1、BRITISH STANDARD BS EN ISO 8990:1996 Thermal insulation Determination of steady-state thermal transmission properties Calibrated and guarded hot box The European Standard EN ISO 8990:1996 has the status of a British Standard ICS 27.220BSEN ISO 8990:1996 This British Standard, having been prepared un
2、der the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes intoeffect on 15 December 1996 BSI 10-1998 The following BSI references relate to the work on this standard: Committee reference RHE/9 Draft for comment 87/76850 DC ISBN 0 580 26826
3、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 Building S
4、ervices 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 Association
5、) 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 following
6、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 Board
7、of Agrement) Flat Glass Manufacturers Association Institute of Refrigeration Institute of Chemical Engineers Insulation Jacket Manufacturers Federation Polyethylene Foam Insulation Association University of Salford Amendments issued since publication Amd. No. Date CommentsBSEN ISO 8990:1996 BSI 10-1
8、998 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 Text of EN ISO 8990 3 List of references Inside back coverBSEN ISO 8990:1996 ii BSI 10-1998 National foreword This British Standard has been prepared by Technical Committee RHE/9 and is the English language
9、 version of EN ISO 8990 Thermal insulation Determination of steady-state thermal transmission properties Calibrated and guarded hot box, published by the European Committee for Standardization (CEN). EN ISO 8990 was produced as a result of international discussions in which the United Kingdom took a
10、n 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. Cross-reference Publicatio
11、n referred to Corresponding British Standard EN ISO 7345:1995 BS EN ISO 7345:1996 Thermal insulation Physical quantities and definitions Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN title page, pages 2 to 20, an inside back cover and a back cov
12、er. 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 STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 8990 August 1996 ICS 27.220 Descriptors: Thermal insulation, thermal insul
13、ating materials, tests, determination, thermal conductivity, thermal resistance, test equipment English version Thermal insulation Determination of steady-state thermal transmission properties Calibrated and guarded hot box (ISO 8990:1994) Isolation thermique Dtermination des proprits de transmissio
14、n thermique en rgime stationnaire Mthodes la bote chaude garde et calibre (ISO 8990:1994) Wrmeschutz Bestimmung der Wrmedurchgangseigenschaften im stationren Zustand Verfahren mit dem kalibrierten und dem geregelten Heizkasten (ISO 8990:1994) This European Standard was approved by CEN on 1995-11-11.
15、 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
16、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
17、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, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for St
18、andardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1996 Copyright reserved to CEN members Ref. No. EN ISO 8990:1996 EENISO 8990:1996 BSI 10-1998 2 Foreword The text of the International Standard from Technical Committe
19、e ISO/TC 163, Thermal insulation, of the International Organization for Standardization (ISO) has been taken over as a European Standard by Technical Committee CEN/TC 89, Thermal performance of buildings components, the secretariat of which is held by SIS. This European Standard shall be given the s
20、tatus of a national standard, either by publication of an identical text or by endorsement, at the latest by February 1997, and conflicting national standards shall be withdrawn at the latest by February 1997. According to the CEN/CENELEC Internal Regulations, the national standards organizations of
21、 the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. NOTENormative references to International Standa
22、rds are listed in annex ZA (normative). Contents Page Foreword 2 Introduction 3 Section 1. General 1.1 Scope 3 1.2 Normative reference 4 1.3 Definitions 4 1.4 Symbols, units and relationships 4 1.5 Principle 4 1.6 Limitations and sources of errors 5 Section 2. Apparatus 2.1 Introduction 9 2.2 Design
23、 requirements 9 2.3 Metering box 10 2.4 Guard box 10 2.5 Specimen frame 11 2.6 Cold side chamber 11 2.7 Temperature measurements 11 2.8 Instrumentation 12 2.9 Performance evaluation and calibration 12 Section 3. Test procedure 3.1 Introduction 14 3.2 Conditioning of specimen 14 3.3 Specimen selectio
24、n and mounting 14 3.4 Test conditions 15 3.5 Measurement periods 15 3.6 Calculations 15 3.7 Test report 15 Annex A (normative) Heat transfer at surfaces and environmental temperatures 17 Annex B (informative) Bibliography 19 Annex ZA (normative) Normative references to international publications wit
25、h their relevant European publications 20 Figure 1 Guarded hot box 6 Figure 2 Calibrated hot box 7 Figure 3 Heat flow path in specimen and frame 7 Figure 4 9 Figure 5 9EN ISO 8990:1996 BSI 10-1998 3 Section 1. General Introduction Data on the thermal transmission properties of insulants and insulate
26、d structures are needed for various purposes including judging compliance with regulations and specifications, for design guidance, for research into the performance of materials and constructions and for verification of simulation models. Many thermal insulating materials and systems are such that
27、the heat transfer through them is a complex combination of conduction, convection and radiation. The methods described in this International Standard measure the total amount of heat transferred from one side of the specimen to the other for a given temperature difference, irrespective of the indivi
28、dual modes of heat transfer, and the test results can therefore be applied to situations when that is the property required. However, the thermal transmission properties often depend on the specimen itself and on the boundary conditions, specimen dimensions, direction of heat transfer, temperatures,
