WO2000041550A2

WO2000041550A2 - Apparatus for measuring and delivery of small volumes of fluid

Info

Publication number: WO2000041550A2
Application number: PCT/ZA2000/000009
Authority: WO
Inventors: Peter Thebock; John William Hunt; Salim Essack
Original assignee: WAHOO TRUST
Current assignee: WAHOO TRUST
Priority date: 1999-01-18
Filing date: 2000-01-18
Publication date: 2000-07-20
Anticipated expiration: 2001-07-18
Also published as: WO2000041550A3; AU3128900A

Abstract

Apparatus is provided for measuring, or delivering predetermined small volumes of fluid. One or more bulbs are provided which have at least one membrane and also have an inlet for fluid and an outlet on one side of the membrane, and a connection to a source of air or other fluid under pressure on the other side of the membrane. The fluid to be measured or delivered is introduced through the inlet at a higher pressure than that holding the membrane in position. The membrane takes up the shape of the bulb and the inlet is closed. Pressure is applied to the membrane thus forcing the fluid through the outlet until the membrane has taken up the configuration of the bulb.

Description

-I -

APPARATUS FOR MEASURING, MIXING AND DELIVERY OF SMALL

VOLUMES OF FLUID

TECHNICAL FIELD OF THE INVENTION

This invention relates to apparatus for measuring, mixing and/or delivering small volumes of fluid.

BACKGROUND OF THE INVENTION

The measurement and delivery of small volumes of fluid for sampling and for the mixing of small volumes for many purposes, is well known. However, to the knowledge of the Applicant, known apparatus involves high cost- components which are very complicated.

It is an object of the present invention to provide apparatus which is very simple and inexpensive and which nevertheless delivers exact predetermined volumes.

DISCLOSURE OF THE INVENTION

According to the invention apparatus for measuring and/or delivering predetermined volumes of fluid includes a bulb or other container which includes a membrane with an inlet for fluid and an outlet on one side of the membrane and a connection to a source of air or other fluid under pressure on the other side of the membrane.

The source of air or other fluid (e.g. oil) is preferably maintained at a static pressure.

In operation the fluid to be dispensed is introduced into the inlet at a higher pressure than the pressure holding the membrane in position and the fluid is allowed to fill the bulb. The membrane then takes the shape of the other side of the cavity. The inlet is then closed by a valve and pressure is applied to the membrane thereby urging fluid through the outlet until the membrane has taken up the configuration of the bulb thus causing complete emptying of the bulb.

The valve may include a passageway for the fluid with an opening in the wall of the passageway which is obturatable by means of a membrane in association with the opening, pressure means being adapted to urge the member to the opening and to form a dimple through the opening to close the passageway when required.

In one form of the invention a plurality of bulbs may be provided each of predetermined volume depending on the nature of the operation. The bulbs may be joined by a hydraulic system manifold and each bulb is connected by its inlet to the pertinent supplies of fluids to be measured and/or delivered.

In a refinement of the invention a first bulb is filled with a predetermined mixture of fluids and this mixture is transferred to a second bulb of predetermined volume. During the transferring operation the membrane of the second bulb may be flexed by alternately pressurizing and depressurizing the space below the membrane until a predetermined quantity of the mixed mixture can be forced through the outlet.

The apparatus of the invention may be used for mixing paint formulations containing predetermined quantities of analyzable substances used for application to motor vehicles or to any articles required to be "labelled" for identification purposes.

In another form of the invention, each bulb includes at least one membrane which is permeable to a chosen substance in solution or suspension in the fluid.

The solute which is micro filtered through the membrane can be dispensed separately from the solvent or partly micro filtered solution or suspension. This solute may for example be introduced into a further bulb to provide it with a predetermined volume of the solute. This allows for chemical or biological or other reaction to take place for further dispersion to take place in any other mixing chamber in exact volumes. Any bulb system may be used for volumetrically exact analytical and synthetic or pure mixing and separation operations and/or operation sequences or sets of them.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below with reference to the accompanying sketches in which:

Figure 1 is a diagrammatic front view of a bank of measuring and delivery bulbs;

Figure 2 is a similar view of an alternate form of apparatus;

Figure 3 is a diagrammatic view of a bulb having a permeable member for micro filtration of a solution or suspension, as well as a non-permeable member; Figure 4 is a view similar to Figure 3 showing an alternative form;

Figure 5 is another similar view of a pair of intercommunicating bulbs;

Figure 6 is a sectional plan view of a unit comprising four bulbs in a particular configuration;

Figure 7 is a cross sectional view on the line X-X of Figure 6; Figure 8 is a sectional side view of an alternative unit to Figure 6 and 7. and

Figure 9 is a cross sectional view on the line X-X of Figure 8.

