US2906451A - Collection centrifuge - Google Patents

Description

Sept 29, 1959 9 J. L. TuLLls ETAL 2,906,451

COLLECTION CENTRIFUGE Filed April 12, 1955 l 9 Sheets-Sheet 1 Sept 29; 1959 J. L.. TuLLls ETAL 2,906,451

COLLECTION CENTRIFUGE Filed April l2, 1955 9 Sheets-Sheet 2 Sept. 29, 1959 J. l.. TULLls ETAL COLLECTION CENTRIFUGE 9 Sheets-Sheet 4 Filed April 12, 1955 I 1f /f Sept. 29, 1959 J, L, TULLls ETAL 2,906,451

COLLECTION CENTRIFUGE Filed April 12, 1955 9 Sheets-Sheet 5 Sept. 29, 1959 J, L TULLls ETAL 2,906,451

COLLECTION CENTRIFUGE Filed April 12, 1955 9 Sheets-Sheet 6 l' Ii i9 Ff! j?) ff l r .if

Sept. 29, 1959 J. L. TULLls ETAI- coLLEcTIoN CENTRIFUGE 9 Sheets-Sheet 'T Filed April 12. 1955 Sept. 29, 1959 J, TU| |S ETAL 2,906,451

COLLECTION CENTRIFUGE Filed April 12, 1955 9 Sheets-Sheet 8 Sept. 29, 1959 J. L. 'ruLLls ETAI- coLLEcTIoN CENTRIFUGE 9 Sheets-Sheet 9 Filed April 12, 1955 United States Patent COLLECTION CENTRIFUGE James L. Tullis, Newton, and Robert J. Tiuch, Roxbury, Mass., assiguors to Protein Foundation Incorporated, Cambridge, Mass., a corporation of Massachusetts Application April 12, 195s, serial No. 500,882

4 claims. (c1. zas-27) This invention relates to centrifugation and, more particularly, to centrifugal apparatus useful in the separation of the various components of animal blood, though lit vmay equally well be used in the separation of components, having dierent specific gravities, of other liquids.

In U.S. patent applications Serial Nos. 281,988, and 281,989, filed April 12, 1952, and of common ownership with the present application, now Patent No. 2,822,126, and Patent No. 2,822,315, respectively, are described both centrifugal apparatus and methods of separation of tremendous value in effecting separation of the cellular components of animal blood from plasma, as well as in the separation of the various protein constituents of plasma.

The present invention is directed to improvements in `such apparatus, which provide improved separation, sterility, and ease of operation. More specifically, it is a particular object of the present invention to provide .novel continuous feed centrifuge bowl structures for carrying out various separations of the elements of whole blood, that is, red blood cells, white blood cells, platelets and plasma which differ in specific gravity, as well as to separate such components from other liquids, and especially the separation of red blood cells from other components.

It is a particular feature of the invention that the centrilfuge bowl structures provided have interchangeable parts wherein desired bowl structures may readily be assembled.

Various other objects and features of the invention will become apparent from the following description of preferred embodiments thereof, together with the accompanying drawings, wherein:

Fig. 1 is an isometric view, partly broken away, showing the apparatus of the invention;

Fig. 2 is an exploded isometric view of a portion of the apparatus of Fig. 1,

Fig. 3 is an enlarged detail view, partly in cross section of a portion of the apparatus of Fig. l;

Fig. 4 is a partial cross-sectional view of the apparatus of Fig. 3, taken on the line 4 4 thereof;

Fig. 5 is an enlarged detail cross-sectional view of another portion of the apparatus of Fig. 1;

Fig. 6 is a diagrammatic view ofthe cooling system of i the apparatus of Fig. l;

Fig. 7 is a cross-sectional view showing one interior structure of the centrifuge bowl of the apparatus of Fig. 1;

Fig. 8 is a cross-sectional view showing a modified form of the structure of Fig. 7; Fig. 9 is a cross-sectional view showing another interior-structure of the centrifuge bowl;

Patented sept. 29, 1959 Fig. 10 is a cross-sectional view showing another interior structure of the centrifuge bowl;

Fig. 11 is a cross-sectional view of the structure of Fig. 1o;

Fig. 12 is a cross-sectional view showing another interiorstructure of the centrifuge bowl, and

Figs. 13-16 are diagrammatic views showing the operation of the bowl structures of Figs. 7 through 12.

In Fig. 1 is shown the general arrangement ofthe apparatus, and in particular the elevator mechanism for raising the centrifuge bowl structure into driving relationship with its driving mechanism. On the right hand, the driving mechanism, centrifugebowl, and supporting strncture are shown; in the actual apparatus these'would also be present on the left hand side, but are herein broken away so that the elevator mechanism can be clearly shown.

The elevator mechanism is mounted on main frame supporting plate 10 and is actuated by handles 12, which handles extend through slots 20 in the front panel 11 of the apparatus. Said handles form one leg of a rst bell crank pivoted at 14 on plate 10, the other leg of which is connected through link 15 to one leg of a second bell crank pivoted at 16 on said plate. The other leg of said second bell crank is connected by a short link 17 to elevator rod 21. When handle 12 is in raised position, it slips behind catch 18 in spring 19, which latter is pushed into slot 2d in front panel 11. Handle 12 is thereby releasably held in raised position during the centrifuging. The raising of handle 12, through the above described linkage system, causes elevator rod 21 to move upwardly, carrying with it a supporting assembly which consists of sliding elements 23 attached to said rods, supporting pins 24 mounted thereon, spring 2S and spring supporting rod 26 mounted on said elements. The slides 23 slide on tracks on elevator posts 27 aiixed to and extending downwardly from plate 10. Four adjustable stops 28, 28 are provided for limiting the upward travel of the supporting assembly of which three are shown, two of said stops 28 being mounted on plate 10 and two of said stops 28 on elevator posts 27. These are provided with threads so that they can be positioned as required. Y

On the right hand side of Fig. 1 is shown the centrifuge bowl, its driving mechanism, and its supporting structure. The latter supports the bowl and also holds the collecting receptacles (not shown).

The centrifuge bowl will be later more fully described, but in general includes a top bowl 30 of generally conical shape, a bottom bowl 32 also of conical shape, an intermediate ring 60 therebetween, and a compression arrangement including-outer compression ring 34 holding the two bowls and the ring together. The bowls and other elements which come in contact with blood are preferably of stainless steel with a silicone coating. The bottom bowl 32 is rotatably mounted on a base which consists of a tableA portion 36 with a cylindrical rim 38 removably mounted therein for directly supporting lower bowl 32. A frame 37 extends downwardly from table portion 36. Said table portion is supported on spaced apart pins 24 with frame 37 bearing against'spring 25 The driving mechanism for the bowl consists of a magnetic chuck 40 rotatably mounted on supporting plate 10 and driven from a suitable electric motor (not shown). The chuck 40 includes an annular bottom surface having mounted therein in suitable non-magnetic material, a plurality of magnets adapted to contact the upper surface of compression ring 34. A driving pin 48 is mounted in said annular bottom surface for engaging driving slot 49 in compression ring 34 to positively drive said bowl. To assemble the structure, frame 37 carrying table 36 is first placed on frame locating pins 24, as shown in Fig. 1. The elevator mechanism is then actuated by raising handle 12 until table 36 hits the outside stop 2S. Further slight raising of handle 12 brings the frame lin contact with inside stop 28', thereby compressing spring 25 and locating the top bowl 30 in proper relation to chuck 4 0.

Fig. 3 shows the detail of the' bowl hold-down assemblies whioh consist of a clamping dog 50, a compression s'prin'g 52, a locating pin 54 mounted on said dog, a supporting rod 56 on which said dog and spring are mounted, a cam 58 and an actuating lever 59. As shown' in Fig. 3, if lever 59 is rotated so that the ilat face of cam 58 (Fig. 4) is at the top in Contact with a lower surface of table 36, compression spring 52 will lift dog 50 away from lower ange 29 of bottom bowl 32. Pin 54 is provided in order to assure the centering of the bowl.

In assembling the equipment for operation, the parts of the centrifuge bowl are assembled as shown in Fig. 1, and the assembled structure is then clamped by dogs S (of which two are provided for each bowl). The bowl is then raised by the elevator mechanism, as already described, into the proper position with respect to chuck 40. Dog 50 is then released by moving levers 59 so that the bowl can be spun.

With the multiple piece centrifuge bowl as hereindescribed', it is important that a fluid tight seal be provided between the top and bottom centrifuge bowls and the intermediate ring. Thus, as shown in Fig. 5, the top bowl 30 has an outwardlyvextending annular flange 31 at its lower edge, and the bottom bowl 32 has a similar flange 33 at its upper edge. A supporting member for internal elements of the centrifuge, as hereinafter described, comp'rising an annular ring 60', is interposedl between the flanges, and suitable sealing means comprising O rings 62 are interposed between ring 60 and flanges 31, 33 respectively. Spacing rings 64 are also interposed between ring 60 and flanges 31, 33 radially inwardly of the O rings 62 to limit the movement of flanges 31, 33 toward one another, said spacing rings being of a dimension somewhat less than that of the uncompressed 0 rings 62. Thus, a predetermined overall dimension of the assembled centrifuge can be provided, yet with adequate sealing. The opposed flanges 31, 33 are urged together by outer compression ring 34 and an inner cooperating locking ring 66, the outer compression ring having an inwardly extending flange which fits over top bowl flange 31. The downwardly extending skirt of said compression ring is screw threaded on its inner surface to cooperate with the screw threaded outer surface of locking ring 66, the upper surface of said latter ring contacting the bottom bowl flange as it is screwed into place to clamp flanges 31, 33 together.

Figs. 7 through l2 show the centrifuge bowl structure with various interior arrangements, and Figs. 13-16 the operation of said bowl structures wherein the left half shows the bowl running for the collection of one blood component, and the right half the bowl stopped or decelerating for collection of another component. It will be noted that the outside of the bowl is the same in each case and only its interior structure has been changed.

As to the bowl structure common to all of the modiications best shown in Fig. 2, the parts of the bowl are assembled on a cylindrical flanged base assembly consisting of base member 35 with a surrounding tubular member 41 having an inwardly extending flange 43 positioned beneath the outer periphery of base member 35 to support said base member therein, said assembly being adapted to fit into an opening in table 36 with its outer llangey 45 interposed between said `table and removable 'rim 38 to support the base assembly on said table. The

upper surface of the rim 38 acts as a running surface for a sealing member 67 of low-friction material, said sealing member being supported between said rim and flange 29 by a skirt 63 thereon. A waved spring washer 69 and underlying flat washer 69 are provided interposed between said sealing member and said flange. Spring washer 69 controls the pressure therebetween when clamping ring 34 is tight (and hence when the bowl is properly assembled), with flange 29 in driving engagement with lower bowl 32. A suitable O ring seal is provided between member 67 and skirt 63.

The base member 35 has mounted centrally thereof an upstanding stationary feed tube housing 80, said housing having slidahly mounted therein a feed tube 82 with a compression spring 84 interposed between said feed tube and said base to normally urge said feed tube upwardly. The feed tube extends downwardly through base member 35 to a suitable connector so that blood from adonor or other reservoir may be fed to the centrifuge. An upstanding circular flange 39 is provided on the base, such flange being spaced between the inner and outer radial extent of the base. A plurality of openings are provided in said base in addition to said central opening for carrying away liquids discharged from the centrifuge to suitable glass or plastic containers, for example. Thus inner openings having downwardly extending tubes 86 are provided in base member 35 between its flange 39 and feed tube housing 3d, one or more openings 87 having tubes 87 are provided in said flange surface, and an opening 8'8' having a vent tube 88 is provided in said base outwardly of flange 39 within lower bowl 32.

In Fig. 7 is shown a centrifuge bowl structure especially adapted for separation of red blood cells from other blood components. ln this arrangement, the supporting element ring 60 forms a part of a central baille 100 with its annular edge positioned between flanges 31, 33 and extending radially inwardly. A tubular skirt 101 is positioned radially inwardly of said flanges and extends downwardly therefrom, said skirt having a conical portion 102 extending downwardly and inwardly from the lower edge of said skirt. An upwardly extending cylindrical portion 104 is also provided, said cylindrical portion being spaced inwardly from said skirt 101 and outwardly from feed tube S2 which in this arrangement extends to the upper wall of top bowl 30. Openings 106 are provided in the baille radially inwardly of skirt 101, and openings 108 in said skirt at its lower edge adjacent conical portion 102. The base member 35 is provided with an outer collecting ring 92 positioned by the outer surface of flange 39 and extending upwardly outside of skirt 102 and an i'n'ner collecting ring 94 positioned by the inner surface of llange 39 and extending upwardly in a direction between skirt 101 and the lower edge of conical portion 102. A vent tube 96 may be positioned in one of said openings 86.

The operation of the structure of Fig. 7 is diagrammatically shown in Fig. 13 wherein the left hand side of the drawing shows the operation with the centrifuge spinning and the right hand side with the centrifuge stopped. Thus, with the centrifuge spinning, blood fed upwardly through feed tube 82 passes radially outwardly to the outer side wall of upper bowl 30. The red bloodl cells, being the heaviest blood component, first fill the compartment formed by said wall and baflle 100. The excess plasma and other components can escape through open'- ing 106, downwardly along skirt 101, radially outwardly through opening 108 therein, and thence again downwardly between collector rings 92 and 94 until it escapes through tube 87 to a suitable container. When the centrifuge is stopped, the collected red blood cells flow downwardly through opening 106, and somewhat inwardly to conical portion 102 and thence, since centrifuge force no longer causes them to pass outwardly through openings 108, downwardly and outwardly through tube 86 to a suitable container.

`of top wall 114.

- The structure of Fig. 8 is in effect a simplified form of the structure of Fig. 7 above described and is particularly vuseful in separating white blood cells from red blood cells.

Thus, from a construction standpoint, its central baffle 109 is provided with a downwardly extending skirt 110 but no other structure, and the outer collecting ring 92 only is used.

In operation, the blood is passed through feed tube 82, and the red blood cells collect as described -above with reference to Fig. 13. As the upper bowl 30 collects more and more red blood cells, the other components escape over the inner edge of baffle 109 downwardly along skirt .110, outer collector ring 92, and outwardly through tube 87 to a suitable container. When the red blood cell com- Vpartment isrlilled, the input of blood is stopped with the ,centrifuge still running. The separated plasma or other liquid is then passed through feed tube 82 to wash as adapted for separating cellular components, for example whitecells from a mixture of white cells and plasma or platelets from a mixture of platelets and plasma. It is equally useful for concentrating any particular substance present in small quantity in a large volume of diluent. In -this structure, the supporting baffle 60 is provided with a 'central cylindrical member 112 extending upwardly and downwardly therefrom inside of collector ring 92. A vvtop wall 114 is provided for said member, and it has at its bottom edge an inwardly extending flange 116. The feed .tube 82 in this arrangement extends to the inside surface In the operation of this structure, as shown in Fig. l5,

'the mixture of platelets and plasma is passed upwardly through feed tube 82 and ows downwardly along member 112. The platelets are held along wall 112, while .the plasma passesV downwardly into and through tube 87.

The' flange 116 retains sufficient plasma to reduce the washing effect of the plasma on the platelets and thus aid in keeping them on side 112. When the collecting chamber, as formed by iiange 116, side wall 112, and top '114 has collected a sufficient quantity of platelets, the

centrifuge is slowly decelerated to permit the plasma held -by said flange to pass out of the centrifuge. The platelets are then removed from wall 112 by passing a suitable wash solution through feed tube 82 while the centrifuge is spinning. The centrifuge is then abruptly stopped.

Figs. l and ll show a centrifuge structure particularly adapted for red blood cell washing, as by glycerol. In 4this arrangement, the central baflle 120 is of dished shape, extending entirely across the centrifuge and has four openings therein, a central opening 122 of somewhat larger diameter than thatof feedtube 82, and three openings Hspaced outwardly therefrom, each of said three openings having mounted therein, asvby suitable nuts, a spacing tube 124 having its ange adjacent the upper surface of :baille 120. A cylindrical skirt 126 extends downwardly from said bafe between said central opening and said v openings spaced therefrom. An upper circular baie 128 having holes therein corresponding to said three openings is mounted onl spacing tubes 124 with its lower surface spaced from the lower bae 120 by the anges 'of said tubes 124, said upper baflle having its outer rim extendv`ing tol just short of the outer wall ofthe centrifuge. The

feed tube 82' extends through opening 120 inthe central baffle to the lower surface of upper bale 128. -A cylindrical skirt 129 surrounds the openings in the upper battle and extends upwardly toward the top wall of 4upper bowl 30. This arrangement in effect forms a composite baffle having a central recess into which feed tube 82 extends, with radial passages extending outwardly to a point on the top surface of the bafe adjacent the inner surface of the top bowl 30, and axial passages extending therethrough displaced from the axis of the centrifuge bowl. The upper'cylindrical skirt 129 is spaced outwardly from said displaced passages and the lower skirt inwardly therefrom. Downwardly extending tubes 125 are provided mounted within two of said spacing tubes 124 and an upwardly extending vent tube 127 within the third. Said downwardly extending tubes 125 are positioned radially inwardly of outer collecting ring 92 and outwardly of inner collecting ring 94. Downwardly extending skirt 126 is positioned radially inwardly of inner collecting ring 94.

The operation of the structure of Figs. 10 and ll is shown in Fig. 14. The blood is passed upwardly through central feedv tube 82 and outwardly through the radial passages of the central baille. The red blood cells, as before, collect and the other blood components pass over the top of skirt 129, downwardly through tubes 125 and along the inner surface of outer collecting ring 92 and thence through tube 87 to a suitable container. When the red blood cell compartment is filled with red blood cells, the flow of blood through feed tube 82 is stopped and a glycerol solution is passed through said tube to glycerolize the red blood cells, the glycerol being of lighter density than the glycerolized cells, rises to the inner axis of the centrifuge and overflows. After the cells have been glycerolized, the centrifuge is decelerated and the glycerolized red blood cells will then pass radially inwardly through the radial passage in the central baille and dowriwardly through central opening 122 and tubes 86 to a suitable container. The glycerolized red blood cells may then be frozen and may be preserved in that state.

Whenever it is desired, then, to use the so preserved glycerolized red blood cells, they are deglycerolized by centrifuging. Thus, they are passed upwardly through central feed tube 82, and outwardly through the radial passages of the central baffle and are maintained adjacent the outer wall of the centrifuge. A washing liquid is then passed through feed tube 82 and deglycerolizes the cells, -the washing liquid and glycerol passing over the top of upper skirt 129, downwardly through the displaced tubes 125, and thence through tube 87 to a'suitable container. The red blood cells can be washed by as much liquid as desired, and such liquid will pass through the collected rnass of red blood cells before being discharged.

When the centrifuge is decelerated, the collected red blood cells will pass radially inwardly through the passages in the central baflie, and downwardly through central opening 122 and tubes 86 to a suitable container.

This structure is particularly effective in providing washing of a material collected therein by any desired quantity of sterile washing liquid. Thus, such closed-sysmounted on said element and extend outwardly and upwardly therefrom forming passages extending from the inner surface of said element between its flanges to a point closely adjacent the inner surface of upper bowl 30 about midway up its side wall. -Holes 137 through sd element -132 are positioned 'closely adjacent the' pper Surface of central baffle 13 0; An axiallyvdisp'lac'ed feed tube 1,38 extends upwardly frorn tube 86 in said base beyond lower flange 136 to a point closely adjacent upper flange ,134. The usual feed tube 82 extendscentrally upwardly to a point closely adjacent the top wall of bowl 3 0, and outer collector ring 92 extends upwardly and radially outwardly of the downwardly extending portion f element 132.

In the operation of this structure, blood is passed upwardly through central feed tube 82 as before, and the yred cells collect in the compartment formed by the side wall of upper bowl 30, with the plasma and other c ornvponent's passing downwardly through openings 137 along element 132 and collecting ring 92 until they are discharged through tube 87. As shown in Fig. 16, the red cells are then washed by plasma or otherl liquid by passing said liquid upwardly through displaced feed tube 138. From the top of said feed tube, it rno'ves radially outwardly between flanges 134, 13 6, and thence through jet tubes 135 into the collected red blood cells, which `remain collected at the outer edge of the upper bowl 30 above baille 1-30, while the wash liquid, being of lower specific gravity, passes thro-ugh openings 137 downwardly along the inner surface of element 132 andl collecting ring 92 into tube 87 from whence it discharges into a suitable container. When the centrifuge is deceler'aed, the collected red blood cells flow downwardly through openings 137 to opening 86 in base member 35 and thence to a suitable container. Valves are used so that the plasma, the wash liquid, and the red blood cells canbe collected separately. p

This structure can also be used without a wash step by verlling the capacity of the red cell collection compartment.

Aswill be apparent from the above description of the various types of centrifuge bowl structures shown in Figs. 7-12, the common centrifuge elements may be assembled with a variety of internal centrifuge elements to provide separation of the cellular components of blood or other biological fluids, such as milk. Also, the separationl of many other liquids, emulsions, and suspensions maybe accomplished by these centrifuge structures, since a difference in the specific gravity of the components to be separated is all that is required. Furthermore, inore than one component may be rapidly separated by using more than one centrifuge. Thus, with the twol unit arrangement as shown in Fig. l, one of the centrifuge bowls may be used to separate the red blood cells, and the plasma with other components may be passed directly to the second centrifuge bowl to separate a further component. This arrangement could be readily extended to separate continuously even more components by using more centrifuge bowls assembled with the proper interior elements.

For stability of the separated blood components', it is important that the blood be kept cool, and that it be cooled before it passes from the donor into the centrifuge. Thus, as shown in Fig. 6, a refrigeration unit is associated with the apparatus both to cool the blood before it enters the centrifuge bowl and to air cool the compartment housing the centrifuge assemblies. Freon or other refrigerant is compressed in compressor 70, cooled in after-cooler `7 1, passed through receiver 72 and drier 73 and split linto two streams shown in the drawings as 74 and 75. Stream 74 is expanded and cools bath coil 76 which cools the blood from the donor prior to sending it to the centrifuge operation. The expanded-refrigerant then passes through back pressure regulator 77 and thence back to the compressor. Stream 75 passes through evaporator 78 where it cools the air inside the apparatus around the bowl. It then returns to compressor 70. The bath coil is at a higher temperature than that in evaporator 78. Thus the pressure of the refrigerant is always controlled in line,74,by regulator 7'7 (since the pressure in the bath coilY will be higher than that in' evaporator 78). The' solenoid 79 is actuated by the them-@Stat and opens' when the i; temprature rises.

The compressor runs continuously, and if there is no load on the system, it merely discharges into the receiver 72. By this arrangement it is possible to use a single cornpressor to provide two different temperatures which are controlled independently of each other.` I

l To summarize the operation of the above described apparatus,- assuming that blood is to be taken from a donor and that the red cells are to be removed therefrom, the centrifuge bowl is rst assembled as shown in Figs. 7-12. Suitable containers are then connected to its outlet tubes and it is then sterilized with steam. It is then mounted on table'36 as shown in Fig. l. The elevator mechanism is then operated to raise the centrifuge bowl upwardly to its driving mechanism, and dogs 50 are then released so that the bowl will be released with lower bowl 32 in driying contact with flange 29 and upper bowl 30 seated in chuck 40 and held therein by magnets 44. The chuck 40 is then rotated to spin the bowl. Blood from a `donor is first passed through aresin column or a reservoir of any desired anti-coagulant solution to prevent coagulation, then cooled, and finally passed into the spinning centrifuge. The red blood cells will collect as above described until they ll the red cell compartment. During this time, the plasma and other blood components pass through the centrifuge into their container. When the red c ell compartment is filled, the centrifuge is decelarated and the red cells allowed to drain into another container. l

The centrifuge bowl is then stopped and disengaged from its driving mechanism by clamping dogs 50 to pull it away from chuck 40 and then lowering it by the elevator mechanism. The containers may then be removed and the centrifuge bowl taken apart for cleaning. p

Thus, it is apparent that the invention has provided a novel apparatus for separating components from blood during the actual phlebotomy, which apparatus results in improved separation, closed-system sterility and easeof operation. Various modifications of the apparatus, not herein disclosed, within the spirit of the invention and the scope of the appended claims will occur to` those skilled in the art.

We claim:

l. A centrifuge comprising a bottom bowl having a bottom central opening therein, a side wall, and an outwardly extending annular flange at the upper edge of said wall, a stationary base positioned beneath said central opening, sealing means interposed between said base and said bottom bowl, a to'p bowl having' a top wall, an outwardly and downwardly flaring conical side wall', and an outwardly extending annular flange at the lower edge of said wall, an internal centrifuge elementl having a central bale consisting of a generally flat circular plfate shape with its annular edge Positioned between said' opposed flanges and extending radially inwardly thereof, and a tubular skirt spaced radially inwardly fromv itsV annular edge and extending downwardly therefrom, clarn'ping means for clamping said flanges toward4 one another into firm pressure contact with said central baffle to seal' said centrifuge, stationary feed means extending upwardly from said base centrally through said bottom opening" for feeding liquid into the centrifuge at a point adjacent4 top wall, and means disposed below said bottom opening for collecting liquidV discharged from the centrifuge, said centrifuge being adapted for rotation about a vertical axis, whereby liquids discharged from said centrifuge during spinning thereof may be collected' separately from liquids dischargedv when said centrifuge is stopped.

2. A centrifuge as claimed in' claim 1, wherein said tubular skirt further includes a conical portion extending downwardly and inwardly from its lower edge and having a centralV opening, and an aperture through said tubular skirt adjacent its lower edge and the upper edge of said conical portion; A

3. A centrifuge as claimed in claim 2', wherein said means for collecting liquid discharged' from the centrifuge includes an outer collecting ring extending upwardly from said base beyond the lower extent of said tubular skirt and spaced radially outwardly therefrom and lan -inner collecting ring extending upwardly from said base and spaced radially inwardly from said tubular skirt and -radially outwardly Ifrom the inner edge of the central opening in said conical portion, and openings through said base between said inner and outer collecting rings, and between said inner collecting ring yand said lfeed means.

4. A centrifuge as claimed in claim 3, wherein said central bale extends radially inwardly of said tubular 19 skirt and includes an opening therethrough spaced radially inwardly of said skirt, and a second tubular skirt spaced radially inwardly from said opening and extending upwardly, said second skirt being spaced radially outwardly from said stationary feed means.

References Cited in the tile of this patent UNITED STATES PATENTS

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