Comparison of Measurement Methods for Pore Size Evaluation of Nonwoven Filter Media

The pore size characteristics are widely used in specifying and comparing filter media. Several methods of calculation have been prepared by researchers and some of these have formed the basis of well-known standards. In this paper five different methods of calculation have been compared. The experimental work has been performed on a rig fabricated in line with ASTM-F316 standard and results of careful measurements are reported. The results indicate that the values obtained by some methods are in close agreement with specification. The electron micrograph of filters revealed the random distribution of pore sizes and shapes leaving the use of some theories to question. The practicality and limitations of different methods have been discussed.