GB2244985A - Keystone - Google Patents

Abstract

A keystone with improved feel when tapping has an outer ring 10 which is engaged, in use, in a barrel tap hole, and an inner plug 12 which is sealingly fitted into the outer ring 10. The inner plug 12 includes a sleeve 16 whose outer surface is sealingly engaged with the inner periphery of the outer ring 10. A transverse wall 18 closes the sleeve 16 and has, on its inwardly facing surface, at least one rib, preferably a pair of ribs 24 arranged in cruciform fashion. <IMAGE>

Description

KEYSTONE This invention relates to a keystone for closing the tap hole of a beer barrel, cask, keg or the like (hereinafter simply referred to as "barrel").

It is an object of the present invention to provide an improved keystone.

According to the present invention, there is provided a keystone comprising an outer ring having an outer periphery which is adapted to be engaged in a tap hole of a barrel (as hereinbefore defined), and an inner plug which is adapted to be sealingly fitted into the outer ring and which can be knocked out of the outer ring during a tapping operation, said inner plug comprising a sleeve whose outer surface is sealingly engageable with the inner periphery of the outer ring, and a transverse wall closing the sleeve, the transverse wall having, on a side of the latter which faces inwardly of the barrel in use, at least one rib integrally formed therewith.

The provision of at least one rib integrally formed with the transverse wall improves the "feel" when the inner plug is knocked out during a tapping operation.

Most preferably, said at least one rib takes the form of a pair of ribs arranged in cruciform fashion.

In a convenient embodiment, the inner plug has an externally tapered flange which engages, in use, against an inner end (relative to the barrel) of the outer ring to prevent the inner plug from being blown out in service, the external tapering on the flange serving to assist in positive alignment when fitting the keystone into the tap hole of the barrel.

Preferably also, the transverse wall is provided adjacent the end of the outer ring which faces outwardly relative to the barrel so that a portion of the sleeve of the inner plug defines a shallow recess in the outer end of the inner plug, the shallow recess preferably having a side wall which tapers inwardly towards the transverse wall defining the base of the recess. Such a shallow recess is of a diameter which is of a size to receive and assist in correct location of a tap during a tapping operation.

Preferably, at least one of the inner and outer peripheral surfaces of the outer ring and the outer periphery of the sleeve is/are ribbed to assist in sealing. Whilst the outer ring preferably has an outer periphery which is frusto-conically tapered to a slight extent, the inner periphery of the outer ring and the outer periphery of the sleeve are preferably parallel sided.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawing, in which: Fig. 1 is a side view of a keystone according to one embodiment of the present invention, Fig. 2 is a axial section through part of the keystone illustrated in Fig. 1, and Fig. 3 is an underneath plan view of the part of the keystone illustrated in Fig. 2.

Referring now to the drawing, the keystone comprises an outer annular ring 10 which is injection moulded and an inner plug 12 which is shown in more detail in Figs 2 and 3.

The outer ring 10 has an outer periphery which tapers inwardly slightly from its outer end to its inner end (ie from its top end and its bottom end as illustrated in Fig. 1). The outer periphery of the outer ring has fnne ribbing thereon which is intended to improve the fit and seal between the outer ring and the wall of the tap hole in a beer barrel. The inner periphery 14 of the outer ring 10 is likewise ribbed.

The inner plug 12 is injection moulded out of polypropylene and comprises a relatively thin sleeve 16 of circular cross section with integrally formed transverse wall 18 which closes the sleeve 16 adjacent the outer (upper, as viewed in Fig. 2) end of the latter.

The sleeve 16 and wall 18 thereby define a relatively shallow, outwardly presented recess 20 having a peripheral wall which tapers inwardly towards the base of the recess 20, ie towards the transverse wall 18. The outer periphery of the sleeve 16 is parallel sided except for an abutment flange 22 which is integrally formed at the inner (lower, as viewed in Fig. 2) end of the sleeve 16. The outer periphery of the flange 22 tapers downwardly and inwardly as viewed in Fig 2. The sleeve 16 has a ribbed outer periphery and is a push fit within the outer ring 10. However, the flange 22 is of a size such that it will not fit within the outer ring 10 and so acts as a stop to prevent the inner plug 12 from being blown out of the outer ring when pressure develops within the beer barrel in use. The tapered outer periphery of the flange 22 assists in locating the keystone within the tap hole of the barrel. The shallow recess 20 with tapered peripheral wall is of a diameter such that it receives the tap and assists in providing positive location of the tap at the start of a tapping operation.

The transverse wall 18 is relatively thin, but is provided with a cruciform rib arrangement 24 on its underside as viewed in Fig. 2, namely on the side of the wall 18 which faces inwardly of the beer barrel. The cruciform rib arrangement 24 is relatively deep and provides a pleasingly solid "feel" to the wall 18 when the inner plug 12 is knocked out of the outer ring 10 during a tapping operation. The cruciform rib arrangement 24 also strengthens the transverse wall to prevent inadvertent breakage of the wall 18 during a tapping operation.

Claims (8)

1. A keystone comprising an outer ring having an outer periphery which is adapted to be engaged in a tap hole of a barrel (as hereinbefore defined), and an inner plug which is adapted to be sealingly fitted into the outer ring and which can be knocked out of the outer ring during a tapping operation, said inner plug comprising a sleeve whose outer surface is sealingly engageable with the inner periphery of the outer ring, and a transverse wall closing the sleeve, the transverse wall having, on a side of. the latter which faces inwardly of the barrel in use, at least one rib integrally formed therewith.

2. A keystone as claimed in claim 1, wherein said at least one rib takes the form of a pair of ribs arranged in cruciform fashion.

3. A keystone as claimed in claim 1 or 2, wherein the inner plug has an externally tapered flange which engages, in use, against an inner end (relative to the barrel) of the outer ring to prevent the inner plug from being blown out in service, the external tapering on the flange serving to assist in positive alignment when fitting the keystone into the tap hole of the barrel.

4. A keystone as claimed in any preceding claim, wherein the transverse wall is provided adjacent the end of the outer ring which faces outwardly relative to the barrel so that a portion of the sleeve of the inner plug defines a shallow recess in the outer end of the inner plug.

5. A keystone as claimed in claim 4, wherein the shallow recess has a side wall which tapers inwardly towards the transverse wall defining the base of the recess.

6. A keystone as claimed in any preceding claim, wherein at least one of the inner and outer peripheral surfaces of the outer ring and the outer periphery of the sleeve is/are ribbed to assist in sealing.

7. A keystone as claimed in any preceding claim, wherein the outer ring has an outer periphery which is frusto-conically tapered to a slight extent, the inner periphery of the outer ring and the outer periphery of the sleeve are parallel sided.

8. A keystone substantially as hereinbefore described with reference to the accompanying drawing.