Blowable flexible inner duct

Abstract

The blowable flexible internal duct includes an outer internal duct structure and an inner internal duct structure. The outer internal duct structure includes at least one outer longitudinal chamber formed from at least one fabric. The inner internal duct structure includes at least one inner longitudinal chamber, each inner longitudinal chamber disposed within an outer internal duct fabric chamber, and the at least one inner longitudinal chamber includes an inflatable tube. The inflatable tube has a wall thickness of less than about 0.5 mm. Only the inner longitudinal chamber has an air permeability of less than about 1 cfm, only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and both the outer and inner longitudinal fabric chambers have an air permeability of less than about 1 cfm.

Description

[Technical field]

[0001] This invention relates to blowable fabric internal ducting, particularly for use in ducting systems. [Background technology]

[0002]

[0002] Flexible internal duct structures have chambers and are used within conduits to help separate individual cables into compartments or channels within the internal duct, to maximize the number of cables that can be placed within the conduit, and to facilitate insertion of the cables into the conduit by preventing cable-to-cable friction and providing tape or rope within each compartment of the internal duct.

[0003]

[0003] To form two or more chambers within an internal duct structure, a seam is typically used to attach layers together (which can be multiple pieces of fabric, fabric folded on itself, or a combination of both). In some applications, the cable is pulled through the internal duct chamber, while in other applications, the cable is preferably blown into the chamber. To be able to blow into the internal duct, the chamber needs to be air-tight (or essentially air-tight) and strong enough not to burst under the blowing pressure.

[0004]

[0004] In addition to being able to be pulled or pushed into a conduit / inner duct, it is desirable to have a blowable flexible inner duct that allows the inner duct and / or the cable within the inner duct to be blown into the conduit using air or another compressed gas. Summary of the Invention

[0005] In one embodiment, the present invention relates to a blowable flexible internal duct including an outer internal duct structure and an inner internal duct structure. The outer internal duct structure includes at least one outer longitudinal chamber formed from at least one fabric. The inner internal duct structure includes at least one inner longitudinal chamber, each inner longitudinal chamber disposed within an outer internal duct fabric chamber, and the at least one inner longitudinal chamber includes an inflatable tube. The inflatable tube has a wall thickness of less than about 0.5 mm. Only the inner longitudinal chamber has an air permeability of less than about 1 cfm, only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and both the outer and inner longitudinal fabric chambers have an air permeability of less than about 1 cfm.

[0006] In another embodiment, the present invention relates to a conduit system including a conduit and a blowable flexible inner duct disposed within the conduit. The blowable flexible internal duct includes an outer internal duct structure and an inner internal duct structure. The outer internal duct structure includes at least one outer longitudinal chamber formed from at least one fabric. The inner internal duct structure includes at least one inner longitudinal chamber, each inner longitudinal chamber disposed within an outer internal duct fabric chamber, and the at least one inner longitudinal chamber includes an inflatable tube. The inflatable tube has a wall thickness of less than about 0.5 mm. Only the inner longitudinal chamber has an air permeability of less than about 1 cfm, only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and both the outer and inner longitudinal fabric chambers have an air permeability of less than about 1 cfm.

[0007]

[0007] In another embodiment, the present invention relates to a process for forming a blowable flexible internal duct, comprising forming an internal internal duct structure having at least one internal longitudinal chamber, the at least one internal longitudinal chamber comprising an inflatable tube. The process also includes forming an outer internal duct structure including at least one outer longitudinal chamber formed from at least one fabric, and simultaneously inserting at least one inner longitudinal chamber into at least one of the outer longitudinal chambers while forming the outer internal duct structure. The inflatable tube has a wall thickness of less than about 0.5 mm. Only the inner longitudinal chamber has an air permeability of less than about 1 cfm, only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and the outer longitudinal fabric chamber, together with the inner longitudinal chamber located inside the outer longitudinal fabric chamber, has an air permeability of less than about 1 cfm. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 illustrates one embodiment of a conduit system in which the outer internal ductwork is a seamless tube. [Figure 2A]

[0009] FIG. 2A shows the relationship between the outer and inner internal ductwork during installation and use. [Figure 2B] FIG. 2B shows the relationship between the outer and inner internal ductwork during installation and use. [Figure 2C] FIG. 2C shows the relationship between the outer and inner internal ductwork during installation and use. [Diagram 3]

[0010] FIG. 3 illustrates one embodiment of a conduit system in which the outer internal ductwork is a number of seamless tubes attached to one another. [Figure 4]

[0011] FIG. 4 shows an embodiment of the conduit system where the outer internal ductwork is a pipe with a seam. [Diagram 5]

[0012] FIG. 5 shows one embodiment of a conduit system where the outer internal duct structure is a tube with a seam such that two chambers are formed. [Figure 6]

[0013] FIG. 6 shows one embodiment of a conduit system where the outer internal ductwork is multiple tubes attached together at seams. [Figure 7]

[0014] FIG. 7 illustrates one embodiment of a conduit system in which the outer internal duct structure has a teardrop configuration with one chamber. [Figure 8]

[0015] FIG. 8 illustrates one embodiment of a conduit system in which the outer internal duct structure has a teardrop configuration with multiple chambers. [Figure 9]

[0016] FIG. 9 illustrates one embodiment of a multi-chamber conduit system with an exterior internal duct structure formed from a single strip of fabric. [Figure 10]

[0017] FIG. 10 is a photograph of one embodiment of a blowable flexible inner duct. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0018] Figure 1 illustrates a conduit system 10. The conduit 200 (as shown in Figure 1) into which the internal duct structure is inserted may be of any suitable size (inner or outer diameter), material, and length. The conduit may also be referred to as a duct, a pipe, an elongated cylindrical element, etc. Typically, the conduit 200 is made of a polymer, although other materials such as metals may be used.

[0010]

[0019] In one embodiment, the conduit 200 is a very small conduit having an inner diameter of less than about 75 mm, more preferably less than about 60 mm, more preferably less than about 50 mm, more preferably less than about 40 mm, more preferably less than about 35 mm, more preferably less than 33 mm, more preferably less than 30 mm. In another embodiment, the conduit 200 is a medium to large conduit having an inner diameter of greater than about 100 mm, more preferably between about 1 and 3 inches, more preferably between about 3 and 10 inches.

[0011]

[0020] The blowable internal ducting structure 310 includes an outer internal ducting structure 100 and an inner internal ducting structure 115. The outer internal ducting structure 100 includes at least one outer longitudinal fabric chamber. The inner internal ducting structure 115 includes at least one inner longitudinal chamber 110 (FIG. 1) in which pull tapes, cables, etc. are to be placed, with each inner longitudinal chamber 115 being placed within the outer internal duct fabric chamber 100.

[0012]

[0021] The blowable flexible inner duct 310 has a longitudinal length and a cross-sectional area. In one embodiment useful for smaller conduits, the blowable flexible internal duct 310 has a width of less than about 100 mm, more preferably less than about 75 mm, more preferably less than about 50 mm. The width of the fabric internal duct is measured by flattening the fabric internal duct structure (as the natural cross-sectional state of the internal duct is circular or the lobes may be slightly rounded and therefore the width may appear smaller) and then the maximum measurement across the cross-sectional area is defined to be the width. In one embodiment, the width of the fabric internal duct structure is less than about 35 mm, more preferably less than about 30 mm.

[0013]

[0022] The outer internal ducting 100 includes at least one fabric arranged such that the outer internal ducting 100 includes at least one outer longitudinal chamber. The shape and structure of the outer internal ducting 100 may be any suitable shape so long as it is formed by a fabric and includes at least one outer longitudinal chamber.

[0014]

[0023] Referring to FIG. 1, one embodiment of the outer internal ducting structure 100 is shown that is a seamless fabric tube (shown in the conduit 200 of the conduit system 10). The seamless fabric tube may be formed, for example, using a circular weave or knit. The seamless tube may be formed in any suitable width. In one embodiment for smaller conduits, the width of the seamless tube is less than about 60 mm, more preferably less than about 50 mm, more preferably less than about 40 mm. A seamless tube may be preferred in some embodiments because further processing of the fabric may not be required after the tube is formed into the outer internal ducting structure 100, and the tube may be formed in a small width. In another embodiment, the fabric may be a shuttle weave fabric.

[0015]

[0024] Small seamless tubes may be used singly as shown in FIG. 1 or in multiples. Multiple separate seamless tubes may be placed in the conduit simultaneously or sequentially with the tubes not attached to each other (in one embodiment, the tubes may be temporarily attached to each other during installation to facilitate insertion into the conduit). In another embodiment shown in FIG. 3, multiple (at least two) seamless tubes may be joined together before being inserted into the conduit. FIG. 3 shows an exterior internal duct structure 100 including three seamless tubes connected along one of the sides of the tubes using attachments 300.

[0016]

[0025] The attachment 300 may be formed using any suitable method. In one preferred embodiment, the attachment 300 is a sewn seam made by sewing layers of fabric together. Other methods of forming the attachment include stapling, riveting, ultrasonically welding the fabric at intervals along its length, or fastening the fabric with a hot melt or solvent-based adhesive. The fabric may also be provided with relatively low temperature molten fibers that can melt and cool, thereby fusing the structure together at the attachment.

[0017]

[0026] The attachment 300 may be on one of the sides of the internal duct as shown in FIG. 3, or towards the center of the tube, which serves to divide each tube into two chambers. This attachment may be at a different location on each tube. The three outer internal duct structures in FIG. 3 form three outer longitudinal chambers. In each of these outer longitudinal chambers there is an inner duct longitudinal structure 115 that forms inner longitudinal chambers 110, 120, and 130. If the attachment 300 is in the center of the internal duct structure 100 in FIG. 3, six chambers are formed (but each chamber is smaller). The outer and inner internal duct structures may be different sizes and the attachment may be at different points within the blowable flexible internal duct.

[0018]

[0027] In another embodiment, as shown in FIG. 4, another embodiment of a blowable flexible internal duct as part of a conduit system 10 is shown, where the outer internal duct structure 100 is a seamed tube made from fabric with one seam along its longitudinal length to form a tube. The seamed tube includes one inner internal duct structure 115 forming an inner longitudinal chamber 110 and is formed from a strip of fabric material, which is then made into a tube with a seam 350 along the longitudinal length of the tube. This seam 350 can be a stitch, ultrasonic weld, melt, or any other suitable attachment means.

[0019]

[0028] Creating tubes from textile material in strip form instead of seamless tubes (e.g. using circular weaving or knitting) has many advantages. The first advantage is the perimeter of splicing. It is much easier to splice textile material in flat strip form to create longer lengths and then make the strip into a tube than to splice a seamless tube. Secondly, tubes of different sizes can be more easily produced with less machine downtime. Tubes with different diameters can be made by simply slitting the textile material in strip form to different widths before making it into a tube. In many seamless tube manufacturing processes, the warp and / or weft threads must be redone to change the diameter of the tube produced.

[0020]

[0029] The spliced ​​tube may be used as is, as shown in FIG. 4, or may have an attachment 300 that divides the tube into multiple chambers, as shown in FIG. 5. The outer internal duct structure 100 of FIG. 5 includes an attachment 300 that forms two outer longitudinal chambers. Each of these outer longitudinal chambers includes an inner internal duct structure 115 that forms an inner longitudinal chamber 110, 120. In one embodiment, the attachment 300 is in a central blowable flexible inner duct that is defined to be approximately equidistant from the two edges of the structure. This is preferable to form chambers of approximately the same size. In another embodiment, the attachment 300 is off-center, meaning that the attachment is not in the center of the structure. This creates a chamber that is larger than the chamber on the other side. This may be preferable to accommodate wires, cables 800, pull tapes 900, etc. of various sizes.

[0021]

[0030] In another embodiment shown in Figure 6, the exterior internal ductwork 100 includes multiple seamed fabric tubes attached to one another by attachments 300. The seams 350 may be located at any suitable location around the circumference of the tubes, and even in the area of ​​the attachments 300 themselves. The seams of each tube within the interior ductwork 100 may be in different locations.

[0022]

[0031] In one embodiment, the attachment 300 is in the center of a middle region defined to be approximately equidistant from the two edges of the structure. This is preferable to create chambers of approximately equal size. In another embodiment, the attachment 501 is off-center, meaning that the attachment is not in the center of the structure. This makes the chamber on one side of the margin region larger than the chamber on the other side of the margin region. This may be preferable to accommodate wires, cables, pull tapes, etc. of various sizes.

