GB2170788A

GB2170788A - Tamper-proof seal

Info

Publication number: GB2170788A
Application number: GB08503098A
Authority: GB
Inventors: Patrick Lovell
Original assignee: KEGMASTER REDDITCH Ltd
Current assignee: KEGMASTER REDDITCH Ltd
Priority date: 1985-02-07
Filing date: 1985-02-07
Publication date: 1986-08-13
Also published as: GB8503098D0

Abstract

A tamper-proof seal for a container 15 having a closure comprises a cap 1 to fit over the closure and a locking ring 6 to snap over the cap, the locking ring having a surface which engages depending gripping fingers 2 on the cap and forces them inwardly to grip under a shoulder on the container. The cap 1 is held in place prior to locking by snap-action catches 5. The locking ring is provided with a rip tab. <IMAGE>

Description

SPECIFICATION Tamper-proof seal This invention concerns a tamper-proof seal for containers. It particularly but not exclusively reiates to tamper-proof seals of a plastics material for metal beer kegs.

Nowadays draught beer is frequently marketed in returnable metal kegs which have a screw-in valve which is fitted at the brewery. When it is desired to dispense the beer a special attachment is fitted to this valve, and there is no need to unscrew the valve from the keg. In fact it is not intended that the valve should ever be unscrewed, except at the brewery, and it is very dangerous to unscrew the valve of a keg which contains beer because the pressure within the keg can expel the valve with considerable force. To prevent unauthorised unscrewing of the valve, e.g. in an attempt to pilfer the contents of the keg, the valve is generally provided with a non-standard nut having an uneven number of sides, and which will therefore not fit a normal spanner, and the nut is generally protected by a plastics seal having a tear-off portion which cannot be removed without visibly damaging it.

This seal covers the nut and is intended to prevent a tamperer from gripping and unscrewing the nut with a tool. However, it has recently been discovered that kegs have been tampered with by first wrapping the keg valve including the seal with rags, and then unscrewing the valve through the rags and the tamper-proof seal using an adjustable wrench. The rags protect the seal from visible damage and the seal and the valve are removed as a unit, and can subsequently be replaced. There is therefore a need for an improved tamper-proof seal the usefulness of which cannot be nullified in this way.

According to one aspect of this invention, a tamper-proof seal for a container having a closure and a shoulder beneath the closure comprises a cap portion to fit over the closure and a locking ring portion to snap around and over the cap portion, wherein the cap portion has, around its circumference a plurality of depending deformable gripping fingers and the locking portion has, around its circumference, surface means to engage the gripping fingers and an associated shoulder, so that as the locking portion is pushed onto the cap portion which is already in position over the closure of a container, the said surface means forces the gripping fingers inwards so that they grip under the shoulder on the container whilst snapping into engagement with the shoulder on the locking portion, thus preventing removal of the seal without causing visible damage to it.

The locking ring portion preferably has one or more lines of weakening along which it can be easily broken either at the time of authorised removal, or during an attempt at pilfering or tampering with the contents of the container. The locking portion also preferably has a pull tab to assist such breakage. Although one line of weakening to enable breakage and opening of the locking ring would suffice, three such lines equally spaced around the periphery would be preferred.

The cap portion may also have peripheral means which enable it to be snap-fitted over the container closure without fitment of the locking ring. This enables the cap to be used alone simply as a dirt cover for the closure if a pilfer-proofing or tamperproofing facility is not required. In this case, the cap preferably has alternate gripping fingers and such snap-action catches around its periphery.

However, these snap action catches may be omitted.

Preferably, both the cap and the locking ring are of plastics material. Also preferably, the cap is of a softer and more readily deformable material than the locking ring. For example the cap could be of polyethylene and the locking ring of polypropylene.

As an added safeguard against undetected tampering, the cap and locking ring may be welded together at one point after fitment to the container, e.g. by sonic welding. The pull tab could thus be welded to the top of the cap, so that the weld would have to be broken to allow the pull tab to be lifted. The person authorised to open the container would know that the contents might have been interefered with if he found, as he opened it, that the pull tab and cap were not welded together.

Two tamper proof keg-seals according to the invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 is a cross-section of the cap filled over a container closure.

Figure 2 is a partial cross-section corresponding to Figure 1 and showing the locking ring fitted over the cap.

Figure 3 is a plan view of the cap of Figure 1.

Figure 4 is a plan view of the locking ring of Figure 2.

Figure 5, 6 and 7 show an alternative cap and locking ring, these views corresponding to Figure 1, 2 and 4 respectively.

The seal shown in Figures 1 to 4 comprises a cap having a top wall 1 and alternate depending gripping fingers 2 and snap-action catches 5. Each gripping finger comprises a generally downwardlyextending wall portion 14 having a camfered surface 4 at its lower end, and an inwardly extending locking portion 3. Each snap-action catch has an inwardly projecting chamfered bead to enable it to engage under a shoulder of a container neck 15 as shown in Figure 1. Although the cap can easily be removed it can be used on its own in this way simply to protect the closure from dirt. The locking ring 6 that provides the tamper-proof function when used in conjunction with the cap comprises a peripheral top wall 8 and a depending side wall 7.

The lower portion of the side wall has a sloping surface on its inside, tapering towards the bottom, and downwardly-sloping recessed shoulder 10 immediately above this tapering surface. A zone of weakening defined by two-closely-spaced parallel lines of reduced thickness 16 is provided in the top and side walls 7 and 8 and connected to a pull tab 12 so that pulling on the tab 12 will break the locking ring along either or both of the lines 11 to permit removal of the locking ring from the container.

The seal is fitted over the closure of a necked container 15 having a recessed shoulder beneath the closure, such as a keg closure which is flushed with the container neck, by firstly fitting the cap portion by means of the beads 13 on the snap-action catches 5 which engage beneath the shoulder on the container neck. The locking ring 6 is then pushed down over the cap so that the sloping surface 9 pushes the locking fingers 2 inwardly, whereby the locking portions 3 engage under the shoulder on the container. The sloping shoulder 10 on the cap eventually snaps into engagement with the chamfered surfaces 4 at the bottoms of the wall portions 14 of the locking fingers 2. The locking ring can now only be removed by breaking it, which will give a visual indication of tampering, and the cap cannot be removed from the container whilst the locking ring is in position.

The cap and locking ring shown in Figures 5, 6, and 7 are basically the same as those shown in Figures 1 to 4, but for possible added security the downwardly sloping shoulder 10 on the cap and the co-operating chamfered surface 4 on the locking ring have been replaced by surfaces 10a, 4a respectively which slope in the opposite directions.

The surface 10a has to be moulded using cores so that the top wall 8a of the locking ring necessarily has a ring of core holes 17.

In both embodiments, the pull tab 12 of the assembled seal may be spot-welded sonically to the top of the cap, for added security.

Claims

1. A tamper-proof seal for a container having a closure and a shoulder beneath the closure comprises a cap portion to fit over the closure and a locking ring portion to snap around and over the cap portion, wherein the cap portion has, around its circumference, a plurality of depending deformable gripping fingers and the locking portion has, around its circumference, surface means to engage the gripping fingers and an associated shoulder, so that as the locking portion is pushed onto the cap portion which is already in position over the closure of a container, the said surface means forces the gripping fingers inwards so that they grip under the shoulder on the container whilst snapping into engagement with the shoulder on the locking portion, thus preventing removal of the seal without causing visible damage to it.

2. A tamper-proof seal according to claim 1, wherein the locking ring portion has one or more lines of weakening along which it can be easily broken either at the time of authorised removal, or during an attempt at pilfering or tampering with the contents of the container.

3. A tamper-proof seal according to claim 2, wherein the locking portion has a pull tab to assist breakage thereof.

4. A tamper-proof seal according to claim 2, wherein the locking ring portion has three lines of weakening equally spaced around its periphery.

5. A tamper-proof seal according to any preceding claim, wherein the cap portion includes peripheral catch means which enable it to be snap-fitted over the container closure without fitment of the locking ring, to enable the cap to be used alone as a dirt cover for the closure.

6. A tamper-proof seal according to claim 5, wherein the cap has alternate gripping fingers and catch means around its periphery.

7. A tamper-proof seal according to any preceding claim, wherein both the cap and the locking ring are of plastics materials, the cap being of a softer and more readily deformable material than the locking ring.

8. A tamper-proof seal according to claim 7, wherein the cap is of polyethylene and the locking ring of polypropylene.

9. A tamper-proof seal according to any preceding claim, wherein the cap and locking ring are welded together at one point after fitment to the container.

10. A tamper-proof seal according to claim 9, wherein the pull tab is welded to the top of the cap, so that the weld must be broken before the pull tab can be lifted.