WO2016180989A1

WO2016180989A1 - Pressure vessel

Info

Publication number: WO2016180989A1
Application number: PCT/EP2016/060946
Authority: WO
Inventors: Phillip Wallis
Original assignee: EMMERALD POLYMERS Ltd
Current assignee: EMMERALD POLYMERS Ltd
Priority date: 2015-05-14
Filing date: 2016-05-16
Publication date: 2016-11-17
Anticipated expiration: 2017-11-14
Also published as: GB201508263D0

Abstract

A pressure vessel comprising a container to hold contents under pressure. The container has an opening for filling or emptying the container on one end, the opening surrounded by a threaded neck formed with a buttress thread to receive a valve assembly and a sealing gasket on the side of the thread remote from the end of the container. A head locates on the one end of the container and has a plurality of downwardly projecting circumferentially spaced fingers; and a base locates on the opposed other end and has a plurality of upwardly projecting circumferentially spaced fingers, that inter-fit in a non-overlapping manner with those of the head. A sump is formed in the other end of the container and a part of valve assembly extends into that when fitted to the neck. A retaining ring locates around the fingers and holds them against the container to hold the head, base and ring together and resist expansion of the container; and at least two rolling rings separate from the retaining ring that locate around the base and/or head. The parts are made from plastics material, and the head and base are provided with a handling ring in which one or more hand-hold is integrally formed.

Description

Pressure Vessel

The present invention relates to a pressure vessel and in particular a pressure vessel for the storage and/or transport of pressurised contents.

Certain products are stored and transported in, or dispensed from containers such as barrels and kegs, under raised pressure. This is done for a variety of reasons, including maintaining the characteristics of the product, increasing the quantity of product that fits in a certain volume and aiding in the delivery of the product from that storage vessel. One particular instance of particular interest to the present invention relates to drinks such as beers which are stored and transported to their point of sale in pressurised barrels or kegs and then dispensed directly from these. Currently used pressure vessels, such as kegs, are formed of metals such as steel or aluminium, which provide sufficient strength to resist the expansive force of the pressurised contents as well as being able to withstand the rough handling associated with the transport of these items. Historically such barrels were constructed from wood, but nowadays commercial operations use metal barrels (or kegs). Such existing barrels are both expensive to produce, heavy to handle even when empty, and impractical to repair - as they are a one-piece construction which must be totally replaced if any part thereof becomes damaged.

GB2452599 discloses a plastic keg that is formed from several separate components, each of which is lightweight but which together co-operate to provide sufficient strength to resist the pressurised contents and rough handling. The design shown therein has certain limitations and the present invention provides various improvements over that existing design.

Whilst the present invention provides a new design of pressure vessel suitable for the storage and transport of a wide variety of products and substances, it will primarily be discussed in the context of beverage (and particularly beer) handling. It is however not limited to such liquids, nor indeed to liquids alone. It could be used for any substance in any form that required pressurisation.

According to the present invention there is provided pressure vessel comprising:

- a container to hold the contents to be stored under pressure, said container having opposed ends - an opening for filling or emptying the container on one end of the container, the opening surrounded by a threaded neck formed with a buttress thread to receive a valve assembly and a sealing gasket on the side of the thread remote from the end of the container;

- a head that locates on the one end of the container and has a plurality of downwardly projecting circumferentially spaced fingers;

- a base that locates on the opposed other end and has a plurality of upwardly projecting circumferentially spaced fingers, the downwardly and upwardly projecting fingers of the head and base interfitting in a non- overlapping manner and bearing solely on the outer surface of the container;

- a sump formed in the opposed other end of the container into which a part of valve assembly extends when fitted to the neck;

- a retaining ring which locates around the interfitting fingers and holds the fingers against the outer surface of the container to hold the head, base and ring together and resist expansion of the container; and

- at least two rolling rings separate from the retaining ring that locate around the base and/or head;

- wherein the container, head, base, retaining ring and rolling rings are made from plastics material, and the head and base are provided with a handling ring in which one or more hand-hold is integrally formed to aid manual handling.

