An apparatus for processing blood components comprises a centrifuge rotor (1) configured to be rotated about an axis of rotation. The rotor (1) comprises a portion (3) for receiving a separation chamber (4) in which blood components are centrifugally separated. The apparatus further comprises a pump (80) for pumping at least one of the centrifugally separated blood components from a separation chamber (4) into at least one collection bag (33), and a pressure sensor (70) for sensing pressure of blood components pumped by the pump (80). The apparatus is controlled by a controller (68) configured to control the pump (80) in response to pressure of blood components sensed by the pressure sensor (70).