1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58Part 3: Classification and method of test for external fire exposure to roofsICS 13.220.50Fire test
2、s on building materials and structures BRITISH STANDARDBS 476-3:2004Incorporating Amendments Nos. 1 and 2BS 476-3:2004This British Standard was published under the authority of the Standards Policy and Strategy Committee on 14 June 2004 BSI 2007First published June 1958Second edition November 1975Th
3、ird edition June 2004The following BSI references relate to the work on this British Standard: Committee reference FSH/22/8Draft for comment 03/109613ISBN 0 580 43794 9BRE Building Research EstablishmentBRE/LPC LaboratoriesBritish Rigid Urethane Foam Manufacturers AssociationConcrete Tile Manufactur
4、ers AssociationEurisol (UK Mineral Wool Association)Fibre Cement Manufacturers Association Ltd.Flat Glass Manufacturers AssociationFlat Roofing AllianceGypsum Products Development AssociationHome OfficeMastic Asphalt Council Ltd.National Association of Rooflight ManufacturersNational Federation of R
5、oofing ContractorsNational GRP Construction and Engineering FederationOPDM Building DivisionUK Steel AssociationWarrington Fire Research CentreAmendments issued since publicationAmd. No. Date Comments16169 18 January 2006 Amendment to 4.2.316924 30 April 2007 See forewordCommittees responsible for t
6、his British StandardThe preparation of this British Standard was entrusted by Technical Committee FSH/22, Fire resistance tests, to Subcommittee FSH/22/8, Test procedures for external fire exposure to roofs, upon which the following bodies were represented: Association of British Roofing Felt Manufa
7、cturersBS 476-3:2004 BSI 2007ContentsPageCommittees responsible Inside front coverForeword ii1Scope 12 Normative references 13 Terms and definitions 14 Classification 15 Three stage test method incorporating burning brands, wind and supplementary radiant heat 2Annex A (informative) Apparatus for roo
8、f test 6Annex B (informative) Intensity of radiated heat on specimen 10Figure A.1 Typical roof test apparatus 6Figure A.2 Instrument locations for the calibration element 7Figure A.3 Specimen holder 8Table B.1 Intensity of radiated heat 10Annex C (normative) The testing and classification of roof li
9、ghts, roof windows and integrated panels for external fire exposure 10iBS 476-3:2004iiThe start and finish of text introduced or altered by amendment is indicated in the text by tags !“. Tags indicating changes to text carry the number of the amendment. For example, text altered by Amendment No. 1 i
10、s indicated by !“.The tests described in this part of BS 476 are designed to give information concerning the hazard that exists of fires spreading to the roof of a building from a nearby fire outside the building itself. The tests are not concerned with the behaviour of a roof when subjected to the
11、effects of fire on its underside.A preliminary test is made in which a specimen section of the roof is subjected to the effects of flame in the absence of radiation. Unless the specimen is so affected by this test that it is obvious it would not pass the principal tests, i.e. the penetration and the
12、 spread of flame tests, these are then carried out using the radiated heat apparatus.When subjected to the penetration test, specimens are exposed to radiation of intensity 12 kW/m2measured on the surface of the specimen. This can be regarded as, for example, the intensity incident on a roof 7.6 m a
13、bove ground level from a fire 13.7 m away in a building with a facade of 15.2 m 15.2 m and 50 % window openings. Because wind will tend to carry any surface flames through any fissures in a roof, provision is made in the test to simulate the effect of a wind of 6.7 m/s (15 miles per hour) by applyin
14、g suction to the lower side of the roof specimen during the test.In the spread of flame test, however, the intensity of radiation varies over the exposed surface of the specimen. The distance to which the fire spreads downwards over the specimen thus gives a measure of the minimum intensity required
15、 to ignite the surface when a small ignition source such as a brand is present. NOTE This intensity can be interpreted as being equivalent to the distances given in Table B.1, between an exposed roof 7.6 m above ground level and a burning building with a facade 15.2 m 15.2 m and 50 % window openings
16、.This British Standard calls for the use of substances and/or procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at any stage.This publication doe
17、s not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, pages i and ii, The BS
18、I copyright notice displayed in this document indicates when the document was last issued.pages 1 to 11 and a back cover.ForewordThis Part of BS 476-3 has been prepared by Subcommittee FSH/22/8. It is based on BS 476-3:1958 and it supersedes BS 476-3:1975 which is withdrawn. BSI 2007BS 476-3:20041 S
19、copeThe tests given in this British Standard are designed to enable measurement of:a) capacity of a representative section of a roof to resist penetration by fire when the external surface is exposed to radiation and flame; andb) distance of the spread of flame on the outer surface of the roof cover
20、ing under certain conditions.Roofs are graded according to the angle at which they are tested, the time for which they resist penetration by fire, and the distance of superficial spread of flame on their external surface.2 Normative referencesThe following referenced documents are indispensable for
21、the application of this document. For dated references, only the reference cited applies. For undated references, the latest edition of the referenced document (including any amendments).BS EN 13238, Reaction to fire tests for building products Conditioning procedures and general rules for selection
22、 of substrates.BS EN 13501-1, Fire classification of construction products and building elements Part 1: Classification using test data from reaction to fire tests.3 Terms and definitionsFor the purpose of this British Standard, the following terms and definitions apply.3.1 penetration by fireappear
23、ance of glowing or flaming on the underside of the specimen other than that of the test flameNOTE In the text, this term has been shortened to “penetration”.3.2 non-combustibleproduct which is reaction to fire Euroclass A1, as described in BS EN 13501-14 Classification4.1 Roof systemRoof systems sha
24、ll be designated by the letters EXT. F. or EXT. S. to indicate whether the test results apply to a flat (horizontal) or an inclined roof system, respectively.4.2 Fire resistance of roof system4.2.1 Coding systemRoof systems subject to conditions of external fire shall be classified according to both
25、 the time of penetration and the distance of spread of flame along their external surface.Each category designation shall consist of two letters, e.g. AA, AC, BB, these being determined as specified in 4.2.2 and 4.2.3.4.2.2 Fire penetration (first letter)A. Those specimens that have not been penetra
26、ted within one hour.B. Those specimens that are penetrated in not less than 30 min.#An additional test for rooflights is given in Annex C.$ #NOTE For special roof pitch applications at other specified angles, the test results need no such designation. $ BSI 20071C. Those specimens that are penetrate
27、d in less than 30 min.D. Those specimens that are penetrated in the preliminary flame test.BS 476-3:20044.2.3 Spread of flame (second letter)A. Those specimens on which there is no spread of flame.!B. Those specimens on which the spread of flame is less than or equal to 533 mm, with averaged results
28、 rounded up or down to whole number, as normally practised.C. Those specimens on which the spread of flame is greater than 533 mm, with averaged results rounded up or down to whole number, as normally practised.“D. Those specimens that continue to burn for five minutes after the withdrawal of the te
29、st flame or spread more than 381 mm across the region of burning in the preliminary test.4.2.4 Suffix “X” Attention shall be drawn to dripping from the underside of the specimen, any mechanical failure, and any development of holes, by adding a suffix “X” to the designation to denote that one or mor
30、e of these took place during the test.EXAMPLE 1 EXT. F. AA is a flat roofing system with one hour fire penetration resistance on which there was no spread of flame.EXAMPLE 2 EXT. S. CCX is an inclined roofing system with less than 30 min fire penetration resistance, on which the spread of flame exce
31、eded 533 mm and further deterioration took place.5 Three stage test method incorporating burning brands, wind and supplementary radiant heat5.1 Apparatus5.1.1 Brands, comprising a simulated town gas flame (55.2 % hydrogen, 27.4 % natural gas, 17.4 % nitrogen), (230 10) mm long from a (9.5 0.1) mm di
32、ameter orifice that shall be set prior to application on the test specimen.5.1.2 Wind. Provision shall be made in the test to simulate the effect of a wind speed of 6.7 m/s, generated by applying suction to the lower side of the roof specimen. Apparatus shall be provided, capable of reducing the pre
33、ssure on the underside of the specimen by (1.5 0.1) mm of water below that on the upper side, for the duration of the test. The suction under the specimen shall be measured. An inclined tube manometer may be used for this purpose.5.1.3 Radiant panel, (915 5) mm square. It shall be provided capable o
34、f being supported either at an angle of 45 or horizontal according to the test required, and shall comprise four (300 5) mm square surface combustion panels with their centres arranged at the corners of a square of (480 5) mm side (see Figure A.1).The radiation intensity incident on the specimen sha
35、ll be established with the radiant panel in the test position and the calibration element set at a perpendicular distance of (585 5) mm from the radiant panels. The radiant panels shall be capable of providing a total heat flux distribution on the surface of the calibration element such that the hea
36、t flux at the four major axes, as shown in Figure A.2, is (12 1.5) kW/m2, when all four radiant panels are used for the penetration test (stage 3, see 5.7.3).When required for the spread of flame test (stage 2, see 5.7.2) the heat flux distribution on the surface of the calibration element shall be
37、such that the heat flux at the four major axes, as shown in Figure A.2, is as follows:a) locations 1 and 2: (8.5 1.0) kW/m2;b) locations 3 and 4: (3.5 1.0) kW/m2.A 25 mm diameter Schmit Boelter heat flux meter, with a design range of (0 50) kW/m2shall be used to establish the heat flux distribution
38、on the surface of the calibration element. The target receiving radiation from the radiant panels shall be flat, circular and coated with a durable matt black finish. The target shall be water cooled. Radiation shall not pass through any window before reaching the target. The instrument shall be rob
39、ust, simple to set up and use, and stable in calibration. The instrument shall have an accuracy 2 BSI 2007of within 3 % and a repeatability within 0.5 %.The calibration of the heat flux meter shall be checked by comparison with two instruments of the same type as the working heat flux meter and of s
40、imilar range, held as reference standards and not used for any other purpose. One of the reference standards shall be fully calibrated at a competent laboratory at yearly intervals.BS 476-3:20045.1.4 Calibration element, consisting of a smooth, flat (20 2) mm thick board of calcium silicate material
41、 having the dimensions (840 10) mm square and a density of (870 100) kg/m3.5.1.5 Timing device, with an accuracy of 5 s over 24 h.5.2 CalibrationEach time the radiant panel is ignited, achieve stable conditions and adjust the radiant panel to obtain a total heat flux distribution on the surface of t
42、he calibration element as specified in 5.1.3. The minimum period of time of stabilization for calibration of the radiant panel shall be 60 min.5.3 Test conditions5.4 Test specimen5.4.1 Number of test specimens5.4.1.1 Preliminary ignition test with burning brands (stage 1) One specimen shall be teste
43、d.5.4.1.2 Spread of flame test with burning brands and supplementary radiant heat (stage 2)Three specimens shall be tested.5.4.1.3 Penetration test with burning brands, wind and supplementary radiant heat (stage 3)Three specimens shall be tested.5.4.2 Construction of specimensApply each test to a sp
44、ecimen of the roof structure (840 10) mm square. The specimens shall be representative of the complete “end use” roof construction including at least one specimen of any joints used in each of the materials to be tested. Where necessary the specimen shall be made rigid by providing a frame at the bo
45、undaries of the specimen constructed from non-combustible materials. Any gaps between the specimen and the frame shall be sealed with mortar (3:1 sand:cement mix) to provide an air seal. The specimen and its frame shall also form an air seal with the specimen cover of the test apparatus. See Figure
46、A.1 and Figure A.3.5.5 ConditioningCondition the specimens in accordance with BS EN 13238. Erect and test them as soon as possible after leaving the conditioning atmosphere. The time between leaving the conditioning atmosphere and testing shall not exceed four hours.5.6 Test environmentCarry out the
47、 testing in a draught-free area. The temperature in the enclosure shall be (20 10) C prior to the fire test. If any measures are taken to remove products of combustion from the test laboratory, they 5.1.6 Specimen holder. A metal specimen cover with a #georgian polished wired glass observation windo
48、w$is fixed to the framing (Figure A.1 and Figure A.3) and a non-combustible material is laidaround the sides of the specimen frame to provide an air seal when the specimen is placed in position. Anysmall holes around the edges of specimen and its frame shall be sealed with mortar (3:1 sand:cement mi
49、x).#Mount the test specimens: a) at an angle of 45, for an inclined test; b) horizontally, to represent flat roofs; or requested by the sponsor for limited use. The classification so obtained shall only apply to the roof specimen when used at the special angle of pitch. $ Text deleted# $c) at a selected unique angle of pitch, to meet the requirements of a special roof pitch application, where BSI 20073shall be in operation during the calibration period and maintained d
