A classifier rotor mounted for rotation about a rotor axis inside a classification chamber for separating a fines fraction includes a plurality of disks mounted in parallel, spaced-apart relation along the rotor axis and a plurality of classifier blades axially mounted between the disks at the disk periphery. A uniform influx fluid distribution tube disposed between the disks of the classifier rotor is connected to a vacuum source to remove the fines fraction. The uniform influx fluid distribution tube includes a plurality of perforations of varying sizes in the region between the disks to compensate for velocity and pressure variations, thus creating a uniform air flow along the entire length of the classifier rotor.
