The measurement of the Permittivity of fluids through porous media has generally been performed on a rather primitive level in comparison to related measurements: the flow of electricity and heat through conductors or diffusion of one material through another. For example: in the case of electric or heat flow a constant electrical potential or temperature difference is maintained across the material being testing, and the electron or heat flow measured. These quantities are related by what is termed a phenomenological relationship between forces and fluxes where the potentials are the forces and the flows the fluxes.
In contrast, fluid Permittivity is often determined for a porous media sealed to the bottom of a pressurized fluid-filled reservoir. There is little if any control of either forces or fluxes, but because the media under test generally serve in non-critical industrial applications where failure results in little possibility of a catastrophe, the results so obtained are adequate. However, with the advent of technological fabrics, membranes, and other porous media used in critical applications where failure can result in structural failure and even loss of life, more precise characterizations of fluid-flow potential through porous media is imperative. Among these technically-critical media are
In response to these technological requirements an Advanced Permittivity Testing Method has been devised wherein fluid forces and fluxes are separately and simultaneously measured under controlled conditions in accordance with phenomenological requirements to determine the Permittivity of porous media. The Advanced Permittivity Testing Method can emulate methods presently in use in the field of filtration and separation and allows direct observation of pore deformation under service conditions.