Fire Safety Science Digital Archive

In designing a mechanical smoke control system to protect escape routes, it is necessary to have information on the adverse pressure differences caused by the various mechanisms and on the level of mechanical pressurization needed t o overcome them. This paper deals with pressure differences caused by both the buoyancy force and thermal expansion due to fire. The tests were conducted in the ten-storey experimental fire tower in conjunction with a project on smoke control technology for a fire safe elevator. The calculated values of adverse pressure differences across the elevator shaft walls caused by the buoyancy force agreed well with the measured values, for fire temperatures from 450 to 850°C. Also, the minimum amounts of mechanical pressurization required for neutralization were equal to the adverse pressures caused by the buoyancy force. Those caused by thermal expansion due to the rapid temperature rise were determined with the outside wall vents closed and with them opened. The test results verified that adverse pressures caused by fire can be controlled by mechanical pressurization to prevent smoke contamination of protected spaces. The mechanical pressurization system should be operated as soon as possible as the purging time f o r a contaminated elevator shaft or lobby can be long.