DE102011003615B4 - Method and device for measuring a volume flow of a liquid flowing into a container and/or a volume of the liquid flowing into the container - Google Patents

Abstract

Device for measuring a volume flow (dV(t)/dt) of a liquid (A, B) flowing into a container (1) and/or a volume (V(t)) of the liquid (A, B) flowing into the container (1), with- a device connected to the container (1) which serves to enclose gas in a predetermined initial volume (Vo) in the interior of the container (1) before the liquid flows in under an initial pressure (po),- a pressure sensor (23) for measuring the gas pressure (pG) in the container (1),- a liquid supply device (5) connected to a filling opening (3) of the container (1) which opens into the interior of the container (1), which serves to supply liquid (A, B) to the container (1), wherein the container (1) comprises a plunger (51) which is movable in the interior of the container (1), lies liquid-tight and gas-tight against a container wall enclosing the interior, which plunger fills the container (1) into a liquid space (52), into which the filling opening (3) opens, and a gas space (53) which is connected to the device which serves to enclose gas in a predetermined initial volume (Vo) in the interior of the container (1) before the liquid flows in under an initial pressure (po), and to the pressure sensor (23), and- an electronic unit (25),-- which determines the volume (V(t)) of the inflowing liquid and/or the volume flow (dV(t)/dt) of the inflowing liquid on the basis of the gas pressure (pG) measured by the pressure sensor (23) after the container (1) filled with the initial volume (Vo) of gas under the initial pressure (po) has been closed.

Description

The invention relates to a method for measuring a volume flow of a liquid flowing into a container and/or a volume of the liquid flowing into the container, as well as a device for carrying out this method.

The invention can be used in all areas of industrial measurement technology, medicine and laboratory technology in which liquids are transported or dosed in a controlled manner, in particular with the help of microfluidic systems or in the field of micro process engineering. This is particularly the case in the area of liquid analysis. Examples of this are analysis systems for monitoring and optimizing the cleaning performance of sewage treatment plants, for drinking water monitoring, for monitoring biotechnological processes or for quality monitoring of liquids or foods used in industry. For example, the content of a liquid sample of substances, e.g. ions such as ammonium, phosphate or nitrate, of biological or biochemical compounds, e.g. hormones, or of microorganisms, e.g. bacteria, are measured and monitored.

In such systems, in addition to the liquid to be analyzed, it is also necessary to dose additional liquids required for its analysis, such as reagent solutions, in predetermined quantities, to mix predetermined target volumes of different liquids if necessary, and/or to generate predetermined target volume flows of liquids through lines or measuring and/or analysis units.

In order to achieve the highest possible level of automation, particularly in the area of analysis, devices and methods are required by which the generally very small target volumes of less than 50 mL, especially less than 10 mL, required in miniaturized systems can be dosed, and by which the low volume flows of less than 5000 µL/min, especially less than 1000 µL/min, of the liquids through the individual systems can be regulated to target volume flows specified depending on the process or procedure to be carried out.

Peristaltic pumps, for example, are used today to transport these liquids. However, due to the way they work, peristaltic pumps usually produce pulsating volume flows. In addition, the elastic hoses used in conjunction with peristaltic pumps are subject to aging, which affects the delivery capacity of the peristaltic pumps. This limits the accuracy with which specified target volumes of a liquid can be filled or specified target volume flows can be generated.

Another frequently used variant for transporting liquids is syringe pumps. These are characterized by high precision and consistent flow properties. However, the use of syringe pumps in automated systems is hampered by their high price and low robustness.

Volume flows can be achieved in a simple manner using pneumatic devices in which liquid flows are caused by pressurizing the liquid provided in a storage container with a gas, especially air. Typically, however, the flow resistance of these systems changes over time, e.g. due to the increasing emptying of the storage container, so that regulation of the volume flow through the system is necessary.

For this purpose, the volume flow can be measured, for example, by means of flow sensors integrated into the fluid system, as used, for example, in the WO 2007/147786 A1 However, these sensors are expensive and come into direct contact with the liquid. The latter carries the risk of contamination of both the sensor and the liquid.

The documents EN 10 2010 030 790 A1 , DE 101 10 649 A1 , AT 508 276 A1 , DE 37 19 551 A1 , EN 10 2005 023 410 A1 , EN 11 2008 001 686 T5 , US 4 840 064 A and DE 196 54 829 A1 deal with the measurement of volume flows or liquid volumes.

It is an object of the invention to provide a device for measuring a volume flow of a liquid flowing into a container and/or a volume of the liquid flowing into the container, with which a high degree of automation can be achieved, particularly in microfluidic systems and in particular in the field of analysis.

• - einer an den Behälter angeschlossenen Vorrichtung, die dazu dient, Gas in einem vorgegebenen Ausgangsvolumen im Innenraum des Behälters vor dem Einströmen der Flüssigkeit unter einem Ausgangsdruck einzuschließen,
• - einem Drucksensor zur Messung des Gasdrucks im Behälter,
• - einer an eine in den Innenraum des Behälter mündende Befüllöffnung des Behälters angeschlossene Flüssigkeitszufuhreinrichtung, die dazu dient dem Behälter Flüssigkeit zuzuführen, und
• - einer elektronischen Einheit,
  • -- die anhand des nach dem Verschließen des unter dem Ausgangsdruck mit dem Ausgangsvolumen an Gas befüllten Behälters mit dem Drucksensor gemessenen Gasdrucks das Volumen der eingeströmten Flüssigkeit und/oder den Volumenstrom der einströmenden Flüssigkeit bestimmt.

The invention comprises a device with

• - a device connected to the container, which serves to enclose gas in a predetermined initial volume in the interior of the container before the liquid flows in under an initial pressure,
• - a pressure sensor to measure the gas pressure in the container,
• - a liquid supply device connected to a filling opening of the container which opens into the interior of the container and which serves to supply liquid to the container, and
• - an electronic unit,
  • -- which determines the volume of the inflowing liquid and/or the volume flow of the inflowing liquid on the basis of the gas pressure measured by the pressure sensor after the container filled with the initial volume of gas under the initial pressure has been closed.

According to the invention, the container comprises a plunger which is movable in the interior of the container and which rests liquid- and gas-tight against a container wall enclosing the interior, which divides the container into a liquid space into which the filling opening opens, and a gas space which is connected to the device which serves to enclose gas in a predetermined initial volume in the interior of the container before the liquid flows in under an initial pressure, and to the pressure sensor.

• - vor dem Einströmen der Flüssigkeit in einem vorgegebenen Ausgangsvolumen im Behälter ein Gas unter einem Ausgangsdruck eingeschlossen wird,
• - die anschließend in den Behälter einströmende Flüssigkeit das eingeschlossene Gas auf ein von dem Volumen der eingeströmten Flüssigkeit abhängiges Gasvolumen komprimiert, und einen vom eingeströmten Volumen und vom einströmenden Volumenstrom abhängigen Anstieg des Gasdrucks des Gases im Behälter gegenüber dem Ausgangsdruck bewirkt,
• - der Gasdruck im Behälter als Funktion der Zeit gemessen wird, und
• - das bis zur Zeit eingeströmte Volumen und/oder der zur Zeit einströmende Volumenstrom anhand des gemessenen Gasdrucks bestimmt wird.

By means of the device according to the invention, a method for measuring a volume flow of a liquid flowing into a container and/or a volume of the liquid flowing into the container can be carried out, in which

• - before the liquid flows into the container, a gas is enclosed under an initial pressure in a predetermined initial volume,
• - the liquid subsequently flowing into the container compresses the enclosed gas to a gas volume that depends on the volume of the liquid flowing in, and causes an increase in the gas pressure of the gas in the container compared to the initial pressure that depends on the volume flowing in and the incoming volume flow,
• - the gas pressure in the container is measured as a function of time, and
• - the volume flowing in up to the time and/or the volume flow currently flowing in is determined on the basis of the measured gas pressure.

The volume that has flowed in up to that time is determined based on the gas pressure measured at that time.

To determine the volume flow, the electronic unit is used to determine a temporal change in the measured gas pressure, and the volume flow currently flowing into the container is determined based on the temporal change in the measured gas pressure.

• - ein relativer Gasdruck definiert, der gleich einem Quotienten aus dem Ausgangsdruck und dem Gasdruck ist,
• - eine Kenngröße bestimmt, die die Steigung des relativen Gasdrucks in Abhängigkeit vom eingeströmten Volumen angibt,
• - während des Einströmens der Flüssigkeit in den Behälter anhand des als Funktion der Zeit gemessenen Gasdrucks der relative Gasdruck als Funktion der Zeit bestimmt, und
• - das Volumen und/oder der Volumenstrom werden anhand des relativen Gasdrucks bestimmt.

According to a further training, the electronic unit

• - a relative gas pressure is defined which is equal to a quotient of the initial pressure and the gas pressure,
• - a parameter is determined which indicates the gradient of the relative gas pressure as a function of the inflowing volume,
• - during the flow of the liquid into the container, the relative gas pressure is determined as a function of time using the gas pressure measured as a function of time, and
• - the volume and/or the volume flow are determined based on the relative gas pressure.

The parameter is preferably determined in a preceding calibration procedure.

• - wird das bis zum Zeitpunkt eingeströmte Volumen als Quotient aus dem um 1 reduzierten relativen Gasdruck zur Zeit und der Kenngröße bestimmt, und/oder
• - es wird eine zeitliche Änderungsrate des relativen Gasdrucks bestimmt, und
• - der zur Zeit einströmende Volumenstrom als Quotient aus der zeitliche Änderungsrate des relativen Gasdrucks und der Kenngröße bestimmt wird.

According to a design of this training

• - the volume flowing in up to the time is determined as the quotient of the relative gas pressure at the time reduced by 1 and the characteristic value, and/or
• - a rate of change of the relative gas pressure is determined, and
• - the currently incoming volume flow is determined as the quotient of the rate of change of the relative gas pressure and the characteristic value.

According to a further development, the device comprises a control which controls the liquid supply effected by the liquid supply device as a function of the measured volume flowing into the container or the measured volume flow flowing into the container.

According to one embodiment, the controller stops the liquid supply when the measured volume reaches a predetermined target volume.

In one embodiment, the liquid supply device comprises at least one liquid-filled reservoir, in particular two liquid-filled reservoirs, and a device for causing a liquid flow from the reservoir, in particular the reservoirs, into the container,
wherein the at least one reservoir has a cavity in which the liquid is received, and in which a movable plunger is arranged which rests in a liquid-tight and gas-tight manner on an inner wall surrounding the cavity and divides the at least one reservoir into a liquid space which is connected to the container via at least one liquid line and a gas space which is operatively connected to the device for causing a liquid flow from the reservoir, in particular the reservoirs, into the container.

• - das Gas in dem vorgegebenen Ausgangsvolumen unter dem Ausgangsdruck eingeschlossen wird,
• - der Behälter über die Vorrichtung zur Bewirkung des Flüssigkeitsstromes sukzessiv mit vorgegebenen Sollvolumen von Flüssigkeiten aus zwei oder mehr verschiedenen Speichern befüllt wird,
• - wobei das Erreichen der jeweiligen Sollvolumina der einzelnen Flüssigkeiten anhand des gemessenen in den Behälter insgesamt eingeströmten Volumens und dem zu Beginn des jeweiligen Befüllvorgangs mit der jeweiligen Flüssigkeit aus dem jeweiligen Speicher bereits in dem Behälter befindlichen und mit der Vorrichtung gemessenen Volumen überwacht wird.

The invention further comprises a method which operates the device according to the invention, wherein the liquid supply device comprises at least two reservoirs filled with liquid and a device for causing a liquid flow from the reservoirs into the container, in which

• - the gas is enclosed in the specified initial volume under the initial pressure,
• - the container is successively filled with predetermined target volumes of liquids from two or more different reservoirs via the device for causing the liquid flow,
• - whereby the achievement of the respective target volumes of the individual liquids is monitored on the basis of the measured total volume flowing into the container and the volume already in the container at the start of the respective filling process with the respective liquid from the respective storage tank and measured with the device.

When successively filling the container with the different target volumes of the individual liquids, it is preferable to start filling with the liquid that requires the largest target volume and then continue filling successively with the liquid that requires the next smallest target volume.

• - die Flüssigkeitszufuhreinrichtung die Flüssigkeit durch eine Speiseleitung in den Behälter leitet,
• - ein Volumenstrom der Flüssigkeit durch die Speiseleitung gleich dem in den Behälter einströmenden Volumenstrom ist, und
• - eine Regeleinrichtung vorgesehen ist, die die durch die Flüssigkeitszufuhreinrichtung bewirkte Flüssigkeitszufuhr anhand des gemessenen in den Behälter einströmenden Volumenstroms derart regelt, dass der Volumenstrom durch die Speiseleitung und der Volumenstrom in den Behälter einem vorgegebenen Sollvolumenstrom entspricht.

The invention further comprises a further development of the device according to the invention, in which

• - the liquid supply device directs the liquid into the container through a feed line,
• - a volume flow of the liquid through the feed line is equal to the volume flow flowing into the container, and
• - a control device is provided which controls the liquid supply effected by the liquid supply device on the basis of the measured volume flow flowing into the container in such a way that the volume flow through the feed line and the volume flow into the container correspond to a predetermined target volume flow.

This control is particularly advantageous for the embodiments described above, in which the at least one reservoir or reservoirs and/or the container each comprise a movable piston which divides the container or reservoirs into a gas space and a liquid space. The force required to transport the liquids from the reservoirs into the containers on the pistons, which is brought about, for example, by pressurizing the gas spaces of the reservoirs, also depends on the respective frictional resistance of the pistons in the reservoirs or in the container. By controlling the liquid supply based on the recorded volume flow, different frictional resistances of the pistons are compensated by the control.

• - ist in die Speiseleitung eine Mess- oder Analyseeinrichtung eingesetzt,
• - ist ein Volumenstrom der Flüssigkeit durch die Mess- oder Analyseeinrichtung gleich dem Volumenstrom durch die Speiseleitung und gleich dem in den Behälter einströmenden Volumenstrom, und
• - die Regeleinrichtung regelt den Volumenstrom durch die Mess- oder Analyseeinrichtung anhand des gemessenen in den Behälter einströmenden Volumenstroms auf einen vorgegebenen Sollvolumenstrom.

According to a preferred embodiment

• - a measuring or analysis device is installed in the feed line,
• - a volume flow of the liquid through the measuring or analysis device is equal to the volume flow through the feed line and equal to the volume flow flowing into the container, and
• - the control device regulates the volume flow through the measuring or analysis device to a predetermined target volume flow based on the measured volume flow flowing into the container.

• - die Flüssigkeitszufuhreinrichtung mindestens einen mit Flüssigkeit gefüllten Speicher und eine Vorrichtung zur Bewirkung eines Flüssigkeitsstromes von mindestens einem der Speicher in den Behälter umfasst,
• - die Vorrichtung zur Bewirkung des Flüssigkeitsstromes einen regelbaren pneumatischen Druckgeber umfasst,
  • -- der jeweils über eine mit einem steuerbaren Ventil, insb. einem 3/2 Wege Umschaltventil, versehene Druckzuleitung an die Speicher angeschlossen ist, und
• - der Flüssigkeitsstrom durch eine Druckbeaufschlagung der Flüssigkeit in den Speichern mit einem von dem regelbaren pneumatischen Druckgeber erzeugten Druck bewirkt wird.

The invention further comprises a further development of the device according to the invention, in which

• - the liquid supply device comprises at least one reservoir filled with liquid and a device for causing a flow of liquid from at least one of the reservoirs into the container,
• - the device for causing the liquid flow comprises an adjustable pneumatic pressure sensor,
  • -- which is connected to the storage tanks via a pressure supply line equipped with a controllable valve, in particular a 3/2-way changeover valve, and
• - the liquid flow is caused by pressurising the liquid in the accumulators with a pressure generated by the adjustable pneumatic pressure sensor.

According to a first development of the latter development, the adjustable pneumatic pressure sensor is connected to the container via a pressure supply line that can be closed with a controllable valve, in particular a 3/2-way changeover valve.

According to a preferred development, the liquid supply device is connected to the container via at least one supply line equipped with a valve, in particular a check valve.

• - der Behälter und die Flüssigkeit in den Speichern vorab über die 3/2 Wege Umschaltventile mit dem Ausgangsdruck beaufschlagt werden,
• - das Ventil in der vom Druckgeber zum Behälter führenden Druckzuleitung geschlossen wird,
• - durch Druckbeaufschlagung von Flüssigkeit aus mindestens einem der Speicher mit einem von dem Druckgeber erzeugten Druck ein Flüssigkeitsstrom in den Behälter bewirkt wird, und
• - abschließend die insgesamt in dem jeweiligen Betriebszyklus in den Behälter eingeströmte Flüssigkeit, insb. durch Druckbeaufschlagung, aus dem Behälter abgeführt wird.

The invention further comprises a method which operates a device according to one of the last three developments,
in which operating cycles are carried out in which

• - the container and the liquid in the storage tanks are pre-pressurized with the outlet pressure via the 3/2 way changeover valves,
• - the valve in the pressure supply line leading from the pressure sensor to the container is closed,
• - by pressurising liquid from at least one of the reservoirs with a pressure generated by the pressure transmitter, a flow of liquid into the container is caused, and
• - finally, the total liquid that has flowed into the container during the respective operating cycle is discharged from the container, in particular by pressurization.

According to a further development of the first development of the device, the container is connected via a drain line equipped with a valve, in particular a check valve, to a receiving vessel which is subjected to ambient pressure via a vent opening and into which liquid in the container can be drained.

• - die Flüssigkeitszufuhr in den Behälter unterbrochen wird, und
• - die im Behälter enthaltene Flüssigkeit über den Druckgeber mit einem Druck beaufschlagt wird, bei dem die Flüssigkeit durch das Rückschlagventil hindurch über die Ablassleitung ausströmt.

The invention further comprises a method which operates a device according to the last-mentioned development and in which the liquid is drained from the container at the end of a filling cycle by

• - the liquid supply to the container is interrupted, and
• - the liquid contained in the container is subjected to a pressure via the pressure sensor at which the liquid flows out through the check valve via the drain line.

• - Gas in dem vorgegebenen Ausgangsvolumen unter dem Ausgangsdruck eingeschlossen wird,
• - ein Flüssigkeitsstrom in den Behälter bewirkt wird und der einströmende Volumenstrom und/oder das eingeströmte Volumen gemessen wird,
• - die Flüssigkeitszufuhr in den Behälter unterbrochen wird, bevor der Gasdruck im Behälter einen vorgegebenen Maximaldruck übersteigt, und
• - abschließend die in den Behälter in dem jeweiligen Befüllzyklus insgesamt eingeströmte Flüssigkeit aus dem Behälter abgeführt wird.

The invention further comprises a method which operates a device according to the invention and in which operating cycles are carried out in which

• - Gas is enclosed in the specified output volume under the output pressure,
• - a liquid flow is caused into the container and the inflowing volume flow and/or the inflowing volume is measured,
• - the liquid supply to the container is interrupted before the gas pressure in the container exceeds a predetermined maximum pressure, and
• - finally, the total liquid that has flowed into the container during the respective filling cycle is drained from the container.

The invention has the advantage that the device can be operated fully automatically. A further advantage is that the measurements are made indirectly based on the gas pressure in the container, so that no direct contact, in particular no direct contact of sensors, with the liquid is required. In addition, the invention offers the advantage that, due to the indirect measuring method on which the invention is based, the measurement is largely independent of the type of liquid used, in particular of its viscosities, its inhomogeneities and any contaminants it may contain. This is particularly an advantage over calorimetric flow measurement methods, in which the measurement accuracy depends largely on the possibly variable heat capacities of the liquids.
The devices according to the invention offer the advantage of being extremely versatile. They can be used to replace dosing syringes, syringe pumps, peristaltic pumps as well as systems that generate volume flows pneumatically and regulate these to predetermined target volume flows using direct flow measurements with flow sensors inserted in the flow path.

• 1 zeigt: eine erfindungsgemäße Vorrichtung; und
• 2 zeigt: einen Ausschnitt einer alternativen Ausgestaltung
• 3 zeigt: eine Variante der Vorrichtung gemäß 1.

The invention and further advantages are now explained in more detail with reference to the figures of the drawing, in which two embodiments are shown. Identical elements are provided with the same reference numerals in the figures.

• 1 shows: a device according to the invention; and
• 2 shows: a section of an alternative design
• 3 shows: a variant of the device according to 1 .

1 shows a device according to the invention for measuring a volume flow dV(t)/dt a liquid flowing into a container 1 and/or a volume V(t) of the liquid flowing into the container 1.

The device comprises a liquid supply device 5 connected to a filling opening 3 of the container 1 that opens into the interior of the container 1 and serves to supply liquid to the container 1. This comprises at least one reservoir 7, 9 filled with a liquid A, B in which liquid is provided. The reservoirs 7, 9 are, for example, storage containers that contain individual liquids to be analyzed or additional liquids required for analysis, such as reagent solutions. The liquids A, B can be contained in the reservoirs 7, 9, for example, in a flexible gas- and liquid-impermeable container, e.g. a bag made of a plastic film, for example made of polyethylene or polypropylene. The reservoirs 7, 9 are preferably designed as exchangeable modules. The reservoirs 7, 9 can be provided as individual elements, or two or more reservoirs can be combined in parallel to one another in a preferably exchangeable storage cartridge.

The accumulators 7, 9 are connected to a device for causing a liquid flow from at least one of the accumulators 7, 9 into the container 1. This device comprises a controllable pneumatic pressure transmitter 11, which is connected to the inlet side of the accumulators 7, 9 via a pressure supply line 13, 15 that can be closed with a controllable valve V1, V2. The valves V1, V2 are preferably 3/2-way changeover valves, via which the accumulators 7, 9 can be optionally pressurized with the pressure p generated by the pressure transmitter 11 or a reference pressure p _B , preferably the atmospheric pressure, or can be closed pressure-tight and gas-tight on the inlet side by completely closing the respective valve V1, V2. The terms 'open' and 'close' are used here in connection with all valves in such a way that the associated line into which the respective valve is inserted is free when the valve is open and blocked when the valve is closed.

On the output side, the accumulators 7, 9 are each connected to the filling opening 3 of the container 1 via a supply line 17, 19, in the end of which facing the container 1 a valve VR1, VR2, preferably a check valve, is inserted. In the embodiment shown, the two supply lines 17, 19 open into a supply line 20 which connects them to the filling opening 3.

If only one reservoir, e.g. reservoir 7, is provided, preferably a single reservoir is inserted directly in front of the filling opening 3 in the supply line 20 leading from the reservoir 7 to the filling opening 3 - in 1 additionally drawn valve VR is used. In this case, the valves in 1 shown second accumulator 9, its supply line 19 and the two valves VR1 and VR2.

The same applies to several storage tanks that are always used at the same time in parallel for filling, the liquids of which are brought together in a supply line 20 that leads directly to the container 1. The latter corresponds to the variant shown without the two valves VR1 and VR2 in the supply lines 17 and 19.

However, if two or more storage tanks 7, 9 are each connected to the tank 1 via their supply line 17, 19, each equipped with the corresponding valve VR1, VR2, e.g. via the additional supply line 20, the valve VR additionally shown here can be omitted.

Alternatively, the container 1 can have a separate filling opening for each of the supply lines connected to one of the storage tanks, to which the supply lines are each connected via a valve. This embodiment is shown in 2 shown section of an alternative embodiment of a device according to the invention. There, four reservoirs 7a, 7b, 7c, 7d are each connected via a connected supply line 17a, 17b, 17c, 17d to one of the four filling openings 3a, 3b, 3c, 3d of the container 1. Each of the four supply lines 17a, 17b, 17c, 17d is equipped on the container side with a valve VRa, VRb, VRc, VRd, preferably a passive check valve.

A liquid flow from one or several storages 7, 9 into the container 1 can be 1 The variant shown can now be brought about at any time by applying a pressure p to the liquid in the respective reservoir 7, 9 via the pressure sensor 11, which pressure p is far enough above the pressure prevailing inside the container 1 to overcome the breakthrough pressure of the respective check valve VR1, VR2 or VR and the flow resistance of the respective supply line 17, 19 and 20. As soon as the pressure falling via the respective check valve VR1, VR2 or VR is greater than its breakthrough pressure, a liquid flow flows from the respective reservoir 7 or 9 into the container 1, which increases with increasing pressure p generated by the pressure sensor 11. The liquid supply can be fully automatic via a corresponding control of the pressure sensor 11 and the valves V1, V2. In this case, depending on the measuring method according to the invention and the use of the device, liquid A, B is supplied to the container 1 at predetermined times from a selected reservoir, from several selected reservoirs, or from all reservoirs 7, 9, or the liquid supply is interrupted altogether.

In order to interrupt the liquid supply from one or more reservoirs 7, 9, the liquid A, B in the affected reservoirs 7, 9 is subjected to the reference pressure p _B , in particular the atmospheric pressure, preferably via a corresponding control of the respective 3/2-way changeover valve V1, V2 in the associated pressure supply line 13, 15. This ensures that the pressure drop across the respective check valve VR1, VR2 or VR drops immediately below the breakthrough pressure and no more liquid A, B can escape through the respective supply line 17, 19 or 20. Alternatively, when using active valves instead of the passive check valves VR1, VR2, the liquid supply can also be controlled by actively opening and closing these valves. However, there must also be a sufficient overpressure in the reservoirs 7, 9 compared to the volume of the container 1 in order to generate a volume flow of the liquid when the active valve is open.

In the same way, the liquid supply from the individual reservoirs 7a, 7b, 7c, 7d of the 2 shown variant, which are each connected to the pressure sensor 11 via a pressure supply line 13a, 13b, 13c, 13d equipped with a 3/2-way changeover valve Va, Vb, Vc, Vd.

In contrast to the 1 The variant shown, in which all reservoirs 7, 9 are storage tanks filled with liquid in advance, is in 2 For example, a reservoir, the reservoir 7a, is designed as a sampler which can be filled with a liquid S, e.g. a sample to be analyzed, in an upstream filling process within the device according to the invention. For this purpose, this reservoir 7a has a sample feed line LS which opens into the reservoir interior and is equipped with a valve VS1, preferably a check valve, and the reservoir interior is connected to a vacuum pump Pv via a branch Lv equipped with a valve Vv which is connected between the reservoir 7a and valve Va into the pressure feed line 13a. By applying a vacuum to the reservoir interior, the liquid S can now be sucked into the reservoir 7a via the sample feed line LS. During this time, the fill level in the reservoir interior is preferably monitored by a corresponding sensor - here represented by two electrodes E1, E2. In order to prevent liquid from entering via the supply line 17a leading to the container 1 during the filling process, a further valve VS2, preferably also a check valve, is provided in the outlet of the reservoir 7a connected to the supply line 17a.

In 3 is an alternative design of the 1 This embodiment differs from the one in 1 shown device in that the container 1 comprises a plunger 51 which is movable within the container 1 and which divides the container 1 into a liquid space 52 into which the filling opening 3 opens, and a gas space 53 which is connected to the pneumatic pressure transmitter 11 via the pneumatic connection 43. The plunger 51 lies in a liquid- and gas-tight manner against the, for example, cylindrical, inner wall of the container 1. For example, the container 1 in this embodiment can be designed in the form of a conventional syringe, preferably a disposable syringe made of plastic, with a syringe body, in particular a cylindrical one, and a plunger 51 which is movable therein and lies in a liquid- and gas-tight manner against the inner wall of the syringe body, and a syringe nozzle opposite this, for example a cone-shaped one, which serves as the filling opening 3. The liquid space 52 enclosed between the plunger 51 and the syringe nozzle serves to accommodate liquid which is fed into the container 1 via the filling opening 3. The gas chamber 53 formed on the side of the piston facing away from the liquid chamber 52 is connected via a pneumatic connection 43 to the pressure sensor 23 and, when the valve V3 is closed, to the pneumatic pressure transmitter 11.

The storage units 7 and 9 also have the design according to 3 a cavity for liquid intake, in which a movable plunger 54, 55 is arranged, which rests liquid-tight against the inner wall of the cavity. The plungers 54, 55 divide the reservoirs 7, 9 into a liquid chamber 56, 57 filled with the liquid A, B and a gas-filled gas chamber 58, 59, which can be pressurized via the pressure sensor 11 and the valves V1, V2. As in the case of the container 1, the liquid containers 7 and 9 in this embodiment can each be designed in the form of a conventional syringe made of glass or plastic with a syringe body, in particular a cylindrical one, and a plunger movable therein, which rests liquid- and gas-tight against the inner wall of the syringe body and a syringe nozzle, for example conical, opposite the plunger, wherein the syringe nozzle is connected to the supply line 17 or 19. By pressurizing the gas chambers 58, 59 by means of the pneumatic pressure transmitter 11, the piston can be moved forward, provided that the applied pressure is large enough to compensate the frictional force of the piston 54 or 55 and, if applicable, 51 on the respective inner wall of the container, to overcome the line resistances of the supply lines 17, 19, 20 and the breakthrough pressure of the valves VR1, VR2 and VR3, and thus transport liquid A, B into the supply lines 17, 19 and in this way in the direction of the container 1.

The advantages of this design of the container 1 and, if applicable, the storage units 7 and 9 with a movable plunger are the avoidance of mutual contamination of the liquid and gas phases, for example by microorganisms. It also prevents the gas used for pressurization from dissolving in the liquid. This also effectively prevents liquid from leaking out and evaporating from the storage units and/or containers. In addition, the use of disposable syringes is very easy to implement. The installation position does not have to be defined when using syringes as storage units and/or containers.

Apart from the special nature of sampling, the following statements apply to the 1 illustrated embodiment and its modification according to 3 accordingly also for the embodiment of 2 .

The container 1 has a predetermined initial volume V ₀ in its interior, which does not contain any liquid at the beginning of each operating cycle of the device. Any drops or residual moisture still adhering to the inner walls are considered negligible due to their extremely small influence on the method according to the invention. A device is connected to the container 1, which serves to enclose gas, in particular air, under an initial pressure p ₀ in the predetermined initial volume V ₀ before the liquid flows in. In the embodiment according to 3 the initial volume V ₀ comprises the volume of the gas space 53 in an initial state of the container 1, in which the plunger 51 is preferably in an initial position near the filling opening 3 of the container 1.

Preferably, the controllable pneumatic pressure sensor 11, which is already present, is connected to the container 1 via a further pressure supply line 21 equipped with a valve V3, preferably a 3/2-way changeover valve. The output pressure p ₀ can be a pressure p generated by the pressure sensor 11, which is applied to the container 1 via the pressure supply line 21. Preferably, however, the above-mentioned reference pressure p _B , i.e. preferably the atmospheric pressure, is used as the output pressure p ₀ , which is applied to the container 1 by appropriately controlling the 3/2-way changeover valve V3. The gas thus located in the output volume V ₀ in the container 1 is then enclosed by the container 1 being sealed gas-tight and pressure-tight by completely closing the valve V3. The output pressure p ₀ then prevails inside the now closed system.
Alternatively, the initial volume V ₀ could be filled with air under atmospheric pressure via a ventilation opening in container 1 (not shown here) and then sealed gas-tight by means of a suitable closure.

In order to be able to predetermine the initial volume V ₀ in a reproducible manner, a defined initial state of the device is preferably brought about in advance, in which the supply lines 17, 19 and 20 are filled with liquid A, B up to the respective valve VR1, VR2 and VR located therein. The reproducibly predeterminable initial volume V ₀ now includes the remaining line volume of the supply lines 17, 19 and 20 not filled with liquid between the respective valve VR1, VR2 and VR and the container opening 3, the internal volume of the container 1 and the line volume inside the pressure supply line 21 from the container 1 to the valve V3. In the embodiment according to 3 the plunger 51 is brought into the starting position near the filling opening 3. To determine this starting position, a stop for the plunger 51 can be formed on the inner wall of the container.

A pressure sensor 23 is connected to the container 1, with which a gas pressure p _G is measured inside the container 1. If the pressure sensor 23 is not arranged directly inside the container 1, the internal volume of the connecting line 22, via which the gas pressure p _G is fed to the pressure sensor 23, also forms a component of the output volume V ₀ .

In a first process step - as already explained above - the gas is enclosed in the output volume V ₀ at the output pressure p _0. Preferably, while the output volume V ₀ is pressurized with the output pressure p ₀ , the liquids in the reservoirs 7, 9 are also pressurized with gas at the output pressure p ₀ via the 3/2-way changeover valves V1, V2 installed in their pressure supply lines 13, 15. This creates a defined initial situation in which there is no pressure drop via the check valves VR1, VR2 or VR. The check valves VR1, VR2 or VR prevent liquid from penetrating the container 1 in this process step.

In the next process step, the container 1 filled with gas under the initial pressure p ₀ is completely closed by the valve V3 gas-tight, and the outlet pressure p ₀ in container 1 is measured with the pressure sensor 23.

A flow of liquid is then caused from one or more reservoirs 7, 9 into the container 1. For this purpose, the pressure p generated by the pressure transmitter 11 is fed via the pressure supply lines 13, 15 by appropriately controlling the valves V1, V2 exclusively to the reservoirs 7, 9 that are to dispense liquid. To cause the flow of liquid into the container 1, the pressure p of the pressure transmitter 11 is increased to a pressure p that is far enough above the pressure prevailing inside the container 1 to overcome the breakthrough pressure of the respective check valve VR1, VR2 or VR and the flow resistance of the respective supply line 17, 19 and the supply line 20. In the embodiment according to 3 In addition, the frictional resistance of the pistons 54, 55 arranged in the reservoirs 7, 9 and of the piston 1 arranged in the container 1 must be overcome. The higher the pressure p, the greater the liquid flow.

The liquid flowing into the container 1, which in the embodiment according to 3 causes a displacement of the piston 51 in the direction of the pneumatic connection 43, compresses the gas enclosed in the container 1, in particular in the gas space 53, to a gas volume V _G which depends on the total inflow volume V(t) of the liquid and is approximately equal to the difference between the initial volume V ₀ and the volume V(t) of the total liquid flowing in up to the respective point in time t. Minor, usually negligible, deviations from this difference are based on the compressibility of the respective liquid and the solubility of the gas in the respective liquid. The inflowing liquid thereby causes an increase in the gas pressure p _G (t) of the gas in the container 1 compared to the initial pressure p ₀ , which depends on the inflow volume V(t) and the inflowing volume flow dV(t)/dt.

According to the invention, the gas pressure p _G (t) of the gas in the container 1 is measured as a function of time t, and based on the measured gas pressure p _G (t), the total volume V(t) flowing into the container 1 up to time t and/or the volume flow dV(t)/dt flowing into the container 1 at time t is determined.

Assuming that the enclosed gas behaves like an ideal gas, the Boyle-Mariotte law applies, according to which the product of gas pressure p _G and gas volume V _G of the enclosed gas is constant at constant temperature, and is therefore equal to the product of initial pressure p ₀ and initial volume V _0. This approximately gives: $$p_G{V}_G=p_G\left(V_0-V\right)=p_0{V}_0$$

und der zur Zeit t einströmende Volumenstrom dV(t)/dt zu: $$\frac{dV\left(t\right)}{dt}=-V_0\frac{d}{dt}\left(\frac{p_0}{p_G\left(t\right)}\right)$$

Based on this relationship, the volume V(t) of the liquid that has flowed in up to time t is: $$V\left(t\right)=V_0\left(1-\frac{p_0}{p_G\left(t\right)}\right)$$

and the incoming volume flow dV(t)/dt at time t is: $$\frac{dV\left(t\right)}{dt}=-V_0\frac{d}{dt}\left(\frac{p_0}{p_G\left(t\right)}\right)$$

Both quantities can be calculated directly from the gas pressure p _G (t) measured as a function of time t.

For this purpose, the device comprises an electronic unit 25 connected to the pressure sensor 23, which determines the inflowing volume V(t ₎ and/or the inflowing volume flow dV(t ₎ /dt of the liquid during each operating cycle based on the gas pressure p _G (t) measured by the pressure sensor 23 as a function of time t after the container 1 filled with the initial volume V 0 of gas at the initial pressure p 0 has been closed.

Since it may be very difficult or time-consuming to determine the initial volume V ₀ in container 1 precisely and the behavior of the gas may differ slightly from that of an ideal gas, e.g. due to moisture contained therein, a calibration procedure is preferably carried out in advance.

For this purpose, a relative gas pressure p _R is defined, which is equal to a quotient of the initial pressure p ₀ and the measured gas pressure p _G. $$p_R=\frac{p_0}{p_G}$$

In the upstream calibration procedure, starting from the previously described defined initial state with the gas enclosed in the initial volume V ₀ under the initial pressure p ₀ , a characteristic value mv of the device is determined, which indicates the slope of the relative gas pressure p _R as a function of the inflowing volume V. $$m_V=\frac{d{p}_R}{dV}$$

This change in the relative gas pressure p _R per change in the inflow volume V can, for example, be determined by successively filling the container 1 with several known reference volumes and recording the associated relative gas pressures p _R as a function of the volume of liquid in the container 1 based on the gas pressures p _G measured in the process. Alternatively, the parameter mv can be determined by filling the container 1 with a constant, known reference volume flow of liquid, from which the inflow volume V is derived by integration over time, and recording the associated relative gas pressures p _R as a function of the inflow volume V based on the measured gas pressures p _G. In both cases, the slope of the recorded characteristic curve representing the relative gas pressures p _R as a function of the inflow volume V is determined, which is equal to the desired parameter mv.

The parameter mv is a constant which essentially corresponds to the negative reciprocal of the initial volume V ₀ and at the same time takes into account deviations of the behavior of the gas from that of an ideal gas.

verwendet werden.If such a calibration procedure cannot or should not be carried out, then - if the initial volume V ₀ is known or determined by measurement - an approximate value m _v ' can be used for the procedure described below instead of the parameter m _v with: $$m{\prime }_V=\frac{d{p}_R}{dV}=\frac{d\left(\frac{p_0}{p_G}\right)}{dV}=\frac{d\left(\frac{V_G-V}{V_0}\right)}{dV}=-\frac{1}{V_0}$$

be used.

Following the calibration procedure, the liquid is drained from container 1 and the defined initial state is restored.

The subsequent operation of the device preferably takes place in successive operating cycles in which, starting from the initial state, gas is enclosed in the initial volume V ₀ under the initial pressure p ₀ , the container 1 is then filled with liquid, and finally the total liquid that has flowed into the container 1 in the respective operating cycle is discharged from the container 1.

During the filling process, the total volume V(t) that has flowed in up to time t is determined as the quotient of the relative gas pressure p _R (t) reduced by 1 and the parameter mv. That is: $$V\left(t\right)=\frac{p_R\left(t\right)-1}{m_V}$$

During the filling process, a temporal rate of change dp _R /dt of the relative gas pressure p _R is determined based on the gas pressure p _G (t) measured as a function of time, and the volume flow dV(t)/dt of the inflowing liquid to be measured is set equal to a quotient of the temporal rate of change dp _R /dt of the relative gas pressure p _R and the parameter mv. $$\frac{dV\left(t\right)}{dt}=\frac{\frac{d{p}_R}{dt}}{m_V}$$

The total volume V(t) flowing into the container 1 up to time t can alternatively be determined by integrating or summing the volume flows dV(t)/dt measured in the latter way over this period.

Preferably, all components surrounding the volume V ₀ have approximately the same temperature, which is preferably at least approximately equal to the temperature of the gas enclosed in the volume V ₀ . Local temperature changes within the volume V ₀ , e.g. due to heating of the valve V3, should be avoided if possible, since this can cause pressure changes that lead to temperature-dependent measurement inaccuracies. A pressure change caused by a predominantly homogeneous temperature change of the gas enclosed in the volume V ₀ can be compensated for with the aid of a temperature sensor integrated into the volume V ₀ , e.g. based on the linear temperature dependence of the product of gas pressure p _G and gas volume V _G resulting from the equation of state of ideal gases.

The filling of the container 1 and the measurement of the inflowing volume V and/or inflowing volume flow dV/dt can now be continued until the gas pressure p _G in the container 1 or in the gas space 53 ( 3 ) reaches a predetermined maximum pressure p _Gmax . This maximum pressure is determined by various physical variables, such as the liquid absorption capacity of the container 1, the pressure resistance of the supply lines 17, 19 or 20 and of the container 1 and the maximum pressure of the pressure transmitter 11 or pressure sensor 23. The maximum pressure p _Gmax is, however, set to a pressure of less than 2 bar, e.g. to a pressure of 1 bar, relative to atmosphere. As a result, in the embodiments according to. 1 and 2 prevents the gas from dissolving in the liquid to any significant extent, which could otherwise impair the accuracy of the measurement. If the use of the device so requires, the filling can of course also be terminated before the maximum volume V _max of liquid in container 1 corresponding to the maximum pressure p _Gmax is reached.

Following the filling process, the liquid in container 1 is drained from container 1.

For this purpose, the container 1 is connected via a drain line 27 equipped with a drain valve V _A to a receiving vessel 29 into which the liquid in the container 1 can be drained. Here, too, a modular structure is preferably selected.

The receiving vessel 29 is preferably provided with a vent opening 31, through which its interior is subjected to the ambient pressure.

The drain valve V _A is preferably also a passive check valve which has a breakthrough pressure which is greater than the difference between the maximum gas pressure p _Gmax and the ambient pressure. This ensures that the drain valve V _A blocks the drain line 27 during the filling process.

To drain the liquid from the container 1, the liquid supply to the container 1 is interrupted - as already described above. The valve V3 is then opened and the liquid contained in the container 1 or the plunger 51 (see 3 ) is subjected to a pressure p via the pressure sensor 11 which is sufficiently dimensioned to allow the liquid to flow out through the check valve V _A via the discharge line 27. This means that the pressure p must be selected to be high enough to overcome the breakthrough pressure of the check valve V _A and the line resistance of the discharge line 27 and, if necessary, the frictional resistance of the piston 51. This pressurization causes the check valve V _A to open and the liquid to flow out into the receiving vessel 29.

After emptying the container 1, the device returns to its initial state and the next operating cycle can be carried out immediately in the manner described above.

The device preferably comprises a controller 33 connected to the pressure sensor 23, which, following the calibration process, uses the measured gas pressure p _G to bring about a fully automatic operation of the device according to the invention by appropriately controlling the pressure sensor 11, the valves V1, V2 and the valve V3. The controller 33 is, for example, an integral part of the electronic unit 25.

The device according to the invention can be used or operated in a variety of ways.

A first use is to operate the device as an automated micro-syringe for dosing liquids, which, for example, dispenses predetermined target volumes of individual liquids at predetermined times.

For this purpose, the controller 33 controls the liquid supply from at least one selected reservoir 7, 9, which is effected by the device for effecting the liquid flow, depending on the measured volume V(t) flowing into the container 1, and ends the liquid supply by closing the valves V1, V2 when the measured volume V(t) reaches the respective specified target volume. The control of the valves V1, V2 specifies from which reservoir 7, 9 or reservoirs 7, 9 the container 1 is filled with liquid until the respective target volume is reached in the respective operating cycle.

For example, in the container 1, a target volume V _SA of the liquid A can first be measured from the reservoir 7, which is then discharged via the drain line 27. Subsequently, a target volume V _SB of the liquid B can be measured from the reservoir 9, which is then discharged via the drain line 27. Likewise, by filling the container 1 in parallel with liquid A and B from both reservoirs 7, 9, a target volume V _SAB can be measured and subsequently discharged, which contains both liquids A and B.

In addition, the device is able to measure and dispense a target volume of a liquid that contains two or more different liquids A, B, provided in a corresponding number of reservoirs 7, 9, in a predetermined mixing ratio. For this purpose, the container 1 is successively filled with the predetermined target volumes V _SA , V _SB of the individual liquids A, B from the individual reservoirs A, B within a single operating cycle via a corresponding control of the device for effecting the liquid flow, wherein the achievement of the respective target volumes V _SA , V _SB is determined based on the measured in the total volume V(t) flowing into the container 1 and the flowing volume V already in the container 1 measured by the device at the beginning of filling with the respective liquid A, B from the respective reservoir 7, 9.

When successively filling the container 1 with the different target volumes V _SA , V _SB of the individual liquids A, B, it is preferable to start filling with the liquid A, B that requires the largest target volume V _SA , V _SB and then continue filling successively with the liquid A, B that requires the next smallest target volume V _SA , V _SB . This offers the advantage of a smaller relative measurement error in relation to the respective target volume V _SA , V _SB , caused by the measurement accuracy of the pressure sensor 23.

By expanding the 1 The number of different liquids that can be mixed and dosed in predetermined mixing ratios can be increased to three or more using the device shown for causing the liquid flow around further reservoirs that are connected in the same way and filled with other liquids. Alternatively, a modular structure can also be selected here, which enables a preferably also automated exchange of individual reservoirs.

In addition, the container 1 can be used as a mixing container which, after being filled with the individual target volumes V _SA , V _SB etc., is available as a storage device, in the sense of the storage devices 7, 9 described here, in a more complex device.

A further use of the device according to the invention consists in the generation of controlled volume flows of adjustable size.

The volume flow dV/dt flowing into the container 1 is regulated to a predetermined target value based on the measured incoming volume flow dV/dt by appropriately regulating the liquid supply into the container 1. For this purpose, a control device 35 is provided, preferably also integrated in the electronic unit 25 and connected to the control 33, which regulates the liquid supply accordingly by controlling the pressure sensor 11 and the valves V1, V2.

In this application, the container 1 is filled via a single feed line SP through which all the liquid flowing into the container 1 flows. The volume flow flowing through this feed line SP is therefore equal to the volume flow dV/dt flowing into the container 1 and is also regulated accordingly to the target volume flow.

The feed line SP here comprises the supply line 20 which is connected on the output side to the device for generating the liquid flow and through which the liquid flowing into the container 1 flows.

In the 1 In the device shown, one of the supply lines 17, 19 can be operated as part SP17, SP19 of the feed line SP by appropriately controlling the liquid supply. For this purpose, the container 1 is filled exclusively with liquid from one of the reservoirs 7, 9 by appropriately controlling the valves V1, V2 in the pressure supply lines 13, 15 leading to the reservoirs 7, 9, so that the total liquid flowing into the container 1 during this flow flows through the respective supply line 17 or 19.
Likewise, devices constructed analogously to the device shown can of course be used, in which some selected storage tanks open into a feed line on the output side, via which the entire liquid supply to the container 1 then takes place in this operating mode. In this variant too, the liquid supply from all other storage tanks not connected to the feed line is prevented by closing the corresponding valves in the corresponding pressure supply lines.

The automated generation of predetermined target volume flows through the feed line SP is of great advantage, especially when measuring and/or monitoring chemical and/or physical properties of the liquid flowing through the feed line SP, as well as when analyzing this liquid.

In this way, by means of the device, during the associated filling process, a volume flow flowing through a measuring and/or analysis device 37 inserted into the feed line SP can be regulated to a predetermined target volume flow that is optimal for the measurement and/or analysis.

Instead of or in addition to the measuring and/or analysis unit 37 inserted into the feed line SP - here formed by the feed line 20 - a further measuring and/or analysis device 37a, 37b can be inserted into the feed line 17 fed via the storage device 7 and/or into the feed line 19 to the container 1 fed via the storage device 9.

While the container 1 is filled exclusively with liquid A from the reservoir 7, the total volume flowing into the container 1 volume flow dV/dt through the supply line 17, which thereby becomes part SP17 of the feed line SP. Accordingly, the volume flow through the measuring and/or analysis device 37a can in this case be regulated to a predetermined target volume flow based on the measured volume flow dV/dt.

While the container 1 is filled exclusively with liquid B from the reservoir 9, the total volume flow dV/dt flowing into the container 1 flows through the supply line 19, which thereby becomes part SP19 of the feed line SP. Accordingly, the volume flow can also be regulated to a predetermined target volume flow by the measuring and/or analysis device 37b in this case based on the measured volume flow dV/dt.

If the container 1 - as mentioned above - is used as a mixing container which, after being filled with individual target volumes V _SA , V _SB etc., is used as a storage device in a more complex device in the sense of the storage devices 7, 9 described here, the drain line 27 can also be operated as a feed line in the sense described above and the volume flow can be regulated by a measuring and/or analysis device - not shown here - inserted into the drain line 27. In addition, it is of course always possible in principle to insert measuring and/or analysis devices into the drain line 27 which are also functional without regulating the volume flow flowing through them.

The device according to the invention is therefore extremely versatile.

The simplest use is the pure measurement of the inflowing volume V(t) and/or the inflowing volume flow dV(t)/dt into the container 1.

In addition, as described above, it can be used to measure predetermined target volumes V _SA , V _SB and dispense them individually or in predetermined mixing ratios. This is particularly required in chemical and biochemical analysis in a homogeneous liquid phase.

In addition, the device can be used to set target volume flows through the feed line SP, or SP17 or SP19. This property is particularly required in surface-bound chemical and biochemical analysis, e.g. for the operation of an automated immunoassay.

It is thereby readily possible to use the same device in one operating cycle or in successive operating cycles both for generating a target volume flow through one of the measuring and/or analysis devices 37, 37a, 37b and for highly precise dosing of predetermined target volumes of individual liquids or of several liquids to be mixed in a predetermined mixing ratio of the individual liquids A, B provided in the storage 7, 9.

For example, the container 1 can first be filled with a predetermined target volume V _SA of the liquid A by the measuring and/or analysis device 37a inserted in the supply line 17 while maintaining a predetermined target volume flow, then filled with a predetermined target volume V _SB of the liquid B by the measuring and/or analysis device 37b inserted in the supply line 19 while maintaining a predetermined target volume flow, and finally the liquid composed of the liquids A and B in the container 1 in the mixing ratio predetermined by the two target volumes V _SA and V _SA can be dispensed.

The devices according to the invention offer the advantage that they can be used to carry out dosing and volume flow control in almost any manner, one after the other and/or in combination with one another. The device according to the invention can therefore be used to carry out extremely complex processes and methods fully automatically.

The modular design offers the advantage that a high degree of flexibility is provided through the preferably automated exchange of storage tanks 7, 9 and/or receiving vessels 25 and that practically any number of different liquids A, B can be processed.

Ideally, all liquid-containing and liquid-carrying components, i.e. the reservoirs 7, 9, the container 1, the receiving vessels 29, and the supply lines 17, 19, 20, are designed as modular components that are assembled to form an assembly.
Likewise, all other mechanical, pneumatic and electronic components, i.e. the pressure transmitter 11, the electronic unit 25, the pressure sensor 23 and the pressure supply lines 13, 15, 21, 22 and the valves V1, V2, V3 contained therein, are preferably combined into one unit. This unit can then be used in conjunction with different assemblies, whereby the connection of the unit to the respective assembly is carried out in a simple manner via pneumatic connections 39, 41, 43, advantageously equipped with liquid-impermeable gas-permeable membranes or filters. A pneumatic interface is also described in the German patent application filed on March 25, 2010 by the applicant. rin with the registration number 10 2010 00 33 04.9 described.

1

container

3

Filling opening

5

Liquid supply device

7

Storage

9

Storage

11

adjustable pneumatic pressure sensor

13

Pressure supply line

15

Pressure supply line

17

Supply line

19

Supply line

21

Pressure supply line

23

Pressure sensor

25

electronic unit

27

Drain line

29

Receptacle

31

Vent opening

33

steering

35

Control device

37

Measuring and/or analysis device

39

pneumatic connection

41

pneumatic connection

43

pneumatic connection

51

Rubber stamp

52

Fluid space

53

Gas room

54

Rubber stamp

55

Rubber stamp

56

Fluid space

57

Fluid space

58

Gas room

59

Gas room

Claims (20)

Device for measuring a volume flow (dV(t)/dt) of a liquid (A, B) flowing into a container (1) and/or a volume (V(t)) of the liquid (A, B) flowing into the container (1), with - a device connected to the container (1) which serves to enclose gas in a predetermined initial volume (Vo) in the interior of the container (1) before the liquid flows in under an initial pressure (po), - a pressure sensor (23) for measuring the gas pressure (p _G ) in the container (1), - a liquid supply device (5) connected to a filling opening (3) of the container (1) which opens into the interior of the container (1), which serves to supply liquid (A, B) to the container (1), wherein the container (1) comprises a plunger (51) which is movable in the interior of the container (1), rests liquid-tight and gas-tight against a container wall enclosing the interior, which plunger fills the container (1) into a liquid space (52) into which the filling opening (3) opens, and a gas space (53) which is connected to the device which serves to enclose gas in a predetermined initial volume (Vo) in the interior of the container (1) before the liquid flows in under an initial pressure (po), and to the pressure sensor (23), and - an electronic unit (25) which, after the container (1) filled with the initial volume (Vo) of gas under the initial pressure (po), determines the volume (V(t)) of the inflowing liquid and/or the volume flow (dV(t)/dt) of the inflowing liquid on the basis of the gas pressure (p _G ) measured by the pressure sensor (23) after the container (1) has been closed and which is filled with the initial volume (Vo) of gas under the initial pressure (po). Device according to Claim 1 , wherein the electronic unit (25) is arranged to determine the volume (V(t)) flowing in up to time (t) on the basis of the gas pressure (pG(t)) measured at time (t). Device according to Claim 1 , wherein the electronic unit (25) is configured to determine a temporal change in the measured gas pressure (p _G ) and to determine the volume flow (dV(t)/dt) flowing into the container (1) at time (t) on the basis of the temporal change in the measured gas pressure (p _G ) at time (t). Device according to Claim 1 , wherein the electronic unit (25) is designed to - define a relative gas pressure (p _R ) which is equal to a quotient of the initial pressure (po) and the gas pressure (p _G ), - determine a parameter (mv, m'v) which indicates the gradient of the relative gas pressure (p _R ) as a function of the inflowing volume (V(t)), - determine the relative gas pressure (p _R ) as a function of time (t) while the liquid is flowing into the container (1) on the basis of the gas pressure (p _G ) measured as a function of time (t), - determine the volume (V(t)) and/or the volume flow (dV(t)/dt) on the basis of the relative gas pressure (p _R ). Device according to Claim 4 , wherein the electronic unit (25) is adapted to determine the characteristic quantity (m _v ) in a preceding calibration procedure. Device according to Claim 4 or 5 , wherein the electronic unit (25) is designed to determine the volume (V(t)) flowing in up to time (t) as the quotient of the relative gas pressure (p _R ) reduced by 1 at time (t) and the characteristic variable (mv, m'v), and/or - to determine a temporal rate of change of the relative gas pressure (dp _R (t)/dt), and - to determine the volume flow (dV(t)/dt) flowing in at time (t) as the quotient of the temporal rate of change of the relative gas pressure (dp _R (t)/dt) and the characteristic variable (mv, m'v). Device according to one of the Claims 1 - 6 which comprises a controller (33) which controls the liquid supply effected by the liquid supply device (5) as a function of the measured volume flowing into the container (1) (V(t)) or the measured inflowing volume flow (dV(t)/dt). Device according to Claim 7 , in which the controller (33) stops the liquid supply when the measured volume (V(t)) reaches a predetermined target volume (V _SA , V _SB ). Device according to one of the Claims 1 until 8th , the liquid supply device (5) of which comprises at least one reservoir (7, 9) filled with liquid (A, B) and a device for causing a liquid flow from the reservoir (7, 9) into the container (1), the reservoir (7, 9) having a cavity in which the liquid (A, B) is received, and in which a movable plunger (54, 55) is arranged which rests in a liquid- and gas-tight manner on an inner wall surrounding the cavity and which divides the at least one reservoir into a liquid space (56, 57) which is connected to the container (1) via at least one liquid line and a gas space (58, 59) which is operatively connected to the device for causing a liquid flow from the reservoir (7, 9) into the container (1). Method using a device according to one of the Claims 1 until 9 operates, wherein the liquid supply device (5) comprises at least two reservoirs (7, 9) filled with liquid (A, B) and a device for causing a liquid flow from the reservoirs (7, 9) into the container (1), in which - the gas is enclosed in the predetermined initial volume (Vo) under the initial pressure (po), - the container (1) is successively filled with predetermined target volumes (V _SA , V _SB ) of liquids (A, B) from two or more different reservoirs (7, 9) via the device for causing the liquid flow, - wherein the achievement of the respective target volumes (V _SA , V _SB ) of the individual liquids (A, B) is monitored on the basis of the measured total volume (V(t)) flowing into the container (1) and the volume (V(t)) already in the container (1) at the start of the respective filling process with the respective liquid (A, B) from the respective reservoir (7, 9) and measured with the device. Procedure according to Claim 10 , in which, during the successive filling of the container (1) with the different target volumes (V _SA , V _SB ) of the individual liquids (A, B), filling begins with the liquid (A, B) for which the largest target volume (V _SA , V _SB ) is required, and filling is then continued successively with the liquid (A, B) for which the next smallest target volume (V _SA , V _SB ) is required. Device according to one of the Claims 1 until 9 , in which - the liquid supply device (5) feeds the liquid through a feed line (SP, SP17, SP19) into the container (1), - a volume flow of the liquid through the feed line (SP, SP17, SP19) is equal to the volume flow flowing into the container (dV(t)/dt), and - a control device (35) is provided which controls the liquid supply caused by the liquid supply device (5) on the basis of the measured volume flow flowing into the container (dV(t)/dt) such that the volume flow through the feed line (SP, SP17, SP19) and the volume flow into the container (1) correspond to a predetermined target volume flow. Device according to Claim 12 , in which - a measuring or analysis device (37, 37a, 37b) is inserted into the feed line (SP, SP17, SP19), - a volume flow of the liquid through the measuring or analysis device (37, 37a, 37b) is equal to the volume flow through the feed line (SP, SPa, SPb) and equal to the volume flow flowing into the container (1) (dV(t)/dt), and - the control device (35) controls the volume flow through the measuring or analysis device (37, 37a, 37b) to a predetermined target volume flow based on the measured volume flow flowing into the container (1) (dV(t)/dt). Device according to one of the Claims 1 until 9 , at the - the liquid supply device (5) comprises at least one reservoir (7, 9) filled with liquid (A, B) and a device for causing a liquid flow from at least one of the reservoirs (7, 9) into the container (1), and - the device for causing the liquid flow comprises a controllable pneumatic pressure sensor (11), -- which is connected to the reservoirs (7, 9) via a pressure supply line (13, 15) provided with a controllable valve (V1, V2), in particular a 3/2-way changeover valve, and - the liquid flow is caused by pressurizing the liquid (A, B), in particular via movable pistons (54, 55) arranged in the reservoirs (7, 9), in the reservoirs (7, 9) with a pressure (p) generated by the controllable pneumatic pressure sensor (11). Device according to Claim 14 , in which the adjustable pneumatic pressure sensor (11) is connected to the container (1) via a pressure supply line (21) which can be closed with a controllable valve (V3), in particular a 3/2-way changeover valve. Device according to Claim 14 or 15 , in which the liquid supply device (5) is connected to the container (1) via at least one supply line (17, 19, 20) equipped with a valve (VR, VR1, VR2), in particular a check valve. Method comprising a device according to Claim 14 , 15 or 16 operates in which operating cycles are carried out in each of which - the container (1) and the liquid (A, B) in the accumulators (7, 9) are previously pressurized with the output pressure (po) via the 3/2-way changeover valves (V1, V2, V3), - the valve (V3) in the pressure supply line (21) leading from the pressure sensor (11) to the container (1) is closed, - a liquid flow into the container (1) is brought about by pressurizing liquid (A, B) from at least one of the accumulators (7, 9) with a pressure (p) generated by the pressure sensor (11), and - finally, the total liquid which has flowed into the container (1) in the respective operating cycle, in particular by pressurization, is discharged from the container (1). Device according to Claim 15 or 16 , in which the container (1) is connected via a drain line (27) equipped with a valve (V _A ), in particular a check valve, to a receiving vessel (29) which is subjected to ambient pressure via a vent opening (31), into which liquid in the container (1) can be drained. Method comprising a device according to Claim 18 operates in which the liquid is drained from the container (1) at the end of a filling cycle by - interrupting the liquid supply to the container (1), and - the liquid contained in the container (1) is subjected to a pressure (p) via the pressure sensor (11) at which the liquid flows out through the check valve (V _A ) via the drain line (27). Method using a device according to one of the Claims 1 until 9 , 12 until 16 or 18 operates in which operating cycles are carried out in each of which - gas is enclosed in the predetermined initial volume (Vo) under the initial pressure (po), - a liquid flow is caused into the container (1) and the inflowing volume flow (dV(t)/dt) and/or the inflowing volume (V(t)) is measured, - the liquid supply to the container (1) is interrupted before the gas pressure (p _G ) in the container (1) exceeds a predetermined maximum pressure (p _Gmax ), and - finally, the total liquid which has flowed into the container (1) in the respective filling cycle is discharged from the container (1).