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