Cell washing centrifuge apparatus and system
Rohde et al.  
 [ CELL WASHING CENTRIFUGE APPARATUS AND SYSTEM [75] Inventors: Vernon C. Rohde, Newtown; Josef Blum, Norwalk, both of Conn.  
 [73] Assignee: E. 11. du Pont de Nemours and Company, Wilmington, Del.  
 [22] Filed: May 25, 1973 [21] Appl. No.: 364,150  
 [52] U.S. Cl. 233/14 R; 233/26 [51] Int. Cl. B04b 15/02 [58] Field of Search 233/1 D, 14 R, 14 A, 17,  
 [56] References Cited UNITED STATES PATENTS 1,321,288 11/1919 Dalzell 233/26 X 1,351,265 8/1920 3/14 R 3,352,486 11/1967 233/26 3,420,437 1/1969 233/26 3,561,672 2/1971 233/17 3,706,413 12/1972 233/26 3,722,789 3/1973 Kennedy 233/26 Apr. 15, 1975 3,737,251 6/1973 Berman et al. 23/259 X 3,786,919 1/1974 Deringer 233/14 R FOREIGN PATENTS OR APPLICATIONS 864,410 4/1961 United Kingdom 233/26 Primary Examiner-George H. Krizmanich [57] ABSTRACT Apparatus and system for treating biological materials by alternate centrifugation and decanting steps. Predetermined equal quantities of treatment or washing liquid are automatically introduced simultaneously into each of a plurality of rotating swinging centrifuge tubes by means of a distributor that rotates with the centrifuge. After centrifugation, the centrifuge tubes descend to a restricted vertical or near vertical position in which location decantation takes place while the centrifuge rotates at a slower decanting speed. Thereafter, the cycles of centrifugation and decantation are repeated automatically. Means are also provided for preventing contamination of wash liquids during transmission thereof to the distributor.  
 1.9 Claims, 9 Drawing Figures PATENTEBAPR 1 5 9. 5  
 SHLU 3 UP 5 PATENTEDAPR I 51.975  
 sum u o 5 1 CELL WASHING CEN TRIFUGE APPARATUS AND S TEM 3 BACKGROUND OFTHE INVENTION 1, Field Of The Inventionf The present invention relates toan apparatus and system for treating and washing biological materials and. more particularlyi to a system including means for centrifuging said materials in a plurality of swinging centrifuge tubes. a distributor which is separably connected to and rotates with the centrifuge rotor and which projects washing fluid into each of said tubes. and a metering peristaltic pump which transmits a predetermined quantity of washing fluid to the rotating distributor.  
 2. Description Of The Prior Art In Blum et al.. U.S. Pat. No. 3,420,437. a cell washing centrifuge is disclosed in which a swinging tube centrifuge rotor provides for alternate centrifugation and decantation of materials without removal of the rotor from the apparatus. In that system. it is necessary to remove the cover&#39;of the apparatus to insert fresh wash liquid into each of the test tubes before the next procedure of centrifugation and decantation takes place.  
  Blum US. Pat. No. 3.706.413, discloses automatic means for filling the centrifuge tubes with wash liquid. including a system for transmitting said wash fluid by a piston pump to a stationary distributor spaced apart and independent from the centrifuge rotor. A second piston pump was provided for producing air stream jets to purge residues of liquid from the nozzles of the distributor and project them into the respective centrifuge tubes. In this apparatus. it was necessary to transmit the wash fluid through a piston pump which introduced possibilities of contamination of sterile wash liquids necessary in the treatment process. Furthermore. indexing means were necessary to locate the centrifuge tubes precisely opposite the respective stationary distributor nozzles when the tube filling step took place.  
  Other prior centrifuging systems are disclosed in the reference patents cited in U.S. Pat. Nos. 3.420.437 and 3.706.413.  
 SUMMARY OF THE INVENTION In order to improve upon the apparatus and systems shown in the prior art. the present invention obviates some of the drawbacks and disadvantages thereof by providing a distributor releaseably connected to the rotor of a swinging tube centrifuge. said distributor rotating with said rotor and projecting wash fluid into each of said tubes during rotation of the rotor. Furthermore. the distributor is supplied with metered amounts of wash fluid by means of a peristaltic pump. or the like. which transmits sterile or other biologically clean fluids without subjecting the latter to any possible contamination that would otherwise be incurred when passing such fluids through the interior of a pumping mechanism. The peristaltic pump produces impulses externally upon a flexible tube made of vinyl or the like through which the fluid passes directly from the storage reservoir to the centrifuge distributor.  
  Since the distributor rotates with the centrifuge rotor during the tube filling action. the requirements for indexing means is obviated and centrifugal force takes care of purging the distributor nozzles of residual droplets of wash liquid which are automatically discharged into the respective centrifuge tubes.  
  According to the improved system and apparatus herein. the cell washing process takes place automatically through the successive steps of tube filling. centrifugation and decantation from beginning to end without contamination or handling of wash fluids and without the necessity of performing repeated manual operations to flll and refill the swinging tubes of the centrifuge rotor.  
  These and other novel features and advantages of the present invention will be described and defined in the following specification and claims.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically represents the cell washing system of the apparatus herein, including a fragmentary portion of the reservoir. a front elevation of the peristaltic pump, and a side elevation of the contrifuge and decanting apparatus. part of the latter being broken away to show a portion of the interior thereof in elevation;  
  FIG. 2 is a vertical central section view of the upper portion of the centrifuge apparatus shown in FIG. I. some parts being shown in elevation and some parts in dotted outline;  
  FIG. 3 is an exploded partial view. in elevation. of a portion of the apparatus shown in FIG. 2, some parts being omitted and some parts being shown in section:  
  FIG. 4 is a top view taken on line 44 of FIG. 3., some parts being omitted and some parts being broken away;  
  FIG. 5 is a bottom view taken on line 5-5 of FIG. 3, some parts being broken away;  
  FIG. 6 is a greatly enlarged top view ofthe distributor shown in FIGS. 3 and 5, some parts being broken away and some parts being shown in dotted outline;  
 FIG. 7 is a section view taken on line 77 of FIG. 6:  
  FIG. 8 is a somewhat enlarged perspective view of a portion of the peristaltic pump shown in FIG. I; and  
  FIG. 9 is a diagrammatic representation of the control circuit for the apparatus and system herein.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is shown in FIG. 1 a schematic representation of the improved cell washing system herein including an automatic cell washing apparatus. generally designated 11, which has a base section 12 mounted on suitable feet 13 that rest upon a laboratory table or the like.  
  Base 12 contains an electric centrifuge motor 14 and electrical circuitry operated by a suitable control knob 15. Supported on base 12 is a generally circular, bowl shaped centrifuge container 16 to which is connected. by means of hinge I7, a circular closure cover comprising an annular wall 18 and a cover plate 19 integrally formed therewith. Said cover is releaseably secured in position by a suitable lock element 20. Located within container 16 and cover I8 is a centrifuge apparatus which will be described in greater detail hereinafter. Mounted on the central top portion of cover 18 is an angled tubular fixture 21.  
  The system herein includes a wash water supply reservoir 22 connected by way of flexible tube 23 to fixture 21 on the centrifuge. Located between reservoir 22 and centrifuge apparatus 11 is a peristaltic pump 24 operated by an electric motor 25. An intermediate portion of tube 23 extends around a rotatable capstan 26 of peristaltic pump 24 (FIG. 8) whereby the spaced rollers 27 of said capstan produces successive peristaltic pinches on tube 23 in order to cause the wash fluid to flow therethrough to the centrifuge apparatus. A suitable variable restrictor valve 28 may be incorporated into that portion of tube 23 extending between reservoir 22 and pump 24 for predetermining or controlling the quantity of fluid that passes from the reservoir to the centrifuge.  
  The centrifuge apparatus for rotating a plurality of swinging test tubes is similar to that shown in Blum et a]. US. Pat. No. 3.420.437 (issued Jan. 7. 1969). which discloses detailed structures for controlling the positioning of the tubes during the respective centrifuging and decanting operations. It is to be assumed that such control structures or suitable modifications thereof are also utilized in the present apparatus.  
  Extending through and rotating freely through a suitable aperture 31 in the bottom of container 16 is a drive shaft 32 connected to and rotated by electric motor 14 is base section 12. See FIGS. 2 and 4.  
  Mounted on shaft 32 and rotatable therewith is a circular centrifuge bowl 33. Secured to the central interior portion of said bowl. and rotating therewith. is a circular base element 34. Extending through and upwardly from base 34 and located axially relative to drive shaft 32 is a spindle 36 which is rotatably driven by shaft 32. Removably mounted over and rotated by spindle 36 is a tubular hub 37 to the upper end of which is axially connected horizontal carrier plate 38 extending outwardly from said hub. Arrayed in a circle coaxially with hub 37 near the outer portion of plate 38 is a plurality of evenly spaced apart slots 39, each of which is pivotally engaged by the curved hinge 41 of a skeleton tube carrier. generally designated 42, integrally formed with said hinge. Each tube carrier 42 comprises an elongated spine having one or more spaced apart integrally formed circular tube bands or rings 43. The bottom portion of tube carrier 42 terminates in an outwardly curved supported flange 44. Each swinging tube carrier accommodates an elongated centrifuge tube 46.  
  When the centrifuge is at rest or in the decanting position. tube carriers 42 and tubes 46 are positioned in a vertical or near vertical position. When the apparatus is in the centrifuging condition. tube carriers 42 and tubes 46 swing outwardly. as shown in FIG. 2, where they are retained at the angled position by virtue of the outward ends of flanges 44 bearing by centrifugal action against the inner wall of bowl 33. It is understood that the various suitable mechanisms for releaseably locking the tube carriers 42 in the decanting position. as disclosed in US. Pat. No. 3.420.437. or mechanisms similar thereto. will be utilized in the apparatus described herein.  
  Secured to the upper interior end of tubular hub 37 is a stub 47. the upper end of which terminates in a knob 48 extending upwardly above carrier plate 38. Knob 48 has upper and lower inwardly beveled annular surfaces 49 and 51, respectively. the function of which will be described hereinafter.  
  An annular collector trough 56, located within annular closure wall 18, has an integrally formed annular flange 57 which is secured to a peripheral portion of the bottom surface of cover plate 19. See FIG. 2. The bottom of collector 56 has an integrally formed. inwardly extending annular shelf 58, the inner circular edge of which is located in a position where decanting liquids are received from centrifuge tubes 46 when the latter are rotated in the vertical or near vertical position. In one location of shelf 58, at a juncture with the vertical portion of collector trough 56, there is a drain outlet 59 to which is connected one end of flexible drain tube 61 which extends through a suitable aperture in annular wall 18. The other end of tube 61 (not shown) is located in a suitable place for collecting or disposinng of the decanted materials.  
  Secured to the inner central top portion of cover plate 19 is the central base portion 62 of a downwardly and outwardly extending annular baffle 63. The vertical portion of tubular fixture 21 is secured to cover plate 19 by means of a circular shield 64 which closes the central apertures in cover plate 19 and in base portion 62, respectively. The lower end of fixture 21 has an integrally formed port element nozzle 66 which extends a short distance below the inner surface of base portion 62 into the interior of the centrifuge apparatus.  
  The distributor, generally designated 70. comprises an assembly of two releaseably connected elements. namely, a circular nozzle holder 71 and a closure cover 72. secured to the nozzle holder by means of spaced screws 73. See FIGS. 2, 4, 5, 6 and 7. The bottom portion of nozzle holder 71 has a central circular recess 74 bounded on two sides by elongated arcuate niches 75 spaced l apart. Located in circular array on the peripheral bottom portion of cover 72 are integrally formed. downwardly extending spaced legs 76 that define a plurality of alignment recesses. the function of which will be described hereinafter. Secured fast by means of a screw 77 on the inner end of recess 74 is the base of a spring element 78 having integrally formed. downwardly extending. inwardly biased bowed spring wings 79. When distributor 70 is assembled into the apparatus. it is pressed downwardly over knob 48 whose beveled surface 49 urges wings 79 apart. Wings 79 then ride over the wide portion of said knob and engage beveled surface 51 to secure the distributor assembly 70 to the knob. Niches 75 provide room for the flexing action of wings 79 which are aligned therewith. Carrier plate 38 has a plurality of sockets 81 in spaced circular array which accommodate correspondingly arrayed downwardly descending pins 82 mounted in the bottom surface of nozzle holder 71 in order to cause said distributor to rotate in unison with the centrifuge.  
  Nozzle holder 71 has a plurality of radially extending spaced channels 83 oriented downwardly and outwardly from the top center of said holder. Located in the outer portion of channels 83 are. respective tubular nozzles 84, the outer ends of which extend outwardly and in radial array toward corresponding centrifuge tubes 46. Access to the inner ends of channels 83 is provided by a central aperture in cover 72 into and through which wash fluid is transmitted from nozzle 66.  
  The outer end of each nozzle 84 may be cut at an angle relative to the axis thereof so that fluid emerging therefrom may be prevented from spraying upwardly. The wash fluid being delivered to the well formed by aperture 85 and the top apex dome 86 of holder 71 is caused by the rotation of holder 71 at centrifugal speed to expel said fluid in jet streams through nozzles 84 into the respective centrifuge tubes 46. By suitable equidistant spacing of channels 83 in relation to the symmetrically shaped conical dome 86, the distribution of substantially equal amounts of fluid into tubes 46 is ensured.  
  By virtue of the engagement of pins 82 with corresponding apertures 81 in carrier plate 38. nozzles 84 are always properly aligned with respective tubes 46.  
  The electrical schematic drawing of FIG. 9 represents on embodiment of typical control system for operating the automatic cell washing apparatus herein. The centrifuge motor to which shaft 32 is connected is operated by its timer. controlled by knob 15. The peristaltic pump motor is controlled by its separate timer operated by a second knob. not shown. Both control knobs are mounted on the sloping front panel of base section 12. After the biological specimens have been inserted into each of the centrifuge tubes 46. the centrifuge motor 14 is started to cause rotation of carrier plate 38 whereby tubes 46 swing outwardly to the angled centrifuging position as shown in FIG. 2. The centrifuge timer is adjusted to determine the duration of centrifugation.  
  When tubes 46 have reached the angled centrifuging position. a signal in the electrical control system actuates a solenoid selector switch to cause operation of peristaltic pump 24 by pump motor 25 whereupon a predetermined quantity of fluid is transmitted from reservoir 22 through tube 23 into the well of distributor 70 whence the wash liquid is projected centrifugally through nozzles 84 into respective tubes 46 in a quantity predetermined by the timer connected to the pump motor and. additionally. by the adjustment of restrictor valve 28. The setting on the pump motor timer may be determined and calibrated so that the operator can set the on time ofthe pump motor for a requisite period for filling the centrifuge tubes 46 with the proper amount of wash liquid.  
  After wash liquid has been introduced into the spinning centrifuge tubes 46. centrifugation is continued for the necessary time as may be empirically determined by experimentation and the like. the timing of this function being set by the timer connected to centrifuge motor 14.  
  After centrifugation is completed. the centrifuge timer automatically stops the rotation of the centrifuge to permit test tubes 46 to descend to their suspended position where they are all automatically secured in a vertical or near vertical decanting position as shown by the dotted outlines in FIG. 2, and retained there by means described. for example. in U.S. Pat. No. 3.420.437. or by any other suitable means. Thereafter. the timer again activates the centrifuge motor 14 to cause rotation of test tubes 46 in the vertical or near vertical position at a slower speed for a predetermined period whereby decantation of the supernatant fluid takes place from said tubes onto shelf 58 whence said fluid descends by gravity through drain outlet 59 and drain tube 61 to a suitable reservoir or sink. The foregoing steps define a single cell-washing cycle.  
  it is to be understood that when the centrifuge tubes are described and claimed herein as being in the vertical decanting mode. the word &#34;vertical&#34; is intended to include the concept of near vertical since in various embodiments of the apparatus it may be desirable. when the apparatus is in the decanting mode. to have the tubes positioned in slightly outwardly or inwardly inclined positions relative to the true vertical as distinguished from the widely angled position of said tubes in the centrifuging mode. These alternative possibilities are disclosed in Blum et al.. U.S. Pat. No. 3.420.437.  
  After the predetermined decantation cycle takes place. as controlled by the centrifuge motor timer. the tube restraining mechanism (not shown) on the centrifuge automatically releases the holders 42 of tubes 46. after which the centrifuge motor is started again in the centrifugation mode to cause said tubes to assume the angled centrifuging position as shown in FIG. 2. At that time. the pump motor 25 becomes automatically activated to cause peristaltic pump 24 to draw fresh saline solution from reservoir 22 and transmit it through tube 23 and fixture 21 into the well formed by the aperture 85. During this fill cycle. the centrifuge rotor rotates at approximately 1.200 rpm. while centrifugal force propels the saline solution through nozzles 84 into the respective centrifuge tubes 46. By virtue of the geometry of the distributor and the rotor. nozzles 84 project slightly into the upper open ends of tubes 46 which are spinning and are maintained at an angle of approximately 42 from the vertical. in one embodiment of the apparatus. From the time the saline solution enters the distributor to the time it impinges upon the previously centrfigued residuum or button in each tube 46 and is accelerated by increasing centrifugal force. the velocity of the fluid being projected into the respective tubes 46 resuspends the residual materials therein and accomplishes the washing action that is intended by the apparatus.  
  After the predetermined metered quantity of saline solution has been centrifugally projected in the centrifuge tubes 46, pump motor 25 is stopped by its respective timer after which further centrifugation is continued by centrifuge motor 14 until the requisite predetermined time has elapsed in accordance with the setting of the centrifuge motor timer. Thereafter. the tube filling. cell washing centrifugation. and decanting cycles may be repeated as required by clinical or experimental considerations. A suitable wash cycle selector may be included in the control circuit for the-apparatus herein in order to permit the operator thereof to select the number of complete tube filling. centrifuging. and decantation cycles to be performed.  
  The cell washing apparatus disclosed herein provides a virtually closed system from the saline reservoir 22 to the drain aperture 59 whereby possible contamination and erroneous results are minimized oreliminated. By providing the unitary tube 23 which transmits saline from reservoir 22 to the aperture well 85 in distributor 70, the integrity of that solution is preserved. contrary to the necessity in other types of apparatus to pass through the interior of pump cylinders and the like. Tube 23 encircles rotating capstan 26 and the pumping action is impressed upon the exterior of tube 23 by an array of three or more spaced rollers 27 that peristaltically pinch said tube to cause the movement of fluid therein.  
  The requisite amount of solution to be transmitted to centrifuge tubes 46 is empirically determined before the apparatus performs actual operating experiments. and this is accomplished by adjusting the flow control or restrictor valve 28 to calibrate the delivery volume of peristaltic pump 24. Flow control valve 28 is in line&#34; in tube 23 and it may be adjusted to accommodate the operation of the apparatus to the type of material of which tube 23 is made and to its internal diameter which determines its flow capacity.  
  Should any contamination occur in the sale wash solution in reservoir 22 or in tube 23, all that is necessary is to replace or re-sterilize said tube and reservoir 22. and distributor 70.  
  By virtue of the fact that distributor nozzles 84 are rotating at high speed during the transmission of washing fluid into centrifuge tubes 46. centrifugal force will automatically purge said tubes of any residual wash liquid so that no auxiliary purge devices and equipment are required to clear said tubes of the wash liquid.  
  Since the distributor is attached to and rotates with the centrifuge rotor. there is no problem of causing the rotor to come to rest in any one of several discrete locations for alignment of the centrifuge tubes with stationary jet nozzles as was required in some prior art devices. Furthermore. there is no requirement in the present apparatus to provide any high pressure delivery of wash fluid as is requisite in a stationary fluid-filling apparatus since, inthe present apparatus. centrifugal force causes the wash fluid delivered from nozzles 84 to be projected with sufficient pressure into tubes 46 to cause the materials therein to be resuspended.  
  It will be noted that when the centrifuge tubes 46 are in the angled centrifuging position as illustrated in solid lines in FIG. 2. the top portions of said tubes are located within respective recesses between legs 76 whereby accidental skewing of said tubes on their respcctive hinges 41 is prevented. thus ensuring that liquids from nozzles 84 will be directed into the respective centrifuge tubes.  
  Furthermore. in order to ensure a liquid-tight seal between holder 71 and closure cover 72. there may be provided a resilient 0-ring 87 therebetween. made of a suitable material such as nylon. Teflon. rubber. or the like.  
  Although the present invention has been described with reference to particular embodiments and examples. it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention. The Abstract given above is for the convenience of technical searchers and is not to be used for interpreting the scope of the invention or claims.  
 We claim:  
  l. A system for treating biological materials and the like. comprising: a swinging tube centrifuge having a rotor. a plurality of swinging tube holders mounted on said rotor for holding centrifuge tubes. and a variable speed drive for said rotor; a distributor mounted on and rotating with said centrifuge. said distributor having a plurality of spaced. radially extending nozzles equal in number to said tube holders. said nozzles being aligned with but unconnected to said tube holders. said tube holders being pivotally mounted on said rotor so that the mouth ofthe centrifuge tubes held by said swinging tube holders is brought into close proximity with said nozzles when said rotor is in high speed rotation; a source of treatment fluid; tube means connected between said source and said distributor for transmitting said fluid to said distributor; and pulsing pump means operating upon an cxterior portion of said tube means for urging said fluid from said source to said distributor.  
