In {HEAD ~ this embodiment}, {TAIL ~ the generally flat truncated surface} of the dome shaped valve seat is the diaphragm engaging surface 
In { HEAD ~ this embodiment } , { TAIL ~ the generally flat truncated surface } of the dome shaped valve seat is the diaphragm engaging surface
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH