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1、BRITISH STANDARD BS 7346-4:2003 Components for smoke and heat control systems Part 4: Functional recommendations and calculation methods for smoke and heat exhaust ventilation systems, employing steady-state design fires Code of practice ICS 13.220.20 ? Licensed Copy: London South Bank University, L
2、ondon South Bank University, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 This British Standsrd was published under the authority of the Standards Policy and Strategy Committee on 29 August 2003 BSI 29 August 2003 The following BSI references relate to the work on th
3、is British Standard Committee reference FSH/25 Draft for comment 00/541350 DC ISBN 0 580 42233 X Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee FSH/25, Smoke, heat control systems and components, upon which the following
4、 bodies were represented: Association of Roof Light Manufacturers BRE/LPC Laboratories British Blind and Shutter Association Building Services Research and Information Consumer Policy Committee of BSI Fire Resistant Glass and Glazing Federation HEVAC Association Institution of Fire Engineers London
5、Fire and Emergency Planning Authority OPDM Building Regulation Division ODPM Office of the Deputy Prime Minister Smoke Vent Association Steel Window Association Co-opted members Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank Un
6、iversity, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 BSI 29 August 2003 i Contents Page Committees responsibleInside front cover Forewordii 0Introduction1 1Scope5 2Normative references5 3Terms, definitions, symbols and units6 4General recommendations14 5Calculation
7、 procedures19 6Performance recommendations22 7Interaction with other fire protection systems and other building systems40 Annex A (informative) Default value heat release rates44 Annex B (informative) The plume rising directly from the fire into a smoke reservoir44 Annex C (informative) The flow of
8、hot smoky gases out of a fire-room into an adjacent space47 Annex D (informative) The flow of hot smoky gases under a soffit projecting beyond a fire-rooms opening or window51 Annex E (informative) The spill plume56 Annex F (informative) The smoke reservoir and ventilators56 Annex G (informative) Th
9、e influence of zones of overpressure and/or zones of suction upon a SHEVS60 Annex H (informative) Deflection of free-hanging smoke barriers63 Annex I (informative) Plenum chamber67 Annex J (informative) Atrium depressurization69 Annex K (informative) The interaction of sprinklers, a SHEVS and fire-f
10、ighting actions79 Annex L (informative) The effect of a buoyant layer on the minimum pressure recommended for a pressure differential system80 Bibliography83 Figure 1 Design regions for a single-volume space19 Figure 2 Design regions for a space where there is a spill plume21 Figure 3a) Adhered plum
11、e28 Figure 3b) Free plume29 Figure 4a) Deep balcony projection30 Figure 4b) Shallow balcony projection31 Figure 5 Flow resistance through openings in an atrium39 Figure 6 Early (or premature) stratification of smoke41 Figure B.1 Limiting size of a cellular room45 Figure B.2 Smoke ventilation in a si
12、ngle-storey mall47 Figure C.1 Flow out of an opening with high balcony48 Figure C.2 Flow out of an opening with downstand and projecting balcony49 Figure D.1 Smoke spreading sideways beneath a projecting canopy or balcony52 Figure D.2 Smoke confined to a compact spill plume by channelling screens53
13、Figure D.3 Slot exhaust55 Figure F.1 Use of smoke transfer ducts in otherwise stagnant regions59 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 ii BSI 29 August 2003 Page Figure G.1 Zones of ove
14、rpressure on a roof with an outstanding structure60 Figure G.2 Assessment of hst in case of a roof with an outstanding structure and a parapet61 Figure G.3 Zones of suctions affecting the location of inlet openings62 Figure H.1 Forces acting on a deflected smoke barrier64 Figure H.2 Forces acting on
15、 a deflecting smoke barrier closing an opening66 Figure I.1 Plenum chamber68 Figure J.1 Neutral pressure plane throughflow ventilation70 Figure J.2 Neutral pressure plane exhaust larger than inlet71 Figure J.3 Neutral pressure plane above highest leaky storey72 Figure J.4 Principles of hybrid smoke
16、ventilation system mass flow-based76 Figure J.5 Principles of hybrid smoke ventilation system temperature-based78 Figure L.1 The neutral pressure plane and layer buoyant pressure81 Table 1 Default values of design fires24 Table 2 Minimum clear height above escape routes25 Table 3 Convective heat flu
17、x at the room opening26 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 BSI 29 August 2003 iii Foreword This part of BS 7346 has been prepared by Technical Committee FSH/25. The other parts compr
18、ising BS 7346 are: Part 1: Specification for natural smoke and heat exhaust ventilators; Part 2: Specification for powered smoke and heat exhaust ventilators; Part 3: Specification for smoke curtains. The above three standards are eventually to be replaced by EN 12101, Smoke and heat control systems
19、, consisting of the following parts: Part 1: Specification for smoke barriers Recommendations, test methods; Part 2: Specification for natural smoke and heat exhaust ventilators; Part 3: Specification for powered smoke and heat exhaust ventilators; Part 4: Smoke and heat control installations Kits;
20、Part 6: Functional requirements and calculation methods, components, installation and testing procedures for pressure differential smoke control systems; Part 7: Smoke control ducts; Part 8: Smoke control dampers; Part 9: Power supply equipment; Part 10: Control equipment. EN 12101 forms part of a s
21、eries of European Standards, which are planned to cover: CO2 systems (EN 12094); sprinkler systems (EN 12259); powder systems (BS EN 12416); explosion protection systems (BS EN 26184); foam systems (pr EN 13565); hydrant and hose reel systems (BS EN 671); semi-rigid hose systems (EN 694). As a code
22、of practice, this British Standard takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not misleading. This publication does not purport to include all the necessary provisio
23、ns of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 83 and a back cover. The BSI cop
24、yright notice displayed in this document indicates when the document was last issued. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: London South Bank University, London South Bank Univ
25、ersity, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 BSI 29 August 2003 1 0 Introduction 0.1 General introduction Smoke and heat exhaust ventilation systems (SHEVS) create a smoke free layer above a floor by removing smoke. They can, therefore, improve conditions to
26、allow the safe escape and/or rescue of people and animals, to protect property and to permit a fire to be fought while still in its early stages. Ventilation systems for smoke removal also serve simultaneously for heat exhaust and can exhaust hot gases released by a fire in the developing stage. The
27、 use of such systems to create smoke free areas beneath a buoyant smoke layer has become widespread. Their value in assisting in the evacuation of people from buildings, reducing fire damage and financial loss by preventing smoke logging, facilitating fire-fighting, reducing roof temperatures and re
28、tarding the lateral spread of fire is firmly established. For these benefits to be realised it is crucial that smoke and heat exhaust ventilators operate fully and reliably whenever called upon to do so during their installed life. Components for a SHEVS need be installed as part of a properly desig
29、ned smoke and heat exhaust system. Natural SHEVS operate on the basis of the thermal buoyancy of the gases produced by a fire. The performance of these installations depends, for example, on: the temperature of the smoke; the fire size; the aerodynamic free area of the ventilators, or the volume of
30、smoke exhausted by powered ventilators; the wind influence; the size, geometry and location of the inlet air openings; the size, geometry and location of smoke reservoirs; the time of actuation; the arrangements and dimensions of the building. Ideally the design fire upon which calculations are base
31、d shows the physical size and heat output of the fire changing with time in a realistic manner, allowing the growing threat to occupants, property and fire-fighters to be calculated as time progresses. Such time-based calculations of the time-to-danger usually have to be compared with separate asses
32、sments of the time recommended for safe evacuation of occupants of the building or of the time recommended for initiation of successful fire-fighting. These latter assessment procedures fall outside the scope of this British Standard, although it is anticipated to supplement this standard with desig
33、n procedures for time-dependant fires in the future. In these calculations fire growth curves are selected that are appropriate to the precise circumstances of the building occupancies, fuel arrangements and sprinkler performance, where appropriate. Where such information is available, these calcula
34、tions are conducted on a case-by-case basis using recommended fire safety engineering procedures. Even where such an approach is adopted, appropriate performance recommendations, e.g. minimum clear height, external influences, can be drawn from this British Standard. NOTEBS 7974 describes the applic
