Permeability of a porous, sheet like sample is determined using a device that is designed to measure the pressure differential between a first stream of fluid applied across an entire thickness of a test sample and a second stream of {HEAD ~ fluid} applied across {TAIL ~ an entire thickness} of a reference sample 
applied across
Permeability of a porous , sheet like sample is determined using a device that is designed to measure the pressure differential between a first stream of fluid applied across an entire thickness of a test sample and a second stream of { HEAD ~ fluid } applied across { TAIL ~ an entire thickness } of a reference sample
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH