These small valves are used to accurately regulate the flow of {HEAD ~ fluids} and gases at {TAIL ~ certain flow rates} 
These small valves are used to accurately regulate the flow of { HEAD ~ fluids } and gases at { TAIL ~ certain flow rates }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL