Apparatus and method for measuring a top space volume of a container

Abstract

In an apparatus for measuring a top space volume (VOLkopf) of a container above a liquid, there is, in the top space volume, an overpressure of either a gas contained in the liquid or a protective gas and for measuring the content of one or more gases to be measured, said one or more gases being contained in the top space, comprising a measuring chamber that can be placed in a gas-tight manner on the container having a defined volume (VOLgesamt), which measuring chamber contains a perforation device, and comprising a measuring device for determining at least one gas to be measured, said gas being contained in the top space of the container, wherein the measuring chamber is coupled to an expansion chamber having a first connecting element that can be closed in a gas-tight manner, the expansion chamber is coupled to at least one flushing and cleaning apparatus via gas-tight connecting elements, the measuring chamber, the connecting element and the expansion chamber have defined, constant volumes (VOL1, VOL2) at a predefined temperature (T), and at least one sensor element and an evaluation unit are provided for determining the top space volume (VOLkopf) and the content of at least one gas contained in the top space. A method is also proposed.

Description

[0001] DEVICE AND METHOD FOR MEASURING A HEAD SPACE VOLUME OF A

[0002] CONTAINER

[0003] The present invention relates to a device for measuring a headspace volume of a container above a liquid, wherein an overpressure of either a gas contained in the liquid, such as CO2, or a protective gas, such as N2, is present in the headspace volume, as well as for measuring the content of one or more gases to be measured contained in the headspace, comprising a measuring chamber that can be placed gas-tight on the container having a defined volume, which measuring chamber contains a perforation device, preferably a hollow needle, and a measuring device for determining at least the gas to be measured contained in the headspace of the container, preferably oxygen, as well as a method for measuring a headspace volume of a container of a liquid, wherein an overpressure of either a gas contained in the liquid, such as CO2, or a protective gas, such as N2, is present in the headspace volume.and for measuring the content of one or more gases to be measured contained in the headspace with a device for measuring a headspace volume of a container, in which, in a first step, a measuring chamber having a volume is placed gas-tight on a closure or a perforable wall of the container and then the closure or the perforable wall of the container is penetrated with a perforation device, preferably a hollow needle.

[0004] Methods and devices for measuring the oxygen and / or carbon dioxide content in the headspace of liquid containers are known and have long been used to draw conclusions about the shelf life of the contents of the container.

[0005] For example, US 2009 / 0084156 A1 describes a method for efficiently measuring the oxygen content of both the headspace and a fluid within a hermetically sealed container. In the method, the cover or a part of the container is penetrated using a hollow needle and, after forming an opening in the cover or part of the container, a test head is inserted through the hollow needle into the interior of the headspace of the container to measure the oxygen concentration using a fluorescent material applied to the test head. With such a device, the dissolved oxygen content in the food or beverage contained in the container can also be measured by lowering the test head further into the interior of the liquid contained in the container and taking another fluorescence measurement.EP 1 762 837 A2 discloses a device for determining the CO2 concentration in a CO2-containing liquid, which determination is carried out by determining the total content of the gases and the partial pressures of N2 and O2 in a headspace having a predetermined gas volume, deriving the CO2 pressure in the headspace from the total pressure prevailing there and the partial pressures of N2 and O2, and therefrom deriving the CO2 concentration in the liquid volume, wherein the total amount of liquid contained in the container has been predetermined.

[0006] US 5,426,593 describes a device for measuring the oxygen content in a gas contained in a beverage using a degassing device for the liquid, which is connected to a penetration device to first degas the perforated containers and then measure the gases expelled by the degassing device in a separate measuring chamber. EP 3 722 777 A1 describes a method for measuring the oxygen content of the headspace gas in a container. In this method, a cover of the container is penetrated by a hollow needle, the resulting opening is sealed airtight, and the headspace gas located in the headspace of the container is withdrawn by a pump via the sampling tube or hollow needle inserted into the interior of the container, measured in a sensor device, and then pumped back into the container.With such a method, it is possible to measure both the headspace volume of the headspace gas in the container and the oxygen partial pressure in the headspace of the container. Finally, US 3,849,070 shows a device and a method for measuring the oxygen and carbon dioxide content in a liquid contained in a hermetically sealed container. This device can also be used to determine the headspace of the container. A syringe closable with a valve is positioned on the top of the container, penetrates the cover, and, under pressure, volatile components such as CO2 and oxygen are expelled from the top of the container using an inert gas. The CO2 or O2 content in the headspace of the container is measured from this sample.

[0007] From the devices described, it is clear that measuring both the volume of the headspace of a container and the gas content contained therein not only always involves penetrating the container with a hollow needle, but also, in particular, applying pressure to the container to transfer the gases contained in the headspace to a separate measuring device or introducing a measuring device provided in the hollow needle into the headspace or the fluid, which determines the desired measured variables. Such devices are relatively complex and require, in particular, precise equipment and selected pressures to achieve the typically required measurement accuracies of 0.1 ppm.

[0008] With all these measuring devices, it is possible to determine whether, for example, oxygen has been introduced into a hermetically sealed container containing a liquid, usually under pressure, during a filling process or has been introduced into the headspace of the container due to a small leak in the container closure. Information about such an oxygen content in the headspace of a container, particularly a beverage container such as a can, bottle, etc., is of vital interest to manufacturers, as the oxygen content in the headspace has a significant impact on the shelf life and flavor quality of the beverage contained in the container.It is therefore of great importance for both the manufacturer and the consumer to know this oxygen content, which cannot originate from the production process of the beverage per se, and to subsequently minimize it through specific process steps.

[0009] The present invention therefore aims to provide a method and a device with which it is possible to measure both the headspace volume and the content of a specific gas of interest in the headspace of a container, which method provides reproducible results and, in particular, is sufficient without great expenditure on equipment and without the addition of inert gases or the use of pumps or applied overpressures.

[0010] To achieve this object, the device according to the invention is essentially characterized in that the measuring chamber is coupled to an expansion chamber having a first gas-tight sealable connecting element, in that the expansion chamber is coupled to at least one rinsing and cleaning device via gas-tight sealable connecting elements, in that the measuring chamber, the connecting element and the expansion chamber have precisely defined volumes at a predetermined temperature and in that at least one sensor element and an evaluation and computing unit are provided for determining the headspace volume and the content of at least one gas to be measured contained in the headspace. Due to the fact that all elements of the device according to the invention have precisely defined volumes at a predetermined temperature and the device is gas-tightly attached to the container or vessel to be measured.whose closure can be placed, after penetration of the closure or a wall of the container to be examined by means of the perforation device, a pressure equalization takes place between the head space of the container to be examined and the measuring chamber, which is in a gas-tight connection with this measuring chamber immediately after penetration of the closure through the perforation device, which can be designed as a hollow needle, for example. The partial pressure of the gas to be measured, for example the oxygen partial pressure, the total pressure and the temperature in the measuring chamber are now measured in the measuring chamber. In a subsequent step, the expansion chamber is opened by opening the first gas-tight sealable connecting element in order to allow the gas to expand from the head space of the container and the measuring chamber into the expansion chamber. After establishment of an equilibrium orDuring pressure equalization, the prevailing partial pressures, for example, the oxygen partial pressure, the total pressure, and the temperature are measured. Using the known gas equations for ideal gases, p*V - nRT, and knowing the exact volumes, pressures, and temperatures in the measuring chamber, the connecting element, and the expansion chamber, both the volume of the headspace of the container being measured and the partial pressure of the gas being tested in this headspace, for example, the oxygen partial pressure, can be determined. It goes without saying that in order to determine the partial pressure of a specific gas, the entire measuring device must not contain any of the specific gas being tested before being attached to the container being tested.This is typically done by purging the measuring device with an inert gas to remove the specific gas to be analyzed. According to the invention, nitrogen, CO2, or a noble gas can be used as an inert gas.

[0011] In the context of the present invention, a gas of interest or to be analyzed is understood to mean any foreign gas in the container whose headspace volume is being analyzed, which foreign gas can have an adverse effect on the liquids contained in the container. Examples of foreign gases or gases to be analyzed are oxygen, ammonia, sulfur-containing gases, methane, or the like. To simplify the explanation of the invention, oxygen is cited as an example in the following description and the figures as the specific gas to be determined. This is because it is the most important gas to be analyzed, particularly for tests on CO2-containing beverages, since an undesirable oxygen content adversely affects not only the shelf life but also the taste of the beverages being analyzed.However, it is obvious to a person skilled in the art that both the device and the method of the present invention can be applied in the same way to any other gas, e.g. NH3. The only necessary change is replacing the gas sensor or integrating an additional gas sensor. It is also obvious to a person skilled in the art that the terms measuring chamber, expansion chamber and connecting element were chosen to enable easy differentiation of the respective elements. In practice, both the measuring chamber and the expansion chamber represent precisely defined volumes into which the pressurized gas can flow from the headspace to be measured. The arrangement of the chambers can be reversed, and it is also possible for measuring elements to be provided in only one chamber or in both the measuring chamber and the expansion chamber.

[0012] The headspace of a container containing a gas to be examined is usually referred to as headspace in the relevant technical language, which term is either also used here or can at least be used instead of the German term Kopfraum.

[0013] Surprisingly, such a device makes it possible to measure the exact oxygen content in the headspace of the container, as well as the volume of this headspace, by utilizing the overpressure in the container containing the liquid, without the need for any device that transfers the gas contained in the headspace into a measuring device using externally applied pressure, e.g., by pumping. Simply by providing two separable volumes, the measuring chamber and the expansion chamber, each with precisely defined volumes, pressure equalization can be achieved in two steps: 1. penetration and ingress of the gas into the measuring chamber, and 2.By opening the connecting element and allowing the gas to enter the expansion chamber, the pressure between the overpressure prevailing in the headspace of the container to be measured and the pressure prevailing in the measuring chamber and the expansion chamber is measured. Using the known gas equations, both the headspace volume and its oxygen or other gas content are determined using specific sensors. Thus, the present invention makes it possible to obtain precise measurement values ​​using a structurally simple device, which not only allows the method to be carried out more quickly but also, in particular, allows a significantly more cost-effective and simpler device to be provided.In accordance with a further development of the invention, the device is designed in such a way that measuring devices for measuring the concentration of at least one gas to be measured, the pressure, and the temperature are provided in the measuring chamber. This further makes it possible, in comparison to conventional devices, to use only a few measuring devices and yet still obtain precise results quickly and reliably. This is particularly true because, once pressure has equalized between the headspace, the measuring chamber, and the expansion chamber, one measurement in the measuring chamber is sufficient to measure both the pressure difference and the difference between the measured oxygen concentration and the prevailing temperature after the expansion chamber has been opened. Corresponding measurements in the expansion chamber are not required per se, but can of course be carried out for safety reasons.

[0014] By designing the first gas-tight, sealable connecting element as a two-way valve, as corresponds to a further development of the invention, it is ensured that no unnecessary free spaces or volumes are provided or formed between the measuring chamber and the expansion chamber, but rather the required quantities can be measured directly. With such a device, measurement errors are avoided as far as possible, since the entry of foreign gas, for example via a multi-way valve, is reliably prevented and, moreover, since the volume of such a valve is known beyond doubt, it can simply be taken into account in the measurement. Thus, an error due to an increasing volume of the device for measuring a headspace volume or volume of a headspace of a container, in particular one increasing by an unknown amount, is also reliably prevented.In order to ensure during each measurement that no contamination whatsoever can occur in the interior of the measuring chamber, the expansion chamber, or the hollow needle with oxygen or other gaseous molecules to be measured, e.g., NH₄, remaining in the device, the invention is further developed in such a way that the measuring chamber, the expansion chamber, and the perforation device are further connected via a multi-way valve to at least one purging device and to a source of purge gases via a pressure reduction device. With the aid of such a multi-way valve, in a first step before each measurement, the measuring chamber, the expansion chamber, and the hollow needle can be connected to the pressure reduction valve and the purge gas source, and the gas contained in the entire measuring device can be quantitatively removed from it.This measure ensures that the pressure reduction device is also free of any residual gas to be measured, e.g. oxygen or other gases contained in the headspace of the container being measured, and thus measurement errors due to residual gas can be reliably avoided. After several measurements have been carried out, the multi-way valve is switched and the expansion chamber, as well as the first measuring chamber and the hollow needle, are brought into position with the flushing device. The device is then flushed, for example with a cleaning agent, until no residue of the fluid entrained by the headspace gas is present in the entire interior of the container, i.e. the hollow needle, the measuring chamber, and the expansion chamber. Any residues of the gas contained in the headspace volume can be measured and displayed, for example, by the gas sensors located in the measuring chamber.Afterwards, purging with inert gas is carried out again to ensure that, before further measurement of the head space of a container, there is no longer any content of the gases to be measured, e.g. oxygen, in the interior of the device consisting of hollow needle, measuring device, connecting element and expansion chamber. By designing the device in such a way that two purging devices are provided, one of which is coupled to the pressure reduction device, as corresponds to a development of the invention, it is possible not only to carefully supply the measuring and expansion chamber with purge gas and to clean it of oxygen orNot only can CO2 residues or other residual components be cleaned from the liquid being measured, but it can also be ensured at the same time that the pressure reduction device is also free of any residual components of oxygen or other gases contained in the headspace of the volume of the container being measured, thus reliably preventing measurement errors due to residual gas in a measurement. To this end, the preferred procedure is for the first purging device to purge with inert gas, while the second purging device introduces a cleaning solution and pumps it through the device, removing any contaminants that may be present in the interior of the measuring and expansion chamber.

[0015] To reliably rule out any measurement errors, the device is further developed so that the perforation device is encased in a deformable sealing element. This is compressed during the perforation process and forms a gas-tight connection between the container and the measuring device before the container closure is punctured, thereby reliably preventing the ingress of foreign gas from outside before or during the perforation process. Furthermore, this ensures that no foreign gas is present between the area of ​​the container to be pierced, i.e., its closure, and the device, which in turn reliably prevents the ingress of foreign gas before or during the measurement.

[0016] With such a device according to the invention, it is thus possible to obtain precise measurement results in a particularly simple manner, and in particular to obtain measurement results that can be obtained without the use of pumping or pressurizing devices. A key element here is to ensure that all volumes present in the measuring device are precisely calibrated in order to avoid inaccuracies. By applying the known gas laws for ideal gases (p1*VOL1 = p2*VOL2), the container containing a pressurized liquid can thus be measured safely and reliably with regard to the oxygen content in the headspace volume or the headspace volume per se. The application of the ideal gas law is permissible in this case because the process is carried out at low pressure and with very small pressure differences.The amount of substance is constant, and the temperature differences are so small that they can be neglected. p1*VOL1 = p2*VOL2. Taking temperature into account, the following would apply: p1*VOL1 / T1 = p2*VOL2 / T2, where p and T are measured and VOL2 is known and constant.

[0017] Such a method for measuring a headspace volume of a container above a liquid mixed with CO2 or another inert gas and for measuring the content of one or more gases contained in the headspace is carried out according to the invention in several steps:

[0018] To prepare the procedure and after each measurement, a purge with inert gas is carried out. This purge is stopped immediately before the measurement to ensure that the inert purge gas used reaches ambient pressure and that no foreign gases, especially no air, can penetrate into the interior of the measuring and expansion chamber. During this preparatory purge, the concentration of the gases in the measuring and expansion chamber is

[0019] All gases contained in the expansion chamber, with the exception of the purge gas, are measured. The last measured value at the end of the purge is designated as the zero value for the gas being measured. This serves as the basis for subsequent measurements and defines the zero value. This ensures that a zero value determination and zero value adjustment take place before each measurement.

[0020] In a first step of the measuring method, a measuring chamber having a first volume VOL1 is placed gas-tight onto a closure or a perforable wall of the container and then the closure or the perforable wall of the container is penetrated with a perforation device, preferably a hollow needle.The gas to be measured, which is present under pressure in the container, is transferred into the measuring chamber, whereupon the pressure of the gas, the temperature of the gas in an interior of the measuring chamber and the concentration of at least one gas to be measured, preferably an oxygen concentration, are measured in the measuring chamber, the closable connecting element between the measuring chamber and an expansion chamber is opened, the gas to be measured is allowed to expand into the expansion chamber and the pressure of the gas to be measured, the temperature and the O2 concentration in the interior of the measuring chamber and the expansion chamber connected to it via a connecting element are measured again, whereupon the head space volume of the container, the pressure in the container and the partial pressure of the at least one measured gas are calculated in relation to a predetermined ZERO value in a computing and evaluation unit.Because the method is carried out in such a way that the pressurised gas contained in the head space of the container to be measured is allowed to flow into the measuring chamber and subsequently into the expansion chamber without the use of any suction or pressure devices, it is possible to safely and reliably determine both the oxygen content in the head space of a container and the volume of this head space itself without the provision of moving parts such as cylinders and pistons, without additional pressure application by applying suction pressure to suck the head space empty, or by applying pressure to expel the gas contained in the head space. This is achieved solely through precise calibration of the parts used in the method and users of the known gas equations.In this way, it is possible to carry out a large number of measurements both reliably and essentially wear-free, in which the error rate that can be caused by applying too high a suction or extrusion pressure is reliably kept to a minimum.

[0021] To obtain reproducible measurements and, in particular, to reliably avoid any errors due to the presence of the gas to be measured in the device, the method is carried out in such a way that, before each measurement, the interior of the device for measuring the headspace volume is purged with an inert gas. After purging the interior, any content of the at least one gas to be measured that may be present in the interior is used for a zero value correction. A similar purging or cleaning process is performed after each measurement.

[0022] In detail, the procedure can be carried out in such a way that

[0023] 1. that the interior of the device, i.e. the measuring chamber, the expansion chamber, the connecting elements and the hollow needle are purged with an inert gas, e.g. nitrogen or a noble gas, before each measurement until no residue of the gas to be measured, e.g. oxygen, is present or the measuring elements no longer measure a residual concentration of this gas or until a constant, extremely low value of the gas to be measured has been established, which can be used as a zero value,

[0024] 2. that the gas, which is present under pressure in the container, enters the measuring chamber which is at ambient pressure at the beginning of the measurement, whereupon the pressure of the gas, the temperature and the concentration of the gas to be measured, e.g. the oxygen concentration, are measured in the measuring chamber,

[0025] 3. that the sealable connecting element between the measuring chamber and the expansion chamber is opened, whereupon the gas expands into the expansion chamber and then the pressure of the gas, the temperature and the concentration of the gas to be measured are measured again inside the measuring chamber and the expansion chamber connected to it via a connecting element,

[0026] 4. whereupon the headspace volume of the container and the quantity of gas to be measured, e.g. the amount of oxygen in the headspace, are calculated from the determined pressure differences in a computing and evaluation unit.

[0027] From the determined quantity of the gas to be measured, e.g., oxygen, the so-called foreign gas volume is calculated, assuming that this can only come from the ingress of air during the filling process. This is the gas volume enclosed in the container during the filling process. The method according to the invention is preferably carried out in such a way that the headspace volume is calculated using Boyle's law from the values ​​for the volume of the measuring chamber, the expansion chamber, and the pressure and temperature measured in the measuring chamber and the expansion chamber. p1*VOL1 = p2*VOL2 where:

[0028] VOL1 is the volume of the hollow needle and the measuring chamber including the connecting lines and

[0029] VOL2 is the volume of the hollow needle, the measuring chamber and the expansion chamber including the connecting lines and valves.

[0030] In the same way, the method according to the invention makes it possible to calculate a total absolute quantity of the at least one measured gas from the measured gas partial pressures at the respective prevailing pressure. For example, if the absolute amount of oxygen has been calculated, the amount of foreign gas in the headspace volume can be determined in the same way using the method according to the calculation rules used in the laboratory instructions of various beer manufacturers, e.g., HEINEKAN MATERIAL & EQUIPMENT STANDARDS AND CODE Brewery Processes and Control Conditions - Laboratory instructions, pages 1-5, for calculating the gas content in the headspace of containers containing beer.

[0031] SalaryFG=VOL FG*((exp Λ (-A+(B / t)A / hs)A / hs)+(1000, / VOL Fl)

[0032] In this mean:

[0033] Content FG: the total content of foreign gas in the entire container;

[0034] VOL FG: the total volume of foreign gas in the container,

[0035] VOLFI: the volume of liquid in the container,

[0036] VOLKopf : the volume of the headspace

[0037] VOL KopfO2; the volume O2 in the head space or Head Space /

[0038] To simplify the measurement procedure, the measurement can be carried out at a standardized temperature of 20 °C, which simplifies Heineken's formula to account for the temperature dependence as follows:

[0039] Salary FG=VOL FG*((14.82A / OLKopf) + (1000 / VOL Fl))

[0040] When applying this formula to e.g. the headspace volume of a container and measuring e.g. the oxygen content at 20 °C

[0041] VOL FG = VOLkopf02*4*((14.82 / VOLkopf)+ (1000 / VOL Fl)

[0042] The multiplier of 4 introduced here is necessary because it is known that the air contains 4 times as much nitrogen and noble gases as oxygen and therefore the total headspace volume must also be 4 times as large as the measured oxygen volume.

[0043] Finally, it is possible to deduce the filling quantity of the container from the calculated headspace volume, since the filling quantity corresponds to the total volume of the container minus the headspace volume.

[0044] In this way, using a simple device and a very simple method, it is possible to determine all values ​​that are essential for economic, quality, and health considerations. The oxygen content in the headspace volume of a container is essential for quality and health considerations; from an economic perspective, the total fill level of the container is essential, as this must comply with legal requirements. Among other things, the method according to the invention makes it possible to calculate all of these values ​​with a single measurement.To reliably prevent measurement errors, the method according to the invention is further conducted such that, before and after each measurement, the interior of the device consisting of the measuring chamber, the connecting element, and the expansion chamber is purged with an inert gas, preferably nitrogen, for a predetermined period of time, preferably between 10 and 60 seconds, in particular at least 20 seconds, and even more preferably at least 30 seconds. During a purging process, the gas-tight sealable connecting elements are opened and / or closed at staggered times. This ensures that any residual oxygen or other gases to be measured contained in the piping system are completely expelled before a subsequent measurement.

[0045] The device according to the invention and the method according to the invention are explained in more detail below with reference to the example shown in the figure.

[0046] Fig. 1 is a diagram of a structure of the device according to the invention,

[0047] In the figure, 1 denotes a container, which container 1 is filled with a liquid pressurized by CO2 or a protective gas. In addition to the liquid, the container 1 has a headspace 2. In order to measure the gas content, in particular the oxygen content in the headspace 2, the perforation device, in particular a hollow needle 3, is inserted into this headspace 2. This hollow needle 3 penetrates the container 1 in such a way that there is no risk of gas escaping around the perforation point. The gas pressure existing in the headspace of the container will flow into the measuring chamber 4 until an equilibrium pressure p1 is reached in the measuring chamber 4, which has a precisely defined volume VOL1.The measuring chamber 4 not only has a precisely defined volume, but also a precisely defined volume at each temperature in order to enable a reproducible measurement not only of the gas content in the container 1, but also to subsequently calculate the headspace volume 2 of the container 1.

[0048] After equilibrium has been established between the headspace 2 of the container 1 and the measuring chamber 4, a connecting element 5, in this case a two-way valve, is opened and the gas present in the measuring chamber 4 and the headspace 2 of the container 1, which is still under increased pressure, is allowed to flow into the so-called expansion chamber 6 until pressure equalization occurs. The expansion chamber 6, like the measuring chamber 4, has a precisely defined volume. After equilibrium has been established, the pressure p2 in the system, consisting of the volume of the headspace 2, the measuring chamber 4, and the expansion chamber 6, is again measured. From the measured pressure values ​​as well as the known volume of both the measuring chamber 4 and the expansion chamber 6, it is then possible to calculate the headspace volume 2 of the container 1 using Boyle-Mariotte's law.In the same way, the oxygen partial pressure can be calculated from the measured values ​​obtained and from the fact that the pressure inside the container 1 can also be calculated from the determined variables. From this, it can be calculated whether, in addition to CO2, foreign gases have been introduced or entered into the container 1. After the measurement has been completed, the perforation device, i.e., the hollow needle 3, is withdrawn from the container 1, a further valve 7 attached to the expansion chamber 6, in particular a multi-way valve 7, is opened, and the device for measuring a headspace volume or an oxygen content in the headspace 2 of a container 1 is purged with an inert gas. The device is thus available for another measurement. The interior should be cleaned after at most 10 measurements.For this purpose, in a first step, the device is rinsed with a cleaning agent, whereby a cleaning agent is introduced into the multi-way valve 7 via a flushing device 8 and pumped through the measuring device. In a second step, it is rinsed with deionized or distilled water. This cleaning process is carried out manually or semi-automatically, depending on the configuration. In a third step, for drying purposes and in particular to free the device from any residual quantities and any subsequent measurement, possibly interfering gas concentrations of oxygen or CO2 or other possibly interfering gases, the device is further switched so that a purge gas, in this case nitrogen, is introduced into the device via the multi-way valve 7 via a purge gas line 9 and is allowed to flow through it for several minutes. To ensure that, for example,Oxygen is introduced into the interior of the measuring device, the procedure is such that the valves are successively closed so that an excess pressure of the gas present in the system (in this operating state this is the purge gas) is prevented inside the device and an equilibrium is always achieved in which a constant pressure of the inert gas, in this case nitrogen, essentially corresponding to atmospheric pressure, is maintained inside the device. For a new measurement, before starting the measurement, it is again purged with inert gas and the pressure prevailing in the individual chambers 4, 6 is determined, the temperature is determined and, in particular, it is checked whether there is still no residual oxygen inside the measuring device. If no, the next measurement can be carried out.

[0049] Of course, the purging device can also be designed differently. For example, two separate purging lines for two different cleaning fluids can be provided, along with a purging gas line to blow dry the interior of the system. Instead of using a suction device to empty the interior of the measuring device, i.e., the measuring chamber and expansion chamber, it is also possible to conduct gas or liquid through it until no residue from the previous measurement can be contained. In this case, the pressure reduction inside can be omitted.

Claims

Patent claims 1. A device for measuring a headspace volume (VOLhead) of a container above a liquid, wherein an overpressure of either a gas contained in the liquid, such as CO2, or a protective gas, such as N2, is present in the headspace volume, as well as for measuring the content of one or more gases to be measured contained in the headspace, comprising a measuring chamber that can be placed gas-tight onto the container having a defined volume (VOLtotal), which measuring chamber contains a perforation device, preferably a hollow needle, and a measuring device for determining at least one gas to be measured contained in the headspace of the container, preferably oxygen, characterized in that the measuring chamber is coupled to an expansion chamber having a first gas-tight sealable connecting element, that the expansion chamber is coupled to at least one rinsing and cleaning device via gas-tight sealable connecting elements,that the measuring chamber, the connecting element, and the expansion chamber have precisely defined, constant volumes (VOL1, VOL2) at a predetermined temperature (T), and that at least one sensor element and an evaluation and computing unit are provided for determining the headspace volume (VOLkopf) and the content of at least one gas to be measured contained in the headspace.

2. Device according to claim 1, characterized in that measuring devices for measuring the concentration of at least one gas to be measured (concentrated gas), the pressure (p1), and the temperature (T1) are provided in the measuring chamber.

3. Device according to claim 1 or 2, characterized in that the first gas-tight sealable connecting element is designed as a two-way valve.

4. Device according to claim 1, 2 or 3, characterized in that the measuring chamber, the expansion chamber and the perforation device are further connected via a multi-way valve to both at least one purging device and to a source of purging gases via a pressure reduction device.

5. Device according to claim 4, characterized in that two flushing devices are provided, one for the inert gas, which is coupled to the pressure reduction device, and one for the cleaning liquids.

6. Device according to one of claims 1 to 5, characterized in that the perforation device is encased by a deformable sealing element.

7. A method for measuring a headspace volume of a container of a liquid, wherein in the headspace volume (VOLkopf) there is an overpressure of either a gas contained in the liquid, such as CO2, or a protective gas, such as N2, and for measuring the content of one or more gases to be measured contained in the headspace with a device for measuring a headspace volume (VOLkopf) of a container according to one of claims 1 to 6, in which in a first step a measuring chamber having a volume is placed gas-tight onto a closure or a perforable wall of the container and then the closure or the perforable wall of the container is penetrated with a perforation device, preferably a hollow needle, characterized in that the gas to be measured, which is present under pressure in the container, is transferred into the measuring chamber, whereupon the pressure of the gas (p1) in the measuring chamberthe temperature (T1) of the gas inside the measuring chamber and the concentration of at least one gas to be measured (conc. gas 1), preferably an oxygen concentration, the closable connecting element between the measuring chamber and an expansion chamber is opened, the gas to be measured is allowed to expand into the expansion chamber, and the pressure of the gas to be measured (p2), the temperature (T2), and the O2 concentration inside the measuring chamber and the expansion chamber (conc. gas 2) connected thereto via a connecting element are measured again, whereupon the headspace volume (VOLkopf) of the container, the pressure in the container (p), and the partial pressure of the at least one measured gas (pGas) are calculated in relation to a predetermined zero value in a computing and evaluation unit.

8. The method according to claim 7, characterized in that before each measurement, an interior of the device for measuring the headspace volume (VOLhead) is purged with an inert gas, and that after purging of the interior, any content of the at least one gas to be measured present in the interior is used for a zero value correction.

9. The method according to claim 7 or 8, characterized in that the headspace volume (VOLhead) is calculated using Boyle's law from the values ​​for the volume of the measuring chamber, the expansion chamber (VOL1, VOL2), and the pressure (p1 and p2) measured in the measuring chamber and the expansion chamber.

10. Method according to claim 7, characterized in that a total absolute quantity of the gas to be measured (gas abs ; from the measured gas partial pressures (p Gas1 ,p Gas2) is calculated at the prevailing pressure (p1 or p2).

11. Method according to one of claims 7 to 10, characterized in that it is used to measure an oxygen content (conc. O2) in the headspace of a container.

12. Method according to one of claims 7 to 11, characterized in that a foreign gas quantity, in particular air enclosed in the headspace volume, is calculated from the calculated absolute oxygen quantity.

13. Method according to claim 12, characterized in that from the calculated headspace volume a filling quantity of the container is calculated according to the formula: VOLtotal- VOLhead = filling quantity is calculated.

14. Method according to one of claims 7 to 13, characterized in that before and after each measurement, the interior of the device consisting of the measuring chamber, the connecting element and the expansion chamber is purged with an inert gas, preferably nitrogen, for a predetermined period of time, preferably between 10 and 60 seconds, in particular at least 20 seconds, more preferably at least 30 seconds, and that during a purging process, the gas-tight sealable connecting elements are opened and / or closed at different times.

15. Method according to one of claims 7 to 14, characterized in that before each Measurement after the inert gas purging of the interior, a check and, if necessary, adjustment of the zero value is carried out.

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