GB2531979A

GB2531979A - Inspection chamber cover marking device

Info

Publication number: GB2531979A
Application number: GB1602304.6A
Authority: GB
Inventors: Denton Roy
Original assignee: Individual
Current assignee: Individual
Priority date: 2016-02-09
Filing date: 2016-02-09
Publication date: 2016-05-04
Anticipated expiration: 2036-02-09
Also published as: GB2531979B; GB201602304D0

Abstract

The invention relates to a marking device 20 to be mounted on an inspection chamber cover 10. The device is releasably secured to the inspection chamber cover 10 using its keyhole. It comprises a retainer 42 whose shape and size is such that the retainer is insertable through a keyhole. After insertion, rotating the retainer through enables it to engage with an under-surface of the inspection chamber cover. A mechanical fastener arrangement 32 (which may be a screw) couples the marker to the retainer and is operable to draw the marker toward the retainer. To mount the marking device upon the inspection chamber cover the retainer is inserted through the keyhole and rotated through a part turn, after which the mechanical fastener is operated to draw the retainer toward the marker, so that the retainer engages the under-surface of the inspection cover and so secures the marking device in position with the marker visible at an exterior surface of the inspection chamber cover. The marker is preferably formed as a plate carrying visual information such as a hazard warning.

Description

INSPECTION CHAMBER COVER MARKING DEVICE

The present invention is concerned with safety in relation to underground inspection chambers.

The term "inspection chamber" is used herein to refer to any underground chamber to which human access is at least occasionally required and which has an entrance covered by an inspection chamber cover in the form of a movable plate. Colloquially, the term "manhole" is often used to refer to certain inspection chambers and their covers are referred to as "manhole covers". Inspection chambers are often part of underground utility systems such as sewers, storm drains, telephone or electricity networks and supply networks for water or gas.

A traditional inspection chamber cover is a metal item, often of cast iron, received in a substantial metal base mounted horizontally in the ground and forming a frame around the opening to the inspection chamber. The cover rests on a small inset rim of the base so that its top surface may be flush with the surrounding ground surface, such as a road or pavement.

It serves to prevent pedestrians from falling into the inspection chamber, to exclude foreign bodies, and to provide continuity in a road or pavement surface. The inspection chamber cover may be hinged to the base or it may be removable. It may be maintained in position on the base by its weight alone or by some form of locking mechanism. Not all inspection covers are metal. Concrete is also used for this purpose, as are plastics including composite plastics based materials such as glass reinforced plastic.

Provision needs to be made for the inspection chamber cover to be lifted out of the base for access to the inspection chamber. To this end, the cover is often provided with a keyhole in its upper surface to receive a lifting key. The shape of the lifting key and the keyhole are such that the key is freely insertable into the hole, after which a part-turn of the key causes it to engage with the cover and enable it to be lifted. A whole range of different mechanical devices is available for raising the key to lift the cover, from simple levers and spreader bars to hydraulic jacks, removable gantries and so on.

There are a number of hazards that may be encountered in an inspection chamber. These include the presence of dangerous gases, chemical spills, high rates of water flow and structural defects in the chamber itself, e.g. unsafe brickwork or broken ladders. Where inspection reveals such hazards it is important to alert subsequent visitors to the chamber to them. The challenge in this respect is to some extent to do with communication of information. Hazards are often identified, either because they arise from an emergency such as a chemical spill or in the course of routine maintenance or inspection visits, but reports of such hazards are often ignored or not brought to the attention of subsequent visitors.

According to the present invention there is an inspection chamber marker according to claim 1. The invention makes it possible for a safety marking to be applied to an inspection cover to alert users to hazards and it does so in a way that is quick and convenient to implement, robust and durable, and difficult for those accessing the inspection chamber to ignore.

Specific embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings, in which:-Figure 1 is a simplified plan view of an inspection chamber cover which belongs to the prior art; Figure 2 is an exploded view from one side of a marking device embodying the present invention; Figure 3A is a plan view of the marking device and Figure 3B is a section in a vertical plane through a marker plate 22 of the marking device; Figures 4A and 4B are plan and side views respectively of a retainer used in the marking device; and Figure 5 is a section in a vertical plane through the inspection chamber cover with the marking device mounted upon it.

The present invention makes it possible for a safety marking to be applied to an inspection cover in a way that is quick and convenient to implement, robust and durable, and difficult for those accessing the inspection chamber to ignore.

Figure 1 shows the salient features of an inspection chamber cover 10. This example comprises a circular plate 12 although covers with other shapes are commonplace. A keyhole 14 is provided to enable the inspection chamber cover 10 to be lifted. The drawing shows one widely used shape for the keyhole, which has a circular central portion 16 and a pair of lobes 18 on opposite sides of it. This form of keyhole may for example be used in conjunction with a "T" shaped lifting key (not illustrated). The key's crosspiece is aligned with the lobes 18 to enable the key to be inserted into the keyhole. Subsequently turning the key through a part turn (e.g through an angle of about 90 degrees) causes the crosspiece to engage with an under-surface of the inspection chamber cover 10 to carry its weight.

The illustrated shape of the keyhole 14 serves as an example only. The feature in question is referred to as a "keyhole" simply because it is able to engage with a lifting key. Numerous variants of the keyhole's shape are known. For example the keyhole may be rectangular. It may form a through-going opening in the inspection chamber cover 10 but that is not essential -it may instead be formed as a recess, shaped to provide an under-surface for engagement with the key.

The present invention provides an inspection chamber marker which engages with the keyhole 14 of the inspection chamber cover. This is advantageous for several reasons:- -inspection chamber covers come in a wide range of different shapes, sizes and designs but most incorporate a keyhole for lifting, so the device described herein can be used with most existing covers without any need for them to be modified; -the keyhole structure is necessarily robust because it needs to support the weight of the inspection chamber cover during lifting. Hence it is able to provide a robust mounting for the marking device, which is important given that the inspection chamber cover may be subject to road and/or foot traffic; -the marking device must be removed before the keyhole 14 can be used to lift the inspection chamber cover, making it impossible for a person lifting the cover to overlook it; -a device that mechanically engages with the keyhole 14 can be easily installed and easily removed.

The marking device 20 depicted in Figures 2 to 4 comprises a marker plate 22 which lies upon the upper surface of the inspection chamber cover 10 when the marking device is in situ (see Figure 5) so that its upper face 24 is clearly visible to anyone looking down at the cover. Safety markings 26 provided on the upper face serve to alert users to the existence of a hazard in the inspection chamber and may provide additional information. For example the markings 26 may specify the nature of the hazard. A system of colour coding may be used, in which for example yellow markings indicate possible presence of gas, blue markings warn of high water flow and red markings indicate structural defects in the chamber. Additionally or alternatively the marker plate may carry text or icons to convey warning information, or indeed information of some other type. It may carry a serial number or machine readable code referenced to an entry in a database relating to the inspection chamber.

The marker plate 22 is in the present embodiment shallow in depth, being formed as a metal plate thin enough to pose little hazard of tripping pedestrians or of damage to passing vehicle tyres. In the illustrated example the marker plate is triangular in plan but other shapes could be used -it could for example be square, circular or rectangular. In the present embodiment the marker plate 22 is provided with a locating feature receivable by the keyhole 14. This takes the form of an integrally formed boss 28 protruding from the plate's lower face 30. The boss may be sized for receipt in the circular central portion 16 of the keyhole 14, and be too large to pass into its lobes 18, thereby positively locating the marking device 20 and preventing it from sliding about.

The lower face 30 of the marker plate 22 may be provided with a high friction surface to resist sliding or turning of the marking device 20. This may for example comprise an elastomer or polymer coating. The upper face 24 of the marker plate 22 may be provided with a non-slip surface so that the device offers no hazard with respect to slipping or skidding. For example it may be coated with set plastics resin incorporating grit or other non-slip features.

The device 20 comprises a mechanical fastener 32 which passes through and engages with the marker plate 22 to releasably secure it in position upon the inspection chamber cover 10.

The upper face 24 of the marker plate 22 provides a recess 34 to receive an engagement head 36 of the mechanical fastener 32. Due to the provision of the recess 34, the engagement head 36 lies beneath the plane of the outer face 24 of the marker plate 22 avoiding any tripping hazard. In the present embodiment the mechanical fastener 32 comprises a machine screw and its engagement head 36 is of countersunk (frusto-conical) form. It is provided with a driving feature 38 (see Figure 3A) to enable the mechanical fastener to be driven (turned) with a suitable tool. In the illustrated example this feature is a hexagonal recess for receiving a conventional Allen key but it could take other forms. The recess 34 is formed by a curved transition between the flat marker plate 22 and its boss 28. The boss 28 defines a through-going opening 40 in the marker plate 22 through which the mechanical fastener 32 is passed.

In the present embodiment the marker plate 22 and its boss 28 are formed by pressing a metal sheet. Other materials and other manufacturing techniques may however be employe Beneath the marker plate 22, the mechanical fastener 32 carries a retainer 42 which is shaped to function in the manner of a part turn lock, being insertable through the keyhole 14 in the inspection chamber cover 10 when suitably aligned, but subsequently rotatable through a part turn to engage with an under-surface of the inspection cover 10. In the illustrated example the retainer 42 comprises a hexagonal body portion 44, formed in the manner of a nut with a threaded bore 45. Projecting from opposite sides of the body portion 44 are engagement lobes 46. The plan shape of the retainer 42 (seen in Figure 4a) is thus complementary to the shape of the keyhole 14. When the retainer's lobes 46 are aligned with the lobes 18 of the keyhole 14, the retainer is able to be inserted into the keyhole 14. Turning the retainer 42 through an angle -say 90 degrees -brings the engagement lobes 46 into position to engage the underside 48 of the inspection chamber cover 10 (see Figure 5) and so prevents withdrawal of the retainer. The retainer 42 may take a variety of forms commensurate with its function. It could for example be shaped as a simple bar with a transverse, through-going threaded bore.

A spring 50 is provided, being pre-stressed between a ledge or shoulder 52 at the lower end of the boss 28 (see Figure 3B) and the engagement head 36 of the mechanical fastener 32. Hence the spring urges the fastener 32 and the retainer 42 upwards, relative to the marker plate 22.

To install the marking device 20, the retainer 42 is aligned with the keyhole 14 and inserted into it. By means of the mechanical fastener 32, the retainer 42 is then turned through an angle of roughly 90 degrees. This involves depressing the mechanical fastener 32 against the force of the spring 50. When the spring is then released, it raises the fastener 32 and the retainer 42, bringing the retainer 42 into engagement with the underside 48 of the inspection chamber cover 10. Frictional engagement of the retainer 42 with the underside 48 is sufficient to keep the retainer 42 stationary while the mechanical fastener 32 is then turned using a suitable tool engaged with the driving feature 38, causing the mechanical fastener 32 to draw the retainer 42 firmly toward the marker plate 22. In this way the retainer 42 is drawn firmly against the underside 48 of the inspection chamber cover to retain the device securely in position.

The portions 46 of the retainer 42 which engage the cover 10 are in the present embodiment provided with a high friction surface to resist any tendency for the retainer 42 to spin as the mechanical fastener 32 is tightened. This surface may for example comprise an elastomer or polymer coating.

To subsequently remove the marking device 20, the mechanical fastener 32 is turned in the opposite direction by means of its driving feature 38. This will typically loosen the retainer 42, allowing it to turn until it is aligned suitably to be released from the keyhole 14. If the retainer has -e.g. due to corrosion -become unable to turn with respect to the mechanical fastener 32 no problem arises, since in this case the retainer 42 will nonetheless turn along with the mechanical fastener 32 until it is released from the keyhole 14.

The aforegoing embodiments are presented by way of example and not limitation. Numerous possible variants and modifications will be apparent to the skilled person, within the scope of the invention as defined by the appended claims.

Claims

CLAIMS1. An inspection chamber cover marking device comprising a marker having an upper face for carrying visual information; a retainer whose shape is such that the retainer is insertable through a keyhole in an inspection chamber cover when suitably aligned, but is subsequently rotatable through a part turn to enable the retainer to engage with an under-surface of the inspection chamber cover and so resist withdrawal of the retainer; a mechanical fastener arrangement which couples the marker to the retainer and is operable to draw the marker toward the retainer, so that to mount the marking device upon the inspection chamber cover the retainer is inserted through the keyhole and rotated through a part turn, after which the mechanical fastener is operated to draw the retainer toward the marker, so that the retainer engages the under-surface of the inspection cover and so secures the marking device in position with the marker visible at an exterior surface of the inspection chamber cover.
2. A marking device as claimed in claim 1 in which the marker comprises a plate.
3. A marking device as claimed in claim 2 in which the marker plate has a depending boss insertable in the keyhole of the inspection chamber cover.
4. A marking device as claimed in any preceding claim in which the mechanical fastener comprises a threaded member.
5. A marking device as claimed in claim 4 in which the threaded member is received in a threaded bore of the retainer.
6. A marking device as claimed in claim 5 in which the threaded member is provided with an enlarged head receivable in a recess of the upper face of the marker so that the enlarged head lies beneath the said upper face.
7. A marking device as claimed in any of claims 4 to 6 in which the retainer is provided with a high friction surface contactable with the under-surface of the inspection cover, thereby to resist turning of the retainer as the threaded member is turned.
8. A marking device as claimed in any of claims 4 to 7 further comprising a pre-stressed spring arranged to bias the retainer upwardly into engagement with the under-surface of the inspection chamber cover.
9. An inspection chamber cover which comprises a keyhole and upon which is mounted a marking device as claimed in any preceding claim.
10. A method of providing a safety warning relating to an inspection chamber, comprising securing a marking device to a keyhole of a cover of the inspection chamber.
11. A method as claimed in claim 10, wherein the marking device is as claimed in any of claims 1 to 8.
12. An inspection chamber cover marking device substantially as herein described with reference to, and as illustrated in, the accompanying drawings.