using the measured air pressure to determine {TAIL ~ the density} of {HEAD ~ the insulation}; and 
using the measured air pressure to determine { TAIL ~ the density } of { HEAD ~ the insulation } ; and
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH