An additional tubular insert member is held within {HEAD ~ the principal conduit member} to open and close {TAIL ~ the secondary conduit} connected directly to a work station 
to open
An additional tubular insert member is held within { HEAD ~ the principal conduit member } to open and close { TAIL ~ the secondary conduit } connected directly to a work station
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH