Controlling Smoke Movement; Basic Concept - Simplex 4100U Application Manual

Controlling Smoke Movement

Basic Concept

Second Floor
First Floor
Regardless of the method, the basic concept behind controlling smoke is to use differences in air
pressure to minimize the spread of smoke and, if possible, vent it from the building.
You cannot confine smoke by simply closing all access ways (such as doors and vents) to the
room that has the fire in it. Even with these passages closed off, smoke can disperse throughout a
building via cracks, holes made for pipes and electrical wires, and spaces around doors and
windows. Smoke is driven through these small openings by the expanding gases from the fire.
Smoke can also be driven onto other floors by the "stack effect," which causes air to rise in
buildings. The stack effect is caused by the difference in the interior and exterior temperature of
the building. The figure below shows how smoke can disperse throughout a building:
Adjacent Room
Adjacent Room
Figure 1-1. Smoke Infiltrating Rooms Adjacent to the Fire
Adjacent Room
SMOKE
Area On Fire
1-3
Adjacent Room
Adjacent Room
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