US5290446A — Helical wrapped filter element

Claim 1

Independent Claim 79 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least one filter medium sheet comprising a fibrous mass of nonwoven microfibers capable of removing particulates from a fluid helically wrapped around a pervious, hollow tube to form an overlap of about 0% to about 95% of the width of said filter medium sheet and at least one diffusion layer which allows for lateral flow of said fluid within said fluid treatment element.

Claim 2

Dependent Claim 79 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least one filter medium sheet comprising a fibrous mass of nonwoven microfibers capable of removing particulates from a fluid helically wrapped around a pervious, hollow tube to form an overlap of about 0% to about 95% of the width of said filter medium sheet and at least one diffusion layer which allows for lateral flow of said fluid within said fluid treatment element.

Claim 3

Dependent Claim 31 words

The fluid treatment element of claim 1, which element comprises at least two filter medium sheets and at least one diffusion layer positioned between at least two successive filter medium sheets.

Claim 4

Dependent Claim 15 words

The fluid treatment element of claim 2, wherein said tube has a substantially cylindrical cross-section.

Claim 5

Dependent Claim 20 words

The fluid treatment element of claim 3, wherein at least two of said filter medium sheets have different pore ratings.

Claim 6

Dependent Claim 39 words

The fluid treatment element of claim 4, wherein said filter medium sheets having different pore ratings are arranged such that said filter medium sheet pore ratings decrease in the normal direction of fluid flow through said fluid treatment element.

Claim 7

Dependent Claim 18 words

The fluid treatment element of claim 5, wherein said diffusion layers are helically wrapped around said cylindrical tube.

Claim 8

Dependent Claim 24 words

The fluid treatment element of claim 6, wherein said filter medium sheets comprise a fibrous mass of nonwoven fibers secured to said diffusion layers.

Claim 9

Dependent Claim 18 words

The fluid treatment element of claim 7, wherein said filter medium sheets and said diffusion layers comprise polypropylene.

Claim 10

Dependent Claim 34 words

The fluid treatment element of claim 8, wherein said fluid treatment element comprises at least three filter medium sheets and at least one diffusion layer positioned between at least two successive filter medium sheets.

Claim 11

Dependent Claim 57 words

The fluid treatment element of claim 9, wherein said fluid treatment element comprises an innermost filter medium sheet positioned such that said diffusion layer associated therewith is oriented inwardly toward said cylindrical core and at least five additional filter medium sheets positioned such that said diffusion layers associated therewith are oriented outwardly away from said cylindrical core.

Claim 12

Dependent Claim 24 words

The fluid treatment element of claim 3, wherein said filter medium sheets are helically wrapped to form abutting edges of said filter medium sheets.

Claim 13

Dependent Claim 33 words

The fluid treatment element of claim 3, wherein said filter medium sheets are helically wrapped to form an overlap of about 25% to about 75% of the width of said filter medium sheets.

Claim 14

Dependent Claim 30 words

The fluid treatment element of claim 3, wherein said filter medium sheets are helically wrapped to form an overlap of about 67% of the width of said filter medium sheets.

Claim 15

Dependent Claim 30 words

The fluid treatment element of claim 3, wherein said filter medium sheets are helically wrapped to form an overlap of about 50% of the width of said filter medium sheets.

Claim 16

Dependent Claim 17 words

The fluid treatment element of claim 1, wherein said diffusion layer is helically wrapped around said tube.

Claim 17

Dependent Claim 22 words

The fluid treatment element of claim 15, wherein said diffusion layer is helically wrapped to form abutting edges of said diffusion layer.

Claim 18

Dependent Claim 14 words

The fluid treatment element of claim 16, wherein said diffusion layer is a mesh.

Claim 19

Dependent Claim 22 words

The fluid treatment element of claim 1, wherein a diffusion layer is positioned between the innermost filter medium sheet and said tube.

Claim 20

Dependent Claim 22 words

The fluid treatment element of claim 18, which element further comprises a pervious protective layer wrapped around the outermost filter medium sheet.

Claim 21

Dependent Claim 16 words

The fluid treatment element of claim 1, which element comprises at least two filter medium sheets.

