{HEAD ~ An annular protrusion} axially extends from the valve body and is symmetrical about {TAIL ~ the orifice} 
is symmetrical about
{ HEAD ~ An annular protrusion } axially extends from the valve body and is symmetrical about { TAIL ~ the orifice }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL