The report gives results of a project to develop fibrous structures for air filtration which are economical and efficient, and have low pressure drop. The structure of needle punched fabrics showed excellent characteristics as filter media. Fundamental studies were carried out to investigate the effect of different needled fabric parameters on their filtration performance and mechanical properties. High efficiency levels were obtained at relatively low pressure drop, compared to woven fabrics. Fabric parameters studied were; needling intensity, fiber orientation and length, needle size and penetration, scrim material, fabric weight, and number of passages through the needling process. The pressure drop for clean filters was predicted theoretically. Based on the fundamental studies, fabrics were developed in which Cerex 1.5 oz/sq yd was used as scrim and punching was done on stages and which were found superior in many respects to commercial fabrics.

Prepared by North Carolina State University, Schools of Engineering and Textiles, Raleigh, N.C., under grant no. R801441, program element no. EHE624. Includes appendices. Includes bibliographical references (pages 118-121).