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Title:
POLYMERIC PRESSURE VESSEL HAVING MANIFOLD WITH INTEGRATED INLET VALVE
Document Type and Number:
WIPO Patent Application WO/2001/095969
Kind Code:
A1
Abstract:
A polymeric pressure vessel (40) for a container system for pressurized fluids includes two or more strands (120) of hollow polymeric chambers interconnected by polymeric conduit sections. Each strand is attached at an open end thereof to a manifold (118) having an inner plenum in pneumatic communication with the interior of each strand. An inlet valve (518) is integrally incorporated into the manifold to control flow into and out of the manifold and the strands of interconnected chambers attached thereto.

Inventors:
SANDERS STAN A
NNAJI BARTHOLOMEW O
DESAI SALIL
Application Number:
PCT/US2001/018884
Publication Date:
December 20, 2001
Filing Date:
June 13, 2001
Export Citation:
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Assignee:
MALLINCKRODT INC (US)
International Classes:
A62B7/02; F16L41/03; (IPC1-7): A61M16/00; A61G10/00; A62B7/00; F16K17/14; F16L33/00
Foreign References:
US4932403A1990-06-12
US4964405A1990-10-23
US6230737B12001-05-15
US4736969A1988-04-12
US2524052A1950-10-03
Attorney, Agent or Firm:
Repper, George R. (Figg Ernst & Manbeck, P.C. 1425 K Stree, N.W. Suite 800 Washington D.C., US)
Download PDF:
Claims:
CLAIMS
1. A container system for pressurized fluids comprising: two or more continuous strands of hollow polymeric chambers interconnected by polymeric conduit sections disposed between adjacent ones of said chambers; a manifold defining an inner plenum, wherein a first end of each of said strands is pneumatically sealed and a second end of each of said strands is connected to said manifold in pneumatic communication with said inner plenum; and an inlet valve disposed within said manifold, said inlet valve being constructed and arranged to permit fluid under pressure to be transferred through said inlet valve and into said inner plenum and said strands and to prevent fluid within said strands from escaping therefrom through said inlet valve.
2. The container system of claim 1, wherein said manifold comprises a main body, and wherein said inlet valve comprises a valve body and a valve seat, said valve body and said valve seat being disposed within said main body, said valve body being movable with respect to said valve seat between an engaged position preventing fluid flow through said inlet valve and a disengaged position permitting fluid flow through a gap between said valve body and said valve seat.
3. The container system of claim 2, wherein said inlet valve further comprises a spring disposed between a portion of said main body and a portion of said valve body for urging said valve body into the engaged position with respect to said valve seat.
4. The container system of claim 2, wherein said inlet valve further comprises a valve housing embedded into said main body, said valve body and said valve seat being disposed within said valve housing.
5. The container system of claim 1, further comprising: a mechanical fitting connected to an end of one or more of said strands of interconnected chambers, said mechanical fitting comprising a body portion with a projection extending therefrom and adapted to be inserted into an open end of said strand, said projection having barbs formed thereon constructed and arranged to permit said projection to be inserted into said strand but to resist removal of said projection from the strand; and a ferrule for securing said strand onto said projection, said ferrule being connected at one longitudinal end thereof to said body portion and arranged in an outwardly spaced coaxial relation with respect to said projection, said ferrule having a crimping portion constructed and arranged to be radially crimped onto a portion of said strand into which said projection is inserted to thereby compress the portion of said strand into said barbs to secure the conduit section onto said projection.
6. The container system of claim 5, wherein said body portion of said mechanical fitting includes a threaded collar adjacent said projection and said ferrule includes a threaded opening at the one longitudinal end thereof, wherein said ferrule is connected to said body portion by threading said threaded collar of said body portion into said threaded opening of said ferrule.
7. The container system of claim 5, wherein said body portion of said mechanical fitting includes threads constructed and arranged to engage mating threads formed on said manifold to permit said strand to be attached to said manifold via said mechanical fitting.
8. The container system of claim 1, wherein said oneway inlet valve comprises a pressure actuatable poppet valve.
Description:
POLYMERIC PRESSURE VESSEL HAVING MANIFOLD WITH INTEGRATED INLET VALVE Field of the Invention The present invention is directed to a container system for pressurized fluids that is lightweight and more resistant to explosive rupturing than prior art containers and thus can be adapted into embodiments that are portable to provide ambulatory supplies of fluid under pressure.

Background of the Invention There are many applications for a portable supply of fluid under pressure. For example, SCUBA divers and firefighters use portable, pressurized oxygen supplies. Commercial aircraft employ emergency oxygen delivery systems that are used during sudden and unexpected cabin depressurization. Military aircraft typically require supplemental oxygen supply systems as well.

Such systems are supplied by portable pressurized canisters. In the medical field, gas delivery systems are provided to administer medicinal gas, such as oxygen, to a patient undergoing respiratory therapy. Supplemental oxygen delivery systems are used by patients that benefit from receiving and breathing oxygen from an oxygen supply source to supplement atmospheric oxygen breathed by the patient. For such uses, a compact, portable supplemental oxygen delivery system is useful in a wide variety of contexts, including hospital, home care, and ambulatory settings.

High-pressure supplemental oxygen delivery systems typically include a cylinder or tank containing oxygen gas at a pressure of up to 3,000 psi. A pressure regulator is used in a high- pressure oxygen delivery system to"step down"the pressure of oxygen gas to a lower pressure (e. g., 20 to 50 psi) suitable for use in an oxygen delivery apparatus used by a person breathing the supplemental oxygen.

In supplemental oxygen delivery systems, and in other applications employing portable supplies of pressurized gas, containers used for the storage and use of compressed fluids, and particularly gases, generally take the form of cylindrical metal bottles that may be wound with reinforcing materials to withstand high fluid pressures. Such storage containers are expensive to manufacture, inherently heavy, bulky, inflexible, and prone to violent and explosive fragmentation upon rupture.

Container systems made from lightweight synthetic materials have been proposed.

Scholley, in U. S. Patent Nos. 4,932,403 ; 5,036,845; and 5,127,399, describes a flexible and portable container for compressed gases which comprises a series of elongated, substantially cylindrical chambers arranged in a parallel configuration and interconnected by narrow, bent conduits and attached to the back of a vest that can be worn by a person. The container includes a liner, which may be formed of a synthetic material such as nylon, polyethylene, polypropylene, polyurethane, tetrafluoroethylene, or polyester. The liner is covered with a high-strength reinforcing fiber, such as a high-strength braid or winding of a reinforcing material such as Kevlar aramid fiber, and a protective coating of a material, such as polyurethane, covers the reinforcing fiber. The design described in the Scholley patents suffers a number of shortcomings which makes it impractical for use as a container for fluids stored at the pressure levels typically seen in portable fluid delivery systems such as SCUBA gear, firefighter's oxygen systems, emergency oxygen systems, and medicinal oxygen systems. The elongated, generally cylindrical shape of the separate storage chambers does not provide an effective structure for containing highly-pressurized fluids. Moreover, the relatively large volume of the storage sections creates an unsafe system subject to possible violent rupture due to the kinetic energy of the relatively large volume of pressurized fluid stored in each chamber.

SUMMARY OF THE INVENTION In accordance with aspects of the present invention, a container system for pressurized fluids comprises two or more continuous strands of hollow polymeric chambers interconnected by polymeric conduit sections disposed between adjacent ones of the chambers, a manifold defining an inner plenum, and an inlet valve disposed within the manifold. A first end of each of the two or more continuous strands is pneumatically sealed and a second end of each of the two or more continuous strands is connected to the manifold in pneumatic communication with the inner plenum. The inlet valve permits fluid under pressure to be transferred through the inlet valve and into the inner plenum and the strands and prevents fluid within the strands from escaping therefrom through the inlet valve.

In accordance with a preferred embodiment of the invention, the manifold comprises a main body, and the inlet valve comprises a valve body and a valve seat. The valve body and the valve seat are disposed within the main body, and the valve body is movable with respect to the valve seat between an engaged position preventing fluid flow through the inlet valve and a

disengaged position permitting fluid flow through a gap between the valve body and the valve seat.

Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of the specification, and wherein like reference numerals designate corresponding parts in the various figures.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a broken side elevational view of a polymeric pressure vessel comprising a plurality of aligned, rigid, generally ellipsoidal chambers interconnected by a tubular core.

FIG. 2 is an enlarged horizontal sectional view taken along the line 2-2 in FIG. 1.

FIG. 2A is an enlarged horizontal sectional view taken along the line 2-2 in FIG. 1 showing an alternate embodiment.

FIG. 3 is a side elevational view of a portion of a container system of the present invention.

FIG. 4 is a partial longitudinal sectional view along line 4-4 in FIG. 3.

FIG. 5 shows a pressurized fluid pack employing a polymeric pressure vessel.

FIG. 6 is a longitudinal cross-section of a manifold for use in the pressurized fluid pack of FIG. 5.

FIG. 7 is a longitudinal cross-section of a second embodiment of a manifold, including an integral inlet valve, for use in the pressurized fluid pack of FIG. 5.

FIG. 8 is a partial, exploded view in longitudinal section of a system for securing a polymeric tube to a mechanical fitting.

DETAILED DESCRIPTION OF THE INVENTION With reference to the figures, exemplary embodiments of the invention will now be described. These embodiments illustrate principles of the invention and should not be construed as limiting the scope of the invention.

As shown in FIGS. 1 and 2, U. S. Patent No. 6,047,860 (the disclosure of which is hereby incorporated by reference) to Sanders, an inventor of the present invention, discloses a container system 10 for pressurized fluids including a plurality of form-retaining, generally ellipsoidal chambers C interconnected by a tubular core T. The tubular core extends through each of the plurality of chambers and is sealingly secured to each chamber. A plurality of longitudinally-

spaced apertures A are formed along the length of the tubular core, one such aperture being disposed in the interior space 20 of each of the interconnected chambers so as to permit infusion of fluid to the interior space 20 during filling and effusion of the fluid from the interior space 20 during fluid delivery or transfer to another container. The apertures are sized so as to control the rate of evacuation of pressurized fluid from the chambers. Accordingly, a low fluid evacuation rate can be achieved so as to avoid a large and potentially dangerous burst of kinetic energy should one or more of the chambers be punctured (i. e., penetrated by an outside force) or rupture.

The size of the apertures A will depend upon various parameters, such as the volume and viscosity of fluid being contained, the anticipated pressure range, and the desired flow rate. In general, smaller diameters will be selected for gasses as opposed to liquids. Thus, the aperture size may generally vary from about 0.010 to 0.125 inches. Although only a single aperture A is shown in FIG. 2, more than one aperture A can be formed in the tube T within the interior space 20 of the shell 24. In addition, each aperture A can be formed in only one side of the tube T, or the aperture A may extend through the tube T.

Referring to Fig. 2, each chamber C includes a generally ellipsoidal shell 24 molded of a suitable synthetic plastic material and having open front and rear ends 26 and 28. The diameters of the holes 26 and 28 are dimensioned so as to snugly receive the outside diameter of the tubular core T. The tubular core T is attached to the shells 24 so as to form a fluid tight seal therebetween. The tubular core T is preferably bonded to the shells 24 by means of light, thermal, or ultrasonic energy, including techniques such as, ultrasonic welding, radio frequency energy, vulcanization, or other thermal processes capable of achieving seamless circumferential welding. The shells 24 may be bonded to the tubular core T by suitable ultraviolet light-curable adhesives, such as 3311 and 3341 Light Cure Acrylic Adhesives available from Loctite Corporation, having authorized distributors throughout the world. The exterior of the shells 24 and the increments of tubular core T between such shells are pressure wrapped with suitable pressure resistant reinforcing filaments 30 to resist bursting of the shells and tubular core. A protective synthetic plastic coating 32 is applied to the exterior of the filament wrapped shells and tubular core T.

More particularly, the shells 24 may be either roto molded, blow molded, or injection molded of a synthetic plastic material such as TEFLON or fluorinated ethylene propylene.

Preferably, the tubular core T will be formed of the same material. The pressure resistant filaments 30 may be made of a carbon fiber, Kevlar or Nylon. The protective coating 32 may be made of urethane to protect the chambers and tubular core against abrasions, W rays, moisture,

or thermal elements. The assembly of a plurality of generally ellipsoidal chambers C and their supporting tubular core T can be made in continuous strands of desired length. In the context of the present disclosure, unless stated otherwise, the term"strand"will refer to a discrete length of interconnected chambers.

As shown in FIG. 2A, the tube T can be co-formed, such as by co-extrusion, along with shells 24'and tubular portions T'integrally formed with the shells 24'and which directly overlie the tube T between adjacent shells 24'. Furthermore, as also shown in FIG. 2A, more than one aperture A may be formed in the tube T within the interior 20 of the shell 24'. The co-formed assembly comprised of the shells 24', tubular portions T', and tube T can be wrapped with a layer of reinforcing filaments 30 and covered with a protective coating 32 as described above.

The inlet or front end of the tubular core T may be provided with a suitable threaded male fitting 34. The discharge or rear end of a tubular core T may be provided with a threaded female fitting 36. Such male and female fittings provide a pressure-type connection between contiguous strands of assemblies of chambers C interconnected by tubular cores T and provide a mechanism by which other components, such as valves or gauges, can be attached to the interconnected chambers. A suitable mechanism for attaching fittings, such as fittings 34 and 36, is described below.

A portion of an alternate pressure vessel is designated generally by reference number 40 in FIG. 3. The pressure vessel 40 includes a plurality of fluid storage chambers 50 having a preferred ellipsoidal shape and having hollow interiors 54. The individual chambers 50 are pneumatically interconnected with each other by connecting conduit sections 52 and 56 disposed between adjacent pairs of the chambers 50. Conduit sections 56 are generally longer than the conduit sections 52. The purpose of the differing lengths of the conduit sections 52 and 56 will be described in more detail below.

FIG. 4 shows an enlarged longitudinal section of a single hollow chamber 50 and portions of adjacent conduit sections 52 of the pressure vessel 40. The pressure vessel 40 preferably has a layered construction including polymeric hollow shells 42 with polymeric connecting conduits 44 extended from opposed open ends of the shells 42. The polymeric shells 42 and the polymeric connecting conduits 44 are preferably formed from a synthetic plastic material such as Teflon or fluorinated ethylene propylene and may be formed by any of a number of known plastic-forming techniques such as extrusion, roto molding, chain blow molding, or injection molding.

Materials used for forming the shells 42 and connecting conduits 44 are preferably moldable and exhibit high tensile strength and tear resistance. Most preferably, the polymeric hollow shells 42 and the polymeric connecting conduits 44 are formed from a thermoplastic polyurethane elastomer manufactured by Dow Plastics under the name Pellethane 2363-90AE, a thermoplastic polyurethane elastomer manufactured by the Bayer Corporation, Plastics Division under the name Texin 5286, a flexible polyester manufactured by Dupont under the name Hytrel@, or polyvinyl chloride from Teknor Apex.

In a preferred configuration, the volume of the hollow interior 54 of each chamber 50 is within a range of capacities configurable for different applications, with a most preferred volume of about thirty (30) milliliters. It is not necessary that each chamber have the same dimensions or have the same capacity. It has been determined that a pressure vessel 40 having a construction as will be described below will undergo a volume expansion of 7-10% when subjected to an internal pressure of 2000 psi. In a preferred configuration, the polymeric shells 42 each have a longitudinal length of about 3.0-3.5 inches, with a most preferred length of 3. 250-3.330 inches, and a maximum outside diameter of about 0.800 to 1.200 inches, with a most preferred diameter of 0.095-1.050 inches. The conduits 44 have an inside diameter D2 preferably ranging from 0.125-0.300 inches with a most preferred range of about 0.175-0.250 inches. The hollow shells 42 have a typical wall thickness ranging from 0.03 to 0.05 inches with a most preferred typical thickness of about 0.04 inches. The connecting conduits 44 have a wall thickness ranging from 0.03 to 0.10 inches and preferably have a typical wall thickness of about 0.040 inches, but, due to the differing amounts of expansion experienced in the hollow shells 42 and the conduits 44 during a blow molding forming process, the conduits 44 may actually have a typical wall thickness of about 0.088 inches.

The exterior surface of the polymeric hollow shells 42 and the polymeric connecting conduits 44 is preferably wrapped with a suitable reinforcing filament fiber 46. Filament layer 46 may be either a winding or a braid (preferably a triaxial braid pattern having a nominal braid angle of 75 degrees) and is preferably a high-strength aramid fiber material such as KevlarX (preferably 1420 denier fibers), carbon fibers, or nylon, with Kevlar being most preferred.

Other potentially suitable filament fiber material may include thin metal wire, glass, polyester, or graphite. The Kevlar winding layer has a preferred thickness of about 0.035 to 0.055 inches, with a thickness of about 0.045 inches being most preferred.

A protective coating 48 may be applied over the layer of filament fiber 46. The protective coating 48 protects the shells 42, conduits 44, and the filament fiber 46 from

abrasions, UV rays, thermal elements, or moisture. Protective coating 32 is preferably a sprayed- on synthetic plastic coating. Suitable materials include polyvinyl chloride and polyurethane. The protective coating 32 may be applied to the entire pressure vessel 40, or only to more vulnerable portions thereof. Alternatively, the protective coating 32 could be dispensed with altogether if the pressure vessel 40 is encased in a protective, moisture-impervious housing.

The inside diameter DI of the hollow shell 42 is preferably much greater than the inside diameter D of the conduit section 44, thereby defining a relatively discreet storage chamber within the hollow interior 54 of each polymeric shell 42. This serves as a mechanism for reducing the kinetic energy released upon the rupturing of one of the chambers 50 of the pressure vessel 40. That is, if one of the chambers 50 should rupture, the volume of pressurized fluid within that particular chamber would escape immediately. Pressurized fluid in the remaining chambers would also move toward the rupture, but the kinetic energy of the escape of the fluid in the remaining chambers would be regulated by the relatively narrow conduit sections 44 through which the fluid must flow on its way to the ruptured chamber. Accordingly, immediate release of the entire content of the pressure vessel is avoided.

Although the pressure chambers of the embodiments of FIGS. 1 and 3 are generally ellipsoidal in shape, spherical chambers are suitable as well, because such shapes are better suited than other shapes, such as cylinders, to withstand high internal pressures. Spherical chambers are not, however, as preferable as generally ellipsoidal chambers, because, the more rounded a surface is, the more difficult it is to apply a consistent winding of reinforcing filament fiber. Filament fibers, being applied with axial tension, are more prone to slipping on highly rounded, convex surfaces.

FIG. 5 shows a portable pressure pack 110 employing a pressure vessel as described above. The pressure pack 110 includes a pressure vessel comprised of a number of generally parallel strands 120 of hollow chambers 122 serially interconnected by interconnecting conduit sections 124. Each of the strands 120 has a closed end 126 at the endmost of its chambers 122 and an open terminal end 128 attached to a manifold 118. Each strand 120 may be connected to the manifold 118 by a threaded interconnection, a crimp, or a swage, or any other suitable means for connecting a high pressure polymeric tube to a rigid fitting. A fluid transfer control system 116 is attached to the manifold 118, and, in the illustrated embodiment, comprises a outlet valve/regulator 90 and an inlet valve (described below).

The hollow chambers of the pressure vessel shown in FIG. 5 can be of the type shown in FIGS. 2 and 2A having an internal perforated tubular core, or they can be of the type shown in FIG. 4 having no internal tubular core.

Details of an embodiment of the manifold 118 are shown in FIG. 6. The manifold 118 includes a body 130 that is generally cylindrical in shape and has formed therein an inner chamber 134 that defines the plenum. Body 130 is preferably formed from a light weight, high strength material, such as a high strength polycarbonate. Threaded radial openings 138 extend from the inner chamber 134 to an exterior surface of the body 130. An axial threaded opening 140 extends from the inner chamber 134 to an axial end surface of the body 130. The open end 128 of the topmost strand 120 (see FIG. 5) is coupled to the body 130 of the manifold 118 at the axial threaded opening 140, and the remaining strands 120 are connected at their respective open ends 128 to the body 130 at the radial threaded openings 138. Alternatively, the axial opening 140 could be omitted, and an additional radial opening could be provided so that all strands 120 could be attached to the manifold at radial openings, if sizing and other configurational envelope constraints permit. For attaching the respective strands 120 into the axial or radial openings of the manifold 118, an exteriorly threaded fitting is attached, for example by swaging, to the open ends of the respective strands.

A threaded axial opening 132 at an end of the body opposite the threaded axial opening 140 is configured to receive a one-way inlet valve, for example a poppet-style, pressure responsive valve or a pin valve. An outlet valve/regulator, such as regulator 90, can be coupled to the one-way inlet valve in a known manner to mechanically engage the poppet or pin mechanism of the inlet valve to thereby bypass the one-way inlet valve so that air exiting the pressure vessel is controlled by the outlet valve/regulator. Of course, the regulator must be removable so as to permit subsequent filling of the pressure vessel. Alternatively, if all strands of interconnected chambers of the pressure vessel can be attached at threaded radial openings formed in the body 130, and if sizing and configurational envelope restrictions permit, an outlet valve/regulator can be coupled into the body 130 at an axial end thereof opposite the inlet valve.

Such an arrangement, if possible, is advantageous, because the outlet valve/regulator need not be removed to permit filling of the pressure vessel.

An alternative manifold having a integrated one-way inlet valve is designated generally by reference number 518 in FIG. 7. The manifold 518 includes a main body 530 that is preferably of a generally cylindrical shape and is preferably formed from a high-strength polycarbonate material, having an inner chamber 534 defining a plenum within the body 530, and

a plurality of radial channels 538 and an axial channel 540 extending into the inner chamber 534.

As described above with respect to FIG. 6, strands of interconnected chambers forming a pressure vessel can be secured at their respective open ends to the radial openings 538 or the axial opening 540, for example, by a threaded connection.

A valve housing 541, preferably formed from a metallic material, is embedded into an axial end of the polycarbonate body 530. The valve body 541 has a generally hollow, cylindrical construction that is oriented coaxially with respect to the main body 530 and receives therein the components of the integrated one-way valve. More specifically, a coil spring 544 is received within the valve housing 541 and rests in an annular spring seat 536 formed in the body 530 below the housing 541. A valve body 546 is disposed within the housing 541 over the coil spring 544. The spring 544 extends into a spring recess 550 formed into one end of the valve body 546. A valve seat 552 is disposed within the valve housing 541 in abutting engagement with an annular shoulder 542 formed in the inner wall of the housing 541. Valve seat 552 has a generally hollow cylindrical construction with a radially extending flange at one end thereof defining an annular O-ring seat 560 on one side of the flange. An O-ring 554 extends around an upper cylindrical portion of the valve seat 552 and rests on the annular O-ring seat 560. A retaining ring 556 extends into an axial end of the housing 541 on top of the O-ring 554 so as to secure the O-ring 554 and the valve seat 552 within the housing 541.

At one end of the valve body 546, an annular sealing shoulder 548 extends around a cylindrical projection 547. The annular sealing shoulder 548 engages a conforming annular sealing shoulder 558 at an axial end of the valve seat 552, and the cylindrical projection 547 extends into the central axial opening of the valve seat 552. Under normal conditions, the coil spring 544 urges the valve body 546 into engagement with the valve seat 552, thereby creating a sealing engagement between the respective annular sealing shoulders 548 and 558. Under this condition, air cannot flow into or out of the manifold 518. With the application of sufficient inlet pressure acting on top of the cylindrical projection 547 (i. e., acting to the left in FIG. 7), the valve body 546 is moved to the left against the compressive force of the spring 544, thereby disengaging the valve body 546 and the valve seat 552. With the valve body 546 thus disengaged, fluid can flow through a gap between the valve body 546 and the valve seat 552 and into the manifold 518. When the source of inlet pressure is removed, the force of the spring 544, together with the force created by any pressure contained within the manifold 518, will urge the valve body 546 back into sealing engagement with the valve seat 552, to thereby retain fluid within the manifold 518 and the pressure vessel connected thereto.

As described above, the preferred integrated inlet valve is a pressure actuatable poppet- style valve. Consistent with the principles of the present invention, however, a mechanically- actuatable pin valve may be integrally incorporated into the manifold in substantially the same manner, as would be readily appreciated by one of ordinary skill in the art.

To permit use of the pressurized fluid within the pressure vessel and manifold 518, a regulator (not shown) can be operatively connected to the integrated one-way inlet valve in a known manner so as to push the valve body 546 out of engagement with the valve seat 552, to thereby bypass the inlet valve.

FIG. 8 shows a preferred arrangement for attaching a mechanical fitting 260 to a polymeric tube 262 in a manner that can withstand high pressures within the tube 262. Such fittings 260 can be attached to the ends of a continuous strand of serially connected hollow chambers for connecting inlet and outlet valves at the opposite ends. For example, fittings 34 and 36 shown in FIG. 1 could be attached in the manner to be described. The mechanical fitting 260 has a body portion, which, in the illustrated embodiment includes a threaded end 264 to which can be attached another component, such as a valve or a gauge, and a faceted portion 266 that can be engaged by a tool such as a wrench. End 264 is shown as an exteriorly threaded male connector portion, but could be an interiorly threaded female connector portion. An exteriorly threaded collar 268 extends to the right of the faceted portion 266. An inserting projection 270 extends from the threaded collar 268 and has formed thereon a series of barbs 272 of the "Christmas tree"or corrugated type that, due to the angle of each of the barbs 272, permits the projection 270 to be inserted into the polymeric tube 262, as shown, but resists removal of the projection 270 from the polymeric tube 262. A channel 274 extends through the entire mechanical fitting 260 to permit fluid transfer communication through the fitting 260 into a pressure vessel.

A connecting ferrule 280 has a generally hollow, cylindrical shape and has an interiorly threaded opening 282 formed at one end thereof. The remainder of the ferrule extending to the right of the threaded opening 282 is a crimping portion 286. The crimping portion 286 has internally-formed ridges 288 and grooves 284. The inside diameter of the ridges 288 in an uncrimped ferrule 280 is preferably greater than the outside diameter of the polymeric tube 262 to permit the uncrimped ferrule to be installed over the tube 262.

Attachment of the fitting 260 to the tube 262 is affected by first screwing the threaded collar 268 into the threaded opening 282 of the ferrule 280. Alternatively, the ferrule 280 can be connected to the fitting 260 by other means. For example, the ferrule 280 may be secured to the

fitting 260 by a twist and lock arrangement or by welding (or soldering or brazing) the ferrule 280 to the fitting 260. The polymeric tube 262 is then inserted over the inserting projection 270 and into a space between the crimping portion 286 and the inserting projection 270. The crimping portion 286 is then crimped, or swaged, radially inwardly in a known manner to thereby urge the barbs 272 and the ridges 288 and grooves 284 into locking deforming engagement with the tube 262. Accordingly, the tube 262 is securely held to the fitting 260 by both the frictional engagement of the tube 262 with the barbs 272 of the inserting projection 270 as well as the frictional engagement of the tube 262 with the grooves 284 and ridges 288 of the ferrule 280, which itself is secured to the fitting 260, e. g., by threaded engagement of the threaded collar 268 with the threaded opening 282.

A connecting arrangement of the type shown in FIG. 8 could also be used, for example, for attaching the strands of interconnected chambers 120 to the connecting nipples 138 and 140 of the manifold 118 of FIG. 5.

While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but, on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Thus, it is to be understood that variations in the particular parameters used in defining the present invention can be made without departing from the novel aspects of this invention as defined in the following claims.