# US 6,158,477 A · Flexible duct and method of making same

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- Number: US 6,158,477 A
- Document ID: US6158477A
- Status: Granted
- Kind: A
- Application number: 09/215,816
- Filed: 1998-12-18
- Granted: 2000-12-12
- Earliest claimed: 1998-12-18
- Assignees: Flexible Technologies, Inc.
- Inventors: Michael J. Waters
- Web page: https://patentgrep.com/patent/US6158477A

## CPC

- F16L 11/088: {comprising a combination of one or more layers of a helically wound cord or wire with one or more braided layers}
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL

## Abstract

A flexible duct and method for making the duct are disclosed. The duct includes an inner wall bonded to an outer wall, with a wire resilient helix and a scrim sandwiched therebetween. The scrim is in the form of a helical tape embedded between the outer wall and the inner wall, and preferably consists of a bonded yarn constructed in a layered or interwoven square or other uninterrupted geometrical pattern. The presence of the scrim provides the duct with high tensile strength and excellent tear resistance in all directions, especially in the helical direction. The method of manufacturing the duct includes the steps of helically forming the wire and scrim about the inner wall and bonding the outer wall to the inner wall to as to sandwich the helix and the scrim between the inner and outer walls.

## Claims

### Claim 1

A flexible duct comprising:
(a) an inner wall formed of helically-overlapping tape of a predetermined width;
(b) an outer wall formed of helically-overlapping tape of a predetermined width overlying said inner wall and having a bond formed therewith;
(c) a resilient helical member disposed and retained between said inner and outer walls; and
(d) a strengthening scrim formed of helically-disposed tape comprising a plurality of bonded multiple yarn having a layered, geometrical uninterrupted pattern disposed and retained between said inner and outer walls.

### Claim 2 (depends on 1)

A flexible duct according to claim 1, wherein said plurality of bonded multiple yarns has an interwoven, geometrical uninterrupted pattern.

### Claim 3 (depends on 1, 2)

A flexible duct according to claim 1 or 2, wherein said geometrical uninterrupted pattern is formed of two yarns and is rectangular.

### Claim 4 (depends on 1, 2)

A flexible duct according to claim 1 or 2, wherein said geometrical uninterrupted pattern formed of three yarns, two of said yarns forming a diamond pattern and the third of said yarns being disposed horizontally on said diamond pattern.

### Claim 5 (depends on 1)

A flexible duct according to claim 1, wherein said resilient helical member is positioned approximately at the mid-width point of the tape used to form the outer wall and approximately at the overlapping portions of the tape used to form the inner wall.

### Claim 6 (depends on 1)

A flexible duct according to claim 1, wherein said bond is formed between said inner wall and said outer wall by adhesive applied to at least one of said tapes forming said inner wall and said outer wall.

### Claim 7 (depends on 1)

A flexible duct according to claim 1, wherein said bond is formed between said inner wall and said outer wall by adhesive applied to both of said tapes forming said inner wall and said outer wall.

### Claim 8 (depends on 1)

A flexible duct according to claim 1, wherein said bond is formed between said inner wall and said outer wall by thermal fusion.