Claim 22

Dependent Claim 38 words

The fluid treatment element of claim 20, wherein at least two of said filter medium sheets have different pore ratings and are arranged such that the pores of the filter medium sheets decrease in the radially outward direction.

Claim 23

Dependent Claim 34 words

The fluid treatment element of claim 1, wherein said filter medium sheet comprises a material selected from the group consisting of nylon, aramid, fluoropolymer, polyethylene, polyester, polystyrene, polyurethane, glass, carbon, stainless steel, and aluminum.

Claim 24

Dependent Claim 14 words

The fluid treatment element of claim 22, wherein said filter medium sheet comprises fiberglass.

Claim 25

Dependent Claim 32 words

The fluid treatment element of claim 1, wherein said filter medium is helically wrapped to form an overlap of about 25% to about 75% of the width of said filter medium sheet.

Claim 26

Dependent Claim 29 words

The fluid treatment element of claim 1, wherein said filter medium is helically wrapped to form an overlap of about 67% of the width of said filter medium sheet.

Claim 27

Dependent Claim 29 words

The fluid treatment element of claim 1, wherein said filter medium is helically wrapped to form an overlap of about 50% of the width of said filter medium sheet.

Claim 28

Dependent Claim 87 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least one filter medium sheet comprising a fibrous mass of nonwoven microfibers capable of removing particulates from a fluid helically wrapped around a pervious, hollow tube and at least one diffusion layer which allows for lateral flow of said fluid within said fluid treatment element, wherein said diffusion layer is a spun-bonded polypropylene nonwoven sheet material having a weight of between about 20 g/m 2 and about 60 g/m 2 .

Claim 29

Dependent Claim 87 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least one filter medium sheet comprising a fibrous mass of nonwoven microfibers capable of removing particulates from a fluid helically wrapped around a pervious, hollow tube and at least one diffusion layer which allows for lateral flow of said fluid within said fluid treatment element, wherein said diffusion layer is a spun-bonded polypropylene nonwoven sheet material having a weight of between about 20 g/m 2 and about 60 g/m 2 .

Claim 30

Dependent Claim 27 words

The fluid treatment element of claim 27, wherein said diffusion layer is a spun-bonded polypropylene nonwoven sheet material having a weight of about 20 g/m 2 .

Claim 31

Dependent Claim 27 words

The fluid treatment element of claim 27, wherein said diffusion layer is a spun-bonded polypropylene nonwoven sheet material having a weight of about 40 g/m 2 .

Claim 32

Dependent Claim 152 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least six filter medium sheets helically wrapped around a pervious, hollow, cylindrical tube to form an overlap of 50% of the width of each of said filter medium sheets, wherein each of said filter medium sheets comprises a fibrous mass of nonwoven polypropylene fibers secured to a diffusion layer comprising a porous polypropylene substrate, the innermost of said filter medium sheets is positioned such that said diffusion layer associated therewith is oriented inwardly toward said cylindrical core, the other filter medium sheets are positioned such that said diffusion layers associated therewith are oriented outwardly away from said cylindrical core, and at least three of said filter medium sheets have different pore ratings and are positioned such that said filter medium sheet pore ratings decrease in the normal direction of fluid flow through said fluid treatment element.

Claim 33

Dependent Claim 152 words

An element for treating a fluid flowing through the element, which fluid treatment element comprises at least six filter medium sheets helically wrapped around a pervious, hollow, cylindrical tube to form an overlap of 50% of the width of each of said filter medium sheets, wherein each of said filter medium sheets comprises a fibrous mass of nonwoven polypropylene fibers secured to a diffusion layer comprising a porous polypropylene substrate, the innermost of said filter medium sheets is positioned such that said diffusion layer associated therewith is oriented inwardly toward said cylindrical core, the other filter medium sheets are positioned such that said diffusion layers associated therewith are oriented outwardly away from said cylindrical core, and at least three of said filter medium sheets have different pore ratings and are positioned such that said filter medium sheet pore ratings decrease in the normal direction of fluid flow through said fluid treatment element.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-02-28	1997-08-30	1998-03-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-02-28	2001-08-30	2002-03-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-02-28	2005-08-30	2006-03-01	$7700.00	Window Closed / Lapsed

Helical wrapped filter element

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