the valve seat further comprising a generally flat diaphragm engaging surface having a second surface area, {HEAD ~ the second surface area} being less than {TAIL ~ the first surface area} 
less than
the valve seat further comprising a generally flat diaphragm engaging surface having a second surface area , { HEAD ~ the second surface area } being less than { TAIL ~ the first surface area }
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 OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL