In one aspect, the invention is a device for controlling a flow of {HEAD ~ a fluid} moving through {TAIL ~ a pipe} 
moving through
In one aspect , the invention is a device for controlling a flow of { HEAD ~ a fluid } moving through { TAIL ~ a pipe }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL