ABSTRACT
The detailed analysis of an emission/exposure problem is an important phase of exhaust ventilation design. The temptation may be to design a large hood covering the entire machine, or to provide a large volume of general ventilation to the area, or to design a partial enclosure with exhaust. While any of these might be justified as the final design, they cannot be justified until all the particular sources have been located, the pulvation mechanism understood, and an attempt made to rate the several sources according to their probable relative contribution to the overall contamination. With these data, the feasibility of designing local exhaust hoods can be appraised. One simple tool in the observation of dusty processes is some form of Tyndall beam illumination. The escape of occasional wisps of air at points most remote from exhaust openings is not necessarily to be construed to indicate unsatisfactory operation of the exhaust hood.
