A disposable blood separation set and a centrifugal blood processing system comprising a blood processing chamber adapted to be mounted on a rotor of a centrifuge a frustro-conical cell separation chamber in fluid communication with the processing chamber, the cell separation chamber having an inlet, a primary outlet and a side tap outlet adjacent the inlet. A valve that is responsive to centrifugal force (a “gravity” valve) selects between the outlet and the side tap outlet. The gravity valve is mounted on the rotor. When the rotor spins at high speed, the gravity valve may open the primary outlet and close the side tap outlet. When the rotor spins at a lower speed, the gravity valve may open the side tap outlet and close the primary outlet.
