Patent ID: 8226786

Claim:
A method of preparing a filter construction for use in an air cleaner; the method comprising steps of: (a) providing a filter media construction comprising a fluted filter media sheet secured to a facing sheet of filter media with a first seal therebetween against a first side of the facing sheet; (b) forming a generally circular coiled configuration by coiling the filter media combination at least 10 times around with the facing sheet directed to the outside of the coiled configuration and with a sealant strip, during the coiling, positioned between the fluted filter media sheet and a second side of the facing sheet; (i) the step of forming a coiled configuration comprising providing a resulting generally circular coiled configuration in the form a coreless coil having: a central open space; and, an outside perimeter of at least 60 cm; (c) distorting the generally circular coiled configuration having a central aperture to a media construction having a shape with two generally parallel sides joined at their ends by curved portions; (i) the step of distorting including closing the central open space with sealing of the fluted filter media to itself, by a sealant, to provide a media construction having a shape with no center core; and, (ii) the step of distorting comprising forming an inner sealant strip in a center of the resulting media construction that is at least 12 cm long; and, (d) positioning a housing seal on the media construction.