Filter insert, for installation in room ventilation duct, has compressible seal with smooth surface at edges

摘要

On at least one narrow side (3, 7) of the folded bellows section (1) is a seal (8). This has a smooth surface, and is compressible in a direction at right angles to the plane formed by the narrow side. The seal has a high modulus of elasticity parallel to the plane. A sealing strip (4) intervenes between the bellows and the seal. It is the same width as the side and is thinner than the seal. The seal runs around all narrow sides of the filter. It is non-flammable or flammable only with difficulty. It is a closed cell foam. Seal and bellows or sealing strip, are attached by ultrasonic welding. Alternatively, an underlayer forms the sealing strip.