Stair pressurization systems for smoke control: design considerations.

Literature on the various types of pressurization systems, stair use during evacuation, and code requirements was reviewed and summarized. Non-fire and fire tests were conducted in the 10-story experimental fire tower of the National Fire Laboratory of the National Research Council of Canada. The flow resistances of an open stair door at various angles were measured. Under fire conditions, the vertical profiles of pressure differences across the stairshaft wall and those of the velocity pressure at the stair door opening were measured. With the stairshaft pressurized, the critical velocities required to prevent smoke backflow at the stair door opening on the fire floor were determined and compared with the calculated values for various fire temperatures.