US3306229A

US3306229A - Pump apparatus and method of operation thereof

Info

Publication number: US3306229A
Application number: US445480A
Authority: US
Inventors: William J Smythe
Original assignee: Technicon Instruments Corp
Current assignee: Bayer Corp
Priority date: 1965-04-05
Filing date: 1965-04-05
Publication date: 1967-02-28
Anticipated expiration: 1984-02-28
Also published as: DE1553242C3; DE1553242A1; BE678986A; GB1123122A; SE350100B; CH476920A; DE1553242B2

Description

Feb. 28, 1967 w. J. SMYTHE PUMP APPARATUS AND METHOD OF OPERATION THEREOF 4 Sheets-Sheet 1 Filed April 5, 1965 .522 see.

' D ".356sec.

7707c (Sec) INVENTOR.

, W/AL/4M J. s/urrms BY C(YL ATTORNEY Feb. 28, 1967 r w. J. SMYTHE 3,306,229 PUMP APPARATUS AND METHOD OF OPERATION THEREOF 4 Sheets-Sheet 2 Filed April 5, 1965 INVENTOR WILL /AM 1/. 5/14/7795 Feb. 28, 1967 w. J. SMYTHE 3,306,229

PUMP APPARATUS AND METHOD OF OPERATION THEREOF Filed April 5, 1965 4 Sheets-Sheet 5 INVENTOR. W/Ll/AM J. SMVTHE ATTORNEY Feb. 28, 1967 w. Ji SMYTHE PUMP APPARATUS AND METHOD OF OPERATION THEREOF 4 Sheets-Sheet 4 Filed April 5, 1965 INVENTOR. W/L L IAM J. SM VT/IE ATTORNEY United States Patent Ofi ice 3,306,229 PUMP APPARATUS AND METHOD OF OPERATION THEREOF William J. Smythe, Rye, N.Y., assignor to Technicon Instruments Corporation, Chauncey, N.Y., a corporation of New York Filed Apr. 5, 1965, Ser. No. 445,480 20 Claims. (Cl. 103-149) The invention relates to fluid pumps, and more particularly to peristaltic proportioning pumps which are advantageously utilized in continuous stream analytical systems.

In systems of this nature, a continuous stream of a sample liquid, which stream may be a continuous monitoring stream, or may be a continuous stream of sequential liquid samples, is continuously mixed, in a predetermined proportion with one or more reagents, and otherwise processed to provide a color reaction, the optical density of which is responsive to the concentration of a substance in the original sample. Such a system was initially disclosed in US. 2,797,149, granted to L. T. Skeggs on June 25, 1957. Customarily, the continuous stream of sample plus reagent is divided into sequential segments, each succeeding sample segment being spaced from its preceding segment by a gas segment. Each'segment of sample plus reagent is then mixed up as it flows along in the stream, as shown in U.S. 2,933,293, granted to A. Ferrari, Jr. on April 19, 1960. The continuous streams of sample and reagent are supplied in a predetermined proportion to a junction by a proportioning pump, such as is shown in US. 2,935,028, granted to A. Ferrari, Jr. and J. Isreeli on May 3, 1960. In such a pump a plurality of pump tubes are disposed in side by side relation, and are concurrently, progressively occluded by a series of rollers, to positively displace fluids through these pump tubes. The relative proportions of volumetric rate of flow of these fluids are substantially determined by the relative inner cross-sectional areas of the respective tubes.

It has been discovered that the relative proportions of volumetric rate of flow through the tubes does not remain constant during the period of operation of the pump. While the leading roller fully occludes the pump tubes, the relative proportions are constant. However, as the leading roller rises away from the pump tubes the proportions will change if the tubes are of different internal diameter. This transient change in proportion between the sample and the reagents may afiect the accuracy of the analysis system, which accuracy is premised on constant proportions.

Therefore, it is the object of this invention to provide a pump system which achieves uniform proportional mixing of the sample and the reagents added thereto.

A feature of this invention is the provision of a peristaltic pump having a plurality of rollers and a plurality of resiliently flexible pump tubes for displacing a sample and one or more reagents respectively to form a resultant stream which has a constant proportion of sample and reagent per predetermined unit volume of such resultant stream.

Another feature of this invention is the provision of a peristaltic pump having a plurality of rollers and a plurality of pump tubes, one tube for displacing sample, one or more tubes for displacing one or more reagents respectively, and a tube for displacing a gas, the outlets of said tubes being connected to a junction means, and means to admit a volume of the gas from its tube to said junction means in synchronism with the withdrawal of each roller from said tubes.

In accordance with thepresent invention the resiliently flexible pump tubes through which liquids are displaced 3,306,229 Patented Feb. 28, 1967 by the periodic action of tube occluding means, are connected to one or more conduits for the flow of said liquids and provision is made for the delivery of air into one of said conduits in constant timed relation to the disengagement of the tube occluding means from the pump tubes.

These and other objects, features and advantages of this invention, will be more fully understood from the following description considered in conjunction with the accompanying illustrative drawing, in which:

FIG. 1 is a perspective diagram of a pump rollerand a pump tube;

FIG. 2 is a diagram of a cross-section of the roller and tube of FIG. 1 taken along plane 2-2;

FIG. 3 is a diagram similar to FIG. 2;

FIG. 4 is a chart of the volumetric flow rate through two pump tubes in a conventional pump system vs. time;

FIG. 5 is a partial view in elevation of the front of a pump embodying this invention;

FIG. 6 is a partial view in plan of the pump of FIG. 5;

FIG. 7 is a partial view in elevation of the downstream side of the pump of FIG. 5;

FIG. 8 is a partial view in elevation of the upstream side of the pump of FIG. 5;

FIG. 9 is a diagrammatic view of another pump embodying this invention; and

FIG. 10 is a diagrammatic view of a modification of the apparatus of FIG. 5.

The following mathematical analysis will serve as a possible explanation of the problem which is solved by the present invention pursuant to the objects and features stated above. It is to be understood, however, that I do not wish to be held to this explanation since the solution to said problem might be accounted for by some other theoretical or practical considerations.

Turning now to FIG. 1, a pump tube 12 is shown as having a square cross-section for the purpose of the following analysis of the conventional peristaltic pump system, rather than the conventional circular cross-section. Very little error results from this approximation because this analysis is primarily concerned with the relative effects of different sizes of pump tube. The volume of the tube occluded by a roller 14 is shown in FIG. 2, wherein R equals the radius of the roller 12; D equals the internal diameter of the pump tube 10; w equals the wall thickness of the tube 10; and r equals the thickness of the rail. The depth of penetration is indicated as y and the area of the tube carried by the roller is very nearly the shaded area indicated. This is the cross-section of the inner part of the tube occluded by the roller, including that part occluded by the tube wall. The small gap G between the roller and the tube wall renders this an approximation.

The area of the shaded portion is:

It may be noted that the maximum depth of the roller y is reached at D|(2wr), although the tube is actually closed when y=D.

The manner in which y changes with time is shown in FIG. 3. Here, two

rollers

14A and 14B are shown. The roller 14A is shown at its y position, and is also directly below the pivot point 16, about which it pivots as it withdraws from the tube. The roller lifts from the rails, pivoting about point 16 on a radius 1 to finally leave the tube at the position shown at 14A.

The vertical displacement of the roller as a function of time, indicated as Z(t) is equal to p(1COS 18); so that W) equals ymax or ymax' P( cos B)- The angle at which this roller leaves the tube depends on the particular tube, noting that Table 1, infra, lists values of 5 for several commercial sizes of pump tubes; where R=.l87, w=.033, and R=.045".

TABLE 1 D Ymux=D+.02l 9 The largest size of pump tube customarily used has D=.1l0". Up to this size the 2 cos 321 and Assuming 0c is the angular velocity of the roller as it comes off the rails and v is its linear velocity along the rails, then In one commercial pump y =D=.02l", =0.5", and v=2/3 in./sec., so that y(t)=D+.02l"(4/9)(t The most pertinent times are the time i=0 (i.e., y=y the time 1 at which the tube begins to open (i.e., y=D); and the time 1 at which the tube is fully open (i.e., y=0). These times are given in Table 2, together with V and V (i.e. volume at t The last column shows the ratios of maximum tube volume occluded (V to the volume of the segment between two successive rollers (D 1), assuming 1:2" as in one commercial pump. Except for the very small tube sizes, where the rate of change of area A with y is large, this ratio increases slowly with D.

In FIG. 4 are plotted the time dependence of volumetric fiow rate for two different sizes of pump tubes, D=.035 and D=.100", having flow rates of .42 ml./ min. and 3.40 ml./min. respectively. The pump has 5 rollers, so that a roller leaves the rails every 3 seconds. At time i=0 it is assumed that a roller is directly beneath the pivot point thereby providing maximum occluded volume. The area under each curve represents the total liquid delivered to the system in any given time through the respective tube.

The fiow continues in both tubes until t :.218 sec., when the tubes begin to open. The flow then ceases as the occluded portion of the tube fills. Initially, this portion fills from the upstream segment behind it, but when the rate of change of the occluded volume exceeds the delivery rate of the trailing segment, liquid is drawn back from the downstream system to fill the void. It is assumed that the flow rate drops to zero, rather than takes on a negative value. At time t which is different for each size of tube, the roller leaves the tube and the previously occluded volume is now filled and the flow rates return to their initial values until the next succeeding roller leaves the rails.

Consider the amounts of each liquid entering the system during a given interval, say in one second, during the three second cycle provided by the rollers, The proportion between the amounts depends upon where in the cycle the interval is selected. For example, if the interval from t:0 to t=l is chosen, relatively more sample, assuming the smaller flow rate to be the sample, then reagent enters the system, compared with the one second interval between t=l and 2:22. In fact, the concentration of sample in the former case is .154 while in the latter case it is .124, a difference of some 25%! In the case of smaller sample tubes, the effect is even more pronounced.

A first solution to this problem is to divide the stream of sample plus reagent into constant length (and thereby volume) segments; each segment being equal to, or an integral multiple of, the roller period. For example, if the period between rollers is three seconds, the segments may be 3, 6, 9 seconds long.

Each segment of sample plus reagent is then intramixed to provide a uniform proportion throughout the length of such segment.

The presently preferred mode of practicing my invention will be described with respect to FIGS. 5 through 8. A peristaltic pump 50 is similar to that shown in U.S. 2,935,028. It includes a housing 52; a platen 54 supported by a plurality of springs 56 on the housing; a roller assembly 58 supported above the platen; two tube mounting blocks 60 and 62 respectively supported on opposite ends of the platen; and a plurality of pump tubes 64, each held between the mounting blocks above the platen and below the roller assembly.

The roller assembly comprises a frame plate 66 on which two endless sprocket chains 68 (only one shown) are mounted for movement. These chains carry and thereby actuate a plurality of rollers 72 which are mounted by bearing pins which are fixed in the links of the chains. The chains are driven by sprocket wheels fixed to a rotary shaft 74 which is driven by a chain 76 coupled to a motor within the housing. As each roller is carried under the roller assembly, it occludes the pump tubes therebelow on the platen until it advances to a position below the shaft 74 and is then carried by the chains upwardly away from the tubes. The shaft 74 is identical to the pivot point 16 described with respect to FIG. 3.

A bracket 80 is mounted to the top of the housing, and has a horizontal portion 82 and a vertical portion 84. Mounted on the horizontal portion is an anvil block 86 which has a longitudinal channel 88 and an intersecting lateral channel 90. The pump tube for displacing air is disposed in the longitudinal channel downstream of the roller assembly. An arm 92 is pivotally mounted by a bearing 93 to the vertical portion 84. One end of the arm carries a lateral pin 94 which is adapted to enter the lateral channel and to occlude the pump tube disposed in the longitudinal channel 88. A vertical bracket 96 is fixed below the horizontal portion 82, and a tension spring 98 is fixed between a hole in the end of the arm and a hole in the bracket 96 to bias the arm to occlude the air pump tube.

The other end of the arm has a cam follower surface 100 formed thereon. Each bearing pin of the rollers 72 passing into the sprocket chain 68 has an extension 102 which is adapted to engage and to depress the cam surface and to pivot the arm, to thereby lift the pin 94 from the air pump tube. The interval during which the air pump tube is opened is determined by the length of the cam follower surface.

Each roller operates the arm to open the air pump tube, and thus this tube is valved in synchronism with the passage of the rollers. The downstream ends of the pump tube for the air 64A and the pump tube for the reagent 64B are coupled together by a first stream junction means 104 which has an outlet tube 106. Thus, when the air tube 64A is closed, a stream of reagent passes out the outlet tube 106. Once during each period that a roller 72 leaves the pump tubes, but the succeeding roller has not, the arm 92 is actuated to open the air tube 64A to pass a volume of air to segmentize the reagent stream flowing through the outlet tube 106. The downstream ends of the pump tube for the sample 64C and the first outlet tube 106 are coupled together by a second stream junction means 108 which has an outlet tube 110. The sample stream is thus added to the segmentized reagent stream. The valving of the air tube is in constant phase with the withdrawal of the rollers from the pump tubes. Thus, the length of each segment of sample plus reagent is constant, and the total content of sample plus reagent is constant from segment to segment, even though the proportion of sample to reagent within each segment may vary due to the elfect of the pump roller leaving the pump tubes and these pump tubes expanding their inner volumes.

It is customary to make the air segments inserted or added into a liquid stream at least the volume of the liquid segments. This is done to insure that the air fully occludes the inner diameter of the tube conveying the liquid stream. Since the volumetric rate of flow of the reagent stream is usually much greater than the volumetric rate of flow of the sample stream, it is advantageous to initially segmentize the reagent stream. The air segments carried in the reagent stream are then sure to continue to fully occlude the tube when the sample stream is subsequently added to the segmentized reagent stream. If the sample stream were segmentized initially, the air segments carried in such. a stream might not be large enough to fully occlude the tube when the reagent stream was added to such a segmentized sample stream. If the volumetric rate of fiow of the sample stream is large enough, then such a sample stream may be initially segmentized, since the air segments carried in such a segmentized air stream will be great enough to continue to occlude the tube when the reagent stream is added thereto.

It will be appreciated that while the air must be added regularly and periodically, the period need only be an integral multiple of the period of the rollers. Thus, if the period of the rollers is 3 seconds, the period of the air addition may be 3, 6, or 9 etc. seconds.

It is possible to add the sample stream to the reagent stream and to segmentize the resultant stream concurrently, by coupling the outlets of the air, reagent and sample pump tubes to an integral junction means having three inlets, to which the pump tube outlets are respectively coupled, and one outlet. In such a case, however, the air segment must pass through the junction means while the sample and reagent tubes are fully occluded. If the air segment is passing through the junction means while the sample or reagent pump tube is changing voltime, with a corresponding change in stream pressure, the air segment may shift its location in the resultant stream, and may even temporarily flow upstream into such a reagent or sample pump tube.

It is also possible and desirable to segmentize upstream of the pump. An arrangement for segmentizing a large sample stream, as the sample is aspirated from the sample supply, is shown in the US. patent application of A. Ferrari, S.N. 185,303, now Patent No. 3,186,235, assigned to the assignee of this application. In such an arrangement, as shown in FIG. 10, a pump 150 has an air pump tube 152A, a sample pump tube 152B and a reagent pump tube 152C. The downstream outlet of the air pump tube 152A is coupled to a tube 154 having an outlet end 156 in fluid flow communication with a sample off-take tube 153 slightly upstream of the inlet end 160 of this off-take tube. Both the air tube 154 and the sample otT-take tube 156 are inserted into the sample supply container 162. The outlet end of the off-take tube 158 is coupled to the inlet end of the sample pump tube 152B. The downstream outlet ends of the sample pump tube 152B and the reagent pump tube 152C are coupled to a junction means 164 having an outlet tube 166.

By such an arrangement, which is claimed in the Ferrari application, almost the entire length of the sample off-take tube and the sample pump tube is cleansed by the air segments. This air pump tube is valved, according to the principles of my invention, downstream of the pump, yet upstream of the outlet 156 by a valve system similar to that shown in FIG. 5, comprising an arm 92 and a pressure applying pin 94, operated regularly periodically, the period of the air segments being equal to the period of the rollers of the pump. By this arrangement a twofold advantage is obtained of cleansing substantially the entire sample system and providing constant proportions of sample to reagent within each segment of sample plus reagent.

The outlet tube is coupled to a mixing coil, not shown, such as is disclosed in US 2,933,293, supra, wherein the contents of each segment of sample plus reagent is intramixed to make the proportion of sample to reagent constant throughout the length of such segment.

It will be appreciated that in lieu of the mechanical valving arrangement for the air pump tube here shown, a solenoid operated valve which is energized by a microswitch which in turn is actuated by the pump rollers may be utilized.

Although the presently preferred embodiment utilizing a positively operated valve in the gas pump tube has been described with respect to FIGS. 5 through 8, another embodiment will be described with respect to FIG. 9 which does not require a positively operated valve. In this embodiment the pump 200 has pump rollers 202 which occlude pump tubes 204 as previously described. The pump tube 204A for the sample and the pump tube 204B for the reagent are respectively connected to the inlets of a stream junction means 206 which has an outlet tube 208. The pump tube 204C for air, which is customarily made of a compressible resilient material such as polyvinylchloride sold under"the trademark Tygon is connected a tube 210 of material having a relatively low free surface energy, such as fiuorinated hydrocarbon sold under the trademark Teflon. The downstream end of the tube 210 is connected to a tube 212 of a material having a relatively high free surface energy, such as glass. The downstream end of the tube 208 is brought through the wall of the tube 212 adjacent its upstream end, with the outlet of the tubee 208 opening towards the downstream end of the tube 212.

The rollers 202 continuously displace sample and reagent through the

tubes

204A and 204B respectively to the junction means 206 and through the outlet tube 208 into the segmentizing tube 212. The stream of sample plus reagent flows downstream in the direction of reduced line pressure through the segmentizing tube 212 from the outlet tube 208; and not upstream in the direction of increased line pressure past the end of the relatively highly free energy surface of the tube 212 which provides a relatively high surface adhesion to this sample plus reagent. The rollers 202 also continuously displace air through the tube 204C into the tube 210. However, this air does not continuously flow into the tube 212, due to the relatively small inner diameter and the obstruction provided by the sample plus reagent in the end of the tube 212. The air temporarily hangs up at the junction between the

tubes

212 and 210 which is the demarcation between relatively high free energy surface and relatively low free energy surface and is compressed by the succeeding air displaced through the tube 2040. Eventually the pressure of the air reaches a level adequate to force a volume of air into the tube 212, segmentizing the stream of sample plus reagent also flowing thereinto from the tube 208. When the air pressure falls at the junction, the flow of air halts temporarily until the pressure is built up again. The period between air segments is a function of the rate at which air is pumped by the pump tube 204C and may be adjusted so that this period is equal to the period between pump roller departures from the pump tubes. The downstream end of the segmentizing tube 212 is coupled to the mixing tube 214, as previously described.

It will be appreciated that while a peristaltic type pump utilizing a plurality of rollers has been illustrated, any tube occluding means which is regularly periodically operated, such as a cam, or a series of fingers, may be utilized.

It also will be appreciated that while the means for supplying the segmentizing air has been herein disclosed as a pump tube operated by the same pump which operates the sample and reagent pump tubes, an independent source of air, such as a reservoir under pressure with a constant volumetric rate of flow outlet valve may be substituted therefore in the embodiment of FIG. 5. Alternatively, the inlet of the reagent or sample pump tube may regularly periodically be coupled to the atmosphere, as by the mechanical lifting of the tube inlet from its liquid supply and the exposure of this inlet to the atmosphere.

It further will be appreciated that in the embodiment shown in FIG. 5, the first junction means 104 and the second junction means 108 together constitute a junction means for the air, reagent and sample tubes. In the embodiment shown in FIG. 9, the junction means 206, the tube 208 and the tube 212 together constitute a junction means for the air, reagent and sample tubes. In the embodiment shown in FIG. 10, the first junction of the

tubes

154 and 158 and the second junction means 162 together constitute a junction means for the air, reagent and sample tubes.

While I have referred to the mixing of the sample liquid and the reagent liquid in each segment as a result of the flow of the segmented stream through a mixing coil, mentioning in that connection United States Patent No. 2,933,293 of Andres Ferrari, Jr., it is to be noted that by reason of the uniform proportion of total sample liquid to total reagent liquid in each segment resulting from the above described constant periodic introduction of the segmenting air, considerable less intermixing of the liquids in each segment is required than was heretofore the case. Also, the segmented fluid stream including the air bubbles, i.e., the air segments is preferably transmitted through the flow cell of the colorimeter as a result of which the flow cell is cleansed by the air bubbles, the flow cell being preferably of the tubular type described in the United States patent application of William J. Smythe and Morris H. Shamos, Serial No. 369,695, filed May 25, 1964, and assigned to the assignee of my present application. It will be understood, therefore, that the colorimeter controlled recording of each sample under analysis will include a plurality of peaks of uniform value for each sample recorded instead of a single peak value as is the case when the air bubbles are removed before the fluid stream enters the flow cell. The decrease in mixing time because of less intermixing of the liquids and the cleansing of the flow cell by the air bubbles each contributes to a decrease of the time required for each analysis.

Thus, it is seen that the pump embodying the present invention is well adapted to accomplish the object thereof in the several forms or embodiments of the invention described above. It will be understood, however, that the invention may be embodied otherwise than as hereinbefore shown or described and that in the illustrated and described embodiments certain changes in the details of construction and in the arrangement of parts may be made and will occur to persons skilled in this art, in view of the present disclosure, without departing from the underlying idea or principles of this invention. Accordingly, there is no limitation to the precise construction herein shown or described except to the extent which may be required by the scope of the appended claims considered with reference to the prior art.

What is claimed is:

1. A peristaltic pump apparatus, comprising: at least two resiliently compressible pump tubes; a plurality of compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means; each of said two tubes having an inlet for fluid flow coupling to a respective source of fluid, and an outlet for the discharge of the respective stream of fluid; and means for continuously adding together the streams of liquids of said two tubes into a resultant stream and for regularly periodically adding a volume of an inert different fluid to at least one of the streams to provide a segmentized resultant stream, said addition of each volume of the different fluid occurring at a constant interval of time after the addition of the next preceding volume of the different fluid and prior to the addition of the next succeeding volume of the different fluid; said constant interval of time between successive additions of the different fluid being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes.

2. A peristaltic pump apparatus, comprising: at least two resiliently compressible pump tubes; a plurality of compressing means, operable cyclically and a sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means; each of said two tubes having an inlet for fluid flow coupling to a respective source of fluid, and an outlet for the discharge of the respective stream of fluid; and means for continuously adding together the streams of liquids of said two tubes into a resultant stream and for regularly periodically adding a volume of an inert different fluid to at least one of the streams to provide a segmentized resultant stream, said addition of each volume of the different fluid occurring at a constant interval of time after the addition of the next preceding volume of different fluid and prior to the addition of the next succeeding volume of the different fluid, and including a normally closed valve which is coupled to a source of the different fluid and which is regularly periodically opened to permit the passage therethrough, and said addition, of a volume of the different fluid; said constant interval of time between successive additions of the different fluid being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes.

3. A peristaltic pump apparatus, comprising: at least two resiliently compressible tubes; a plurality of rollers,

operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of fluid, and an outlet for the dicharge of the respective stream of fluid; and means for continuously adding together the streams of liquids of said two tubes into a resultant stream and for regularly periodically adding a volume of an inert different fluid to at least one of the streams to provide a segmentized resultant stream, said addition of each volume of the different fluid occurring at a constant interval of time after the addition of the next preceding volume of different fluid and prior to the addition of the next succeeding volume of the different fluid, and including a normally closed valve which is coupled to a source of the different fluid and which is regularly periodically opened to permit the passage therethrough, and said addition, of a volume of the different fluid, by a valve operating mechanism having an actuator with a cam follower surface which is engaged by at least one of said rollers during its cyclical operation; said constant interval of time between successive additions of volume of the different fluid being an integral mutiple of said constant interval of time between successive disengagements of said rollers from said tubes.

4. A peristaltic pump apparatus, comprising: at least two resiliently compressible tu-bes; a plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of fluid, and an outlet for the discharge of the respective stream of fluid; and means for continuously adding together the streams of liquids of said two tubes into a resultant stream and for regularly periodically adding a volume of an inert different fluid to at least one of the streams to provide a segmentized resultant stream, said addition of each volume of the different fluid occurring at a constant interval of time after the addition of the next preceding volume of different fluid and prior to the addition of the next succeeding volume of the different fluid, and including a first conduit having a first inlet for receiving the stream to be segmentized, an outlet for discharging the segmentized stream, a second inlet upstream of said first inlet, and an inner surface having a relatively high free surface energy characteristic, a second conduit having a relatively low free surface energy characteristic, an outlet in end to end engagement with said second inlet of said first conduit to form a sharp demarcation in free surface energies, and an inlet coupled to a source of the different liquid under pressure; said constant interval of time between successive additions of volume of the different fluid being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tube.

5. A peristaltic pump apparatus, comprising: at least two resiliently compressible tubes; a plurality of rollers, operable cyclic-ally and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid; means coupled to said outlet of one of said tubes for regularly periodically adding a volume of an inert gas to the stream discharged thereby to segmentize this stream, and also coupled to said outlet of the other of said tubes to continuously add the stream discharged thereby to the segmentized stream to provide a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tubes.

6. A peristaltic pump apparatus, comprising: at least two resiliently compressible tubes; a plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid; means coupled to said outlet of one of said tubes for regularly periodically adding a volume of an inert gas to the stream discharged thereby to segmentize this stream, and also coupled to said outlet of the other of said tubes to continuously add the stream discharged thereby to the segmentized stream to provide a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; and including a normally closed valve which is coupled to a source of the different fluid and which is regularly periodically opened to permit the passage therethrough, and said addition, of a volume of the different fluid, by a valve operating mechanism having an actuator with a cam follower surface which is engaged by at least one of said rollers during its cyclical operation; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tubes.

7. A peristaltic pump apparatus, comprising: at least two resiliently compressible tubes; a plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid; means coupled to both of said outlets of said tubes for continuously adding together the streams respectively discharged thereby, and for regularly periodically adding a volume of an inert gas to this resultant stream to provide a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time l 1 between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagement of said rollers from said tubes,

8. A peristaltic pump apparatus, comprising: at least two resiliently compressible tubes; a plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said two tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurringat a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; each of said two tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid; means coupled to both of said outlets of said tubes for continuously adding together the streams respectively discharged thereby, and for regularly periodically adding a volume of an inert gas to this resultant stream to provide a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; and including a first conduit having two inlets and an outlet, one outlet of said first conduit being coupled to one of said pump tube outlets, the other outlet of said first conduit being coupled to the other one of said pump tube outlets, thereby to continuously add one stream to the other stream to discharge the resultant stream through said outlet, a second conduit having a first inlet coupled to said outlet of said first conduit for receiving the resultant stream, an outlet, a second inlet upstream of said first inlet, and an inner surface having a relatively high free surface energy characteristic, a third conduit having a relatively low free surface energy characteristic, an outlet in end to end engagement with said second inlet of said second conduit to form a sharp demarcation in free surface energies, and an inlet coupled to a source of gas under pressure; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tubes.

9. A peristaltic pump apparatus, comprising: at least each for sequentially, progressively compressing said tubes a plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; said first and second tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid, said third tube having an inlet for fluid flow coupling to a source of gas, and an outlet for the discharge of the respective stream of gas; means coupled to said outlets of said first and second tubes for continuously adding together the streams respectively discharged thereby to form a resultant stream; and valve means coupled between said outlet of said third tube and said outlet of said first tube for regularly periodically passing a volume of gas from said third tube to the stream discharged by said first tube to provide a segmentized resultant stream, said passage of each volume of gas occurring at a constant interval of time after the passage of the next preceding volume of gas and prior to the passage of the next succeeding volume of gas; said constant interval of time between successive passages of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tubes.

10. A peristaltic pump apparatus, comprising: at least streams respectively discharged thereby to form a resulta plurality of rollers, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said rollers from said tubes occurring at a constant interval of time after the disengagement of the next preceding roller and prior to the disengagement of the next succeeding roller; said first and second tubes having an inlet for fluid flow coupling to a respective source of liquid, and an outlet for the discharge of the respective stream of liquid, said third tube having an inlet for fluid flow coupling to a source of gas, and an outlet for the discharge of the respective stream of gas; means coupled to said outlets of said first and second tubes for continuously adding together the streams respectively discharged thereby to form a resultant stream; conduit means having an outlet tubular portion having an inner surface with a relatively high free surface energy characteristic, a first inlet tubular portion having an inner surface with a relatively low free surface energy characteristic, said outlet and first inlet tubular portions being in end to end engagement to form a sharp demarcation in free surface energies, and a second inlet tubular portion passing into said outlet tubular portion immediately downstream of said sharp demarcation; the outlet of said third pump tube being coupled to said first inlet portion of said conduit, said second inlet portion of said conduit being coupled to said adding means for receiving the resultant stream therefrom, whereby the resultant stream flows as a continuous stream through said first inlet portion of said conduit normally blocking the flow of gas through said conduit at said demarcation in free surface energies, the blocked gas normally being compressed by said rollers, the compressed gas regularly periodically developing adequate pressure to pass a volume of gas through said conduit; said constant interval of time between successive passages of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said rollers from said tubes.

11. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: continuously adding the streams from said two tubes together to form a resultant stream, and regularly periodically adding a volume of a gas to one of the streams to form a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes.

12. A peristaltic pump apparatus, comprising: a pump having a plurality of resiliently compressible tubes, and tube compressing means periodically engageable with said tubes progressively in the direction of their lengths and periodically disengageable from said tubes, for the pumping action, each of said tubes having an inlet for the admission of a liquid stream and an outlet for the discharge of a liquid stream therefrom during said pumping action, and means operable periodically in constant time relation to said periodic disengagement of said compressing means from said tubes for introducing gaseous fluid into at least one of said liquid streams for forming a fluid stream containing flowing segments of liquid separated from each other by intervening flowing segments of gaseous fluid.

13. A peristaltic pump apparatus, comprising: a pump having a plurality of resiliently compressible tubes, and tube compressing means periodically engageable with said tu-bes progressively in the direction of their lengths and periodically disengageable from said tubes, for the pumping action, each of said tubes having an inlet for the admission of a liquid stream and an outlet for the discharge of a liquid stream therefrom during said pumping action, a conduit in fluid flow communication with said tubes for receiving liquids from said tubes during said pumping action, and means operable periodically in constant time relation to said periodic disengagement of said compressing means from said tubes for introducing gaseous fluid into at least one of said liquid streams for forming a fluid stream containing flowing segments of liquid separated from each other by intervening flowing segments of gaseous fluid.

14. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: continuously adding the streams from said two tubes together to form a resultant stream, and regularly periodically adding a volume of a gas to one of the streams to form a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and transmitting the gas-segmented stream, including the segmentizing gas through the flow cell of a colorimeter-recorder.

15. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a volume of a gas to one of the streams to form a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said comi4 pressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a resultant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments.

16. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a volume of 'a gas to one of the streams to form a segmentized resultant stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a result-ant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments, and transmitting the gas-segmented stream, including the segmentizin-g gas, through the flow cell of a colorimeter-recorder.

17. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a gas to said stream of reagent liquid to form a segmented stream, said 'addition'of each volume of gas occurring at a con stant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding vol-ume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a resultant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments.

18. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube com pressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes, occurring at a constant interval of time after the disengagement of the next preceding compressing means, and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a gas to said stream of reagent liquid to form a segmented stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas, said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a resultant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments, and transmitting the gas-segmented stream, including the segmentizing gas, through the flow cell of a colorimeter-recorder.

19. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a gas to said stream of sample liquid to form a segmented stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a resultant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments.

20. A method of processing fluids by a peristaltic pump having at least two tubes and a plurality of tube compressing means, operable cyclically and sequentially, each for sequentially, progressively compressing said tubes in the direction of their lengths in a pumping action to displace fluids respectively therethrough as respective streams and then sequentially disengaging from said tubes, the disengagement of each of said compressing means from said tubes occurring at a constant interval of time after the disengagement of the next preceding compressing means and prior to the disengagement of the next succeeding compressing means, said method comprising: transmitting a stream of sample liquid through one of said tubes and a stream of reagent liquid through another of said tubes by said operation of said tube compressing means, regularly periodically adding a gas to said stream of sample liquid to form a segmented stream, said addition of each volume of gas occurring at a constant interval of time after the addition of the next preceding volume of gas and prior to the addition of the next succeeding volume of gas; said constant interval of time between successive additions of volumes of gas being an integral multiple of said constant interval of time between successive disengagements of said compressing means from said tubes, and thereafter adding said two streams in a conduit and thereby forming a resultant segmentized stream comprising successive flowing segments of sample liquid and reagent liquid separated by intervening gas segments, and transmitting the gas-segmented stream, including the segmentizing gas, through the flow cell of a colorimeter-recorder.

References Cited by the Examiner UNITED STATES PATENTS 2,797,149 6/1957 Skeggs 23-230 2,865,303 12/1958 Ferrari et al. 103-149 2,893,324 7/1959 Isreeli et al 103-149 2,922,379 1/1960 Schultz 103-149 2,933,293 4/1960 Ferrari 259-4 2,935,028 5/1960 Ferrari et al 103-149 3,101,674 8/1963 Weiskopf et al. 103-149 3,186,235 6/1965 Ferrari 73-423 DONLEY J. STOCKING, Primary Examiner. W. J. GOODLIN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,306 ,229 February 28 1967 William J. Smythe It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shovm below:

Column 11, line 46, cancel "each for sequentially, prog sively compressing said tubes" and insert a first, a second and a third resiliently compressible tubes; Column 12, line 4 cancel "stream respectively discharged thereby to form a result" and insert a first, a second and a third resiliently compressible tubes;

Signed and sealed this 12th day of August 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM Attesting Officer Commissioner of Patents