[0023]

[0032] In FIG. 7, the outer internal ducting structure 100 is in the form of a single teardrop configuration within a conduit 200. In the case of a single teardrop, a strip-shaped fabric is folded around its longitudinal axis and the edges are attached to each other with attachments 300. This forms an outer longitudinal chamber that includes an inner longitudinal chamber 110. Inside the chamber 110, pull tapes, cables, mini-cables, etc. can be placed. In one embodiment, the edges of the strip-shaped fabric of the outer internal ducting structure 100 are folded over to improve seam strength and reduce friction.

[0024]

[0033] In another embodiment shown in FIG. 8, the outer internal duct structure 100 is a multi-chamber teardrop configuration. The inner duct structure of FIG. 8 includes two outer longitudinal chambers, but the inner duct structure can include any suitable number of outer longitudinal chambers, such as two or more, three or more, four or more, five or more, or six or more. In one embodiment, the multi-chamber teardrop configuration can be formed from multiple strip-shaped lengths of fabric folded to form individual compartments, which are then attached to each other. The outer internal duct structure 100 is configured with a common seam that secures the folds as well as the cut edges along the length of the fabric that is folded under to improve seam strength and reduce friction. In another embodiment, the teardrop shape and chambers can be formed from a single piece of fabric that is folded over multiple times. This embodiment is shown in FIG. 8, where a single strip-shaped piece of fabric is folded and attached to form two outer longitudinal chambers. Inside each of these chambers is an inner internal duct structure 115.

[0025]

[0034] Referring to Figure 9, another embodiment of a blowable flexible internal duct in a conduit 200 is shown. The external internal duct structure 100 includes three regions: a first region, a middle region, and a second region. In the external internal duct structure 100 of Figure 9, the structure 100 includes one stripe-shaped fabric that forms four flexible outer longitudinal chambers. Each of the outer chambers includes an inner longitudinal chamber.

[0026]

[0035] For the embodiment shown in FIG. 9, each strip-shaped fabric has a first edge and a second edge. The first and second edges are located in a middle region of the flexible internal duct structure. Each fabric strip extends outward from a middle region to either a first region or a second region, and then returns to the middle region to form an outer longitudinal chamber. The internal duct structure may include two or more strip-shaped fabrics, at least one of which extends from a first region to a second region. The internal duct structure includes at least one strip-shaped fabric that includes a fold in the first region and a fold in the second region.

[0027]

[0036] In one preferred embodiment, the desired number of chambers can be created with a minimum number of strip-shaped fabric edges in the central region of the structure 100 so that all of the chambers are formed from a single strip-shaped fabric as shown in FIG.

[0028]

[0037] In some embodiments, the edges of the strip-shaped fabric are folded over, which may be preferred to prevent the edges of the fabric from catching on other materials during manufacture, installation, and / or use of the internal duct structure, and also helps to prevent the edges of the strip-shaped fabric from coming off the attachment 300. For example, the attachment 300 may be a line of stitches, and if there is some fraying of the edges of the strip-shaped fabric, some of the fabric may become loose and one or more of the chambers may not be fully closed.

[0029]

[0038] Preferably, the fabrics of the outer longitudinal structure are only attached to each other and to themselves with attachments 300, but not to the first region, the second region, the first edge, or the second edge. This allows the chamber to expand and better fill the conduit. In the structure shown in Figure 9, when placed in a conduit, the chamber of the blowable flexible inner duct expands to fill the conduit and has the appearance of a dragonfly or butterfly in cross section.

[0030]

[0039] In one embodiment, the attachment 300 is in the center of a middle region defined to be approximately equidistant from the two edges of the structure. This is preferable for creating chambers of approximately equal size. In another embodiment, the attachment means 300 is off-center, meaning that the attachment means is not in the center of the structure. This makes the chamber in one region larger than the chamber in the other region. This is preferable for accommodating wires, cables, pull tapes, etc. of various sizes.

[0031]

[0040] In one preferred embodiment, the outer internal duct structure 100 is preferably made using a woven fabric. The fabric has a number of warp threads that run in the warp direction of the fabric. The woven fabric also includes a number of weft threads that run generally perpendicular to the warp direction of the fabric. The weft threads are interwoven with the warp threads, and the warp threads extend above and below the weft threads in a predetermined cross pattern. In one preferred embodiment, the fabric is a plain weave fabric. The fabric may be any other suitable weave pattern, including twill and satin. In other embodiments, nonwoven fabrics or knits may be used as the fabric for the outer internal duct structure.

[0032]

[0041] The yarns in the woven fabric may be any suitable yarn. The type, size, and comparative selection of each yarn in the woven fabric contributes to the final product of the woven fabric. In this application, "yarn" as used herein includes monofilament elongated bodies, multifilament elongated bodies, ribbons, strips, threads, tapes, fibers, and the like. The woven fabric may contain one type of yarn, or a plurality of any one or combination of the above. The yarns may be in any suitable form, such as spun staple yarns, monofilaments, or multifilaments, single component, bicomponent, or multicomponent, and may have any suitable cross-sectional shape, such as round, multi-lobal, square or rectangular (tape), and elliptical.

[0033]

[0042] The textile can be formed from a single yarn or type of yarn (e.g., the textile can be formed only from yarns that include a blend of cellulose and synthetic fibers such as polyamide fibers), or the textile can be formed from several yarns or types of yarns (e.g., the textile can be formed from a first yarn that includes cellulose and polyamide fibers, and a second yarn that includes inherent flame resistant fibers). The yarns may be formed from (but are not limited to) cellulosic fibers (such as cotton, rayon, linen, jute, hemp, cellulose acetate, and combinations, mixtures, or blends thereof), polyester fibers (e.g., poly(ethylene terephthalate) fibers, poly(propylene terephthalate) (PET) fibers, poly(trimethylene terephthalate) fibers), poly(butylene terephthalate) fibers, and blends thereof), polyamide fibers (e.g., nylon 6 fibers, nylon 6,6 fibers, nylon 4,6 fibers, and nylon 12 fibers), polyvinyl alcohol fibers, elastic polyester-polyurethane copolymers (SPANDEX®), flame retardant meta-aramids (NOMEX®), and combinations, mixtures, or blends thereof. Certain embodiments of the fabrics of the present invention contain yarns that include inherently flame resistant fibers. As utilized herein, the term "intrinsic flame resistant fibers" refers to synthetic fibers that exhibit flame retardancy without the need for further flame retardant treatment due to the chemical composition of the material from which they are made. In such embodiments, the inherently flame resistant fibers may be any suitable inherently flame resistant fibers, such as polyoxadiazole fibers, polysulfonamide fibers, poly(benzimidazole) fibers, poly(phenylene sulfide) fibers, meta-aramid fibers, para-aramid fibers, polypyridobisimidazole fibers, polybenzylthiazole fibers, polybenzyloxazole fibers, melamine-formaldehyde polymer fibers, phenol-formaldehyde polymer fibers, oxidized polyacrylonitrile fibers, polyamide-imide fibers, and combinations, mixtures, or blends thereof.In certain embodiments, the inherent flame resistant fibers are preferably selected from the group consisting of polyoxadiazole fibers, polysulfonamide fibers, poly(benzimidazole) fibers, poly(phenylene sulfide) fibers, meta-aramid fibers, para-aramid fibers, and combinations, mixtures, or blends thereof.

[0034]

[0043] In a preferred embodiment, the warp yarns are monofilament yarns. Monofilament yarns may be preferred due to a lower amount of crimp in the woven fabric (compared to multifilament yarns), and therefore the monofilament yarns have less elongation when the internal duct is pulled through the conduit. By way of example, the warp yarns may be selected from polyolefins such as polyester, polypropylene, polyethylene and ethylene-propylene copolymers, as well as polyamides such as nylon and aramids, e.g., Kevlar®. Yarns having a peak elongation at peak tensile load of 45% or less, preferably 30% or less, are preferred. Monofilament yarns, including bicomponent and multicomponent yarns, have been found to be particularly useful in internal duct applications. These materials have been found to impart desired properties to the woven fabric. In one embodiment, all of the warp yarns are PET monofilament yarns, as PET monofilament yarns have a good balance of properties versus cost.

[0035]

[0044] By selecting warp yarns that have a relatively low elongation at peak tensile load, it is possible to minimize the longitudinal elongation of the internal duct structure during installation of the internal duct within the conduit, thereby avoiding "bunching" of the internal duct. Furthermore, the possibility of elongation in the warp direction of the fabric incorporated in the internal duct can be minimized by reducing the crimp of the warp yarns during the weaving process. For example, warp crimp can be reduced by increasing the tension on the warp yarns during weaving to achieve a warp crimp of less than 5% as measured by ASTM D3883-Standard Test Method for Yarn Crimp and Yarn Take-Up in Woven Fabrics. Reducing the warp crimp of a fabric, particularly a plain weave fabric, results in an increase in the crimp of the weft yarns, which has the additional benefit of increasing the strength of the seams along the longitudinal edges of the section of fabric used to construct the internal duct.

[0036]

[0045] In one embodiment, warp yarns having a denier of 350 to 1,200, preferably 400 to 750, can be used. The end count (threads per inch in the warp) typically ranges from 25 to 75 ends per inch, preferably 35 to 65 ends per inch. In one embodiment of the present invention, a plain weave fabric is provided having monofilament polyester warp yarns of 400 to 750 denier, 35 to 65 ends per inch.

[0037]

[0046] The weft yarn may be any suitable yarn including polyolefins such as polyester, polypropylene, polyethylene, and ethylene-propylene copolymers, as well as polyamides such as nylon and aramids, e.g., Kevlar®, and mixtures thereof. Yarns having a peak elongation at peak tensile load of 45% or less, preferably 30% or less, are preferred.

[0038]

[0047] The terms "pick," "picks," "picks per inch," and "ppi" are intended to refer to (a) one weft yarn that is carried through a shed formed during the weaving process and interwoven with the warp yarns, and (b) two or more weft yarns that are carried separately or together through a shed and interwoven with the warp yarns during the weaving process. Thus, for purposes of determining the picks per inch of a fabric, a multiply inserted weft yarn counts as a single pick.

[0039]

[0048] The terms "multiple insertion" and "double insertion" are intended to include (a) multiple wefts that are inserted together into the loom shed, (b) multiple wefts that are inserted separately while the loom shed remains the same, and (c) multiple wefts that are inserted separately while the loom shed remains substantially the same, i.e., the positions of 25% or less of the warp yarns change between yarn insertions. In one preferred embodiment, at least some of the weft picks are multiple insertions.

[0040]

[0049] Other suitable weave patterns may be used as the weave pattern in the first weaving zone. The terms "woven" and "interwoven" are meant to include any structure incorporating interengaging forming strips. By way of example only and not limitation, it is contemplated that a weft yarn may pass over two or more adjacent warp yarns 100 before moving into position under one or more adjacent warp yarns, thereby forming a so-called twill weave. Suitable twill weaves include both warp and weft twills, such as 2 / 1, 3 / 1, 3 / 2, 4 / 1, 1 / 2, 1 / 3, or 1 / 4 twills. The fabric may also be, for example, satin, basket weave, poplin, jacquard, and crepe weave fabrics. In one embodiment, it may be included in a woven fabric.

[0041]

[0050] The fabric may include one weave pattern along the length of the fabric, or may have different zones of weave patterns that vary along the machine direction of the fabric. In embodiments in which the fabric includes multiple zones, the first weave zone may have any suitable weave pattern. FIG. 10 shows one possible weave pattern in which the warp and weft yarns in the first weave zone are plain weave, with each weft yarn passing over the warp yarn and then under the adjacent warp yarn in a repeat across the full width of the fabric. Suitable plain weaves include, but are not limited to, ripstop weaves, which are produced by incorporating additional or reinforcing yarns, at regular intervals, into the warp, weft, or both warp and weft yarns of the fabric material during formation. Plain weaves are preferred because they provide stability and structure to the fabric. If the first weave zone is too small or eliminated entirely, the fabric may be too loose (warp and weft yarns move too easily relative to each other) and not suitable for internal duct construction. In one embodiment, the woven fabric may be a partial float woven fabric as described in Patent Nos. 10,254,498, 10,829,874, and 11,008,680, which are incorporated herein by reference.

[0042]

[0051] In the weft direction, it is preferred to use a variety of different yarns to tailor the physical properties of the final fabric and structure. Monofilament yarns are stiffer than multifilament yarns (keeping denier and material the same). Multifilament yarns are more flexible. By using both monofilament and multifilament weft yarns, a balance between flexibility and stiffness is obtained. Also, by incorporating some multifilament yarns (due to their lower stiffness), the opening force of the internal ducts, i.e. the amount of force required to push the cable through the individual cells, is lowered. Multifilament yarns that are multiple or doubly inserted are preferred because they have a larger denier and therefore the cable "rides" along these ridges of the fabric. As the surface area of ​​the fabric in contact with the cable is smaller, friction is reduced and the pulling tension required to retract the cable is typically lower.

[0043]

[0052] In one embodiment, the fabric comprises a UV stabilizer. The stabilizer may be compounded or otherwise formed in the yarn, may be a coating on the yarn, or may be a coating on the entire fabric. It is somewhat counterintuitive to place a UV stabilizer on a product that goes underground in a pipe, but it is understood that a roll of interior ducting may be located outside of the elements and the sun for up to a year prior to installation. The UV stabilizer helps protect the physical properties of the fabric and interior ducting until it is installed and protected from UV sources. UV stabilizers include materials that inhibit photoinitiation (e.g., UV absorbers (UVA) and excited state quenchers) and materials that inhibit subsequent oxidation processes (e.g., radical scavengers and alkyl hydroperoxide decomposers). Any suitable UV stabilizer may be used, for example, carbon black, titanium dioxide, and hydrobenzophenone.

[0044]

[0053] Referring back to FIG. 1, the blowable flexible internal duct 310 includes an internal internal duct structure 115 that forms at least one internal longitudinal chamber 110. Each internal longitudinal chamber 110 is disposed within an outer longitudinal chamber formed by an outer internal duct structure. In the embodiment shown in FIG. 1, there is one internal longitudinal chamber within the outer longitudinal chamber, but there are embodiments in which two or more internal longitudinal chambers may be located within a single outer longitudinal chamber. In other embodiments in which there are multiple outer longitudinal chambers (such as FIG. 3), it is not necessary for all of the outer longitudinal chambers to include an inner longitudinal chamber, and it may be desirable for each of at least one outer longitudinal chamber not to include an inner longitudinal chamber.

[0045]

[0054] The inner longitudinal chamber comprises an inflatable tube. The tube can be any suitable inflatable tube, but is preferably air, vapor, and water impermeable, lightweight, and flexible. In one embodiment, the inflatable tube is seamlessly formed from a process such as blow extrusion. In another embodiment, the tube is formed from a thin plastic sheet folded on itself, and its edges are attached and sealed to each other. The edges may be sealed to align to form a teardrop-like shape to the tube, or the edges may be on top of each other to form a more circular cross-sectional shape. The bond may be formed from a pressure sensitive adhesive, a thermal adhesive, ultrasonic welding, or any other known manufacturing process.

[0046]

[0055] The inflatable tube may be made of any suitable material, including any thermoplastic and thermosetting resin. Preferably, the inflatable tube comprises a thermoplastic polymer. In one embodiment, the polymer is selected from the group consisting of low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), low-low density polyethylene (LLDPE), polypropylene (PP), polyester (PET), polyamide (PA). In one embodiment, the thermoplastic is polyethylene, preferably medium density polyethylene. The material forming the inflatable tube is preferably airtight (air impermeable), good strength at low weight, low friction, and low cost. The inflatable tube may contain a single polymer or a blend of polymers, may have additional fillers added to the polymer, and / or may have a single layer or may be coextruded to have multiple layers.

[0047]

[0056] Polyethylene has been found to have a low coefficient of friction (making it easier for cables or other elongated members to slide within the tube compared to materials with higher coefficients of friction such as some urethane elastomeric type materials). The expandable tube, in one embodiment, has a wall thickness of about 0.1 to 1 mm, more preferably less than about 0.5 mm, more preferably less than 0.25 mm. This thickness has been found to produce an expandable tube with good physical properties and be cost-effective. Expandable tubes having this thickness have also been shown to be sufficient to withstand (in combination with an external chamber) typical pressures used in cable and internal duct blowing systems (which are typically much lower than water-based systems).

[0048]

[0057] The goal of a blowable flexible inner duct is to have the strength and properties of a flexible inner duct while being nearly impermeable to air, vapor, and water, thereby allowing the blowable flexible inner duct and / or the cables placed within the inner duct structure to be blown. Some previous attempts to make a blowable flexible inner duct structure have included using a fabric with a coating thereon. Prototypes using coated fabrics tended to fail due to air leakage at the stitching (attachment areas) or the seams / stitching tended to fail during blow testing. The combination of an inner inner duct structure, an inflatable tube that provides air impermeability, and an outer inner duct structure, a fabric structure that provides strength, creates a blowable flexible inner duct. Air permeability is typically measured using ATSM D737. When combined into a blowable flexible inner duct, the inner and outer chambers exhibit a favorable low air permeability.

[0049]

[0058] The inner longitudinal chamber (which is an inflatable tube) alone is approximately 2 cm 3 / cm 2 / s (at 10 inches of water column) or less than 1 cfm, more preferably about 1 cm 3 / cm2 / s, more preferably less than about 0.5 cm 3 / cm 2 In another embodiment, the inner longitudinal chamber (which is an inflatable tube) alone has an air permeability of about 0 to 0.5 cm / s (at 10 inches of water). 3 / cm 2 / s, more preferably about 0.001 to 0.5 cm 3 / cm 2 / s, or more preferably has an air permeability of less than about 0.2 cfm.

[0050]

[0059] The outer longitudinal chamber (which is the fabric) preferably has a very open structure, meaning that a significant portion of the surface of the fabric is open or thread-free. This creates a very porous fabric through which air, water, and light can easily pass. By itself, the fabric can be approximately 5 cm 3 / cm 2 / s (at 10 inches of water column), more preferably about 10 cm 3 / cm 2 / s, more preferably about 25 cm 3 / cm 2 In another embodiment, the outer longitudinal chamber (which is the fabric) alone has an air permeability of about 5 to 200 cm / s, preferably greater than 100 cfm, and more preferably greater than 200 cfm. 3 / cm 2 / s (at 10 inches of water column), more preferably about 10 to 100 cm 3 / cm 2 / s air permeability.

[0051]

[0060] When the inner and outer inner duct chambers are combined to form a blowable flexible inner duct (the inner chamber is located within the outer chamber), the blowable flexible inner duct may be approximately 2 cm 3 / cm 2 / s (at 10 inches of water pressure), more preferably about 1 cm 3 / cm 2 / s, more preferably less than about 0.5 cm 3 / cm2 In another embodiment, the inner and outer inner duct chambers that combine to form a blowable flexible inner duct (the inner chamber disposed within the outer chamber) have an air permeability of about 0 to 0.5 cm. 3 / cm 2 / s (at 10 inches of water column), more preferably about 0.001 to 0.5 cm 3 / cm 2 In another embodiment, the inner and outer inner duct chambers that combine to form a blowable flexible inner duct (the inner chamber disposed within the outer chamber) have an air permeability of less than cfm, more preferably less than about 0.2 cfm.

[0052]

[0061] A custom test setup was used to perform the burst tests. The air regulator, valve, first pipe, inner duct structure to be tested, and second pipe are arranged in sequence with the end of the pipe opposite the inner duct capped. The inner duct structure is clamped onto the pipe and pressurized air is applied and slowly increased in steps over time until the inner duct breaks, leaks, or bursts. The maximum psi before the inner duct structure breaks (breaks, leaks, or bursts) is considered the burst strength. When combined with a blowable flexible inner duct, the inner and outer chambers assume a preferred high burst strength.

[0053]

[0062] In one embodiment, the inner longitudinal chamber (which is the expandable tube) alone has a burst strength of less than about 50 psi, more preferably less than about 35 psi. In another embodiment, the inner longitudinal chamber (which is the expandable tube) alone has a burst strength of about 5 to 40 psi, more preferably about 10 to 25 psi. In another embodiment, the inner longitudinal chamber (which is the expandable tube) alone has a burst strength of less than about 75 psi, more preferably less than about 70 psi. In another embodiment, the inner longitudinal chamber (which is the expandable tube) alone has a burst strength of between about 25 psi and 80 psi, more preferably between about 40 psi and 70 psi.

[0054]

[0063] The outer longitudinal chamber (which is fabric) is much stronger. When the inner and outer inner duct chambers are combined to form a blowable flexible inner duct (with the inner chamber disposed within the outer chamber), the blowable flexible inner duct has a burst strength of greater than about 50 psi, more preferably greater than about 60 psi, and in another embodiment about 55 to 100 psi.

[0055]

[0064] In one embodiment, the polymer forming the expandable tube preferably has an elongation to break of less than about 50%, more preferably less than about 30%. This is in contrast to other tubes which are more elastic and have an elongation to break of 200 to 300% or more. In other embodiments, the polymer forming the expandable tube preferably has an elongation to break of more than about 50%, more than about 100%, more preferably more than about 200%.

[0056]

[0065] Preferably, the inner internal duct chamber is movable within the outer internal duct chamber, meaning that the inner internal duct chamber can move relative to the outer internal duct chamber and is not permanently attached to the outer internal duct structure or is not attached at all.

[0057]

[0066] FIG. 2A shows an embodiment of a blowable flexible inner duct 310 in which an inner inner duct structure 115, which is an inflatable tube, is placed within an outer inner duct structure 100, which is a seamless fabric. The inner inner duct structure may be folded, crimped, or otherwise manipulated to make it easier to insert the inner inner duct structure into the outer inner duct structure. FIG. 2B shows how the blowable flexible inner duct 310 looks when air is introduced into the inner inner duct structure 115. The inner inner duct structure 115 expands or opens to fill the outer inner duct structure 100, which restrains the inner inner duct structure 115, providing burst strength to the inner inner duct structure 115 and preventing the inner inner duct structure 110 from bursting. FIG. 2C shows the blowable flexible inner duct 310 after air pressure has been released from the blowable flexible inner duct 310. In this case, the inner internal ducting 115 can remain against the inner surface of the outer internal ducting 100 or can shrink / contract / fold back away from the outer internal ducting 100 .

[0058]

[0067] The relative sizes of the two chambers are important because the outer internal duct structure 100 restrains the inner internal duct structure 115 and provides burst strength to the inner internal duct structure 110. If the inner longitudinal chamber is too small (has a diameter that is too small), it will burst or leak when it expands from air pressure before reaching the inner surface of the outer longitudinal chamber. The diameter of the longitudinal chamber is measured as the diameter when the chamber is completely flat. In one embodiment, the diameter of the inner longitudinal chamber is about 50 to 200%, more preferably about 60 to 100%, more preferably about 70 to 95%, more preferably about 75 to 90% of the outer longitudinal chamber. The more elastic (stretchable) the inner longitudinal chamber is made, the smaller the diameter it can be relative to the outer longitudinal chamber because it can stretch to the size of the outer longitudinal chamber without breaking. In another embodiment, the inner longitudinal chamber occupies at least about 60% of the cross-sectional area of ​​the outer longitudinal chamber. In preferred embodiments, the inner longitudinal chamber occupies at least about 75% of the cross-sectional area of ​​the outer longitudinal chamber, or from about 70 to 95% of the cross-sectional area of ​​the outer longitudinal chamber.

[0059]

[0068] The blowable flexible internal duct can be constructed in any suitable manner. In one embodiment, an outer internal duct structure is formed and then the inner longitudinal chamber from the inner internal duct structure is placed inside the outer longitudinal chamber. This is preferred to make the existing internal duct structure blowable. The inflatable tube may be pulled or blown into the existing internal duct structure (blowable or non-blowable) or piggybacked with a first cable that is blown or pulled into the internal duct structure.

[0060]

[0069] In another embodiment, the inner longitudinal chamber is inserted while the material (preferably fabric) of the outer internal duct structure is formed in at least one outer longitudinal chamber. In the case of a seamless tube as the outer longitudinal chamber as shown in Figures 1 and 3, the inflatable tube is introduced while the tube is being made (knitted, woven, circular woven, shuttle woven, etc.). At the same time as forming the outer internal duct structure, at least one inner longitudinal chamber is inserted into at least one of the outer longitudinal chambers.

[0061]

[0070] When the fabric is folded into the outer internal duct structure as shown in Figures 4 to 9, the inflatable tube is preferably introduced while the fabric is folded and secured within the chambers. At the same time as forming the outer internal duct structure, at least one inner longitudinal chamber is inserted into at least one of the outer longitudinal chambers.

[0062]

[0071] A blowable internal duct structure may be drawn, blown into, or incorporated into the conduit while the conduit is being manufactured. Cables or other elongated members disposed within the internal duct structure can be blown or drawn into the chamber.

[0063]

[0072] The figure also shows that in some embodiments, the interior chamber has a cable 800 and / or a pull tape or rope 900 therein. To pull optical fiber, coaxial cable, or other cable through the interior duct structure, in one embodiment, it is desirable to provide a pull line for such purpose. The pull line is preferably placed in a section of the interior duct prior to installation of the interior duct within the conduit. By way of example, the pull line may be a tightly woven, relatively flat strip of material, or may be a stranded rope or multi-layered cord having a substantially circular cross section. A pull line that is a pull rope is shown as element 900 in Figures 3, 5, 6, 8, and 9. In one embodiment, at least one of the interior chambers includes a cable.

[0064]

[0073] Preferably, the inner duct and the pull line have respective values ​​of elongation that are substantially equal for a given tensile load. If the elongation of the inner duct is substantially different from the elongation of the pull line, one of these structures may lag relative to the other when pulled together through the conduit during installation, resulting in bunching of the inner duct. The pull line may be formed from a tightly woven polyester material that exhibits a tensile strength of about 400 pounds to about 3,000 pounds. In one embodiment, the pull line is a pull tape having a flat cross-sectional shape. In another preferred embodiment, the pull line is a pull rope having a circular or oval cross-sectional shape. Pull ropes are preferred because the inner duct structures (and their associated chambers) are very small, and the pull rope takes up less space within the conduit. Preferably, the inner duct structures (all of the disclosed inner duct structures within this application) include at least one pull rope in at least one chamber. In another embodiment, each chamber of the inner duct structure includes a pull rope.

[0065]

[0074] In one embodiment, the internal duct structure contains a cable 800 after being placed in the conduit (or in another embodiment, before being placed in the conduit). Preferably, at least one of the chambers of the internal duct structure contains a cable. The cable 800 may be any suitable cable, small or large diameter. In one embodiment, the cable is a mini cable having a smaller diameter than a conventional cable. Preferably, the mini cable has a diameter of less than about 15 mm, more preferably less than about 11 mm. The term "cable" is intended to include fiber optic cables, electrical wires, coaxial and triaxial cables, and any other line for transmitting electrical and / or electromagnetic signals.

[0066]

[0075] The conduit 10 shown in the figures may be any suitable conduit, for example, the conduit may be made of metal, synthetic polymers such as thermoplastic polymers, clay, or concrete. The passages through the conduit may have circular, elliptical, rectangular, polygonal, or other cross-sectional shapes. The present invention finds utility in combination with virtually any conduit system. Depending on the relative size of the passages within the interior ducts, typically calculated as the inside diameter, one skilled in the art can select between the width of the interior ducts, the number of compartments within each interior duct, and the number of individual interior ducts to maximize the capacity of the conduit.

[0067] example

[0076] According to one embodiment of the present invention, a blowable flexible inner duct was made. Air permeability was tested using ASTM D737. A custom test setup was used to perform the burst test. The order is an air regulator, a valve, a first pipe, the inner duct structure to be tested, and a second pipe with the end of the pipe opposite the inner duct capped. The inner duct structure is clamped onto the pipe and pressurized air is applied and slowly increased in steps over time until the inner duct breaks, leaks, or bursts. The maximum psi before the inner duct structure breaks (breaks, leaks, or bursts) is considered the burst strength.

[0068]

[0077] Exterior Internal Duct Structure: A woven fabric was made having warp and weft yarns. The warp yarns were 520 denier monofilament polyester yarns with a 48 epi construction. The weft yarns were 350 denier nylon monofilament yarns alternating with 600 denier multifilament textured polyester yarns with a construction of 24 weft yarns per inch. The fabric was folded and sewn together as shown in the diagram in Figure 9 and the photograph in Figure 10 to create an exterior internal duct structure having a width of about 2.5 inches and including four exterior longitudinal chambers. The exterior longitudinal chambers each have a diameter of about 1.2 inches. The air permeability of the woven fabric was about 10 to 100 cm at 10 inches of water. 3 / cm 2 / s.

[0069]

[0078] Internal Inner Duct Construction: A plastic tube made from medium density polyethylene (MDPE) having a nominal wall thickness of about 7 mils (0.18 mm) and a folded diameter (defined as diameter in this application) of about inches. The air permeability of the plastic tube is about 0 cm at 10 inches of water. 3 / cm 2 The burst strength of the plastic tubing was approximately 18 psi.

[0070]

[0079] Four inner internal duct structures were added to the outer internal duct structure so that each outer longitudinal chamber contained one plastic tube. The inner tubes were approximately 87% of the diameter of the outer chamber. The air permeability of one outer longitudinal chamber with one inner tube inside was approximately 0 cm at 10 inches of water. 3 / cm 2 The burst strength of the outer longitudinal chamber and plastic tube combined was 90 psi.

[0071]

[0080] As can be seen from the above data, the combination of an inner longitudinal chamber inside an outer longitudinal chamber creates a blowable flexible inner duct having the desired low air permeability and high burst strength as is desired for a blowable flexible inner duct.

[0072]

[0081] All references cited in this specification, including publications, patent applications, and patents, are herein incorporated by reference to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and was set forth in its entirety herein.

[0073]

[0082] Use of the terms "a" and "an" and "the" and similar referents in the context of describing the subject matter of this application (particularly in the context of the claims below) should be construed to encompass both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise indicated. Recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value contained within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually recited herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly contradicted by context. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended merely to better clarify the subject matter of this application and does not impose any limitations on the scope of the subject matter unless otherwise asserted. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the subject matter described herein.

[0074]

[0083] Preferred embodiments of the subject matter of this application are described herein, including the best mode known to the inventors for carrying out the claimed subject matter. Variations of these preferred embodiments will become apparent to those skilled in the art upon reading the foregoing description. The inventors anticipate that those skilled in the art will employ such variations as appropriate, and the inventors intend for the subject matter described herein to be carried out otherwise than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or clearly contradicted by context.

Claims

1. A blowable flexible inner duct, an outer internal duct structure comprising at least one outer longitudinal chamber formed from at least one fabric; an inner internal duct structure comprising at least one inner longitudinal chamber, each inner longitudinal chamber being located within an outer internal duct fabric chamber, the at least one inner longitudinal chamber comprising an inflatable tube, the inflatable tube having a wall thickness of less than about 0.5 mm; A blowable flexible inner duct, wherein only the inner longitudinal chamber has an air permeability of less than about 1 cfm, and only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inside the outer longitudinal fabric chamber, has an air permeability of less than about 1 cfm.

2. 10. The blowable flexible inner duct of claim 1, wherein said outer longitudinal fabric chamber, together with an inner longitudinal chamber disposed inwardly of said outer longitudinal fabric chamber, has a burst strength of greater than about 60 psi.

3. 2. The blowable flexible inner duct of claim 1, wherein said inner longitudinal chamber occupies at least about 75% of a cross-sectional area of ​​said outer longitudinal chamber.

4. 10. The blowable flexible inner duct of claim 1, wherein the expandable tube has an elongation at break of greater than about 50%.

5. The blowable flexible inner duct of claim 1 , wherein the at least one fabric comprises a woven fabric.

6. The blowable flexible inner duct of claim 1 , wherein the inner longitudinal chamber is movable within the outer longitudinal fabric chamber.

7. 1. A conduit system comprising: a conduit; and a blowable flexible inner duct disposed within the conduit, the blowable flexible inner duct comprising: an outer internal duct structure comprising at least one outer longitudinal chamber formed from at least one fabric; an inner internal duct structure comprising at least one inner longitudinal chamber, each inner longitudinal chamber being located within an outer internal duct fabric chamber, the at least one inner longitudinal chamber comprising an inflatable tube, the inflatable tube having a wall thickness of less than about 0.5 mm; A conduit system, wherein only the inner longitudinal chamber has an air permeability of less than about 1 cfm, and only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inside the outer longitudinal fabric chamber, has an air permeability of less than about 1 cfm.

8. 8. The conduit system of claim 7, wherein the outer longitudinal fabric chamber, together with an inner longitudinal chamber disposed inwardly of the outer longitudinal fabric chamber, has a burst strength of greater than about 60 psi.

9. The conduit system of claim 7 , wherein the inner longitudinal chamber occupies at least about 75% of a cross-sectional area of ​​the outer longitudinal chamber.

10. The conduit system of claim 7 , wherein only the inner longitudinal chamber has a burst strength of less than about 35 psi.

11. 8. The conduit system of claim 7, wherein the outer internal duct structure comprises a strip of fabric having two longitudinal edges folded about a centrally located longitudinal axis and abutted along the longitudinal edges to define at least one outer longitudinal chamber, the fabric being folded about the centrally located longitudinal axis and abutted with stitches.

12. The conduit system of claim 7 , wherein the inner longitudinal chamber is movable within the outer longitudinal fabric chamber.

13. 1. A process for forming a blowable flexible internal duct, comprising: forming an inner internal duct structure comprising at least one inner longitudinal chamber, said at least one inner longitudinal chamber comprising an inflatable tube; forming a fabric; forming an outer internal duct structure from the fabric having at least one outer longitudinal chamber and simultaneously inserting at least one inner longitudinal chamber into at least one of the outer longitudinal chambers, the inflatable tube having a wall thickness of less than about 0.5 mm; wherein only the inner longitudinal chamber has an air permeability of less than about 1 cfm, and only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inside the outer longitudinal fabric chamber, has an air permeability of less than about 1 cfm.

14. 14. The process of claim 13, wherein forming the outer internal duct structure comprises folding at least one strip-shaped fabric having two longitudinal edges of the fabric about a centrally located longitudinal axis and abutting the longitudinal edges to define at least an outer longitudinal chamber.

15. 14. The process of claim 13, wherein forming the outer internal duct structure comprises folding at least two strip-shaped fabrics, each having two longitudinal edges of the fabric around a centrally located longitudinal axis, and abutting the longitudinal edges to define at least two outer longitudinal chambers.

16. 14. The process of claim 13, wherein the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inwardly of the outer longitudinal fabric chamber, has a burst strength of greater than about 60 psi.

17. 14. The process of claim 13, wherein only the inner longitudinal chamber has a burst strength of less than about 35 psi.

18. The process of claim 13 , wherein the inner longitudinal chamber is movable within the outer longitudinal fabric chamber.

19. 1. A process for forming a blowable flexible internal duct, comprising: forming an inner internal duct structure comprising at least one inner longitudinal chamber, said at least one inner longitudinal chamber comprising an inflatable tube; forming an outer internal duct structure having at least one outer longitudinal chamber and simultaneously inserting at least one inner longitudinal chamber into at least one of the outer longitudinal chambers, the inflatable tube having a wall thickness of less than about 0.5 mm; wherein only the inner longitudinal chamber has an air permeability of less than about 1 cfm, and only the outer longitudinal fabric chamber has an air permeability of greater than about 100 cfm, and the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inside the outer longitudinal fabric chamber, has an air permeability of less than about 1 cfm.

20. 20. The process of claim 19, wherein the outer longitudinal fabric chamber, together with an inner longitudinal chamber located inwardly of the outer longitudinal fabric chamber, has a burst strength of greater than about 60 psi.

21. 20. The process of claim 19, wherein only the inner longitudinal chamber has a burst strength of less than about 35 psi.

22. 20. The process of claim 19, wherein the inner longitudinal chamber fills at least about 60% of a cross-sectional area of ​​the outer longitudinal chamber.

23. 20. The process of claim 19, wherein the inner longitudinal chamber is configured to surround and carry at least one cable.

24. 20. The process of claim 19, wherein the inner longitudinal chamber is movable within the outer longitudinal fabric chamber.

Images