Abstract: A composite of interconnected bags comprises a blood collecting bag, a preserving liquid bag, and a blood plasma bag. The interior of the bag body of the blood collecting bag is divided by a partition strip into an empty space and an empty space of the shape of a strip, with the two empty spaces mutually communicating near the end part of the partition strip. The blood collected in the blood collecting bag is centrifuged. The upper layer of blood plasma resulting from the centrifugation is discharged via a tube to the blood plasma bag. Then, the erythrocyte preserving liquid in the preserving liquid bag is advanced through the tube, the empty space, and a connecting part and added upwardly from below to the concentrated erythrocyte left behind the empty space. The erythrocyte preserving liquid, without being stirred, is allowed to ascend and mingle with the concentrated erythrocyte with the elapse of time.

Abstract: A blood separator having: a blood bag pressurizing section for retaining a centrifuged blood bag and pressurizing the same at a predetermined pressure; a retention/measurement section for retaining at least two separation bags connecting with the blood bag via tubes and capable of receiving separated blood components, and measuring the weight of the separation bags; limiting devices provided at intermediate portions of the tubes between the blood bag and the separation bags to limit the flows of liquids in the tubes; a detector for detecting the level of an interface between components of blood in the blood bag retained in the blood bag pressurizing section; a moving device for moving the detector relative to the blood bag; and a controller for controlling the limiting devices while receiving, as an item of control information, detection information from the detector and/or measurement information from the retention/measurement section.

Abstract: A tube assembly is provided which includes a tubular body of rigid resin having an open end and provided with a substantially annular frangible portion and a plug of flexible resin mounted in sealing fit on the tubular body for closing the open end.