GB2212612A

GB2212612A - Procedure and apparatus for the dosage of a flowable substance

Info

Publication number: GB2212612A
Application number: GB8826129A
Authority: GB
Inventors: Henrik Johansson; Keijo Maekelae; Mikk Miettinen
Original assignee: Kone Corp
Current assignee: Kone Corp
Priority date: 1987-11-17
Filing date: 1988-11-08
Publication date: 1989-07-26
Anticipated expiration: 2008-11-08
Also published as: JPH01199639A; IT8812584A0; JPH0369576B2; FI875078A0; FI78664C; AU609895B2; SE8804140D0; IT1225724B; NL8802779A; CH677405A5; FI78664B; BE1003785A4; FR2623182A1; GB8826129D0; SE8804140A; AU2518788A; SE8804140A0; GB2212612B; DE3836208A1

Description

2 12 6 1 '2- PROCEDURE AND APPARATUS FOR THE-DOSAGE OF A FLOWABLE

SUBSTANCE.

The present invention concerns a procedure for the dosage of a flowable substance, such as a liquid or a gas. The invention relates especially to the dosage of substances in small quantities in conjunction with chemical wet analyses etc. in laboratories.

A typical solution used for the dosage of' small quantities of fluids is a syringe consisting of a cylinder and a piston moving inside it, which can draw in a certain amount of fluid and dose it out to the desired destination. For manual dosage, the spring is a handy and accurate instrument, but its high cost limits its applicability in larger systems, partly or completely automated.

One of the devices currently used for the transfer and dosage of fluids is the peristaltic pump, which typically consists of a rotatable roller mounted against a cylindrical surface, and a flexible hose placed between the roller and the cylindrical surface, the fluid advancing in the hose. The cylindrical surface of' the roller is provided with protrusions placed at equal distance from each other, the hose being squeezed flat by each protrusion, so that the fluid in the hose is divided into doses of a certain volume between the protrusions. As the roller rotates, the doses of fluid are pushed forward in the hose by the protrusions. The disadvantages 2 of the device are its inaccuracy and a slight fluctuation of the fluid flow, which arises from the slight reverse rushes of the fluid occuring each time when a protrusion is disengaged from contact with the hose.

In another dosing procedure, the fluid is passed via thin pipes into a space of given size, in which a dose of the fluid is entrapped by freezing the pipes at certain points at both ends of the dosage space. This solution, which is described in the F1 patent publication 57850 is designed for use in an analyzing device which exclusively employs this kind of freezing taps to control the fluid flow. The solution is impractical for use in simple measuring and analyzing equipment.

The object of the present invention is to produce a simple solution for the dosage of flowing substances whi ch can be widely applied in various systems especially for the dosage of fluids but also of gases. The invention is characterised in that the substance is introduced into a system of branched pipes where it proceeds through the inlet branch to a branching point where two or more extension branches meet, that the fluid is allowed to flow past the branching point into one of the extensions, that the flow is stopped and that the fraction of substance which has entered the extension branch is separated from the fraction remaining the inlet branch by 3 letting an auxiliary substance flow in through one of these branches or a second extension branch, said auxiliary substance being of a kind that will not mix with the substance to be dosed, so that one of the fractions is carried away by the flow of the auxiliary substance, the two fractions being separated by a boundary surface appearing at the branching point.

The basic idea of the invention is to make use of the surface tension between the substance to be dosed and the auxiliary substance immiscible with it. As the branches of the system of pipes, at least in the region of the juncture, are of capillary dimensions, the surface tension between the immiscible substances creates a boundary surface at the branching point, a boundary surface of the same form being always produced at the same point in the pipe. This explains the precision of dosage achieved by the invention.

The chief area of publication of the invention are instruments for chemical wet analyses involving the dosage of a fluid, usually a water solution. The auxiliary substance immiscible with the fluid may be a gas, e.g. air, or another fluid immiscible with water, e.g. oil or a similar organic fluid.

