The aim of the research work presented in this paper was to improve the already developed reflected-light method [W. Koschutnig, G. Mauschitz, W. Höflinger, Charakterisierung der Oberflächenbehandlung und des Verstopfungsverhaltens von abreinigbaren Staubfiltermedien mittels Bildanalyse, CIT 76, 2004, 10, 5 pp.] to get a structure parameter of cleanable non-woven dust filter media, which can give information about the particle penetration. To reach this goal transmitted-light is used instead of reflected-light. By that way images with higher contrast will be achieved which enable to define a mean hydraulic diameter for the pores near the outer surface of cleanable non-woven dust filter media.
Experimental measurements were carried out which prove that the mean hydraulic pore diameter can be a measure for the particle penetration of a filter medium. The pore volume equivalent, which can be used as a measure of the dust storage capacity of the filter medium can also be detected by the transmitted-light method.