Patent EP0031641A2 successfully refreshed from Google Patents.
EP0031641A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Removable covers and frames therefor
Assignee: Dover Engineering Works Ltd
•
Filing: 1980-11-12
•
Granted: —
•
Expires: 2000-11-12
Abstract
Abstract A manhole cover unit 1 comprises a cover 2 which is seated in a frame 3 to cover over a pit opening 7 the mouth of which is bounded by the frame. To protect the cover 2 against the effect of effluent gases escaping from the pit opening 7 when the unit 1 is used in a sewerage system, a barrier plate 4 is seated on a base flange 10 of the frame 3 so as to extend across the mouth of the pit opening below the cover. The barrier plate 4 is of a material which is resistant to corrosion such as a glass fibre reinforced synthetic plastics. To ensure that effluent gases do not escape past the barrier plate 4, a gasket 5 is bonded around its margin to seal against the base flange 10 on a ledge 12 thereof formed by a rebate 11. The gasket 5 is urged into sealing engagement with the ledge 12 by the weight of the cover 2 when resting on the base flange 10. The cover may have a solid top braced by a honeycomb ribbed structure on its underside. The cover 2 and frame 3 may be of cast iron.
Inventors
- 👤 Clive Bowley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 15:59
CPC Classifications
E; E02; E02D; E02D29/00; E02D29/12; E02D29/14; E02D29/149; E02D29/1454; E02D29/1463
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
81 words
A cover unit for a pit opening, comprising a frame for bounding the mouth of the opening, a cover seated in the frame to close off the opening, and a gas impervious barrier plate which is supported by the frame to extend across the opening beneath the cover and which is urged by the weight of the cover into making a gas-tight seal with the cover to inhibit the passage to the cover of any gaseous material passing up the opening.
Claim 2
Dependent Claim
81 words
A cover unit for a pit opening, comprising a frame for bounding the mouth of the opening, a cover seated in the frame to close off the opening, and a gas impervious barrier plate which is supported by the frame to extend across the opening beneath the cover and which is urged by the weight of the cover into making a gas-tight seal with the cover to inhibit the passage to the cover of any gaseous material passing up the opening.
Claim 3
Dependent Claim
21 words
A cover unit as claimed in claim 1, wherein the material of the barrier plate is a glass reinforced synthetic plastics.
Claim 4
Dependent Claim
28 words
A cover unit as claimed in claim 1 or claim 2, wherein the gas-tight seal is made by a sealing gasket between the barrier plate and the frame.
Claim 5
Dependent Claim
22 words
A cover unit as claimed in claim 3, wherein the sealing gasket is carried by the barrier plate on the underside thereof.
Claim 6
Dependent Claim
15 words
A cover unit as claimed in claim 4, wherein the sealing gasket is of neoprene.
Claim 7
Dependent Claim
21 words
A cover unit as claimed in claim 4 or claim 5, wherein the sealing gasket is bonded to the barrier plate.
Claim 8
Dependent Claim
62 words
A cover unit as claimed in any of the preceding claims, wherein the frame includes an internal flange on which the cover is supported when seated in the frame, the internal flange being rebated along its inner periphery to provide a ledge around the pit opening, and the barrier plate resting on the ledge below the cover to extend across the opening.
Claim 9
Dependent Claim
24 words
A cover unit as claimed in claim 7, wherein the frame has a generally L cross-section the base of which constitutes the internal flange.
Claim 10
Dependent Claim
31 words
A cover unit as claimed in claim 8, wherein the frame comprises four perimeter bars joined together at the corners of the frame, each perimeter bar having the generally L cross-section.
Claim 11
Dependent Claim
27 words
A cover unit as claimed in claim 9, wherein the perimeter bars are joined together by being bolted together and the joints between the bars are sealed.
Claim 12
Dependent Claim
101 words
A cover unit as claimed in claim 9 or claim 10, wherein the perimeter bars comprise a front end bar, a back end bar, a left hand side bar and a right hand side bar, the uprights of the L cross-section of the two side bars being inclined to the vertical in opposite directions so that the spacing between the opposite uprights is greater at the top then at their junctions with the respective base flanges, and the uprights of the L cross-section of the two end bars being inclined in the same direction and towards the front of the frame.
Claim 13
Dependent Claim
79 words
A cover unit as claimed in any of claims 9 to 11, wherein the perimeter bars define a well whose base is constituted by the base flange of each L cross-section bar and whose perimeter is defined by the uprights of the L cross-section bars, the cover being sunk in the well so that not only is it supported on the base flanges but its perimeter generally conforms to and snugly fits against the internal perimeter of the well.
Claim 14
Dependent Claim
25 words
A cover unit as claimed in claim 12, wherein those surfaces of the cover and the frame which contact one another have a machined finish.
Claim 15
Dependent Claim
39 words
A cover unit as claimed in claim 13, wherein the surfaces of one of the cover and the frame have a milled finish and the surfaces of the other of the cover and the frame have a ground finish.
Claim 16
Dependent Claim
56 words
A cover unit as claimed in any of claims 11 to 14, wherein each L cross-section perimeter bar is strengthened by an external rib integral with the upright thereof and extending lengthwise of the upright, and by external flanges also integral with the upright and projecting laterally outwardly thereof and fashioned integral with the lengthwise rib.
Claim 17
Dependent Claim
38 words
A cover unit as claimed in claim 15, wherein each perimeter side bar terminates at its ends in further external flanges at which to be bolted to the uprights at the adjacent ends of the two end bars.
Claim 18
Dependent Claim
24 words
A cover unit as claimed in any of the preceding claims, wherein the barrier plate has carrier strap means attached to its top surface.
Claim 19
Dependent Claim
80 words
A cover unit as claimed in any of the preceding claims, wherein the cover comprises a solid top plate reinforced by a depending honeycomb rib structure, the base of which is supported in the frame and through which the weight of the cover is transmitted to the barrier plate to press the barrier plate against the frame, and the perimeter of the honeycomb rib structure and the solid top plate makes seating contact with the internal perimeter of the frame.
Claim 20
Dependent Claim
21 words
A cover unit as claimed in any of the preceding claims, wherein the cover and the frame are of cast iron.
Claim 21
Dependent Claim
157 words
A cover unit for a pit opening, comprising a cast iron frame defining a well having an open base and a perimeter around the base, a cast iron cover mounted in the frame well to be supported on the base and close off the opening therein and fit against the perimeter of the frame, the mating surfaces of the cover and the frame having a machined finish so that there is metal-to-metal contact therebetween, and a barrier plate which is impervious to gas and which is not subject to corrosion by effluent gases from sewerage supported by the base of the frame below the cover and spanning the opening in the open base, the weight of the cover pressing the plate downwardly upon the frame base by which the plate will provide a gas impervious barrier between the underside of the cover and effluent gases from sewerage when the cover unit is used in a sewerage system.
Claim 22
Dependent Claim
157 words
A cover unit for a pit opening, comprising a cast iron frame defining a well having an open base and a perimeter around the base, a cast iron cover mounted in the frame well to be supported on the base and close off the opening therein and fit against the perimeter of the frame, the mating surfaces of the cover and the frame having a machined finish so that there is metal-to-metal contact therebetween, and a barrier plate which is impervious to gas and which is not subject to corrosion by effluent gases from sewerage supported by the base of the frame below the cover and spanning the opening in the open base, the weight of the cover pressing the plate downwardly upon the frame base by which the plate will provide a gas impervious barrier between the underside of the cover and effluent gases from sewerage when the cover unit is used in a sewerage system.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.