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