On the use of time constants for specifying the smoke filling process in atrium halls

The time constant proposed to specify the smoke filling time in an atrium hall for design purposes is further evaluated in this paper using the plume expression fitted by dimensional analysis. The zone model FIRST developed at the Building and Fire Research Laboratory, NIST, U.S.A. is used to simulate the smoke filling time. Predicted results of the zone modelling simulation supported the fact that the time required to fill 80% of the atrium space with smoke is related to its time constant. Full-scale experimental results on smoke filling processes in atria available in the literature are used to justify this parameter. Use of this quantity to specify the smoke filling time for an atrium space is recommended with a selected design fire.