BS 7346-4:2003
$215.11
Components for smoke and heat control systems – Functional recommendations and calculation methods for smoke and heat exhaust ventilation systems, employing steady-state design fires. Code of practice
| Published By | Publication Date | Number of Pages |
| BSI | 2003 | 90 |
This part of BS 7346 gives recommendations and guidance on functional and calculation methods for smoke and heat exhaust ventilation systems for steady-state design fires. It is intended for a variety of building types and applications, including single-storey buildings, mezzanine floors, warehouses with palletized or racked storage, shopping malls, atria and complex buildings, car parks, places of entertainment and public assembly and uncompartmented space within multi-storey buildings.
This standard does not include any functional recommendations for design parameters where the primary purpose of the SHEVS is to assist fire-fighting.
NOTE Such functional recommendations need to be agreed with the fire service responsible for the building in question. The calculation procedures set out in the annexes of this document can be used to design the SHEVS to meet whatever recommendations have been agreed.
This standard does not cover the following:
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smoke clearance, where smoke is exhausted from a building after the fire has been suppressed;
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cross-ventilation, where wind-induced or fan-induced air currents sweep smoke through and out of the building, usually as part of fire-fighting operational procedures;
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ventilation of stairwells, which usually represents a special application of smoke clearance and which does not necessarily protect the continued use of the stairwell;
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fully-involved fires.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | BRITISH STANDARD |
| 2 | Committees responsible for this British�Standard |
| 3 | Contents |
| 7 | 0 Introduction 0.1 General introduction |
| 8 | 0.2 Smoke exhaust ventilation design philosophies |
| 9 | 0.3 Applications of smoke and heat exhaust ventilation |
| 11 | 1 Scope 2 Normative references |
| 12 | 3 Terms, definitions, symbols and units 3.1 Terms and definitions 3.1.1 adhered plume 3.1.2 aerodynamic free area 3.1.3 ambient 3.1.4 atrium 3.1.5 attendance time 3.1.6 authority 3.1.7 automatic activation 3.1.8 backdraft 3.1.9 ceiling jet 3.1.10 channelling screen |
| 13 | 3.1.11 coefficient of discharge 3.1.12 convective heat flux 3.1.13 depressurization 3.1.14 design fire 3.1.15 exhaust ventilator 3.1.16 fire compartment 3.1.17 fire operational position 3.1.18 flashover 3.1.19 free plume 3.1.20 free-hanging smoke barrier 3.1.21 fuel-bed controlled fire 3.1.22 fully-involved fire |
| 14 | 3.1.23 geometric area 3.1.24 heat flux 3.1.25 heat release rate 3.1.26 manual operation 3.1.27 mass flux 3.1.28 mezzanine floor 3.1.29 natural ventilation 3.1.30 neutral pressure plane 3.1.31 powered ventilation 3.1.32 pressure differential system 3.1.33 quick response sprinkler 3.1.34 replacement air |
| 15 | 3.1.35 safety management staff 3.1.36 slot extract 3.1.37 smoke and heat control system 3.1.38 smoke and heat exhaust system 3.1.39 smoke and heat exhaust ventilation system 3.1.40 smoke and heat exhaust ventilator 3.1.41 smoke barrier 3.1.42 smoke control damper 3.1.43 smoke reservoir 3.1.44 spill edge 3.1.45 spill plume |
| 16 | 3.1.46 stagnant region 3.1.47 standard response sprinkler 3.1.48 steady-state design fire 3.1.49 stratification 3.1.50 temperature control system 3.1.51 transfer duct 3.1.52 ventilator 3.1.53 void edge screen 3.1.54 wind pressure coefficient |
| 17 | 3.2 Symbols and units |
| 20 | 4 General recommendations 4.1 Design objectives |
| 21 | 4.2 Reliability 4.3 Combined use of natural and powered ventilators |
| 22 | 4.4 Sequence of operation of devices comprising a single SHEVS 4.5 Interactions between different smoke zones in a building |
| 23 | 4.6 Sprinkler protection 4.7 Documentation |
| 24 | 4.8 Installation, maintenance and safety |
| 25 | 5 Calculation procedures 5.1 General 5.2 Design regions Figure 1 Design regions for a single-volume space |
| 26 | 5.3 Additional steps in the calculation |
| 27 | Figure 2 Design regions for a space where there is a spill plume |
| 28 | 5.4 Compatibility 6 Performance recommendations 6.1 The fire as a basis for design |
| 30 | Table 1 Default values of design fires 6.2 Plumes rising directly from the fire into a smoke reservoir |
| 31 | Table 2 Minimum clear height above escape routes 6.3 The flow of hot smoky gases out of a fire-room into an adjacent space |
| 32 | Table 3 Convective heat flux at the room opening 6.4 The flow of hot smoky gases under a canopy projecting beyond a fire-room’s window or opening |
| 33 | 6.5 The spill plume |
| 34 | Figure 3a) Adhered plume |
| 35 | Figure 3b) Free plume |
| 36 | Figure 4a) Deep balcony projection |
| 37 | Figure 4b) Shallow balcony projection 6.6 The smoke reservoir and ventilators |
| 39 | 6.7 External influences |
| 40 | 6.8 Inlet air (replacement air) |
| 42 | 6.9 Free-hanging smoke barriers |
| 43 | 6.10 Suspended ceilings |
| 44 | 6.11 Atrium depressurization |
