1、BRITISH STANDARDBS 476-20:1987Incorporating Amendment No. 1.Fire tests on building materials and structures Part 20: Method for determination of the fire resistance of elements of construction (general principles)UDC 614.841.332:620.1:69.01:699.811987Incorporating Amendment No. 1 and Corrigendum No.
2、 1ICS 13.220.50BS 476-20:1987This British Standard, having been prepared under thedirection of the Fire Standards Committee, was publishedunder the authority of the Board of BSI and comes into effect on29 May 1987 BSI 12-1998The following BSI references relate to the work on this standard:Committee
3、reference FSM/1Draft for comment 84/38456 DCISBN 0 580 15897 7Committees responsible for this British StandardThe preparation of this British Standard was entrusted by the Fire Standards Committee (FSM/-) to Technical Committee FSM/1, upon which the following bodies were represented:Association of B
4、ritish Roofing Felt Eurisol (UK) Association of Manufacturers ofManufacturers Mineral Insulation FibresAssociation of Building Component Mineral Insulation FibresManufacturers Ltd. Fibre Building Board Organisation (FIDOR)Association of Structural Fire Protection Fibre Cement Manufacturers Associati
5、on Contractors and Manufacturers LimitedBritish Coal Fire Insurers Research and Testing British Fire Services Association Organisation (FIRTO)British Floor Covering Manufacturers Fire Offices Committee Association Fire Protection AssociationBritish Plastics Federation Flat Glass Manufacturers Associ
6、ationBritish Railways Board Flat Roofing Contractors Advisory BoardBritish Rigid Urethane Foam Manufacturers Gypsum Products Development AssociationAssociation Home OfficeBritish Wood Preserving Association Institution of Fire EngineersCement and Concrete Association Mastic Asphalt Council and Emplo
7、yers Chemical Industries Association FederationChief and Assistant Chief Fire Officers National Council of Building Materials Association ProducersConcrete Society National GRP Construction FederationDepartment of Education and Science RAPRA Technology Ltd.Department of the Environment for Northern
8、Royal Institute of British ArchitectsIreland Steel Construction InstituteDepartment of the Environment (Housing and Timber Research and Development Construction Industries) AssociationDepartment of the Environment (Property United Kingdom Antimony Oxide Services Agency) Manufacturers AssociationDepa
9、rtment of Transport (Marine Directorate) United Kingdom Atomic Energy AuthorityElectricity Supply Industry in England and Wood Wool Slab Manufacturers AssociationWales Yarsley Technical Centre Ltd.Engineering Equipment and Materials UsersAssociationThe following bodies were also represented in the d
10、rafting of the standard, through subcommittees and panels:Association of Builders Hardware Guild of Architectural IronmongersManufacturers Hevac AssociationBritish Steel Industry Intumescent Fire Seals AssociationDepartment of the Environment (Building National Association of Lift MakersResearch Est
11、ablishment, Fire Research Suspended Ceilings AssociationStation) Thermal Insulation Manufacturers andDoor and Shutter Association Suppliers Association (TIMSA)Electric Cable Makers ConfederationAmendments issued since publicationAmd. No. Date of issue Comments6487 April 1990 Indicated by a sideline
12、in the marginBS 476-20:1987ISBN 978 0 580 85687 7Amendments/corrigenda issued since publicationAmd. No. Date Comments6487 April 1990 Indicated by a sideline in the marginC1 April 2014 Information added to ForewordThis British Standard, having been prepared under the direction of the Fire Standards C
13、ommittee, was published under the authority of the Board of BSI and comes into effect on 29 May 1987 The British Standards Institution 2014 Published by BSI Standards Limited 2014The following BSI references relate to the work on this standard: Committee reference FSM/1 Draft for comment 84/38456 DC
14、BS 476-20:1987 BSI 12-1998 iContentsPageCommittees responsible Inside front coverForeword ii0 Introduction 11 Scope 12 Definitions 13 Test conditions 24 Test specimen 35 Selection of support and loading conditions 46 Apparatus 57 Examination of specimen 88 Preparation of specimen 89 Test procedure 8
15、10 Performance criteria 811 Expression of results 912 Test report 10Appendix A Guidance information 11Appendix B Evaluation of residual loadbearing capacity 22Appendix C Operating instructions, specimen preparation and observations 23Appendix D Hydrocarbon curve 41Figure 1 Examples of restraint 29Fi
16、gure 2 Standard temperature/time curve 33Figure 3 Specimen surface thermocouple junction and insulating pad 34Figure 4 Roving thermocouple measuring junction 35Figure 5 Typical frame for supporting the cotton pad 36Figure 6 Steel gauges for determining imperviousness 37Figure 7 Alternative jointing
17、methods for walls 38Figure 8 Pressure sensing head 39Figure 9 Furnace thermocouple assembly 40Figure 10 Thermocouple weight for resilient materials 41Publications referred to Inside back coverBS 476-20:1987i The British Standards Institution 2014BS 476-20:1987ii BSI 12-1998ForewordThis Part of BS 47
18、6 has been prepared under the direction of the Fire Standards Committee and describes the general procedures and equipment required to determine the fire resistance of elements of construction. This Part should be read together with BS 476-21, BS 476-22 and BS 476-23 as appropriate which describe th
19、e detailed procedure for the testing of individual elements of construction. The four Parts taken together constitute a complete revision of BS 476-8, which is withdrawn. However, the latter will still be made available on request, since it is referred to in building regulations and other legislativ
20、e documents.Parts 20 to 23 have been prepared in such a way that Part 20 will need to be used with the subsequent Parts described.For the purposes of these Parts, elements of construction have been categorized into three main groups:a) loadbearing elements that have a fire resistance;b) non-loadbear
21、ing elements that have a fire resistance;c) elements that make a contribution to the fire resistance of a structure.The specific requirements for the testing of these groups are described in Parts 21 to 23 respectively. Guidance and background information that will assist the designer and the testin
22、g authority to select and evaluate specimens that are more representative of situations in practice are given in appendices to the four Parts.The revision of BS 476-8 has been prepared in order to improve repeatability and reproducibility of the results obtained by more closely defining the operatin
23、g procedures and the equipment used. The main changes relate to improvements in the techniques for measuring temperature, pressure and load distribution. Following the publication of PD 6496 which analysed the differences between the requirements of BS 476-8, ISO 834, ISO 3008 and ISO 3009, and Anne
24、x 1 of the preliminary draft on an EEC Commission Directive DG 111 (document 1202, September 1977) (now replaced by EUR 8750), this revision has, where possible, adopted similar requirements to those given in the international standards, though in some cases, improvements have been made. These impro
25、vements have tended to tighten up the procedures already specified in the other standards and will therefore remain in compliance with them.One significant change in the method is the introduction of a fixedtemperature/time heating regime which assumes a notional ambient temperature rather than the
26、use of a temperature/rise curve that is related to the actual ambient temperature at the time of the test. The reasons for this change are described in Appendix A. In some cases, it has been requested that tests be carried out according to the so-called “hydrocarbon curve”. Although the heating regi
27、me specified in clause 3 is the exposure condition required by the standard, in order to avoid the possible confusion which might arise due to non-availability of a standard for such temperature/time curves, Appendix D includes for information a heating regime which has been proposed in ISO/DIS 834
28、(as a preferred option) to represent special risk requirements such as may be encountered in offshore structures, etc.A further change has been the adoption of the minimum specimen sizes specified in ISO 834. Combined with this is a greater acceptability of smaller furnaces for testing specimens of
29、elements that are, at full size, capable of being tested in smaller furnaces. Because of the diversity of furnace designs it has not been possible to define the equipment more tightly, although A.5 does give guidance on the points to be considered in any future furnace designs. This Part has, howeve
30、r, eliminated the use of oil based fuels as a method of heating a fire resistance testing furnace.BS 476-20:1987ii BSI 12-1998ForewordThis Part of BS 476 has been prepared under the direction of the Fire Standards Committee and describes the general procedures and equipment required to determine the
31、 fire resistance of elements of construction. This Part should be read together with BS 476-21, BS 476-22 and BS 476-23 as appropriate which describe the detailed procedure for the testing of individual elements of construction. The four Parts taken together constitute a complete revision of BS 476-
32、8, which is withdrawn. However, the latter will still be made available on request, since it is referred to in building regulations and other legislative documents.Parts 20 to 23 have been prepared in such a way that Part 20 will need to be used with the subsequent Parts described.For the purposes o
33、f these Parts, elements of construction have been categorized into three main groups:a) loadbearing elements that have a fire resistance;b) non-loadbearing elements that have a fire resistance;c) elements that make a contribution to the fire resistance of a structure.The specific requirements for th
