As shown in FIG 1, {TAIL ~ the valve member} 20 preferably has a generally T shaped cross section with the top portion 21 of {HEAD ~ the T} being disposed adjacent the opening 26 and the bottom 23 of the T being disposed within the opening 28 
As shown in FIG 1 , { TAIL ~ the valve member } 20 preferably has a generally T shaped cross section with the top portion 21 of { HEAD ~ the T } being disposed adjacent the opening 26 and the bottom 23 of the T being disposed within the opening 28
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 HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH