Abstract: A filter cartridge or element for separating particles from fluid flowing inwardly through the cartridge, and a process for making the same, such cartridge having a central perforated inner tubular core member with a pre-formed mat of non-woven fibrous filter material having a width substantially equal to the length of the core member and wrapped around only the core member and itself in a continuous spiral layer to form a roll of the mat. The roll mat of filter material is contained or confined by an open mesh material such as that formed by a substantially single layer of a strand of roving wound in an open criss-cross or open diamond weave pattern around only the outer periphery of the material of the rolled mat and itself so as to maintain a permanent dimensional and structural stability or integrity during subsequent handling and use.

Abstract: Conductive filter elements are made by treating nonconductive fibrous materials such as inorganic or organic fibers with resins containing finely divided carbon. The treated fibers are then fabricated into filter elements which are electrically conductive throughout. Strands of roving or yarn which are nonconductive may be joined by twisting together with strands of conductive roving or yarn to give conductivity to the finished multiple strand. Conductive filter elements are also made from extruded fibers which are filled with carbonaceous material during extrusion. These elements permit grounding of static electrical potential which would otherwise accumulate in a nonconductive element. If desired, a controlled low potential direct or alternating electrical charge can be maintained on the filter element to enhance the separation of particles of opposite charge. Particulate filter media, such as that used in filter beds, may also be treated with carbon to form an electrically conductive filter mass.