The valve assembly has a two part housing, one of {HEAD ~ the parts} having {TAIL ~ a sight glass} secured therein 
The valve assembly has a two part housing , one of { HEAD ~ the parts } having { TAIL ~ a sight glass } secured therein
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH