A main valve has {HEAD ~ a first chamber} on one side downstream from the metering valve, and {TAIL ~ the valves outlet} is connected to this first chamber 
A main valve has { HEAD ~ a first chamber } on one side downstream from the metering valve , and { TAIL ~ the valves outlet } is connected to this first chamber
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH