A minor amount of fluorocarbon vapor is also displaced as {HEAD ~ all air} is purged from {TAIL ~ the chamber} 
A minor amount of fluorocarbon vapor is also displaced as { HEAD ~ all air } is purged from { TAIL ~ the chamber }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL