Patent ID: 6575326
Filing Date: 2003-06-10
Classification: B60P,B65D

Abstract:
A closure assembly for a containing structure, to hold liquid product, which containing structure defines a containing chamber for a liquid, and which has an opening, such as a manhole, defined by a ring structure, said assembly comprising:an outside cover member having an outer perimeter portion adapted to be positioned adjacent said ring structure, and also having a main inner portion extending across said perimeter portion, said inner portion having a venting structure leading to ambient atmosphere; a closure member adapted to be positioned in an operating location adjacent to said cover member, said closure member having an upper surface, a center location and a perimeter location where the upper surface has a positive slope from the center location to the perimeter location, the closure member further having an inner portion with an inner perimeter where vertical extensions are positioned and the inner portion is located below the venting structure; said closure member being characterized in that it has a relaxed position where in its operating location and without external forces applied thereto, the inner portion is spaced downwardly from said venting structure to permit air flow through said first vent opening, said closure member having an upwardly deflected position where, with an upper surge force exerted upon said closure member, the vertical extensions of the closure member are positioned against said cover member with the closure member coming in closing relationship with the venting structure but still allowing communication between the containing structure and the ambient air; said closure member being further characterized in that in its operating location the closure member provides a closure member vent opening spaced from said venting structure and leading to said containing chamber to permit air flow to and from said containing chamber to an area between said cover member and said closure member; whereby with the closure member in its operating location and in its relaxed position, said containing chamber can be vented to ambient atmosphere, and with a surge force exerted against said closure member, said closure member moves to its upwardly deflected partially closed position to allow moderate flow of liquid outwardly through said venting structure.