A filter element including a first filter media pack with an inlet face and an outlet face and a second filter media pack with an inlet face and an outlet face. The second filter media pack is formed separately from the first filter media pack and is coupled to the first filter media pack such that the respective inlet faces and outlet faces of the first and second media packs do not overlap. The first filter media pack and the second filter media pack each include a corresponding filter media pack characteristic, and the filter media pack characteristic of the first filter media pack is different from the corresponding filter media pack characteristic of the second filter media pack. Exemplary filter media pack characteristics include the length, width, height, shape, media density, layer spacing, pleat bend angle, pleat density, and material composition of the first and second filter media packs.

The present invention relates to a filter assembly comprising at least one media pack arranged in a frame structure in which the at least one media packs is pleated and having opposing first and second open ends, and a corresponding method for manufacturing such a filter assembly for removing particles from an air stream. The method for manufacturing a filter assembly for removing particles from an air stream said comprises for each media pack sealing the first and second open ends in a first molding step, thereby providing a sealed first edge and a sealed second edge of each respective media pack, and subsequently arranging the at least one media pack in the frame structure and in a second molding step securing and sealing the sealed first edge and the sealed second edge, respectively, to at least one frame element of the frame structure.

Fluid filtration devices and methods of filtering fluids are described. The devices generally include a housing, a hollow filter assembly, a rotating cleaning assembly and a device to measure the accumulation of solids in the filter housing. In some embodiments the accumulation of solids is measured by measuring the torque required to rotate the cleaning assembly. Torque may be measured directly, such as with a torque sensor, or indirectly, such as by measuring the current used by an electric motor to drive rotation of the cleaning assembly. In some embodiments a purge valve is opened to remove accumulated solids from the housing when a certain level of solids accumulation is detected.