To enable reopening, a bypass system connects the upstream side of metering valve to the first chamber, while there is a manually operated closure for manually opening and closing off {HEAD ~ the bypass} to {TAIL ~ the first chamber} 
To enable reopening , a bypass system connects the upstream side of metering valve to the first chamber , while there is a manually operated closure for manually opening and closing off { HEAD ~ the bypass } to { TAIL ~ the first chamber }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL