The subway train and station fire in Daegue, Korea, on 18 February, 2003, revealed significant hazard in case of a fire in underground railway systems. Few experiments or modeling works have been conducted on smoke movement, fire growth and human behavior in underground railway train stations, although the rather low ceiling of stations and high fire load in train and the connection of a station to a tunnel are thought to be disadvantageous for the restriction of fire spread or the effective smoke control. Smoke movement tests were conducted using simulated fire sources on the platform in three subway stations currently in service in Tokyo in October 2003. The tests were conducted at midnight to avoid conflicts with the traffic services. Operation of smoke extraction system and the fire shutters in the stairway connected the platfrom and the concourse was the major experimental parameters. Distribution of temperature, velocity and static pressure throughout the platforms, the tunnel, and concourse were measured. This paper reports the experimental results of only Center platform stations. From the test results, following summaries can be drawn on the general characteristics in the smoke movement and the smoke control performance in the subway station. Operation of fire shutters in the stairway has primary influence on the smoke movement. Closure of the shutters is generally beneficial not only for saving the concourse from smoke but also for keeping smoke layer on the platform level stable. Smoke movement and effectiveness of smoke control can be notably affected by the background air flow through the tunnel and outlets of the subway station.
Expandable graphite begins to expand at the elevated temperature of around 150 to 300 °C without flaming combustion even at ca.900 °C. This paper reviews recent research and development of halogen-free flame-retardant polymeric materials which contain expandable graphite, focusing particularly on its utilization as a flame retardant for polyurethane rubber and polyolefin materials. This literature survey has revealed that some polymeric materials which contain expandable graphite may increase the limiting oxygen index, and decrease the peak rate of heat release in the cone calorimeter test, effectively. In addition, synergetic flame-retardant effect of expandable graphite on some phosphorus-containing flame retardants, magnesium hydroxide, etc, has also been reviewed.