A small hole is formed within each portion of the exposed membrane so that {HEAD ~ a differential pressure} can be applied across {TAIL ~ the membrane} without collapsing the membrane pores while effecting passage of liquid through the membrane 
applied across
A small hole is formed within each portion of the exposed membrane so that { HEAD ~ a differential pressure } can be applied across { TAIL ~ the membrane } without collapsing the membrane pores while effecting passage of liquid through the membrane
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH