GB1578747A

GB1578747A - Security sealing devices

Info

Publication number: GB1578747A
Application number: GB26574/76A
Authority: GB
Original assignee: Sangamo Weston Ltd; Sangamo Weston Inc
Current assignee: Sangamo Weston Ltd; Atos Origin IT Services Inc
Priority date: 1976-06-25
Filing date: 1976-06-25
Publication date: 1980-11-12
Also published as: ZA773684B; DE2727949A1; FR2356221A1; AU2631777A

Description

(54) IMPROVEMENTS IN OR RELATING TO SECURITY SEALING DEVICES (71) We, SANGAMO WESTON LIMITED, a British company, of Great Cambridge Road, Enfield, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed ,to be particularly described in and by the following statement: This invention relates to security sealing devices, and is particularly concerned with methods of protecting meters, such as electricity supply meters, from being opened for the purpose of tampering with the meter mechanism or fraudulently abstrcting the electricity (or other utlity) being supplied.

The majority of instruments, meters and apparatus which incorporates a recording, measuring or indicating mechanism within a chamber to which access cannot normally be gained have a housing formed in at least two parts, such as a cover and a base, which must be maintained in a secure relationship. In the case of electricity supply meters for example the housing comprises a base which is secured to a meter board, a cover which is fitted to the base, and a terminal door through which the supply leads pass to the internal metering mechanism.

The traditional method of protecting electricity supply meters against illegal entry to the meter mechanism consists of the use of wire and lead seals on the meter cover fixing screws and on the terminal door fixing screws. Such seals consist of a wire which is passed through a cross-drilled hole in the head of each fixing screw and through part of the meter casing, so that any attempt to turn the screw results in a broken sealing wire. The seal on the cover or terminal door having been broken there is then no further bar to the removal or partial removal of the meter cover or the terminal door, and the only evidence that the meter has been tampered with is the broken sealing wire or seal. Such wire and lead seals are comparatively frail and it is difficult to refute the argument by the customer that the seal has been broken accidentally.

It is an object of the present invention to provide improved security sealing means, particularly for protection of such meters, by introducing a second barrier beyond the wire and lead seal to prevent access to the interior of the meter.

Our U.K. Patent Specification No.

1 429 235 gives details of security sealing devices which constitute a second barrier of this nature, and which are based upon a design which involves the provision of a zone of weakness at which a securing element is designed to fracture if the security device is tampered with. The security sealing devices described in the aforesaid patent specification are not applicable however to all types of meter housing, and the security sealing device in accordance with the present invention provides an alternative device which is more generally applicable to a wide range of meter housings.

In accordance with the present invention there is provided a security sealing device comprising a rigid elongate element having a screw-threaded portion at one end thereof and at the other end thereof axially spaced inner and outer enlarged heads with a zone of weakness therebetween at which the outer head is arranged to shear off from the inner head when subjected to a predetermined torque, and a guard element engageable with the inner head of the elongate element, the guard element having a recess to accommodate said inner head and a wall portion arranged to underlie said inner head and apertured to enable the elongate element to extend therethrough.

Preferably, the guard element is cupshaped with said wall portion forming the base of the cup and with an upstanding wall portion around the inner head in close spaced relationship thereto.

According to another preferred feature of the invention the guard element is provided with a flat surface arranged in use to contact an adjacent rigid surface to prevent rotation of the guard element about the axis of the elongate element. The guard element may also be drilled with holes through which a sealing wire can be passed, thereby to permit the use of a conventional wire and lead seal as an additional security means.

Furthermore, an axial hole may be provided centrally through the outer head and into the inner head of the elongate element to provide a centering hole in the inner head when the outer head is sheared off.

This centering hole can assist in the removal of the elongate element, for example if it needs to be removed for the purpose of servicing a meter enclosed within a housing secured by the security sealing devices.

In order that the invention may be fully understood embodiments of security sealing device in accordance therewith will now be described by way of example and with reference to the accompanying drawing, in which: Fig. 1 is a part sectional view through a first embodiment of security sealing device in accordance with the invention; Fig. 2 is a plan view of the security sealing device of Fig. 1; Fig. 3 is a part sectional view similar to Fig. 1 but showing the device as finally installed; Fig. 4 illustrates an alternative form of guard element; Fig. 5 illustrates schematically how the security sealing device may be removed; and, Fig. 6 shows a modified form of shearhead screw.

Although the invention has wide application as a security sealing device, the invention will hereinafter be described with particular reference to electricity supply meters.

The present invention particularly concerns means for protecting both the meter cover and also the terminal door of electricity supply meters, but clearly can be extended to use with other meters or indeed any- recording or measuring or indicating apparatus where it is important to prevent unauthorised access to the interior of a chamber.

The security sealing device shown in Figs.

1 to 3 is designed to secure together two housing parts of an electricite supply meter, for example a meter base 10 and a meter cover 12. The meter cover 12 is provided with a substantially semi-cylindrical boss 14 which has a cylindrical bore 16 formed therethrough. A plurality of bosses 14 would normally be provided around the perimeter of the meter cover for securement to the base 10. The meter base 10 receives an insert or nut 18 which has an internal screwthreaded bore. A rigid elongate element 20 in the form of a shear-head screw has its screw-threaded portion 22 received within the bore in the nut 18. The screw 20 has a true head 24 of larger diameter than the stem of the screw, and also a driving head 26 with a reduced diameter portion 28 therebetween constituting a zone of weakness. The driving head 26 is slotted to enable the screw to be turned by a screwdriver or other tool.

A substantially cylindrical cup-shaped guard element 30 is provided around the head of the screw 20. The guard element 30 has a base portion 32 sandwiched between the true head 24 of the screw and the adjacent surface of the meter cover boss 14. The base portion 32 is apertured for the stem of the screw 20 to pass therethrough. The guard element 30 has an upstanding wall portion 34 which is crossdrilled as indicated at 36. The guard element 30 also has a flat surface 38 which in use abuts a corresponding flat surface 40 on the meter cover, thereby to prevent rotation of the guard element and prevent any risk of loosening the screw by rotating the cup. The flat surface 38 is positioned in relation to the cross-drilled holes 36 such that the holes are aligned in the optimum position for convenient fitting of a sealing wire 42.

In fitting the security sealing device, the screw 20 is overtightened, thus shearing off the driving head 26 and, as shown in Fig.

3, leaving no means in the true head 24 of unscrewing the screw. The cup-shaped guard element 30 denies access to the outside diameter of the true head 24 so that the screw cannot be removed by gripping the true head. A cap 44 provided with cross-drilled holes 46 is then fitted into the cup-shaped guard element 30 as shown in Fig. 3, and the sealing wire 42 is passed through the cross-drilled holes 36 and 46 in the cup and cap, thus completely enclosing the screw head until the sealing wire 42 is removed. A lead seal 48 connects the ends of the sealing wire 42. The cup-shaped guard element 30 and the cap 44 may be turned in metal or plastics material, or may be moulded from plastics material.

Alternatively, the cup and cap 30 and 44 may be formed from sheet material. This is simplified if the cup and cap are of rectilinear rather than cylindrical shape, for example as shown in Fig. 4. As shown in Fig.

4 the guard element 305 has straight upstanding walls 34a and a square cap 44a is arranged to be fitted within the cup. The provision of an upstanding side wall 34s on the side of the cup adjacent to the flat sur face 40a of the meter cover may be dispensed with as the end faces of the crossdrilled side walls 34a will abut against this flat surface 40n to form a complete enclosure.

At infrequent intervals it may be necessary to remove the meter cover 12 for the purpose of servicing the meter mechanism within the chamber. The screws 20 may be removed by drilling through the head of the screw. One of two alternative methods may be adopted. As shown in Fig. 5, the cap 44 is removed and a hardened steel bush 50 is dropped temporarily into the cup 30 to act as a jig to centre a drill 52.

The drill is of a diameter slightly larger than that of the stem of the screw 20 so that when the drill passes through the head 24 of the screw the guard element can be removed and the meter cover lifted off, leaving an ample length of screw stem extending from the base for the screw to be removed easily. All the parts except the screw 20 may be salvaged for use again after servicing of the equipment.

Alternatively, as shown in Fig. 6, a hole 54 may be provided axially in the centre of the screw passing through the driving head 26 and down into the true head 24 of the screw. Thus, after the driving head 26 has been sheared off, there will be sufficient depth of hole 54 remaining in the true head 24 for this hole to act as a centering point for the drill.

WHAT WE CLAIM IS: 1. A security sealing device comprising a rigid elongate element having a screwthreaded portion at one end thereof and at the other end thereof axially spaced inner and outer enlarged heads with a zone of weakness therebetween at which the outer head is arranged to shear off from the inner head when subject to a predetermined torque, and a guard element engageable with the inner head of the elongate element, the guard element having a recess to accommodate said inner head and a wall portion arranged to underlie said inner head and apertured to enable the elongate element to extend therethrough.

2. A security sealing device as claimed in claim 1, in which the guard element is cup-shaped with said wail portion forming the base of the cup and with an upstanding wall portion around said inner head in close spaced relationship thereto.

3. A security device as claimed in claim 2, in which the apertured wall portion is rectangular with the upstanding wall portion provided on at least three sides of the apertured wall portion.

4. A security sealing device as claimed in any preceding claim, in which the guard element is provided with a flat surface arranged in use to contact an adjacent rigid surface to prevent rotation of the guard element about the axis of the elongate element.

5. A security dealing device as claimed in any preceding claim, in which the guard element is provided with apertures through which an elongate sealing means can be passed to overlie the inner head of the elongate element seated in said recess.

6. A security sealing device as claimed in any preceding claim, which includes a cap shaped to fit within said recess in the guard element and to overlie said inner head.

7. A security sealing device as claimed in claim 6 when dependent upon claim 5, in which the cap is also provided with apertures in alignment with the guard element apertures and through which said elongate sealing means can be passed.

8. A security sealing device as claimed in any preceding claim, in which an axial hole is provided centrally through the outer head and into the inner head to provide a centering hole in the inner head when the outer head is sheared off.

9. Apparatus comprising a first housing part, a second housing part, and one or more security sealing devices as claimed in any of claims 1 to 8 holding said two housing parts together, one of said housing parts being provided with a screw-threaded bore to receive the screw-threaded portion of said elongate element, and the other of said housing parts having a bore therethrough for said elongate element and being held between said one housing part and the apertured wall portion of the guard element.

10. Apparatus as claimed in claim 9, in which said other housing part includes a flat surface adjacent to the guard element and against which a surface of the guard

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. face 40a of the meter cover may be dispensed with as the end faces of the crossdrilled side walls 34a will abut against this flat surface 40n to form a complete enclosure. At infrequent intervals it may be necessary to remove the meter cover 12 for the purpose of servicing the meter mechanism within the chamber. The screws 20 may be removed by drilling through the head of the screw. One of two alternative methods may be adopted. As shown in Fig. 5, the cap 44 is removed and a hardened steel bush 50 is dropped temporarily into the cup 30 to act as a jig to centre a drill 52. The drill is of a diameter slightly larger than that of the stem of the screw 20 so that when the drill passes through the head 24 of the screw the guard element can be removed and the meter cover lifted off, leaving an ample length of screw stem extending from the base for the screw to be removed easily. All the parts except the screw 20 may be salvaged for use again after servicing of the equipment. Alternatively, as shown in Fig. 6, a hole 54 may be provided axially in the centre of the screw passing through the driving head 26 and down into the true head 24 of the screw. Thus, after the driving head 26 has been sheared off, there will be sufficient depth of hole 54 remaining in the true head 24 for this hole to act as a centering point for the drill. WHAT WE CLAIM IS:

1. A security sealing device comprising a rigid elongate element having a screwthreaded portion at one end thereof and at the other end thereof axially spaced inner and outer enlarged heads with a zone of weakness therebetween at which the outer head is arranged to shear off from the inner head when subject to a predetermined torque, and a guard element engageable with the inner head of the elongate element, the guard element having a recess to accommodate said inner head and a wall portion arranged to underlie said inner head and apertured to enable the elongate element to extend therethrough.

element engages to prevent rotation of the guard element about the axis of the elongate element.

11. A security sealing device substantially as hereinbefore described with reference to the accompanying drawings.

12. An electricity supply meter fitted with one or more security sealing devices as claimed in any of claims 1 to 8 or 11.