Abstract: A separation set for blood component preparation and similar separations for use in a centrifuge rotor, the set including a plate-like separation container made of a flexible material, an annular pinch valve which is mounted on and divides the separation container into a central section and an annular outer section, a first component container which is connected to the center of the separation container, a second component container which is connected to the circumference of the separation container, and a blood withdrawal tube for supplying blood to the outer section. The blood is separated in the outer section into plasma, buffy coat and red blood cells. Then the plasma is displaced to the first component container and the buffy coat to the central section where it is enclosed through the action of the pinch valve. The separation set with the pinch valve is then removed from the centrifuge and the red blood cells are transferred to the second component container.