| 45 | Figure 5 Flow resistance through openings in an atrium |
| 46 | 7 Interaction with other fire protection systems and other building systems 7.1 Sprinklers 7.2 Smoke and fire detection systems |
| 47 | Figure 6 Early (or premature) stratification of smoke |
| 48 | 7.3 Pressure differential systems 7.4 Public address and voice alarm systems 7.5 Lighting and signage |
| 49 | 7.6 Computerized control systems 7.7 Heating, ventilation and air-conditioning (HVAC) 7.8 Security systems |
| 50 | Annex A (informative) Default value heat release rates Annex B (informative) The plume rising directly from the fire into a smoke reservoir B.1 Plumes above large fires – where the clear height |
| 51 | Figure B.1 Limiting size of a cellular room |
| 52 | B.2 Plumes above large fires – temperature control designs B.3 Plumes above small fires – where the clear height is specified B.4 Plumes above small fires – temperature control designs B.5 Plumes above high storage fires B.6 Single-storey shopping malls – fire in an adjacent shop |
| 53 | Figure B.2 Smoke ventilation in a single-storey mall Annex C (informative) The flow of hot smoky gases out of a fire-room into an adjacent space C.1 Fuel-bed controlled fires |
| 54 | Figure C.1 Flow out of an opening with high balcony |
| 55 | Figure C.2 Flow out of an opening with downstand and projecting balcony |
| 56 | C.2 Assessment of flashover C.3 Fully-involved fires C.4 Slot extract |
| 57 | Annex D (informative) The flow of hot smoky gases under a soffit projecting beyond a fire-room’s opening or window… D.1 The mass and heat flows in the smoky gases D.2 The depth of channelling screens |
| 58 | Figure D.1 Smoke spreading sideways beneath a projecting canopy or balcony |
| 59 | Figure D.2 Smoke confined to a compact spill plume by channelling screens |
| 60 | D.3The depth of smoke barriers at the void edge to prevent spillage D.4 The capacity of a slot exhaust needed to prevent the passage of smoke |
| 61 | Figure D.3 Slot exhaust |
| 62 | Annex E (informative) The spill plume E.1 Entrainment into spill plumes E.2 Temperature control systems Annex F (informative) The smoke reservoir and ventilators F.1 The temperature of the smoke layer |
| 63 | F.2 Minimum depth of reservoir layer for flow toward exhaust ventilators F.3 The use of a slot exhaust instead of a boundary smoke barrier |
| 64 | F.4 The total exhaust capacity of powered smoke exhaust ventilators F.5 Total area of natural smoke exhaust ventilators |
| 65 | F.6 Minimum number of exhaust locations F.7 Smoke transfer ducts Figure F.1 Use of smoke transfer ducts in otherwise stagnant regions |
| 66 | Annex G (informative) The influence of zones of overpressure and/or zones of suction upon a SHEVS G.1 Zone of overpressure G.1.1 The zone of overpressure surrounding an outstanding structure due to wind is assessed to be the a… Figure G.1 Zones of overpressure on a roof with an outstanding structure |
| 67 | Figure G.2 G.1.2 Location of natural vents is possible in any other case provided that wind tunnel tests show that… G.2 Zones of suctions |
| 68 | Figure G.3 Zones of suctions affecting the location of inlet openings |
| 69 | Annex H (informative) Deflection of free-hanging smoke barriers H.1 A smoke barrier not reaching the floor |
| 70 | Figure H.1 Forces acting on a deflected smoke barrier |
| 71 | H.2 Barriers closing an opening |
| 72 | Figure H.2 Forces acting on a deflecting smoke barrier closing an opening |
| 73 | Annex I (informative) Plenum chamber I.1 General |
| 74 | Figure I.1 Plenum chamber I.2 Naturally ventilated plenums |
| 75 | I.3 Powered ventilated plenums Annex J (informative) Atrium depressurization J.1 Principles of depressurization J.1.1 Natural depressurization |
| 76 | Figure J.1 Neutral pressure plane – throughflow ventilation |
| 77 | Figure J.2 Neutral pressure plane – exhaust larger than inlet |
| 78 | Figure J.3 Neutral pressure plane above highest leaky storey |
| 79 | J.1.2 Natural depressurization and wind pressures |
| 80 | J.1.3 Powered depressurization |
| 81 | J.2 Depressurization combined with a SHEVS (a hybrid system) J.2.1 Mass flow-based system |
| 82 | Figure J.4 Principles of hybrid smoke ventilation system – mass flow-based |
| 83 | J.2.2 Temperature-based systems |
| 84 | Figure J.5 Principles of hybrid smoke ventilation system – temperature-based |
| 85 | Annex K (informative) The interaction of sprinklers, a SHEVS and fire-fighting actions K.1 Objectives and single systems K.1.1 Protection of means of escape (life safety) K.1.2 Property protection K.2 Objectives and combined systems K.2.1 Protection of means of escape (life safety) K.2.2 Property protection K.3 Some further considerations for combining SHEVS and sprinklers K.3.1 Local effects of the sprinkler spray on nearby natural ventilators can reduce the efficiency of t… K.3.2 Each fan intake can be regarded as equivalent to a natural ventilator for the purposes of |
| 86 | Annex L (informative) The effect of a buoyant layer on the minimum pressure recommended for a pressure di… L.1 Assessment of height of the neutral pressure plane (NPP) L.1.1 General L.1.2 With a dominant inlet |
| 87 | Figure L.1 The neutral pressure plane and layer buoyant pressure |
| 88 | L.1.3 With no dominant inlet L.2 The pressure rise at a specified height above the NPP |
| 89 | Untitled |
