Tubular filter elements with improved side seam seal

Claim 2

A tubular corrugated filter element (F, 20) comprising at least one layer of filter sheet material (1, 2, 21) formed in a substantially tubular shape (4, 24) and having the side seam edges (7, 8, 27, 28) of the filter sheet (1, 2, 21) in adjacent relation and joined together in a side seam seal by way of a self-supporting channel strip (11, 31) characterized in that the channel strip (11, 31) is a bonding channel strip of thermoplastic resinous material, embracing said edges of the filter sheet (1, 2, 21), the channel strip (11, 31) being bonded to the filter sheet (1, 2, 21), thereby sealing said edges (7, 8, 27, 28) of the sheet (1, 2, 21) together in a leaktight seal, and blocking the escape of unfiltered liquid between the seamed edges (7, 8, 27, 28) of the filter sheet (1, 2, 21) of the tubular filter element (F, 20).

Claim 3

A tubular filter element according to claim 1 having end caps (38, 39) closing off the ends of the tubular filter element (F, 20) and bonded to the ends in a leak-tight seal.

Claim 4

A tubular filter element according to claim 2 in which the bonding channel strip (11, 31) in the side seam seal (7, 8, 27, 28) is of the same thermoplastic resinous material as the end caps (38, 39) and filter sheet (1, 2, 21), and the bonding strip material is integrated with the end caps and the filter sheet material in the side seam seal, forming an integral one-piece filter element.

Claim 5

A tubular filter element according to claim 2 wherein the end caps (38, 39) are bonded to the ends of the tubular element (F, 20) by a synthetic resin which impregnates the filter sheet material (1,2,21) at such ends.

Claim 6

A tubular corrugated filter element (F) comprising two layers of filter sheet material (1, 2) formed in a substantially tubular shape (4) and having the side seam edges (7, 8) of the filte- sheet (1, 2) in adjacent relation and joined together in a side seam seal by way of a self-supporting channel strip (11) characterized in that the channel strip is a bonding channel strip (11) of the thermoplastic resinous material and the inner surface (13) of the side seam edge (8) of the outer filter sheet (1) and outer surface (10) of the side seam edge (7) of the inner filter sheet (2) are in adjacent relation, and joined together in the side seam seal by way of the self-supporting bonding channel strip (11) which is interposed therebetween and embraces said outer edges (7) of the inner filter sheet (2), the channel strip (11) being bonded to the inner and outer filter sheets (1, 2), thereby sealing said edges (7, 8) of the two sheets (1, 2) together in a leak-tight seal, and blocking the escape of unfiltered liquid between the said edges (7, 8) of the inner and outer filter sheets (1, 2) of the tubular filter element (F).

Claim 7

A tubular corrugated filter element (F) comprising two layers of filter sheet material (1, 2) formed in a substantially tubular shape (4) and having the side seam edges (7, 8) of the filte- sheet (1, 2) in adjacent relation and joined together in a side seam seal by way of a self-supporting channel strip (11) characterized in that the channel strip is a bonding channel strip (11) of the thermoplastic resinous material and the inner surface (13) of the side seam edge (8) of the outer filter sheet (1) and outer surface (10) of the side seam edge (7) of the inner filter sheet (2) are in adjacent relation, and joined together in the side seam seal by way of the self-supporting bonding channel strip (11) which is interposed therebetween and embraces said outer edges (7) of the inner filter sheet (2), the channel strip (11) being bonded to the inner and outer filter sheets (1, 2), thereby sealing said edges (7, 8) of the two sheets (1, 2) together in a leak-tight seal, and blocking the escape of unfiltered liquid between the said edges (7, 8) of the inner and outer filter sheets (1, 2) of the tubular filter element (F).

Claim 8

A tubular filter element according to claim 5 having end caps (38, 39) closing off the ends of the tubular element (4), and bonded to the ends in a leak-tight seal.

Claim 9

A tubular filter element according to claim 6 in which the bonding channel strip (11) in the side seal is of the same thermoplastic resinous material as the end caps (38, 39), and the bonding strip material is integrated with the end caps in the side seam seal, forming an integral one-piece filter element (F).

Claim 10

A tubular filter element according to claim 6 in which the bonding channel strip (11) in the side seam seal is of the same thermoplastic resinous material as the filter sheets (1, 2), and the bonding strip material is integrated with the filter sheets in the side seam seal, forming an integral one-piece filter element (F).

Claim 11

A tubular filter element according to claim 6 wherein the end caps (38, 39) are bonded to the ends of the tubular element (4) by a synthetic resin which impregnates the filter sheet material (1, 2) at such ends.

Claim 12

A tubular filter element according to claim 5 in which the bonding channel strip (11) has penetrated at least slightly into the pores of the abutting filter sheets (1, 2) in the side seam seal.