By Clyde J. Porter, Wyman Gordon Company, N. Grafton, MA

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A worker in the process grinding area

Controlling worker exposure to dusts and fumes is a major concern at Wyman Gordon, a division of Precision Castparts Corporation, and a leading manufacturer of metal forgings for the aerospace and industrial gas turbine industries. In the Process Grinding Department at one plant, for example, sidedraft exhaust benches are used to limit exposure to metal grinding dust. Airpak was recently used to compare the capture efficiency of these benches with other types of exhaust systems in order to determine the best approach to minimize the amount of dust in the worker's breathing zone.

Four different hood configurations were modeled during the project, along with various combinations of exhaust and supply airflow rates. These included the existing side-draft hood, and modifications to it, as well as three booth-type hoods, one with an open roof, the others with a partial and a full roof.

The final selected design was a modification of the existing hood that demonstrated the best combination of performance improvement and feasibility. Making use of existing fans and filters, the new design will cut worker dust exposure by up to 50%. Because the existing equipment could be utilized, construction cost savings of $250,000 for 10 workstations could be realized. Without Airpak, it would have cost at least $25,000 and up to a year of additional work to develop and test prototype hoods. As an added benefit, plant management has found Airpak model output very helpful in understanding why various project options were selected.

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