Pressure/mass method to measure open porosity of porous solids

This work presents a method to directly determine the open porosity of porous solids, and more particularly those used in sound absorbing liners. The method is based on the measurement of four masses at four static pressures from which the open porosity and true mass density are deduced using the perfect gas law. The precision of the method in relation with the used experimental setup is studied, and a simple expression is derived to predict the experimental error in function of the bulk volume of the sample to test. For a given experimental setup, this simple expression can be used to select the amount of bulk volume to test to reach a given precision. The method and its error prediction are tested experimentally on different samples of theoretically known open porosity. Good correlations are obtained for low and high porosity samples.