Abstract: A filter assembly includes a reusable filter frame and a replaceable, pleated, reversibly expandable, self-spacing filter removably arranged in the frame. The self-spacing pleated filter expands uniformly with equal pleat spacing to allow the filter to be easily installed in the reusable filter frame without the aid of a secondary spacing structure. When the filter is expanded to the length of the filter frame, the filter is under tension, thereby allowing the length of the filter to be readily adjusted to match the length of the frame and allowing the pleats to be aligned with corresponding ribs provided in the frame.

Abstract: A replaceable, self-spacing, pleated, filter insert that can be easily installed in a reusable filter frame without the aid of a secondary spacing structure includes reversibly collapsible and expandable filter media including a plurality of pleats that expand uniformly when the filter is expanded. When the filter is expanded to the length of the filter frame, the filter is under tension and behaves like a spring, thereby allowing the length of the filter to be readily adjusted to match the length of the frame and allowing the pleats to be aligned with corresponding ribs provided in the frame.

Abstract: A reusable filter frame adapted to receive a replaceable filter element includes a base and a cover connected with the base. The base includes a plurality of longitudinal rails and a plurality of transverse ribs for supporting and spacing the filter element. The filter frame also includes a securing mechanism for securing the filter element to the frame and maintaining the filter element in its expanded condition.

Abstract: A filter assembly includes a reusable filter frame and a collapsible and expandable filter element. The filter frame includes a base and a cover connected with the base. The base includes a plurality of longitudinal rails and a plurality of transverse ribs for supporting and spacing the filter element. The filter frame also includes a securing mechanism for securing the filter element to the frame and maintaining the filter element in its expanded condition. The filter element includes filter media having a plurality of pleats adapted to mesh with the ribs of the filter frame and a flexible spacing structure attached to the pleated media that provides the pleated media with uniform pleat spacing but allows the media to be collapsed to a compact form.

Abstract: A filter assembly with a frame and a filter element including a sheet of filter media with attachment strips at opposite ends. The frame positions the filter element with the filter media across a passageway in the frame and with the attachment strips along opposite end parts of a perimeter portion of the frame. Abutments extend along the perimeter portion between its end parts and along opposite edges of the filter material. Projections on the end parts are engaged in openings in the attachment strips and are spaced from the abutments such that the filter element can be mounted on the frame with either of the attachment strips engaged with the projections at either of the end parts while the filter element can only be mounted on the frame with an inlet surface of the sheet of filter material facing the same direction as a front surface of the frame.

Abstract: A filter assembly including a frame having a through passageway between front and rear surfaces surrounded by a perimeter portion; and a filter element including a sheet of flexible filter media with longitudinal attachment strips at opposite ends and extending at about a right angle to opposite edges of the sheet. Structure on the frame receives and positions the filter element with the sheet of filter media extending across the passageway with an inlet surface of the sheet facing the same direction as the front surface of the frame and with the attachment strips of the filter element extending along opposite end parts of the perimeter portion.

Abstract: A reversibly expandable filter element includes pleated filter media and a flexible spacing structure attached to the pleated media that provides the pleated media with uniform pleat spacing.

Abstract: A reversibly expandable filter element includes pleated filter media and a flexible spacing structure attached to the pleated media that provides the pleated media with uniform pleat spacing.

Abstract: A reusable filter frame adapted to receive a replaceable filter element includes a base and a cover connected with the base. The base includes a plurality of longitudinal rails and a plurality of transverse ribs for supporting and spacing the filter element. The filter frame also includes means for securing the filter element to the frame and maintaining the filter element in its expanded condition.

Abstract: A filter assembly includes a reusable filter frame and a collapsible and expandable filter element. The filter frame includes a base and a cover connected with the base. The base includes a plurality of longitudinal rails and a plurality of transverse ribs for supporting and spacing the filter element. The filter frame also includes means for securing the filter element to the frame and maintaining the filter element in its expanded condition. The filter element includes filter media having a plurality of pleats adapted to mesh with the ribs of the filter frame and a flexible spacing structure attached to the pleated media that provides the pleated media with uniform pleat spacing but allows the media to be collapsed to a compact form.

Abstract: Disclosed is a change indicator for a filter for use in a gaseous circulation system, such as a forced air heating and cooling system. The change indicator includes an air impervious patch that is secured to the filter. The portion of the filter media adjacent to the change indicator changes appearance in response to the accumulation of contaminants at a much slower rate than the remainder of the air filter. The accumulation of contaminants progresses inwardly from the region adjacent the periphery of the change indicator towards the region adjacent to the center. Once the appearance of the filter media beneath the change indicator fully changes from periphery to the center, that is an indication that the air filter is in need of cleaning or replacement.