962,386. Centrifugal classifiers. INSINOORITOIMISTO - ENGINEERING BUREAU R. T. HUKKI. April 8, 1963, No. 13847/63. Heading B2P. An open-topped vessel for the continuous hydraulic classification of pulps and suspensions of finely divided solid particles comprises a cylindrical top portion 1, a conical bottom portion 2, a pipe 13 for admitting feed, preferably by gravitational flow, a rotary impeller 4 for imparting circular motion to the feed in the portion 2 and for effecting discharge of the coarse size fraction via the apex of the cone, and braking means to eliminate the circular motion of the feed within an annular layer situated against the inside wall of the portion 1, whereby the fine size fraction is obtained in the form of an ascending, substantially laminar, continuous flow over the edge 10 of the portion 1 and is collected into a launder 11. The diameter of the top portion 1 may be smaller than that of the top of the conical portion 2. The braking means comprise vanes 8 mounted on an open-topped cylinder 8 which may be provided with a truncated cone 7 at its lower end. The braking means may be vertically adjustable and may be so designed as to provide a narrowing annular channel for the ascending fine fracton flow. The vanes 8 may be angularly adjustable. The coarse fraction may be washed by water admitted tangentially under pressure through a pipe 12. A manually or automatically operated valve 5 is provided for the discharge of the coarse fraction. A number of classifiers may be arranged in series or parallel.