WO2018069662A1

WO2018069662A1 - Calibration fluid and/or sample container

Info

Publication number: WO2018069662A1
Application number: PCT/GB2016/053167
Authority: WO
Inventors: Tom Knight; Jeremy Knight
Original assignee: JDSE Ltd
Current assignee: JDSE Ltd
Priority date: 2016-10-12
Filing date: 2016-10-12
Publication date: 2018-04-19
Anticipated expiration: 2019-04-12

Abstract

A calibration fluid container and/or sample fluid container10for fluid containment and which comprises a container body (12) formed from at least first and second mutually engagable container body portions (14). Each container body portion (14) has an internal surface (8) which defines an inner volume. A fluid chamber (38) being devoid of threads and having a smoothed and passivated contiguous chamber surface when in an engaged condition is defined. The container (10) further comprises a fluid port (32) in fluid communication with the fluid chamber (38), the or each said fluid port (32) having a fluid-flow opening on the internal surface of the respective container body portion (14). A method of manufacturing and/or method of reducing dead-space/flow disturbance in such a container is also provided.

Description

Calibration Fluid And/Or Sample Fluid Container

The present invention relates to a calibration fluid container and/or sample-fluid container, in particular but not necessarily exclusively to a sample cylinder for containing calibration gas mixtures for ultra-high-purity or trace element fluids and samples. The invention further relates to a method of manufacturing such a calibration fluid container and/or sample fluid container and to a method of reducing flow disturbance and/or dead spaces in a calibration fluid container and/or sample fluid container.

Calibration fluid containers are used to contain fluid samples and/or calibrating fluid which can be utilised, for example, in metrology of trace elements, ultra-pure fluids, or fluids placed under extreme temperatures or pressures. The fluid is retained inside the calibration fluid container, acting either as a reservoir prior to passing to a sensing instrument, such as a chromatograph, or may be used to calibrate such a sensing instrument.

There are a few challenges to be overcome with respect to adequate containment of ultra-high-purity or trace element gas samples. In the case of active fluids, such as fluids which are corrosive, unstable, and/or reactive, there can be an issue of contamination of the contained fluid causing degradation of the contained fluid, particularly but not necessarily exclusively at or adjacent to valves controlling the flow of fluid to the calibration fluid container. This is a particular problem for screw-threaded joints, which typically use sealing compounds or tapes to stop leakage along the screw-thread pathway to make it fluid-tight. Another concern relating to calibration fluid containers is the problem of sorption effects, including both adsorption and desorption effects, on the internal surfaces of the calibration fluid container. In particular, adsorption onto the inner surfaces of containers which are reactive with the fluid to be contained is a serious problem. This is highly significant if the calibration fluid container is to be used in connection with a trace or plurality of mutually reactive substances.

Sorption effects can be minimised by treating the inner surfaces of the calibration fluid container, for example, by passivation of the surface, for example, by electropolishing. This smooths the metallic surface at the micro- and nanoscopic scale, limiting the ability of fluid molecules to adsorb onto the internal surface which could otherwise increase or decrease the free concentration of such molecules or contaminate ultra-pure gas mixtures.

Sorption effects are also minimised by providing internal surfaces which are as smooth as possible, and smooth internal surfaces also minimise flow disturbance inside the calibration fluid container, leading to a smooth fluid flow through the system. However, in order to minimise the number of joints required to form a calibration fluid container, the container is typically formed as a cylinder, which is either extruded or spun as a unitary piece of metal, inclusive of the fluid inlet and outlets into which valves are typically screwed. This results in an internal surface which has restricted access from the outside of the cylinder, making techniques such as mechanical smoothing or electropolishing very challenging to perform to an adequate and verifiable standard.

A fluid sample container is herein and throughout defined as or is intended to mean a container suitable for receiving an extracted representative fluid sample of a fluid for compositional analysis and, in particular, analysis of trace compounds. Such a container has the same or similar issues or requirements as those described above with reference to the calibration fluid container.

It is an object of the present invention to provide a calibration fluid and/or fluid sample container which allows for the internal surface of the container to be smoothed and passivated easily, whilst eliminating the problems associated with having screw-threaded joints.

According to a first aspect of the invention there is provided a calibration fluid and/or fluid sample container for fluid containment, the calibration fluid container and/or sample fluid container comprising: a container body formed from at least first and second mutually engagable container body portions, each container body portion having an internal surface which defines an inner volume, the inner surfaces of the container body portions defining a fluid chamber being devoid of threads and having a smoothed and passivated contiguous chamber surface when in an engaged condition; and one or more fluid ports in fluid communication with the fluid chamber, the or each said fluid port having a fluid-flow opening on the internal surface of the respective container body portion.

By providing a calibration fluid container and/or sample fluid container which is comprised of a plurality of container body portions so as to permit access to the internal surfaces of the calibration fluid container and/or sample fluid container prior to assembly, it is possible to improve the smoothing and treating of the inner surfaces, for example, using electropolishing and/or applying a passive coating. Whilst doing so, it is still possible to maintain a threadless, smooth, contiguous surface at or adjacent to the joints, thereby limiting the likely sorption effects that would otherwise result. The terms or phrases 'threadless' or 'devoid of threads', used herein and throughout, are intended to mean that the portion of the fluid chamber in contact with a gas or liquid held therein is without a thread, typically but not necessarily exclusively being a screw-thread. This beneficially allows the manufacture of a calibration fluid container and/or sample fluid container which is less likely to become contaminated due to said sorption effects, which might otherwise affect the accuracy of measurements taken downstream of the calibration fluid container and/or sample fluid container, for example. This allows the calibration fluid container and/or sample fluid container to be used for ultra-high-purity or trace element fluid sampling.

Ideally, the threadless, smoothed and passivated chamber surface may have a roughness of less than or equal to 0.40 microns RA, and more preferably has a roughness of less than or equal to 0.25 microns RA.

The smoothness of the chamber surface is critical in minimising flow disturbance and sorption effects, and the lower the surface roughness or the smoother, the better. This may also be known in the technical field as an 'RA' value, and for example the preferred or required smoothness or 'RA value' may be less than or equal to 0.4 microns, and more preferably at, approximately or lower than 0.25 microns.

The first and second container body portions may be provided as end cap container body portions, inlet/outlet said fluid port or ports being provided in each of the end cap container body portions. Preferably, the or each said fluid port may be integrally formed as one-piece with the respective container body portion. Furthermore, one, two or more fluid ports may be provided at only one or both of the first and second mutually engagable container body portions.

By providing two distinct end caps, each having a fluid port, there is a definite fluid pathway defined through the volume of the calibration fluid container and/or sample fluid container, allowing the calibration fluid container and/or sample fluid container to be positioned in-line with and/or to allow flow through an existing pipe manifold, for instance, whilst minimising the overall disturbance to the fluid flow therein. The two end caps could be directly engaged to create a fluid chamber having a relatively small volume.

In a preferred embodiment, there may comprise at least a further container body portion interposed between the first and second container body portions, said further container body portion having a further internal surface which is smoothed and passivated to define in part said fluid chamber.

A central container body portion or portions intermediate to the end caps may be used to provide the majority of the internal volume of the calibration fluid container and/or sample fluid container. It will be apparent that identical end caps could be used for a plurality of different sample cylinders, with different central container body portions being utilised in order to alter the dimensions of the calibration fluid container and/or sample fluid container as a whole. This modularity advantageously reduces the overall cost to manufacture a plurality of containers of different internal volumes. The internal surfaces of the container body portions may be mechanically smoothed prior to passivation, may be electropolished, and/or may be covered with a passive coating, such as a silicone-based coating.

Because the container body portions are separable, allowing access to the internal surfaces, machine tools can access the internal surfaces so as to be mechanically smoothed. The exposure of the internal surfaces of the container body portions prior to assembly of the final calibration fluid container and/or sample fluid container allows for better or improved treatment of the internal surfaces. An expected use would be to passivate the internal surfaces in a better or improved manner which would not otherwise be possible for a calibration fluid container and/or sample fluid container having a unitary container body, for instance, by the use of electropolishing or application of a passive coating.

An engagement interface of each container body portion may be formed as a flat perimeter surface, mutually co-operable with a corresponding engagement interface on another container body portion, the engagement interfaces being suitable for welding, preferably electron beam, laser, fusion or orbital welding. Similarly, an exterior end of the or each fluid port distal to the fluid chamber may be formed as a flat perimeter surface being suitable for welding, preferably, electron beam, laser, fusion or orbital welding, with which may be associated a fluid-control valve or other suitable flow control device. In a preferred embodiment, the container body portions may be devoid of screw-threaded engagement portions, and/or the inner surface of the fluid chamber may be devoid of a screw-thread.

By providing clean, flat surfaces on the container body portions which are mutually compatible, it is possible to ensure that the components can be cleanly welded to one another, ensuring that the joints between component parts are robustly held together without leaks, whilst also maintaining a contiguous overlap between the inner surfaces of the container body portions which might otherwise increase sorption of undesirable molecules. Providing a calibration fluid container and/or sample fluid container which is completely welded together, the potential for fluid escape pathways through screw-threads is advantageously eliminated.

Optionally, there may further comprise a welding and/or bonding alignment element associated with at least one of the container body portions, which may have a circular or non-circular, such as polygonal, for example square or rectangular, profile.

By providing welding and/or bonding alignment elements which allow the various container body portions to be clamped or otherwise gripped during the welding process, a calibration fluid container and/or sample fluid container can be very accurately joined, for example, by electron beam, laser, fusion or orbital welding, whilst still readily maintaining a smooth, preferably cylindrical, inner surface, which limits the sorption effects on the internal surface of the calibration fluid container and/or sample fluid container.

The or each container body portion may beneficially include a body of a fluid-control device, such as a valve, integrally formed therewith as one-piece. This is advantageous in preventing or limiting unintentional damage to the valve body, particularly at the interface with the fluid port. In this case, an interior of the container body portion may be contiguous with an inlet of the fluid-control device. In other words, the fluid-control device is preferably at least in part integrally formed within the container body portion.

The calibration fluid container and/or sample fluid container may be provided in the form of a kit of parts, or may be provided as a fully-assembled unit. According to a second aspect of the invention, there is provided a method of manufacturing a calibration fluid container and/or sample fluid container with an inner surface of a fluid chamber being devoid of a screw-thread, the method comprising the steps of: a] providing a calibration fluid container and/or sample fluid container, preferably in accordance with the first aspect of the invention; b] smoothing the internal surfaces of the container body portions; c] bringing the container body portions into contact at engagement interfaces thereof; and d] welding and/or boding the engaged container body portions to one another to form a calibration fluid container and/or sample fluid container, wherein, subsequent to step b], the internal surface of the container body portions are also passivated. By welding adjacent container body portions together to form a calibration fluid container and/or sample fluid container, it is possible to eliminate many of the undesirable qualities associated with screw-threaded engagement, such as through incorrectly or incompletely engaged components. This is a particular issue with co-operating screw-threaded components which can lead to fluid escape pathways from inside the calibration fluid container and/or sample fluid container. This potential leak path issue can be exacerbated if the screw-threaded components are over-tightened.

The passivation may be achieved by using electropolishing, and/or by forming a passive coating on the internal surfaces, such as a silicone coating which is applied to the internal surfaces. Optionally, there may further comprise a step subsequent to step d] of X-ray testing and/or leak-testing the welding and/or bonding.

Since the internal surfaces of the container body portions are exposed prior to assembly of the calibration fluid container and/or sample fluid container, it is possible to better or improve a smoothness and treatment of the internal surfaces, in particular to achieve passivation of the internal surfaces. This advantageously limits the degree to which sorption of undesirable molecules on the internal surfaces can contaminate or distort the fluid sample, which could feasibly result in undesirable reactions or inaccuracies creeping into measurements, for example in a fluid pipe manifold which contains the calibration fluid container and/or sample fluid container. Furthermore, by improving the passivation of the internal surfaces, adsorption of molecules from a fluid sample is prevented or limited, thereby preventing or reducing an alteration of the sample. During step d], the welding may be performed via one of electron beam, laser, fusion or orbital welding. Additionally or alternatively, there may be a further step e] of providing at least one fluid-control valve engagable with the or each fluid port; and step fj of welding the engaged fluid-control valve to the or each fluid port. During step fj, the welding may be performed via orbital welding. The method may also further comprise a step g] subsequent to step f] of providing a cap element engagable with the or each fluid-control valve to protect the valve during transit.

Orbital, electron beam, laser or fusion welding of the joints between the container body parts ensures an even weld, resulting in minimal interference with the internal surfaces of the calibration fluid container and/or sample fluid container during the assembly process. By also welding the fluid-control valves to the calibration fluid container and/or sample fluid container, it is possible to further mitigate the deleterious effects associated with having screw-threaded engagement, whilst also providing a means of isolating the fluid chamber within the calibration fluid container and/or sample fluid container; this feasibly allows each container to be transported having a fluid, which may be inert or reactive, contained within the fluid chamber, reducing the likelihood of contaminative interaction with, for example, atmospheric gases. A cap element serves to further protect the valves in transit.

According to a third aspect of the invention there is provided a method of reducing dead-space and/or flow disturbance in a calibration fluid container and/or sample fluid container, preferably in accordance with the first aspect of the invention, the method comprising the steps of providing a multi-part container having inner surfaces which are smoothed and passivated to define a contiguous or substantially contiguous threadless fluid chamber, at least one of the container parts having one or more fluid ports in fluid communication with the fluid chamber, the or each said fluid port having a fluid-flow opening on the internal surface of the respective container body portion.

By integrating the fluid ports of the calibration fluid container and/or sample fluid container, rather than providing inwardly projecting fluid flow tubes, it is possible to minimise the disruption to effective fluid flow within the container, whilst also simultaneously minimising the sorption effects at the fluid port entrance to the fluid chamber. The phrase 'dead-space' is well known and understood in this technical field, and the presence of dead-space can lead to undesirable retention of molecules or particulates causing contamination, both by addition or subtraction, of gas or liquid held in the container.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a plan view of a first embodiment of a calibration fluid container and/or sample fluid container, in accordance with the first aspect of the invention;

Figure 2 shows a cross-sectional view through a central longitudinal plane of the calibration fluid container and/or sample fluid container of Figure 1;

Figure 3 shows a plan view of the calibration fluid container and/or sample fluid container of Figure 1 in an assembled condition;

Figure 4 shows a diagrammatic representation of a method of manufacturing the first embodiment of the calibration fluid container and/or sample fluid container, shown in Figures 1 to 3 and in accordance with the second aspect of the invention;

Figure 5 shows a second embodiment of a calibration fluid container and/or sample fluid container, in accordance with the first aspect of the invention and incorporating integral valves; and

Figure 6 is a generalised flow chart of a method of manufacturing the second embodiment of the calibration fluid container and/or sample fluid container, in accordance with the invention. Referring firstly to Figures 1 and 2, there is shown a first embodiment of a calibration fluid container and/or sample fluid container, indicated globally at 10, for the containment of fluid samples, in particular ultra-high-purity fluid or trace element samples. Examples of such fluid samples might extend to high temperature or pressure acids or alkalis, explosive gases such as hydrogen or methane, or highly toxic and corrosive gases such as chlorine or hydrogen sulphide. Calibration fluid containers and/or sample fluid containers therefore need to be able to withstand the rigours of transporting a wide- variety of such fluids.

The calibration fluid container and/or sample fluid container 10 has a container body 12 which comprises a plurality of container body portions 14 interengaged to form the assembled container body 12. In the depicted embodiment, there are three container body portions 14: a central container body portion 14a and first and second end cap container body portions 14b. It will be appreciated that the provision of three container body portions 14 is sufficient to create an elongate calibration fluid container and/or sample fluid container 10 as depicted; however, any number or shape of mutually interengagable container body portions 14 could be provided. For example, only the first and second end cap container body portions 14b could be provided so as to create a far shorter calibration fluid container and/or sample fluid container, or multiple central container body portions 14a could be provided so as to lengthen the calibration fluid container and/or sample fluid container. The embodiment of the calibration fluid container and/or sample fluid container 10 as depicted is therefore for illustrative purposes only.

The central container body portion 14a is formed as an elongate cylindrical tube 16 formed from a suitably unreactive metal, such as stainless steel, glass, or possibly some unreactive plastics and has a, preferably cylindrical, inner surface 18a of uniform diameter along its longitudinal extent. The inner surface 18a of the central container body portion 14a thereby defines a cylindrical volume 20a therein.

On the external surface 22a of the central container body portion 14a is provided a welding and/or bonding alignment element 24a, which is here integrally formed with the external surface 22a of the central container body portion 14a, but could be releasably engagable therewith. The welding and/or bonding alignment element 24a is formed having a circular or non-circular, preferably polygonal, in this case square or rectilinear profile for simple retention within a clamping device to enable steady welding, and a plurality of screw-threaded apertures 26 are also provided to both facilitate clamping and permit attachment of the assembled calibration fluid container and/or sample fluid container 10 to other objects.

Each of the end cap container body portions 14b is formed as a, preferably cylindrical, block 28 which is capped at one end by an outer wall portion 30, through which extends a fluid port 32, which can act as either a fluid inlet or fluid outlet, and is open at its other end. Similarly to the central container body portion 14a, the end cap container body portions 14b are preferably formed from a suitably unreactive metal, such as stainless steel, glass, or possibly some unreactive plastics.

At the open end, the perimeter 34 of the cylindrical block 28 is flat and smooth, and is complementarily shaped to the perimeter 36 of the cylindrical tube 16 of the central container body portion 14a. The two perimeters 34, 36 thereby form an engagement interface with one another. Whilst a fluid port 32 is illustrated at either end of the calibration fluid container and/or sample fluid container 10, it will be appreciated that any appropriate fluid port to the inside of the calibration fluid container and/or sample fluid container 10 could be provided. A single tube, acting as both fluid inlet and outlet could be provided, or a plurality of fluid inlets and/or outlets could also be provided.

The inner surface 18b of each end cap container body portion 14b at the open end is formed so as to flushly match the shape of the inner surface 18a of the central container body portion 14a, the walls of the inner surface 18b of the end cap container body portion 14b converging to form an internal dome adjacent to the outer wall portion 28, from which the fluid port 32 extends. The inner surface 18b thereby defines a capped cylindrical volume 20b.

As with the central container body portion 14a, there is a welding and/or bonding alignment element 24b affixed to the external surface 22b of each end cap container body portion 14b, within which may again be provided a plurality of screw-threaded apertures 26. The threads can be seen in the cross-section of Figure 2. The welding and/or bonding alignment element 24b similarly may have a matching or substantially matching profile, in this case preferably being a square or rectilinear profile.

The complete modular calibration fluid container and/or sample fluid container 10 is assembled as shown in Figure 3; one end cap container body portion 14b is engaged at either end of the central container body portion 14a. The combined inner surfaces 18a, 18b of the central container body portion 14a and end cap container body portions 14b are complementarily shaped so as to form a smooth, contiguous inner surface 18 for the calibration fluid container and/or sample fluid container 10 as a whole, indicated by the dashed lines in Figure 3. The inner surface 18 defines a fluid chamber 38 of the calibration fluid container and/or sample fluid container 10, the volume of which is defined by the sum of the volumes 20a, 20b of the container body portions 14. This volume is preferably devoid of screw-threads, and is both smooth and passivated; this limits sorption onto the surface, whilst also reducing surface roughness which might disturb or interfere with fluid flow within the fluid chamber 38.

To secure the container body portions 14 so as to form the calibration fluid container and/or sample fluid container 10 in its assembled state, the container body portions 14 are welded together along the respective perimeters 34, 36 of the individual central or end cap container body portions 14a, 14b. As the illustrated calibration fluid container and/or sample fluid container 10 is largely cylindrical, the central or end cap container body portions 14a, 14b can be held in place using the welding and/or bonding alignment elements 24a, 24b and then orbital welded about the perimeters 34, 36. The container body portions 14a, 14b could feasibly be initially held in place using screw-threaded engagement prior to welding, but it is preferred that the container body portions 14 include no screw-threaded portions, with the exception of the screw-threaded apertures 26. Alternatively shaped calibration fluid container and/or sample fluid containers 10 may need to be welded using different welding techniques, however.

The assembled modular calibration fluid container and/or sample fluid container 10 therefore defines a complete fluid chamber 38 which has only two welded joints 40, and two fluid ports 32 leading therein, acting as fluid-flow openings into the fluid chamber, in this case, a fluid inlet and a fluid outlet. In this instance, the fluid chamber 38 is substantially prolate.

The advantage of the calibration fluid container and/or sample fluid container 10 as described over unitarily-formed sample cylinders is that, prior to assembly, the internal surfaces 18a, 18b of the central and end cap container body portions 14a, 14b can be better mechanically smoothed, using physical machining tools, and subsequently passivated to limit the effects of sorption. This passivation would primarily be achieved using electropolishing, which involves the insertion of the container body portions 14 into an electrolyte to electrochemically smooth the internal surfaces 18a, 18b, the container body portion 14 acting as an anode in the electrochemical cell. Ideally, the internal surfaces 18a, 18b are smoothed so as to have a surface roughness of less than 0.40 microns, and preferably less than 0.25 microns, in order to minimise sorption effects.

Additionally or alternatively, the passivation could be achieved by the application of a physically and/or chemically inert passive coating to the internal surfaces 18a, 18b, such as a silicone-based coating. One example of such a coating might be a silicone-based coating such as SilcoNert 2000 RTM available from SilcoTek, 225 PennTech Drive, Bellefonte, PA 16823, USA; other similarly inert coatings are available. Other means of passivation of a metal surface will be apparent to the skilled reader, and the above-mentioned techniques do not represent an exhaustive list.

It is possible and may be advantageous to apply an inert coating, such as the aforementioned SilcoNert 2000 RTM, after the welding and/or bonding. This would not only cover the internal weld area, but will also reduce possible degradation of the coating in the heat affected zone.

The calibration fluid container and/or sample fluid container 10 may be supplied in its complete form, or as a kit of parts to be welded together. However, it may also be provided inclusive of one or more fluid control valves, such as the ball taps 42 illustrated in Figure 3. These taps 42 would typically have a passivated inner surface for use with aggressive fluids which might otherwise distort the contained fluid similar to the internal surface of the container, and are capable of either activating or deactivating flow control to the calibration fluid container and/or sample fluid container 10. More complicated valves, which provide a degree of flow modulation, could also be considered, and many types and form of valve are known in the art.

In this instance, the taps 42 have a flat perimeter inlet 44 which is mutually compatible with an outer perimeter 46 of the fluid ports 32. This allows the taps 42 to be welded to the fluid inlet or outlet of the calibration fluid container and/or sample fluid container 10, preferably using orbital welding, which removes the need for screw-threaded connectors, which may otherwise result in leakage or contamination from the joints.

In a preferred method of forming the assembled modular calibration fluid container and/or sample fluid container 10, indicated globally as S100 in Figure 4, the container body parts 14 are provided at step SI 10. The internal surfaces 18 of each container body part 14 are then physically smoothed at step S120. Each container body portion 14 may then have its internal surface 18 passivated at step S130, preferably by a combination of electropolishing and/or coating with a silicone covering, such as SilcoNert 2000 RTM. This renders the internal surface 18 highly resistant to sorption effects. Alternatively, the coating may be applied after assembly, welding and/or bonding.

Once the internal surfaces 18 have been passivated and are ready to be connected, the respective container body portions 14 are brought into engagement at step SI 40 at their perimeters 34, 36. At this point, the container body portions 14 can be held in place via the welding and/or bonding alignment elements 24a, 24b, and the container body portions 14 can be welded at step S150 at the perimeters 34, 36, preferably via a permanent fastening means, such as welding, for example, electron beam, laser, fusion or orbital welding to create a secure and uniform weld. It may also be feasible to utilise bonding as the permanent fastening means, such as molecular bonding, providing the interior smoothness of the fluid contact surface is maintained or improved. Depending how the modular calibration fluid container and/or sample fluid container 10 is to be provided, fluid-control valves 42 may be provided, which can also be welded in place at step SI 60 so as to be in engagement with the fluid ports 32 forming the fluid inlet and outlet. Passivation, as discussed above, may take place if not already undertaken either after attachment of the valves at SI 60, see step SI 62, or prior to attachment of the valves or other flow control means at step SI 66. As necessity dictates, valve parts may be added to the attached valve body at SI 64.

Once the calibration fluid container and/or sample fluid container 10 is fully assembled, the quality of the welding can be tested at step SI 70, with the joints 40 being X rayed and/or leak-tested. This may be repeated, and may take place prior or subsequent to passivation and/or smoothing, and/or prior or subsequent to mounting of the fluid-flow control devices, in this case being preferably valves, and/or prior or subsequent to application of parts of the fluid-flow control device or devices, such as the valve parts.

If fluid-control valves 42 have been provided, then, prior to transit, it may be preferable to attach protective cap elements at step SI 80 to the outwardly-facing ends of the fluid-control valves 42. The cap elements can be attached, releasably or otherwise, to the container body 12 in order to prevent accidental dislocation of the cap elements.

As previously discussed, there is no specific requirement for a calibration fluid container and/or sample fluid container to be formed as a cylinder, although a cylindrical or prolate inner surface which is smoothly curved will limit the potential for sorption to occur, whilst minimising fluid-flow disturbance inside the fluid chamber. Consequently, it is generally accepted that from the perspective of manufacturing efficiency, the calibration fluid container and/or sample fluid container should be externally cylindrical, thereby utilising the minimum amount of material to form the container. It will be apparent that any shape or arrangement of container body portions could be utilised in order to create the assembled calibration fluid container and/or sample fluid container.

Referring now to Figures 5 and 6 of the drawings, there is shown a second embodiment of a calibration fluid container and/or sample fluid container. Parts which are similar to those of the first embodiment utilise the same reference with 100 added, and further detailed description is omitted for brevity. As above, calibration fluid container and/or sample fluid container 110 is specifically for the containment of fluid samples, and more particularly but not necessarily exclusively ultra-high-purity or trace element fluid samples. The calibration fluid container and/or sample fluid container 110 has a container body 112 which comprises a plurality of container body portions 114 interengaged to form the assembled container body 112. Although three container body portions 114 are provided, being a central container body portion 114a and first and second end cap container body portions 114b, two container body portions or more than three container body portions may be utilised to provide a modular device.

