The POROLIQ™ is a liquid-liquid porometer (LLP) that determines pore sizes using the pressure-step stability method. Flat or hollow fibre membranes are soaked in isobutanol saturated with water. This liquid is displaced with water saturated with isobutanol, and the pressure required to empty a given pore size is given by the Laplace equation. The output is the pore size distribution and the pore volume associated with each pore size. 

• It can measure pore sizes in the range of 1 um to 2 nm (ideally). If there are larger pores, it may work unless the flow through them is so high that this signal drowns out the flow through smaller pores.
• It can measure flux vs pressure for membranes soaked in DI water saturated with isobutanol.

  It is easy to use, but some samples, such as those that swells in water, are difficult to measure.