measuring {HEAD ~ air pressure} in the air cup, the air pressure being directly related to {TAIL ~ the density} of the insulation 
measuring { HEAD ~ air pressure } in the air cup , the air pressure being directly related to { TAIL ~ the density } of the insulation
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH