Fire Safety Science Digital Archive

Emergency exit signs and lights are significant for effective evacuation in case of emergency. However visibility of those signs drops drastically in case of fire because of fire smoke. As reported in the Daegue subway train fire in Korea, lost of visibility causes serious problems for safety evacuation. A series of experiments is conducted to examine the visibility of various kinds of emergency exit signs and lights through fire smoke. Relations between visibility described by visible distance (V(m)) and optical smoke density (Cs(1/m)) are obtained quantitatively as expressed by V=k1/Cs+k2, where ki is experimental constant for each emergency signs and lights. Also improvement of the visibility by increasing luminous intensity is examined.