1、BS 8491:2008Method for assessment of fire integrity of large diameter power cables for use as components for smoke and heat control systems and certain other active fire safety systemsICS 13.220.40; 29.060.20NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDPublis
2、hing and copyright informationThe BSI copyright notice displayed in this document indicates when the document was last issued. BSI 2008ISBN 978 0 580 57269 2The following BSI references relate to the work on this standard:Committee reference GEL/20/18Draft for comment 06/30152609 DCPublication histo
3、ryFirst published January 2008Amendments issued since publicationAmd. no. Date Text affectedBS 8491:2008 BSI 2008 iBS 8491:2008ContentsForeword iii1 Scope 12 Normative references 13 Terms and definitions 14 Test chamber 15 Apparatus 26 Verification procedure for the source of heat 117 Test specimens
4、 128 Test procedure 159 Test report 18AnnexesAnnex A (informative) Guidance on the provision of a suitable test chamber 19Bibliography 20List of figuresFigure 1 Schematic of the test configuration 5Figure 2 Plan view of apparatus 6Figure 3 End elevation view of apparatus 7Figure 4 Rubber bush 8Figur
5、e 5 Arrangement of holes on burner face 8Figure 6 Position of water jet device 9Figure 7 Temperature measuring arrangement 10Figure 8 Example of mounting of a larger diameter test specimen 13Figure 9 Example of mounting of a smaller diameter test specimen 14Figure 10 Basic circuit diagram 16Summary
6、of pagesThis document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 20, an inside back cover and a back cover.BS 8491:2008ii BSI 2008 This page deliberately left blank BSI 2008 iiiBS 8491:2008ForewordPublishing informationThis British Standard is published by BSI and came
7、 into effect on 31 January 2008. It was prepared by Subcommittee GEL/20/18, Fire testing, under the authority of Technical Committee GEL/20, Electric cables. A list of organizations represented on this committee can be obtained on request to its secretary.Relationship with other publications The tes
8、t method given in this British Standard is technically identical with the test method given in BS 7346-6:2005, Annex B. It is intended that when BS 7346-6:2005 is amended Annex B will be taken out.Information about this documentThe test method given in this British Standard includes subjecting the c
9、able under test to radiation via direct impingement corresponding to a constant temperature attack of 842 C, to direct mechanical impacts corresponding to a force of approximately 10 N, and to direct application of a water jet simulating a water fire fighting jet.NOTE Although this test method has c
10、hanges to accommodate the application of impacts and the water jet, it is based on the test method given in BS EN 50362, which has the constant temperature attack of 842 C. This is the same constant temperature attack as used in the test method given in BS EN 50200.BS 7346-6 specifies three fire sur
11、vival times depending upon the application of the cables: either 30 min or 60 min for life safety systems (LS), and 120 min for fire fighting systems (FF). The test method given in this British Standard includes three different test durations to allow testing of cables intended for these different a
12、pplications. It is emphasized that fire tests do not assess a fire hazard, nor can the results of fire tests alone guarantee safety. They only provide information to assist in the assessment of the suitability of a cable for a given application.Hazard warningsUse of this documentIt has been assumed
13、in the preparation of this British Standard that the execution of its provisions will be entrusted to appropriately qualified and experienced people, for whose use it has been produced.WARNING. This British Standard calls for the use of substances and/or procedures that can be injurious to health if
14、 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. The test given in this British Standard may involve the use of dangerous voltages and temperatures. Suitable precautions shoul
15、d be taken against the risk of shock, burning, fire and explosion that may be involved and against any noxious fumes that may be produced.BS 8491:2008iv BSI 2008Presentational conventionsThe provisions of this standard are presented in roman (i.e. upright) type. Its methods are expressed as a set of
16、 instructions, a description, or in sentences in which the principal auxiliary verb is “shall”.Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis publication does not purpo
17、rt 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. BSI 2008 1BS 8491:20081 ScopeThis British Standard describes a method for assessment of the fire integrity of
18、large diameter power cables for use as components for smoke and heat control systems as given in BS 7346-6, and certain other active fire safety systems. It is applicable to cables of rated voltage not exceeding 600/1 000 V and of overall diameter greater than 20 mm.2 Normative referencesThe followi
19、ng referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.BS EN 60529:1992, Specification for degrees of protection pro
20、vided by enclosures (IP code)BS EN 60584-1, Thermocouples Part 1: Reference tablesBS EN 60695-4, Fire hazard testing Part 4: Terminology concerning fire tests for electrotechnical productsBS EN ISO 13943, Fire safety VocabularyIEC 60269-3, Low-voltage fuses Part 3: Supplementary requirements for fus
21、es for use by unskilled persons (fuses mainly for household and similar applications) Examples of standardized systems of fuses A to F3 Terms and definitionsFor the purposes of this British Standard the terms and definitions given in BS EN ISO 13943 and BS EN 60695-4 apply.4Test chamberThe test shal
22、l be carried out in a suitable chamber of minimum volume 10 m3, with facilities for disposing of any noxious gases resulting from burning. Sufficient ventilation shall be available to sustain the burner flame (see 5.3) for the duration of the test.The locations of any air inlets and exhaust chimney
23、shall be such that the burner flame remains stable during the verification procedure and during the tests.NOTE 1 It might be necessary to have suitable shielding of the burner flame to ensure its stability.WARNING. The test method given in this British Standard may involve the use of dangerous volta
24、ges and temperatures. Suitable precautions should be taken against the risks of shock, burning, fire and explosion that may be involved and against any noxious fumes that may be produced.BS 8491:20082 BSI 2008The same ventilation and shielding conditions shall be used in the chamber during both the
25、verification and the test procedures.NOTE 2 Guidance on the choice of suitable chambers and on ventilation and shielding conditions is given in Annex A.The atmosphere in the chamber shall be between 10 C and 40 C at the start of each test.5 ApparatusNOTE The arrangement of the apparatus is shown in
26、Figure 1, Figure 2 and Figure 3.5.1 Test ladder, for mounting the test specimen, comprising a steel framework as shown in Figure 1. The two central vertical elements of the ladder shall be adjustable in order to accommodate test specimens of different sizes of cable. The test ladder shall be (1 200
27、100) mm long and (600 50) mm high, and the total mass of the test ladder shall be (18 1) kg. Ballast, if required, shall be placed on the test ladder.NOTE 1 Angle iron, (45 5) mm wide and (6 1) mm thick with slots cut to allow for movement of the vertical elements and the fixing of the bolts and cli
28、ps (see 7.2), has been found to be a suitable material for construction of the test ladder.The test ladder shall be fastened to a rigid support framework by four bonded rubber bushes of hardness 50 to 60 Shore A. To enable this to be done, each horizontal element of the test ladder shall be extended
29、 beyond the end vertical elements and shall have a mounting hole not more than 200 mm from each end vertical element, the exact position and diameter being determined by the particular bushes and supporting framework used. The bushes shall be fitted between the horizontal elements of the ladder and
30、the support framework, as illustrated in Figure 1 and Figure 2, so as to allow movement of the test ladder under impact.NOTE 2 A typical rubber bush is illustrated in Figure 4.5.2 Circuit continuity checking and voltage withstand arrangement, comprising a three-phase star-connected transformer, or o
31、ne or more single-phase transformers, of sufficient capacity to maintain the test voltage, up to the maximum leakage current allowable, together with a suitable load and an indicating device (e.g. a lamp).NOTE 1 Consideration should be given to the characteristics of the fuse or circuit breaker (see
32、 5.9) when selecting the power rating of the transformer.NOTE 2 A lamp would constitute both a load and an indicating device. If a load other than a lamp is used a separate indicating device would be needed, such as a bell or a buzzer. BSI 2008 3BS 8491:20085.3 Source of heat, comprising a horizonta
33、lly mounted ribbon type propane gas burner with a venturi mixer. The burner face length shall be (500 25) mm and the burner face width shall be nominally 10 mm. The face of the burner shall have three staggered rows of round holes centred on the face of the burner, 1.32 mm in diameter and drilled at
34、 3.2 mm centres, as shown in Figure 5.NOTE 1 A centre feed burner is recommended.NOTE 2 In addition to the three rows of holes specified, a row of small holes milled on each side of the burner face is permitted, to serve as pilot holes for keeping the flame burning.The flow rates of propane gas and
35、of air to the burner shall be monitored by flow meters. Mass flow meters should be used as a means of controlling accurately the input flow rates. Rotameter type flow meters may be used as an alternative but are not recommended.If rotameter type flow meters are used, correction factors shall be appl
36、ied to the readings to take account of the temperature and pressure of the propane gas and the air supply. NOTE 3 Guidance on the use of rotameter type flow meters, and the application of appropriate correction factors, is given in BS EN 50200:2006, Annex B.The volume flow rate of propane gas to the
37、 burner shall be (10 0.4) l/min, which is equivalent to a mass flow rate of (319 13) mg/s. The volume flow rate of air to the burner shall be (160 8) l/min, which is equivalent to a mass flow of (3 267 163) mg/s.NOTE 4 The mass flow rates given above have been calculated from the specified volume fl
38、ow rates at reference conditions of 100 kPa (= 1 bar) and 20 C.NOTE 5 The purity of the propane gas is not specified. Use of an industrial grade of propane gas that contains impurities is permitted provided that the burner meets the performance requirements specified in 6.4.The performance of the bu
39、rner and associated controls shall be verified using the procedure given in Clause 6. The exact burner position to be used during testing shall be determined during the verification procedure, when the values of V and H to be used shall be determined. The burner shall be rigidly fixed during the tes
40、t so as to prevent movement relative to the test specimen.For the purposes of this test, the air supplied to the burner shall have a dew point not higher than 0 C.NOTE 6 If the air is supplied from a compressor, an in-line drying facility needs to be used to achieve this.NOTE 7 The source of heat an
41、d associated controls are the same as those specified in BS EN 50362:2003, 6.4.BS 8491:20084 BSI 20085.4 Impact device, comprising a round, mild steel bar (25 0.1) mm in diameter and (600 5) mm long. The bar shall be arranged and supported so that it can pivot freely about an axis parallel to the pl
42、ane of the test ladder, which is in the same horizontal plane as, and (200 5) mm away from, the front face of the test ladder. The pivoting point shall be (400 5) mm from one end of the bar and (200 10) mm from the other end, and the bar shall be arranged so that the longer section impacts the test
43、specimen. The bar shall be arranged so that it can drop under its own weight from an angle of 60 to the horizontal to strike the midpoint of the test specimen. (See Figure 3 and Figure 6.)5.5 Water jet device, comprising a 6.3 mm hose nozzle as specified in BS EN 60529:1992, Clause 14, mounted above
44、 the test specimen at an angle of (45 5) to the vertical and at a distance of (500 25) mm from the point of impact of the impact device and secured such that the water jet strikes the test specimen at the point of impact, as shown in Figure 6.The nozzle shall be supplied with water at a flow rate of
45、 12.5 l/min via an on/off valve. The flow rate shall be measured by a volumetric method prior to the test and the water supply adjusted if necessary. The water supply pipe shall be fitted with an in-line flow meter so that the water flow rate can be monitored during the test. 5.6 Test wall, for use
46、in the verification of the source of heat, comprising a board made of non-metallic heat resisting, non-combustible material. The board shall be (900 100) mm long, (300 50) mm high and (10 2) mm thick and shall be fitted with thermocouples (see 5.7) for measuring the flame temperature of the source o
47、f heat, as illustrated in Figure 7.5.7 Two 1.5 mm diameter, mineral insulated, stainless steel sheathed thermocouples, Type K conforming to BS EN 60584-1.5.8 Timer, measuring in seconds, for measuring the test duration and timing the application of impacts to the test specimen.5.9 Fuses, 2 A, Type D
48、II, conforming to IEC 60269-3, or circuit breakers with equivalent characteristics. In case of dispute the use of fuses shall be the reference method.5.10 Metal bolts and clips, for fixing the test specimen to the test ladder, comprising two U-bolts, and P-clips made of metal strip (20 2) mm wide fo
49、r use with test specimens up to 50 mm diameter and (30 3) mm wide for use with test specimens over 50 mm diameter. All clips and bolts shall be earthed.5.00+ BSI 2008 5BS 8491:2008Figure 1 Schematic of the test configurationDimensions in millimetresKey1 Impact device2 Test ladder3 Rubber bushes4Gas burner5 Fixed vertical elements of test ladder6 Adjustable vertical elements of test ladder7 Rigid support frameworkP Plane of adjustment1253537424004004001 200 1
