Field of the Invention

The invention relates generally to bungs and airlocks for use with gas-producing reactions, and has particular relevance in the field of fermentation in the production of alcoholic beverages.

Background to the Invention

Fermentation is an essential step in the production of alcoholic beverages which involves the conversion of sugars into alcohol and carbon dioxide. Every 'home- brewing' process, such as wine or beer making, requires a user to seal a mixture (the 'wort' in the case of beer brewing) in a fermentation vessel to allow this reaction to occur. In order that the carbon dioxide produced does not cause damage to the fermentation vessel during this process, an airlock arrangement is typically provided which releases the carbon dioxide in a controlled manner whilst preventing air or other airborne contaminants from entering the vessel.

Popular and well-known prior art comprises a two- or three-part arrangement. Firstly, a bored rubber bung, which is usually tapered, is inserted into a top end of the fermentation vessel. An airlock is inserted into the wider end of the bung, with the narrower end of the bung being inserted into the fermentation vessel. The airlock either takes the form of an 's-type' tube with such a configuration as to allow a small quantity of liquid to settle in one part of the tube and thus form a seal between the two gaseous environments (that within the fermentation vessel, and the external environment), or a two-part, normally cylindrical arrangement, which acts to provide the same when assembled. In both cases, as pressure builds within the vessel due to the production of carbon dioxide, the liquid within the airlock is forced to allow gas bubbles to escape from within the vessel, whilst preventing gases and other airborne contaminants from entering the vessel. Both such airlocks are usually transparent, which permits the ability to monitor the fermentation process easily as it unfolds within the airlock, and both such airlocks involve a 'cap', of sorts, which acts to substantially prevent dust and other similar airborne contaminants from entering the system (in the case of the two-part arrangement, one of the two pieces of the airlock system also acts as such a dust-preventing cap).

However, these are multi-component arrangements which are often difficult for a 'home brewer' to assemble and use correctly. They also prove difficult to clean because of their number of small and inflexible parts, which is of particular concern given the strict levels of hygiene that are required for successful brewing of alcoholic beverages. The number of connections between components in these known arrangements also creates a risk of unwanted gas exchange from the fermentation vessel to the outside environment and vice versa, and also provides a large number of contact points at which bacteria may form.

A further disadvantage of these existing arrangements is that the bung and airlock, once they are both in place, usually protrude from the top of the vessel by a few inches. This results in an arrangement which is prone to being knocked out of place, and one which restricts the available storage options for the fermenting system once assembled. Minimising the amount of space that a fermentation vessel takes up is of great importance given that these vessels are usually required to be left, with minimal movement, for days or weeks at a time.

Other, less well-known, prior art arrangements seek to resolve some of these problems. Such inventions involve a bung which is capable of retaining an amount of fluid, such that the bung itself forms part of the airlock. Whilst such prior art successfully reduces or mitigates some of the problems listed, they fail to address all of the problems, or present a new set of problems in respect of the portion functioning as the bung or the portion functioning as part of the airlock, or both. Prior art arrangements which are intended to be constructed of opaque materials such as metal, wood or glazed stoneware remove or significantly hinder the ability to easily monitor the fermentation process unfolding within the airlock, which is a disadvantage relative to the popular arrangements. Prior art

arrangements which are intended to be constructed of inflexible materials such as glass or poly-ethylene hinder the ability of the device to form a robust, airtight seal able to withstand the pressure built-up within the receptacle during fermentation relative to the comparatively rubbery, elastic material of the bung used in popular arrangements.

Prior art arrangements which could conceivably be formed of a material which is both transparent and suitably elastic or rubbery (even if these materials were not originally contemplated for use with the design), present other disadvantages. One known arrangement provides a bung portion which features a cylinder with a series of protruding ridges and indentations intended to press against the inner wall of the fermenting receptacle and in so-doing provide a seal. Such a device is not as suitable as the tapered portion of the bung used in popular arrangements for the reason that it poses a risk of being incapable of forming a sufficiently tight seal to withstand the pressure built-up within the receptacle during fermentation, and for the reason that it does not allow for small variations in the diameter of the orifice in the way that the popular bung does, which tapers from a larger diameter to a smaller diameter. Another known arrangement provides a passageway for gas from the bottom of the device, via a curved tube, to a position below the, in use, liquid level in the bung's reservoir. If made of a rubbery, transparent plastic or other similar material, this arrangement is not only difficult to manufacture via standard plastic-moulding techniques (such as injection-moulding or over- moulding) by reason of its curved integral tube, but the absence of a cap exposes the liquid and thus, the system, to airborne contamination in a way that the popular arrangements do not. Yet another known invention provides an airlock which is substantially the same in concept as the popular two-part arrangement, but one of these parts has a tapered portion and thereby also acts as the bung. This particular arrangement, however, additionally provides openings near the top of the part which doubles as the bung, which serve the function of permitting the eventual escape of air from the system. These openings are unnecessary since the same function can be performed through an interaction between the two pieces, instead of needing to create holes through one of the pieces. Indeed such openings present a disadvantage in manufacturing were the device to be made of a flexible, transparent material via standard moulding processes, given the additional tools, time and expense that the construction of such moulds would require over those used to create a 'solid' outer surface. The arrangement was not intended to be formed of such materials, and indeed the processing of such materials was not established at the time of invention of this particular

arrangement.

It is therefore an object of the current invention to alleviate at least these problems.

Summary of the Invention

A bung for providing an airlock between a chamber and an environment external to the chamber, the chamber having at least one orifice into which the bung, in use, is secured; the bung providing a side outer surface which provides a tapered portion configured to abut against the circumference of said orifice; the invention further providing a removable cap which overlays, is inserted into, or otherwise connects with, the bung in such a way as to substantially prevent dust and similar airborne contaminants from entering the bung; the bung further being capable of retaining an amount of fluid suitable to form a seal between the chamber and the external environment; the bung being able to provide said seal with said amount of fluid either independently or in conjunction with a removable cap; the bung further comprising a passageway which extends internally, said passageway comprising at least two openings; an inner surface of said passageway towards an, in use, top end of the bung being tapered inwards; the bung being made wholly, or in part, of a material which is rubbery or elastic, and which is resilient enough to create a seal when inserted into the chamber and yet to return to its original shape when removed; said material also being transparent, translucent or otherwise substantially see-through.

This configuration is particularly advantageous because it provides a bung for abutting, and providing a seal about, the rim of an orifice of a chamber, with an integral airlock, so that a separate airlock device is not required to be inserted into the bung. The bung is also compact. The bung also provides for intuitive installation and removal from a chamber such as a demijohn or carboy.

This configuration also provides a bung which is straightforward to clean because there is only a single component with a passage running there through. Being able to effectively clean such a device is particularly important because

equipment used for brewing or other similar processes must be sterilised before use. The lack of multiple pieces and therefore joins between those pieces means that the risk of unwanted gas exchange between the chamber and the external environment is minimised or prevented, and the risk of contamination from bacteria forming at contact points is reduced. The bung also minimises the size of the chamber when inserted in comparison to existing bung and airlock

arrangements. Less space is therefore required for storage of the chamber in which the bung is inserted.

The advantages of a rubbery, elastic material combined with transparency permits the bung the ability to be tightly inserted into the orifice of the chamber whilst permitting the user the opportunity to view and monitor the fermentation process unfolding within the bung.

The cap also provides advantages in terms of hygiene and cleanliness of the system, in that it is configured to protect the system from dust and other airborne contaminants.

Preferably, said outer surface and the passageway are formed of a single piece. This configuration is particularly advantageous because it provides a single piece bung which retains fluid for forming a seal between the chamber and external environment whilst also providing a seal between the bung and the orifice of the chamber. A separate component is therefore not required for retaining the fluid. Further, where the passageway and outer surface are of separate pieces, there is a possibility, given the inherent malleable plasticity of the bung, that the

passageway can come away from the bung; a unitary construction dispenses with this issue because there is no longer any join between the pieces.

Preferably, the bung is formed as a single piece and said passageway is a bore into said single piece and is spaced from the outer surface such that the outer surface surrounds the passageway. This configuration is particularly

advantageous because it improves the protection of the passageway because the structure of said passageway is enclosed within the single piece bung. Spacing the outer surface such that it surrounds the passageway also allows the bung to be effectively inserted into an orifice of a chamber. Also, because the bung is formed as a single piece, there is no assembly required, which is more straightforward for the user.

Optionally, the passageway has a diameter which is greater towards the, in use, top end of the bung than towards the, in use, bottom end of the bung. Providing a passageway with a diameter which is greater towards the, in use, top end than towards the, in use, bottom end allows gas to more easily escape from the chamber when the pressure has reached a particular level. This configuration also improves the ease with which a cap may be inserted into the opening at the top end. It is preferable to increase the diameter towards the top end of the bung rather than increase the overall diameter of the passageway to maintain the structural integrity of the bung and to maximise the available volume for retaining fluid.

The bung is comprised of a transparent or near-transparent material. A

transparent or near-transparent bung allows a user to view and monitor the passageway and fluid retained in the passageway. Activity of a fermentation reaction can therefore be more straightforwardly monitored without requiring an airlock which extends substantially above the chamber.

Preferably, the fluid retaining portion of the passageway is positioned within the bung such that, in use, when the bung is inserted into a chamber, the fluid retaining portion is viewable above the chamber. Positioning the fluid retaining portion of the passageway at a viewable height above a chamber in use, allows a user to straightforwardly and accurately monitor the integrity of the seal between the chamber and external environment as well as the activity of any reaction inside the chamber, such as fermentation.

The invention provides an airlock arrangement comprising a bung in accordance with any of the preceding aspects, and further provides a removable cap which overlays, is inserted into, or otherwise connects with, the bung in such a way as to substantially prevent dust and similar airborne contaminants from entering the bung and therefore the chamber.

Preferably, the cap comprises a projection which may be inserted into said passageway such that an end of the projection is submerged in the fluid retained in said passageway, wherein said projection cooperates with the passageway to form a seal between a chamber into which the arrangement is inserted and the external environment.

This configuration is particularly advantageous because the two-piece

arrangement provides a seal between a chamber and the external environment so that a separate bung and airlock are not required. The projection of the cap and passageway forms a seal which is more compact than conventional, discrete bungs and airlock devices.

Preferably, said cap has an outer surface which is complimentary in shape to the top end of the bung. Providing a cap with a shape complimentary to that of the top end of the bung improves the barrier that the cap provides to prevent airborne contaminants from entering the bung and chamber. This configuration also minimises the risk of the cap becoming dislodged if knocked by a user.

Brief Description of the Drawings

In the drawings:

Figure 1 shows a side on view of a preferred embodiment of the invention in a disassembled configuration.

Figure 2 shows a perspective view of the embodiment of Figure 1 in a disassembled configuration.

Figure 3 shows a side on view of the embodiment of Figures 1 and 2 in an assembled configuration.

Detailed Description of the Embodiments

An improved bung is shown in Figure 1 and is referenced generally as 1 . The bung 1 is configured to act as an airlock between a chamber (not shown) and an environment external to the chamber, for use in processes such as fermentation in the production of alcoholic beverages, and in other gas-releasing reactions which require an airtight seal between the reaction chamber and the external environment yet allow for the release of gas from the reaction vessel.

The bung 1 comprises a top end 3, a bottom end 4 and a side outer surface 5 which is provided between the top and bottom ends. The side outer surface 5 contains a tapered portion to abut against the circumference of the orifice of a chamber. In a preferred embodiment, the bung 1 has a substantially circular cross-section, allowing the bung 1 to be inserted into and to abut against the rim of a chamber with a circular orifice. The side outer surface 5 may alternatively be faceted. The bung 1 further comprises a passageway 2 which extends internally between the top end 3 and the bottom end 4. At least two openings, such as 6 and 7, are provided to allow gas to pass through the bung 1 , in use, from a chamber to the external environment. The passageway 2 also comprises a number of turns, such as 8 and 9 which, in use, retain an amount of fluid suitable to form a seal between the chamber and the external environment. The bung 1 thereby acts as a fluid retaining vessel to provide an airlock preventing gas exchange between the chamber and the external environment, unless the pressure of the gas within the chamber reaches a level where the bung 1 is forced to allow a small amount of gas to escape.

In an alternative embodiment, the outer surface 5 which, in use, abuts against the circumference of a chamber orifice, and the passageway 2, are both formed as a single piece so that the seal around the circumference of the chamber orifice and the seal between the chamber and the external environment are integrally formed, both seals therefore being effected by a single piece bung 1 . The bung 1 is preferably formed as a single piece and the passageway 2 is a bore into the single piece bung 1 , with the passageway 2 being spaced from the outer surface 5 such that the outer surface surrounds the turns 8, 9 of the passageway 2.

The bung 1 is comprised of food-friendly material, such as a flexible plastics material or silicone rubber, which is resilient enough to create an airtight seal when inserted into a chamber and yet elastic enough to return to its original shape when removed and not in use. The bung 1 may be comprised of an alternative material having these characteristics or a combination of plastics material and another material.

The configuration of the bung 1 minimises the amount of space required above a chamber. In comparison to existing multiple component bungs and airlocks, the improved bung 1 reduces the amount of clearance required above a chamber to as little as 3 to 4 centimetres. Because it is configured to be inserted into the same orifices as an existing 'airlock-less' bung, the improved bung 1 has a similar shape and size. For use in conjunction with a standard demijohn, the width of the bung 1 preferably tapers from approximately 31 mm at its widest (towards the top end 3) to approximately 28mm (towards the bottom end 4). The bung 1 tapers in such a way that a tight fit is ensured when inserted into the opening of a chamber such as a demijohn, and so that the seal provides sufficient resistance against the bung 1 'popping out' of the chamber due to vigorous gas-release. The height of the bung 1 when used in conjunction with a standard demijohn is preferably approximately 40mm allowing for approximately 10mm of the bung 1 to descend below the top of the chamber.

The bung 1 preferably has a tapered configuration, wherein the diameter of the bung 1 is wider towards the top end 3 and narrows towards the bottom end 4. A tapered configuration allows the bung 1 to be securely inserted into orifices of varying size to create an airtight seal between the outer surface 5 of the bung 1 and the rim of the orifice. The outer surface 5 is not dictated by the configuration of the passageway 2 so that the bung 1 can be of a shape which is suitable to be inserted into a chamber such as the circular neck of a demijohn, carboy or wine bottle etc.

The turns 8, 9 may comprise bends, corners or twists in the passageway 2, which may extend in a number of possible directions. A configuration different to that shown in the figures may be provided, although the configuration of the passageway 2 shown is preferable because a larger volume of fluid can be retained in the passageway 2 without jeopardising the structural integrity of the bung 1.

The passageway 2 preferably has a constant diameter between openings 6, 7 and even more preferably comprises a circular bore so that gas can

straightforwardly flow through the bung 1 and so that fluid does not become trapped within the passageway 2, which might harbour bacteria or other contaminants. However, in an alternative embodiment, the passageway 2 may have an irregular diameter or a constant diameter which is not circular in cross section.

Preferably, the passageway 2 extends through the central axis of the bung 1 . The passageway 2 has a diameter which is larger towards the top end 3 than towards the bottom end 4 of the bung 1. As shown most clearly in Figure 1 , the

passageway 2 is preferably comprised of two portions: a first portion 12 which extends upwardly from opening 7 at the bottom end 4 of the bung 1 ; and a second portion 13 which extends from opening 6 at the top end 3 of the bung 1 towards the bottom end 4 of the bung 1. The first portion 12 preferably has a constant diameter to maintain the structural integrity of the bung 1 . For this same reason, the first portion 12 may preferably be of a smaller diameter than conventional passageways of airlocks. The second portion 13 preferably has an inner surface 14 which tapers inwards towards the central axis of the bung 1 and meets the top end of the first portion 12, which improves stability and manufacturability when compared with a cylindrical arrangement involving vertical walls. An outer surface 15 of the second portion 13 is tapered away from the central axis of the bung 1 such that the second portion 13 forms a cup-like configuration for retaining fluid, for allowing the straightforward insertion of a cap at the top end 3 of the bung 1 , and for improved manufacturability over an arrangement with vertical walls. The first 12 and second 13 portions are

preferably integrally formed. In alternative embodiments, either one, or both, of the portions may have a constant or irregular diameter. In one particular alternative embodiment, the first portion may also have a tapered configuration which corresponds to the tapering of the inner surface 14 of the second portion 13.

