Simplified Porosity Measurements

With the increasing importance of acoustical impedance and its relation to flow resistance and porosity in homogeneous porous materials, a simplification in the technique of porosity measurement seems in order. It is the purpose of this paper to describe a dynamic method of measuring porosity. The essential feature of the dynamic method is the use of the compliance of the air in the pores of the material to control the period of the free damped oscillation of a mechanical system. The dynamic method has the advantage of small temperature dependence and minimal time for a single measurement.