A fluid processing device comprising: a controller; a centrifuge configured to receive and rotate a continuous-flow centrifuge chamber of a fluid flow circuit; a pump system configured to convey fluid through the fluid flow circuit; an optical detection assembly configured to monitor low- and high-g outlet conduits (L13, L12) connected to the centrifuge chamber and to transmit signals to the controller that are indicative of the nature of flow through the low- and high-g outlet conduits; and a pressure sensor configured to measure an inlet pressure of fluid flowing into the centrifuge chamber and to transmit signals to the controller that are indicative of the inlet pressure, wherein the controller is configured to execute a priming procedure including controlling the centrifuge to rotate the centrifuge chamber at an initial rotational rate, controlling the pump system to convey a priming fluid into the centrifuge chamber so as to convey air out of the centrifuge chamber via the low-g outlet conduit, determining whether the priming fluid is flowing through the low-g outlet conduit and, upon determining that the priming fluid is flowing through the low-g outlet conduit, controlling the centrifuge to increase the rate at which the centrifuge chamber is rotated so as to move air remaining in the centrifuge chamber toward the low-g outlet conduit, determining whether, at the increased rotational rate, the inlet pressure is less than a threshold value, a flow rate of the priming fluid through the low-g outlet conduit is decreasing, and a flow rate of the priming fluid through the high-g outlet conduit is increasing, and upon determining that, at the increased rotational rate, the inlet pressure is less than the threshold value, the flow rate of the priming fluid through the low-g outlet conduit is not decreasing, and the flow rate of the priming fluid through the high-g outlet conduit is not increasing, ending the priming procedure. a controller; a centrifuge configured to receive and rotate a continuous-flow centrifuge chamber of a fluid flow circuit; a pump system configured to convey fluid through the fluid flow circuit; an optical detection assembly configured to monitor low- and high-g outlet conduits (L13, L12) connected to the centrifuge chamber and to transmit signals to the controller that are indicative of the nature of flow through the low- and high-g outlet conduits; and a pressure sensor configured to measure an inlet pressure of fluid flowing into the centrifuge chamber and to transmit signals to the controller that are indicative of the inlet pressure, wherein the controller is configured to execute a priming procedure including controlling the centrifuge to rotate the centrifuge chamber at an initial rotational rate, controlling the pump system to convey a priming fluid into the centrifuge chamber so as to convey air out of the centrifuge chamber via the low-g outlet conduit, determining whether the priming fluid is flowing through the low-g outlet conduit and, upon determining that the priming fluid is flowing through the low-g outlet conduit, controlling the centrifuge to increase the rate at which the centrifuge chamber is rotated so as to move air remaining in the centrifuge chamber toward the low-g outlet conduit, determining whether, at the increased rotational rate, the inlet pressure is less than a threshold value, a flow rate of the priming fluid through the low-g outlet conduit is decreasing, and a flow rate of the priming fluid through the high-g outlet conduit is increasing, and upon determining that, at the increased rotational rate, the inlet pressure is less than the threshold value, the flow rate of the priming fluid through the low-g outlet conduit is not decreasing, and the flow rate of the priming fluid through the high-g outlet conduit is not increasing, ending the priming procedure. controlling the centrifuge to rotate the centrifuge chamber at an initial rotational rate, controlling the pump system to convey a priming fluid into the centrifuge chamber so as to convey air out of the centrifuge chamber via the low-g outlet conduit, determining whether the priming fluid is flowing through the low-g outlet conduit and, upon determining that the priming fluid is flowing through the low-g outlet conduit, controlling the centrifuge to increase the rate at which the centrifuge chamber is rotated so as to move air remaining in the centrifuge chamber toward the low-g outlet conduit, determining whether, at the increased rotational rate, the inlet pressure is less than a threshold value, a flow rate of the priming fluid through the low-g outlet conduit is decreasing, and a flow rate of the priming fluid through the high-g outlet conduit is increasing, and upon determining that, at the increased rotational rate, the inlet pressure is less than the threshold value, the flow rate of the priming fluid through the low-g outlet conduit is not decreasing, and the flow rate of the priming fluid through the high-g outlet conduit is not increasing, ending the priming procedure.