DESCRIPTION OF MODES OF THE INVENTION

In Figure 1 a bank of four containers 10 is provided. Each container may have a different fluid or concentration of substance in solution or in suspension.

The containers are connected to a bank of bulbs 12 which may have the same or different volumes depending on the final mixture required.

Each bulb has a valved inlet 14 and valved outlet 16. A latex membrane 18 is located across the bulbs and the space 20 thcrebelow is connected to a static hydraulic system manifold 22. The membrane may be drawn by vacuum to conform with the interior of the bulb and fluid from the containers is drawn into the inlets until the bulbs are full. The inlet valves are then closed and pressure is applied below the membranes causing them to conform to the upper interior of the bulbs and thereby force all of the fluids through the outlets 16.

The fluids may comprise lanthanide solutions in chosen solvents for incorporation into a paint for a vehicle so that the vehicle is "labelled" with a chemical code for identification by X-ray or other analysis.

In Figure 2 a bulb 30 has a plurality of valved inlets 32 and a outlet 34. Predetermined fluids or predetermined volumes of chosen fluids are introduced into the bulb 30 to a full state by causing a vacuum or hydraulic pressure under a latex membrane 36. When full the inlets are closed and the outlet is opened, pressure is applied under the membrane whose deformation causes complete expulsion of the unmixed mixture into bulb 40. During the filling of bulb 40, its membrane 42 may be flexed alternately by increasing and decreasing the hydraulic pressure below, thereby causing mixing. When fully mixed and filled, the outlet 44 is opened and the mixture transferred to its required location, by closing all valves 32 by pressurizing membrane 36; and then pressurizing membrane 42.

Turning now to Figure 3, the bulb 50 has a non-permeable membrane 52 and a permeable membrane 54 for a desired chemical. Oil at a static pressure is introduced through inlet 58 while a chosen gas is introduced through inlet 60. A liquid is introduced through inlet 62 at pressure higher than the static pressure υf the oil. The oil is then moved to and fro with the result that a gas-liquid mixture of exact predetermined concentration is forced through outlet 66 when desired.

In Figure 4, the gas is introduced into a permeable bubble membrane 70. The operation is virtually the same, with oil being introduced through inlet 58, gas being introduced through inlet 72 into the membrane 70, with the liquid being introduced through inlet 74. The solution of predetermined concentration is exited through outlet 76. In Figure 5 bulbs 80, 82 include a connecting T-piece 84 provided with a valve 86. The bulbs have membranes 88 held in gaskets 90.

Each bulb also has an inlet 92 for oil at static pressure during filling of the bulbs, for dynamic pressure during the mixing operation and return to static pressure on release of the predetermined solution through the valve 86.

A substance or mixture is introduced into the chamber 100 through inlet 102. the inlet 104 being connected to oil at a static pressure. The chemical exits through the outlet 106, and through valve 108 (see Figure 6) into the bulb 80. Valve 108 includes a passageway 110 which has an opening 1 12 in its wall. A membrane 1 13 is housed in the domed portion 1 14 of the seating, the membrane being supported by a ring 1 16. The application of pressure below the membrane causes it to assume the domed shape of the domed portion 1 14 and the apex of the membrane includes a portion 1 18 which extends through the opening 1 12 at a predetermined pressure, assuming the shape of a nipple or dimple to seal the passageway.

In Figures 6 and 7 a unit comprising a nest of four bulbs 100 is provided with the valves indicated by the same references as used above. The bulbs are arranged in a housing 122 and encased in capsules 124.

In Figures 8 and 9 the bulbs 100 are arranged peripherally on a casing 132.

The invention extends to these and similar nest units having any reasonable number of bulbs.

It will be appreciated that the apparatus of the invention can be used to provide exact predetermined volumes of substances which can be mixed or reacted in different vessels at exact pressures.

Using dedicated sets of permeable membranes one can achieve any of the following scenarios: A solution of a gas A and gas B in a solvent C. If the hydrostatic pressure of the system is increased by use of the non-permeable membrane, as described above, the temperature may be adjusted until a desired phase separation occurs. The gas A phase is then released into the portion of the bulb dedicated by a membrane permeable only to gas A. Thus, gas B can be separated. Since the exact volumes are predetermined by the volume of the bulb, it is possible to determine volumetrically exact separations of multi-phase systems.

It is also possible to achieve volumetrically exact admixtures and/or solutions of multi-phase systems.

For example, a unit volume of a gauged solution mav be introduced into a bulb which is then pressurized until the desired phase separation is achieved due to the effect of the hydrostatic pressure via the non-permeable membrane. This induces diffusion of solute via the permeable membrane into the solvent on the other side of the same membrane.

Electro membranes may be used to effect ion exchange reactions.

A measurable electropotential is generated by concentration (activity) differences at opposite sides of the membrane, causing electromotive forces. The diffusing chemical species can be gaseous, ionic or even non-ionic in nature. The membrane itself can be on any material, preferably an elastic one.

If selective membrane electrodes are used one may be able to achieve quantitative on line measurements, for example equilibrium reactions and diffusion processes.

Dialysis processes may be easily effected.

Concentration driven processes are achievable using the apparatus of the invention.

Apart from micro filtration as described above other pressure driven processes such as ultra- and hyper- filtration processes are possible using selected membranes. Through the use of the volumetric chambers surrounding the membranes it is an advantage of the invention that one can precisely determine and monitor displaced volumes during the processes described and mentioned.

It will be clear to persons skilled in the art that the above are only examples of applications using the apparatus of the invention - for example viscosity measurements, volumetric determinations involving osmotic processes and the like, all of which fall within the ambit of the invention.

Claims

CLAIMS:

1. Apparatus for measuring and/or delivering predetermined volumes of fluid characterised in that it comprises a bulb or other container which includes at least one membrane with an inlet for fluid and an outlet on one side of the membrane and a connection to a source of air or other fluid under pressure on the other side of the membrane.

2. The apparatus according to claim 1 characterised in that the source of fluid is maintained at static pressure.

3. The apparatus according to claim 1 or claim 2 characterised in that, in operation, the fluid to be dispensed is introduced into the inlet at a higher pressure than the pressure holding the membrane in position and the fluid is allowed to fill the bulb, the membrane taking the shape of the other side of the cavity; the inlet then being closed by a valve and pressure is applied to the membrane thereby urging fluid through the outlet until the membrane has taken up the configuration of the bulb thus causing complete emptying of the bulb.

4. The apparatus according to claim 3 characterised in that the valve includes a passageway for the fluid with an opening in the wall of the passageway which is closeable by means of a membrane in association with the opening, pressure means being adapted to urge the membrane to the opening and to form a dimple through the opening to close the passageway when required.

5. The apparatus according to any of the above claims characterised in that a plurality of bulbs are provided each of predetermined volume depending on the nature of the operation.

6. The apparatus according to claim 5' characterised in that the bulbs are joined by a hydraulic system manifold and each bulb is connected by its inlet to the pertinent supplies of fluids to be measured and/or delivered.

7. The apparatus according to claim 5 characterised in that the bulbs are first filled with a predetermined mixture of fluids and this mixture is transferred to a second bulb of predetermined volume, during which transferring the membrane of the second bulb is flexed by alternately pressurizing and depressurizing the space below the membrane until a predetermined quantity of the mixed mixture can be forced through the outlet.

8. The apparatus according to any of the above claims characterised in that each bulb includes at least one membrane which is permeable to a chosen substance in solution or suspension in the fluid.

9. The apparatus according to claim 8 characterised in that the solute which is micro filtered through the permeable membrane is dispensed separately from the solvent or a partly micro filtered solution or suspension.

10. The apparatus according to claim 9 characterised in that the solute is introduced into a further bulb to provide it with a predetermined volume of the solute.

11. A nest unit including a plurality of apparatuses according to claim 1, arranged in a predetermined configuration.

12. A nest unit according to claim 1 1 characterised in that the apparatuses are arranged within a casing.

13. A nest unit according to claim 1 1 characterised in that the apparatuses are located peripherally on a casing.