US1997935A - Method of and apparatus for agitating mixtures - Google Patents

Description

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'3 persons with different degrees of thoroughness the minor axis thereof, whereby emcient agitaf o Patented Apr. 16, 1935 Q 'UNITED STATES PATENT FFICE METHOD OF AND APPARATUS FOR AGITATING MIXTURES Silvie Lloyd Johnson, Catonsville, Md.

7 Application November 15, 1934, Serial No. 753,207 I 10 Claims. (01. 25957) This invention relates to methods of and appa- Figure 4 is a fragmentary view in rear elevation ratus for agitating mixtureamore particularly of a tube-supporting spider.

mixtures of blood and diluents, as, for example, In accordance with my improved method, the

mixtures formed in the preparation of blood b ood sample and diluent are p ac d in a Suitable 5 specimens for microscopic examination. Al- Vessel, Preferably a P p tube formed With though th th and apparatus in accordance bulb, and the tube is moved in an orbital circular with my invention may be used for the agitation path about a substantially horizontal axis at a of the i t thgy were developed t peradial distance from the axis and at a rotative i l regard to the requirements of such tu speed so mutually related that the constltuentsof 10 f blood and diluents and the invention as the mixture will move back and forth in the bulb 10 1 f h and will not be held in the outermost confines of gag Wm be described for t V the bulb by centrifugal force. It W111 be appre- In the preparation of blood Samples for 3119413 ciated that, if the relation between the radial .dis- 'sis'or study the usual procedure is to place a tance of the vessel Irom the axis of rotation and measured quantity ofthe blood in a pipette tube the speed of rotatlfm are so mljltuauy related h formed. with a capillary opening and with an enconsldqmble centnfugal force i w a largement or bulb intermediate the ends of the We W111 be thrcwn out aemtihewrrmPSt opening, and to dilute the sample'in the tube with W of P t? that E ofithem a measured quantity of suitable'fiuid, the amount herough mtermlxl'ng of M16 onstituents and 1 a form suspensionof blood corpuscles the co and nature of the diluent depending upon the um r L kind of study to be made. The mixture thus latter Wm be thrown 130 outelmost eonfinesgf i Y the bulb and will be segregated from the fluid i r forged f i m ig eqect E1101 constituents. Ittherefore is important that the .gg g fg g gg :2? ggi gg i radial distance of the-bulb from the axis of rotaf Sp y tion and the speed of rotation be so related that 2:: throughout the mixture in suspenslon. Her-etc- 7 no substantial centrifugal force is exerted. In fore the agitation has been eficcted by manual Shaking of the pipette tubes and, if the manual accordance with aturther feature of my improved u are obtained WT 1t 15 utmmfnmon so that the major axes of the bulbs are disposed -30 tor the thoroughness of the manual agitation to atanvoblique angle to the axiq of rotation Whe-n if P and fact tubes thus disposed areirotated at a low speed, cia'bly dii-f-erent results have been observed in the fluid mixture contained in the bulbs Wm making mlmlyses {of the m 9 t slosh around in the bulb, moving both in the disamples of WhlCh' were prepa by 'dlfierent rection of the major .axis and in the direction of o i g .tion and thorough :mixing are effected. I may obJeot myfmveliltlon mf also employ the usual bead in the pipette tube method of end-Weeding fgrraigltatmg mlxtures bulb which tumbles around and assists in the I of' bloo'd andidiluentiinsuch manner as to assure formation of afun'iform mixture -40 uniform and thorough mixing. A further object The amount of b hm force tending to 40 is to provide :such :amethod andapparatus-as-are throw the fluid mixture outwardly d dslu capable of effecting the desired uniform and the acceleration f the mixture inwardly toward thomughlmlxmgiieale'sser time than heretpfore the axis of rotation. and this acceleration is sexhas :been required. Other objects will-becomeappressed by the formula: I parent from the following detailed description, p

the appended :claims, and the accompanying a=41r2n213 drawing, vin which: where a is the acceleration in inches per second Figure l is :a perspective view of an-apparatus per e d, i the revolutions .per second, and r embodying t ve t V is the radial distance of the mixture from the fi 2 a View the appa s Shown i axis of rotation in inches. Through experiments I Figure p y in elevation p -y in verbiand tests in the preparation of actual samples calsection,and dwW fi efi d subsequently subjected to microscopic studies, I Figure 3 is a View in elevation of a pipette v13111136 have ascertained that best results are obtained :and an elastic band associated therewith and when theval'ue ofthe acceleration a is about one 555 showniinsectiomiand 'hundred'inchesper secondper second. When the radial distance from the axis of rotation and the rotative speed are so mutually related that the acceleration has approximately this value, the fluid is not flung outwardly against the outer walls of the bulb, but is permitted to slosh back and forth under the combined action of the rotative movement and gravity.

One suitable form of apparatus capable of effecting agitation in accordance with the invention is shown in the drawing as including a standard A comprising a base i and an upright portion 2, and a motor B mounted on the standard by means of posts 3 and provided with the usual cord 4 housing electrical conductors. The motor shaft 5 is provided with a pinion 6 meshing with a gear l which has secured to it a pinion 8 which meshes with a gear 9 secured to a driven shaft 49.

A spider or tube support C having a hub ll formed with a square opening l2 fitting over-a square portion l3 on the shaft it: is secured in position on the shaft by means of a wing nut i4 and a washer 55 disposed between the wing nut and the hub Ii. The spider C is provided with a plurality of arms i6 which are formed at their outer ends with loops l1, each loop being pro vided with an opening I8 and a second opening I!) spaced from the opening [8. Each opening [9 is formed as a bayonet slot having a smaller opening portion Ill and a larger opening portion [9 The pairs of openings l8 and iii serve conjointly to form seats for receiving pipette tubes D, E, F, and G which are formed respectively with oval bulbs or mixing vessels D E F and G and preferably tumbling beads D E F, and G are located respectively in the bulbs D E F and G The pipettes are open on both ends, and in order to close the ends of the tubes during agitation I prefer to employ rubber or other elastic bands D E F and G passing respectively over the opposite ends of the tubes D, E, F, and G and alongside the latter.

After the blood sample and diluent have been placed in the tubes and the elastic bands applied to the latter, the tubes with the bands thereon are inserted through the larger opening portions of the bayonet slots I9 and are projected through the openings I8 until the bulbs are disposed within the loops I! and between the openings I8 and 19. The tubes are then moved from the larger openings IS of the bayonet slots into the smaller openings I9 thereof, and are held in this position by means of the rubber bands which serve to cushion the tubes in their seats and to adapt the seats for tubes of different sizes, it being understood that the tubes may vary in size depending upon the nature of the examination to be made.

Tests have indicated that more thorough mixing of the blood and diluent can be eifected in "a shorter time when the tubes are disposed at an oblique angle to the axis of the shaft H! because this arrangement results in movement of the mixture in at least two directions, i. e., in the direction of the major axes of the bulbs and also in the direction of the minor axes thereof. Although the exact amount of angularity is not critical, I have found that substantially better results .are obtained when the angle a between the shaft axis and the axes of the tub-es is from forty-five to sixty-five degrees, and preferably the angle should be about fifty-five degrees.

As previously stated, it is important that the mixture be not thrown outwardly appreciably by centrifugal force. With the bulbs of the pipette tubes disposed at a given distance from the axis of rotation, the tendency to throw the mixture outwardly will depend upon the rotative speed, and, conversely, for any particular rotative speed this tendency will depend upon the radial dis tance of the bulbs from the axis of rotation. Thus these two factors may be varied somewhat within practical limits, but their mutual relation should be such that no substantial centrifugal force is produced, and as a rough measure the relation should be such that the acceleration of the mixing vessels toward the axis of rotation is about one hundred inches per second per second. In the embodiment shown in the drawing, and as actually constructed and used in practice, the radial distance of the bulbs from the axis of rotation has been between two and a half and two and three-quarters inches, depending upon the seating of the tubes in their seats, which may vary to some extent owing to the flexibility of the seating arrangement. With the bulbs disposed at this distance from the axis of rotation, a rotative speed of one revolution per second has been found to produce the best results, and with this mutual relation between the radial distance from the axis of rotation and the rotative speed the acceleration is approximately one hundred inches per second per second.

It will be understood that within practical limits any number of arms may be provided on the spider C for carrying tubes, so that a large number of samples may be prepared for examination at the same time. The embodiment of the invention disclosed herein has been found to operate efficiently and to obtain the desired results, but it will be understood that various changes may be made in the specific construction and relative arrangement of the parts without departing from the invention as defined in the claims.

I claim:

1. The method of agitating mixtures to form suspensions which comprises moving a vessel containing the constituents of the mixture in a circular path about a substantially horizontal axis and at a radial distance and rotative speed so mutually related that the acceleration of the constituents towards said axis is approximately one hundred inches per second per second.

2. The method of agitating mixtures to form suspensions which comprises moving an oval vessel containing the constituents about a substantially horizontal axis'with the major axis of said vessel inclined to said substantially horizontal axis at an angle of from forty-five degrees to sixty-five degrees and at a radial distance and rotative speed so mutually related that the acceleration of the constituents towards said axis is approximately one hundred inches per second per second.

3. The method of agitating mixtures to form suspensions which comprises moving an oval vessel containing the constituents about a substantially horizontal axis with the major axis of said vessel inclined to said substantially horizontal axis at an angle of from forty-five degrees to sixty-five degrees and at a radial distance and rotative speed so mutually related that the constituents will move in said vessel both in the direction of the major axis and in the direction of the minor axis, and will not be held in the outermost confines of the vessel by centrifugal force.

4. The method of agitating mixtures of blood and diluent which comprises moving an oval vessel containing the constituents about a substantially horizontal axis with the major axis of said vessel inclined to saidsubstantially horizontal axis at an angle of from forty-five degrees to sixty-five degrees and at a radial distance and rotative speed so mutually related that the constituents will move in said vessel both in the direction of the major axis and in the direction of the minor axis, and will not be held in the outermost confines of the vessel by centrifugal force.

5. Apparatus for agitating mixtures to form suspensions comprising a substantially horizontal rotatable shaft; a support fixed to said shaft; a pipette vessel for containing the ingredients of said mixture and being mounted on said support and spaced from the axis of said shaft with its major axis inclined with respect to said shaft; and means for rotating said support and said vessel about the axis of said shaft.

6. Apparatus for agitating mixtures to form suspensions comprising a substantially horizontal rotatable shaft; an arm secured to said shaft; a pipette tube formed with a bulb and supported on said arm at an angle of from forty-five degrees to sixty-five degrees with respect to said shaft, the bulb being spaced to one side of said shaft; and means for rotating said shaft.

7. Apparatus for agitating mixtures to form suspensions comprising a substantially horizontal rotatable shaft; an arm secured to said shaft; a pipette tube formed with a bulb and supported on said arm at an oblique angle with respect to said shaft, the bulb being spaced from the axis of the shaft; a tumbler bead in said bulb; and means for rotating said shaft.

8. In apparatus for agitating mixtures to form I suspensions, the combination of a shaft; an arm carried by said shaft and formed with a tubereceiving seat; a pipette tube in said seat; and an elastic band passing over both ends of the tube and extending alongside of the tube and between the latter and said seat.

9. In apparatus for agitating mixtures to form suspensions, the combination of a shaft; means carried by said shaft provided with a plurality of tube-receiving seats adapted to receive pipette tubes of varying sizes within limits; a tube in one of said seats and being open at at least one of its ends; and an elastic band stretched over the ends of said tube and extending alongside of the tube between and in engagement with the latter and said seat whereby to close'the open end of said tube and also to adapt the seat to the size of the tube.

10. In apparatus for agitating mixtures to form suspensions, the combination of a pipette tube having a bulb intermediate its ends; and a rotary support for said tube, said support being provided with two spaced openings, both of which are large enough to embrace said tube and one of which is formed as a bayonet slot, the larger opening of which is large enough to permit passage of said bulb.

S. LLOYD JOHNSON.

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