A filter for purifying air includes a frame, layers of a filter medium, and separator plates. The layers of the filter medium and the separator plates are arranged in the frame. The layers of the filter medium are aligned at a distance from each other and one of the separator plates is arranged between each two layers of the filter medium. The separator plates are folded and are provided with folding in such a way that the separator plate is designed with a number of fold peaks and fold valleys on its first side and a multiple number of fold peaks and fold valleys on its other, second side. The fold peaks and fold valleys extend from the first side to the second side. The folding, as viewed in the flow direction, causes a trapezoidal cross-section of a respective separator plate.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

A filter element has a zigzag-folded filter medium. Filter medium sections joined by a fold edge define an intermediate fold space, respectively, with a fold base and fold peaks opposite the fold base. An elongate support section is arranged in the intermediate fold space on a filter medium surface of one of the filter medium sections. The support section extends perpendicular to the fold edges between fold base and fold peak. The support section has a height extension perpendicular to the filter medium surface that increases in longitudinal direction of the support section from fold base to fold peak. The support section has a free side facing away from the filter medium surface. The support section has a width extension parallel to the fold edges. The width extension decreases parallel to the filter medium surface and perpendicular to the longitudinal direction from fold peak to fold base.

Support and drainage materials, filter including the materials, and methods of use are disclosed.

Disclosed are improved polymer materials. Also disclosed are fine fiber materials that can be made from the improved polymeric materials in the form of microfiber and nanofiber structures. The microfiber and nanofiber structures can be used in a variety of useful applications including the formation of filter materials.