  2. The system according to claim 1. and further comprising valve control means between said source and said pump for adjusting and controlling the flow of said fluid between said source and said distributor.  
  3. The system according to claim I wherein said pump means comprises a peristaltic pump.  
  4. The system according to claim 1 wherein said distributor is removably mounted on said centrifuge and wherein said system further comprises cooperating indexing means on said distributor and on said centrifuge for locatingsaid nozzles opposite respective tubes.  
  5. The system according to claim&#39;4 wherein said nozzles are arrayed outwardly and downwardly at an angle and wherein said tubes in the centrifuging position are at an angle for receiving fluid directly from said nozzles.  
  6. The system according to claim 1 wherein said drive is a two-speed drive for said centrifuge. said tubes assuming an outwardlyextended array in the high speed mode of said drive. said tubes assuming a vertical decanting position in the low speed mode ofsaid drive and said-nozzles projecting fluid into respective tubes only when the latter are in the centrifuging mode.  
  7. The system according to claim 6 and further comprising an annular trough surrounding said centrifuge. said trough receiving liquid materials from said tubes when the latter arein the vertical decanting mode.  
  8. The system according to claim 1 wherein said drive is a two-speed drive and said tubes are maintained in a vertical or near vertical position for decanting liquids from said tubes at low speed drive. i  
  9. The system according to claim 8 wherein said pump means is operative only when said tubes are in the centrifuging mode to cause equal amounts of fluid to be projected by centrifugal force through said nozzles into respective tubes.  
  10. The system according to claim 9 and further comprising electrical circuitry for operating said two-speed drive and said pump means. and timing means in said electrical circuitry for determining the sequence and timing of filling the tubes with treatment fluid. and operating said drive at centrifuging and decanting speeds.  
  11. The system for treating biological materials and the like. comprising a swinging tube centrifuge. a multispeed motor for rotating said centrifuge at a predetermined centrifuging speed. and alternately at a lower decanting speed. a source of treatment fluid. means for transmitting said fluid to said centrifuge. pulsing pump means operating on said transmitting means for urging said fluid from said source to said centrifuge. a pump motor for said pump. electrical circuit means connected between said centrifuge motor and said pump motor for causing said centrifuge motor to operate alternately for the respective centrifuging and decanting modes of said centrifuge. and for causing said pump motor to operate to transmit treatment fluid to said centrifuge driving the centrifuging mode.  
  12. The system according to claim ll and further comprising control means in said electrical circuit for predetermining the timing and sequence of each of the tube filling. centrifuging and decanting modes of the system.  
  13. The system according to claim 12 and further comprising means in said electrical circuit for causing the system to repeat for a predetermined number of cycles the successive tube filling. centrifuging and decanting modes of the apparatus.  
  14. The system for treating biological materials and the like. comprising a swinging tube centrifuge. a plurality of swinging tubes in circular array on said centrifuge. a source of treatment fluid. a distributor removably mounted on and rotating with said centrifuge for projecting treatment fluid into respective centrifuge tubes. said distributor comprising a plurality of spaced radially extending nozzles equal in number .to said swinging tubes. said nozzles being aligned with but unconnected to said swinging tubes. means for alternately rotating said centrifuge at a centrifuging speed and at a lower decanting speed. means for transmitting a metered quantity of treatmentfluid into and through said distributor and into said centrifuge tubes during the centrifuge mode of the centrifuge. said centriguge tubes being pivotally mounted to swing into close proximity with said nozzles during the centrifuging mode.  
  15. The system according to claim 14 and further comprising timing means connected between said rotating means and said fluid transmitting means to control and selectively predetermine the operational times of the separate and successive tube filling. centrifuging. and decanting functions of said system.  
  16. The system according to claim 14 wherein said fluid transmitting means comprises a peristaltic pump connected between said sourceand said centrifuge.  
  17. The system according to claim 16 and further comprising a restrictor valve connected in said fluid transmitting means between said source and said peristaltic pump.  
  18. The system according to claim 14 wherein said fluid transmitting means comprises a closed system between said source and said distributor.  
  19. The system according to claim 14 wherein said fluid transmitting means comprises a flexible tube connected between said source and said distributor and a peristaltic pump operative upon the exterior portion of said tube to cause the movement of said fluid from said source to said distributor.