REFERENCE NOTES BS 7346 Part 4 : 2003. BS EN 12101-1/3: 2003 : The above above refenced refenced third art documents documents have been used as desi n es gn
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i e a ety roperty rotection o re re g ers Input Data ui ing ing eigh eightt pex) pex) ui ing ing eigh eightt aves aves aunc aunch) h) a cu ate an rea umber o moke ones esign moke epth prink er perating perating emperat emperature ure Fixed data Ambient temperature Absolute ambient temperature Acceleration due to gravity Density of ambient air oe c en en o n e Coefficient of ventilation Specific heat capacity of air Selected Design Fire Size Perimeter of Fire Area of Fire Entrainment Coefficient
Ventilation area and inlet area ratio Narrowest width of smoke reservoir Downstand factor Height to underside of smoke layer Mass Flow of Smoke into layer Heat release rate per sq metre of fire Convective heat flux leaving flames Heat loss to structure Convective heat flux entering smoke layer Calculated average temperature of smoke layer so u e aver averag agee emp emp o smo smo e ayer ayer Aerodynamic Area of exhaust ventilation Powered extract rate Minimum Flowing layer depth Critical exhaust rate Minimum No. of exhaust ventilators Length of smoke ventilator Ventilator Selection Min number of vents per zone Coefficient of discharge for vent Overall measured throat area of ventilation Measured throat area of vent selected Quantity of ventilators per smoke zone Overall Quantity of vents
ser nput onstant esu s
No No Yes Notes / References a
m
. .
m² v
t To g ρ
Cv c P Af Ce AvCv/AiCi W У
Y Ml qf Qf Ql ql AvCv Vl dl Mcrit N Dv N Cv Av DSV1020
Assumed 12 m Assumed 9m For large space rooms 0.34 0.190 0.337 For small space rooms 0.5 . , 0.33, . 0.25, 0..25, 0.2 0.2, . , 0.15, . 0.1 0..1 0.33 Ran e from 1, 0.5, 10 m 78 Downstand factor - 78 if none. 4.00 m BS 7346 P4 - B.2, 32.35 kg/sec BS 7346 P4 - Annex A 500.00 kW 4500 4500.0 .00 0 kW Assessment range 5 - 20% 10.00 % 4050 4050.0 .00 0 kW BS 7346 P4 - E.2 79.00 °C . K BS 7346 P4 - F.6 4.22 m² BS 7346 P4 - F.5 33.11 m³.s-¹ 1.31 m BS 7346 P4 - F.2 720.54 kg.s-¹ BS 7346 P4 - F.9 1 BS 7346 P4 - F.11 2 1 0.67 6.30 m² 3.61 m² 2 22
Column A is the solution based upon no sprinkler system interaction with the smoke. Column B is the solution based upon the average smoke layer temperature being reduced to at or below the sprinkler operating temperature
m
Formula Used
1. Mass flow of smoke into layer
MI = Ce x P x Y
.
where, Ce is entrainment coefficient P is perimeter of fire Y Height to undesirable of smoke layer 2. Convecting Heat Flux leaving Flame
Qf = Af x qf where, Af is Area of fire qf is heat release rate per sq metre of fire 3. Convecting Heat Flux Entering Smoke layer
=
x
-
eat oss
4. Calculated average temperature of smoke layer
qI = QI / (c x MI) where, c is specific heat of air 5. Absolute average temp of smoke layer
TI = qI +273 5. Poweer Extract Rate
VI = (MI x TI) / ( ρ x To) where, ρ isdensity of air To is absolute temperature of air 6. Minimum Flowing layer depth
dI = ( (MI x TI) / (Y x (qI) . x W) )
.
where, W is Narrowest width of smoke reservoir 7. Critical exhaust rate .
Mcric = [ 2.05 x ρ x (g x To x qI) x dlv x Dv ] / TI where, dlv is design smoke depth v s eng o smo e ven a or
