An automatic system and method for the separation of blood into component parts includes a conically shaped collection and separation bag (100), component bags (120 and 135) connected to the collection and separation bag (100), a sensor (145), valves (130 and 140) to control flow between the component bags (120 and 135) and the collection and separation bag (100) and a controller (165) for controlling the process. Blood is placed in the collection and separation bag (100) and is separated by centrifuging. The components are removed from the collection and separation bag (100) either directly or indirectly by the centrifugal force into the component bags (120 and 135). Flow of the components is directed by automatic opening and closing of the valves (130 and 140) in response to the position of the interface between the separated components determined by the sensor (145) or the elapsed time.