In creating the present invention, the aim was to develop a pressure vessel that could more effectively be constructed from plastics material rather than the conventional metal. The main components of the present invention are manufactured predominantly, substantially or wholly from one or more of a variety of plastics materials. The various components of the pressure vessel need not be constructed from the same material as each other. Each may be constructed from a type of material providing the optimum characteristics for its particular function. For example, the base, head and retaining ring may be formed from a higher strength material as compared to the container. The rolling rings may be formed from softer material such that noise when rolling on these rings in reduced. The threaded neck is ideally internally threaded. The extent by which the neck extends can be chosen to suit and it can be in a depression in the end of the container.

The container's main function is to hold the material, usually a liquid, for storage and transport, and must not adversely affect that material for example by tainting its contents or permitting excessive permeation between those contents and the atmosphere. Clearly such characteristics would not apply to the head, base and ring, which do not come into contact with the contents, but instead these parts must function to restrain any expansion of the container caused by the pressure of the contents, and to provide mechanical strength for handling.

The threaded neck around the opening has buttress threads which provide greater strength under pressure. The location of the gasket sealing position above the threads (i.e. furthest from the end of the container) ensures that if the valve assembly is undone when the vessel is pressurised the gas pressure is vented safely before the valve assembly is fully unthreaded and can be removed.

The hand-holds formed in the handling ring may be shaped to enable ease of grip for manual handling. They may also be formed integrally with the handling rings during moulding. This obviates the need for separate inserts to be used which in turn prevents gaps being left as possible dirt and water traps.

The container includes a sump at the end opposite the opening. In use the vessel may be stood on this end making it the bottom and liquid in the container will collect there. A part of a valve assembly such a down tube or dip tube extends into the sump. As the vessel is pressurised the height of the vessel increases slightly which can raise the lower end of such a down tube and leave an undesirable amount of ullage in the vessel. The sump minimises this loss despite expansion. The sump may be formed in a projection of the container that fits into a hole in the central region of the base (broadly equivalent to a hole in the head that locates around the opening) which can help keep the container in position when subject to the rigours of manual handling.

It could be possible for the head and base to have only one finger each, with each finger extending up to halfway circumferentially around the container. However, it is highly advantageous that the head and base each has a plurality of fingers and it has been found that at least three fingers on each is convenient, with five being particularly good. The fingers of the head and base mesh to form an inter-fitting relationship around the sides of the container. Such an inter-fitting relationship could cover some or all of the sides of the container. Depending on the strength of the container some gaps between the fingers can be left. The container can also be thickened in various areas, such as the neck to improve strength. The container may be formed by blow moulding.

The container is preferably generally cylindrical or barrel shaped with flattened ends and a curved side wall - although certain other shapes could also be employed. The container usually has an axis (of rotational symmetry) extending through the centre of each end. Both the base and head are provided with a handling ring. Those extend generally axially away from the end of the container on which the head or base are located. This handling ring is further provided with openings that form hand-holds. Such handling rings on the top and bottom of the vessel assist in its handling in a variety of ways. Kegs are frequently manoeuvred by hand and the handling rings in the present invention aid not only lifting and stacking of the barrels but also their movement. The assembled vessel may be grasped by the handling ring on the head and inclined such that it may be rolled on the handling ring on the base. The head and the base are preferably adapted to assist in the stacking of several such pressure vessels one on top of the other. The base handling ring may provide a stable stand on which the vessel may be stood, either on a flat surface or the upper handling ring of another vessel.

The head and base may be substantially the same in construction, with the possible exception of arrangements that assist in stacking. Consequently, features described in respect of one may in general apply equally to the other. The head and the base are preferably substantially the same in shape and configuration as this simplifies manufacture and allows them to function interchangeably.

The head, and/or base, may comprise a generally circular shoulder from which the fingers extend axially. Such axial extension is generally parallel to the axis of the container. The handling ring may extend in an opposite axial direction from an opposite side of the shoulder. The handling ring may also be formed from a shaped continuation of the shoulder. The handling ring will preferably be of a reduced diameter with respect to the shoulder. Except insofar as bung hole access is required, the base and head may form a complete cover to the ends of the container. However, it may be appropriate for at least a portion of the area overlying the ends (such as that within the handling rings) to be open. A projection of the container for the sump may locate in such an opening.

The fingers may take a variety of shapes and may all be different.

However, it is highly advantageous that all fingers are essentially equivalent. Preferably each finger is generally trapezoid in shape tapering towards the outer end. Preferably the fingers are shaped such that the gap between two adjacent fingers on the base exactly matches the shape of the fingers extending from the head - and vice versa.

The retaining ring is preferably generally tubular. The diameter of the retaining ring is preferably such that it may snugly engage over the fingers. The width of the retaining ring (i.e. the height of the cylinder) is preferably approximately equal to the length of the fingers.

Preferably the outer end of each finger is provided with a ridge on its radially outer surface. When the components are assembled the retaining ring and rolling rings sits snugly between the ridges on the fingers of the base section (which ridges bear on a circular edge of the retaining ring or a rolling ring) and the ridges of the fingers extending from the head section (which ridges bear on the opposite circular surface of the retaining ring or opposed rolling ring). In this way the retaining ring prevents both radial expansion of the container as well as axial extension. For axial extension to occur the head and base section would need to move apart, however the retaining ring prevents that axial separation due to the engagement of the ridges with the retaining ring and/or rolling rings.

The container may be provided with one or more suitable opening. Said one or more suitable opening, or bung hole, may be located in an end of the container. Preferably the head and/or base section do not cover at least that portion of the respective end walls. The nature and quantity of such openings depends on the nature of the contents stored therein.

Barrels and kegs are frequently transported by rolling them on their circumferential surfaces. The rolling rings provide circumferentially extending rolling surfaces upon which the pressure vessel may be rolled. The use of separate rolling rings and retaining ring facilitates manufacture, assembly and the use of different materials. The rolling rings are a softer grade of plastics material such that rolling noise is reduced. This also permits the retaining ring to be formed by extrusion of a stronger more rigid plastics material thus better resisting the effects of the internal pressure and providing the rigidity required for greater stacking heights.

To assemble the pressure vessel of the present invention, the components must be fitted together. One convenient way of achieving this is to locate the container into the base and then to engage the head on the opposite end of the container so that the fingers of the head and base inter-fit. The first rolling ring, retaining ring and second rolling ring may then be sequentially passed vertically downwards over the head section until they engage around the fingers. If, as is desirable, the fingers are provided with ridges, the parts including the more rigid retaining ring must pass over the ridges of the fingers extending upwardly from the base. Whilst the construction of the fingers should permit a sufficient degree of flexing for the fingers to move inwards so that the ridges pass beneath the retaining ring before flexing outwards to engage behind it, a snug fit between the container, base and head might prevent this. Therefore, whilst a snug fit is desirable in all other parts to prevent expansion of the container before it engages the head, base and ring, a groove or depression may be formed in the side wall to permit a sufficient degree of inward radial deformation of one set of fingers as the retaining ring/rolling rings pass thereover.

Clearly, if the components of the barrel are to be disassembled, for example for cleaning or repair, the ridges on the fingers may be depressed into the groove and then the retaining ring lifted and axially slid off the assembly.

The pressure vessel as described above may further comprise a valve assembly fitted to the threaded neck and extending through the interior of the container into the sump. Such a valve assembly may be a conventional spear and/or may be formed wholly or mostly from plastics material.

In order that it may be better understood, but by way of example only, one embodiments of the present invention will now be described in more details with reference to the accompanying drawings in which:

Figure 1 is an exploded perspective view of the various components of one embodiment of the present invention; Figure 2 is a perspective view from the side of those components assembled to form a first embodiment of pressure vessel;

Figure 3 is a plan view of the vessel of Figure 2; and

Figure 4 is a vertical section through the pressure vessel along lines X- X.