A preferred embodiment of the procedure of the invention is characterised in that the substance to be dosed is directed into a system of branched pipes where 4 it proceeds through an inlet branch having a given dosage volume to a branching point where two or more extension branches meet, that the substance is allowed to flow past the branching point into one of the extensions, that the flow is interrupted so as to prevent backward flow of the substance in the inlet branch, and that the fraction of the substance which has entered the extension branch is removed by letting an auxiliary substance immiscible with the substance to be dosed flow in through one of the is carried away by the flow of the auxiliary substance, so that the boundary surface of the fraction remaining in the inlet branch is located at the branching point at the end of the inlet branch. One of the extension branches of the piping system may be provided with a pump which both draws in the substance to be dosed through the inlet branch and, by pumping the auxiliary substance in the opposite direction, removes the fraction of the substance which has proceeded past the branching point into the extension.

Another preferred embodiment of the procedure of the invention is characterised in that it uses a system of branched pipes in which the inlet branch bifurcates at a juncture into a lateral branch and a main branch, to which another lateral pipe is connected at a second juncture, that an auxiliary substance immiscible with the substance.

to be dosed is first introduced at least into the two lateral pipes that the su bstance to be dosed is then introduced into the inlet and main branch of the piping system in such manner that at least that part of the main branch which is delimited by the junctures of the two lateral branches is filled with said substance, boundary surfaces being formed at the junctures between the substance to be dosed and the auxiliary substance present in the lateral branches, that the flow of the substance to be dosed is blocked both in the inlet branch at a point before the first juncture and in the main branch at a point after the second juncture, and that finally the auxiliary substance is caused to flow through the lateral branches so as to remove the portion of substance contained in the main branch between the boundary surface at the two junctures of the two lateral branches thus constitutes the space of a definite volume in which the dose is formed.

The invention also relates to an apparatus for the application of the dosing procedure described above. The apparatus comprises as its essential parts a system of branched pipes consisting of' an inlet branch and one or more lateral or extension branches connected to the inlet branch or its extension at one or more junctures, and the requisite means for the arrangement of the desired flow of the substance to be dosed and the auxiliary substance in the pipes. Detailed characteristics of the apparatus 6 are presented in the claims below (7-10).

As stated before, the invention is suited for application in devices for wet chemical analyses. Such devices include analysers used in clinical and immunological chemistry to produce medical diagne-cs of specimens of substance, such as blo.i or urine, taken from a patient. Moreover, the -,, !,-,aratus can be used for the chemical analysis of -amples, chiefly of water, taken from the en-,-4i-nnment in the following, the invention is described in greater detail by the aid of examples, referring to the drawings attached, wherein:

Figs 1-5 represent different stages of a fluid manipulation process involving dosage of the fluid as provided by the invention.

Figs 6-7 represent two different varieties of a juncture of pipes as used in the dosing apparatus of the invention.

Figs 8-10 represent different stages of a second embodiment of the dosing procedure of the invention.

Figs 11-14 represents different stages of a third embodiment of the dosing procedure of the invention.

Figs 15-17 represent different stages of a fourth embodiment of the dosing procedure of the invention, in which the inlet branch of the piping s',vstem branches out into five extension branches at the same juncture.

Figures 1-5 represent a process in which the 1.

R 7 procedure of the in.vention is applied to separate from a liquid reagent a dose of a definite volume, which is mixed with a specimen in a sample cell and then transferred into a photometer for a measurement. The apparatus use consists of a system of branched pipes in which the inlet pipe 1 branches out into two extensions 3,4 at a T-shaped juncture 2. Branch 3, which is a direct extension of the inlet pipe 1, is provided with a pump 5, and the other, perpendicular extension branch 4 is provided with a valve 6. The inlet branch 1 is likewise provided with a valve 7. Before the juncture 2, the inlet pipe 1 branch out into two lateral branches 8, 9 one of which leads to the sample cell 10 and the other to the photometer 11. Each lateral branch 8,9 is provided with a valve 12,13.

Figure 1 shows an initial situation where a fluid reagent has been sucked by the pump 5 via the inlet branch I into the system so that the column of fluid in the pipe has proceeded past the juncture 2 as far as the point indicated by reference number 16. During the suction phase, the valve 7 in the inlet branch 1 is opean while the other valves 6,12,13 are closed. In the situation shown in figure 1, the suction is interrupted and the valve 7 in the inlet branch closed. Next, the 6 in the extension is opened and, as shown in %,alve figure 2, air is blown by the pump 5 - rotated in the reverse direction - through the extension branches 3,4 so 8 that the current of air carries away the fluid fraction 15 which has proceeded past the juncture 2 during the suction phase. The boundary surface of the column of fluid in the inlet pipe now settles exactly at the end of the inlet branch 1 at the juncture 2. Thus, a dose of fluid of a definite volume has been entrapped in the inlet branch 1.

Further, as shown in figure 2, the sample cell 10 contains the specimen 16 of a fluid or a solid substance to be diatsnosed. Figure 3 shows the next stage, where the valve 6 in the extension branch 4 is closed, the valve 12 in the lateral branch 8 leading to the sample cell 10 is open and the dose of reagent which was entrapped in the inlet branch 1 has been pushed up into the sample cell by a flow of air produced by the pump 5. The specimen in the sample cell 10 is preferably allowed to dissolve in the reagent to produce a solution 17 which is then diagnosed. As shown in fi%ure 4, the solution is sucked by the i-lump 5 back into the inlet pipe 1 and its direct extenpion 3 so that the sample cell 10 and the lateral branch 8 leading_ to it are emptied. When the column of fluid in the pipe extends as far as point 18, the suction is interrupted, vhereupon the valve 12 in the lateral branch 8 leading- to the sample cell 10 is closed, the valve 13 in the lateral branch- 9 leading to the photometer 11 is opened and, as shown in figure 5, the solution is pushed 9;- 1 9 by the pump 5 into the photometer for a measurement. After the measurement, the solution is exhausted into an extension of the lateral branch 9.

Figures 6 & 7 show two alternative types of juncture 2 for the connection of the pipes. In each case, the fluid to be dosed fills the inlet branch 1 in such manner that the boundary surface 19 appears exactly at the end of the inlet branch at the juncture 2.

In the embodiment illustrated by figures 8-10, the dosing equipment consists of a system of branched pipes in an H-shape general arrangement, in which the inlet pipe 20 bifurcates at the first juncture 21 into a main branch 22, which is placed at an angle of 900 relative to the inlet branch 20, and a lateral branch 23 constituting a direct extension of the inlet branch 20. The main branch 22 has another juncture 24, at which the main branch itself bends into an angle of 900 (the part of the main branch beyond the juncture is indicated by reference number 25) and connects to another lateral branch 26, also placed at an angle of 900. The inlet branch 20 and the first lateral branch 23 are provided with pumps 27,28 and each one of the four branches 20,23,25,26 is provided with a valve 29-32.

In this dosing process, the substance to be dosed is a fluid and the auxiliary substance is another fluid which is so selected that the two fluids are immiscible. In the initial situation shown in figure 8, the whole system is filled with the auxiliary fluid, which is pumped i n by the pumps 27,28, whereupon teh valves in the lateral branches 23,26 are closed. Next, as shown in figure 9 with the valves 29,32 open and using the pump 27, the inlet branch 20 and the main branch 22,25 are filled with the substance to be dosed, exact boundary surface 33,34 being now formed between the substance to be dosed junctures the valve the valve and the auxiliary substance at the pipe 21,24. After the pumping has been finished and 29, 32 in the inlet and main branches closed, 30,31 in the lateral branches 23,26 are opened and, as shown in figure 10 the pump 28 in the lateral branch 23 is used to produce a flow of auxiliary fluid which carries away the fraction of the substance to be dosed which was entrapped in the main branch between the two junctures. The dose thus obtained and flowing with the auxiliary fluid is indicated by reference number 37 in figure 10.

Figures 11-14 represent an embodiment in which the dosing operation is temporally or locally removed, using the dosing principle of the invention. The system of pipes, consisting of a main branch 39 and an inlet branch connected to it at the juncture 40 (the part of the main branch beyond the juncture being indicated by reference number 42) is connected to a dosing device 38 capable of sufficient precision, e.g. a syringe. Each branch is 0 11 provided with a valve 43,44 and connected to a pump or a similar device (not shown).

In the initial situation shown in figure 11, some of the fluid to be dosed has been sucked through the inlet branch 41 into the main branch 43 in such manner that the fluid flow has turned at the juncture 40 in the direction away from the dosing device 38. At the end of this suction phose, the valve 44 in the inlet branch is closed, whereupon, as shown in figure 12, using the dosing device 38, another fluid, which in this case acts as an auxiliary fluid, is sucked into the main branch 39,42. The flow of the auxiliary fluid now carries away the fraction of the fluid to be dosed which has entered the main branch 42, so that boundary surface between the two fluids appears at the end of the inlet branch 41 at the juncture 40. Next, the valve 43 in the main branch is closed and te valve 44 in the inlet branch opened, whereupon a certain amount of the auxiliary fluid is dosed by the dosing device 38, so that, as shown in figure 13 an equal amount of the fluid to be dosed flows at the same time through the inlet branch 41 past the juncture into the main branch 39. The la.tter dose of fluid can now be directed to the desired destination useing the dosing device, which pushes the dose out by pumping the auxiliary fluid through the main branch 39,42. Figure 14 shows a stiuation where the valve 44 in 1 12 the inlet branch is closed and a dose 46 of fluid is being pushed by the auxiliary fluid through the main branch 39 towards the dosing device 38.

Figures 15-17 show a set of pipes designed to be used in a further emobodiment of the invention. In this case, the inlet branch 47 is connected at a juncture 48 to five extension branches 49-53, each of which is provided with a valve 54.

In the initial situation shown in figure 15, each one of the branches contains a different liquid substance. The inlet branch 47 contains the substance to be dosed, which is flowing past the juncture 48 directly into the extension 51, where the flow is stopped e.g. by closing the valve 54 in this branch. The purpose of this operation is to ensure that the inlet junctur 48 is filled with the liquid to this, as shown in figure 16, the valve 54 extension branch 52 is onened and a pipe up to the be dosed. After in the adjacent certain amount certain of liquid to be dosed is caused to flow into this extension. The inlet branch 47 may be connected e.g. to a dosing syringe, in which case this solution constitutes a removed dosing operation similar to that in the embodiment represented by figures 11-14. After the flow of the substance to be dosed has stopped, the valve 54 in the inlet branch 47 is closed, whereupon the dose in the extension branch 52 can be moved further by means of W z 1 13 another liquid obta.ined from a different extension and acting as an auxiliary substance. Figure 17 shows a situation where the dose 55 is being removed from extension 52 by the flow of auxiliary substance proceeding from extension 50.

Regarding the dosing apparatus represented by figures 15-17, it is to be noted that, in principle, any one of the extension branches 49-53 connected to the juncture 48 can be selected as the inlet branch, in which case the substance to be dosed is the substance contained in the branch selected. This solution is viable subject only to the condition that the substance to be dosed be immiscible with the substance serving as an auxiliary substance.

Claims

14 CLAIMS

1. Procedure for the dosage of a flowing substance, characterised in that the substance is introduced into a system of branched pipes, where it proceeds through an inlet branch to a juncture which connects to two or more extension branches that the flow is allowed to proceed past the juncture into one of the extensions that the flow is stopped and that the fraction of substance which has entered the extension branch is separated from the fraction remaining in the inlet branch by letting an auxiliary substance flow in through one of' said branches or a second extension branch said auxiliary substance being immiscible with the substance to be dosed, so that one of the fractions is carried away by the flow of the auxiliary substance, the two fractions being separated by a boundary surface appearing at the juncture of the pipe branches.

2., Procedure according to claim 1, characterised in that the substance to be dosed is a liquid and that the auxiliary substance is a gas.

3. Procedure according to claim 1, characterised in that the substance to be dosed and the auxiliary substance are immiscible-liquids.

4. Procedure according to one of the claims 1-3, characterised in that the substance to be dosed is directed into a system of branched pipes where it proceeds through an inlet branch having a given dosage A volume to a juncture which connect to two or more extension branches, that the substance is allowed to flow past the juncture into one of the extensions, that the flow is interrupted so as to prevent backward flow of the substance in the inlet branch, and that the fraction of the substance which has entered the extension branch i reifioved by letting an auxiliary substance immiscible with the substance to be dosed flow in through one of the extension branch in such manner that the said fraction is carried away by the flow of the auxiliary substance, so that the boundary surface of the fraction remaining in the inlet branch is located at the juncture at the end of the inlet branch.

5. Procedure according to claim 4, characterised in that the substance to be dosed is sucked into the system of pipes using a pump placed in one of the extension branches and that the same pump is used to remove the fraction of substance that has proceeded from the inlet branch past the juncture into the extension concerned, by running the pump in a direction reversed to that used for suction.

6. Procedure according to one of the claims 1-3, characterised in that it uses a system of branched pipes in which the inlet branch bifurcates at a juncture into a main branch and a lateral branch and in which the main branch is further connected at a second juncture to C 16 another lateral branch, that an auxiliary substance immiscible with the substance to be dosed is first introduced at least into the two lateral branches, that the substance to be dosed is then caused to flow into the inlet and main branches of the system in such manner that a least that part of the main branch which is delimited by the junctures of the two lateral branches is filled with said substance, boundary surface being formed at the junctures between the substance to be dosed and the auxiliary substance present in the lateral branches, that the flow of the substance to be dosed is blocked both in the inlet branch at a point before th first juncture and in the main branch at a point after the second juncture, and that finally the auxiliary substance is caused to flow through the lateral branches so as to remove the portion of substance contained in the main branch between the boundary surfaces at the two junctures.

7. Apparatus for. implementing the procedure of claim 4 or 5, characterised in that the apparatus consists of a s--,-stem of branched pipes comprising an inlet branch of a definite dosage volume which is delimited at one end by a juncture connecting to one or more extension branches, and means for introducing the substance to be dosed into the system of pipes in such manner that the substance will flow past the said juncture, and for removing - by causing an auxiliary substnace immiscible with the 17 substance to be dosed flow through the extension branches the fraction of substance which h-as proceeded past the juncture into an extension branch, and that the inlet branch is provided with at least one valve to prevent reverse flow of the substnace to be dosed in the inlet branch during the removal of the said fraction.

8. Apparatus according to claim 7, characterised in that the apparatus comprises a pump placed in one of the extension branches of the system of pipes in such manner that the pump can be used for both drawing the substance to be dosed into the pipe and for removing the fraction of substance which has proceeded past the juncture into the extension concerned.

9. Apparatus for implementing the procedure of claim 6, characterised in that the apparatus consists of a system of branched pipes in which the inlet branch brifurcates at a juncture into a main branch and a lateral branch and in which the main branch is further connected to ann+her lateral branch, at a second juncture mean- for introducing an auxiliary substance ir-iscible with the substance to be dosed at least i-to the lateral branches of the system and means -Por introducing the substance to be dosed at)--qt into the inlet branch of the system and further in+o the main branch in such manner that at least the part of the main branch delimited by the two junctures is filled with said substance, and that valves 18 are provided in the inlet branch before the f irst juncture and in the main branch after the second juncture to prevent the flow of the substance to be dosed in these branches so as to enable the dose of the substance entrapped between the two junctures to be removed by the flow of an auxiliary substance passing through the lateral branches.

10. Apparatus according to one of the claims 7-9, characterised in that the pipe branches have a reduced diameter in the region of the juncture.

11. Apparatus according to one of' the claims 7-10, characterised in that it constitutes part of an analyzing device used for wet chemical analyses, particularly a clinical analyser.

12. A method of substantially dispensing a flowable substnace as described herein with reference to any one or more of the fi5ures. 1 R. Apparatus for dispensing a flowable substance -,ubstantially as described herein with reference to any one or more of the figures.

Published 1989 at The Patent Office, State House, 66-71 High Holborn, London WC1R 4Tp. Further copies maybe obtained from The Patent OfficeSales Branch, St Mary Cray, Orpington, Rent BR,5 3P.D. Printed by Multiplex techniques ltd, St Mary Cray, Rent, Con. 1/87 1