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