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