A method for continuously washing packed red blood cells includes (1) transferring, at a first flow rate, packed red blood cells from a container to a separation device and (2) transferring, at the same time as the packed red blood cells, wash solution from a container to the separation device. The wash solution may be transferred at a second flow rate that is greater than the first flow rate. The wash solution mixes with the packed red blood cells within the inlet line of the separation device and dilutes/washes the packed red blood cells. The separation device separates the red blood cells from the wash solution and a supernatant. The method may then monitor the volume of washed red blood cells within the separation device and begin to extract the washed red blood cells into a red blood cell product container when a target volume is collected within the separation device.
