Abstract: Embodiments include a blood collecting system comprising a scale, a blood agitating system, a blood bag and a tube for extracting blood from a donor. The collecting system comprises, or is connected to, a processor for controlling the scale, the blood agitating system and the amount of blood being extracted from the donor. The processor is arranged to store one or more formulas for calculating an optimum amount of blood that can be donated. The processor can receive information regarding which formula to be used, the parameters necessary for the chosen formula. The processor is arranged to process the parameters in the chosen formula to calculate the amount of blood to be extracted. The processor is arranged to use the result of the calculation to control the collecting system to extract the calculated amount of blood and stop when the scale has detected that the calculated amount has been extracted.

Abstract: A cradle for use in blood donating processes comprises surface (2) which is intended to support a blood-collecting bag and to be rocked reciprocatingly on an axle (4) which extends perpendicularly to the surface, by means of a crank (5, 7). The cradle is provided with a weight measuring device (8) which functions to measure the quantity of blood that has flowed into the bag, and is also fitted with a clamping device (11) which functions to clamp-on or squeeze the hose such as to prevent blood from flowing therein and which is operable electromagnetically. The cradle is further provided with a control circuit (21) which is constructed to control at least the clamping device (11).