CONTINUOUS AND SEPARATE GAS ANALYSIS

Description

[0001] The invention relates to a portable gas analysis device for passing a gas flow, in particular for highly volatile compounds.

[0002] Volatile organic substances are often harmful to health. For this reason, legal maximum concentration levels must be observed in the environment and around industrial facilities. The concentration of these volatile compounds can be measured using mobile measuring devices.

[0003] The measurement to record the individual concentrations of the volatile compounds in a sample gas mixture is relatively time-consuming, taking at least several minutes. A spatially resolved measurement of the individual concentrations in large areas or large buildings is therefore very time-consuming. For this reason, a quick integration measurement (approx. 2 seconds) is first carried out to determine the locations where volatile compounds are present in higher concentrations. It is internally known that in mobile measuring devices, a gas stream from the sample gas mixture is directed to a detector, which records the total concentration of the volatile compounds in the sample gas. If volatile compounds are found, the gas stream of the sample gas mixture is directed via valves to another detector, which measures the individual concentrations of the volatile compounds in the sample gas.Such measuring devices are known, for example, from the documents US 2011 / 0259081 A1, US 2005 / 0284209 A1 or US 6,165,251 A.

[0004] These known measuring devices have the disadvantage that the search for other locations where higher concentrations of the volatile compounds could be present must be interrupted for the duration of the measurement of the individual concentrations.

[0005] Conventional measuring devices that allow simultaneous measurement have a separate measuring path for each measuring mode, with separate openings, blowers, valves, and lines for the sample gas. This multiple structure makes these measuring devices heavy and maintenance-intensive. One measuring device with an unfavorable multiple structure is known, for example, from document US 2011 / 0259081 A1.

[0006] The invention is based on the object of creating a gas analysis device that is improved in terms of compactness and speed, while also being economical in terms of consumption and wear. This object is achieved by the features of the independent claims. Advantageous further developments are the subject of the dependent claims.

[0007] In a gas analysis device for passing a gas flow, in particular for highly volatile compounds, wherein the gas analysis device comprises a search measuring path and a separation measuring path, wherein the search measuring path extends from a sample gas inlet opening to a first exhaust air opening, wherein a connecting path branches off from the search measuring path to the separation measuring path, wherein the separation measuring path extends from the connecting path to a second exhaust air opening and is connected to a carrier gas inlet opening, and wherein a separation detector is arranged on the separation measuring path, the invention provides that the gas analysis device is portable and has a control element which is designed to reverse the gas flow in the connecting path such that, in the reverse direction, a portion of a sample gas mixture entering at the sample inlet opening flows via the connecting path into the separation measuring path and the other portion follows the search measuring path.wherein a finder detector is arranged in the finder measuring path, which is designed to continuously detect the presence of a group of volatile compounds.,

[0008] First, let's explain a few terms in more detail: A detector measurement path is the path of the sample gas mixture within the gas analysis device, where the presence of volatile compounds is detected along the path. The detector measurement path is used to search for these volatile compounds.

[0009] A separation measurement path is the path of the sample gas mixture within the gas analysis device, where the components of the mixture are separated along the path to determine the individual concentrations. The separation measurement path thus serves to separate a gas mixture into its components in order to determine the concentrations of the individual compounds.

[0010] The invention is based on the idea of ​​controlling the measurement of the individual concentrations of the volatile compounds by changing the direction of the gas flow in the connecting path. As long as no measurement is being performed, carrier gas flows from the connecting path into the detector measurement path. By reversing the direction of the gas flow in the connecting path using the control element, a portion of the sample gas mixture flows from the detector measurement path via the branching connecting path into the separation measurement path, allowing the individual concentrations to be measured. The other portion of the sample gas remains in the detector measurement path, allowing the search for the presence of volatile compounds to continue thanks to this division of the sample gas and the detector detector located there. The gas flow can be generated by flow-generating elements such as blower units and / or other suitable devices such as flow directors and valves.

[0011] No valve is required between the connecting measurement path and the detector measurement path. Instead, the gas flow is reversed by a control element that regulates the pressure conditions between the separation measurement path and the detector measurement path. Thus, in a reversed flow direction, part of the sample gas mixture entering the sample inlet can flow via the connecting path into the separation measurement path, while the other part follows the detector measurement path. The direction of the gas flow can be controlled by changing the pressure difference between the detector measurement path and the separation measurement path.

[0012] When determining whether any volatile compounds are present at the measurement locations, the control element causes the pressure in the separation measurement path to be higher than in the detector measurement path. This causes carrier gas to flow from the carrier gas inlet through the connection path into the detector measurement path. The sample gas flowing through the sample gas inlet is thereby prevented from entering the separation measurement path. In the detector measurement path, the sample gas can be analyzed for volatile compounds. For this purpose, a detector detector is arranged in the detector measurement path, which is designed to continuously detect the presence of a group of volatile compounds. In this case, the sample gas and the carrier gas escape through the first exhaust port.

[0013] If highly volatile compounds were detected in the detector measurement path, the control element can, preferably automatically, adjust the pressure conditions in the gas analyzer so that the pressure in the separation measurement path is lower than in the detector measurement path. This directs a portion of the sample gas from the detector measurement path through the branching connection path into the separation measurement path. The concentrations of the individual compounds in the sample gas can be detected in the separation measurement path. In this case, the sample gas escapes through the second exhaust port.

[0014] Since only a portion of the sample gas flowing through the detector measurement path flows through the connecting path, the search for volatile compounds can continue while the individual concentrations of the volatile compounds are recorded. This accelerates the survey of large areas or large buildings. The invention further utilizes the measurement paths efficiently, thus avoiding a multiple structure. This reduces the weight and wear of the components of the gas analyzer. Furthermore, by avoiding a valve between the connecting path and the detector measurement path, maintenance of the portable gas analyzer is simplified and the service life of the device is increased, as the number of mechanical components is kept to a minimum.

[0015] Advantageously, the seeker detector is a photoionization detector, a semiconductor gas detector or a thermal conductivity detector.

[0016] The control element may advantageously be designed to automatically reverse the gas flow in the connection path when the presence of volatile compounds is detected.

[0017] Furthermore, the separation detector is advantageously designed for determining the quantity of volatile compounds and is preferably a gas chromatograph in combination with a photoionization detector, a thermal conductivity detector, a semiconductor gas detector, or a mass spectrometer. For this purpose, it is expedient for the separation detector to comprise a separation column, wherein the separation column is designed as a multi-capillary column. The separation column acts as a retention element through which the individual volatile compounds flow at different velocities. The multi-capillary leads to higher gas volume flow (stronger signals) and consequently lower detection limits. In combination with the shortness of the column (and its material properties), this leads to rapid analyses. Thus, the determination of the concentration of a volatile compound is very rapid and can be carried out in less than 30 seconds.This is a great advantage, especially for portable gas analysis devices, as it allows for quick measurement results to be obtained directly on site.

[0018] Preferably, the first exhaust vent and the second exhaust vent are combined within a housing to form a common exhaust vent. Thus, the separation measurement path and the detector path share a common exhaust vent. This allows the gas analysis device to be designed even more compactly, which can be a significant application advantage, especially for portable use.

[0019] For practical purposes, the entire analytical path—formed by the finder measurement path, the separation measurement path, the separation detector, and the connecting path—is designed to be valve-free. Eliminating valves in this area effectively counteracts the risk of accumulations in the valve area that could distort the analysis. Furthermore, this increases the measurement speed and reduces wear.

[0020] A filter path advantageously branches off from the connecting measurement path and is connected to the carrier gas inlet opening, with a filter element arranged in the filter path. The filter element is used to filter out highly volatile compounds from the carrier gas flowing through the carrier gas inlet opening. The filtered carrier gas can then be used as purge gas in the separation measurement path to flush out any residual sample gas from the last measurement between two measurements of the individual concentrations. If the pressure in the separation measurement path is higher than in the detector path, the carrier gas can first flow through the filter element from the carrier gas inlet opening. The carrier gas then flows through the separation measurement path. At the same time, the carrier gas can flow through the connecting path into the detector measurement path. The filter path can be designed as a bypass to the separation detector.If the pressure in the separation measurement path is lower than in the finder measurement path, no carrier gas passes from the filter path into the connection path.

[0021] For this purpose, the control element is expediently designed, in a first advantageous embodiment, as a valve configured to open and close the filter path. In this case, after the filter path is closed, the carrier gas is directed directly from the carrier gas inlet through the second exhaust air opening. In another embodiment, the carrier gas flow can be blocked at the carrier gas inlet, so that the carrier gas does not flow into the gas analysis device or the filter path at all.

[0022] In a second advantageous embodiment, the control element is designed as a controllable blower unit at the carrier gas inlet opening, at the first exhaust air opening, and / or at the separation detector. By increasing or decreasing the blower power, the pressure in the finder measurement path or in the separation measurement path is influenced. The controllable blower unit can thus adjust the pressure in the separation measurement path relative to the finder measurement path. In this case, either the pressure in the finder measurement path or in the separation measurement path can be changed. If controllable blower units are arranged in both the finder measurement path and the separation measurement path, the pressures in the finder measurement path and in the separation measurement path can be changed in opposite directions such that the gas flow direction in the connecting path is reversed.However, it can also be provided that a first controllable blower unit is arranged at the first exhaust air opening as a flow generating element, wherein the first controllable blower unit generates a gas flow in the direction of the first exhaust air opening, and a second blower unit is arranged between the separation detector and the second exhaust air opening, which generates a gas flow from the connecting path through the separation detector in the direction of the second exhaust air opening. The direction of the gas flow in the connecting path is thus determined by means of the blower units. For this purpose, it is further expedient if a flow or pressure difference sensor is arranged at the carrier gas inlet opening, wherein the power of the blower unit at the separation detector is regulated depending on the measurement of the flow or pressure difference sensor. The control of the blower units can thus be regulated based on the carrier gas flow.In both embodiments, the control of gas flows in the gas analysis device is simplified because complex valve and fan controls can be dispensed with.

[0023] Further advantages of the finder with a finder detector are faster response times and reduced wear due to contamination of the separation detector. Thanks to the finder, the fans on the device can be operated continuously, limiting the stabilization of the power to a short warm-up phase. In an advantageous design, the power can then be stabilized or modulated via a control loop with a flow sensor. The finder can trigger the reversal of the gas flow and thus injection for the separation measurement without warm-up, pre-purging, or similar process steps. During operation before and after injection, the device cleans itself in the finder path, the connection path, and after the separation measurement has been completed, also in the separation measurement path. All of these are advantageously designed without valves, which would increase the accumulation of substances.By preventing contamination of the gas paths, wear is reduced and component lifespan is increased. Continuous operation of the fans also stabilizes heat generation within the device, preventing sudden heating in the separation detector area during measurement, which would severely distort the results in a gas chromatograph, for example.

[0024] Furthermore, the gas analysis device advantageously comprises a location module designed to determine the geographical coordinates of the gas analysis device and preferably connected to the control element via a signal connection. The location coordinates can be conveniently stored on a storage unit together with the measurement data on the total and individual concentrations.

[0025] Advantageously, the gas analysis device comprises an internal evaluation unit which is designed to evaluate the measurement data.

[0026] The invention further relates to a system comprising a portable gas analysis device according to the preceding description, with an internal evaluation unit, and an external evaluation unit. According to the invention, the internal evaluation unit and the external evaluation unit are configured to exchange control commands and measurement data via a wireless signal connection. An external evaluation unit can be easily upgraded and generally has greater computing power and more advanced display options than internal evaluation components.

[0027] Furthermore, the invention relates to a gas analysis method using a portable gas analysis device according to the preceding description, comprising the steps of: setting a higher pressure in the separation measuring path relative to the searcher measuring path, detecting the presence of a highly volatile compound from a group of highly volatile compounds in the searcher measuring path by means of the searcher detector, setting a lower pressure in the separation measuring path relative to the searcher measuring path, separating the individual members of the group of highly volatile compounds, determining the amount of the separated highly volatile compounds, wherein preferably the detection of the presence of the highly volatile compounds is continued continuously during the separation and the determination.

[0028] In this case, a request signal is advantageously transmitted automatically based on the detection of the presence of highly volatile compounds. Advantageously, a lower pressure is set in the separation measurement path relative to the finder measurement path after the transmission of a request signal. The geographical coordinates of the location where the separation and quantity determination are performed are expediently determined and stored.

[0029] The invention is explained in more detail below with reference to the accompanying drawings using advantageous embodiments. They show: Fig. 1a,b,c a perspective view of various embodiments of a portable gas analysis device with an external evaluation unit; Fig. 2a,b,c a schematic representation of the components of a portable gas analysis device according to the invention with various embodiments of the control element; Fig. 3 a schematic representation of the components in an alternative embodiment of the filter path; Fig. 4a,b,c a schematic representation of the internal or external evaluation unit and its connection to the detectors and, if applicable, wireless connection to control and screen elements; Fig. 5a,b a schematic representation of the components and gas paths in an alternative embodiment with a pressure difference sensor in two states depending on a valve position; and Fig. 6 a schematic representation of the components and gas paths in relation to gas path constrictions, pressure difference sensor and combined exhaust air opening.

[0030] The portable gas analysis device is designated in its entirety by the reference numeral 1. The gas analysis device 1 has a housing 13 on which a sample gas inlet opening 20 and a carrier gas inlet opening 40 are arranged.

[0031] In a first embodiment, as shown in Fig. 1a As shown, the gas analysis device has a compact housing 13. Furthermore, the compact housing 13 has an operating element 10 and a screen element 12 and is connected to an external evaluation unit 9 via a wireless connection 91. The operating element 10 and screen element 12 can preferably be combined, in the form of a touch-sensitive display ("touch screen"). Optionally, the housing 13, as in Figur 1a As shown, it can be pistol-shaped, with the extension 14 being shaft-shaped. However, this is not necessary; the housing can also be cuboidal, for even greater compactness.

[0032] In a further embodiment, the control element 10 and the screen element 12 are arranged externally, preferably together with the evaluation unit 9 in a second housing 92. In a first preferred embodiment according to Figur 2a A search measurement path 2 extends from the sample gas inlet opening 20 to a first exhaust air opening 21. A first controllable blower unit 23 is also arranged at the first exhaust air opening 21 as a flow generating element. The first controllable blower unit 23 generates a gas flow in the direction of the first exhaust air opening 21. Sample gas is thus sucked in by the first controllable blower unit 23 from the sample gas inlet opening 20, which is then guided via the search measurement path 2 to the first exhaust air opening 21. The search measurement path 2 further comprises a search detector 22. The search detector 22 is a photoionization detector. A portion of the sample gas flow is directed to the search detector 22. The search detector 22 continuously performs a measurement with which it can be determined whether highly volatile compounds are contained in the sample gas.

[0033] A connecting path 3 branches off from the detector measurement path 2. A separation measurement path 4 extends from the connecting path 3 to a second exhaust air opening 41. A separation detector 42 is arranged in the separation measurement path 4. The separation detector 42 is a gas chromatograph comprising a multi-capillary column as the separation column 420. A large volume of gas can be passed through a multi-capillary column. In this way, large quantities of sample gas can be passed to the separation detector 42 and retained. The other components of the gas analysis device 1 do not cause retention. The path formed by the detector measurement path 2, the connecting path 3, and the section of the separation path between the connecting path 3 and the separation detector 42 is referred to as the "analytical path." The analytical path is free of valves, i.e., it is valveless.

[0034] After approximately 30 seconds, the entire sample gas has passed through the separation detector 42 and the separation measurement path 4 has been purged with carrier gas, so that a new measurement of the individual concentrations can begin without pre-loading from the previous measurement. The separation detector 42 is further configured to determine benzene concentrations with a sensitivity of 25 ppb.

[0035] Viewed from the connecting path 3, a second blower unit 43 is arranged behind the separation detector 42. The blower unit 43 generates a gas flow from the connecting path 3 through the separation detector 42 toward the second exhaust air opening 41.

[0036] Furthermore, the separation measurement path 4 is connected to the carrier gas inlet opening 40 so that carrier gas can be fed into the separation measurement path 4. A third blower unit 44 is arranged at the carrier gas inlet opening 40, which generates a gas flow from the carrier gas inlet opening 40 toward the separation measurement path 4.

[0037] A filter path 6 branches off from the connection path 3 as a bypass to the separation detector 42. The bypass connects the separation measuring path 4 with the connection measuring path 3. The separation measuring path 4 and the filter path 6 form a circuit.

[0038] The filter path 6 further comprises a filter element 60. The filter element 60 is designed to filter out highly volatile compounds. As the carrier gas flows through the filter element 60, all highly volatile compounds are filtered out, so that the carrier gas no longer contains any highly volatile compounds after passing through the filter element 60.

[0039] At the connection between the separation measuring path 4 and the filter path 6, a valve 5 is arranged as a control element. The valve 5 is arranged upstream of the second exhaust air opening 41. The valve 5 switches between the filter path 6 and the second exhaust air opening 41. This means that in one switching position, no gas flow is permitted through the second exhaust air opening 41. In this case, the gas flow is introduced from the separation measuring path 4 into the filter path 6. In this embodiment, the second and third blower units 43, 44 generate a stronger gas flow overall than the first blower unit 23. A portion of the filtered carrier gas from the filter path 6 is guided into the separation measuring path 4 and purges the separation detector 42. The carrier gas remains in the circuit formed by the separation measuring path 4 and the filter path 6.

[0040] The other part of the gas flow from the filter path 6 is directed through the connecting measurement path 3 into the finder measurement path 2. The first blower unit 23 is configured to direct the combined gas flow from the connecting measurement path 3 and the finder measurement path 2 out of the first exhaust port 21. This prevents the carrier gas from being blown out through the sample inlet port 20.

[0041] When valve 5 blocks filter path 6, the circuit between separation measurement path 4 and filter path 6 is interrupted. Furthermore, the carrier gas flowing in from carrier gas inlet 40 is directed directly to the second exhaust port 41. Thus, no gas is directed from filter path 6 into connection measurement path 3. As a result, sample gas now flows from finder measurement path 2 through connection measurement path 3. The direction of gas flow in connection measurement path 3 is thereby reversed.

[0042] From the compound measurement path 3, the sample gas flows into the separation measurement path 4 and thus through the separation detector 42. The separation detector 42 separates various compounds in the sample gas mixture so that their concentrations can be measured separately. Since sample gas continues to flow in the detector measurement path 2 from the sample gas inlet opening 20 to the first exhaust air opening 21, the detector detector 22 continues to be supplied with sample gas. This prevents the measurement of the detector detector 22 from being interrupted while determining the individual concentrations of the volatile compounds in the separation measurement path 4.

[0043] In a second preferred embodiment according to Figur 2b No valve is provided between the filter path 6 and the finder measuring path 4. Instead, the control element is formed by the third controllable blower unit 44. The direction of the gas flow in the connecting measuring path 3 is controlled in this embodiment by the blower power of the third controllable blower unit 44. When the third controllable blower unit 44 is controlled at high power, the gas flow is directed through the second exhaust air opening 41 and into the filter path 6. The blower power of the third controllable blower unit 44 is so high that the gas flow from the filter path 6 is directed both into the connecting measuring path 3 and into the separating measuring path 4. To reverse the gas flow in the connecting measuring path 3, the power of the third controllable blower unit 44 is reduced to such an extent that no or only very little carrier gas is introduced into the filter path 6. As a result, no carrier gas is introduced from the filter path 6 into the connection measuring path 3.Instead, sample gas is directed from the finder measurement path 2 into the connection measurement path 3, so that a reversal of the gas flow in the connection measurement path 3 takes place.

[0044] In an alternative embodiment, the filter path 6 is not provided as a bypass to the separation detector 42. The separation measurement path 4 and the filter path 6 do not form a circuit in this embodiment. In this embodiment, the filter path 6 branches off from the connecting path 3 and extends to the carrier gas inlet opening 40. The filter path 6 comprises the filter element 60. The third blower unit 44 is arranged at the carrier inlet opening 40 as a control unit. The third blower unit 44 directs carrier gas from the carrier gas inlet opening 40 toward the connecting path 3. The direction of the gas flow in the connecting path 3 can be controlled by adjusting the third controllable blower unit 44 up and down.

[0045] Instead of the third controllable fan unit 44, the first controllable fan unit 23 or the second controllable fan unit 43 can also function as the control element. Furthermore, a combination of the controllable fan units 23, 43, and 44 can also be used as the control element. The fan units 23, 43, and 44 function as flow-generating elements.

[0046] In embodiments in which the control element is formed by at least one of the controllable blower units 23, 43, 44, a flow sensor 45 can be provided at the carrier gas inlet opening 40. The flow sensor 45 measures the amount of carrier gas flowing through the carrier gas inlet opening 40 into the separation measurement path 4. The controllable blower units 23, 43, 44 can be controlled based on the flow rate of the carrier gas in order to achieve a reversal of the gas flow in the connection path 3.

[0047] Furthermore, a locating module 7 is provided, which is designed to determine the geographical position of the portable gas analysis device 1. The locating module 7 is connected to the control element via a locating signal line 71. The locating module 7 can transmit the position signal to the control element via the locating signal line 71. The position signal can then be stored in a memory unit (not shown), which is connected to an internal evaluation unit 8, together with the measurement data from the detectors 22, 42. The detectors 22, 42 are connected to the internal evaluation unit 8 via data lines 81 (see Figur 4 ). In this way, the measurement data of the detectors 22, 42 can be linked with the position data, so that a spatial resolution of the measurement data can be achieved with several measurements at different geographical positions.

[0048] The control element 10 is further connected to the control element via a trigger signal line 11. A user can manually request a reversal of the gas flow in the connection path 3 via the control element 10. This can trigger a measurement of the individual concentrations of the volatile compounds. Alternatively, the measurement of the individual concentrations can be triggered automatically when the search detector 22 detects an increased total concentration of volatile compounds.

[0049] The acquired measurement data can be transmitted from the evaluation unit 8 to the display element 12 via a signal connection 81. The display element 12 can display this measurement data to the user. The user thus receives the measurement data on-site. The display element 12 is updated with a cycle of less than 1 second, i.e., it displays the current measurement progress by the separation detector 42 or the finder detector 22. After approximately 10 seconds of measurement, the user can therefore already decide whether an evaluable data set is available or not.

[0050] In a further embodiment, an external evaluation unit 9 can be provided in addition to the internal evaluation unit 8. The measurement data of the detectors 22, 42 are applied to the internal evaluation unit via data connections 81 and further transmitted to the external evaluation unit 9 via a wireless connection 91. The control element 10 and the screen element 12 are connected to the internal evaluation unit 8 and / or the external evaluation unit 9 via data connections 81. Exemplary designs of housings and signal connections are shown in Fig. 1b combined with Fig. 4b or Fig. 1c combined with Fig. 4c illustrated.

[0051] It should be noted that, if desired, the exhaust air openings 21, 41 can be combined to form a common exhaust air opening 31. This represents a further advantageous simplification and enables a very compact design, as in Fig. 1c as well as Fig. 2c illustrated.

[0052] To determine the individual concentrations of the volatile compounds, the gas flow in the connecting path 3 is reversed for approximately 1 second. The amount of sample gas extracted in this way is usually sufficient for one measurement by the separation detector 42. Due to the short sampling time, a user can use the gas analysis device 1 to locate additional locations where volatile compounds are suspected and detect them using the search detector 22.

[0053] In an alternative embodiment, a flow or pressure difference sensor 46 is arranged above the separation detector 42, wherein a flow sensor directly or a pressure difference sensor indirectly measures the gas flow generated by the controllable blower unit 43. The pressure difference is the direct cause of the gas flow. The blower 43 is controlled by the internal evaluation unit 8 depending on the measurement at the pressure difference sensor 46. A blower unit 23 generates a continuous gas flow in the searcher measurement path 2 from the sample gas inlet opening 20 to the first exhaust air opening 21. For the injection of the separation measurement, its valve position and gas flows are shown schematically in Fig. 5b As shown, the gas flow in the connecting piece 3 is directed from the search measuring path 2 into the separation measuring path 4, thus injecting sample gas from the sample gas inlet opening 20 into the separation column 420 of the separation detector 42. In another position on the valve 5, which is set before and after the injection, the separation measuring path 4 is purged with carrier gas filtered in the filter 60 from the filter path 6, whereby the carrier gas can be combined with the gas flow from the separation detector to form a stronger gas flow, as shown in Fig. 5a Preferably, the power of the adjustable blower unit 43 is controlled depending on the measurement at the flow or pressure difference sensor 46 so that a predetermined pressure difference and thus a specific gas flow through the separation column 420 is generated. If the same gas flows are set for successive measurements, the measurements are more easily comparable.

[0054] In an alternative embodiment of the gas analysis device, shown schematically in Fig. 6, the carrier gas inflow is passive, i.e., without a third blower unit 44. Furthermore, the seeker measurement path 2 is shown in a design without a seeker detector 22, which is not covered by the claims. The omission of the third blower unit 44 can also be provided for in the other embodiments, if necessary. This eliminates an active component, thereby reducing manufacturing costs, energy consumption, heat generation, and the risk of failure. The gas flow in paths 2, 3, 4, 6, 21, 41 is determined by pressure differences in the gas path system, which are generated by the two blower units 23, 43. Narrowings of the gas paths 52, 53, 54 are designed to passively reduce the flow, whereby the desired flow directions are achieved at suitable speeds and without backflows. The gas path constrictions 52, 53, 54 can be implemented by suitable diameters of the hoses or gas flow restrictions.A blower unit 23 generates a continuous gas flow in the detector measuring path 2 from the sample gas inlet opening 20 via the first exhaust air opening 21 to the common exhaust air opening 31. In a first position on the valve 5, the carrier gas inlet opening 40 is connected to the filter path 6 and the separation measuring path 4. The power of the blowers 23, 43 and the diameters of the gas path constrictions are selected such that the gas flow in the connecting path 3 from the filter path 6 into the detector measuring path 2 is stronger than the gas flow from the filter path 6 into the separation measuring path 4. The volume formed from the circuit of the separation measuring path 4 and filter path 6 has two connections in this valve position, one to the connecting path 3 and one to the carrier gas inlet opening 40. Since the gas flow in the connecting path 3 is directed towards the detector measuring path 2, carrier gas must be sucked in at the carrier gas inlet opening 40.The gas path constriction 53 additionally prevents turbulent flow at this point, which could cause a temporary backflow. A flow or pressure difference sensor 46 monitors the state of the gas flow in the separation measuring path 4, whereby the power of the blower unit 43 is regulated to achieve a specific gas flow. In a second position on the valve 5, the carrier gas inlet opening 40 and the separation measuring path 4 are connected to the second exhaust opening 41, and the connection to the filter path 6 is interrupted. The gas flow from the sample gas inlet opening 20 is always directed towards the finder measuring path 2 and from there via two paths to the common exhaust opening 31. This ensures that a closed sample volume is not contaminated or diluted and that gas only leaves the device via the exhaust openings 21, 41 or the common exhaust opening 31.The first path runs from the finder measuring path 2 via the blower unit 23 and the first exhaust air opening 21. The second path runs via the finder measuring path 2 into the now reversed flow in the connecting path into the separation measuring path 4, where sample gas is injected into the separation detector 42. In this second valve position, the gas flow at the carrier gas inlet opening 40 is also redirected, since part of the gas flow from the separation measuring path 4 flows out there. Preferably, the carrier gas in this embodiment is air, or the gas path constriction 53 is selected such that the carrier gas volume outside the carrier gas inlet opening 40 is not excessively contaminated by this flow from the separation measuring path 4. The majority of the exhaust air from the separation measuring path 4 flows into the second exhaust air opening 41. In the example, the two exhaust air openings 21, 41 are combined as a common exhaust air opening 31 on the housing 13.In this embodiment, the advantages of the inventive connection of the finder measurement path 2 and the separation measurement path 4 via the connecting path 3 are achieved even with few active components, since these paths are all designed without valves and the continuous operation of the blower 23 in the finder and, in the second valve position, the counter-purge with filtered carrier gas through the connecting path 3 into the finder measurement path 2 each prevent an enrichment of the gas paths with volatile compounds. The continuous operation of the two blower units 23, 43 stabilizes their performance compared to a switch-on process at the beginning of the measurement. By controlling the performance of the blower 43 depending on the measurement of the pressure difference sensor 46, the gas flow is further stabilized and is only influenced by the position of the valve 5 outside the analytical path.The measuring device is therefore very stable in its operation overall, which makes consecutive measurements and signal values ​​within a measurement at the separation detector easier to compare. In the second valve position, the device is in standby mode, in which there is always a gas flow from the sample gas inlet 20 into the finder measurement path 2. After the separation measurement is triggered at the control element 10, the valve 5 is switched without delay and the flow in the connecting path 3 is reversed, so that sample gas is injected directly from the controlled gas flow in the finder measurement path 2 into the separation measurement path 4 and the separation measurement begins. Approximately one second passes between the triggering of the measurement and the end of the injection. Without the finder, the sample would have to be injected from a stagnant volume outside the device, a more time-consuming and less controllable solution that does not meet the requirements.

Claims

1. Gas analysis device for the passage of a gas flow, in particular for volatile compounds, the gas analysis device comprising a finder measurement path (2) and a separation measurement path (4), the finder measurement path (2) extending from a sample inlet opening (20) to a first exhaust air opening (21), a connecting path (3) branching off from the finder measurement path (2) to the separation measurement path (4), the separation measurement path (4) extending from the connecting path (3) to a second exhaust air opening (41) and being connected to a carrier gas inlet opening (40), and a separation detector (42) being arranged on the separation measurement path (4), characterized in that the gas analysis device (1) is portable and has a control element (5, 23, 43, 44) which is designed to reverse the gas flow in the connecting path (3) such that, in the reverse direction, a part of a sample gas mixture entering at the sample inlet opening flows via the connecting path (3) into the separation measurement path (4) and the other part follows the finder measurement path (2), a finder detector (22) being arranged in the finder measurement path (2), which finder detector is designed to continuously ascertain the presence of a group of volatile compounds.

2. Portable gas analysis device according to claim 1, characterized in that the separation detector (42) is designed to determine the quantity of volatile compounds and is preferably a gas chromatograph having a photoionization detector, a thermal conductivity detector, a semiconductor gas detector or a mass spectrometer.

3. Portable gas analysis device according to either claim 1 or claim 2, characterized in that the separation detector (42) comprises a separation column (420), the separation column (420) being designed as a multi-capillary column.

4. Portable gas analysis device according to any of claims 1 to 3, characterized in that the finder measurement path (2), the separation measurement path (4) up to the separation detector (42) and the connection path (3) are each designed without valves.

5. Portable gas analysis device according to any of claims 1 to 4, characterized in that the finder detector (22) is a photoionization detector, a semiconductor gas detector or a thermal conductivity detector.

6. Portable gas analysis device according to any of claims 1 to 5, characterized in that the first exhaust air opening (21) and the second exhaust air opening (41) are combined within a housing (13) to form a common exhaust air opening (31).

7. Portable gas analysis device according to any of claims 1 to 6, characterized in that a filter path (6) branches off from the connecting path (3), a filter element (60) being arranged in the filter path (6) and the filter path (6) being connected to the carrier gas inlet opening (40).

8. Portable gas analysis device according to claim 7, characterized in that the control element (5) is designed as a valve, which is designed to open and close the filter path (6).

9. Portable gas analysis device according to any of claims 1 to 7, characterized in that the control element (23, 43, 44) is designed as a controllable blower unit at the carrier gas inlet opening (40), at the first exhaust air opening (21) and / or at the separation detector (42).

10. Portable gas analysis device according to any of claims 1 to 7, characterized in that a first controllable blower unit (23) is arranged as a flow generating element at the first exhaust air opening (21), the first controllable blower unit (23) generating a gas flow in the direction of the first exhaust air opening (21), and a second blower unit (43) being arranged between the separation detector (42) and the second exhaust air opening (41), which second blower unit generates a gas flow from the connection path (3) through the separation detector (42) in the direction of the second exhaust air opening (41).

11. Portable gas analysis device according to any of claims 1 to 10, characterized in that a flow or pressure difference sensor (46) is arranged above the separation measurement path (4), the power of a blower unit at the separation detector (42) being controlled in a closed-loop manner by means of an evaluation unit (8) on the basis of the measurement of the flow or pressure difference sensor (46).

12. System comprising a portable gas analysis device (1) according to any of claims 1 to 11 having an internal evaluation unit (8) and an external evaluation unit (9), characterized in that the internal evaluation unit (8) of the gas analysis device (1) and the external evaluation unit (9) are designed to exchange control commands and measurement data by means of a wireless signal connection.

13. Gas analysis method using a portable gas analysis device (1) according to any of claims 1 to 11, comprising the steps of: setting a higher pressure in the separation measurement path (4) relative to the finder measurement path (2), ascertaining the presence of a volatile compound from a group of volatile compounds in the finder measurement path (2) by means of the finder detector (22), setting a lower pressure in the separation measurement path (4) relative to the finder measurement path (2) and separating the individual members of the group of volatile compounds.

14. Gas analysis method according to claim 13, characterized in that ascertaining the presence of the volatile compounds is carried out continuously during the separation and a determination.