Abstract
A new form of dust control has been devised for portable grinders. The method has been developed on a study of the aerodynamics of the system, as shown by cine-photographs of the moving dust clouds produced when grinding. It was known from earlier work that the dust of respirable size range did not follow the sparks thrown off by a grinding wheel. In consequence, the present work, which represents the first attempt to control dust through the portable wheel-guard, was directed to the control of dust of the respirable size range. Still photographs of the dust clouds are included in the paper.
For many years pneumatic chisels have been used without any method of dust control, although an increasing volume of medical evidence has shown that these tools produce dangerous dust in certain industries. In some cases stone masons have fitted small local exhaust ventilation hoods in front of the chisel, and a recent paper described an exhausted dressing bench for use in steel foundries. There are, however, many instances where the work cannot easily be placed on such a bench, and so a new dust-control system has been fitted to a pneumatic chisel. In this design local exhaust ventilation is applied through a hollow chisel, and the dust is extracted through the pneumatic hammer.
The main effort has been directed to the control of dust within the respirable size range, and the whole system was evolved as a result of the observation of the paths taken by the airborne dust produced by chipping. The moving dust clouds observed during the development stages have been photographed by a cine-camera, and the paper includes still photographs taken from the 35-mm. film negative.
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