Lifecycle Testing Results of Dimple Pleat Radial Flow HEPA Filters Under Ambient and Elevated Conditions

Abstract

The Institute for Clean Energy Technology (ICET) at Mississippi State University (MSU) has developed testing capabilities for evaluating the American Society of Mechanical Engineers (ASME) Code on Nuclear Air and Gas Treatment (AG-1) section FK radial flow HEPA filters. These high efficiency particulate air (HEPA) filters are typically used at sites within the DOE complex to control particulate matter emissions. The goal of this testing was to provide information related to the performance of radial flow HEPA filters that use dimple pleat separators. Prior to this testing, insufficient data were available to determine the lifecycle performance of these filters. Two different types of dimple pleated radial flow HEPA filters were tested: a safe change design and a remote change design. Filters were tested at both ambient and elevated conditions of temperature and relative humidity. The challenge aerosols were Alumina (Al(OH) 3 ), Carbon black, and Arizona road dust. The performance of these filters at ambient conditions was determined by the filters' mass loading capacity and filtering efficiency. Elevated condition performance was evaluated by the filters' resistance to elevated temperature and relative humidity. The results indicated that the challenge aerosol had a large impact on the total loading capacity of the filters. Testing at elevated conditions of temperature and relative humidity revealed an issue with the strength of the dimple pleats. The dimples softened when challenged with elevated conditions, which led to filter failure due to a cascading reduction in free flow area and increase in differential pressure.