Study on Smoke Optical Characteristics Under Static and Dynamic Smoke-Generation Conditions

Smoke produced during a fire causes optical extinction through light scattering and absorption, reducing visibility. The optical properties of smoke can vary depending on the smoke generation environment, such as accumulation and exhaust flow conditions. Quantitative evaluation of optical properties under different conditions is necessary to ensure reliable visibility prediction. In this study, changes in the extinction coefficient were compared to analyze the effects of smoke generation environments on the optical properties of smoke. Two representative small-scale experimental apparatuses were used: an ISO 5659-2-based smoke density chamber under static conditions and an ISO/TS 5660-4-based cone calorimeter under dynamic conditions. Under static conditions, optical extinction caused by smoke accumulation continued even after the extinction coefficient reached its maximum value. In contrast, under dynamic conditions, the extinction coefficient showed two peak values during combustion progression. These results suggest that evaluating fire hazards using only optical properties derived under dynamic conditions may introduce uncertainty.