GB2159502A

GB2159502A - Plastic keystone

Info

Publication number: GB2159502A
Application number: GB08513107A
Authority: GB
Inventors: Thomas Arthur Carr
Original assignee: IMI Cornelius Inc
Current assignee: Cornelius Inc
Priority date: 1984-06-02
Filing date: 1985-05-23
Publication date: 1985-12-04
Also published as: GB2159502B; GB8513107D0

Abstract

A plastic keystone for a beer cask comprises a tapered annular member having an inwardly directed flange 21 in the middle region, inner ribs 27 extending towards the narrow end of the keystone and an inner annular member 22 extending towards the wider end of the keystone, the inner member having an inner tapered surface to accept a tap or tap body with a series of springy ribs 26 between the inner outer members. The member 22 may have a section 23 extending axially towards the narrow end of the keystone. Preferably there is provided a rupturable diaphragm or displaceable plug 25 inside the keystone. <IMAGE>

Description

SPECIFICATION Keystone This invention relates to keystones and has particular reference to disposable plastic keystones.

A beer cask has essentially two holes, one in the flat end known as the keystones bush, the other in the curved centre belly portion of the cask known as the shive bush. A dispensing cock or tap is eventually inserted in to the keystone bush. A keystone is hammered in to the keystone bush and may be regarded as a wooden plug having a central thinner region which can be pierced by hammering in the dispensing cock or tap.

Although the majority of keystones are wooden, plastic keystones including an integral rupture diaphragm are known.

By the present invention there is provided a keystone comprising a frusto-conical annular member having a tapered outer surface adapted to engage the keystone bush of a beer cask, a centrally located inwardly directed annular flange, an inner annular ring integral with the flange spaced from the frusto-conical annular member and extending towards the wider end of the keystone, the inner annular ring having an inner surface adapted to receive a member passing therethrough.

The inner annular ring may have an extension extending towards the narrower end of the keystone. The internal diameter of the extension may be greater than the internal diameter of the ring extending towards the wider end of the keystone so as to form a step in the bore of the keystone.

The inner surface of the inner annular ring may have a larger diameter towards the wider end of the keystone.

The inner annular ring may be connected to the outer annular member by a plurality of integral resilient ribs. There may be provided a plurality of inwardly directed radial ribs extending longitudinally of the keystone from the flange towards the narrower end of the keystone. The inner annular ring may have an inner diameter smaller than that of the annular flange.

There may be provided obturating means within the keystone. The obturating means may comprise a disk located within the flange and obturating the inner annular ring. Alternatively the obturating means may comprise a diaphragm integral with the keystone and adapted to be broken by the insertion of a member through the keystone.

Preferably the length of the tapered portion of the inner annular member is between one quarter and one half of the length of the keystone.

There may be provided a member adapted to be inserted through the keystone. The member comprising a tapered body adapted to engage, in use, the inner taper of the inner annular ring. The member may have a coarse and/or fine filter adapted to filter beer passing through the member. The member may have an enlarged diameter portion adapted to receive a fitting to connect it, in use, to a suitable beer dispense system.

The member may be of a plastics material or stainless steel and the coarse filter may comprise an apertured tube located on the inner end of the member. The inner end of the member is adapted to pass through the keystone.

By way of example, embodiments of the present invention will now be described with reference to the accompanying drawings, of which: Figure 1 is a cross section of a keystone Figure 2 is a plan view of Figure 1, Figure 3 is an underneath view of Figure 1, Figure 4 is a cross-sectional view of a member, Figure 5 is a sectional view along the line A-A of Figure 4, Figure 6 is a cross-section of an alternate form of keystone and obturator and Figure 7 is a view along the line of arrow VII with the obturator removed.

Referring to Figure 1. This shows in cross-section a keystone having an outer tapered wall 1 which is adapted to engage, in use, the keystone bush of a beer cask. The outer wall 1 may be smooth or may be serrated and tapered at an angle such that when driven in to the keystone bush it will lock in the keystone bush. Typically the angle would be in the range 3 - 6". Within the outer tapered wall 1 there is centrally located an inwardly directed annular flange 2. Extending from the annular flange 2 towards the narrower diameter end 3 of the keystone are a series of inwardly directed longitudinally extending ribs 4.

Extending upwardly, as shown in Figure 1, towards the larger diameter end 5 of the keystone is an annular ring 6. The inner annular ring has an internal tapered surface 7 which has a wider internal diameter at the larger end 5 of the keystone. Between the annular ring 7 and the outer wall 1 are a plurality of radial spring ribs 8.

The flange 2 is provided with an internal step 9 and, if required, a blanking disc may be held in the keystone against the flange 9. The provision of the ribs 4 reinforces the lower region of the wall 1 and the provision of the spring ribs 8 enhances the engagement of the keystone in the keystone bush. By providing resilience in the ribs 8 there is less likelihood of the keystone disengaging from the keystone bush.

As the inner flange 7 has only a relatively short tapered surface it is easier to disengage any cock, tap, or other member which is inserted in to the keystone during dispensing of the contents of the beer cask.

Referring to Figures 4 and 5 these show a plastics member particularly suitable for location in the keystone. It will be appreciated that the member may be formed of stainless steel.

The plastics member comprises a plastics moulding 10 having a tapered portion 11 and a cylindrical portion 12. Extending beyond the tapered portion 11 away from the cylindrical portion 12 is a cruciform member 13 which is intergral with the whole body. Four holes 14 provide connection betweed the inner passageway 15 of the member and the outside. A tube 16 having a series of aperture 17 therein is slipped over the cruciform member 13. The end cap 18 secured by a screw 19 holds the tube 16 in position.

Within the bore of the cylindrical portion 12 there may be located a proprietary fitting which may be a quick release fitting so that the beer cask may be readily connected to the dispense system of a public house.

The keystone may be provided with an integral diaphragm located in the region of the annular flange 2 or may be provided with a seperate disk abutting the annular shoulder 9.

In the embodiment illustrated in Figures 6 and 7 the outer frusto-conical member 20 is provided with an inner ring 21 from which there extends an inner annular member having an upper portion 22 and a lower portion 23. The inner diameter of the lower portion 23 is less then that of the portion 22 in the region of the ring 21 and there is provided an internal step 24 against which may be abutted a disc like obturator 25. The obturator is pushed into the keystone from the lower end.

A series of ribs 26, 27 interconnect the frustoconical member 21 with portions 22 and 23.

In use the keystone is installed in the keystone bush at the brewery. The keystone is simply hammered in to the keystone bush in the conventional way. The integral diaphragm or blanking plug prevents escape of beer through the keystone. The cask is then delivered to the public house and installed on suitable supports.

When required the member 10 is hammered in to the keystone rupturing the diaphragm or displacing the blanking plug. The member 10 is secure when the tapered portion 11 is located in the taper 7 by friction. It will be appreciated that the member 10 is provided with a valve of some kind and the member 10 may even be a conventional beer tapping cock.

When it is desired to remove the member 10 it is simply hammered sideways to release the member 10 from the tapered portion 7 of the keystone. The spring members 8 permit ready removal of the member 10 whilst gripping it during normal use.

The member 10 may be made of metal or plastics material. The keystone is preferably of a plastics material such as high density polythene. The keystone may be disposable and is removed from the keystone bush at the brewery and replaced by a new keystone. The member 10 is re-useable and is simply connected to the beer lines in the public house, preferably by way of a quick release valve.

Claims

1. A keystone of plastics material including a frusto-conical annular member having a tapered outer surface adapted to engage the Keystone bush of a beer cask, a centrally located inwardly directed annular flange, an inner annular ring integral with the flange spaced from the frusto-conical annular member and extending towards the wider end of the keystone, the inner annular ring having an inner surface adapted to receive a member passing therethrough.

2. A keystone as claimed in Claim 1 in which the inner annular ring has an extension extending towards the narrower end of the keystone.

3. A keystone as claimed in Claim 2 in which the internal diameter of the extention is greater than the internal diameter of the ring extending towards the wider end of the keystone so as to form a step in the bore of the keystone.

4. A keystone as claimed in any one of Claims 1 to 3 in which the inner surface of that portion of the inner annular ring extending towards the wider end of the keystone has a larger diameter towards the wider end of the keystone.

5. A keystone as claimed in any one of Claims 1 to 4 in which the inner annular ring is connected to the outer frusto-conical annular member by a plurality of integral radial ribs.

6. A keystone as claimed in any one of Claims 1 to 5 in which there is provided obturating means within the keystone.

7. A keystone as claimed in Claim 6 when appended to Claim 2 or 3 in which the obturating means comprises a disc abutting the step.

8. A keystone as claimed in any one of Claims 1 to 7 in combination with a member having a tapered body adapted to engage, in use the inner surface of the keystone.

9. A combination as claimed in Claim 8 in which the member has a filter adapted to filter beer passing through the member.

10. A combination as claimed in Claim 9 in which the member has an enlarged diameter portion adapted to receive a fitting to connect it, in use, to a suitable beer dispense system.

11. A combination as claimed in Claim 9 or 10 in which the filter comprises an apertured tube fitting over the end of the member.

12. A combination as claimed in any one of Claims 8 to 11 in which the member is formed of stainless steel or plastics material.

13. A keystone substantially as described with reference to Figures 1 to 3, or Figures 6 or 7 of the accompanying drawings.

14. A keystone and member combination as shown in Figures 4 and 5 in combination with Figures 1 to 3 and Figures 6 and 7 of the accompanying drawings.