US3244362A

US3244362A - Centrifuging apparatus and fractionating system

Info

Publication number: US3244362A
Authority: US
Inventors: George N Hein
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-06-24
Filing date: 1963-05-03
Publication date: 1966-04-05
Anticipated expiration: 1983-04-05
Also published as: UST955355I4; FR1397578A; GB878606A; US3297243A; GB1044430A; DE1296842B; US3244363A; FR1448431A; GB976206A; DE1295889B; GB993114A; US3297244A; DE1598537A1; GB976207A; DE1150534B

Description

April 1966 G. N. HElN 3,244,362

CENTRIFUGING APPARATUS AND FRACTIONATING SYSTEM Filed May 5, 1963 5 Sheets-Sheet 1 INVENTOR.

650F615 M ////V ,5, WM Ma April 5, 1966 G. N. HElN 3,244,362

CENTRIFUGING APPARATUS AND FRACTIONATING SYSTEM Filed May 5 1963 3 Sheets-Sheet 2 u V a a n A TTO/P/VEYS April 5, 1966 G. N. HElN 3,244,362

CENTRIFUGING APPARATUS AND FRACTIONATING SYSTEM Filed May 5, 1963 3 Sheets-Sheet 5 IN VEN TOR. 655/966 /l/. A V/I United States Patent 3,244,362 CENTRIFUGING APPARATUS AND FRAQTIGNATENG SYSTEM George N. Hein, 331 Chesham Ave., San Carlos, Calif. Filed lVlay 3, 1963, Ser. No. 277,759 20 Claims. (U. 233-27) This application is a continuation-in-part of my pre viously filed copending applications Serial No. 822,561, filed June 24, 1959, now Patent No. 3,096,283, granted July 2, 1963, Serial No. 192,709, filed May 7, 1962, and Serial No. 268,396, filed March 27, 1963.

My present invention relates to the convenient and accurate centrifuging and fractionating of large or small batches of liquid, and, more particularly, to apparatus, liquid receptacles and a system as well as technique therefor. While my invention has particular application to the centri-fugation and fractionating of many liquids in totally different environments, this disclosure will be devoted primarily to an application by which whole blood is separated into its various constituents.

In clinical and industrial laboratories, it at times becomes necessary to clarify liquids, or to harvest precipitates therefrom, by centrifugati-on. Existing equipment will do this task with varying degrees of efficiency and ac curacy. However, the following shortcomings predominate:

(1) In one form of apparatus in which liquids are continuously fed into a spinning and somewhat conventional rotor, heavier particles will collect in the rotor while the lighter mediums are adapted to overflow. Naturally, the efficiency of this operation will be contingent on the rate of liquid feed and rotor speed. When the batch of liquid has been entirely fed into the rotor, only a small amount of precipitates may be contained thereby whereas a large amount of filtrates may be present which would lie below the overflow rim of the rotor. Under these circumstances, no feasible path remains for expelling the residual filtrates, without disturbing the interface of the precipitates. This would also be true in the event it were desirable to centrifuge a batch of liquid which was smaller than the overflow capacity of the spinning rotor.

(2) The strata of centrifuged liquids ordinarily cannot be observed in conventional spinning rotors.

(3) In accordance with other conventional techniques, small batches of liquids are centrifuged in test tubes which rotate around a vertical axis. The efficiency of this operation depends on the character of the liquid and the speed and time of rotation. If the precipitates of the liquid tend to cake and form a firm interface between its supernatants, a fair degree of separation can be achieved by decanting or pipetting one from the other, after rotation has stopped in a gentle manner. However, if the precipitates of a liquid are of only slightly greater specific gravity than its supernatants, then a firm cake is generally not formed. In this case, when tube rotation is stopped (even slowly), the extra gravitational forces on the components of the liquid cease. At such time, vibration diffusion and convection would tend to remix the liquid and very poor separation is accomplished.

My present invention has for one of its primary objects the provisions for a centrifuge apparatus which will largely overcome the above shortcomings of conventional units, and at the same time, provide for convenient and accurate centrifuging and fractionating of large or small batches of liquid.

Another object is to provide a centrifuging apparatus for use in obtaining a sharper fractionation by visibly and manually controlling the discharge of a portion of the liquid from the main body of a centrifuge container.

A further object is to provide a centrifuge which permits the observation of the accumulation of precipitates and at such time as the desired degree of separation occurs, the filtrates remaining in the liquid containing receptacle can be precisely expelled and collected without taking precipitates.

My invention further contemplates a fractionating system and technique as well as receptacle which contribute to the practice of this invention and as a result of which the foregoing objects partly ensue.

Other objects and advantages will become apparent from the following detailed description of the invention which is to be taken in conjunction with the accompanying drawings illustrating several somewhat preferred as well as exemplary embodiments thereof and in which:

FIG. 1A is a reduced elevational view of a centrifuge incorporating the teachings of my invention; i

FIG. 1 is a diagrammatic sectional view of the centrifuge during the initial stages of operation at which fractionation of the liquid to be separated is taking place;

FIG. 2 is a fragmentary sectional view similar to FIG. 1 showing the centrifuge of that embodiment during another stage of operation at which the lighter constitu ents are expelled from the container and then collected;

FIG. 3 is a similar fragmentary sectional view of the rotor supporting a container and collector in accordance with another embodiment of my invention which advantageously provides for continuous flow centrifugation; and

FIG. 4 is still another similar fragmentary sectional view of an alternative form of centrifuge rotor as well as another embodiment of container and collector.

Referring now to the embodiment of my invention illustrated in FIGS. 1, 1A, and 2 a centrifuge 10 includes a rot-or 12 drivably coupled with motor 14 both of which are mounted by the supporting stand 16 which also conveniently mounts the hydraulic network 18 the purpose of which will be described shortly. The motor output shaft 20 is substantially tubular in configuration and is suitably journaled in the stand 16 'by means of

bearings

22 and 24. The lower end of the shaft 20 extends into the reservoir 26 of the hydraulic network whereas the upper end fixedly supports the rotor 12.

The rotor 12 serves to accommodate a receptacle during the centrifugation process which conveniently contains the liquid to be separated and a collector for thelighter constituents expelled during the process. Thus, the rotor 12 includes the bowl 28 which is connected directly to the upper end of the motor shaft 20 by means of the threaded connection 30. The bowl contains a central coaxial chamber 32 which communicates with the internal bore 34 of the tubular motor output shaft 2% as 'well as a pair of diametrically opposed radially extending bores 36. Each of these bores includes upwardly extending passage 38 extending transversely therefrom out through the upper face of the bowl.

Installed in each of the bores 36 is a spring biased weight 42 which is shiftable radially under the action of centrifugal forces and adapted to move inwardly upon reduction of centrifugal forces to thereby reduce the tendency of the separated liquid that remains in the receptacle to overflow. The weights 42 are biased inwardly by means of the springs 44 the outer end of which bear against a plug 46 which is threa-dedly inserted in the outer end of the radially bores 36 by means of complementary threads tapped into the bore.

Overlying the upper bowl face of the bowl 28 is a relatively thin substantially flexible diaphragm or boot 48 which when inflated is adapted to facilitate the collection of the lighter constituents of the separated liquid. The circumferentially extending periphery of the diaphragm 48 is clamped to the associated surfaces of the bowl 28 by means of the ring 50 threaded onto mating threads appearing on the bowl 28.

Within the recesses of the bowl 28 as now defined by the diaphragm 5,8- and ring 50, is a container, receptacle or bag 52 into which the liquid to be centrifuged and separated is placed and eventually fractionated into its constituents. This container 52 is held in position by a ring 54 threaded onto the ring 58.

Reverting back to the container 52, which forms an auxiliary part of the rotor 12, it will be appreciated that three plastic parts are included each of which are heat sealed together. Thus, a base 56 is included and as will become evident, is preferably of a relatively thin flexible plastic material. The top 58, on the other hand, is formed from a relatively clear rigid plastic which should be sufficiently transparent to permit the interior of the receptacle 52 to be viewed through the window provided by the ring 54. In this connection, it is desirable that the concentrically arranged inverted dish or cup 60 also be formed from a relatively clear rigid plastic material. The base of the dish 60 is provided with a central opening 62 which facilitates the introduction of liquid to be separated into the container 52 through the central opening on as well defined by the upstanding collar 66 extending from the top 58. This collar together with the top and opposed. surfaces of the dish 69 define a concentric annular collection chamber 68 for receiving the lighter constituents of the liquid to be separated that are expelled from the main liquid chamber 79 defined by the base 56 and top 58.

The hydraulic network 18 associated with my centrict'uge serves to flex the base 56 of the bag 52 during the centrifugation particularly when separation has fully been developed in order to expel the lighter radially inwardly disposed liquid constituents out through the collar (:6 into the collection chamber 68. Accordingly, the hydraulic network 18 as stated includes a reservoir 26 for the hydraulic liquid 72. Disposed within the reservoir 26 is a pump M which is essentially a reciprocal piston 76 mounted interiorly of the cylinder 78- with the rear end of the cylinder as well as the plunger rod ill projecting exteriorly of the reservoir 26. A valve unit 82 is at the discharge end of the pump 74- and basically may embrace the standard twin check valve type of arrangement which will permit the hydraulic fluid to be withdrawn within the cylinder 78 upon retraction of the piston '76 from the reservoir 26 but not permit fluid within the tube 84 from being withdrawn. Upon depression of the plunger rod and inward displacement of the piston 76, this check valve arrangement will prevent the hydraulic fluid in the forward part of the cylinder from passing into the reservoir 26. It will rather be forced upwardly through the tube 84- mm the central chamber 32 of the rotor 28 and eventually, to the location illustrated in FIGURE 2 at which the base 56 of the container 52 is flexed upwardly as shown.

A tube 84 adapted to permit passage of the hydraulic fluid pumped by the pump 74 is mounted coaxially and interiorly with respect, to the motor output shaft 20 with its upper end terminating interiorly of the central chamber 32 As an exemplary application of the centrifuge and fractionating system of this invention, it may be desired to subject to centrifugal forces oxalated, human blood in order to. separate in into its constituents. Whole blood would then be put into the container. 5-2 through opening 64, hearing in mind that the container 52, under these circumstances, may be provided as a disposable unit which, if desired, may be discarded after a single use. The blood would then be spun at relatively high speeds for suflicient time by rotating the rotor 12 upon actuation of the motor 14. The blood would be observed separating. into three definite and distinct stratas, namely, redcells 86, white cells 88 and plasma 90. If sufficient hydraulic fluid 72 is now pumped up through the stationary tube 84 into the rotating chamber 32, centrifugal force will cause the emanating fluid to displace upwardly the flexible diaphragm 48 and, consequently, the base 56 to gradually assume the position shown in FIG. 2. As the diaphragm 4-8 and base 56 move upwardly, the cells 86 and 8-8 are also displaced and cause plasma 9% to overflow the opening 64 and deposit in the collection chamber 68.

If the rotor 12 is now stopped, by means of deactivation of the motor 14, hydraulic fluid 72 will flow back into the reservoir 26 through the tubular shell defined by the bore 34 and tube 84. Consequently, the diaphragm 4 8 and container base 56 will return to normal position. If a sample of the plasma is taken from the chamber 68 and microscopically examined, it will be found virtually cell-free. This is the case because the plasma was displaced and expelled by overflowing without disturbing the interface of the cells which was held by extra gravitational force. In addition, in actual practice virtually no flow of plasma 94 occurs across the face of the cell strata 88 when the plasma is expelled to the collection chamber 68.

When the plastic container 52 contains fluid and is rotated at high speed, it will expand slightly because it is not fully supported around all of its outer walls. At relatively constant r.p.m., precisely controlled amounts of liquid can be expelled over the rim opening 64 by actuating the piston plunger rod 80. However, if the speed or" the rotor 12 is substantially reduced, container 52 will contract and a small, but undesirable amount of fluid will be expelled over the rim opening 64. In order to circumvent this the operation of the spring biased Weights 42, come into play. Thus, when the rotor 12 is at rest, the weights 42 and their biasing springs 44 will be positioned substantially as shown in FIG. I. With the rotor 12 at running speed, the weights 42 will shift radially outwardly under the influence ofcentrifugal force. The springs 44, under such circumstances, will be compressed by the weights 42 which will also serve to displace a portion of the hydraulic fluid 72 out through thevertical ports 38. Now, if the rotor speed is reduced, the reduction in centrifugal force acting on weights 42 will permit the springs 44 to move the weights radially inwardly towards the axis of rotation. The immersed volume of the weights 42 in the hydraulic fluid '72 will be, as a consequence, reduced, Under these circumstances, the distance between the center axis or axis of rotation and the level of the fluid 72 in the rotor 12 will increase. Hence, the fluid at the rim opening 64 will retract and not overflow. The amount of this retraction is arranged to be greater than the contraction of the container 52 which would ordinarily cause the undesirable overflow if provisions Were provided or made to offset or compensate for this effect. It should be noted, however, that good separation can be obtained without this compensating mechanism, but not with the extreme and optimum accuracy which may be desired or required in certain clinical applications.

