Recirculating Ventilation System in an Integrated Maintenance Hangar Supporting B-1B and KC-135 Aircraft

摘要

During 1998 the Corps of Engineers (CoE) built an integrated maintenance hangar (Building 198) to support maintenance of B-1B and KC-135 aircraft at Mountain Home Air Force Base (MHAFB). Recirculation of 80% of the exhaust air was included in the design as an energy conservation measure, and carbon adsorption was applied to the exhaust stream to capture VOCs. Routine Industrial Hygiene exposure sampling for chromate and for isocyanates was conducted by MHAFB staff during application of prime and top coats, respectively, and all measurements were below the respective method detection limits. However, although the CoE design delivered provided strong air movement in most areas inside the hangar, the ventilation field included many regions of intense turbulence, in which the application of paint is difficult. Some amelioration of turbulence was accomplished by adjustment of baffles and vents at the exits from the ventilation ducts, and the hangar is now in routine use, setting a concrete precedent for operating in Recirculating ventilation mode under the de minimis 'violation' defined by OSHA and applied to 29 CFR 1910.107 (d) (9). MHAFB is planning an eventual hangar modification project to relocate the ventilation intakes and exhaust, to even out the airflow pattern.