Patent GB-1211942-A (GB)
Title: Cell washing centrifuge
IPC: B04B5/04
Filed: 1968-02-15
Abstract: 1,211,942. Centrifugal separators. IVAN SORVALL Inc. 15 Feb., 1968 [15 Feb., 1967; 5 Jan., 1968], No. 7567/68. Heading B2P. In a multi-speed centrifuge for treating liquid suspensions of biological materials, e.g. blood cells, in test-tubes 54, Fig. 2, which are pivotally mounted in circular array on the centrifuge rotor so that during centrifugation they are swung outwardly, decantation of the supernatant liquid from the test-tubes subsequent to centrifugation takes place under the action of centrifugal force when the tubes are maintained either parallel or at an angle relative to the rotor axis by a locking device 63, 64, 66, Fig. 5, while the rotor is rotating. The motor-driven rotor shaft 19 of the centrifuge extends into a casing 18 closed by a removable or hinged cover lid 21 to the bottom surface of which is connected an annular baffle 26 which cooperates with an annular lip 31 of an annular trough 29, also connected to the casing 18 or to the lid 21 as shown, for directing the supernatant liquid from the testtubes into the trough during decantation. Each test-tube 54, which may be made of glass, aluminium or stainless steel, is carried by a tube carrier 48 pivotably hooked at its upper end to a plate 44 secured by means of a stub 42, 43 to the top of a cylindrical hub 41 removably mounted on the shaft 41. The bowl 37 of the rotor is connected to a drive hub 36 secured to the shaft 19 by a set screw. Connected to the bottom of the hub 41 is an annular plate 56 provided with a collar 57 terminating in a flange 58 and with a pair of apertures through which extend drive pins 61 mounted in hub 36 and having tapered sides which during rotation of hub 36 urge the plate 56 downwardly thereby driving the plate 56 and hub 41 assembly. Alternatively, the drive may be effected by the hub 41 being a friction fit on the shaft 19. When the centrifuge is at rest, the tube carriers are suspended at a small (0‹-5‹) negative angle, as shown in Fig. 2, to the shaft axis by virtue of the lower portions of the carriers bearing against the collar 57 of the plate 56. During centrifugation, the tubes are swung outwardly until, as shown in dotted lines, they abut the upper end portion of the rotor bowl 37. The locking device 63, 64, 66 comprises an annular plate 63 provided with a flange 64 terminating in an inwardly extending locking rim 66. During the centrifuging operation, the plate 63 rests upon the bottom surface of the bowl 37 with rim 66 downwardly spaced from the paths of the bottoms of the tube holders 48. After centrifugation, the driving motor is shut down and the bowl 37 decelerates to a stop whereby the tubes descend to their original negative position as shown in Fig. 2. The plate 63 is then raised by means of a pivotable lift fork 72 having upwardly bowed knuckles 76 which, when the fork is actuated, move through an annular opening 77 in the bottom floor of casing 18 to raise an actuator ring 69 which in turn contacts pins 68 connected to the plate 63 and extending through apertures 67 in the bowl 37. The bowl 37 is again rotated and the normal outward movement of the tubes is prevented by a hook portion 53 or flange portion 52 at the bottom of each tube holder engaging locking rim 66 so that the tubes are maintained parallel to or at a small negative angle, Fig. 5, relative to the shaft axis. With the tubes in this position decantation takes place. The lift fork 72 during decantation is retained in the depressed position by hand or by a spring-actuated latch 82, as shown. Alternatively, solenoid or other electrical means may be provided to operate lift fork 72. After decantation, the cover lid 21 may be opened and liquid such as washing fluid, added to the test tubes for further treatment of the biological materials and successive centrifugation and decantation steps repeated. After a sufficient number of cycles lid 21 is opened and a knob 43 on the stub 42 is grasped and lifted so that the whole assembly of top plate 44, bottom plate 56, test tube holders 48 and test tubes 54 is removed as a separate unit from the centrifuge, with flange 58 on the plate 56 serving as a base for location upon a table or platform. In another embodiment, Fig. 9 (not shown), the test tubes are retained during decanting at a small positive angle relative to the rotor axis. In a still further embodiment, Figs. 10 and 11, a composite arrangement is shown in which the tubes are negatively (Fig. 10) or positively (Fig. 11) angled by the hook portion 53 on the tube holders alternatively and selectively engaging coaxial locking rims 66 and 66b on the plate 63. To facilitate alternating selective engagement, a removable ring 91, Fig. 12, may be slipped over the shoulder 57 of plate 56 to prevent the tube holders 48 from moving too far inwardly upon stopping of the motor so that the hook portions 53 are engaged only by the locking rim 66b. The most advantageous decanting speed may be determined by a variable speed control connected to the drive motor or by providing a microswitch 85, Fig. 2, which is actuated when lift fork 72 is depressed, the switch being connected to a suitable electrical speed control circuitry.