Abstract: Pressure sorter for the preparation of fiber suspensions obtained from waste paper, with a screen surrounding a rotor, a supply chamber between rotor circumference and screen as well an accepts chamber outside the screen and with profiled elements provided at the circumferential surface of the rotor for generating positive and negative pressure pulses, whereby in order to achieve good sorting results as well as a long service life of the screen, a rotor peripheral surface sector is provided between two profiled elements following one another in circumferential direction of the rotor, in every axial section of the circumferential surface of the rotor acting on the screen, this rotor peripheral surface sector being part of a peripheral surface area parallel to the screen inlet side, wherein--measured in circumferential direction of the rotor--the length of each profiled element is at least approximately equal to the length of the following rotor peripheral surface sector, the length of the latter, however, bein