Closure for a cylindrical opening having improved venting means

Claim 1

A closure for a cylindrical opening having improved venting means, comprising: a plug body having an inner end and an outer end, the plug body being of cylindrical external configuration for removeable positioning within a cylindrical opening, the plug body having means on the external cylindrical surface to seal against a cylindrical opening wall; means for retaining the plug body within a cylindrical opening against fluid pressure, the plug body having an axial opening therethrough, a portion of the opening communicating with the plug body outer end being of a larger internal diameter than the portion of the opening communicating with the plug body inner end forming an internal circumferential ledge; a tubular valve element slidably received in said plug body axial opening, the valve element having an enlarged external diameter portion adjacent the outer end and having at least one radial opening in the tubular wall adjacent to and spaced from the element inner end; a cap member closing said tubular valve element inner end; an annular groove within said plug body axial opening adjacent said plug body inner end; a gasket, such as an O-ring, in said groove slideably and sealably engaging said valve element external cylindrical surface; and a coiled spring receiving said valve element and compressibly positioned between said plug body opening circumferential ledge and said valve element enlarged external diameter portion which urges said valve element outer end towards said plug body outer end to cause said gasket to engage said valve element between said radial opening and said inner end to thereby close fluid flow through the valve element, the valve element being inwardly depressible by force applied against said outer end to expose said radial opening past said plug body inner end to allow the flow of fluid therethrough.