STRUCTURE OF A HIGH-EFFICIENCY GLASS-FIBER FILTER MEDIUM

The analysis of the real internal structure of a high efficiency glass fiber filter medium was carried out to provide detailed structure dat a, e.g., for more realistic calculations of the filter performance. Th e procedure of the structure analysis is described in detail and the m ost important results are presented and discussed. The fiber diameter distribution was found to be constant throughout the HEPA medium studi ed. The fibers tended to be oriented perpendicular to the direction of air how, but there was no preferred direction of orientation within t he plane of the filter medium. The interfiber distance distributions i n parallel as well as in perpendicular orientation to air flow directi on were found to be of the expected exponential shape for distances > 1 mu m On the other hand, the frequencies of the distances <1 mu m inc rease and the exponential shape of the curves is no longer observed. ( C) 1997 American Association for Aerosol Research.