Referring to all the Figures there is shown an embodiment of pressure vessel generally indicated 10 which is assembled from a head 1 1 , a base 12, a container 13, a retaining ring 14 and two rolling rings 15a 15b. The container 13 is generally cylindrical with an upper end 1 6 provided with a bung hole 17 and a lower end 9. A filling and emptying mechanism 18 for the contents is shown and the long pipe shaft 19 extends downwards into the interior of the container 13 to reach the bottom. As seen in Figure 4 the pipe shaft 19 extends into a sump 35.

The head 1 1 and base 12 each comprise a generally circular curved shoulder region 20. From the inner edge 21 of each shoulder region 20 a plurality of fingers 22 extend axially with respect to the container 13. Each of the head and base are substantially similar and each has five fingers 22.

The internal profiles of the head and base correspond to the profile of the container 13 around which they will closely locate. As the container 13 is generally circular the profiles of the head and base 1 1 and 12 are also generally circular.

At the outer end (i.e. the end opposite the fingers) of the head 1 1 there is provided an upper handling ring 24. On the base 12 an equivalent base handling ring 25 is also provided. Handholds 28 are defined by the handling rings 24, 25 to aid manual and mechanical grasping.

The fingers 21 are in this embodiment generally trapezoid in shape tapering slightly to their free ends 29 and the shape of the fingers of the head correspond to the gaps between the fingers of the base and vice versa. This allows the fingers to closely inter-fit when the head and base are brought together.

The retaining ring 14 is generally cylindrical and is formed by extrusion. The combined width of the retaining ring and rolling rings is slightly less than the length of the fingers 22. The rolling rings provide continuous, circumferentially extending, rolling ridges with convenient surfaces upon which the assembled vessel may be rolled.

To assemble the pressure vessel, which in this instance is a beer barrel, the container 13 is located into the base 12 such that the lower end 9 of the container engages the internal surface of the base - with the curve of the container's shoulder (i.e. the area of transition between the side wall and the end wall) engaging the inside of the curved shoulder region of the base. A projection 36 on the lower end 9 in which the sump 35 is formed locates into an opening 37 in the base 12. The fingers 22 will at this point be extending upwards over the side of the container 13. The free ends 29 of each finger are provided with a ridge 30 which aligns with a circumferential groove 32 formed around the side of the container. The ridges 30 usually extend circumferentially.

The head 1 1 is then located over the upper end 1 6 of the container 13 so that the curved shoulder region 20 of the head rests upon the curved transition region between the upper end 16 of the container and the side thereof. A head opening 38 on the head 1 1 will locate around the neck 39 on the container. At this point the fingers 22 depending from the head 1 1 will locate in the spaces between the fingers 22 of the base 12. The lower rolling ring 15b may then be slid axially over the assembly until it is in position overlying the inter-fitted fingers 22. It locates adjacent the lower end of the fingers 22 depending from the head 1 1 . The retaining ring 13 may then be slid axially over the assembly until it is in position overlying the inter-fitted fingers 22 and abutting the lower rolling ring 15b. The upper rolling ring 15a may then be slid axially over the assembly until it is also in position overlying the inter-fitted fingers 22. It locates adjacent the free ends of the fingers 22 projecting up from the base 12. The retaining ring and rolling rings prevent the unintentional axial separation of the head and base as well as any radial expansion of the container 13 and fingers 22. The rolling rings and retaining rings may be provided with means to permit their interconnection prior to being engaged over the fingers as a combined unit.

An assembled vessel 10 is shown in Figure 2. This vessel may have pressurised contents introduced via means 18, which may then be sealed to store the contents under pressure and allow their transportation. The pressure within the container 13 would cause some expansion, but the component parts, which are constructed from plastics material, resist all but a small degree of expansion. This small expansion would only tend more tightly to engage the retaining ring, head and base.

As assembled this pressure vessel 10 permits handling in a way equivalent to existing kegs. For example, the vessel may be rolled on the handling rings 24, 25 or the circumferential rolling rings 15a 15b.

