RECENT ADVANCES IN TEXTILES FILETRING MEDIA CHARACTERIZATION: COMPARISON AMONG MERCURY POROSIMETRY, VDI AND IMAGE ANALYSIS

摘要

In the filtration of the air by solid particles, the characteristics of the textiles used as filter media play a decisive role for plant performances. Particularly, the pore size distribution, the morphology within the thickness of the media, the number of holes per unit area and their uniformity are decisive factors. The four mostly commonly used methods for measuring the porous network of filter media are: bubble point testing; challenge test; mercury porosimetry and gas adsorption. Nowadays other techniques are available, for instance digital imaging based procedures able to realize a full morphological, morphometrical and a textural characterization of porous network constituting the filter media itself. Such an approach, relatively easy to implement and apply, together with the classical ones can strongly improve the "a priori" evaluation of filtration media performances. Aim of the present study is to compare the results obtained using different media filtering characterization approaches, as mercury porosimetry, VDI and image analysis with particular reference to textiles filter media commonly utilized for air filtration. The results are critically analyzed, compared and the correlation among the different techniques presented and discussed.