{HEAD ~ The flow rate} for {TAIL ~ both the test fluid flow system} and the reference fluid flow system is determined independently, by measuring a pressure drop throughout the flow system 
for
{ HEAD ~ The flow rate } for { TAIL ~ both the test fluid flow system } and the reference fluid flow system is determined independently , by measuring a pressure drop throughout the flow system
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL 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