No. 843,222 filed Oct. 18, 1977, now U.S. Pat. No.4,185,629, entitled: METHOD AND APPARATUS FOR PROCESSING BLOOD, the disclosures of which are incorporated herein by reference.The previously utilized means, such as clamps and bolts, for clamping two platens together with a receptacle therebetween and with elastomeric linings between the inner side of one or both platens and the receptacle have not