35、ation of fire safety engineering principles to the design of buildings. Where such time-based calculations are not feasible, it is possible to use a simpler procedure based on the largest size a fire is reasonably likely to reach in the circumstances. This time-independent or steady-state design is
36、not to be confused with steady fires, which achieve full size instantly and then burn steadily. Rather the procedure assumes that a SHEVS that is able to cope with the largest fire can also cope with the (usually earlier) smaller stages of the fire. In practice, it is much easier to assess the large
37、st reasonably likely size of fire than to assess the growth rate of that fire. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:47:33 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7346-4:2003 2 BSI 29 August 2003 0.2 Smoke exhaust ventilation design philosophi
38、es 0.2.1 Protection of means of escape (life safety) A common approach to protect a means of escape is to achieve a smoke-free height beneath a thermally buoyant smoke layer below a ceiling. A SHEVS uses this principle to allow the continued use of escape routes that are in the same space as the fir
39、e, e.g. within enclosed shopping malls and many atria. The rate of smoke exhaust (using either natural smoke exhaust ventilators or powered smoke exhaust ventilators) is calculated to keep the smoke at a safe height above the heads of people using the escape routes, and to keep the radiated heat fro
40、m the smoke layer at a low enough value to allow the escape routes to be used freely, even while the fire is still burning. 0.2.2 Temperature control Where the height of clear air beneath the thermally buoyant smoke layer is not a critical design parameter, it is possible to use the calculation proc
41、edures in 0.2.1 in a different way. The rate of smoke exhaust can be designed to achieve (for a specified size of fire) a particular value for the temperature of the gases in the buoyant layer. This allows the use of materials that would otherwise be damaged by the hot gases. A typical example is wh
42、ere an atrium faade has glazing that is not fire-resisting, but which is known to be able to survive gas temperatures up to a specified value. The use of a temperature control SHEVS in such a case could, for example, allow the adoption of a phased evacuation strategy from higher storeys separated fr
43、om the atrium only by such glazing. 0.2.3 Assisting the fire-fighting operation In order for fire-fighters to deal successfully with a fire in a building, it is first necessary for them to drive their fire appliances to entrances that give them access to the interior of the building. They then need
44、to transport themselves and their equipment from this point to the scene of the fire. In extensive and multi-storey complex buildings this can be a long process and involve travel to upper or lower levels. Even in single-storey buildings the fire-fighters within the building need, amongst other thin
45、gs, an adequate supply of water at sufficient pressure to enable them to deal with the fire. The presence of heat and smoke can seriously hamper and delay fire-fighters efforts to effect rescues and carry out fire-fighting operations. The provision of SHEVS to assist means of escape or to protect pr
46、operty aids fire-fighting. It is possible to design a SHEVS similar to that described in 0.2.1 to provide fire-fighters with a clear air region below the buoyant smoke layer, to make it easier and quicker for them to find and to fight the fire. Temperature control designs are of less benefit. This d
47、ocument does not include any functional recommendations for key design parameters where the primary purpose of the SHEVS is to assist fire-fighting. Such functional recommendations need to be agreed by the fire service responsible for the building in question. However, the calculation procedures set
48、 out in the annexes of this document can be used to design the SHEVS to meet whatever recommendations have been agreed. 0.2.4 Property protection Smoke exhaust ventilation cannot by itself prevent fires growing larger but it does guarantee that a fire in a ventilated space has a continuing supply of
49、 oxygen to keep growing. It follows that smoke exhaust ventilation can only protect property by allowing active intervention by the fire services to be quicker and more effective. Property protection is therefore regarded as a special case of 0.2.3. Depending on the materials present, a property protection design philosophy can be based on the need to maintain the hot buoyant smo