LIGHT EXTINCTION BY FIRE SMOKES

Visibility of escape routes is most important to guarantee the safety of people indoors during fires. In the case of a fire, visibility is s trongly influenced by the smoke present in the room. In the present wo rk, the extinction coefficient of the visible light has been experimen tally measured in the presence of the smoke produced by four different test fires, named TF2, TF3, TF4, and TF5. Tests have been carried out in a specially suited test room in the Italian Fire Department Resear ch Center, provided with instruments to measure the optical density of smoke and the spectral extinction coefficient. The results show that, between the smokes produced in the test fires, TF3 behaves as the mos t absorbent one, for the so-called white smokes (with a predominance o f particles of condensed liquid), and TF4 for the black smokes (with p redominantly soot particles). Results can also be used to quantitative ly calculate the light intensity reduction due to the possible fire th at could be produced in a room, in order to properly design the emerge ncy lighting system of the escape ways. Verification tests with a norm al emergency lamp have been performed to cheek this statement. A diffe rence between the computed and measured reduction of illuminance has b een discovered, and can be ascribed to a large amount of scattered Lig ht in the white smokes.