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