Apparatus and method for measuring carbon dioxide

Abstract

The invention relates to a method for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid. The method comprises the step of providing a fluid-tight container containing a sample of a liquid having carbon dioxide dissolved therein. The method also involves agitating the sample of liquid while allowing the volume of the container to change from a first volume towards a second volume associated with an equilibrium state. In the equilibrium state, the headspace pressure within the container is equal to the pressure of the environment surrounding the container and the carbon dioxide dissolved in the sample of liquid is in chemical equilibrium with the carbon dioxide in the headspace volume. The method further comprises the step of determining an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume. The invention also relates to a measuring device and a method for manufacturing a measuring device.

Description

Technical Field

[0001] The present invention relates to a method for measuring carbon dioxide, particularly carbon dioxide dissolved in a liquid, and an apparatus for measuring carbon dioxide. Background Technology

[0002] Measuring the level of carbon dioxide gas dissolved in liquids is particularly meaningful in the carbonated beverage industry. For example, as part of quality control checks, it is important to be able to check the carbonation level of beer (e.g., by brewery operators). In particular, it is important to be able to provide accurate measurement results quickly and without requiring skilled operators.

[0003] The known methods in the prior art for measuring carbonation are the Heard method (Heard, BT "A rapid manometric / volumetric method for the determination of dissolved carbon dioxide content of beer in tanks", Journal of the Institute of Brewing 79.5 (1973): 371-376) and the ASBC Beer-13C method (American Society of Brewing Chemists, Methods of Analysis, 14th Edition, Beer-13 Dissolved Carbon Dioxide. American Society of Brewing Chemists, St. Paul, Minnesota, 2011). Typically, both methods involve drawing a volume of carbonated liquid into a syringe, then closing the syringe (to provide a sealed measuring chamber) and partially withdrawing the syringe plunger so that the pressure inside the syringe is lower than the ambient pressure. The user holds the plunger in this expanded position while shaking the syringe. For both methods, the determination of the carbonation level is based on Henry's Law, which states that, for a given temperature, the partial pressure of a gas in equilibrium with a liquid is proportional to the amount of gas dissolved in that liquid. For the Heard method and the ASBC Beer 13C method, Henry's Law applies after chemical equilibrium has been achieved by agitating the fluid while the plunger is kept in the expanded position.

[0004] It was in this context that the present invention was designed. Summary of the Invention

[0005] According to one aspect of the present invention, a method is provided for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the method comprising:

[0006] Provide an impermeable container for holding a liquid sample containing dissolved carbon dioxide;

[0007] The liquid sample is stirred while allowing the volume of the container to change from a first volume toward a second volume associated with the equilibrium state;

[0008] In this equilibrium state, the pressure in the headspace of the container is equal to the pressure of the surrounding environment, and the carbon dioxide dissolved in the liquid sample is in chemical equilibrium with the carbon dioxide in the headspace volume; and

[0009] This second volume serves as an indication of the amount or concentration of carbon dioxide dissolved in the liquid.

[0010] Accurate measurement results can be conveniently obtained by using the second volume defined above to determine the amount or concentration of carbon dioxide dissolved in the liquid. Other methods in the prior art rely on measuring multiple container volumes, including methods where the container volume is maintained by the user such that the pressure inside the container is less than the ambient pressure during agitation. The inventors have recognized that by allowing the container volume to change toward an equilibrium state in which the system is in mechanical equilibrium (i.e., internal pressure equals external pressure) and chemical equilibrium (i.e., the rate at which carbon dioxide dissolves into the liquid equals the rate at which carbon dioxide is released from the liquid), the volume associated with this equilibrium state can be used to provide accurate carbon dioxide measurement results more conveniently compared to other prior art methods. In particular, the inventors have recognized that by applying gas laws (e.g., the ideal gas law and Henry's law) to this system, the concentration / amount of carbon dioxide dissolved in the liquid can be determined using the measured second volume as defined above. Fewer container volume measurements are required compared to prior art methods, thereby reducing measurement uncertainty. Furthermore, it is not necessary to maintain the container at a fixed volume during the agitation step, thus making the method simpler (more convenient) to implement.

[0011] A container is impermeable to fluids, meaning it substantially prevents fluids (e.g., gases or liquids) from leaving or entering the container. That is, the container is configured such that it can be substantially sealed. When the container is impermeable / sealed, its volume can change, but the molar amount of gas (i.e., gas dissolved in the liquid and gas present in the headspace) remains substantially constant. Typically, the container will have at least one fluid inlet that can be opened and closed (e.g., via a valve). To avoid ambiguity, it should be understood that the container will be considered impermeable to fluids, where any very small fluid rate leaving or entering the container is small enough to have only a negligible effect on the accuracy of the measurement results.

[0012] An indication of the amount or concentration of carbon dioxide dissolved in a liquid can be an indication of the amount of carbon dioxide dissolved in the liquid.

[0013] The container may be defined at least partially by a movable first wall. For example, the wall may be movable from a first position corresponding to a first container volume to a second position corresponding to a second container volume. In some embodiments, the wall may be defined by a piston surface. The container may be partially defined by a syringe barrel and a plunger (i.e., piston) within the barrel. Components of the device (e.g., movable parts) may include low-friction materials (such as a polyurethane coating) such that only a small pressure difference is required between the interior and exterior environments of the container to change the container volume.

[0014] Agitation of the liquid sample allows for changes in the volume of the container. Agitation can include mechanical agitation (such as shaking the container or stirring the liquid sample) and / or electrical agitation (such as electrolyzing the liquid sample). In other words, it should be understood that agitation is essentially any process that promotes the carbon dioxide dissolved in the liquid sample to reach equilibrium faster than if the container were not agitated.

[0015] A stirring step can cause and / or promote the release of carbon dioxide from the liquid, and cause the container volume to change toward a second volume. Typically, a stirring step will increase the rate of carbon dioxide release from the liquid and the rate at which carbon dioxide dissolves from the headspace into the liquid, causing the container volume to change toward a second volume associated with equilibrium more rapidly.

[0016] It should be understood that headspace pressure corresponds to the pressure of the gas in the headspace of the container.

[0017] In equilibrium, the pressure in the top space inside the container is equal to the pressure of the surrounding environment (i.e., any difference between the two will not be large enough to cause further changes in volume).

[0018] It should be understood that, at least after the gas / vapor is released from the liquid, the container volume will include the liquid volume of the liquid sample and the headspace volume (i.e., the volume of vapor and / or gas above the liquid sample). In equilibrium, the headspace pressure within the container (i.e., the pressure of the gas and / or vapor in the headspace volume) is equal to the pressure of the environment surrounding the container.

[0019] It should be understood that a liquid sample can be a portion of the liquid from which the dissolved carbon dioxide being measured is being measured. For example, a liquid sample can be a sample of a liquid (e.g., beer) taken from a pressurized container.

[0020] Indications for determining the amount or concentration of carbon dioxide dissolved in a liquid based on a second volume may involve determining the concentration and / or amount of carbon dioxide dissolved in a liquid sample.

[0021] The amount of carbon dioxide dissolved in a liquid can be indicated in molar amounts. Alternatively, the amount of carbon dioxide dissolved in a liquid can be expressed in units of mass or volume. The concentration of carbon dioxide dissolved in a liquid can be indicated in units involving ratios. For example, the concentration of carbon dioxide dissolved in a liquid can be indicated by a volume ratio, a mass ratio, or a mass-to-volume ratio. A concentration / amount indication can be an indication that the concentration / amount is within a specific range or above (or below) a predetermined value rather than an exact value. A concentration / amount indication can also be an estimate.

[0022] In some embodiments, the step of determining the amount or concentration of carbon dioxide dissolved in the liquid is also based on the volume of the liquid sample. Alternatively, it is possible that the step of determining the amount or concentration of carbon dioxide dissolved in the liquid is based on the ratio of the difference between the second volume and the volume of the liquid sample to the volume of the liquid sample. It is also possible to add an antifoaming agent to the liquid sample before determining its volume to improve the accuracy of the liquid sample volume measurement.

[0023] Using the ideal gas law and Henry's gas law, the inventors have realized that the amount or concentration of carbon dioxide dissolved in a liquid can be determined based on the volume of the liquid sample and the second volume of the container. In particular, the inventors have realized that the concentration / amount of carbon dioxide can be determined based on the ratio of the difference between the second volume and the volume of the liquid sample to the volume of the liquid sample.

[0024] The liquid volume can be the volume of the liquid at atmospheric pressure. In some embodiments, the liquid volume can be the volume of the liquid before the agitation step.

[0025] If the test is performed at standard temperature and pressure, the concentration of dissolved carbon dioxide can be determined using the following equation. :

[0026]

[0027] in, It is the Bunsen coefficient of carbon dioxide in the liquid being tested. It is the second volume. It is the volume of the liquid sample, and The Bunsen coefficient is expressed in units of the ratio of gas to solvent volume (i.e., the gas volume of the solvent). It is defined as the volume of gas absorbed by a unit volume of solvent (at the measurement temperature) at a partial pressure of 1 atmosphere, reduced to 273.15 K and 1 atmosphere. The Bunsen coefficient varies with temperature and the product being tested. In some embodiments, the value used for the Bunsen coefficient will be based on ASBC Beer-13 for a typical beer.

[0028] In some embodiments, if the device will be used at a temperature other than standard pressure or temperature, the calculation of the dissolved carbon dioxide concentration can be modified to account for the effect of the difference in temperature and pressure compared to standard temperature and pressure.

[0029] It is possible that the steps for determining the amount or concentration of carbon dioxide dissolved in a liquid are not based on volumes other than the sample liquid volume and the second volume.

[0030] By using a second volume, the inventors have realized that an indication of the concentration or amount of carbon dioxide can be determined using only two volume measurements, thereby limiting the measurement uncertainty associated with volume measurements.

[0031] It is possible that the step of determining the amount or concentration of carbon dioxide dissolved in the liquid is further based on the partial pressure of a second gas present in the headspace of the container. The second gas could be water vapor.

[0032] The accuracy of the determined indication is further improved by using carbon dioxide to determine the partial pressure of the second gas present in the headspace.

[0033] It is possible that the steps for determining the amount or concentration of carbon dioxide dissolved in a liquid are further based on pressure measurements and / or temperature measurements. Temperature measurements may include the temperature of the liquid.

[0034] The inventors have recognized that a particularly rapid determination of the amount or concentration of carbon dioxide dissolved in a liquid can be achieved, even based on estimated temperature and / or estimated pressure. The accuracy of the determination can be further improved by using measured values ​​of temperature and pressure.

[0035] It is possible that the liquid sample has an initial concentration and / or initial amount of carbon dioxide dissolved therein, wherein the indication for determining the amount or concentration of carbon dioxide dissolved in the liquid includes determining the initial concentration or initial amount, respectively.

[0036] It is possible that the steps for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid include obtaining a first value of the amount or concentration of carbon dioxide dissolved in the liquid, and obtaining an adjusted value of the amount or concentration of carbon dioxide dissolved in the liquid based on a measured temperature and / or a measured pressure.

[0037] The accuracy of determination is improved by obtaining adjusted values ​​of the amount or concentration of carbon dioxide based on measured temperature and / or pressure.

[0038] It should be understood that any step in any of the methods described above can be automated. In other words, it is possible to perform a step without any manual intervention. It is also possible for the next step to begin without any manual intervention after the previous step.

[0039] According to another aspect of the present invention, a method for manufacturing a measuring device for performing the method according to any of the preceding claims is provided, the method comprising:

[0040] Provide the container for containing the liquid sample; and

[0041] A carbon dioxide indicator is provided to indicate the concentration or amount of carbon dioxide dissolved in the liquid based on the second volume, and / or

[0042] A sensor for sensing the volume of a container and a processor configured to receive the output from the sensor as input are provided.

[0043] In some embodiments, the method may involve a first calibration procedure that correlates the second volume with the concentration or amount of dissolved carbon dioxide. In embodiments where the container is partially defined by a movable wall (e.g., a piston), it is possible that the first calibration procedure involves correlating the position of the movable wall with the concentration or amount of dissolved carbon dioxide. The method may involve marking points on the surface of the container based on the first calibration procedure. The first calibration procedure may take into account the influence of the weight of components of the measuring device on the position of the movable wall.

[0044] In some embodiments, the method may involve a second calibration procedure that correlates the location of the fluid interface of the liquid sample with the volume of the liquid sample. In embodiments where the container includes a valve / inlet, the second calibration procedure may take into account the liquid contained in the valve and / or inlet. The method may involve marking points on the surface of the container based on the second calibration procedure.

[0045] According to another aspect of the present invention, a measuring device is provided for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the measuring device comprising:

[0046] A container for holding liquid samples, the container having a variable volume;

[0047] First carbon dioxide indicator;

[0048] In use, the container defines a closed system that can progress toward satisfying a first equilibrium condition and a second equilibrium condition.

[0049] The first equilibrium condition corresponds to the pressure in the headspace of the container being equal to the pressure of the environment surrounding the container, and the second equilibrium condition corresponds to the carbon dioxide dissolved in the liquid sample being in chemical equilibrium with the carbon dioxide in the headspace volume.

[0050] The volume of the container can be changed toward a second volume that is at least associated with the first equilibrium condition; and

[0051] The first carbon dioxide indicator is configured to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume after the closed system has progressed toward satisfying the first and second equilibrium conditions.

[0052] Accurate carbon dioxide measurement results can be achieved in a convenient manner by providing a measuring device with a first carbon dioxide indicator (which is used to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on a second volume).

[0053] A container defines a closed system, such that the container has a closed configuration in which fluids (e.g., gases or liquids) are prevented from leaving or entering the container, thereby allowing progress toward mechanical and chemical equilibrium (i.e., satisfying a first equilibrium condition and a second equilibrium condition). In other words, the container is configured such that it can define a substantially closed system (e.g., a substantially sealed configuration). Typically, the container will have at least one fluid inlet that can be opened and closed (e.g., via a valve).

[0054] It is possible that, during use, while the liquid sample is being stirred, the volume of the container can change towards the second volume. It is also possible that the second volume is related to both the first and second equilibrium conditions.

[0055] Carbon dioxide indicators may include digital displays. Carbon dioxide indicators may include markings on a surface associated with the container (e.g., the surface of the container). Carbon dioxide indicators may include a graduated scale, which typically has numerical labels associated with at least a subset of the scale to indicate the corresponding amount and / or concentration of dissolved carbon dioxide.

[0056] It is possible that the first carbon dioxide indicator is configured to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the volume of the liquid sample. The first carbon dioxide indicator may also be configured to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the ratio of the difference between the second volume and the volume of the sample liquid to the volume of the sample liquid.

[0057] It is possible that the first carbon dioxide indicator visually indicates the amount or concentration of carbon dioxide dissolved in the liquid, and the measuring device further includes a first volume indicator for visually indicating the volume of the liquid sample. Alternatively, it is possible that the first volume indicator is associated with the first carbon dioxide indicator such that, in use, if the volume of the liquid sample can be determined using the first volume indicator, the concentration or amount of carbon dioxide can also be determined using the first carbon dioxide indicator.

[0058] In some embodiments, the first volume indicator may be a mark (e.g., a measuring line) associated with the surface of the container. The first volume indicator can provide an indication of the amount of liquid that should be received into the container for carbon dioxide determination, thereby improving the ease of operation of the device, as the user can quickly identify whether the volume of the sample liquid is appropriate.

[0059] It is possible that the first volume indicator is one of a plurality of volume indicators, and the first carbon dioxide indicator is one of a plurality of carbon dioxide indicators. Alternatively, it is possible that each carbon dioxide indicator is associated with a corresponding volume indicator, such that in use, if the liquid volume can be determined using the associated volume indicator, the concentration or amount of carbon dioxide can be determined using one of the carbon dioxide indicators.

[0060] By providing multiple associated carbon dioxide and volume indicators, the amount / concentration of carbon dioxide can be indicated over a wide range of sample volumes. Therefore, users have greater flexibility in choosing the volume of sample liquid to use when performing measurements.

[0061] In some embodiments, the container includes a surface that contacts the liquid sample, the surface being associated with the one or each carbon dioxide indicator and volume indicator.

[0062] In use, the volume of the liquid sample can be determined based on the position of the liquid interface relative to at least one of these volume indicators.

[0063] A liquid interface is the interface between a liquid and another substance. This other substance may have a different density than the fluid. The other substance may be a lower-density substance, such as a gas (e.g., carbon dioxide) in the headspace of a container. In embodiments where the liquid interface is defined by a fluid meniscus, the liquid sample is determined based on the location of the peaks or valleys of the meniscus. In these embodiments, a line perpendicular to a plane parallel to the liquid interface is a line perpendicular to a plane tangent to the peaks or valleys of the meniscus.

[0064] In some embodiments where the container is partially defined by a movable wall (e.g., a piston), the liquid interface is the interface between the liquid and the movable wall—for example, in some embodiments where the container is defined by a syringe barrel and a piston inside the barrel (which moves to change the volume of the container).

[0065] In some embodiments, the surface is the inner surface of the container wall (e.g., the inner surface of the syringe body).

[0066] Carbon dioxide and volume indicators can be disposed on the surface of a container. A body can define the surface, and the body has the carbon dioxide and volume indicators, which are visible through the surface. The carbon dioxide and volume indicators can be etched or printed, for example, printed or etched onto the surface. The carbon dioxide and volume indicators can be disposed on different surfaces (e.g., membranes), and thus, these different surfaces are disposed on (e.g., attached to) that surface. Therefore, the carbon dioxide and volume indicators are associated with a surface, whether they are disposed directly on the surface, on another surface of the body defining the surface in contact with the fluid, or on a different body attached to or otherwise disposed on a surface. Importantly, the intersection between the carbon dioxide and volume indicators, along with the liquid interface and the surface in contact with the liquid, is visible.

[0067] It is possible that the volume indicators are arranged along a reference line. Alternatively, it is possible that each carbon dioxide indicator is arranged above or below the corresponding volume indicator along a first direction, wherein the first direction is perpendicular to a plane parallel to the liquid interface, and wherein the reference line is defined by the intersection between the plane parallel to the liquid interface and the surface.

[0068] A reference line can be defined by the intersection between a plane of the liquid interface (e.g., a plane that intersects the peak or valley of the meniscus of the liquid interface and is parallel to the liquid interface) and the surface. The reference line is typically perpendicular to the longitudinal axis of the container.

[0069] Typically, the first reference line is not marked on the surface (i.e., it is an imaginary line), and this first reference line is defined to aid in describing the inventive subject matter included herein. Typically, the first direction is aligned with the direction of gravity (i.e., vertical), and the plane parallel to the interface is transverse to the first direction (i.e., horizontal).

[0070] It is possible that the measuring device further includes a volume indicator for visually indicating the volume of the liquid sample, wherein the container includes a surface associated with the volume indicator. In use, the volume of the liquid sample can be determined based on the position of the liquid interface relative to the volume indicator.

[0071] In some embodiments, the or each volume indicator includes a measurement line marking at least a first point and a second point;

[0072] In practice, the volume of the liquid sample can be determined based on the position of the liquid interface relative to the first and second points.

[0073] The measurement line between the first point and the second point has a gradient relative to the first direction and the reference line;

[0074] The first direction is perpendicular to the plane parallel to the liquid interface;

[0075] The reference line is defined by the intersection of a plane parallel to the liquid interface and a surface.

[0076] Among them, the first point and the second point are offset from each other along the first direction;

[0077] The first and second intersection points are offset from each other along the reference line;

[0078] Wherein, the first intersection point is the point closest to the first point where the first intersecting plane intersects the reference line, and the second intersection point is the point closest to the second point where the second intersecting plane intersects the reference line; and

[0079] The first intersecting plane passes through the first point and is perpendicular to the first tangent line of the surface at the first point; the second intersecting plane passes through the second point and is perpendicular to the second tangent line of the surface at the second point; and the first and second tangent lines are parallel to a plane parallel to the liquid interface.

[0080] By measuring the volume of a liquid sample using the measuring line defined above, particularly accurate measurement results can be obtained. Conventional volume measuring devices (e.g., conventional graduated cylinders) have graduations defined along a measuring line (i.e., typically vertically) perpendicular to a plane parallel to the liquid interface. The inventors have recognized that by orienting the measuring line at an angle away from the vertical direction, the same range of liquid volume can be extended along a measuring line of a longer length than that of a conventional measuring container (assuming the containers being compared have the same shape and size). Compared to a vertically oriented measuring line, this allows for a greater number of measuring marks to be placed on the line for a given vertical distance without making the marks so closely spaced that it is difficult or even impossible to accurately read the measurement results. Thus, similar fluid levels can be distinguished more reliably.

[0081] In use, the liquid volume can be determined based on the position of the liquid level relative to points along the measuring line, each point indicating a predetermined volume. The surface typically extends over the liquid interface. The liquid interface is typically located in a first direction between the first point and the second point.

[0082] The measuring line can be disposed on the surface of the container. The body can define the surface, and the measuring line is visible through the surface. The measuring line can be etched or printed, for example, the measuring line can be printed or etched onto the surface. The measuring line can be disposed on a different surface (such as a membrane), thus the different surface is attached to the measuring line. Therefore, the measuring line is associated with a surface, whether the measuring line is disposed directly on the surface, on another surface of the body defining the surface in contact with the fluid, or on a different body to which a surface is attached or otherwise disposed. Importantly, the intersection of the measuring line, along with the fluid interface and the surface in contact with the liquid, is visible.

[0083] The measuring line may include a continuous line extending between at least the first point and the second point. In other words, the measuring line may extend continuously between the first point and the second point.

[0084] The first point and / or the second point can be a point along a measurement line. In other words, the first point and / or the second point can each be spaced apart from an end of the measurement line. In other embodiments, the first point and / or the second point can each be an end of the measurement line. For example, the first point can be one end of the line defining the measurement line, and the second point can be the other end of the line defining the measurement line. In some embodiments, the first point and / or the second point can be associated with markings (e.g., markings that visually indicate a predetermined volume). For example, each marking can be a numerical label.

[0085] The liquid interface can be located between the first point and the second point; that is, the liquid interface can appear to intersect the measurement line between the first point and the second point. Therefore, the relative distances between the intersection of the liquid interface and the first point, and between the intersection of the liquid interface and the second point, can be used to allow for particularly precise determination of the liquid volume between the volume associated with the first point and the volume associated with the second point.

[0086] As defined above, the first and second points are offset from each other. The gradient of the measurement line is defined using the relative interval between the first and second points along a first reference line and a first direction. The first direction, together with the reference line, effectively provides a coordinate system that can be used to define the gradient of the measurement line associated with the surface in contact with the liquid, regardless of the surface topography. In effect, the coordinate system allows the measurement line to be mapped to the manifold associated with the surface.

[0087] It is possible that the measuring device further includes an additional surface movably attached to the surface, wherein the additional surface causes the volume indicator or each volume indicator to be disposed thereon, and optionally causes the carbon dioxide indicator or each carbon dioxide indicator to be disposed thereon.

[0088] By placing concentration and / or volume indicators on an additional surface that is movably attached to the surface in contact with the liquid, the user can more easily observe the measuring device along the appropriate viewing direction (i.e., along the line of sight along which the relevant indicators are visible and / or where a more accurate reading can be obtained), thereby facilitating convenient and accurate measurements. For example, when the volume indicator includes a measuring line, particularly accurate readings can be obtained along a line of sight that coincides with the viewing plane perpendicular to the liquid interface and with the normal to the surface at the relevant point along the measuring line.

[0089] For example, users positioned so that they cannot view the device along a proper line of sight can move the additional surface instead of changing their own position or repositioning the device as a whole. In some embodiments, the additional surface may be rotatably mounted relative to a surface in contact with the liquid. The additional surface may be part of a sleeve arranged to rotate about a container holding a liquid sample. For example, both the container and the sleeve may be cylindrical and concentrically arranged. In some embodiments, the additional surface may be slidable relative to a surface in contact with the fluid.

[0090] It is possible that the measuring device further includes a first stop mechanism for preventing the container volume from increasing relative to a first predetermined volume. Alternatively or additionally, it is possible that the measuring device further includes a second stop mechanism for preventing the container volume from decreasing relative to a second predetermined volume.

[0091] By providing a stop mechanism to prevent the container volume from increasing relative to a first predetermined volume, the container can more easily receive liquid samples with a predetermined volume, thereby making the equipment easier to operate.

[0092] In some embodiments, in addition to the first stop mechanism, the device further includes an inlet for receiving a liquid sample into the container and an outlet for allowing the liquid to leave the container when it is received into the container. Thus, the liquid sample can be received into the container under pressure (to prevent dissolved carbon dioxide from being released from the liquid when it is received into the container).

[0093] By providing a stop mechanism to prevent the container volume from decreasing relative to a second predetermined volume, the interior of the container can be kept under negative pressure, thereby allowing for easier measurement of liquids with relatively low levels of dissolved carbon dioxide.

[0094] It is possible that the first stop mechanism is configured to fix the container volume to a first predetermined volume. It is also possible that the second stop mechanism is configured to fix the container volume to a second predetermined volume.

[0095] It should be understood that each stop mechanism or the stop mechanism is a releasable stop mechanism (i.e., any stop mechanism can be temporarily disabled, allowing the volume of the container to be increased and decreased).

[0096] The or each stop mechanism can be a mechanical stop. For example, the or each stop mechanism can include a button-operated, resiliently biased (e.g., using a spring) pin. The or each stop mechanism can also be an electromechanical stop, such as a solenoid having movement of a control pin.

[0097] It is possible that the measuring device further includes a stirrer for agitating the liquid sample. The stirrer can be a mechanical stirrer (e.g., a mixer). The stirrer can be an electrical stirrer (e.g., an electrode for electrolyzing the liquid sample). In other words, it should be understood that a stirrer is essentially any means used to promote the carbon dissolved in the liquid sample to reach equilibrium faster than if the container were not agitated.

[0098] By providing a stirrer, liquid samples can be stirred more easily and with a greater degree of control.

[0099] It is possible that the measuring device further includes: a processor configured to determine an indication of the amount or concentration of carbon dioxide dissolved in the liquid; and / or optionally a sensor for sensing the volume of the container.

[0100] The processor can be configured to perform calculations and / or use lookup tables to determine an indication of the amount or concentration of carbon dioxide dissolved in a liquid.

[0101] The device may further include a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium) that stores instructions which, when executed by a processor, cause the processor to perform as described herein. The processor may be one or more processors.

[0102] It should be understood that sensors used to sense container volume can sense parameters related to the container volume, rather than directly sensing the volume. For example, in some embodiments where the container is defined by a piston and a syringe barrel, a volume sensor can be used to sense the position of the piston (e.g., the displacement of the piston relative to a first piston position corresponding to a 0 ml container volume). In some embodiments, a volume sensor is used to sense the volume of the container (or a volume-related parameter) when a liquid sample (e.g., through a container inlet) is received into the container, such that the volume of the liquid sample can be automatically determined. Additionally or alternatively, a volume sensor is used to sense a second volume (or a parameter related to a second volume).

[0103] Sensors used to sense the volume of a container can use capacitive sensing (for example, the sensor could be a capacitive touch slider).

[0104] In some embodiments, the measuring device includes a user interface configured to receive input, wherein a processor is configured to use the input received by the user interface and determine the concentration based on the input. In some embodiments, the input corresponds to the liquid volume. It is possible that the input corresponds to the liquid type (e.g., beer).

[0105] In some embodiments, the measuring device includes a data storage device for recording the sensed measurement results and / or determination results (or any intermediate determination results) of the concentration / amount of carbon dioxide. In some embodiments, the measuring device includes an output terminal (e.g., a port or wireless transmitter) for outputting the stored data.

[0106] According to another aspect of the present invention, a measuring device is provided for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the measuring device comprising:

[0107] processor;

[0108] A container for holding liquid samples, the container having a variable volume;

[0109] Sensors used to sense the volume of containers; and

[0110] The processor is configured to determine an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the volume of the container measured by the sensor.

[0111] It is possible that the measuring device may further include:

[0112] A temperature sensor configured to sense the temperature of a sample; and / or

[0113] A pressure sensor configured to sense atmospheric pressure, and / or

[0114] The measuring device is configured to receive a predetermined volume of liquid into the container.

[0115] By receiving a predetermined volume of liquid into the container, one less volume measurement is required, thus making the measurement easier to perform. Combining temperature and / or pressure sensors provides more information for a more accurate determination of the concentration or amount of carbon dioxide. In some embodiments, pressure and temperature measurements can be provided as outputs from the measuring device (e.g., visually displayed). In use, pressure and temperature measurements can be used to improve the accuracy of carbon dioxide determination.

[0116] In some embodiments involving a processor, the processor is configured to receive sensed temperature and / or pressure as input and use the sensed temperature and / or pressure measurements to determine an indication of the amount or concentration of dissolved carbon dioxide in the liquid, thereby providing a more accurate measurement of dissolved carbon dioxide.

[0117] According to another aspect of the present invention, a method is provided for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the method comprising:

[0118] Receive input data indicating the second volume of a fluid-impermeable container holding a liquid sample containing dissolved carbon dioxide; and

[0119] An indication of the amount or concentration of carbon dioxide dissolved in the liquid, based on this second volume;

[0120] The second volume is the volume associated with the equilibrium state, and the volume of the container has been allowed to change toward the second volume during agitation of the liquid sample; and

[0121] In this equilibrium state, the pressure in the headspace of the container is equal to the pressure of the surrounding environment, and the carbon dioxide dissolved in the liquid is in chemical equilibrium with the carbon dioxide in the headspace volume.

[0122] According to another aspect of the invention, there exists a processor configured to perform the method just mentioned above.

[0123] According to another aspect of the invention, a computer program product is provided, comprising instructions that, when executed on a computer processing device, cause the computer processing device to perform any of the methods discussed herein for determining an amount or concentration of carbon dioxide dissolved in a liquid. The computer processing device may include a processor (or one or more processors) and a computer-readable storage device, each as described above.

[0124] According to other aspects of the invention, any of the above-described methods or apparatus can be used to determine an indication of the amount or concentration of a gas dissolved in a liquid. That is, the concentration / amount of gases other than carbon dioxide can be determined.

[0125] For example, according to one aspect of the invention, there is a method for determining an indication of the amount or concentration of a gas dissolved in a liquid, the method comprising:

[0126] Provide a fluid-impermeable container for containing a liquid sample, the liquid sample having the gas dissolved therein;

[0127] The liquid sample is stirred while allowing the volume of the container to change from a first volume toward a second volume associated with the equilibrium state;

[0128] In this equilibrium state, the pressure in the headspace of the container is equal to the pressure of the surrounding environment, and the gas dissolved in the liquid sample is in chemical equilibrium with the gas in the headspace volume; and

[0129] This second volume serves as an indication to determine the amount or concentration of gas dissolved in the liquid. Attached Figure Description

[0130] Exemplary embodiments of the present invention will now be illustrated with reference to the following accompanying drawings, in which:

[0131] Figures 1 to 2 This is a schematic diagram of an apparatus for determining the concentration or amount of dissolved carbon dioxide in a liquid according to an embodiment of the present invention;

[0132] Figure 3 This is a schematic diagram of a part of a device according to an embodiment of the present invention;

[0133] Figures 4 to 7 This is a schematic diagram of a device according to an embodiment of the present invention; and

[0134] Figure 8 This is a flowchart illustrating a method for determining the carbonation of a liquid according to an embodiment of the present invention. Detailed Implementation

[0135] Figure 1 and Figure 2 This is a schematic diagram of a measuring device 100 used to determine the amount or concentration of carbon dioxide dissolved in a liquid. Each measuring device includes a container 101 for holding a liquid sample. The container is defined by a syringe barrel 103 and a plunger 105. The plunger 105 is movable relative to the syringe barrel 103, thereby allowing changes in container volume. The measuring device also includes a volume indicator 107 and a carbon dioxide indicator 109.

[0136] In use, fluid can be introduced into container 101 via valve 111 through inlet 113 until the fluid interface reaches the level marked by volume indicator 107. Valve 111 can then be closed to seal container 101. It should be understood that the valve is configured to open and close selectively. The plunger can move relative to syringe barrel 103 toward a second volume associated with an equilibrium state during agitation of the liquid (e.g., shaking of a syringe). The carbon dioxide indicator provides an indication of the amount of carbon dioxide dissolved in the liquid based on the second volume (i.e., based on the position of plunger 104 relative to syringe barrel 103) and the volume of the liquid sample marked by volume indicator 107.

[0137] exist Figure 1 In the illustrated embodiment, the volume indicator includes a line corresponding to a predetermined liquid sample level. In use, for a liquid sample whose volume corresponds to a level greater than or equal to that set by the volume indicator 107, the plunger position below the carbon dioxide indicator 109 indicates that the liquid's carbonation is below a predetermined level corresponding to the carbon dioxide indicator 109. Similarly, for a liquid sample whose volume corresponds to a level less than or equal to that set by the volume indicator 107, the plunger position above the carbon dioxide indicator 109 indicates that the liquid's carbonation is above a predetermined level corresponding to the carbon dioxide indicator 109.

[0138] In addition to the differences noted below, Figure 2 The embodiments shown are similar in form and operation to Figure 1The illustrated embodiments are substantially similar. The volume indicator 107 includes measuring lines marking at least a first point 117 and a second point 119. In use, container 101 contains fluid 110. The fluid 110 within container 101 defines a fluid interface 115. The volume of the liquid sample can be determined based on the position of the fluid interface 115 relative to the first point 117 and the second point 119. In this embodiment, the carbon dioxide indicator includes a graduated scale, wherein the scale marks a range of carbon dioxide amounts based on a volume of liquid sample within the area covered by the volume indicator. In use, for a liquid sample with a volume within the area covered by the volume indicator (e.g., a liquid interface 15 that appears to intersect the measuring lines between (or at) the first and second points 117 and 119), the amount of carbon dioxide dissolved in the liquid sample can be determined based on the position of the plunger 105 relative to the graduated scale of the carbon dioxide indicator 109.

[0139] Figure 3 It shows Figure 2 Volume indicator 107. Figure 3 A first direction 123 and a reference line 121 are shown. The first direction 123 is perpendicular to a plane parallel to the fluid interface 115. The reference line 121 is defined by the intersection between the plane parallel to the fluid interface 115 and the surface 102 of the syringe barrel 103. The measurement line between the first point 117 and the second point 119 has a gradient relative to the first direction 123 and the reference line 121.

[0140] Figure 4 This is a schematic diagram of a measuring device 200 used to determine the amount or concentration of carbon dioxide dissolved in a liquid. The measuring device includes a container 201 defined by a syringe barrel 203 and a plunger 205, wherein the plunger 205 is movable relative to the syringe barrel 203 to allow for changes in container volume.

[0141] The measuring device includes multiple volume indicators 207a to 207e and multiple carbon dioxide indicators 209a to 209e. Each volume indicator 207a to 207e is associated with a corresponding carbon dioxide indicator 209a to 209e. That is, in use, if the liquid volume of the sample is within the volume range indicated by volume indicator 207a, the corresponding carbon dioxide indicator 207a can be used to determine the amount of carbon dioxide dissolved in the liquid. The carbon dioxide indicators 209a to 209e are arranged around the syringe barrel 203 such that each carbon dioxide indicator is marked above the corresponding volume indicator. In this embodiment, the multiple volume indicators 207a to 207e are portions of a continuous measuring line. It should be understood that in other embodiments, each volume indicator 207a to 207e may be a separate line parallel to the fluid interface, for example, to indicate a predetermined liquid sample volume.

[0142] Despite Figure 4 Not shown, but at least a subset of the scales of carbon dioxide indicators 209a to 209e are marked with numerical indications of the amount / concentration of dissolved carbon dioxide. These numerical indications are typically calculated for a predetermined temperature (e.g., 25°C) and atmospheric pressure. In practice, corrections (e.g., using a correction table) may be applied after the initial indication of dissolved carbon dioxide is determined to account for any variation between the actual temperature and the predetermined temperature and / or any variation between the actual pressure and atmospheric pressure.

[0143] Figure 5 This is a schematic diagram of a measuring device 300 having a container 301 defined by a syringe barrel 303 and a plunger 305. The measuring device 300 includes an inlet 313 leading to the container 301 and a valve for sealing the container 301. The measuring device 300 also includes a volume indicator 309 and a display 327 (i.e., a carbon dioxide indicator) for providing an indication of the concentration / amount of dissolved carbon dioxide. The display 327 is attached to the container 301 via a housing 325. The housing 325 houses a processor 329 and supports a user interface 330. The measuring device 300 also includes a position sensor 331 for sensing the position of the plunger 305. The device further includes a temperature sensor for sensing the temperature of a liquid sample within the container 301 and a pressure sensor for sensing the pressure of the environment surrounding the container.

[0144] In use, the user can open valve 311 and draw a certain volume of liquid into container 301 through input 313. Container 301 is then sealed by closing valve 311. The user can then measure the volume of the liquid sample using volume indicator 309. The volume of the liquid sample can be received as input to processor 329 via user interface 330. The sample liquid in container 301 can be agitated, allowing changes in the volume of container 301 (e.g., allowing plunger 305 to move relative to syringe barrel 303). When the pressure inside container 301 equalizes with the ambient pressure, plunger 305 will come to rest. Processor 329 is configured to receive the sensed position of plunger 305 at this stable point as input. The measured temperature of the liquid sample and the pressure of the ambient environment are measured by corresponding sensors. Processor 329 is also configured to receive sensed temperature and pressure data as input.

[0145] The processor 329 is configured to determine the amount of carbon dioxide dissolved in the liquid sample based on the measured volume of the liquid sample, the plunger position at equilibrium, the sensed temperature of the liquid sample, and the sensed pressure of the surrounding environment. The determined amount is then displayed on the display 327.

[0146] Figure 6 This is a schematic diagram of measuring device 400. Apart from the differences noted below, Figure 6 The measuring device 400 shown is similar to Figure 5 The measuring device 300 shown. Figure 6 The measuring device 400 shown also has a container 401 defined by a syringe barrel 403 and a plunger 405. The measuring device 400 includes an inlet 413 leading to the container 401 and a valve 411 for sealing the container 401. The measuring device 400 includes a display 427 (i.e., a carbon dioxide indicator) for providing an indication of the concentration / amount of dissolved carbon dioxide. The display 427 is attached to the container 401 via a housing 425, wherein the housing 425 houses a processor 429. The measuring device 400 also includes a position sensor 431 for sensing the position of the plunger 405, a temperature sensor for sensing the temperature of the liquid sample within the container 401, and a pressure sensor for sensing the pressure of the environment surrounding the container.

[0147] Figure 6 The measuring device 400 shown is Figure 5 The main difference between the measuring devices 300 shown is that measuring device 400 includes an outlet from container 414 and a second valve 412, and does not have a user interface 330. Instead of a user interface, a position sensor is further configured to measure the position of plunger 405 when a liquid sample is received into container 401. In use, when a liquid sample is received under pressure, the plunger position is fixed (so that no gas escapes from the liquid before agitation). Liquid is received via valve 411 through inlet 413 and is allowed to flow out of container 401 through outlet 414 and valve 412. Once a liquid sample is received, valves 411, 412 can be closed to seal container 401. Processor 429 is configured to receive the plunger position corresponding to the plunger position when the liquid sample is received.

[0148] Figure 7 This is a schematic diagram of a measuring device 500 having a container 501 for containing a liquid sample. The container 501 has a variable volume and is attached to a base 543 via a support 539. The device 500 can be held in place using a handle 541. The measuring device 500 includes an inlet 513 leading to the container 501, an outlet 514 exiting the container, and valves 511, 512. The measuring device 500 further includes a display 527 attached to the container 501 via a housing 533 for providing an indication of the concentration / amount of dissolved carbon dioxide. The measuring device 500 has a volume sensor 531 for sensing the volume of the container 501. The volume sensor 531 is a capacitive touch slider. The housing 533 houses a processor. The sensed data / measurement results are transmitted from the sensor via a cable 545.

[0149] The measuring device further includes a mechanical stop mechanism 537 for fixing the volume of the container in a first volume to receive a liquid sample in cooperation with a capacitive slider 531. In this embodiment, the stop mechanism is positioned between the base 543 and the container 501. In other embodiments, the stop mechanism may be repositioned on the opposite side of the container 501 (and next to the volume sensor 531).

[0150] Figure 8 This is a flowchart illustrating method 600 for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid. Method 600 includes step 610 of providing an impermeable container holding a sample of carbonic acid in a liquid. Method 600 also includes an agitation step 620: agitating the liquid sample while allowing a change in the volume of the container. The volume of the container is allowed to change toward a second volume corresponding to an equilibrium state, for example, where the pressure in the headspace within the container is equal to the pressure of the environment surrounding the container, and the carbon dioxide dissolved in the liquid sample is in chemical equilibrium with the carbon dioxide in the headspace volume. Typically, agitation is achieved by shaking the container, although other methods (e.g., stirring and electrolysis) are also possible as described above. In determination step 630, an indication of the amount or concentration of carbon dioxide dissolved in the liquid is determined (e.g., calculated) based on the second volume.

[0151] In summary, a method (600) is provided for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid. The method includes the step of providing a fluid-impermeable container (610) containing a liquid sample having carbon dioxide dissolved therein. The method also involves agitating the liquid sample while allowing the volume of the container to change from a first volume towards a second volume associated with an equilibrium state (620). In the equilibrium state, the pressure in the headspace within the container is equal to the pressure of the environment surrounding the container, and the carbon dioxide dissolved in the liquid sample is in chemical equilibrium with the carbon dioxide in the headspace volume. The method further includes the step of determining an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume (630). The invention also relates to a method of manufacturing an apparatus for performing these methods, and the apparatus itself.

[0152] In the specification portion and claims of this specification, the words “comprising” and “containing,” and variations thereof, mean “including but not limited to,” and are not intended to exclude, other components, integrals, or steps. Throughout the specification portion and claims of this specification, the singular encompasses the plural unless the context requires otherwise. In particular, where the indefinite article is used, this specification should be understood to consider both the plural and singular forms unless the context requires otherwise.

[0153] Features, elements, characteristics, or groups described in conjunction with specific aspects, embodiments, or examples of the invention should be understood to be applicable to any other aspect, embodiment, or example described herein, unless incompatible therewith. All features disclosed in this specification (including any appended claims, abstract, and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except where at least some of such features and / or steps are mutually exclusive combinations. The invention is not limited to the details of any of the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification (including any appended claims, abstract, and drawings) or to any novel step or any novel combination of steps of any disclosed method or process.

Claims

1. A method for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the method comprising: Provides an impermeable container for holding a liquid sample containing dissolved carbon dioxide; The liquid sample is agitated while allowing the volume of the container to change from a first volume toward a second volume associated with an equilibrium state; In the equilibrium state, the pressure in the headspace inside the container is equal to the pressure of the surrounding environment, and the carbon dioxide dissolved in the liquid sample is in chemical equilibrium with the carbon dioxide in the headspace volume. as well as An indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume.

2. The method according to claim 1, wherein, The step of determining the amount or concentration of carbon dioxide dissolved in the liquid is also based on the volume of the liquid sample, and optionally... The step of determining the amount or concentration of carbon dioxide dissolved in the liquid is based on the ratio of the difference between the second volume and the volume of the liquid sample to the volume of the liquid sample, and / or optionally... The step of determining the amount or concentration of carbon dioxide dissolved in the liquid is not based on any volume other than the volume of the sample liquid and the second volume.

3. The method according to claim 1 or 2, wherein, The step of determining the amount or concentration of carbon dioxide dissolved in the liquid is further based on the partial pressure of a second gas present in the top space of the container, and optionally wherein the second gas is water vapor.

4. The method according to any of the preceding claims, wherein, The step of determining the amount or concentration of carbon dioxide dissolved in the liquid is further based on pressure measurements and / or temperature measurements, and optionally, the temperature measurements are the temperature of the liquid.

5. The method according to any of the preceding claims, wherein, The liquid sample has an initial concentration and / or initial amount of carbon dioxide dissolved therein, wherein determining the amount or concentration of carbon dioxide dissolved in the liquid includes determining the initial concentration or the initial amount, respectively.

6. The method according to any of the preceding claims, wherein, The step of determining the amount or concentration of carbon dioxide dissolved in the liquid includes: To obtain a first value for the amount or concentration of the carbon dioxide dissolved in the liquid; and The adjusted value of the amount or concentration of carbon dioxide dissolved in the liquid is obtained based on the measured temperature and / or measured pressure.

7. A method for manufacturing a measuring device for performing the method according to any preceding claim, the method comprising: Provide the container for containing the liquid sample; as well as A carbon dioxide indicator is provided, the carbon dioxide indicator being used to indicate the concentration or amount of carbon dioxide dissolved in the liquid based on the second volume, and / or A sensor for sensing the volume of a container and a processor configured to receive the output from the sensor as input are provided.

8. A measuring device for determining the amount or concentration of carbon dioxide dissolved in a liquid, the measuring device comprising: A container for holding liquid samples, the container having a variable volume; First carbon dioxide indicator; In use, the container defines a closed system that is capable of progressing toward satisfying a first equilibrium condition and a second equilibrium condition. Wherein, the first equilibrium condition corresponds to the pressure in the headspace inside the container being equal to the pressure of the environment surrounding the container, and the second equilibrium condition corresponds to the carbon dioxide dissolved in the liquid sample being in chemical equilibrium with the carbon dioxide in the headspace volume; The volume of the container can be changed toward a second volume that is at least associated with the first equilibrium condition; and The first carbon dioxide indicator is configured to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume after the closed system has progressed toward satisfying the first and second equilibrium conditions.

9. The measuring device according to claim 8, wherein, During use, while the liquid sample is stirred, the volume of the container can change towards the second volume, and The second volume is associated with the first equilibrium condition and the second equilibrium condition.

10. The measuring device according to claim 8 or 9, wherein, The first carbon dioxide indicator is configured to provide an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the volume of the liquid sample and optionally based on the ratio of the difference between the second volume and the volume of the sample liquid to the volume of the sample liquid.

11. The measuring device according to any one of claims 8 to 10, in, The first carbon dioxide indicator visually indicates the amount or concentration of carbon dioxide dissolved in the liquid. The measuring device further includes a first volume indicator for visually indicating the volume of the liquid sample, and The first volume indicator is associated with the first carbon dioxide indicator such that, in use, if the volume of the liquid sample can be determined using the first volume indicator, the concentration or amount of carbon dioxide can also be determined using the first carbon dioxide indicator.

12. The measuring device according to claim 11, in, The first volume indicator is one of a plurality of volume indicators, and the first carbon dioxide indicator is one of a plurality of carbon dioxide indicators. Each carbon dioxide indicator is associated with a corresponding volume indicator, such that in use, if the volume of the liquid can be determined using the associated volume indicator, the concentration or amount of carbon dioxide can be determined using one of the carbon dioxide indicators.

13. The measuring device according to claim 11 or 12, in, The container includes a surface that contacts the liquid sample, and the surface is associated with each or every carbon dioxide indicator and volume indicator. In use, the volume of the liquid sample can be determined based on the position of the liquid interface relative to at least one of the volume indicators.

14. The measuring device according to claim 13 when dependent on claim 12, in, The volume indicator is arranged along the reference line. Each carbon dioxide indicator is arranged above or below the corresponding volume indicator along a first direction. Wherein, the first direction is perpendicular to the plane parallel to the liquid interface, and The reference line is defined by the intersection between the plane parallel to the liquid interface and the surface.

15. The measuring device according to any one of claims 8 to 10, in, The measuring device further includes a volume indicator for visually indicating the volume of the liquid sample. The container includes a surface associated with the volume indicator. In use, the volume of the liquid sample can be determined based on the position of the liquid interface relative to the volume indicator.

16. The measuring device according to any one of claims 11 to 15, in, Each volume indicator includes a measurement line that marks at least a first point and a second point; In practice, the volume of the liquid sample can be determined based on the position of the liquid interface relative to the first point and the second point. The measurement line between the first point and the second point has a gradient relative to the first direction and the reference line; Wherein, the first direction is perpendicular to the plane parallel to the liquid interface; The reference line is defined by the intersection between the plane parallel to the liquid interface and the surface; Wherein, the first point and the second point are offset from each other along the first direction; The first intersection point and the second intersection point are offset from each other along the reference line; Wherein, the first intersection point is the point closest to the first point where the first intersecting plane intersects the reference line, and the second intersection point is the point closest to the second point where the second intersecting plane intersects the reference line; and Wherein, the first intersecting plane passes through the first point and is perpendicular to the first tangent line of the surface at the first point, and the second intersecting plane passes through the second point and is perpendicular to the second tangent line of the surface at the second point, wherein the first tangent line and the second tangent line are parallel to the plane parallel to the liquid interface.

17. The measuring device according to any one of claims 11 to 16, further comprising an additional surface movably attached to said surface, wherein, The additional surface allows one or each volume indicator to be disposed thereon, and optionally allows one or each carbon dioxide indicator to be disposed thereon.

18. The measuring device according to any one of claims 8 to 17, further comprising a first stop mechanism for preventing the container volume from increasing relative to a first predetermined volume and / or a second stop mechanism for preventing the container volume from decreasing relative to a second predetermined volume.

19. The measuring apparatus according to any one of claims 8 to 18, further comprising a stirrer for agitating the liquid sample.

20. The measuring apparatus according to any one of claims 8 to 19, further comprising: A processor configured to determine an indication of the amount or concentration of carbon dioxide dissolved in the liquid; And / or optionally, a sensor for sensing the container volume.

21. A measuring device for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the measuring device comprising: processor; A container for holding liquid samples, the container having a variable volume; Sensors used to sense the volume of containers; and The processor is configured to determine an indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the container volume measured by the sensor.

22. The measuring apparatus according to any one of claims 8 to 21, further comprising: A temperature sensor configured to sense the temperature of the sample; and / or A pressure sensor configured to sense atmospheric pressure, and / or The measuring device is configured to receive a predetermined volume of liquid into the container.

23. A method for determining an indication of the amount or concentration of carbon dioxide dissolved in a liquid, the method comprising: Receive input data indicating a second volume of an impermeable container holding a liquid sample containing dissolved carbon dioxide; as well as An indication of the amount or concentration of carbon dioxide dissolved in the liquid based on the second volume; Wherein, the second volume is the volume associated with an equilibrium state, and the volume of the container has been permitted to change toward the second volume during agitation of the liquid sample; and In the equilibrium state, the pressure in the top space inside the container is equal to the pressure of the surrounding environment, and the carbon dioxide dissolved in the liquid is in chemical equilibrium with the carbon dioxide in the top space volume.

24. A processor configured to perform the method of claim 23.

25. A computer program product comprising instructions that, when executed on a computer processing device, cause the computer processing device to perform the method as claimed in any one of claims 1 to 6 or 23.

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