Abstract: A treatment chamber for purification and fractionation of materials suspensions, particularly fibrous suspensions under pressure, and wherein the treatment chamber includes a rotary screening drum provided with pulsation members, the drum also including screening holes located on the back-side of, or immediately behind, the pulsation members as viewed in the direction of drum rotation.

Abstract: An apparatus for effecting purification and fractional separation of a material suspension, which includes a screening assembly of the closed centripetal type comprising an outer annular chamber with a stationary outer shell and also an inward rotatable drum, together with an inner annular chamber which is radially outwardly defined by said first drum and radially inwardly by a second screening drum, an improvement in the efficiency of the separatory apparatus consists in providing means for creating pulsating waves in the suspension in association with said first rotating screening drum.