Referring now to FIG. 3, a receptacle 100 is shown conveniently mounted by the rotor 12 particularly for purposes of attaining continuous centrifuging and, consequently, liquid separation. This receptacle 1% is usable with other centrifuge forms as well, including that disclosed subsequently herein. The container includes a flexible plastic base 102 secured to a top 1% along a peripherally extending heat sealed zone 106. The top 104 is provided with the conical upright collar 168 defining the lip opening 110. A substantial-1y rigid post 112 is aflixed centrally to the base 102 in a suitable manner. Reniovably attached to the post 112 is a dispersion cup 114 provided with a series of circumferentially extending.

ing operation of the rotor 12 is adapted to be concentrically mounted with respect to the axis of rotation of the rotor 12. It is, therefore, in substantial coaxial relationship with respect to the container res, and thereby is in a position to collect the liquid constituents of lighter specific gravity expelled from the container chamber 120. A feed tube 124 extends through the cover 126 of the collector 122 to conduct the liquid to be separated into the chamber 120. The association between the tube 124 and collector cover 126 is a removable or detachable one in that the tube may be inserted in place and removed therefrom at the will of the centrifuge operator. In this connection, a ring 128 serves to determine the maximum degree of insertion of the tube into the central chamber 120 and ultimately into the interior of the cup 114 through the central opening 113 provided therein.

The collector 122 is fixedly mounted by means of the support 132 only partially shown in the figure. The collecbor 122 is substantially annular-1y shaped as shown and thusly is provided with the annular collection chamber 134. A discharge outlet or nozzle 136 facilitates the continuous or desirable extent of removal of the collected separated constituents of the liquid fed into the central chamber 120 through the tube 124.

Thus, if the container 11113 is spun in the rotor 1-2, liquid to be centrifuged is fed through tube 124 at a substantially controlled rate. This liquid will course into the interior of the cup 114, and eventually out through the series of opening 116. The liquid will then be directed under the disc 11% and out to the annular peripheral zone of the inner chamber 120 at which the greater centrifugal forces act. Here the heavier particles of the liquid to be separated will deposit substantially as shown at 138. The

pumping unit or its equivalent as discussed in connection with the embodiment of invention of FIG. 1. A valve 162 controlling the opening of the outlet orifice 164 for this hydraulic fluid 158 is provided with a lever 165, the valve and lever both being hinged at 163. Centrifugal force acting on the lever 1&6 will tightly hold the valve 162 in a closed position at which it seats across the aperture 164. The valve may be actuated when the rotor is turning at high speed by moving the tube 160 through suitable actuating mechanism for such purposes upwardly against the valve lever 166. Under such circumstances, the fluid 158 will be expelled into the cirouinferentially extending well 170 which is suspended from and fixed to a stationary support 172. The liquid collected in the well passes out through the conduit 174 and thence into a reservoir typified by FIG. 1. This valve mechanism permits the operator to retract liquid levels in the rotor and is an alternative to the spring biased weigh-ts discussed in connection with the embodiment of centrifuge of FIG. 1. In addition, the mechanism of FIG. 4 will facilitate the entire emptying of fluid 158 from the rotor at speed.

With respect to the types of displacement or hydraulic fluid 158 usable with this present invention, attention is initially directed to FIG. 4 at which the level of the surfaces of

liquids

154 and 158 are substantially the same. This will be correct provided the average specific gravity of the

constitutents

154, 156, and 176 are substantially equal to the liquid 158. I have found it advantageous to use displacement fluid 158 which is heavier than the liquid lighter mediums or constituents will overflow into the annular chamber 134 of the collector 122. Here the degree of separation obtained would be contingent on the rate of feed through the tube 124- as ovell as the rotor speed. After a batch of liquid has been through the apparatus one or more times, a desirable amount of filtrates 1461 will remain inthe central chamber .120. These may be precisely expelled into the collection chamber 134, after removing the tube 124, by actuating the pump 74 of the centrifuge 10, as previously desciibed. It should be understood that the support 132 can be removably attached to the machine. By this means, it can be visualized that the collector 122 could be upwardly removed, while the rotor 12 is at speed, and replaced by a fresh one. By repeating this procedure, which would include the intermediate actuating of the pump 74, an operator could collect innumerable fractions (or aliquots) from the central chamber 120. Each fraction would be taken in a clean collector to avoid cross-mixing of said fractions. In this instance, the collected fractions could be small in volume; and it has been found desirable in such cases to provide a collector that eliminates the discharge outlet 136 from the collector structure.

In FIG. 4, a further embodiment of the centrifuge as Well as container with collecting means is shown. With respect to the container 156', a removable collector 152 is disposed around the collar of the receptacle by means of a friction fit substantially as shown. This would enable an operator to separate blood, for example, into mo'fe than two fractions. In this connection, the blood would first be spun and the plasma or serum 154 would be expolled by overflowing, as heretofore described in connection with the operation of the pump 74, into the collector 152. The rotor would then be stopped, the collector 152 removed and replaced with a fresh collector. The remaining blood would then be respun and the White cells (or bulfy coiat) 1'56 overflowed into the fresh collector. By this sequence of steps, a liquid could be separated into innumerable fractions.

In the embodiments of centrifuge depicted by FIG. 4, the hydraulic displacement fluid 158 is shown disposed following pumping up through tube 16%) by means of a being centrifuged. This allows the base of any of the containers fabricated in accordance with my invention to ultimately and almost fully contact the inner surface of the container top, without tending to seal thereagainst along the annular zone 178 (see FIG. 4), prematurely.

, For medical use, fluid 158 could be glycerin which has a specific gravity of aproximately 1.26. This is greater than most body fluids. For medical or industrial uses, many heavier fluids can be used, the possible ultimate being mercury.

It will be understood that the removable and, in some instances, disposable containers contemplated by this invention provide for the convenient handling of liquids to be separated. As will be appreciated by those skilled in the art, permanent means could very readily be incorporated in the rotor for holding and expelling through displacement of the liquid to be separated. The possibilities in this regard are quite numerous and the need to expound thereon is not deemed necessary at this time.

Thus, among others, the several aforenoted objects and advantages are most effectively attained. Obviously, numerous changes in construction and rearrangements of the parts must be resorted to without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. Apparatus for separating a fluid mixture into fractions having different densities by subjecting the fluid mixture to centrifugal action comprising a rotatable driven rotor, drive means for rotating said rotor about an axis of rotation at a speed sulficient to cause the mixture to separate into fractions of different densities, a substantially circular hollow cup-shaped receptacle means having an opening on said rotor for receiving the fluid mixture to be separated, and having parts thereof flexible, centrifugally induced pressure means in the rotor including hydraulic liquid heavier than said fluid mixture for acting on said receptacle means by flexing the flexible parts thereof to reduce the capacity of the receptacle means by moving the fluid fractions centripetally out through the opening for controlled expulsion of the fluid contents therefrom, and collector means operatively associated with the receptacle means for receiving the expelled fluid.

2. The invention in accordance with claim 1 wherein said collection means is removably mounted on said receptacle.

3. The invention in accordance with claim 1 wherein said collection means is EtffiXECl to said receptacle as an integral part thereof.

4. The invention in accordance with claim 1 wherein said collection means is relatively stationary upon rotation of the receptacle and includes draining means for draining oif the separated constituents in the collection chamber.

5. The invention in accordance with claim 4 wherein feeding means are included for feeding the fluid materials into said receptacle.

6. The invention in accordance with claim 5 wherein diflusion means are located at the discharge end of the feeding means to direct the fluid materials away therefrom.

'7. The invention in accordance with claim 5 wherein the operation of the feeding means and draining means is continuous.

8. The invention in accordance with claim 1 wherein said collector means include means for permitting the introduction of additional quantities of the fluid mixture as said one of said fractions is isolated from the remainder.

9. The invention in accordance with claim 1 wherein means are provided for increasing the capacity of said receptacle means upon diminution of centrifugal forces to prevent spilling of fluid contents of the receptacle means into said collector means.

10. In combination, a receptacle for use as a linear in a centrifugation apparatus and for containing fluid materials the constituents of which are to be separated by said apparatus, the receptacle being substantially hollow and cup-shaped and having a substantially circular periphery, the receptacle including an axis and flexible wall portions distortable by said apparatus for varying the capacity of the receptacle, the receptacle including an opening spaced inwardly of said periphery from which separated constituents of the fluid materials are adapted to be expelled, a substantially tubular collection means operatively associated with said receptacle and located substantially concentrically with respect to the axis and a portion of which is radially outward of the opening, and said collection means defining a collection chamber for separated constituents of said fluid materials expelled from said receptacle upon distortion thereof.

