METHOD OF FILTERING A FLUID AND A FILTER MEDIUM THEREFOR

摘要

The present invention relates to a filter medium comprising a pre-filter layer (41), an intermediate layer (42), and a fine fiber layer (43). The pre-filter layer (41) comprises fibers having a diameter and a porosity P41; the intermediate layer (42) comprises fibers having a diameter and porosity P42, and the fine fiber layer comprises fibers having a diameter and porosity P43. The diameter of the fibers and the porosity P42 of the intermediate layer (42) is larger than the diameters of fibers and the porosities P41 and P43 of the pre-filter layer (41) and the fine fiber layer (43).