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.<\/p>\n
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.<\/p>\n
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.<\/p>\n
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.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 1<\/td>\n | BRITISH STANDARD <\/td>\n<\/tr>\n | ||||||
| 2<\/td>\n | Committees responsible for this British\ufffdStandard <\/td>\n<\/tr>\n | ||||||
| 3<\/td>\n | Contents <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | Introduction 0.1 General <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | 0.2 Smoke exhaust ventilation design philosophies \u2013 steady-state and time-dependent designs <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | 0.3 Objectives for time-dependent design fire SHEVS designs 0.4 <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | 0.5 Other forms of smoke ventilation 1 Scope 2 Normative references <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 3 Terms, definitions, symbols and units 3.1 Terms and definitions <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | 3.2 Symbols and units 4 General recommendations 4.1 Design <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 4.2 Reliability <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 4.3 Combined use of natural and powered ventilators <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 4.4 Sequence of operation of devices comprising a single SHEVS 4.5 Interactions between different smoke zones in a building <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | 4.6 Sprinkler protection 5 Recommended calculation procedure 5.1 Commentary <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure 1 – Effect of smoke ventilation on smoke layer depth <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | 5.2 Selection of a design fire <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure 2 – Examples of fire development curves <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | Figure 3 – Fire growth rates Table 1- Various t2 fire growths <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 5.3 Advance selection of key success\/failure criteria <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Table 2 – Minimum clear height above floor level on escape routes 5.4 Calculation procedures for time-dependent fires <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Figure 5 – Smoke transfer duct 6.7 Average buoyant layer depth in non-rectangular section smoke reservoirs Figure 6 – Effective layer depth <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | 6.8 External influences 6.9 Inlet air (replacement air) 6.10 Free-hanging smoke barriers <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure 7 – Example of excess gap caused by deflection of smoke barrier mounted adjacent\ufffdto\ufffda column 6.11 Suspended ceilings 7 Interaction with other fire protection systems and other building systems <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | 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 <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | B.4 Acceptability criteria for calculated times Annex C (informative) Plugholing C.1 Plugholing phenomenon <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Figure C.1a) – Plugholing at a supercritical ventilator opening <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Figure C.1b) – Onset of plugholing at a critical ventilator opening Figure C.1c) – Absence of plugholing at a subcritical ventilator opening <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | Figure C.2 – Qualitative examples of time-based layer deepening <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | C.2 Calculation Annex D (informative) Factors influencing the choice of time-dependent design fires <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" 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<\/b><\/p>\n |