| WHY PRESSURISATION |
| |
| Objective Of Smoke Control |
| The objective of smoke control system is to keep the smoke
and toxic gases out of escapes routes.AN adequate smoke control
system will help the fire ffighters deal both with the fire
and any residue smoke |
| |
| Smoke Ventilations |
In large open spaced buildings,car parks,shopping centers,exhibitions
halls etc. usual method of smoke control is by ventilation
,extracting the smoke from areas. |
| |
| Pressurations |
| It is possible to hold back smoke by simply supplying clean
air into the escape routes,thereby developing excess or positive
pressure in the spaces requirinng protection. |
| |
| Air Requirements |
Having established the pressure level required to hold
back the smoke ,the air volume to be supplied to escape
route to develop this pressure can be calculated by the
formula |
| Q=0.827*Ae*P**(1/n) |
| Q=the volume of air required (m3/sec) |
| Ae=Leakage area from space (m2) |
| P=Pressure differantial (Pa) |
| n=Leakage factor |
| n ; for large leakage areas doors n=2 for small leakage
areas windows cracks n=1.6 |
| |
Type of Door |
Size |
Crack Length |
Leakage Area |
|
m*m |
m |
m2 |
|
|
|
|
| Single leaf in frame opening into pressurised space |
2m*0.8m |
5.6 m |
0.01 |
| |
|
|
|
| Single leaf in frame opening into outwards |
2m*0.8m |
5.6 m |
0.02 |
| |
|
|
|
| Double leaf with or without central rebate |
2m*1.6 m |
9.2 m |
0.03 |
| |
|
|
|
| Lift Door |
2m*2 m |
8.0 |
0.06 |
|
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