Blood processing systems and methods with sensors to detect contamination due to presence of cellular components or dilution due to presence of plasma

A blood separation system comprising

• a device which, in use, operates to separate whole blood into red blood cells and plasma,
• a whole blood inlet line to convey a flow of whole blood into the device,
• a plasma collection line outside the device to convey a flow of plasma from the device,
• a red blood cell collection line outside the device to convey a flow of red blood cells from the device,
• a first sensing assembly including a first sensor in the plasma collection line operating to detect presence of at least one species of cellular blood component in the flow of plasma and generating a first output,
• a second sensing assembly including a second sensor in the red blood cell collection line operating to detect red blood cell hematocrit in the flow of red blood cells and generating a second output, and
• a controller operating to control flows in the plasma collection line and the red blood cell collection line based upon the first and second outputs.