An annular recess is formed in {HEAD ~ an outer surface} of {TAIL ~ the orifice ring} and has first and second axially spaced walls 
of
An annular recess is formed in { HEAD ~ an outer surface } of { TAIL ~ the orifice ring } and has first and second axially spaced walls
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH