Needle valves are also used in {HEAD ~ situations} where {TAIL ~ the flow} must be gradually brought to a halt, and at other points where precise adjustments of flow are necessary or where a small flow rate is desired for medical use 
where
Needle valves are also used in { HEAD ~ situations } where { TAIL ~ the flow } must be gradually brought to a halt , and at other points where precise adjustments of flow are necessary or where a small flow rate is desired for medical use
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH