Abstract: This invention provides an improved construction for air filters wherein the filter frame is provided with indentations or recesses adjacent to its opposite corners which allow a plurality of filters to nest together in a laterally offset relationship to conserve space. The invention can be employed with an air filter including a filter element of fibrous material and a frame for supporting the filter element at its marginal edges. A set of recesses is formed in the same face of the filter frame and located along adjacent sides of the frame at positions adjacent to its opposite corners. The recesses are spaced from diagonally opposite corners of the filter frame by substantially the same distance to permit a pair of filters to nest together in a laterally offset relationship for shipment or storage.

Abstract: This invention provides an improved construction for air filters wherein the filter frame is provided with indentations or recesses adjacent to its opposite corners which allow a plurality of filters to nest together in a laterally offset relationship to conserve space. The invention can be employed with an air filter including a filter element of fibrous material and a frame for supporting the filter element at its marginal edges. Preferably, a set of recesses is formed in the filter frame at positions adjacent to its diagonally opposite corners. Each recess is adapted to receive the frame of another air filter to permit the filters to nest together in a laterally offset relationship for shipment or storage. The air filters are arranged in a stack with alternate filters in the stack diagonally displaced relative to the remaining air filters. The recesses permit each air filter to be nested with one or both of its neighbors.

Abstract: An air filter panel comprising a filter element of fibrous material supported at its marginal edges by a stiff paper frame is provided. The strip of stiff paper is scored along two spaced longitudinal lines and folded away from the longitudinal lines to form a trough for receiving the filter element, the strip also being folded transversely to form a closed configuration surrounding the filter element to receive the marginal edges of the filter element in the trough. The frame is triangular in cross section with an outer wall, a flat rear wall extending inward from the outer wall toward the filter element, and an inclined front wall extending inward from the outer wall toward the filter element and sloping toward the rear wall. The front wall terminates in a flange disposed in a parallel relationship with the rear wall. The flange is secured to the rear wall with the filter element compressed therebetween to hold the frame and filter element together.