{HEAD ~ The chamber} is sealed upon purging of all the air and is maintained in {TAIL ~ a pressurized state} for a period of time 
is maintained in
{ HEAD ~ The chamber } is sealed upon purging of all the air and is maintained in { TAIL ~ a pressurized state } for a period of time
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH