Mobile gas measurement system for the quantitative determination of gases

Abstract

The invention relates to a gas measurement system for the quantitative detection of gases, comprising at least the following components: a measuring chamber (1) with a cavity jacket, a piston (2) movable therein with a stopper (5), at least one inlet opening (4), and at least one gas sensor (3) gas-tightly connected to the outer wall of the measuring chamber (1), which makes contact with the cavity of the measuring chamber (1) via at least one opening on at least one contact surface (7). The gas sensor can be replaceable or permanently installed. Syringes, in particular large-bore medical syringes, can be used to manufacture the gas measurement system. Since the dead space in the gas measurement system is reduced to a minimum by the design according to the invention, external pumps can be dispensed with when measuring gas concentrations.For use as a mobile device, the gas measuring system can additionally include the following components: device for data acquisition (15), rotary potentiometer (14), main switch (18), temperature and pressure sensor (16), power supply (17), display (19), conductivity sensor (20), memory card (21). The gas measuring system according to the invention can be used both for individual measurements of gas samples and for process gas measurements.

Description

[0001] The present invention relates to a gas measurement system for the quantitative detection of gases, which enables the quantitative determination of gas concentrations in a gas mixture in real time. The gas measurement system comprises a measuring chamber with a hollow shell, a piston movable therein, at least one inlet opening through which sampling takes place, and at least one gas sensor connected to the outer wall of the measuring chamber. The gas sensor can be replaceable or permanently installed.

[0002] Measurement systems for the quantitative detection of gases are well-known in the art. They require the gases to be detected to flow around the gas sensors. This is usually achieved by drawing the gaseous medium through an inlet opening of the measurement chamber.

[0003] Conventional gas detection systems are often bulky, stationary devices with built-in gas sensors that can only detect specific gases. A gas sample is usually taken using a connected pump system. A pump fills the dead space in the measurement chambers and connecting hoses, where residual air remains, with the gas sample, while simultaneously pumping out the residual air. The use of pumps contributes to higher manufacturing and operating costs for conventional gas detection systems and significantly limits their use as portable devices.

[0004] The invention is therefore based on the object of providing a compact, mobile and cost-effective gas measuring system with which a quantitative determination of different gases in real time is possible, even with small gas samples of less than 150 ml.

[0005] To solve this problem, the approach is to reduce the dead space in the system to a minimum. For this purpose, a device is provided which comprises at least the following components: a measuring chamber (1) with a casing having a hollow space, a piston (2) movable therein with a plug (5), an inlet opening (4), at least one gas sensor (3) which is connected in a gas-tight manner to the outer wall of the measuring chamber (1) and which is connected to the interior of the measuring chamber (1) via an opening on a contact surface (7) ( Fig. 1).

[0006] The measuring chamber (1) and the piston (2) are preferably made of plastic and are designed such that together they form a syringe. The cavity of the measuring chamber (1) is preferably cylindrical. Other shapes, such as oval, rectangular, or polygonal, are also conceivable.

[0007] The plug (5) forms a gas-tight seal against the inner wall of the measuring chamber (1). It is preferably made of an elastic material such as elastomer, rubber, or silicone and can have either a smooth surface or at least two sealing rings (24).

[0008] The inlet opening (4) is preferably designed in the form of a conical or cylindrical nozzle. This can additionally have a screw or plug-in thread at the end.

[0009] Depending on the specific application, the gas measurement system according to the invention comprises one or more gas sensors (3). These can be arranged, for example, radially relative to the central axis of the measurement chamber (1) or in another arrangement in the outer wall of the measurement chamber (1). The gas sensors (3) can be permanently installed on the outer wall of the measurement chamber (1) or can be removable and replaceable.

[0010] To attach the gas sensors (3) to the outer wall of the measuring chamber (1), the gas measuring system can have one or more gas sensor receptacles (6) on the contact surfaces (7). These are preferably designed to accommodate the gas sensors in a gas-tight manner.

[0011] For accommodating commercially available cylindrical gas sensors, the design of the gas sensor receptacles (6) with a round opening with a diameter corresponding to the diameter of the gas sensor used is particularly advantageous. Other shapes of gas sensor receptacles are also possible. The material used can be, for example but not exclusively, an elastic material such as elastomer, rubber, or silicone.

