US3620134A - Material transport system - Google Patents

Abstract

THIS INVENTION PROVIDES A POSITIVE DISPLACEMENT APPARATUS THAT ALLOWS ONE TO REPEAT AUTOMATICALLY IN A PRECISE MANNER THE ELUTING OR TRANSPORTING OF MATERIAL FROM A RESERVOIR, SUCH AS A COLUMN, TO A SECOND COLUMN OR A SECOND RESERVOIR. A MOTOR IS DRIVEN, UNDER CONTROLLED SPEED, TO DRIVE A PISTON INTO THE FIRST RESERVOIR AT A PRECISE RATE. AS THE PISTON ENTERS THE RESERVOIR, MATERIAL THEREIN, SUCH AS A LIQUID, IS FORCED UPWARDLY THROUGH AN APERTURE IN THE PISTON WHICH CO-ACTS WITH A TUBULAR ELEMENT CONNECTED TO THE SECOND RESERVOIR. PREFERABLY, THE BOTTOM OF THE PISTON IS CONCAVE AND THE PASSAGEWAY THROUGH THE PISTON HEAD BEGINS AT THE APEX OF THE CONCAVITY.

Description

NOV. 16, 1971 R CONLON ETAL 3,62@,H

MATERIAL TRANSPORT SYSTEM Filed Sept. 30, 1968 2 Sheets-Sheet 1 Motor M0 wr Speed $peed Conb'ol I @mdrol, 12

INVENTORS RaIplLDCcmIm, WilliamMlFLmIsIwr A TTORWEY NOV. 16, 1971 CONLQN ETAL 3,62U,fl3$

MATERIAL TRANSPORT SYSTEM Filed Sept. 30, 1968 2 Sheets-Sheet 2 F .3, AA 1 1 P f a /y v sob/m2 Solvent a g Composiliorz HTPOS IL 0 Solved 1 Time orMillililers' Time OI'MillLlikm y. l r- '5. [v y 7 H Solveub Solveni Solvent Composition ZP/eJtt Sou/emf 1 Composition,

Sela/anti M Time orMillilifiers Time orMilliliiers mvmmns PhD-@0n10n WilliamMi'Yleishcr ATTORNEY United States Patent 3,620,134 MATERIAL TRANSPORT SYSTEM Ralph D. Coulon, Wilmington, and William M. Fleisher IV, Harmony Hills, Newark, Del., assignors to Nester & Faust Manufacturing Corp., Newark, Del.

Filed Sept. 30, 1968, Ser. No. 763,632 Int. Cl. F15b 21/04; B67d /46; G011? 11/02 US. C]. 9279 3 Claims ABSTRACT OF THE DISCLOSURE This invention provides a positive displacement apparatus that allows one to repeat automatically in a precise manner the eluting or transporting of material from a reservoir, such as a column, to a second column or a second reservoir. A motor is driven, under controlled speed, to drive a piston into the first reservoir at a precise rate. As the piston enters the reservoir, material therein, such as a liquid, is forced upwardly through an aperture in the piston which co-acts with a tubular element connected to the second reservoir. Preferably, the bottom of the piston is concave and the passageway through the piston head begins at the apex of the concavity.

This invention relates to effecting separations and particularly to performing separations by liquid chromatography. More particularly, it relates to a transporting device that allows one to move fluid material in a reservoir at a steady rate from the reservoir to a separator, such as a packed column, or to a second reservoir or, if desired, the liquid or flowable mass may be transferred from successive containers ultimately to a separating column or the like. The invention will be understood by reference to the following description and drawings, all of which are given for illustrative purposes only and are not limitative.

In the drawings FIG. 1 is a front elevation, partly in section, showing two of the pumps of this invention;

FIG. 2 is a bottom plan view of the piston head taken on line 22 of FIG. 1;

FIG. 3 is a block circuit diagram illustrating how the motors may be driven to obtain a variety of flows and effects therefrom; and

FIGS. 4 to 7 show various flow patterns that can be effected by applying the principles and apparatus of this invention.

In performing separations by liquid chromatography, it is necessary to transport a liquid, such as a solvent, from a reservoir to a separation column that contains materials to be separated. In the course of such analytical work it is frequently desired to mix two or more liquids to effect elutions in a stepwise manner or with a smooth gradient. Hithertofore, ordinary pumping elements were used. With such it is necessary to change the speed of one pump relative to the second continuously to produce a gradient and to change the speed of the second pump continuously to maintain a constant flow rate. Such manipulations are complex and are very troublesome. These disadvantages are avoided by the use of the apparatus of this invention which provides smooth, constant repeatable flow rates regardless of back pressure or changes in back pressure. This assures that the same analytical conditions will be obtained even if the columns are changed, repacked or compressed during a run.

As can be seen in FIG. 1, a motor 10 is positioned to drive the screw 11. The motor 10 is a digital motor which is driven at a constant speed which is set by and controlled by the motor and speed control 12. At the end of the drive 3,62%,134 Patented Nov. 16, 1971 screw 11 furthermost from the motor 10 is a captive nut 13 which is provided to facilitate the removal of the pump ram 14 and the piston 15. In other words, should one desire to take out the piston assembly from the cylinder or reservoir 16, he merely twists the conventional captive nut 13 to the desired release position. This disengages the pump ram 14 from the drive screw 11 and allows the user to pull the pump ram and the piston head 15 out of cylinder 16.

It is to be noted that the piston head contains seal rings 17. These rings can be made of any of a wide variety of material that are inert to the materials, such as organic solvents, that are being employed in the given analysis. Cylinder 16 is normally constructed of precise bore glass tubing and the piston element 15 is normally constructed of poly(tetrafluoroethylene). In high pressure work cylinder 16 is constructed of an inert metal.

The motor, piston assembly and cylinder are held in cooperative relationship by means of a frame work comprising the bearing support 18, main extension rods 19 and the bottom support 20. The cylinder 16 can be mounted in cylinder flange 21, and the cylinder can be readily detached for cleaning.

In the cylinder head or plunger 15 there is an internal boring 22 the passageway of which co-acts with the passageway in the tubular element 23 to form an outlet for the material contained in cylinder 16 as it is forced upwardly with the downward movement of the pump ram 14 shown by the arrow in FIG. 1.

It is also to be noted that the bottommost surface of plunger 15 has a cut-away section 25 which is concave. As the cylinder moves downwardly, any air trapped in the cylinder is forced toward the apex of the concavity 25. Since the internal bore 22 has its inlet entrance at the very apex of concavity 25, all of the air will pass through the bore 22 and tubular element 23. In this way, entrapped air that would adversely affect the desired precise flow rates is avoided.

The concavity of plunger 15 is also shown in FIG. 2. There is also shown the inlet entrance 26 to internal bore 22.

As can be seen from FIG. 1, a cylinder 16, such as the cylinder to the left in FIG. 1, need not have any inlet in its bottom portion. However, if one wishes to use the pumps of this invention as a mixing device, the tubular element 23 of one cylinder 16 will be connected to an inlet 26 at the bottom of the next cylinder 16. This is shown in the cylinder 16 to the right in FIG. 1. Thus, the cylinder 16 to the left may contain one material and the cylinder to the right may contain an entirely different material. The operator can run the motors 10 for the respective cylinders at either the same or at different speeds and thereby effect the generation of linear and nonlinear gradients. Since the fiow rates of the different pumps are separately variable, the actual number of gradients and the flow rates at which the gradients can be produced is quite large. Further, the user can select a given gradient and can repeat it preceisely as many times as he desires. Still further, the user can terminate a given analysis or programming or modify it at any time during the analysis by simply changing or overriding the controls. Valves 28 may be placed in the lines at convenient location to provide for opening and closing passageways.

The tubular elements 23 can be constructed of any of a wide variety of materials. Generally, the tubing is a surgical grade narrow bore tubing made of poly(tetrafluoroethylene) Through the positive displacement pumps of this invention a very substantial saving in time is effected in liquid chromatography. Precisely controlled and exactly repeatable flow rates are achieved regardless of column back pressure. Flow rates that change during a run are avoided. The researcher no longer has to put up with columns that go dry or with plumbing failures or with collection volumes that are inconsistent. The researcher can very simply generate and repeat in exact manner any given solvent gradient. The motors are constant speed, digital motors that have both a short and long term constancy so that the flow rate is kept constant within :0.1%.

The term digital motor is used here to designate that class of synchronous motor which is driven with electronic circuits normally associated with digital computing elements, namely flip flop circuits and one shot millivibrators. Rotation of the motor is by discrete increments, normally 1.7 or per impulse received from the driving electronics. Motors and driving circiuts are available from Superior Electric of Bristol, Conn, trademark Slo- Syn. It is, of course, within the principles of this invention to use any of the many constant speed motors well known in the art and that any constant speed motor can be used in the system of this invention alone or in con junction with any other constant speed motor.

A block diagram (FIG. 3) showing how the digital motors can be driven at various speeds when taking the timing frequency from the normal 60 cycle per second power mains is presented. Using this scheme the maximum motor speed is achieved when the motors are ad vanced at a rate of 60 increments per second using the 60 cycle per second power mains as the pulse rate generator. Progressively slower speeds are obtained by dividing the 60 cycle per second pulse rate by standard electronic frequency dividers such as flip-flop circuits which are described in electronics text books. In this way 30 cycles per second, 15 cycles per second, etc., are obliterated for slower pumping speeds.

In FIG. 3, a 60 cycle per second source 29 can be used as such directly and sent to motors 30 and 31 through routes 32 and 33, respectively, if desired. The 60 c.p.s. source can also be fed to frequency dividers 34 each of which successively divides the frequency in half. Thus, at junction 35 a 30 c.p.s. source may be tapped through contact 36 which is part of the speed selection system for motor 30. Similarly, junction 37 may be used to use a 15 c.p.s. source for motor 30 by contacting element 36 with contact 38. Motor 31 may be similarly handled through contact 39 which is part of the speed selector limit for motor 31, there being contacts 40 for that motor. Thus, each motor may be given 60, 30, 15, 7.5, 3.75 or 1.875 c.p.s. sources as desired with the set-up shown in FIG. 3.

Elements 41 and 42 are pulse shapers and elements 43 and 44 are pulse inverters provided for the respective motors 31 and 30.

Other sources of regulated pulse rate could of course be used, such as a standard variable frequency oscillator so that the motor speed and, therefore, pump rate could be continuously variable. For the present application, however, the precision and repeatability of pulse rate is more important than the variety of ratios so the 60 cycle per second power mains frequency was selected.

It is to be appreciated that in this and in all reservoirs the conventional magnetic stirring elements 45 and 46 may be used to effect stirring and that various kinds of flowable materials may be mixed and/or transported including pastes, powders, liquids and the like. Also, it is to be appreciated that the piston head 15 does not rotate as the piston rides up and down, for the conduits 23 must remain fixed. Prevention or rotation is accomplished by means of pin 47, slot 48 and vertical plate 49 shown to the left in FIG. 1. Here a direct view is shown of plate 49 which has slot 48 in it in which slot pin 47 rides. The captive nut and piston ram are shown in dotted lines here, since those elements are behind plate 49 in this view. Pin or rod 47 is connected at its far end to the captive nut 13 as shown in FIG. 1 to the right while at the end shown to the left, it is free to ride up and down in slot 48 the walls of which prevent rotation of the piston. The slot 48 can, of course, have any length desired. For convenience, the plate 49 is omitted in the unit shown at the right of FIG. 1.

Using the above described regulation of the motors 31 and 30, one can use the same solvent in both or all the connected units in which event FIG. 4 represents the straight line fiow. If the first pump contains solvent 1 and the second pump contains solvent 2 and the second pump is to follow the first, then the flow pattern that is obtained is that given in FIG. 5. If different solvents are used and the second pump is not to follow the first but the first is to discharge into the second, then the flow pattern will be a linear gradient such as shown in FIG. 6, if the two pumps are being run at the same speed. If the speeds are different and the first pump is set at a rate slower than the second pump, then the non-linear gradient given in FIG. 7 is obtained. The slope given in FIG. 7 is reversed if the first pump runs faster than the second. It can be seen that a large variety of gradients can be produced and that any given gradient can be precisely repeated as long as necessary.

While the invention has been disclosed herein in connection with certain embodiments and certain structural and procedural details, it is clear that changes, modifications or equivalents can be used by those skilled in the art; accordingly, such changes within the principles of the invention are intended to be included within the scope of the claims below.

We claim:

1. A device for exerting pressure on a liquid contained in a vessel to effect a positive, continuous displacement of said liquid out of said vessel in a straight-line flow which device comprises a piston having a concave bottom and containing an internal bore running from the bottom of said piston to its top, said bore having an aperture substantially at the apex of said concavity whereby trapping of gaseous material, such as air, is prevented, said piston being adapted to be driven at a constant speed in said vessel in a precise manner by a rotating drive element, said vessel having an orifice in conduit relationship with said bore and affording said removal of said liquid from said vessel at a constant rate.

2. A device in accordance with claim 1 in combination with a tube in conduit relationship with the outlet of said internal bore at the top of said piston.

3. A device in accordance with claim 2 in which said tube is also in conduit relationship with a second vessel.

References Cited UNITED STATES PATENTS 1,447,963 3/1923 Coleman 230221 X 2,284,645 6/1942 Duffy 230-221 X 2,452,369 10/1948 Gravenhorst et a1. 92-18l X 2,856,116 10/1958 Hogan 23022l X 2,953,119 9/1960 Geyer 92-18l X 2,966,145 12/1960 Froehlich 9218l X 3,331,328 7/1967 Smith et al. 103-225 X WILLIAM L. FREEH, Primary Examiner US. Cl. X.R. 222-390

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