{TAIL ~ The gas} and vapor evolved in these zones passes upwardly through {HEAD ~ the vents} 94 into the vapor collection region 89 and is removed 
{ TAIL ~ The gas } and vapor evolved in these zones passes upwardly through { HEAD ~ the vents } 94 into the vapor collection region 89 and is removed
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH