Freezing Plasma in 5-Litre Bags for Storage and Thawing for Use

Abstract. Plasma, in 5-litre polyethylene bags, is frozen in the form of rectangular blocks by means of a special freezer. Refrigerated by sealed single-stage condensing units, this will freeze two bags (10 I) of plasma in 75 min. The bags are filled by the use of a 'flow inducer' pump, controlled by contacts on a balance. The blocks of frozen plasma, packed in cardboard containers, can be stacked closely with great economy of cold storage space. The blocks may be thawed in the bags on heated, inclined shelves, allowing the plasma to drain off as it melts.
The development of this system for handling plasma would not have been possible without the collaboration of the staff of many laboratories and manufacturers and of the Department of Health and Social Security. In particular, I am indebted to Dr. W. d'A. Maycock for advice in many aspects of the work and to Mr. A. L. Jackson and to Mr. F. W. B. Smith for extensive technical assistance; also to Dr. W. J. Jenkins and to Mr. R. Kirkham for their method of syphoning plasma for transfer to bags and for their part in the user trials.