Each end cap container body portion 114b may include the fluid control devices 142 integrally formed therewith as one-piece. By dispensing with the elongate fluid port 32 (see Figure 3) at each end and having a direct or substantially direct interface port 145 between the body of the valve or tap 142 at each end of the fluid chamber 138, the required volume of the fluid chamber 138 can be optimised relative to the length of the fluid container 110. In other words, an end-to-end length of the fluid container 110 including the fluid control devices 142 can be shortened whilst maintaining the same interior fluid chamber length. The above-described embodiment is also advantageously more robust, due to the or each flow control device body 142a being integrally formed as one-piece with the respective end cap container body portion 114b. Without the device body projecting from the end cap container body portion 114b in a cantilevered manner via the elongate fluid port 32, there is less likelihood of damage or breakage during storage, transit or use.

Furthermore, by integrally forming the fluid control body 142a with the end cap container body portion 114b, and therefore all as a one-piece block of material couplable with each end or the central container body portion 114a, a connection, typically being a welded joint, is avoided at the elongate fluid port interconnecting the fluid control device body 142a and the end cap container body portion 114b. Consequently, this results in a more robust arrangement allowing the option for significantly higher fluid pressures to be accommodated within the interior volume without or with less risk of fracture or leakage. Being able to accommodate pressures from 0 bar or 0 kPA to 1000 bar or 100 MPa and higher may be of particular use in the emerging technical field of hydrogen storage and use. As above, although the fluid control device bodies 142a, in this case being valve bodies, are integrally incorporated at both ends of the fluid container 10, a single, double or more valve body allowing inlet and outlet control of liquid or gas could be provided at one end only. In this case, the or each valve body, preferably with two valves associated therewith, may again be formed as one-piece with the container body portion 114a, 114b. As such, only a single end cap container body portion 114b may be required, with the central body portion 114a being bottomed and therefore closed at one end or vice versa.

In a preferred method of forming the assembled modular calibration fluid container and/or sample fluid container 10, indicated globally as SI 00 in Figure 4

Similarly to the production steps discussed with reference to Figure 4 above, to assemble the modular calibration fluid container and/or sample fluid container 110, indicated globally as S200 in Figure 6, the container body parts 114 are provided at step S210, and physically treated as required at S220. Passivation to render the internal surface 118 highly resistant to sorption effects may take place at step S230, and this may include passivation of the valve bodies of the integrated valves 142. Alternatively, the coating may be applied after assembly, welding and/or bonding, see below. Once the internal surfaces 118 have been passivated, if required at step S230, and are ready to be connected, the respective container body portions 114 are brought into engagement at step S240. The container body portions 114 can be welded and/or bonded at step S250.

If not already undertaken, the internal surfaces of the valves or other flow control device 142 along with the other internal surfaces of the container are passivated at step S262, and valve parts which are typically supplied already smoothed and/or passivated are assembled at step S264.

Once the calibration fluid container and/or sample fluid container 110 is fully assembled, the quality of the welding and/or bonding can be tested at step S270, with the joints being X rayed and/or leak-tested. Optionally, X-ray and/or leak testing may take place before the valve parts or other flow control components are incorporated. This testing may be repeated, and may take place prior or subsequent to passivation and/or smoothing, and/or prior or subsequent to application of parts of the fluid-flow control device or devices, such as the valve parts. Protective cap elements are preferably mounted at step S280 to the outwardly-facing ends of the fluid-control valves 142 for protection.

The present method of manufacturing a calibration fluid container and/or sample fluid container also does not necessarily have to be used to passivate the internal surfaces of the container body portions. Any action which might need to be performed to the internal surface of the container prior to assembly would feasibly benefit from such a method of construction. For example, it may be desirable to etch the internal surface, or chemically activate or deactivate the surface for catalytic uses.

It is therefore possible to provide a modular calibration fluid container and/or sample fluid container for a fluid, in particular an ultra-high-purity or trace element fluid, a container body of which is formed from a plurality of discrete container body portions which are mutually engagable. This beneficially allows the user to treat the internal surfaces of the calibration fluid container and/or sample fluid container prior to assembly, for example, allowing for the internal surfaces to be passivated with respect to sorption effects.

Furthermore, the container body parts may be welded together in such a manner so as to remove the need for screw-threaded joints, which can lead to routes for fluid egress, weakening the joints of the calibration fluid container and/or sample fluid container and increasing the risk of sample contamination. Although orbital welding may be utilised, any other suitable permanent engagement means may be considered, such as electron beam welding, fusion welding and/or laser beam welding, and/or bonding as described above.

The words 'comprises/comprising' and the words 'having/including' when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. The embodiments described above are provided by way of examples only, and various other modifications will be apparent to persons skilled in the field without departing from the scope of the invention herein described and defined.

Claims

1. A calibration fluid and/or fluid sample container for fluid containment, the calibration fluid container and/or sample fluid container comprising: a container body formed from at least first and second mutually engagable container body portions, each container body portion having an internal surface which defines an inner volume, the inner surfaces of the container body portions defining a fluid chamber being devoid of threads and having a smoothed and passivated contiguous chamber surface when in an engaged condition; and one or more fluid ports in fluid communication with the fluid chamber, the or each said fluid port having a fluid-flow opening on the internal surface of the respective container body portion.

2. A calibration fluid container and/or sample fluid container as claimed in claim 1, wherein the smoothed and passivated chamber surface has a roughness of less than or equal to 0.40 microns RA.

3. A calibration fluid container and/or sample fluid container as claimed in claim 2, wherein the smoothed and passivated chamber surface has a roughness of less than or equal to 0.25 microns RA.

4. A calibration fluid container and/or sample fluid container as claimed in any one of claims 1 to 3, wherein the first and second container body portions are provided as end cap container portions, a said fluid port being provided in at least one of the end cap container body portions.

5. A calibration fluid container and/or sample fluid container as claimed in any one of claims 1 to 4, wherein two or more fluid ports are provided at one or both of the first and second mutually engagable container body portions.

6. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, wherein the or each said fluid port is integrally formed as one-piece with the respective container body portion.

7. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, further comprising at least a further container body portion interposed between the first and second container body portions, said further container body portion having a further internal surface which is smoothed and passivated to define in part said fluid chamber.

8. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, wherein the internal surfaces of the container body portions are mechanically smoothed prior to passivation.

9. A calibration fluid container and/or sample fluid container as claimed in any one of claims 1 to 8, wherein the internal surfaces of the container body portions are passivated by electropolishing.

10. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, wherein the surfaces of the fluid chamber are covered with a passive coating.

11. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, further comprising a fluid-control device associated with the fluid port.

12. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, wherein the container body portions are devoid of screw-threaded engagement portions.

13. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, wherein the inner surface of the fluid chamber is devoid of a screw-thread.

14. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, further comprising a welding and/or bonding alignment element associated with at least one of the container body portions.

15. A calibration fluid container and/or sample fluid container as claimed in any one of claims 1 to 4, wherein the or each container body portion includes a body of a fluid-control device integrally formed therewith as one-piece.

16. A calibration fluid container and/or sample fluid container as claimed in claim 15, wherein an interior of the container body portion is contiguous with an inlet of the fluid-control device.

17. A calibration fluid container and/or sample fluid container as claimed in claim 15 or claim 16, wherein the fluid-control device is at least in part integrally formed within the container body portion.

18. A calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims, provided in the form of a kit of parts.

19. A method of manufacturing a calibration fluid container and/or sample fluid container with an inner surface of a fluid chamber being devoid of a screw-thread, the method comprising the steps of: a] providing a calibration fluid container and/or sample fluid container as claimed in any one of the preceding claims; b] smoothing the internal surfaces of the container body portions; c] bringing the container body portions into contact at engagement interfaces thereof; and d] welding and/or boding the engaged container body portions to one another to form a calibration fluid container and/or sample fluid container, wherein, subsequent to step b], the internal surface of the container body portions are also passivated.

20. A method as claimed in claim 19, further comprising a step subsequent to step d] of X-raying and/or leak-testing the welding and/or bonding.

21. A method as claimed in claim 19 or claim 20, wherein during step d], said welding is performed via one of electron beam, laser, fusion or orbital welding.

22. A method of reducing dead-space and/or flow disturbance in a calibration fluid container and/or sample fluid container as claimed in any one of claims 1 to 21, the method comprising the steps of providing a multi-part container having inner surfaces which are smoothed and passivated to define a contiguous or substantially contiguous threadless fluid chamber, at least one of the container parts having one or more fluid ports in fluid communication with the fluid chamber, the or each said fluid port having a fluid-flow opening on the internal surface of the respective container body portion.