A measurement method of pore size evaluation of filter fabric

A measurement method for pore size evaluation of filter fabric is introduced in this article, based on the principles of capillary flow and hydrostatic pressure in a liquid. The bubbling pressure difference is controlled by the applied gas pressure and the depth of liquid. Comparing with the existing bubble pressure test method, the specimen is initially placed vertically with a given liquid and air on each side. A pore diameter of the largest pore and a mean pore size are determined at each pressure instead of the exclusive initial bubble point pressure and open bubble point pressure. Several random mean pore sizes are measured by a designed instrument using this method and the mean value is regarded as the equivalent pore size of the tested specimen. Scatter range of measurement values of pore size is evaluated by Type A uncertainty. Experiments are conducted on several kinds of filter fabric. The results show that the uncertainty values are all less than 3.00, which validates the stability and reproducibility of this method for the measurement of pore size.