Re {HEAD ~ opening} of {TAIL ~ the main valve} is accomplished with the aid of a bypass system connecting the upstream side of the metering valve to the main valves first chamber 
of
Re { HEAD ~ opening } of { TAIL ~ the main valve } is accomplished with the aid of a bypass system connecting the upstream side of the metering valve to the main valves first chamber
OTH HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH