A75 um thick polysulphone microporous membrane has an average porosity of e 0.35. pure water flux through the membrane is 35 m'/m h at a pressure drop of 2 bar at 25°c. the average pore size is estimated to be 0.8 um. calculate the tortuosity factor of the pores, the resistance to flow offered by the membrane and its water permeability. the viscosity of water at 25°c is 0.9 cp