This document specifies a measuring method for the distribution of thickness, area mass, gas permeability and collection efficiency in the filter medium, and applies to both woven and non-woven filter medium.

This document provides a method for sampling specimen (position, size and number) from the filter medium required to obtain its performance distribution accurately.

The purpose of this document is to provide more accurate information about the morphology of the filter medium for users, and not to compare grade the performance of the filter medium.