Permeameters are instruments used to measure the permeability, or porous nature, of a material by determining the pressure drop across a sample as a fluid passes through it. By taking the sample’s thickness, area, flow rate, as well as the viscosity of the fluid, permeameters produce results expressed as ‘k,’ representing the material’s permeability in terms of the observed flow rate per unit pressure gradient per unit area. Used for a wide variety of commercial purposes, numerous different types of permeameters are available, including gas, liquid, microflow, and diffusion permeameters, all of which can be employed depending upon the type of material being analyzed.