{HEAD ~ The pressure} in {TAIL ~ the tube} is then reduced to below 500 millitorr but not less than 150 millitorr 
{ HEAD ~ The pressure } in { TAIL ~ the tube } is then reduced to below 500 millitorr but not less than 150 millitorr
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH