Breathing apparatus, pressure vessel and associated manufacturing method

Abstract

A breathing apparatus including a pressure vessel is disclosed. The pressure vessel may include a composite shell formed from a plurality of fibers and a matrix comprising a resin material and graphene particles. The pressure vessel may include at least one permeation barrier layer including graphene particles or graphene nanoparticles disposed on an outer surface of the structural shell or an outer surface of the liner. A manufacturing method for the pressure vessel is also disclosed.

Description

Technical Field

[0001] The present disclosure relates to a breathing device, a pressure vessel, and related manufacturing methods. In particular, the present disclosure may relate to a breathing device having a pressure vessel with reduced permeability to chemical, biological, radiological, and nuclear (CBRN) contaminants and improved mechanical properties. Background Art

[0002] Pressure vessels are used with breathing apparatus to store clean breathing air for the user to breathe when they enter an environment where the surrounding gas is not breathable, such as in fires and contaminated areas.

[0003] When using breathing apparatus in environments due to the presence of chemical, biological, radiological and / or nuclear (CBRN) contaminants, it is important that these contaminants are not inhaled by the user as this could be fatal. For canisters with metal liners (Type III), the liner inherently prevents CBRN from penetrating the canister through the canister wall.

[0004] However, for newer tank designs that may have a polymer liner (Type IV) or no liner (Type V), the lack of a metal barrier increases the risk of CBRN contamination inward through the tank wall. Similarly, outward permeation of breathable air through the tank wall to the outside of the tank may also occur.

[0005] Furthermore, the absence of a metal liner may reduce the overall mechanical properties (eg, impact resistance) of a Type IV or Type V tank.

[0006] Therefore, there is a need for improvements in the art of pressure vessels for breathing apparatus. Summary of the invention

[0007] According to one aspect, a breathing apparatus is provided. The breathing apparatus may include a pressure vessel manufactured according to any other aspect and / or may include a pressure vessel according to any other aspect. This aspect may form part of any other aspect and / or be used in combination with any other aspect.

[0008] According to one aspect, a pressure vessel, such as for use in a breathing apparatus, is provided. The pressure vessel may be a composite pressure vessel. The pressure vessel may include a composite shell, such as a fiber reinforced polymer composite shell. The composite shell may be formed from a plurality of fibers and a matrix including a resin material. The composite shell may include graphene particles, such as graphene sheets. The graphene sheets may form a graphene layer.

[0009] The pressure vessel may be a breathing air container. The pressure vessel may be used for a SCBA (self-contained breathing apparatus). The pressure vessel may be used for a CCBA (closed circuit breathing apparatus). The graphene particles may be in the resin material, for example dispersed in the resin material. This aspect may form part of any other aspect and / or be used in combination with any other aspect.

[0010] According to one aspect, a pressure vessel for a breathing apparatus is provided, the pressure vessel comprising a fiber reinforced polymer composite shell having graphene sheets.

[0011] The pressure vessel may also include a liner, for example, within the composite shell (e.g., the container may be a Type IV tank). The liner may be a non-metallic liner, such as a plastic or polymer liner. The composite shell may encapsulate the liner, for example, to protect or increase the strength and / or structural integrity of the liner. Alternatively, the pressure vessel may not include a liner (e.g., the container may be a Type V tank).

[0012] Fiber reinforced polymer composites may include fiber reinforcement in a polymer matrix. The fiber reinforcement may include, for example, a plurality of fibers in bundles.

[0013] The fiber reinforcement may include a plurality of fiber layers (eg, two or more fiber layers). Each fiber layer may be a layer of fiber bundles. The fiber reinforcement may include a first fiber layer. The fiber reinforcement may include a second fiber layer.

[0014] The first fiber layer may include fibers wound in a first orientation (e.g., hoop-wound, polar-wound, or helically wound). The second fiber layer may include fibers wound in a second orientation (e.g., hoop-wound, polar-wound, or helically wound). The first orientation may be different from the second orientation.

[0015] The composite material may include a plurality of graphene layers (e.g., multiple graphene sheets). The or each graphene layer (e.g., graphene sheet layer) may be disposed within a matrix (e.g., encapsulated by a matrix). The graphene sheet layer may not include other forms of graphene. The graphene sheet layer may additionally include a matrix, such that adjacent graphene sheets within a layer may be separated by the matrix if not in contact.

[0016] The graphene layer may be disposed adjacent to the fiber layer. The graphene layer may be disposed between the liner and the fiber reinforcement (e.g., the first layer of fiber reinforcement). The liner may be spaced apart from the fiber reinforcement (e.g., the first layer of fiber reinforcement) by the graphene layer.

[0017] The first fiber layer and the second fiber layer may be separated by a graphene layer. The graphene sheet may be formed or constructed in at least one intermediate layer between the two fiber layers. An intermediate layer of graphene sheets may be formed between each pair of adjacent fiber layers. The housing may include a plurality of alternating fiber layers and graphene layers. Continuous fiber layers may be wound in different orientations.

[0018] The graphene sheets may be provided in the form of layers (e.g., only in the form of layers). The graphene sheets may be unevenly distributed throughout the matrix. The concentration of graphene throughout the shell may form a rectangular wave. The graphene layers may be separated by layers without graphene sheets. The graphene sheets may be provided in substantially discrete and / or discontinuous layers. The layers may be spaced apart along the thickness or radial direction of the pressure vessel wall or shell. The graphene sheets may not be dispersed within the fiber layers. The graphene sheets may not exist between fibers or fiber bundles in the same orientation (e.g., within the same fiber layer). The graphene sheets or layers may only exist between layers of fiber bundles oriented or wound in different directions.

[0019] The composite shell may include a plurality of layers (eg, concentric layers and / or stacked layers), including a first fiber layer and a first graphene layer. The plurality of layers may further include a second fiber layer and / or a second graphene layer.

[0020] Within the or each graphene layer, the graphene sheets may be generally aligned (e.g., substantially aligned), generally coplanar (e.g., substantially coplanar) and / or generally parallel (e.g., substantially parallel) to each other. The graphene sheets may be generally parallel (e.g., substantially parallel to) a local circumferential surface of the can. For example, the graphene sheets may be oriented substantially perpendicular to a local radius or thickness direction of the container (which may be generally cylindrical with hemispherical ends). Thus, the graphene sheets may be oriented substantially perpendicular to a local diffusion direction through the housing.

[0021] The or each graphene layer may comprise graphene sheets generally oriented at small angles to each other and / or to a local circumferential surface of the container. For example, the graphene sheets may generally be at an angle of no more than 45 degrees, preferably no more than 30 degrees, most preferably no more than 15 degrees to each other and / or to a local circumferential surface of the container.

[0022] The reduced CBRN permeability of the or each graphene layer may be formed by the combined properties of a large number of graphene sheets. For example, each graphene sheet individually may be impermeable to CBRN contaminants, so that a large number of sheets in the layer may form a tortuous diffusion path for CBRN contaminants. There may be gaps and discontinuities between adjacent graphene sheets within a layer. For example, the layer may not include a continuous sheet or foil of graphene. However, the or each graphene layer may provide a tortuous path through the container wall so as to inhibit inward penetration of CBRN agents and / or outward penetration of respiratory gases.

[0023] The graphene sheets may thereby form one or more permeation barrier layers within the composite shell. The one or more permeation barrier layers may be organized as intermediate layers between fiber layers. The pressure vessel may thereby include a permeation barrier layer comprising aggregated graphene sheets.

[0024] The or each graphene sheet may extend around the tank (e.g., continuously around the tank). For example, a fiber bundle (e.g., pre-impregnated or wet wound) may be wound around the entire tank in a first orientation such that a matrix coating (including a graphene sheet) formed on a surface of a first segment of the fiber bundle may be placed adjacent to a matrix coating (including a graphene sheet) on a surface of a second segment of the fiber bundle. The matrix coatings may then merge with each other (e.g., during curing) to form a single layer of graphene sheet.

[0025] The graphene sheets may initially be randomly oriented within the liquid matrix. However, as the liquid matrix impregnates the fiber reinforcement, wicking of the matrix into the fiber reinforcement may serve to increase alignment between the graphene sheets.

[0026] The sheets may have a thickness, an in-plane minor axis, and an in-plane major axis. The thickness of each sheet may be substantially smaller than the in-plane dimension. The thickness of the sheet may be at least one order of magnitude smaller than the in-plane dimension. The sheet may be substantially planar.

[0027] The graphene sheet may have an in-plane major axis dimension and / or an in-plane minor axis dimension that is greater than the fiber diameter of the fiber reinforcement. The major axis dimension and / or the minor axis dimension of the graphene sheet may be at least twice (optionally three times) the fiber diameter. The graphene sheet may have a major axis dimension of about 8-50 microns. The graphene sheet may have a major axis dimension of about 20 microns. Each fiber filament of the fiber reinforcement may have a uniform diameter. The fiber diameter may be about 3-10 microns. It should be understood that the graphene sheet may not have a precise or regular shape. The major axis dimension of the graphene sheet may be the largest dimension that can be measured across the sheet.

[0028] The graphene sheet may include a single-layer graphene sheet, a few-layer graphene sheet (e.g., 2-5 layers), or a multi-layer sheet (e.g., up to 10 layers). The graphene may include functionalized graphene. For example, the graphene may include graphene oxide or another functional group.

[0029] The fiber reinforcement may include (e.g., consist essentially of) carbon fibers and / or aramid fibers. The matrix may include a thermoplastic matrix (e.g., an acrylic, nylon, polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyetherimide, polycarbonate, or polypropylene matrix). The matrix may include a thermosetting matrix (e.g., an epoxy, polyester, vinyl ester, phenolic resin, bismaleimide, polyimide).

[0030] The matrix can include up to about 10% by weight of graphene sheets. Alternatively, the matrix can include up to about 8% by weight of graphene particles. In particular, the matrix can include 0.1% to 2% by weight of graphene particles, or in a particular embodiment, 1% by weight of graphene particles. The matrix can include at least 0.1 wt% of graphene sheets. Since gravity is assumed to be constant, mass proportions and weight proportions can be interchanged. The composite material can include 60-65 wt% of fiber reinforcement and 35-40 wt% of the matrix, of which 0.1-10 wt% can be graphene sheets.

[0031] This aspect may form part of and / or be used in combination with any other aspect.

[0032] According to one aspect, a method of manufacturing a pressure vessel, for example for a breathing apparatus, is provided. The method may include providing a matrix (e.g., a polymer matrix such as a resin). The matrix may include, for example, graphene sheets in a resin material. The method may include impregnating a plurality of fibers (e.g., fiber reinforcements) with the matrix. The method may further include curing the matrix and fibers to form a shell of the pressure vessel. This aspect may form part of any other aspect and / or be used in combination with any other aspect.

[0033] According to one aspect, there is provided a method of manufacturing a pressure vessel for a breathing apparatus, the method comprising: providing a polymer matrix having at least 0.1 wt % graphene sheets; impregnating a fiber reinforcement with the matrix.

[0034] The fibers may be pre-impregnated with a matrix. In other words, the fibers may be pre-impregnated fibers. Pre-impregnated fibers are typically chemically or thermally "B-staged" with a matrix to partially cure the matrix (e.g., with heat or UV) and then wound onto a bobbin. The pre-impregnated fibers may then be unwound from the bobbin to be used. The method may include pre-impregnating a fiber reinforcement. The method may also include B-staging the fiber reinforcement.

[0035] The graphene sheets may be suspended or incorporated into the matrix. The graphene sheets may be dispersed (e.g., uniformly or evenly, such as by stirring) throughout the matrix. The graphene sheets may be added to the matrix (e.g., resin) prior to impregnation into the fiber reinforcement.

[0036] The shell may be wet wound. The impregnation step may comprise impregnating the fibres by drawing the fibres through a matrix, for example through a matrix bath. The method may comprise wet winding the fibre reinforcement.

[0037] The plurality of fibers may be wound around a mat or mandrel. Winding may occur prior to curing. The winding may include spiral, annular, polar and / or cylindrical windings. End caps may be provided on the mat prior to winding.

[0038] If pre-impregnated fibers are used, these fibers can be directly applied to the mat from a spool. This can have the advantage of reducing the number of manufacturing steps required when manufacturing the pressure vessel. If non-pre-impregnated fibers are used, the impregnation step can be performed between unwinding the fibers from the spool and winding the fibers onto the mat.

[0039] Curing may include flowing the matrix to form one or more graphene layers within the housing. The matrix (optionally the resin material of the matrix) may flow during curing to align the graphene particles. The resin may solidify during curing to form a rigid matrix that fixes the graphene particles in place.

[0040] The method may include winding the fiber reinforcement around a mat or mandrel in a first orientation to form a first layer of fiber reinforcement. The method may include winding the fiber reinforcement around a mat or mandrel in a second orientation to form a second layer of fiber reinforcement. The second orientation may be different from the first orientation.

[0041] This aspect may form part of and / or be used in combination with any other aspect.

[0042] According to one aspect, a pressure vessel for a breathing apparatus is provided, comprising a structural shell and a liner. The pressure vessel further comprises at least one permeation barrier layer, the permeation barrier layer comprising a graphene sheet. The permeation barrier layer may be disposed on an outer surface of the structural shell or on an outer surface of the liner. The structural shell may be a composite shell. The composite shell may include fibers and a matrix.

[0043] This aspect may form part of and / or be used in combination with any other aspect.

[0044] According to one aspect, a method of manufacturing a pressure vessel for a breathing apparatus is provided, the method comprising: providing a mold for forming a liner of the pressure vessel; coating at least a portion of the mold with graphene microparticles and / or graphene nanoparticles (e.g., graphene sheets); and then introducing a liner material into the mold to form the liner, such that the liner includes graphene microparticles or graphene nanoparticles on an outer surface thereof.

[0045] The graphene microparticles and / or graphene nanoparticles may be suspended or incorporated into the resin or fluid used to coat the mold.

[0046] The mould may comprise an internal volume defining a shape for the cushion. The internal volume may be defined by an inner surface of the mould. The graphene particles may be applied to a portion of the inner surface of the mould.

[0047] This aspect may form part of and / or be used in combination with any other aspect.

[0048] Those skilled in the art will appreciate that, except mutually exclusive situations, the features described in any one of the above aspects can be applied to any other aspects with necessary changes. In addition, except mutually exclusive situations, any feature described herein can be applied to any aspect and / or combined with any other feature described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0050] Figure 1 is a cross-sectional side view of a pressure vessel for a breathing apparatus;

[0051] Figure 2 yes Figure 1 Detailed cross-sectional view of the pressure vessel;

[0052] Figure 3 is a schematic diagram of the structure of the shell of the pressure vessel;

[0053] Figure 4 is a schematic diagram of a graphene sheet for use in a pressure vessel or a method for manufacturing the same;

[0054] Figure 5 A method for manufacturing a pressure vessel is schematically illustrated;

[0055] Figure 6 An apparatus for making pre-impregnated fiber bundles is shown;

[0056] Figure 7 An apparatus for making a pressure vessel from pre-impregnated fiber bundles is shown;

[0057] Figure 8An apparatus for manufacturing a pressure vessel using wet winding of fiber bundles is shown;

[0058] Fig. 9 shows a cross-sectional side view of an alternative pressure vessel for a breathing apparatus;

[0059] Fig.10 yes Fig. 9 A detailed cross-sectional view of the pressure vessel; and

[0060] Fig.11 A method for producing a pressure vessel is schematically shown. DETAILED DESCRIPTION

[0061] Figure 1 A cross-sectional view of a pressure vessel 100 for a breathing apparatus (not shown) is schematically shown. In this embodiment, the pressure vessel 100 is a breathing air container. The breathing apparatus may be a self-contained breathing apparatus (SCBA) or a closed circuit breathing apparatus (CCBA).

[0062] The pressure vessel 100 includes a hollow, generally cylindrical body with hemispherical ends. In other embodiments, the pressure vessel 100 may have a different shape, such as a quasi-spherical end.

[0063] The pressure vessel 100 includes a composite shell 102 and a liner 104, which define an interior volume or chamber V. In this embodiment, the liner 104 is enclosed by the composite shell 102. The liner 104 is a plastic liner, but in other embodiments may be made of other materials, such as metal (e.g., aluminum, steel, or alloys). For example, the liner may be made of PA6 nylon, polyethylene terephthalate (PET), or high-density polyethylene (HDPE), among other plastics, depending on the requirements and the manufacturing process to be used.

[0064] The liner 104 performs the primary function of providing a barrier to retain the fluid within the pressure vessel 100, and the composite shell 102 encapsulates the liner 104 to protect the liner 104 and increase the strength and structural integrity of the vessel 100. The liner 104 may be substantially impermeable to the fluids it is designed to contain (e.g., breathing air), but may not completely prevent penetration by other substances (e.g., CBRN contaminants).

[0065] The liner 104 has a neck 106 that protrudes from the composite shell 102 at one hemispherical end of the pressure vessel 100. The neck 106 can be connected to a breathing apparatus so that the contents of the pressure vessel can be supplied to the breathing apparatus. The neck 106 can be formed as a separate piece made of a different material than the rest of the liner 104. For example, the neck 106 can be constructed of metal, and the rest of the liner 104 can be made of plastic and blow molded around the neck 106 to connect the two parts. In some embodiments, additional fittings can be provided at the opposite hemispherical ends, for example to allow positioning and / or clamping of the liner 104 and container 100 when they are manufactured. In other embodiments, the neck or portion thereof can be provided as a separate component that is installed after manufacture of the liner and / or shell.

[0066] Now go to Figure 2 , a detailed view of a cross section of the pressure vessel 100 is shown. Figure 2 Shows Figure 1 An exemplary portion of the pressure vessel 100 is shown at X in FIG. Figure 2 , the layering and construction of the composite shell 102 and liner 104 can be more clearly seen.

[0067] Referring first to the liner 104, it can be seen that the liner 104 is a substantially uniform layer of material, in this case plastic. The liner 104 is arranged to form the innermost surface of the pressure vessel 100 facing the interior volume V.

[0068] The composite shell 102 covers the liner 104 and, in this embodiment, forms the outermost surface of the pressure vessel 100 that is exposed to the external environment E. In other embodiments, the shell 102 itself may be covered by another layer or layers of material or composite material, such as another protective layer and / or decorative layer, which would then form the outermost surface of the pressure vessel 100.

[0069] If available Figure 2 As understood in the foregoing, the composite shell 102 includes a plurality of components. Typically, the composite shell 102 is formed by a plurality of fibers 108 and a matrix 110. The matrix 110 substantially encapsulates the fibers 108 and itself includes two main parts: a resin material 112 and graphene particles 114. The matrix may include up to about 10% by weight of graphene particles. In some embodiments, the matrix may include up to about 8% by weight of graphene particles. In particular, the matrix may include 0.1% to 2% by weight of graphene particles, or in a particular embodiment, 1% by weight of graphene particles. The matrix may include a resin, such as an epoxy resin, in which graphene particles are distributed. The composite material may include 60-65 wt% of fiber reinforcement and 35-40 wt% of the matrix, of which 0.1-10 wt% may be graphene sheets.

[0070] During manufacturing, as will be described in more detail below, the resin material 112 is initially in liquid form, and the graphene particles 114 are substantially uniformly dispersed within the resin material 112. This liquid form of the matrix 110 is coated on the fibers 108, and the fibers 108 are wound on the liner 104 in layers. After being wound on the liner 104, the matrix 110 is cured so that the resin material 112 is hardened and the graphene particles 114 are arranged in its layer. Therefore, during curing, the matrix can flow so as to order the graphene particles within the shell.

[0071] In this schematic exemplary illustration of the pressure vessel 100, two fiber layers 116 and 118 are shown. It should be understood that in other embodiments, more fiber layers may be provided.

[0072] It can also be understood in this embodiment that the graphene particles 114 in the matrix 110 form alternating layers 120a, 120b and 120c with the fiber layers 116, 118. One of the graphene layers 120b forms an intermediate layer between the two fiber layers 116, 118. In the case of providing more than two fiber layers, an intermediate layer of graphene particles can be formed between each pair of fiber layers. More generally, the housing 102 can include a plurality of alternating fiber layers and graphene layers.

[0073] The inner fiber layer 116 is wound as a "ring" wound layer. Prior to winding, the fibers are organized into bundles, which are dense discrete bundles of fibers 108. The bundles are generally substantially flat in cross-section, having a width of 1-5 mm and a thickness of less than 1 mm. f It will be appreciated that the fiber bundles are extremely densely packed so that each bundle can be handled like an elongated ribbon. It will also be appreciated that after the shell 102 is cured, the discrete bundles of fibers 108 may no longer be discernible because the matrix and fibers become homogenized.

[0074] The beam is wrapped around the cylindrical portion of the pressure vessel 100 between the hemispherical ends at an angle as close to perpendicular as possible to the axial direction of the pressure vessel 100, typically at an angle of about 87 degrees to the axial direction. Figure 1 and Figure 2 When viewed in a cross-sectional plane along the axis of the container 100, the fiber bundle is viewed substantially perpendicular to its length and appears substantially circular in cross section. When the container 100 is pressurized, the annular layer 116 primarily resists radial expansion of the liner 104.

[0075] The outer fiber layer 118 is wound as a "helical" wound layer. The bundle is wound along the entire pressure vessel 100 at an angle to the axial direction of the vessel, typically about 10-15 degrees thereto, and is wound on a hemispherical end. Figure 1 and Figure 2 When viewed in a cross-sectional plane along the axis of the container 100, the fiber is viewed obliquely relative to its length and appears as an elongated ellipse in cross section. When the container 100 is pressurized, the helical layer 116 primarily resists axial expansion of the liner 104.

[0076] Alternating annular fiber layers and spiral fiber layers may be provided, or a plurality of adjacent annular layers or spiral layers may be provided, or any combination thereof. In some embodiments, high angle spiral winding or "knuckle" winding may also be used, having fibers wound at about 55-70 degrees relative to the axial direction of the vessel.

[0077] The resin material 112 coats and encapsulates the fibers 108 and the graphene particles 114. The resin material 112 fills the gaps between the fibers 108 and the particles 114.

[0078] The graphene particles 114 reduce the permeability of the composite shell 102 to harmful substances (e.g., CBRN contaminants), and thus inhibit these substances from entering the internal volume V of the pressure vessel 100. Therefore, the pressure vessel according to the present disclosure can improve the safety of breathing equipment used in a CBRN contaminated environment. Similarly, the graphene particles 114 inhibit the exhaust of breathing air from the internal volume V.

[0079] refer to Figure 3 and Figure 4 , the graphene particles 114 and their configuration in the composite material layer will be described in more detail.

[0080] The graphene particles 114 are graphene sheets 114. The sheets are substantially in the form of a plane. An exemplary graphene sheet 114e is Figure 4 The sheet 114e has a thickness (which is the entry / exit Figure 4 dimensions), for example, the thickness of sheet 114e is at least one order of magnitude smaller than the width and height of the sheet.

[0081] Each graphene sheet 114 (eg, exemplary sheet 114e) has a major axis d that spans a maximum distance across the sheet 114. max Each sheet 114 also has a longitudinal axis d max The short axis d across the sheet 114 in the same plane min In this embodiment, the minor axis d min is in the plane of the sheet 114 perpendicular to the major axis d maxThe maximum distance across the sheet 114. It should be understood that the major axis d max and the minor axis d min are the two largest perpendicular dimensions spanning the plane of the flake 114. It should also be understood that a graphene particle or flake may not have a precise or regular shape.

[0082] Reference now Figure 3 , the layering of graphene sheets 114 within composite housing 102 will be described.

[0083] The fibers 108 in the housing are formed into bundles that may each include several thousand fibers, typically 3,000-100,000 for carbon fibers, or less than 3,000 fibers for other fiber types (e.g., aramid). Here, for simplicity, only a small number of fibers 108 are shown. Typically, each fiber 108 is substantially a fiber having a diameter d f It will be appreciated that the fiber bundles are extremely densely packed so that each bundle includes a plurality of fibers that can be stacked on top of each other to form a plurality of fibers (i.e., a thickness of d f multiples of) layers.

[0084] The graphene sheet 114 is specifically selected so that its minor axis d min Greater than the diameter d of the fiber 108 f , and preferably 2 times or more the diameter of the fiber 108. Therefore, when the fibers 108 are tightly wound into layers, as Figure 3 As schematically shown in FIG. 1 , the graphene sheets 114 cannot fit into the gaps between the fibers 108 and overlap each other to form graphene sheets, such as Figure 2 The layers 120a, 120b, 120c in the embodiment are arranged adjacent to the fiber layer 108. Figure 3 , the graphene sheet 114 is shown only on one side of the fiber 108, but it may be present on both sides of the fiber, meaning that a graphene layer may be formed above and below each fiber layer.

[0085] Furthermore, during curing of the resin 112 , pressure applied to the housing 102 may cause any sheets 114 that are trapped between the fibers 108 or that are not substantially aligned with other sheets 114 to become aligned in layers.

[0086] The graphene sheets 114 within each layer 120 a , 120 b , 120 c are generally oriented at a low angle (eg, approximately 15 degrees) to each other, and are further oriented generally perpendicular to the diffusion direction across the housing 102 .

[0087] It will be appreciated that the size of the graphene particles will depend on the size of the fibers in the shell. In one particular embodiment, the graphene particles may have a minor axis of about 8-50 microns, and optionally about 20 microns, and the fibers may have a diameter of about 3-10 microns, meaning that a single graphene sheet may typically cover about 2-5 fibers.

[0088] The graphene particles 114 in one or more layers 120 are substantially impermeable to harmful CBRN agents, meaning that CBRN agents can only penetrate around the graphene particles 114 in the resin material 112. Because the graphene particles 114 are substantially overlapped in the layers 120, the available permeation paths for CBRN agents through each graphene layer 120 are highly tortuous, such that permeation through the composite shell 102 as a whole is substantially inhibited or even eliminated.

[0089] It will therefore be appreciated that in this embodiment the graphene particle layer 120 is a permeation barrier, in particular a CBRN permeation barrier.

[0090] Now go to Figures 5 to 8 , methods of manufacturing pressure vessels for breathing apparatus will now be discussed.

[0091] on the whole, Figure 5 A method 200 of making a pressure vessel for a breathing apparatus is shown, comprising: providing a polymer matrix having at least 0.1 wt % graphene sheets; and impregnating a fiber reinforcement with the matrix.

[0092] exist Figure 5 In the present invention, the first box 202 represents providing a polymer matrix having at least 0.1 wt% graphene sheets. Box 204 represents impregnating a fiber reinforcement with the matrix. Box 206 represents winding the impregnated fibers onto a mat, and box 208 represents curing the matrix and fibers to form a shell of a pressure vessel. Each of these processes will now be described in more detail.

[0093] exist Figure 6 , an apparatus 300 for forming pre-impregnated or "prepreg" fiber bundles is shown.

[0094] One or more fiber bundle spools 302 are provided, and a fiber bundle 306 is drawn from each spool 302. A bath 308 of a liquid matrix 310 is provided, which has a roller 312 partially immersed in the liquid matrix 310. As described above, the matrix 310 includes graphene particles, in particular graphene sheets. This is equivalent to Figure 5 Block 202. A stirring method may be used to ensure that the graphene particles are dispersed within the matrix 310 and / or to ensure that the matrix 310 is applied to the beam 306 consistently.

[0095] The roller 312 is rotated so that it provides a continuous matrix-coated surface 314 over which each fiber bundle 306 is drawn so as to impregnate the fiber bundle 306 with the matrix including the graphene sheets so as to provide one or more impregnated fiber bundles 306a. In other embodiments, the fiber bundles may be pulled directly through the matrix bath 308 (i.e., immersed in the matrix bath 308). A stirring method may be used to ensure that the graphene sheets are dispersed in the matrix and to ensure uniform coverage of the matrix on the fiber bundles.

[0096] After impregnation with the liquid matrix, in this embodiment, each impregnated fiber bundle 306a is subjected to a "B-staging" process by a curing device 316. During B-staging, the matrix 310 is partially cured so that the matrix 310 remains on the fiber bundle for transportation to another destination. It should be understood that for some matrix types, B-staging may not be required.

[0097] If B-staging is used, after B-staging, the fiber tow is now a pre-impregnated fiber tow 306, or "tow prepreg." The pre-impregnated fiber tow 306b is then wound onto a pre-preg spool 318 for storage and shipping.

[0098] refer to Figure 5 In this embodiment, impregnation of the fibers 204 thus includes two steps: impregnating the fibers, represented by box 210 , and forming pre-impregnated fibers (eg, by optional B-staging and rewinding), represented by box 212 .

[0099] Figure 7 An apparatus 400 for manufacturing a pressure vessel is shown which utilizes pre-impregnated fibers, such as those made of Figure 6 Those pre-impregnated fibers manufactured by the apparatus 300.

[0100] One or more pre-impregnated fiber tows ("tow prepregs") 402 are provided on a spool 404. It will be appreciated that in some embodiments only one fiber and spool may be used.

[0101] The bundle prepreg 402 is fed to a winding apparatus 406 including one or more winding heads 408. In this embodiment, for simplicity, only one winding head 408 is shown. In other embodiments, there may be multiple winding heads, such as a winding head for each bundle prepreg. The winding apparatus 406 is configured to wind the bundle prepreg 402 onto a mat 410 using one (or more) winding heads 408. Thus, by moving the winding head 408 relative to the mat 410, the winding apparatus 406 forms one or more fiber layers 412 on the mat 410. The winding apparatus may apply the bundle prepreg 402 as a spiral winding and / or a cylindrical winding. The fibers are wound onto the mat by the winding apparatus. Figure 5 The box 206 in FIG.

[0102] Finally, after winding (or other means of applying the fibers and matrix to the liner), the liner 410 covered by the fiber layer 412 is cured to harden the fibers and their associated matrix into the shell of the pressure vessel, such as by Figure 5 As represented by block 208 .

[0103] Figure 8 An alternative apparatus 400 for making a pressure vessel is shown. In this case, the apparatus 400 uses "wet winding" of fibers.

[0104] A plurality of fiber bundle spools 502 are provided. In some embodiments, the fiber spools may dispense a single dry fiber for a "filament winding" process, but in this embodiment, a "dry" fiber bundle 504 is unwound from the spool 502.

[0105] A bath 506 of a liquid matrix 508 is provided. The matrix 508 comprises graphene particles, in particular graphene sheets. This corresponds to Figure 5 Block 202. A stirring method may be used to ensure that the matrix 508 is applied to the beam consistently and / or to ensure that the graphene sheets are dispersed within the matrix.

[0106] The apparatus 500 is configured to draw (ie, immerse) a fiber bundle 504 through a matrix bath 506, thereby impregnating the fibers with a matrix comprising graphene sheets, thereby producing an impregnated fiber bundle 504a. This wet winding impregnation process is performed by Figure 5 , and more specifically represented by block 214 .

[0107] The impregnated fiber tow 504a is then fed directly to a winding apparatus 510 that includes one or more winding heads 512. In this embodiment, for simplicity, only one winding head 512 is shown. In other embodiments, there may be multiple winding heads, such as a winding head for each fiber tow. The winding apparatus 510 is configured to wind the impregnated fiber tow 504a onto a pad 514 using one (or more) winding heads 512. Thus, by moving the winding head 512 relative to the pad 514, the winding apparatus 510 forms one or more fiber layers 516 on the pad 514. The winding apparatus can apply the impregnated fiber tow 504a as a spiral winding and / or a cylindrical winding. This operation of winding the fiber onto the pad by the winding apparatus is Figure 5 denoted by block 206. It will be appreciated that, typically in this wet winding process, impregnation of the fibers may be performed just prior to winding the fibers onto the mat, ie, between unwinding the fiber bundle from the bobbin and winding the fibers onto the mat in a continuous process.

[0108] Finally, after winding (or other application of the fibers and matrix to the liner), the liner 514 covered by the fiber layer 516 is cured to harden the fibers and their associated matrix into the shell of the pressure vessel, such as by Figure 5 As represented by block 208 .

[0109] It should be understood that Figure 6 , Figure 7 and Figure 8 The methods and apparatus disclosed in the embodiments of the present invention share some common features, such as providing a matrix (block 202), winding the fibers onto a mat (block 206), and curing (block 208), but the main difference is how the fibers are impregnated with the matrix prior to winding. This is represented by the specific alternatives of blocks 210 / 212 and block 214 within the general impregnation block 204.

[0110] During the curing process represented by block 208 , the matrix may be caused to flow so as to dispose the one or more graphene layers within the housing.

[0111] It will be appreciated that regardless of the method of impregnation of the fiber bundle, during impregnation, most of the resin in the liquid matrix will be "wicked" into the fiber bundle and leave the graphene particles on the surface of the bundle, as shown in FIG. Figure 3 As the graphene particles can be located on all sides of the fiber bundle, a graphene layer can be formed above and below each fiber layer.

[0112] refer to Fig. 9 and Fig.10 , discloses another alternative pressure vessel 600. Fig.11 , another alternative method 700 for manufacturing a pressure vessel is disclosed.

[0113] Fig. 9 Schematically, a cross-sectional view of a pressure vessel 600 for a breathing apparatus (not shown) is shown. In this embodiment, the pressure vessel 600 is a breathing air container. The breathing apparatus may be a self-contained breathing apparatus (SCBA) or a closed circuit breathing apparatus (CCBA).

[0114] The pressure vessel 600 includes a hollow, generally cylindrical body with hemispherical ends. In other embodiments, the pressure vessel 600 may have a different shape, such as a quasi-spherical end.

[0115] The pressure vessel 600 includes a structural shell 602 and a liner 604 that defines an interior volume or chamber V'. In this embodiment, the liner 604 is enclosed by the structural shell 602. The liner 604 is a plastic liner, but may be made of other materials, such as metal, in other embodiments. The liner 604 performs the primary function of providing a barrier to retain the fluid within the pressure vessel 600, and the structural shell 602 encloses the liner 604 so as to protect the liner 604 and increase the strength and structural integrity of the vessel 600. The liner 604 may be substantially impermeable to the fluid it is designed to contain (e.g., breathing air), but may not completely prevent penetration by other substances (e.g., CBRN contaminants).

[0116] The liner 604 has a neck 606 that protrudes from the structural shell 602 at one hemispherical end of the pressure vessel 600. The neck 606 can be connected to a breathing device so that the contents of the pressure vessel can be supplied to the breathing device. The neck 606 can be formed as a separate piece made of a different material than the rest of the liner 604. For example, the neck 606 can be composed of metal, and the rest of the liner 604 can be made of plastic and blow molded around the neck 606 to connect the two parts. In some embodiments, another fitting can be provided at the opposite hemispherical end, for example to allow the liner 604 and the container 600 to be positioned and / or clamped when they are manufactured.

[0117] Now go to Fig.10 , a detailed view of a cross section of the pressure vessel 600 is shown. Fig.10 Shows Figure 1 An exemplary portion of the pressure vessel 600 is indicated at X' in FIG. Fig.10 , the layering and structure of structural shell 602 and liner 604 can be more clearly seen.

[0118] Referring first to the liner 604, it can be seen that the liner 604 is a substantially uniform layer of material, in this case plastic. The liner 604 is arranged to form the innermost surface of the pressure vessel 600 facing the interior volume V'.

[0119] The structural shell 602 covers the liner 604 and, in this embodiment, forms the outermost surface of the pressure vessel 600 that is exposed to the external environment E. In other embodiments, the shell 602 itself will be covered by another one or more layers of material or composite material, such as another protective layer and / or a decorative layer, which will then form the outermost surface of the pressure vessel 600.

[0120] If available Fig.10As will be appreciated in the foregoing, in this embodiment, the structural shell 602 comprises a plurality of components and is therefore a composite shell. In other embodiments, the shell may be non-composite. Generally, the structural shell 602 is formed of a plurality of fibers 608 and a matrix 610. The matrix 610 substantially encapsulates the fibers 608 and itself comprises a resin material.

[0121] During manufacturing, the resin material is initially in liquid form. This liquid form of matrix 610 is coated on the fibers 608, and the fibers 608 are wound in layers on the pad 604. After being wound on the pad 604, the matrix 610 is cured so that the resin material 612 hardens and the graphene particles 614 are arranged into layers. Therefore, during curing, the matrix can flow so as to fix and arrange the graphene particles into one or more graphene layers within the shell.

[0122] In this schematic exemplary illustration of a pressure vessel 600, two fiber layers 616 and 618 are shown. It should be understood that in other embodiments, more fiber layers may be provided.

[0123] As described above, the inner fiber layer 616 is wound as a "hoop" winding layer. The outer fiber layer 618 is also wound as a "helical" winding layer as described above. Alternating annular fiber layers and helical fiber layers can be provided, or multiple adjacent annular layers or helical layers can be provided, or any combination thereof.

[0124] The resin material 612 coats and encapsulates the fibers 608 and the graphene particles 614. The resin material 612 fills the gaps between the fibers 608 and the particles 614.

[0125] If available Fig.10 As best understood in FIG. 6A , the layer 620 of graphene particles 614 is disposed on the outer surface of the liner 604, i.e., between the inner fiber layer 616 and the liner 604. The graphene particles are as described above with respect to Figure 4 A graphene sheet is described.

[0126] The graphene particles 614 reduce the permeability of the structural shell 602 to hazardous substances (e.g., CBRN contaminants) in the same manner as described above for layer 120, and thus inhibit such substances from entering the interior volume V' of the pressure vessel 600. Therefore, a pressure vessel according to the present disclosure can improve the safety of breathing apparatus used in CBRN contaminated environments.

[0127] Thus, pressure vessel 600 includes a permeation barrier layer 620 comprising graphene sheets on an outer surface of a liner. In alternative pressure vessels, or in addition to vessels according to pressure vessel 600, a permeation barrier layer may be formed on an outer surface of a structural shell.

[0128] refer to Fig.11 , discloses a method 700 for making a pressure vessel for a breathing apparatus. In particular, the method 700 is for forming a pressure vessel having a permeation barrier layer on an outer surface of a liner, such as Fig. 9 The pressure vessel is 600.

[0129] Block 702 represents providing a mold for forming a liner for a pressure vessel. The mold includes an interior volume defining a shape for the liner. The interior volume is defined by an interior surface of the mold.

[0130] Next, at block 704, at least a portion of the inner surface of the mold is coated with graphene microparticles or graphene nanoparticles, preferably substantially the entire inner surface of the mold. For example, the graphene particles may be deposited by spraying, brushing, or any other method for depositing particles on the inner surface of the mold. The graphene particles may be as described above with respect to Figure 4 A graphene sheet is described.

[0131] Box 706 represents introducing the gasket material into the mold to form the gasket. In this method, the graphene particles disposed on the mold surface adhere to or bond to the outermost surface of the gasket, so that the manufactured gasket includes graphene particles on its outer surface.

[0132] All of the above-described pressure vessels may be provided as part of a breathing apparatus and the methods may be applied during manufacture of the breathing apparatus.

[0133] It will be understood that the present invention is not limited to the above-described embodiments, and that various modifications and improvements may be made without departing from the concepts described herein. Except for mutually exclusive situations, any feature may be used alone or in combination with any other feature, and the present disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

[0134] For example, within the principles of the present disclosure, it is conceivable to combine Figure 1 The pressure vessel 100 and Fig. 9 The principles of the pressure vessel 600 of the present invention may be applied to pressure vessels having a thermoplastic matrix, thereby eliminating the need for a "curing" step as with a resin-based matrix. In addition, although described with respect to a pressure vessel having a liner, a pressure vessel (e.g., Figure 1 and Figure 2 The pressure vessel 100 may not include the liner 104. The vessel 100 may therefore include a V-tank.

[0135] Furthermore, while one method of forming a pressure vessel including a fiber reinforced polymer composite shell having a graphene sheet has been described above, it is apparent that such a pressure vessel may be formed by other methods. For example, methods that are able to more directly provide graphene sheets between fiber layers may use a graphene sheet ratio outside the 0.1 to 10 wt % range and still be able to form a composite shell having a graphene sheet.

[0136] The inventors have determined that dispersing graphene sheets within a matrix and then impregnating it into a fiber reinforcement may be an advantageous way to increase the impermeability of a pressure vessel. For example, incorporating graphene sheets into a matrix and agitating the matrix may have fewer processing difficulties than other methods that use continuous graphene sheets or foils or indeed provide graphene layers between fiber layers.

[0137] In addition, the inventors have determined that the proportion of graphene sheets as described herein can provide an optimal balance between improved impermeability and matrix viscosity. In addition, incorporating graphene sheets into the matrix at a ratio of 0.1 to 10 wt% can increase the mechanical properties of the shell (e.g., impact resistance).

Claims

1. A breathing apparatus comprising a pressure vessel, the pressure vessel comprising: Fiber reinforced polymer composite shell with graphene sheets.

2. A pressure vessel for a breathing apparatus, the pressure vessel comprising: Fiber reinforced polymer composite shell with graphene sheets.

3. The pressure vessel according to claim 2, wherein: The pressure vessel includes a non-metallic liner, wherein the graphene sheet is disposed between the liner and a fiber reinforcement layer.

4. The pressure vessel according to claim 2 or 3, wherein: The fiber reinforcement includes a first fiber layer and a second fiber layer, the first fiber layer and the second fiber layer being separated by a graphene sheet.

5. The pressure vessel according to claim 4, wherein: The first fiber layer includes fibers wound in a first orientation, and the second fiber layer includes fibers wound in a second orientation different from the first orientation.

6. The pressure vessel according to any one of claims 2 to 5, wherein: The graphene sheets are oriented such that the chemical, biological, radiation and / or nuclear permeability of the composite shell is reduced.

7. The pressure vessel according to any one of claims 2 to 6, wherein: The graphene sheets are typically at a low angle relative to each other, optionally typically at an angle of no more than 15 degrees.

8. The pressure vessel according to any one of claims 2 to 7, wherein: The graphene sheets are oriented substantially parallel to a local surface of the can.

9. The pressure vessel according to any one of claims 2 to 8, wherein: The major axis size within the graphene sheet plane is greater than the fiber diameter of the fiber reinforcement.

10. The pressure vessel according to claim 9, wherein: The in-plane minor axis dimension of the graphene sheet is at least twice the diameter of the fiber.

11. The pressure vessel according to any one of claims 2 to 10, wherein: The in-plane major axis dimension of the graphene sheet is about 8-50 microns, preferably about 20 microns.

12. The pressure vessel according to any one of claims 2 to 11, wherein: The fiber reinforced polymer composite housing includes a matrix having 0.1 to 10 wt % graphene sheets.

13. A method of manufacturing a pressure vessel for a breathing apparatus, the method comprising: providing a polymer matrix having at least 0.1 wt % graphene sheets; The fiber reinforcement is impregnated with the matrix.

14. The method according to claim 13, further comprising: The fiber reinforcement is wrapped around a mat or mandrel in a first orientation to form a first layer of fiber reinforcement.

15. The method according to claim 14, further comprising: The fiber reinforcement is wrapped around the mat or the mandrel in a second orientation different from the first orientation to form a second layer of fiber reinforcement.

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