Filter elements

摘要

A filter element (10) has an upstream-side filter layer (12) and a downstream-side filter layer (14). The downstream-side filter layer (14) is attached to the upstream-side filter layer (12). A non-woven fabric made of resin fibers (F) formed by a spinning process constitutes the upstream-side filter layer (12). The resin fibers (F) have an average diameter within a range of 2.5 µm and 10 µm. The non-woven fabric has a weight per unit area within a range of approximately 2.5 g/m 2 to 15 g/m 2 . The downstream-side filter layer (14) has a finer mesh than the mesh of the upstream-side filter layer (12).