Preferably, the openings 6, 7 are both located on the central axis of the bung 1 at or near the top 3 and bottom 4 ends and the passageway 2 has a uniform shape around the central axis of the bung 1 .

In order for a user to be able to view the passageway 2 and monitor the amount of gas which bubbles through the fluid retained in the passageway 2, the bung 1 is comprised of a transparent or near-transparent material. Being able to view the activity of an airlock is important during fermentation so that a user can determine when fermentation has begun and ended and also how vigorous the fermentation reaction is - other steps in the process of making an alcoholic beverage may be affected and altered depending on the activity viewed in the airlock. The preferred configuration allows this to happen without having to provide a separate airlock device on top of a pre-existing bung. To further improve the user's view of the passageway 2, the top end 3 of the bung 1 preferably has a curved configuration so that a clear view of the passageway 2 is available from various viewing angles. In an alternative embodiment, such as that shown in the drawings, the top end 3 is planar.

To further improve the observability of the passageway 2, the passageway 2 is preferably positioned within the bung 1 such that, when the bung 1 is inserted into an orifice of a chamber in use, the entire passageway 2 or a substantial part of the passageway 2 sits above the rim of the chamber. However, in alternative embodiments, a substantial part of the passageway 2 may sit below the rim of the chamber and the configuration of the passageway 2 may be such that the activity of the airlock can be monitored from above, or even through transparent walls of, a fermenting receptacle.

In a preferred embodiment, the bottom end 4 of the bung 1 is planar. This configuration maximises the compatibility of the bung 1 with various types of chamber.

The bung 1 may be adapted, scaled up or down or otherwise modified to be compatible with a varied range of gas-releasing receptacles.

In a preferred embodiment, the bung 1 is produced as a single piece, since this ensures that the potential for moulding 'seams' to impair the sealing ability of the bung 1 is removed.

Whilst it is preferred that the bung 1 is formed as a single piece through which the passageway 2 is bored, in an alternative embodiment the bung 1 may comprise more than one piece.

An airlock arrangement may also be provided which incorporates a bung 1 in accordance with any of the preceding aspects and embodiments, and a cap which is shown in the drawings and is referenced generally as 10. The cap 10 is configured to be positioned at the top end 3 of the bung 1 for preventing airborne contaminants from entering the bung 1. The cap 10 preferably comprises a projection 11 which, in use, is inserted into the passageway 2 of the bung 1 . In an embodiment where the bung 1 has more than one opening at the top end 3, the cap 10 may comprise a plurality of projections. In a preferred embodiment, projection 11 is hollow and has a constant diameter, e.g. is circular in cross-section, which, in use, is inserted at the top end 3 of the bung 1 such that the wall of the projection 11 surrounds the first portion 12 and inner surface 14 of the second portion 13 of the passageway. The projection 11 , when inserted, rests between inner 14 and outer 15 surfaces of the second portion 13 of the passageway 2. In this embodiment, the cap 10 plays an essential role in forming a seal between a chamber and the external environment. As shown in Figure 3, a bottom end of the projection 11 is submerged in the fluid retained by the passageway 2 to create the seal. In use, gas escaping from the chamber passes through the first portion 12 of the passageway 2 and then through the second portion 13 of the passageway 2, firstly between the inner surface 14 of the second portion 13 and the projection 11 of the cap 10, and then between the outer surface 15 of the second portion 13 and the projection 11 .

In a preferred embodiment, a portion of the passageway which is formed between openings 6, 7 of the bung 1 is substantially straight and has a substantially uniform cross-section, such that a clear line of sight is formed between openings of said portion of the passageway. This is more straightforward to manufacture than other arrangements in which said portion of the passageway is either curved, does not have a uniform cross-section, or does not have a clear line of sight between the openings.