In the wet characterisation of fine filter media, there has to be a balance between pore size and open area in order to optimise performance. Traditionally, Porometry has been used, but this is a secondary method where many assumptions have to be made to convert flow rates into pore size. Furthermore, variations between different instruments can occur depending on both the theory used and the operator using the instrument.

Aqueous flow rates, although less dependent on theory, is not a standardised procedure with many media manufacturers building their own systems. Consequently, it is very difficult to make meaningful comparisons for filter media.

To set up methodologies for pore size analysis and aqueous flow measurements that are primary methods whereby all measurements can be traced directly back to NIST without the necessity for the application of theories or computer modelling to derive and answer. The results were then compared to other characterisation techniques including computer modelling...