to be the “log mean area“, equal to UD2 - D,)/ln(D other outside shapes are allowed but only thermal transference may then be determine
48、d. 5.2 Operating temperature The pipe may be operated at temperatures up to the maximum service temperature of the specimen or of the materials used in constructing the apparatus. The lower limit of the pipe temperature is determined by the restriction that it be sufficiently greater than the temper
49、ature of the specimen outer surface to provide the precision of measurement desired. Normally, the apparatus is operated in still air maintained at an am bient temperature of 15 OC to 35 OC, but this may be extended to other temperatures, other gases and other velocities. The outer specimen surface tem- perature may also be fixed by the use of a heated or cooled outer sheath or blanket or by the use of an additional layer of insulation. If a cold outer sheath or jacket is used, operation at low temperatures is po
