Patent ID: 8157891

Claim:
A method for making a cross-pleated cartridge comprising a plurality of membrane layers, the method comprising: (a) positioning two strips of membrane, extending in substantially opposite directions, so that a portion of an edge of one membrane strip is adjacent to a portion of an edge of the other membrane strip, forming a first seam; (b) joining the adjacent edge portions of the membrane strips along the first seam to form a membrane layer; (c) making a 45° fold in each membrane strip towards and then overlaying the first seam, to form a second seam at 90° to the first seam; (d) joining the adjacent edge portions of the membrane strips along the second seam to form another membrane layer; (e) making a 45° fold in each membrane strip towards and then overlaying the second seam, to form another first seam at 90° to the second seam; (f) repeating steps (b) to (e), thereby forming the cross-pleated cartridge with a stacked array of passageways between the membrane layers.