Fecha de publicación: 15/10/1990 Fuente: WIPO "bee" The filter arrangement incorporates at least one zig-zag folded filter-material arranged between the flow inlet and flow outlet, with each fold open to the flow inlet having a rounded base, the radius of which is 0.05-0.3 of the depth of the fold, whilst each fold open to the outlet flow ends in an acute angle. Each fold open to the flow outlet is fitted with an insert, consisting of a flat material having protruding deformations with perforations on either side.