GB2206337A - Keystone - Google Patents

Abstract

A keystone for a beer barrel comprises a frusto-conical sealing ring (20) into which is push-fitted a separately formed plug (10) of a plastics having a density less than that of water. The plug (10) has an external flange (11) which abuts against the inner end of ring (20). The plug (10) also includes an internal tubular section (13) sealed by a tear-away removable closure (17). The tubular section (13) can be sealed with a plastic plug or tut when the closure is removed for fining the beer. During the tapping operation, the plug is driven into the barrel, where it floats to the surface of the beer. <IMAGE>

Description

PLUG The present invention relates to a plug, particularly, though not exclusively, to a keystone-type plug for a container such as a beer barrel.

Previously proposed keystones have been made from various woods and either turned or compressed to give the desired shape. This is then counter-bored and ring-cut from both sides to facilitate the fitting of the tap. This design has the following inherent faults:1. It has to be counter-bored to thin down the thickness of the wood to be broken through when the tap is driven into the tap-hole. This causes a dirt trap and any dirt or liquid collected in this recess is driven though with the tap into the beer.

2. The inner part of the plug has to be physically broken away from the outer ring on the penetration of the tap. The success of this operation cannot be ensured and depends on the accuracy of the counter-bore and ring-cuts. The force needed to achieve penetration of the tap sometimes results in the breakage of the complete keystone plug and serious leakage can occur.

3. Upon breaking the inner portion, a rough uneven area is left on the inner wall of the keystone.

It is against this inner wall that the tap has to seal and consequently, it is possible that the tap and keystone do not seal properly causing further leakage.

Current beer barrel handling procedures require that the barrels stand on their end faces rather than lie on their sides and therefore it is necessary to conduct the fining operation for beer through the tap-holes in the end of the barrel rather than through the bung-hole in the side as has been done previously.

Consequently, the keystone plug for the tap-hole must now fulfill the functions of sealing the barrel, allowing the fining operation to be conducted and allowing the tap to be inserted therein when beer is to be drawn from the barrel.

Furthermore, as the keystone is located on the top face of the barrel, it is prone to collect dirt and rain water and sediment resulting from leaking beer.

The fining operation is accomplised by driving a plastic tut or plug through the keystone into the barrel, adding the finings to the beer and resealing the hole with another plastic tut. This means that the beer is liable to contamination due to foreign matter entering the barrel. The wooden keystone is also prone to damage and failure whilst these operations are being carried out due to the critical tolerances required to achieve effective sealing and easy opening.

It is an object of the present invention to provide a design of keystone plug which obviates or mitigates these problems and so allowes the fining operation to be carried out with reduced danger of beer contamination.

According to the present invention there is provided a keystone comprising an annular outer ring having a tapered outer surface and defining a passage into which a tap may be inserted; a removable plug being located in said passage, said plug having a bore provided therein, a removable closure provided in said bore and a formation being provided on said plug so as to prevent withdrawal of said plug from said ring in one direction.

The annular outer ring is typically formed from a material which swells when wet.

In a preferred embodiment, the plug comprises a tubular body made of a resilient plastics material having a tubular portion located therein, said body and said portion being joined together at respective ends thereof and said tubular portion being provided with the removable closure.

It is preferred that the removable closure comprises an integrally formed plastic cap which can be torn away from the plug.

It is also preferred that the plug comprises a single piece integral plastics moulding, typically formed from food grade plastics and having a density less than that of water.

Conveniently, two removable closures are provided, a second closure being provided for insertion into the tubular portion after removable of the first closure.

It is preferred that the ring engaging formation comprises an outwardly projecting flange provided around one end of the plug.

The sealing ring is conveniently formed from wood conglomerate cork or a suitable plastics material e.g.

hygroscopic thermoplastics, nyl n etc.

Preferably, the end of the plastics plug fits flush with the outer end of the sealing ring, the plastics plug typically being a push fit into the sealing ring.

The two part construction of the keystone plug according to the present invention allows accurate formation of thesealing ring and so ensures a good, leak-free fit between the keystone and barrel and the keystone and tap.

By using a material which swells when wet such as wood or cork, the fit in the tap-hole and onto the tap is improved. The high friction of these materials assists in preventing accidental removal of the tap or keystone.

The use of a construction involving a body and an inner tubular portion enables the plug to act as a "U" section seal, increasing internal pressures increasing the sealing effect against the tap-hole and tap.

The present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a cross section of a plug according to one aspect ofAthe present invention and Figure 2 is a cross section of a keystone according to another aspect of the present invention, inserted into the tap-hole in a beer barrel (not shown).

Referring now to Figure 1, the plug shown therein comprises a single piece moulding of LDPE melt (20) (low density polyethylene) having a specific gravity of 0.920. The plug is in the form of a straight sided tubular body (10) having an outwardly projecting flange (11) formed around an open end (12) thereof. A second tubular section (13) located within the body (10), the periphery of an end (14) of the section (13) being connected to the end (15) of the body (10) which is remote from said open end (12). The free end (16) of the section (13) is located within the body (10). The inner surface of the section (13) is ribbed and the end (14) is sealed with a removable cap (17). The cap (17) comprises a circular disk located within the end (14) of the section (13) and connected thereto by means of a thin web of material (18) which is easily broken.A plastic plug or tut (not shown) is also provided which can be push fit into the section (13) after removement cap (17) in order to reseal the plug.

Referring to Figure 2 the keystone is formed when inserting the plug as shown in Figure 1 into a circular, frustoconical sealing ring (20). A circular bore (21) is provided in the sealing ring and the plug is a push fit into this bore from the narrow end of the ring (20). The closed end of the plug fits generally flush with the wide end of the sealing ring and the flange (11) engages the narrow end of the ring (20).

The completed plug is then driven into the tap hole of a beer barrel after filling with beer. The plug engages the ring along the whole length thereof and so provides support, and makes the ring less prone to breakage when being driven into the barrel.

To carrying out the fining operation, the cap (17) is removed by snapping the web (18) and the finings are added through the plug. When this is done, a plastic plug or tut (not shown) is inserted into the now open section (13) to reseal the plug, the ribbing serving to assist in retention of the tut.

When the tap (not shown) is to be inserted in to the tap-hole (25), the barrel is lying on its side with the tap-hole below the surface of the beer. The end of the tap is placed over the plug and hammered home.

This achieves removal of the plug which is driven into the barrel and insertion of the tap into the keystone ring. The plug being less dense than water floats to the surface and can be removed when cleaning the barrel.

The flush fitting of the closed end of the plug with the sealing ring means that no dirt or rain water can collect in the plug and be driven into the beer.

Furthermore, the resilient nature of the plastic plug allows any irregularities in the keystone ring or tap to be accomodated while maintaining an effected seal.

The use of a food grade plastics moulding means that high reproducability of the plug dimensions can be achieved with little chance contaminating the beer due to contact.

Claims (11)

CLAIMS:

1. A keystone comprising an annular outer ring having a tapered outer surface and defining a passage into which a tap may be inserted; a removable plug being located in said passage, said plug having a bore provided therein, a removable closure provided in said bore and a formation being provided on said plug so as to prevent withdrawal of said plug from said ring in one direction.

2. A keystone as claimed in claim 1, wherein the annular outer ring is formed from a material which swells when wet.

3. A keystone as claimed in claim 1 or 2, wherein the plug comprises a tubular body made of a resilient plastics material having a tubular portion located therein, said body and said portion being joined together at respective ends thereof, and said tubular portion being provided with the removable closure.

4. A keystone as claimed in any preceding claim, wherein the removable closure comprises an integrally formed plastic cap which can be torn away from the plug.

5. A keystone as claimed in any preceding claim, wherein the plug comprises a single piece integral plastics moulding having a density less than that of water.

6. A keystone as claimed in any preceding claim, wherein two removable closures are provided, a second closure being provided for insertion into the tubular portion after removal of the first closure.

7. A keystone as claimed in any preceding claim, wherein the ring-engaging formation comprises an outwardly projecting flange provided around one end of the plug.

8. A keystone as claimed in any preceding claim wherein said ring is formed from wood, conglomerate cork or a suitable plastics material.

9. A keystone as claimed in any preceding claim, wherein the end of the plug fits flush with the outer end of the ring.

10. A keystone as claimed in any preceding claim, wherein the plug is a push fit into the ring.

11. A keystone substantially as hereinbefore described with reference to the accompanying drawings.