ABSTRACT
Most fire deaths are due to the inhalation of smoke and toxic gases. It is therefore important for the fire protection engineer to be well acquainted with the design methods used to control the flow of smoke in a building and to know how these are arrived at. In this chapter we state the conservation laws for mass and energy and apply these to a number of fire protection problems. The conservation equations are often presented as coupled differential equations that must be solved simultaneously by computer. We introduce a number of commonly applied assumptions that allow these equations to be considered separately and thus derive analytical solutions and iterative methods that can be applied to problems to do with the smoke filling process. We consider compartments under two types of ventilation conditions: closed compartments with only small leakage vents, which results in a dynamic pressure build-up, and compartments with openings large enough to prevent the buildup of pressures due to gas expansion. We apply the conservation equations to calculate smoke filling time and derive smoke-control methodologies for several cases.