Figure 4 shows a vertical cross-section in which the engagement of the retaining ring and rolling rings with the ridges 30 is more easily understood. As can be seen in Figure 4, the free end 29 of the finger 22 that extends upward from the base 12 aligns with the circumferential groove 32. A ridge 30 is provided on that fee end and extends partially radially with respect to the container 13. During assembly the rolling rings and retaining ring 14 are slid axially from above (as viewed in Figure 4) over the head 1 1 . When the retaining ring and rolling rings reach the upper of the two ridges 30 the fingers 22 are resiliently deformed inwardly sufficient for them to pass thereunder. This deformation is accommodated by the circumferential groove 32. The deformation is most important for the retaining ring as the greater rigidity of this resist any radial expansion then might otherwise assist. Once the retaining ring 14 (and rolling rings) has passed to the correct position the finger 22 will flex back so that the ridges 30 locate behind the retaining ring and prevent its vertical removal - unless those fingers are again flexed deliberately inwards. At this point the corresponding ridges 30 formed on the free ends 29 of the fingers 22 depending from the head 1 1 will locate against a lower end of the retaining ring or lower rolling ring. This prevents further downward axial movement of the retaining ring 13.

The present invention provides a pressure vessel, particularly a beverage barrel or keg that may be constructed from lightweight plastics, which may be easily formed by techniques such a blow moulding, injection moulding and extrusion, yet which also provides a vessel that is strong and sturdy enough to be pressurised and handled in a similar fashion to existing metal pressure vessels.

Claims

1 . A pressure vessel comprising:

a container to hold the contents to be stored under pressure, said container having opposed ends;

an opening for filling or emptying the container on one end of the container, the opening surrounded by a threaded neck formed with a buttress thread to receive a valve assembly and a sealing gasket on the side of the thread remote from the end of the container;

- a head that locates on the one end of the container and has a plurality of downwardly projecting circumferentially spaced fingers; a base that locates on the opposed other end and has a plurality of upwardly projecting circumferentially spaced fingers, the downwardly and upwardly projecting fingers of the head and base interfitting in a non- overlapping manner and bearing solely on the outer surface of the container;

a sump formed in the opposed other end of the container into which a part of valve assembly extends when fitted to the neck;

a retaining ring which locates around the interfitting fingers and holds the fingers against the outer surface of the container to hold the head, base and ring together and resist expansion of the container; and at least two rolling rings separate from the retaining ring that locate around the base and/or head;

wherein the container, head, base, retaining ring and rolling rings are made from plastics material, and the head and base are provided with a handling ring in which one or more hand-hold is integrally formed to aid manual handling.

2. A pressure vessel as claimed in claim 1 , wherein the head has an aperture through which the threaded neck extends.

3. A pressure vessel as claimed in claim 1 or claim 2, in which the head and base each have at least 3 similar fingers.

4. A pressure vessel as claimed in claim 3, in which the head and base each have 5 similar fingers.

5. A pressure vessel as claimed in any of the preceding claims, in which the base handling ring provides a stand on which the vessel may be stood.

6. A pressure vessel as claimed in any of the preceding claims, in which the head and/or base each have a circular shoulder from which the or each finger axially extends and the handling ring of smaller diameter also extends.

7. A pressure vessel as claimed in any of the preceding claims, in which ridges are provided on an external face of each finger, which ridges engage with the ring to prevent axial displacement of the base or head.

8. A pressure vessel as claimed in any of the preceding claims, in which the head and base are substantially the same.

9. A pressure vessel as claimed in any of the preceding claims, in which a groove is formed in the side of the container to permit resilient inward radial deformation of one set of fingers during assembly of the vessel.

10. A pressure vessel as claimed in any of the preceding claims, which is a barrel or beverage keg.

1 1 . A pressure vessel as claimed in any of the preceding claims, in which the rolling rings are formed from a different plastics material to the retaining ring.

12. A pressure vessel as claimed in any of the preceding claims, wherein the sump is formed in a portion of the container that extends from the other end of the container and which locates in an opening formed in the base.

13. A pressure vessel as claimed in any of the preceding claims, further comprising a valve assembly fitted in the threaded neck and extending through the interior of the container into the sump.

14. A pressure vessel as claimed in claim 1 1 , in which the valve assembly is formed wholly or mostly from plastics material.