29、 temperature differences, air velocities, and relative humidity. In consequence, the test conditions must replicate those of the intended application, or be evaluated if the result is to be meaningful. It should also be borne in mind that a property can only be assessed as useful to characterize a m
30、aterial, product or system if the measurement of the steady-state thermal transmission properties of the specimen and the calculation or interpretation of the thermal transmission characteristics represent the actual performance of the product or system. Further, a property can only be characteristi
31、c of a material, product or system if the results of a series of measurements on a number of specimens from several samples provide sufficient reproducibility. The design and operation of the guarded or calibrated hot box is a complex subject. It is essential that the designer and user of such appar
32、atus has a thorough background knowledge of heat transfer, and has experience of precision measurement techniques. Many different designs of the calibrated and the guarded hot box exist worldwide conforming to national standards. Continuing research and development is in progress to improve apparatu
33、s and measurement techniques. Also the variation of structures to be tested may be so great, and the requirements for test conditions so different, that it would be a mistake to restrict the test method unnecessarily and to confine all measurements to a single arrangement. Thus it is not practical t
34、o mandate a specific design or size of apparatus. 1.1 Scope This International Standard lays down the principles for the design of the apparatus and minimum requirement that shall be met for determination of the laboratory steady-state thermal transmission properties of building components and simil
35、ar components for industrial use. It does not, however, specify a particular design since requirements vary, particularly in terms of size, and also to a lesser extent in terms of operating conditions. This International Standard describes also the apparatus, measurement technique and necessary data
36、 reporting. Special components, for example windows, need additional procedures which are not included in this International Standard. Also excluded are measurements of the effect on heat flow of moisture transfer or redistribution but consideration shall be given in the design and operation of the
37、equipment as to the possible effect of moisture transfer on the accuracy and the relevance of test results. The properties which can be measured are thermal transmittance and thermal resistance. Two alternative methods are included: the calibrated hot box method and the guarded hot box method. Both
38、are suitable for vertical specimens such as walls and for horizontal specimens such as ceilings and floors. The apparatus can be sufficiently large to study full-scale components. The methods are primarily intended for laboratory measurements of large, inhomogeneous specimens, although homogeneous s
39、pecimens can, of course, also be tested, and these are necessary for calibration and validation. When testing homogeneous specimens in accordance with this International Standard, experience has shown that an accuracy within 5% can generally be achieved. However, the accuracy of each individual appa
40、ratus shall be estimated with reference homogeneous specimens of thermal conductance extending over the range to be measured using the apparatus. The estimation of accuracy for nonhomogeneous specimens will be more complex and involve an analysis of the heat flow mechanism in the particular types of
41、 inhomogeneous specimens being tested. Such analyses are not covered by this International Standard. The method does not provide for measurements where there is mass transfer through the specimen during the test.ENISO 8990:1996 4 BSI 10-1998 1.2 Normative reference The following standard contains pr
42、ovisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the p
43、ossibility of applying the most recent edition of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 7345:1987, Thermal insulation Physical quantities and definitions. 1.3 Definitions For the purposes of this International Standard
44、, the following definitions apply. 1.3.1 mean radiant temperature, T r appropriate weighting of the temperatures of surfaces “seen” by the specimen for the purpose of determining the radiant heat flow rate to the surface of the specimen (see annex A) 1.3.2 environmental temperature, T n appropriate
45、weighting of air and radiant temperatures, for the purpose of determining the heat flow rate to the surface of the specimen (see annex A) 1.4 Symbols, units and relationships The following recommended symbols are used: NOTE 1This method does not directly measure the thermal conductivity although it
46、can be derived in case of opaque, homogeneous, flat specimens using the relationship, l = d/R s . 1.5 Principle 1.5.1 General Both types of apparatus, the guarded hot box (GHB) and the calibrated hot box (CHB), are intended to reproduce conventional boundary conditions of a specimen between two flui
47、ds, usually atmospheric air, each at uniform temperature. The specimen is placed between a hot and a cold chamber in which environmental temperatures are known. i Interior, usually hot side e Exterior, usually cold side s Surface n Environmental l Thermal conductivity W/(mK) R Thermal resistance (m
48、2 K)/W U Thermal transmittance W/(m 2 K) h Surface coefficient of heat transfer W/(m 2 K) Heat flow rate W p Total power input, heating orcooling W 1 Heat flow rate through specimen W 2 Imbalance, heat flow rate parallel to specimen W 3 Heat flow rate through metering box wallsW 4 Flanking loss, hea
49、t flow rate flanking specimen W 5 Peripheral loss, heat flow rate, parallel to specimen surface at the edges of the specimen W A Area perpendicular to heat flow m 2 q Density of heat flow rate W/m 2 d Specimen thickness m T a Air temperature K T r Mean radiant temperature K T n Environmental temperature K T s Surface temperature K R s= A(T si T se )/ 1 R s= 1/h R si= A(T ni T si )/ 1 R se= A(T se T ne )/ 1 R u= 1/U U = 1 /A(T ni T ne ) 1= p 3 2for guarde
