Abstract: An apparatus for filtering liquids, especially for recovering fibers from white water, includes rotatable filter discs at least partially immersed in the liquid to be filtered, and a shaft wall connected to the discs forming a circular cylindrical filtrate chamber, which extends centrally through the discs. A rigid stationary partition wall extends in the filtrate chamber dividing the latter into at least two axial channels. The partition wall is spaced from the shaft wall and arranged such that all of said axial channels receive various fractions of filtrate, respectively. Filtrate discharge means is provided for discharging said fractions of filtrate respectively from the respective axial channels, such that the pressure prevailing in the filtrate of each channel is at least substantially as high as atmospheric pressure.

Abstract: A disk filter for filtering mat forming suspensions is provided with a hollow shaft for receiving a flow of fine fraction created by hydrostatic pressure difference between the suspension to be filtered and the fine fraction in the hollow shaft. According to the invention, each disc is provided with a number of fine fraction chambers communicating with the interior of the hollow shaft via respective holes in the circumferential wall of the shaft. Each chamber is arranged, such that it functions as a dropleg during movement upwards, with the result that the coarse particle (fibre) concentration of the created coarse fraction is increased.

Abstract: An apparatus for filtering liquids, such as fibre pulp suspensions, includes annular hollow filter discs each of which has two annular liquid pervious, opposed walls covered with filter material, spray nozzle means for cleaning the filter material, and means providing relative movement between the filter material and spray nozzle means. The annular opposed walls of each filter disc are only attached to each other at their radially outer ends, whereas they are spaced from each other at their radially inner ends, such that an annular opening is defined between the interior of the filter disc and a filtrate chamber extending centrally through the filter discs. The spray nozzle means extends from the filtrate chamber through the annular opening into each filter disc. As a result, an extremely pure fine fraction can be produced, clogging of the filtering material is efficiently counteracted, and the operative part of the filter material can be increased.