11. The invention in accordance with claim wherein said collection means is removably mounted on said receptacle.

12. The invention in accordance with claim 19 wherein said collection means is affixed to said receptacle as an integral part thereof.

13. Apparatus for separating a fluid mixture into frac tions having different densities by subjecting the fluid mixture to centrifugal action comprising a rotor having an axis of rotation and formed with a substantially hollow cup-shaped recess concentric with the center of rotation, drive means for rotating the rotor about the axis of rotation, a liner in the recess of said rotor in the form of a substantially hollow cup-shaped body having a substantially circular periphery and having upper and lower walls spaced from each other to define a central chamher, with said upper wall being provided with an opening means spaced inwardly of said periphery and communicating with the central chamber and with said lowor wall being flexible, self-contained flexing means in the rotor for flexing said lower wall for expelling a controlled amount of the fluid contents in the central chamber out through said opening means in the upper wall, and a substantially tubular collector means located concentrically substantially with respect to the rotor axis and a portion of which is radially outwardly of the opening means in the upper wall for receiving the expelled fluid.

14. The invention in accordance with claim 13 wherein said flexing means includes a flexible boot secured in said rotor and on which the lower wall of said liner rests and further a hydraulic system for supplying hydraulic liquid to said boot to flex the boot and at the same time the lower wall to decrease the capacity of said liner.

15. The invention in accordance with claim 14 wherein means are provided for automatically increasing the capacity of said liner upon diminution of centrifugal forces to prevent spilling of the fluid contents of the liner into the collector means.

16. The invention in accordance with claim 14 wherein means are provided for selectively directing the liquid acting on the boot away therefrom while the rotor rotates.

17. The invention in accordance with claim 13 wherein said collector means is relatively stationary upon rotation of the rotor and liner and includes draining means for draining oil. the expelled fluid.

18. The invention in accordance with claim 17 wherein feeding means are included for feeding the fluid materials into said liner.

19. The invention in accordance with claim 18 wherein ditlusion means are located at the discharge end of the feeding means to direct the fluid materials away therefrom.

20. The invention in accordance with claim 18 wherein the operation of the feeding means and draining means is continuous.

References Cited by the Examiner UNITED STATES PATENTS 1,483,484 2/.1924 Rubert 233-20 2,104,162 1/1938 Macklind 233-20 2,141,025 12/1938 Strezynslri 2332O 2,542,456 2/1951 Ayres 233l9 3,179,334 4/1965 Sharples 23320 FOREIGN PATENTS 1,260,968 4/1961 France.

M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner.

Claims

1. APPARATUS FOR SEPARATING A FLUID MIXTURE INTO FRACTIONS HAVING DIFFERENT DENSITIES BY SUBJECTING THE FLUID MIXTURE TO CENTRIFUGAL ACTION COMPRISING A ROTATABLE DRIVEN ROTOR, DRIVE MEANS FOR ROTATING SAID ROTOR ABOUT AN AXIS OF ROTATION AT A SPEED SUFFICIENT TO CAUSE THE MIXTURE TO SEPARATE INTO FRACTIONS OF DIFFERENT DENSITIES, A SUBSTANTIALLY CIRCULAR HOLLOW CUP-SHAPED RECEPTACLE MEANS HAVING AN OPENING ON SAID ROTOR FOR RECEIVING THE FLUID MIXTURE TO BE SEPARATED, AND HAVING PARTS THEREOF FLEXIBLE, CENTRIFUGALLY INDUCED PRESSURE MEANS IN THE ROTOR INCLUDING HYDRAULIC LIQUID HEAVIER THAN SAID FLUID MIXTURE FOR ACTING ON SAID RECEPTACLE MEANS BY FLEXING THE FLEXIBLE PARTS THEREOF TO REDUCE THE CAPACITY OF THE RECEPTACLE MEANS BY MOVING THE FLUID FRACTIONS CENTRIPETALLY OUT THROUGH THE OPENING FOR CONTROLLED EXPULSION OF THE FLUID CONTENTS THEREFROM, AND COLLECTOR MEANS OPERATIVELY ASSOCIATED WITH THE RECEPTACLE MEANS FOR RECEIVING THE EXPELLED FLUID.