bias means comprising at least one flexible strand maintained under tension connected between said valve member and said valve seating portion on the other side of said opening for maintaining {HEAD ~ a substantial seating force} on {TAIL ~ said valve member} when said valve opening has closed, and 
on
bias means comprising at least one flexible strand maintained under tension connected between said valve member and said valve seating portion on the other side of said opening for maintaining { HEAD ~ a substantial seating force } on { TAIL ~ said valve member } when said valve opening has closed , and
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 TAIL OTH OTH OTH OTH OTH OTH OTH OTH