Sieve for treating fibrous material suspension suitable for producing fibrous material web used in paper machine, has specific number of screen layers which are connected to each other and comprised of perforations

摘要

The sieve consists of two screen layers (1,2) which are connected to each other and comprised of perforations (3,4). The perforations of the screen layer (1) are considerably smaller than that of the screen layer (2). The circumference of large perforation (4) is congruent with the segment (5) in the circumference of several smaller perforations (3).