A Short Note on Using a Time Constant in Specifying Smoke Filling Time in an Atrium Under an Unsteady Fire

A time constant derived from a t-squared fire with the geometry of an atrium is proposed to specify the smoke filling time. The smoke filling pro cesses in 27 atria with volume varying from 2,500 to 35,000 m3were simulated by the fire zone model CFAST version 2.0. The atria are located adjacent to a “fire” shop at a lower level. Correlation relationships between the smoke filling time and the time constant are derived. Further, performance of smoke control systems in the atria are evaluated.