Spiral-wound membrane cartridge

A reverse osmosis or ultrafiltration separation device for treating a liquid feed which comprises

• a porous central tube for carrying permeate,
• at least one separation assembly wound in spiral relationship about said central tube, said assembly including
• an elongated envelope made of semipermeable membrane material which includes a central permeate passageway interior of said envelope and
• feed-passageway-providing sheet material spirally wound with said envelope to supply a liquid feed to be treated to the exterior surfaces of said envelope, a portion of which feed permeates through said membrane envelope into said central passageway,
• said central passageway being in communication with the interior of said central tube,
• a housing having a cylindrical chamber of circular cross section for holding said spiral wound separation assembly, having an inlet for the supply of feed to be treated, having an outlet for exit of the portion of the feed which does not permeate through said semipermeable membrane and having an exit for the permeate which collects in said central tube, and
• a seamless, highly porous, substantially rigid, tubular sleeve tightly surrounding said spirally wound separation assembly, said sleeve being proportioned so that said sleeve and said surrounded spirally wound separation assembly is snugly received within said cylindrical chamber,
• said sleeve having a predetermined thickness relative to the diameter of said chamber so that desired bypass flow of feed liquid will occur in the space occupied by said sleeve.