[0012] The gas sensors (3) are in contact with the interior of the measuring chamber (1) through openings in the measuring chamber (1) at the contact surface (7). The dimensions and shape of the openings at the contact surface (7) are such that, on the one hand, no air can enter the space between the stopper (5) and the inlet opening (4) at the head of the piston (2) during the measurement. On the other hand, the contact surface (7) should be as large as possible to ensure that a concentration equilibrium is established as quickly as possible during a measurement.

[0013] If a plug with a smooth surface without sealing rings is used, the opening on the contact surface (7) must not be wider than the width of the sealing surface of the plug (5).

[0014] .In the case of a plug with two or more sealing rings (24), the width of the opening (distance AB in Fig.6) at the contact surface (7) must not be greater than the distance (CD) between two adjacent sealing rings (24) of the plug (5) at the head of the piston (2). This ensures that when the plug (5) passes over the contact surface (7) during sampling, no air or gas exchange takes place between the two spaces of the measuring chamber (1) separated by the plug. This design prevents air from being briefly sucked in instead of the gas sample, which would falsify the measurement results. This is particularly important for pistons whose plugs have only two sealing rings.

[0015] The length of the opening on the contact surface (7) preferably corresponds to the diameter of the opening of the sensor holder (6), but can also have a different value.

[0016] An optimal shape and size of the opening on the contact surface (7) is approximately an elongated hole with a width between the long sides corresponding to the distance between two adjacent sealing rings (24) of the plug (5), and the length between the two final, opposite curves, which approximately corresponds to the inner diameter of the sensor holder (6) (Figure 7).

[0017] Although the optimal shape and size of the opening at the contact surface (7) described above is particularly preferred, other configurations such as a rectangle, circle, oval or the like are also conceivable, provided that no undesired contact of the gas sample with the air can occur during sampling through the opening.

[0018] According to the invention, the gas sensor (3) can be fixed in the gas sensor receptacle (6) in a gas-tight manner in different ways. Thus, the gas sensor (3) can be fixed in the gas sensor receptacle (6.1) either by an interference fit or by bonding ( Fig. 1a). The gas sensor (3) can also be secured by inserting a rubber ring insert (6.2) ( Fig. 1b) or using an internal thread in the gas sensor holder (6.3) ( Fig. 1c). This variant requires that the gas sensor to be connected has a suitable external thread.

[0019] Further designs of the gas sensor holder are in Fig. 3, Fig. 4, Fig. 5 and Fig. 6 and are described in detail in the embodiments.

[0020] The gas measuring system according to the invention can be equipped with a Fig. 1, or can also be equipped with several gas sensors (3). Fig.Figure 2 shows an example of a gas measurement system with three gas sensor receptacles (6), which is suitable for accommodating three different gas sensors (3) for measuring three different gases. For example, a methane NDIR sensor, a carbon dioxide NDIR sensor, and a hydrogen thermal conductivity sensor can be used to determine the volume concentrations of these gases, for example, in a biogas sample. Advantageous designs are those in which the gas sensors are not permanently fixed to the measurement chamber, but are insertable and replaceable. This enables quick and cost-effective adaptation of the gas measurement system to specific requirements without having to replace the entire system.

[0021] To manufacture the gas measuring system, the measuring chamber can either be manufactured in one piece with the gas sensor receptacles and recesses for the contact surfaces, e.g. using an injection molding process, or the commercially available, in particular medical, large-capacity syringes can be used, which are prepared in a suitable manner, as described below in the exemplary embodiments.

[0022] The gas measuring system according to the invention can be used both for individual measurements of gas samples and for process gas measurements.

[0023] In Fig.Figure 8 shows an example of the gas measurement system, which is designed for individual measurements and is suitable for use as a mobile gas measurement system. In this example, the gas measurement system additionally has the following components: a device for measuring value acquisition (15) (e.g., a microcontroller) with a rotary potentiometer (14) and a main switch (18), a temperature and pressure sensor (16), a power supply (17) (e.g., a rechargeable battery), a display (19) (e.g., a 2.8-inch touch display), a conductivity sensor (20), and a memory card (21) (e.g., a micro SD card).

[0024] Fig. Figure 9 shows the general operating principle of the gas measurement system designed for single measurements.

[0025] The piston of the gas measurement system (22) is fully depressed before a measurement, so the measurement chamber contains no air, except for a small residual volume in the inlet opening at the head end. To perform the measurement, the inlet opening of the gas measurement system (22) is connected gas-tight to the sampling syringe (23), e.g., using an adapter (25). Fig. 9a).

[0026] The gas sample is then introduced into the measuring chamber of the gas measuring system (22) by pulling the piston of the gas measuring system while simultaneously pressing the piston of the sampling syringe (23) ( Fig. 9b).

[0027] Pulling the piston of the gas measurement system creates a space in the measuring chamber, which immediately fills with the connected gas sample due to the generated negative pressure. The dead space of the system is thus limited to the small residual volume in the gas sensors themselves, at the contact surface (7) between the gas sensors (3) and the outside of the measuring chamber (1), and in the inlet opening (4).

[0028] In order to minimize the measurement errors caused by the dead space when calculating the gas concentrations in the sample, the gas measurement system must be calibrated to a specific sample volume before the actual measurement, which corresponds to the volume of the gas samples to be measured subsequently.

[0029] The gas measuring system according to the invention enables the detection of gases even in smaller sample volumes, as long as it is ensured that the piston (2) has moved completely over the opening on the contact surface (7) between the measuring chamber (1) and the gas sensors (3) and the current size of the sample volume is transmitted to the device for measuring value acquisition. The minimum sample volume depends on how close the openings are to the contact surfaces (7) and thus the gas sensors (3) are to the inlet opening (4). The composition of the air in the residual volume varies only slightly from measurement to measurement, so that the measurement result is not significantly influenced and the deviations are in the single-digit volume percentage range of less than 5%. This requires, however, that the measuring chamber and thus the dead space is flooded with ambient air again after each individual measurement.

[0030] The gas measurement system described above, which does not require the use of a conventional electric pump, allows a single measurement within a few minutes, which is less complex than a measurement using a conventional gas chromatograph, for example.

[0031] Alternatively, the gas measuring system according to the invention can also be adapted so that it can be used for process gas measurement ( Fig. 10). For this purpose, an external pump (27) is connected to a sample inlet (26), e.g., via a screw or plug-in thread or a connecting hose (28), to the gas measurement system (22). Either an additional opening or recess in the measurement chamber or one of the existing gas sensor receptacles can be used as the sample outlet (30). In the latter case, a connection adapter (29) can also be used to divert the sample gas.

[0032] To perform process gas measurements, the piston remains open at a constant position, and the gas sample is continuously pumped through the measuring chamber. If single-gas measurements are to be performed with the gas measurement system, the sample outlet (30), as well as the unused gas sensor receptacles, can be sealed gas-tight with a plug in the shape of a gas sensor.

[0033] Due to its flexibility and compact size, the gas measurement system according to the invention enables versatile applications in various fields of application, such as in the chemical, petrochemical or processing industries, in medicine, in biogas plants, for learning and demonstration purposes in educational institutions, in security and monitoring systems, etc.

[0034] Further advantages, features, and possible applications of the invention are described below using exemplary embodiments with reference to the drawings. In the drawings, the piston (2) is not shown in the final measuring position in all longitudinal sectional views of the measuring chamber (1), but rather in the position where the plug (5) passes over the openings on the contact surfaces (7). At the beginning of the measurement, however, the piston (2) is fully depressed, and the plug (5) is located on the far right at the inlet opening (4) of the measuring chamber (1).

[0035] The drawings show: Fig. 1: The simplest design with only one gas sensor, intended to illustrate the principle of the gas measurement system according to the invention, in three different views. View BB shows a cross-section of the measuring piston (1) with a gas sensor (3) mounted in the gas sensor holder (6). Fig. 1a, Fig. 1b and Fig.1c show in view AA different mounting options for the gas sensor in the gas sensor holder in an enlarged section of the longitudinal section. Fig. 1a, the gas sensor (3) is fixed in the gas sensor holder (6.1) either by an interference fit or by bonding. In the Fig. 1b, the gas sensor (3) is secured in the gas sensor holder (6.2) by inserting a sealing ring, and in the Fig. 1c is fixed by an internal thread in the gas sensor holder (6.3). Fig. 2: An example of a gas measurement system with three gas sensor receptacles (6), suitable for accommodating and measuring three different gas sensors (3), in three views. View BB shows a cross-section of the measuring piston (1) with three gas sensors (3), each mounted in three gas sensor receptacles (6). Fig.3: An example of the gas sensor holder (6.4), which is designed as an elastic sleeve with recesses for the gas sensors (3) and is pulled over the measuring chamber (1). View DD shows a cross-section of the gas measuring system in the area of ​​the gas sensors (3). View CC shows an enlarged section of the longitudinal section. Fig. 4: An example of the gas sensor mount, depicting a silicone sleeve (9) open on one side, which is pressed against the outside of the measuring chamber (1) by means of one or more screws through an elastic compression sleeve (10) and two hose clamps (11). View BB shows a cross-section of the gas measurement system in the area of ​​the gas sensors (3). View AA shows an enlarged section of the longitudinal section. Fig.5: An example of the gas sensor mount, where the silicone sleeve (9) is pressed against the outside of the measuring chamber (1) by the compression sleeve (10) using screws (12) and nuts (13). View BB shows a cross-section of the gas measurement system in the area of ​​the gas sensors (3). View AA shows an enlarged section of the longitudinal section. Fig. 6: An example of a piston (2) with a plug (5) with three sealing rings (24). AB is the width of the opening in the outer wall of the measuring chamber (1) at the contact surface (7), CD is the distance between two adjacent sealing rings (24) of the plug (5) at the head of the piston (2). View C shows an enlarged section of the longitudinal section in the area of ​​the gas sensor (3). Fig.7: an example of the optimal shape and size of the opening on the contact surface (7) when the piston (2) is used with a plug (5) with at least two sealing rings (24), as in the example of Fig. 6. 7a: side view, 7b: top view, 7c: cross section. Fig. Figure 8: An example of the gas measurement system for single measurements for use as a mobile gas measurement system with the following additional components: device for measuring values ​​(15), rotary potentiometer (14), main switch (18), temperature and pressure sensor (16), power supply (17), display (19), conductivity sensor (20), memory card (21). 8a: three-dimensional representation, 8b: front view, 8c: rear view. Fig.Figure 9: The general operating principle of the gas measurement system, which is designed for single measurements. Figure 9a: The inlet of the gas measurement system (22) is connected gas-tight to the sampling syringe (23) using an adapter (25), and the piston (2) of the gas measurement system is pushed through. Figure 9b: By pulling the piston (2) of the gas measurement system (22) and simultaneously pushing the piston of the sampling syringe (23), the gas sample is introduced into the measuring chamber (1) of the gas measurement system (22). Fig. 10: An example of the use of the gas measurement system according to the invention for a process gas measurement. For this purpose, an external pump (27), which draws in the gas sample via the sample inlet (26), is connected to the gas measurement system (22) via a connecting hose (28). A connection adapter (29) contains a sample outlet (30) for discharging the sample gas from the gas measurement system (22). Examples of implementation: Production of the gas measurement system based on commercially available syringes

[0036] When using commercially available syringes in the manufacture of the gas measuring system, openings or recesses for the contact surface are created in the jacket of the syringe, e.g. by punching, drilling, cutting out or similar.

[0037] In order to ensure that the gas sensors can be attached to the contact surfaces in a stable and gas-tight manner, specially designed gas sensor holders with additional fastening devices are usually required.

[0038] Thus, the gas sensor holder (6.4) in Fig.3 is an elastic sleeve, e.g. made of elastomer, silicone, rubber or similar, which has recesses for the gas sensors. The sleeve is fixed to the outside of the measuring chamber using an interference fit. The gas sensors are also held in place by an interference fit in the recesses of the rubber sleeve (6.4) on the outside of the measuring chamber (1). To ensure that this construction remains gas-tight even when the measuring chamber is subjected to a slight overpressure or underpressure (+ / - 60 hPa), the sleeve (6.4) must be pressed against the outside of the measuring chamber (1) with a relatively high force, depending on the material properties. This requires either a high modulus of elasticity of the material used, or an interference fit with greatly differing inner and outer diameters, which is often difficult to implement in practice.

[0039] A solution is offered by a modified form of this construction, as in Fig.4. Here, a silicone sleeve (9), open on one side, is pressed against the outside of the measuring chamber (1) by means of an elastic compression sleeve (10) and two hose clamps (11) using one or more screws. By opening the hose clamps (11), the gas sensors (3), which sit tightly in the silicone sleeve (9) thanks to an interference fit, can be easily replaced. The compression sleeve (10) ensures even pressure on the silicone sleeve (9), even under higher overpressure or underpressure.

[0040] Instead of hose clamps, the press sleeve (10) can be held together with screws (12) each with a nut (13) ( Fig. 5) so that the necessary contact pressure can be exerted on the silicone sleeve (9).

[0041] In practice, the statements made in the Fig. 4 and Fig.5. These designs ensure that the gas sensors can be replaced within a very short time without complex manipulation of the measuring chamber. Furthermore, gas sensor receptacles that are not currently needed for gas measurement due to a specific problem can simply be temporarily sealed gas-tight with a suitable plug, e.g., a cylindrical plug. Individual measurements with the gas measuring system according to the invention

[0042] To perform a measurement, first, a 150 ml gas sample is taken from the container containing the gas to be analyzed using the sampling syringe. This is done using a 2.5 cm long adapter (25) in the form of a piece of silicone tubing. Gas exchange with the environment must be prevented during sample transfer, in this case by compressing the silicone adapter tubing. This adapter, along with the syringe, is then connected to the inlet port (4) of the gas measurement system (22). Fig.9a). The piston (2) of the gas measurement system (22) is completely retracted. If a thermal conductivity sensor (20), as in this case, is part of the system, the measuring bridge must now be calibrated to the ambient air before the measurement using a rotary potentiometer (14) manually, or with the aid of a digital potentiometer controlled by software. The sample is then introduced into the measuring chamber (1) of the gas measurement system (22) by pulling the piston (2) of the gas measurement system and simultaneously pressing the piston of the sampling syringe (23). Fig. 9b).

[0043] The sample collection is confirmed to the system via an input function on the touch display (19). In this version, it takes approximately three minutes for the gas sensors (3) to obtain a stable result. Correction calculations are performed independently by the system, taking into account the cross-sensitivities of the gas sensors (3) as well as temperature and pressure influences. The measured concentration increase during a measurement series, as well as the final measurement result itself, can be saved separately on a micro SD card (21) along with the current time.

[0044] By utilizing the capabilities of a touch display (19), a user interface was created for this prototype, which not only allows guided measurements to be carried out, but also implements other functions. These include calibrating the sensors (3) to the gas to be tested, directly outputting results from previous measurement series, and the option to exchange gas sensors. For example, an additional gas sensor can be connected externally, one designed for low CO2 concentrations down to 5000 ppm. This enables functions such as using the system as a CO2 traffic light or conducting absorption experiments in a school context. Once a measurement is complete, the syringe for sampling is withdrawn and the gas sample is expelled through the inlet opening (4) when the piston of the gas measuring system is manually retracted.The piston (2) is then completely withdrawn from the cylinder, and the measuring chamber (1) is exposed to ambient air for at least one minute. This ensures that the remaining volume is completely filled with air. Only then is the piston (2) reinserted and another measurement can be performed.

[0045] The series of measurements shown in the table were conducted using one of the first prototypes based on this measuring principle. In each case, a 150 ml gas sample was mixed with a second syringe containing pure gases. This was done manually, which is why errors may have occurred, estimated at one percent. The accuracy achieved below requires that the carbon dioxide sensor and the methane sensor are regularly calibrated to 100 vol% and 50 vol%, respectively. The results are summarized in the table below. Gases Proportions of the mixture in volume percent Measured proportions in volume percent Absolute deviation from the target value in % Measurement 1 CO2 50 50,26 0,26 CH4 0 0,01 0,01 H2 0 0,25 0,25 N2 50 48,11 -1,89 H2O 0 1,37 1,37 Measurement 2 CO2 0 0,38 0,38 CH4 50 50,73 0,73 H2 0 -0,47 -0,47 N2 50 48,15 -1,85 H2O 1,22 1,22 Measurement 3 CO2 0 0,02 0,02 CH4 0 0,2 0,20 H2 50 50,17 0,17 N2 50 48,5 -1,50 H20 0 1,11 1,11 Measurement 4 CO2 50 49,18 -0,82 CH4 0 0,26 0,26 H2 50 48,8 -1,20 N2 0 0,97 0,97 H2O 0 0,79 0,79 Measurement 5 CO2 0 0,34 0,34 CH4 50 51,07 1,07 H2 50 51,44 1,44 N2 0 -3,8 -3,80 H2O 0 0,95 0,95 Measurement 6 CO2 33,3 33,86 0,56 CH4 33,3 32,52 -0,78 H2 33,3 31,9 -1,40 N2 0 0,76 0,76 H2O 0 0,96 0,96 Measurement 7 CO2 33,3 32,01 1,54 CH4 33,3 34,84 -1,29 H2 33,3 32,65 -0,65 N2 0 -0,31 -0,31 H2O 0 0,81 0,81 Measurement 8 CO2 0 0,21 0,21 CH4 30 29,14 -0,86 H2 70 71,01 1,01 N2 0 -1,24 -1,24 H2O 0 0,89 0,89 Measurement 9 CO2 10 9,56 -0,44 CH4 20 20,1 0,10 H2 70 71,19 1,19 N2 0 -1,68 -1,68 H2O 0 0,84 0,84 Measurement 10 CO2 20 21,6 1,60 CH4 10 11,47 1,47 H2 60 60,61 0,61 N2 10 5,5 -4,50 H20 0 0,82 -0,82 Measurement 11 CO2 20 23,92 3,92 CH4 0 0,02 0,02 H2 80 80,7 0,70 N2 0 -5,43 -5,43 H2O 0 0,78 -0,78 Measurement 12 CO2 20 18,71 -1,29 CH4 60 63,55 3,55 H2 10 8,74 -1,26 N2 10 7,56 -2,44 H2O 0 1,44 1,44 Measurement 13 CO2 0 0,78 0,78 CH4 40 40,31 0,31 H2 40 38,44 -1,56 N2 20 19,61 . -0,39 H2O 0 0,86 0,86 Measurement 14 CO2 60 60,22 0,22 CH4 10 11,1 1,10 H2 20 19,1 -0,90 N2 10 8,87 -1,13 H2O 0 0,71 0,71 Measurement 15 CO2 10 10,32 0,32 CH4 10 8,72 -1,28 H2 10 11,65 1,65 N2 70 68,58 -1,42 H2O 0 0,73 0,73 Measurement 16 CO2 33,3 32,54 -0,76 CH4 33,3 34,04 0,74 H2 33,3 31,51 -1,79 N2 0 1,33 1,33 H2O 0 0,58 0,58 Measurement 17 CO2 50 48,91 -1,09 CH4 50 51,66 1,66 H2 0 -0,93 -0,93 N2 0 -0,16 -0,16 H2O 0 0,52 0,52 Measurement 18 CO2 33,33 33,13 -0,20 CH4 33,33 33,43 0,10 H2 33,33 32,66 -0,67 N2 0 0,28 0,28 H2O 0 0,51 0,51 Measurement 19 CO2 20 19,39 -0,61 CH4 20 18,68 -1,32 H2 20 20,36 0,36 N2 40 40,78 0,78 H2O 0 0,8 0,80 Measurement 20 CO2 20 18,15 -1,85 CH4 10 10,68 0,68 H2 60 59,9 -0,10 N2 10 10,47 0,47 H2O 0 0,79 0,79 Measurement 21 CO2 10 12,18 2,18 CH4 30 26,79 -3,21 H2 50 51,42 1,42 N2 10 8,81 -1,19 H2O 0 0,79 0,79 Measurement 22 CO2 50 49,22 -0,78 CH4 30 30,6 0,60 H2 10 11,63 1,63 N2 10 7,45 -2,55 H2O 0 0,78 0,78 Measurement 23 CO2 10 13,28 3,28 CH4 30 28,44 -1,56 H2 50 49,22 -0,78 N2 10 8,28 -1,72 H2O 0 0,79 0,79 Process gas measurements with the gas measuring system according to the invention

[0046] In this example, the gas measurement system with four gas sensor receptacles is used for gas sensors, with one access point being used to connect a small external diaphragm pump. This allows the system to perform not only individual measurements, but also process gas measurements. The piston remains open at the 150 ml position, and the gas sample is continuously pumped through the measuring chamber. Since the residual volume of air is also removed from the system in this case, higher measured values ​​are to be expected than with individual measurements; however, these can be compensated electronically by the system. The measurements for this setup show an increase of 2 vol.% of the measurement result for a 50 vol.% CO2 measurement compared to a single measurement.

[0047] If single gas measurements are to be carried out with this gas measuring system, the connection used for the pump can be closed with a plug in the shape and size of the gas sensor. List of reference symbols 1 measuring chamber 2 pistons 3 Gas sensor 4 Inlet opening 5 plugs 6 Gas sensor holder 7 Contact surface 8 rubber ring insert 9 Silicone sleeve 10 press sleeve 11 hose clamp 12 screw 13 Mother 14 rotary potentiometers 15 Device for measuring values ​​(microcontroller) 16 Temperature and pressure sensor 17 Power supply (battery) 18 main switch 19 Display 20 thermal conductivity sensor 21 Memory card 22 Gas measuring system 23 Sample syringe 24 Sealing ring 25 adapters 26 Sample inlet 27 Pump 28 connecting hose 29 Connection adapter for the gas outlet 30 Sample outlet

Claims

[1] Gas measuring system for the quantitative detection of gases, which has at least the following components: a measuring chamber (1) with a jacket with a hollow space, a piston (2) movable therein with a plug (5), at least one inlet opening (4), at least one gas sensor (3) which is connected in a gas-tight manner to the outer wall of the measuring chamber (1) and which has contact with the hollow space of the measuring chamber (1) via at least one opening on at least one contact surface (7). [2] Gas measuring system according to claim 1, wherein the cavity of the measuring chamber (1) has a cylindrical shape. [3] Gas measuring system according to one of the preceding claims, wherein the measuring chamber (1) and the piston (2) are parts of a syringe. [4] Gas measuring system according to one of the preceding claims, wherein the at least one gas sensor (3) is fixedly fixed to the measuring chamber (1) or is removable and replaceable. [5] Gas measuring system according to one of the preceding claims, wherein at least one gas sensor receptacle (6) for attaching the at least one gas sensor (3) to the at least one contact surface (7) is provided on the outer wall of the measuring chamber (1). [6] Gas measuring system according to the preceding claim, wherein the at least one gas sensor receptacle (6) has an opening which is designed to be suitable for receiving commercially available gas sensors. [7] Gas measuring system according to one of the preceding claims, wherein the plug (5) has a smooth surface or at least two sealing rings (24). [8] Gas measuring system according to the preceding claim, wherein the width of the opening at the contact surface (7) is not greater than the distance between two adjacent sealing rings of the plug (5) at the head of the piston. [9] Gas measuring system according to one of the preceding claims, wherein the length of the opening on the contact surface (7) corresponds approximately to the diameter of the opening of the gas sensor receptacle (6). [10] Gas measuring system according to one of the preceding claims, wherein the inlet opening (4) is designed in the form of a conical or cylindrical nozzle. [11] Gas measuring system according to one of the preceding claims, wherein it additionally comprises at least one of the following components: device for measuring measured values, temperature and / or pressure sensor, power supply, display, conductivity sensor, memory card. [12] Use of the gas measuring system according to one of the preceding claims for individual measurements of gas samples and / or for process gas measurements.

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