wherein the annular surface has a radially inner portion and a radially outer portion, and said continuous seal is located at least on said radially outer portion, while {HEAD ~ the radially inner portion} allows {TAIL ~ the seal} of the valve to be brought into sealing engagement with the tubular body 
allows
wherein the annular surface has a radially inner portion and a radially outer portion , and said continuous seal is located at least on said radially outer portion , while { HEAD ~ the radially inner portion } allows { TAIL ~ the seal } of the valve to be brought into sealing engagement with the tubular body
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH