BS 7346-5:2005
$167.15
Components for smoke and heat control systems – Functional recommendations and calculation methods for smoke and heat exhaust ventilation systems, employing time-dependent design fires. Code of practice
| Published By | Publication Date | Number of Pages |
| BSI | 2005 | 42 |
This British Standard gives functional recommendations and guidance on the calculation method for smoke and heat exhaust ventilation systems (SHEVS) for time-dependent design fires. A variety of building types is addressed.
For a pre-determined critical time, this British Standard can be used to determine required performance of a SHEVS needed to avoid the onset of a significant danger. Or, for a pre-determined SHEVS, this British Standard can be used to determine the time available between ignition and onset of significant danger.
This British Standard uses accepted and authoritative methods to define some design parameters, e.g. the time needed for safe evacuation or attendance time of the fire-fighting services. This information can be sought from other sources when generating the overall fire-safety concept for a specific building project.
Many of the detailed calculation procedures, and most of the danger criteria defining the boundary between success and failure, are the same for time-dependent design fires as for steady-state design fires, and it is essential that this British Standard be used in conjunction with BS 7346-4.
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | BRITISH STANDARD |
| 2 | Committees responsible for this British�Standard |
| 3 | Contents |
| 5 | Introduction 0.1 General |
| 6 | 0.2 Smoke exhaust ventilation design philosophies – steady-state and time-dependent designs |
| 7 | 0.3 Objectives for time-dependent design fire SHEVS designs 0.4 |
| 8 | 0.5 Other forms of smoke ventilation 1 Scope 2 Normative references |
| 9 | 3 Terms, definitions, symbols and units 3.1 Terms and definitions |
| 14 | 3.2 Symbols and units 4 General recommendations 4.1 Design |
| 16 | 4.2 Reliability |
| 17 | 4.3 Combined use of natural and powered ventilators |
| 18 | 4.4 Sequence of operation of devices comprising a single SHEVS 4.5 Interactions between different smoke zones in a building |
| 19 | 4.6 Sprinkler protection 5 Recommended calculation procedure 5.1 Commentary |
| 20 | Figure 1 – Effect of smoke ventilation on smoke layer depth |
| 21 | 5.2 Selection of a design fire |
| 22 | Figure 2 – Examples of fire development curves |
| 23 | Figure 3 – Fire growth rates Table 1- Various t2 fire growths |
| 24 | 5.3 Advance selection of key success/failure criteria |
| 25 | Table 2 – Minimum clear height above floor level on escape routes 5.4 Calculation procedures for time-dependent fires |
| 26 | 6 Further acceptability criteria 6.1 General 6.2 Confirmation that layer depth selected is greater than minimum possible 6.3 Depth margin for smoke reservoir boundary smoke barriers |
| 27 | Figure 4 – Smoke barrier depth margin (with barrier in deflected position) 6.4 Slot extracts used to define a smoke reservoir boundary 6.5 Avoidance of natural and powered smoke exhaust ventilators in the same smoke reservoir 6.6 Smoke transfer ducts |
| 28 | Figure 5 – Smoke transfer duct 6.7 Average buoyant layer depth in non-rectangular section smoke reservoirs Figure 6 – Effective layer depth |
| 29 | 6.8 External influences 6.9 Inlet air (replacement air) 6.10 Free-hanging smoke barriers |
| 30 | Figure 7 – Example of excess gap caused by deflection of smoke barrier mounted adjacent�to�a column 6.11 Suspended ceilings 7 Interaction with other fire protection systems and other building systems |
| 32 | Annex A (normative) Supporting documentation Annex B (informative) Example of an iterative calculation procedure B.1 Design fire curve B.2 Time B.3 Time to onset of danger |
| 34 | B.4 Acceptability criteria for calculated times Annex C (informative) Plugholing C.1 Plugholing phenomenon |
| 35 | Figure C.1a) – Plugholing at a supercritical ventilator opening |
| 36 | Figure C.1b) – Onset of plugholing at a critical ventilator opening Figure C.1c) – Absence of plugholing at a subcritical ventilator opening |
| 37 | Figure C.2 – Qualitative examples of time-based layer deepening |
| 38 | C.2 Calculation Annex D (informative) Factors influencing the choice of time-dependent design fires |
| 40 | Bibliography |