34、e testing of these groups are described in Parts 21 to 23 respectively. Guidance and background information that will assist the designer and the testing authority to select and evaluate specimens that are more representative of situations in practice are given in appendices to the four Parts.The re
35、vision of BS 476-8 has been prepared in order to improve repeatability and reproducibility of the results obtained by more closely defining the operating procedures and the equipment used. The main changes relate to improvements in the techniques for measuring temperature, pressure and load distribu
36、tion. Following the publication of PD 6496 which analysed the differences between the requirements of BS 476-8, ISO 834, ISO 3008 and ISO 3009, and Annex 1 of the preliminary draft on an EEC Commission Directive DG 111 (document 1202, September 1977) (now replaced by EUR 8750), this revision has, wh
37、ere possible, adopted similar requirements to those given in the international standards, though in some cases, improvements have been made. These improvements have tended to tighten up the procedures already specified in the other standards and will therefore remain in compliance with them.One sign
38、ificant change in the method is the introduction of a fixedtemperature/time heating regime which assumes a notional ambient temperature rather than the use of a temperature/rise curve that is related to the actual ambient temperature at the time of the test. The reasons for this change are described
39、 in Appendix A. In some cases, it has been requested that tests be carried out according to the so-called “hydrocarbon curve”. Although the heating regime specified in clause 3 is the exposure condition required by the standard, in order to avoid the possible confusion which might arise due to non-a
40、vailability of a standard for such temperature/time curves, Appendix D includes for information a heating regime which has been proposed in ISO/DIS 834 (as a preferred option) to represent special risk requirements such as may be encountered in offshore structures, etc.A further change has been the
41、adoption of the minimum specimen sizes specified in ISO 834. Combined with this is a greater acceptability of smaller furnaces for testing specimens of elements that are, at full size, capable of being tested in smaller furnaces. Because of the diversity of furnace designs it has not been possible t
42、o define the equipment more tightly, although A.5 does give guidance on the points to be considered in any future furnace designs. This Part has, however, eliminated the use of oil based fuels as a method of heating a fire resistance testing furnace.BS 476-20:1987 The British Standards Institution 2
43、014This part of BS 476 is published by BSI Standards Limited, under licence from The British Standards Institution.This standard has been superseded by the current BS EN 1363-1 and BS EN 1363-2, but it has been retained based on legitimate need for the standards within non-EU markets.BS 476-20:1987
44、BSI 12-1998 iiiThe differential pressure between the furnace chamber and the laboratory has been changed slightly with respect to the magnitude, the time of application and the measuring technique. This has been done in an attempt to rationalize the pressure difference requirements for all elements
45、under test.Following the decision of the International Organization for Standardization, Technical Committee ISO/TC 92, Fire tests on building materials, components and structures, to dispense with the use of the criterion of stability (ultimate integrity) in the fire resistance testing procedures f
46、or fire doors and glazed elements (ISO 3008 and ISO 3009 respectively) it has been decided to adopt a similar principle in this revision. It is no longer required, therefore, to evaluate non-loadbearing elements (see BS 476-22) with respect to compliance with a stability requirement. In order to cla
47、rify the use of stability in respect to loadbearing elements a new term, loadbearing capacity, has been introduced in this revision (see clause 2 and Appendix A). The criterion for integrity has also been slightly modified and a new term, impermeability, has been introduced in order to clarify one a
48、spect of integrity failure.Information on the evaluation of residual loadbearing capacity is given in Appendix B.Attention is drawn to the Health and Safety at Work etc. Act 1974, and the need to ensure that the method of test described in this standard is carried out under suitable environmental co
49、nditions to provide adequate protection to personnel against the risk of fire, and/or inhalation of smoke and/or toxic products of combustion.CAUTION. The mechanical sawing of asbestos cement components attracts the provision of the Asbestos Regulations 1969. Adequate methods exist to control levels of dust during such operations and these are detailed in the Control and Safety Guides issued by the Asbestos Research Council1).A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are respons
