Development of a light sensing self-adjusting hood for welding fumes.

Recently, the incidence of pneumoconiosis due to inhalation of welding fumes has become increasingly remarkable in Japan. Although several engineering methods such as local exhaust ventilation, push-pull ventilation and general (dilution) ventilation have been preferred for controlling airborne contaminants released from welding work, thorough reduction of the welder’s exposure to welding fumes is practically difficult in most cases because the working area for common welding work is relatively large and a lot of fumes are released from a moving source. In general, local exhaust ventilation is the most effective and economical approach to engineering control since it captures airborne contaminants very close to their source by minimum suction before dispersal of the contaminants. Nevertheless, conventional local exhaust ventilation is not effective for moving contaminant sources because an ordinary local exhaust hood is not flexible in use and cannot achieve its best performance unless it is located constantly close to the contaminant source. In this study, the author presented a light sensing selfadjusting hood for capturing welding fumes (Patent Applied for), and carried out a performance test. This self-adjusting hood was devised so as to be moved and adjust its position automatically according to the welding arc movement. Owing to the self-adjusting function, a contaminant source (arc point) is constantly positioned within the suction coverage of the hood.