For a given source pressure, the loose fill insulation has {HEAD ~ a characteristic pressure drop} for {TAIL ~ a given density} 
for
For a given source pressure , the loose fill insulation has { HEAD ~ a characteristic pressure drop } for { TAIL ~ a given density }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL