Patent GB-1194896-A (GB)
Title: Apparatus for Centrifugal Particle Separation and Removal
IPC: B04B5/04
Filed: 1967-09-19
Abstract: 1,194,896. Centrifugal separators. BECKMAN INSTRUMENTS Inc. 19 Sept., 1967 [27 Oct., 1966], No. 42563/67. Heading B2P. In the rotor of a centrifuge for separating particles in suspension or solution in a liquid, upper and lower portions of a receptacle for holding the liquid to be centrifuged are interconnected by a passage which provides particle-sedimentation paths which are short compared with the sedimentation paths within the receptacle so that particles in the passage sediment more rapidly than particles in the receptacle to set up an hydrostatic imbalance between the liquid medium contained in the receptacle and that in the passage causing liquid to automatically recirculate through the receptacle and the passage. In Fig. 2, the centrifuge rotor is formed with a circular row of spaced cavities 36 in which sample-containing capped tubes 38 are placed. Each tube is provided with a conduit 42 connecting upper and lower portions of the tube interior. In operation, due to the smaller aross-section of the conduit 42, the liquid in the latter clears more rapidly than that in the tube 38, the sediment deposited against the radially inner wall of the conduit sliding down into the tube 38 towards the deposit 46 formed therein. The liquid in the conduit thus becomes less dense that the suspension or solution in the tube and is displaced upwardly out of the conduit by suspension or solution entering at the bottom of the conduit so that a continuous circulation is established hastening the separation process. In a modification, Fig. 3 (not shown) the conduit is in the form of a helical tube disposed on the external or internal wall of the tube. In another modification, Fig. 4a, the conduit 42b is defined by the space between the radially inner wall of the tube 38b and a partition 50 parallel to that wall. In Fig. 5, a batch-type centrifuge rotor comprises a bowl 62 having a frusto-conical cavity, the upper portion of the wall 70 of which is recessed to provide a peripheral sedimentation pocket 72. A partition 64 inserted in the bowl cavity defines with the wall 70 a short annular sedimentation passage 84 which is in communication with the space inside the partition through holes 78 in the upper portion of the side wall of the partition and through grooved passage ways 82 and a central hole 80 in the bottom wall of the partition. In operation, the particles deposited on the walls of the partition and bowl travel upwards towards the pocket 72 and the denser liquid will travel from the inside of the partition through the holes 78 and force the less dense liquid in the passage 84 downwardly and through the passageways 82 and hole 80. In a modification, Fig. 6, the sedimentation pocket 102 is formed between the bowl 100 and a depending flange 122 of the cover 120 which has a sloping wall 124 parallel to a wall 106 of a partition 104 and defining therewith a space in which are disposed frusto-conical discs 116 providing a series of sloped, annular, short sedimentation passageways 126. The discs 116 are held in a support ring 114 which is mounted on the wall 108 of the partition 104 and is formed with holes 118 providing fluid communication between the passageways 126 and a hole 112 in the partition wall 108. Openings 110 are provided in the lower edge of the partition 104 for the outward passage of the denser liquid which will displace the less dense liquid in the passageways 126 upwardly.