scope:

The National Research Council of Canada (NRC) conducted full-scale fire experiments to investigate whether pressurecompensatingsystems areneededto maintain tenable conditions within pressurized stairwells. Ten tests were conducted in the NRC 10-story test facility with the stairwell in the facility pressurized. The tests were conducted with the stairwell door on the fire floor closed and selected stairwell doors on the other floors open. Two fire scenarios with a shielded sprinklered fire and a nonsprinklered fire were tested with varying number and location of open stairwell doors.

Tenability analyses were conducted with experimental test results to investigate the performance of the pressurized stairwell with and without pressure compensating systems. Without compensating for pressure losses, the pressure difference across the stairwell door on the fire floor decreased considerably with open stairwell doors. However, a noncompensated stairwell remained tenable for 30 minutes as long as the door on the fire floor was closed both for the shielded sprinklered fireandthe nonsprinklered fire scenarios. It is concluded that if the base pressurization system meets the requirement of the design pressure difference with a proper arrangement of air injection points, the stairwell will remain tenable as long as the door on the fire floor is closed for both sprinklered and nonsprinkled fire scenarios used in the tests