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