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