METHOD FOR TESTING A GAS SENSOR AND GAS-MEASURING DEVICE WITH A TESTING DEVICE FOR TESTING A GAS SENSOR

Abstract

A method for testing a gas sensor and a gas-measuring device with a testing device for testing the gas sensor provides an improved analysis and evaluation of states of gas sensors. Due to a testing of a gas admission element, by monitoring measuring signals (35, (38) in a time course (400) in conjunction with dispensing (91, 91′, 91″) a quantity of test substance, it is made possible to check whether a gas supply to the gas sensor is possible (to check if the gas diffusion path is open) and given.

Claims

1. A method for testing at least one gas admission element of a gas sensor or of a gas-measuring arrangement with at least one gas sensor, the method comprising the steps of: providing a control unit to carry out a continuous measuring operation controlled by the control unit; with the control unit bringing about a dispensing of a quantity of test substance, by means of a test gas dispensing unit arranged downstream of the gas admission element and upstream of a sensor-measuring arrangement, to the sensor-measuring arrangement arranged in the gas sensor; with the control unit prompting a continuous detection of a plurality of measured signals of the gas sensor and prompting a storage of the plurality of measured signals, as a set of measured signals over a predefined detection time, in a memory and a storage of corresponding time information in the memory for at least some measured signals of the set of measured signals; with the control unit determining a maximum of the measured signals and determining a detection time of the maximum of the measured signals from the set of measured signals; with the control unit selecting at least one additional measured signal of the gas sensor, which is spaced in time and follows the detection time of the maximum of the measured signals from the set of measured signals, over a predefined detection time on the basis of the time information; with the control unit comparing the at least one additional measured signal with the maximum of the measured signals; and with the control unit determining, on the basis of the comparison of the maximum of the measured signals with the at least one additional measured signal, whether the gas admission element is ready to operate for a feed of air, gas or gas mixture from a measuring environment and determining an indicator of readiness of the gas sensor or of the gas-measuring arrangement with the at least one gas sensor or of both the gas sensor and of the gas-measuring arrangement with the at least one gas sensor to operate.

2. A method in accordance with claim 1, wherein the dispensing of the quantity of liquid test substance by the test gas dispensing unit to the sensor-measuring arrangement in the gas sensor is brought about by the control unit such that the control unit activates the test gas dispensing unit in a time course at a first, activation time.

3. A method in accordance with claim 1, wherein the dispensing of the quantity of liquid test substance by the test gas dispensing unit to the sensor-measuring arrangement in the gas sensor is brought about by the control unit such that the control unit activates the test gas dispensing unit for dispensing the quantity of liquid test substance in a time course at the first, activation time and the control unit deactivates the dispensing of the quantity of liquid test substance by the gas dispensing unit at a second, deactivation time, which second, deactivation time is spaced in time from and follows the first, activation time.

4. A method in accordance with claim 3, wherein a size or a volume or both a size and a volume of the gas sensor is taken into account by the control unit for the second, deactivation time in the time course.

5. A method in accordance with claim 1, wherein a size or a volume or both a size and a volume of the gas sensor is taken account by the control unit when dispensing the portion of liquid test substance by means of the test gas dispensing unit.

6. A method in accordance with claim 1, wherein a size or a volume or both a size and a volume of the gas sensor, a number of gas admission elements, a thickness of one or more gas admission elements, a pore size of one or more gas admission elements an area or a diameter of the gas admission element, or any combination of a size, a volume, a number of gas admission elements, a thickness of one or more gas admission elements, a pore size of one or more gas admission elements an area or a diameter of the gas admission element are taken into account by the control unit for setting the duration of the predefined detection time.

7. A method in accordance with claim 1, wherein a substitute signal is generated by the control unit for setting a time of an interruption of the continuous measurement for bringing about a dispensing of a quantity of test substance.

8. A method in accordance with claim 1, wherein a status signal is determined or provided by the control unit on a basis of the comparison of the at least one additional measured signal with the maximum of the measured signals or with the indicator of the readiness of the gas sensor or of the gas-measuring arrangement with the at least one gas sensor to operate.

9. A method in accordance with claim 8, wherein the status signal is provided by the control unit for an output unit, a central analysis system, a central alarm unit or a mobile display device and wherein an alarm signal or a message is outputted by the control unit, the output unit, the central analysis system the central alarm unit or the mobile output device.

10. A method in accordance with claim 9, wherein the alarm signal is provided by the output unit or by the control unit for an acoustic alarm generator for generating an acoustic alarm or for an optical signal generator for generating an optical or visually visible alarm.

11. A method in accordance with claim 9, wherein the message is provided by the output unit or by the control unit in a visible form on a display unit, a screen as an instruction, as a warning message or as an instruction in text form, graphic form or in a symbolic form.

12. A gas-measuring device comprising: at least one gas sensor with at least one sensor-measuring arrangement, wherein the gas sensor or the gas-measuring arrangement detects a gas concentration or a change in a gas concentration and comprises a gas admission element arranged upstream of the sensor-measuring arrangement; a test gas dispensing unit arranged downstream of the gas admission element in the gas sensor or in the gas-measuring arrangement; and a control unit and memory associated with the control unit wherein the control unit is configured to: bring about a dispensing of a quantity of test substance, by means of the test gas dispensing unit; prompt a continuous detection of a plurality of measured signals of the gas sensor and prompt a storage of the plurality of measured signals, as a set of measured signals over a predefined detection time, in the memory and store corresponding time information in the memory for at least some measured signals of the set of measured signals; determine a maximum of the measured signals and determine a detection time of the maximum of the measured signals from the set of measured signals; select at least one additional measured signal of the gas sensor, which is spaced in time and follows the detection time of the maximum of the measured signals from the set of measured signals, over a predefined detection time on the basis of the time information; compare the at least one additional measured signal with the maximum of the measured signals; and determine, on the basis of the comparison of the maximum of the measured signals with the at least one additional measured signal, whether the gas admission element is ready to operate for a feed of air, gas or gas mixture from a measuring environment and determining an indicator of readiness of the gas sensor or of the gas-measuring arrangement with the at least one gas sensor or of both the gas sensor and of the gas-measuring arrangement with the at least one gas sensor to operate.

13. A gas-measuring device in accordance with claim 12, wherein the test gas dispensing unit comprises a piezo dispensing element and a reservoir fluidically connected to the piezo dispensing element for storing a reserve quantity, wherein the control unit is configured to activate the piezo dispensing element at a first time.

14. A gas-measuring device in accordance with claim 12, wherein the test gas dispensing unit comprises a valve and a reservoir fluidically connected to the valve for storing the reserve quantity, wherein the control unit is configured to activate the valve at a first time and to deactivate the valve at a second time.

15. A gas-measuring device in accordance with claim 12, further comprising: an output unit; an optical alarm generator or an acoustic alarm generator or both an optical alarm generator and an acoustic alarm generator, wherein the optical alarm generator or the acoustic alarm generator are configured and provided to output an alarm signal in interaction with the control unit or with the output unit or both the control unit and the output unit.

16. A gas-measuring device in accordance with claim 14, wherein the output unit has an interface configured and provided to transmit the status signal to an analysis system in interaction with the control unit.

17. A gas-measuring device in accordance with claim 12, wherein the at least one sensor-measuring arrangement is configured as a combination of electrodes and an electrolyte in an electrochemical gas sensor; as a combination of radiation source and a detector element in an infrared optical gas sensor; as a combination of catalytically active or catalytically passive measuring elements or both catalytically active and catalytically passive measuring elements in a catalytic gas sensor or in a heat tone sensor; or as a gas species-specific and sensitive semiconductor element in a semiconductor gas sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0091] In the drawings:

[0092] FIG. 1a is a schematic view showing a gas-measuring arrangement with an optical gas sensor and with a testing device;

[0093] FIG. 1b is a schematic view showing a gas-measuring arrangement with a catalytic gas sensor and with a testing device;

[0094] FIG. 1c is a schematic view showing a gas-measuring arrangement with an electrochemical gas sensor and with a testing device;

[0095] FIG. 1d is a schematic view showing a gas-measuring arrangement with a semiconductor gas sensor; and

[0096] FIG. 2 is a graph of a typical course of a measured signal of a gas sensor during a testing with the testing device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0097] Referring to the drawings, FIGS. 1a, 1b, 1c as well as 1d show arrangements for gas measurement with a gas sensor and with a testing device. FIG. 1a shows a gas-measuring arrangement 1 with an optical gas sensor 300. The optical gas sensor 300 is configured as a cuvette with a multireflection cell, not shown in detail in this FIG. 1a for reasons of clarity. A radiation source and a detector element are arranged as a sensor-measuring arrangement in the multireflection cell. Light is radiated in the multireflection cell from the radiation source onto an opposite wall as well as to side walls, reflected from there and detected by the element after multiple reflections. The presence of a test gas to be measured, for example, methane, ethane, butane, propane, changes the absorption for the emitted light in the infrared wavelength range. This can be detected as a measurement effect of an attenuated signal on the detector element. The measurement effect of an attenuation of the emitted IR light by certain gases, for example, methane, ethane, butane, propane, and other hydrocarbons is thus obtained. The gas from a measuring environment 2 enters the optical gas sensor 300 via a gas admission element 8, for example, a semipermeable or permeable diaphragm, a protective grid or a flame protection disk, entering the measuring cuvette of the optical gas sensor 300. Only a single gas admission element 8 is shown in this FIG. 1a as an embodiment of the environmental/ambient gas supply 7 with a gas admission element 8.

[0098] In an embodiment of a gas-measuring arrangement 1 in a device in which a plurality of gas sensors are arranged as a gas sensor system 30, it is technically common and advantageous in many technical embodiments to provide a plurality of gas admission elements 8 arranged one after another in a row. It is thus conceivable that, downstream from the measuring environment 2, a first gas admission element acts as a flame protector or dust protector, followed by a second element preventing the entry of moisture and a third element 8 in the gas sensor proper protects, for example, the optical gas sensor 300 or a catalytic gas sensor 301 (FIG. 1b) or an electrochemical gas sensor 302 (FIG. 1c) or a semiconductor gas sensor 303 (FIG. 1d). The test gas dispensing unit 9 may be arranged both downstream of the measurement between the first and second gas admission elements, between the second and third gas admission elements 8 or between the third gas admission element 8 and the gas sensor system 30, 300. These embodiments with a plurality of gas admission elements and possible, suitable positions in which the test gas dispensing unit 9 is arranged are not shown in the gas-measuring arrangement 1 for the sake of clarity of this FIG. 1a. However, these possible embodiments are also covered in the sense of the present invention as arrangements of the test gas dispensing unit 9 at the gas sensor system 30. Such a gas supply (supply of environmental/ambient gas) 7 takes place from the measuring environment 2 towards the optical gas sensor 300.

[0099] A test gas dispensing unit 9 is arranged at the optical gas sensor 300 downstream of the gas admission element 8 in this gas-measuring arrangement 1 according to FIG. 1a. A quantity of liquid test substance 5 is dispensed by this test gas dispensing unit 9 from a test substance reserve 305, for example, from a tank 305 containing a reserve quantity 306. This quantity of test substance 5, injected in the liquid form, vaporizes, is atomized or evaporates in the gas sensor 300 to form a quantity of gaseous test substance 6, which is then located in the optical gas sensor 300 for the measurement. The test gas dispensing unit 9 is actuated by means of a control line 91 by a control unit 3 such that a predefined quantity of liquid test substance 5 is dispensed into the optical gas sensor 300 upstream of the gas admission element 8 at predefined times t.sub.1. In a preferred variant, the test gas dispensing unit 9 is configured as a piezo dispensing element. Such a piezo dispensing element is configured, combined with the test substance reserve 305, to dispense an exactly defined quantity of test substance each upon a single-time activation by means of a control signal 91′ (FIG. 2), without deactivation of the piezo dispensing element, for example, by an additional control signal 91″ (FIG. 2) or by an exactly defined duration of the control signal 91″ (FIGS. 2, 3), thus defined by a time control 44 (FIG. 3), being necessary.

[0100] The control unit 3 receives measured signals 35, 38 from the optical gas sensor 300 and from the detector element in the optical gas sensor 300. Furthermore, the control unit 3 controls the infrared optical radiator in the optical gas sensor 300 by means of a control line 33. The measured signal 35, as well as a measured signal pattern 38 based on the measured signal 35 are transmitted by the control unit 3 to an output unit 80 by means of a data or signal line 92. The output unit 80 is configured to actuate an acoustic alarm generator, for example, a horn 40, or an optical alarm generator, for example, a lamp 50, by means of the signal and data line 92. Furthermore, the output unit 80 is configured by means of an interface 81 to transmit data, analysis results, sensor signals, data signals or processed measured signals 35, 38 to an analysis system 70 via signal and data lines 92 as well as control lines 91. A data bank 71, which can log states and events of tests of the gas-measuring arrangement 1, is preferably arranged in the analysis system 70. An operating and display unit (user interface) 60 is connected by the output unit 80 via a signal and data line 92. The operating and display unit 60 has a display screen 61, on which error messages as well as instructions for a user, as well as measured signals or measured values can be displayed. The control unit 3 and the test gas dispensing unit 9 cooperate in conjunction with a memory 32 arranged in the control unit 3 or with a memory 32 associated with the control unit 3 in a method for testing the gas-measuring arrangement 1, as is explained in more detail in FIGS. 2 and 3. The response of the optical gas sensor 300 to the dispensing of a quantity of liquid test substance 5 with evaporation of the quantity of liquid test substance 5 into a quantity of gaseous test substance 6 into the optical gas sensor 300 is used to check the time during which this dispensed quantity of test substance 5 diffuses again from the optical gas sensor 300 via the gas admission element 8. It is determined for this by the control unit 3 on the basis of detected measured signals with respect to a maximum of the measured signals whether the dispensed quantity 5, 6 has escaped from the optical gas sensor 300 after a certain time or not. If this dispensed quantity of test substance 5, 6 has not escaped from the optical gas sensor 300 after a predefined time, it can be inferred or determined by the control unit 3 that an incorrect situation is occurring at the gas admission element 8.

[0101] FIG. 1b shows a modified gas-measuring arrangement 1′ compared to FIG. 1a. Instead of the optical gas sensor with an infrared multireflection cell 300, a catalytic gas sensor 301 is shown in FIG. 1b. Such a catalytic gas sensor 301, also known as heat tone sensor, is connected to a control unit 3 and to a test gas dispensing unit 9, similarly to what is described in FIG. 1a in connection with the optical gas sensor 300. Identical elements in FIGS. 1a and 1b are designated by the same reference numbers in FIGS. 1a and 1b.

[0102] The description of the functionality and the interaction of the control unit 3 with the test gas dispensing unit 9 can also be extrapolated, as is explained in connection with FIG. 1a, to the functionality of the interaction of the control unit 3 and the catalytic gas sensor 301 with inclusion of the test gas dispensing unit 9 for testing the gas admission element 8.

[0103] The elements shown in FIG. 1a, namely, the output unit 80, the analysis system 70 and the operating and display unit 60 with the corresponding additional elements, as well as the data lines 92, as well as control lines 91 are not shown in detail in FIG. 1b. It is, however, implied in the sense of the present invention that the gas-measuring arrangement 1′ can interact with the analysis system 70, the analysis unit 80 and the operating and display unit 60 in a similar manner as is described in connection with FIG. 1a concerning the gas-measuring arrangement 1. The control lines 91 and data lines 92 are indicated schematically in a simplified manner only in this gas-measuring arrangement 1′.

[0104] Unlike in FIG. 1a with the gas-measuring arrangement 1, this gas-measuring arrangement 1′ shown in FIG. 1b shows the aspect that another gas sensor system 30, configured as one or two catalytic measuring elements as a sensor-measuring arrangement, is arranged in the catalytic gas sensor 201, and if a special gas, for example, ethane, methane, butane or propane is fed, these elements engage in a chemical reaction with this gas. A part of the gas is consumed during this reaction at the catalytic measuring elements. This has the effect that a dispensed quantity of test substance 5, 6 will not escape completely into the measuring environment 2 after a predefined time through the gas admission element 8, but there is a shortage, which is due to the consumption of measured gas by the catalytically active measuring elements in the catalytic gas sensor 301. This effect is to be taken into account when testing the gas-measuring arrangement 1′ or when testing the gas admission element 8 by means of the quantities of test substance 5, 6 entering by dispensing or diffusion and the escaping quantities of gas after a certain time. This is explained in more detail in FIG. 2 and the corresponding description.

[0105] FIG. 1cshows a gas-measuring arrangement 1″ with an electrochemical gas sensor 302. Elements that are identical in FIGS. 1a, 1b, and 1c are designated by the same reference numbers in FIGS. 1a, 1b, and 1c. Unlike in FIG. 1a with the gas-measuring arrangement 1, the gas-measuring arrangement 1″ in this FIG. 1c shows the aspect that another gas sensor system 30, configured as a sensor-measuring arrangement, preferably comprising a liquid electrolyte and an arrangement of electrodes in the electrochemical gas sensor 302, is arranged . An electrochemical reaction or chemical reaction tales place at the electrodes when feeding a special gas, for example, ammonia. The gas-measuring arrangement 1″ is shown in a similarly simplified manner as the gas-measuring arrangement 1′ according to FIG. 1b. Comments made in connection with this simplified view in the description of FIG. 1a can also be extrapolated to this FIG. 1c. It should be noted concerning the interaction of the control unit 3 with the test gas dispensing unit 9 and with the electrochemical gas sensor 302 that a gas sensor system 30 with an electrochemical gas sensor 302 also consumes a certain quantity of test gas during the measurement, similarly to a catalytic gas sensor 301 according to FIG. 1b, due to the chemical reaction taking place at the electrodes. This should also be taken into account in this embodiment according to FIG. 1c when testing and setting up the balance of the dispensed quantities of test substance 5, 6 and the quantities of gas escaping through the gas admission element 8. This is described in more detail in FIG. 2 as well as in the description of FIG. 2.

[0106] FIG. 1d shows a gas-measuring arrangement 1′″. This gas-measuring arrangement l′″ has a semiconductor sensor 303 as a gas sensor system 30. The explanations given in connection with FIGS. 1a, 1b, and 1c are correspondingly also applicable to FIG. 1d. The gas-measuring arrangement l′″ is explained in a simplified view comparable to FIGS. 1b and 1c. Identical elements in FIGS. 1a, 1b, 1c and 1d are designated by the same reference numbers in FIGS. 1a, 1b, 1c and 1d. The semiconductor sensor 303 is shown in FIG. 1d as a gas sensor system 30. The test gas dispensing unit 9 is shown as an interaction of a test substance reserve 305 with a valve 304 as another difference. This valve 304 is actuated by means of the control line 91 by the control unit 3. Similarly to what was described before in connection with FIGS. 1a, 1b, 1c, a reserve quantity 306 is contained in the test substance reserve 305. The reserve quantity 306 in this FIG. 1d is preferably a liquid gas, which is contained under pressure in the test substance reserve 305. When the valve 304 is opened for a predefined time, a portion of the reserve quantity 306 can enter the semiconductor sensor 303 from the test substance reserve 305. Depending on the value of the overpressure in the test substance reserve 305, a portion of the reserve quantity 306 enters the semiconductor sensor 303 as a quantity of liquid test substance 305 or as a quantity of already evaporated test substance 6. The transition from the liquid phase of the quantity of test substance 5 to the gaseous phase of the quantity of test substance 6 may take place directly due to pressure release when opening the valve 304, as well as when the quantity of liquid test substance 5 impinges on or impacts the walls of the semiconductor sensor 303. The interaction of the control unit 3 with the test gas dispensing unit 9 and the valve 304 and the test substance reserve 305 is described in detail in the description of FIG. 2 as well as in the process shown in FIG. 3 and in the corresponding description of the process according to FIG. 3.

[0107] FIG. 2 shows a typical pattern of a measured signal of a gas-measuring arrangement with a gas sensor during a testing with a testing device. Three diagrams 21, 22 are shown, which represent each a time curve t 400 synchronized with one another.

[0108] A measured signal pattern 38 with a common signal rise and with differences in the signal pattern 38′, 38″ and 38′″ is shown in a first diagram 21 as a signal pattern of a measured signal S 35. The measured signal S 35 is scaled on the ordinate. A maximum A.sub.Max of the measured signals, a measured signal A selected as an example and exemplarily in the signal rise and measured signals A′ selected as examples in the signal pattern 38′, A″ in the pattern 38″ and A′″ are shown in a first diagram. The pattern of the control signal 91 is shown over the time course t 400 in the second diagram 22. The control signal 91 is generated by the control unit 3 (FIGS. 1a, 1b, 1c and 1d). The control signal S 35 shows a base signal, which represents the absence of test gas or harmful gas, at the time t.sub.0 410.

[0109] A switching signal 91′ is sent by the control unit 3 (FIGS. 1a, 1b, 1c and 1d) at a time t.sub.1 401 to the test gas dispensing unit 9 (FIGS. 1a, 1b, 1c and 1d) to dispense or inject a quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d) to the gas sensor 300, 301, 302, 303 (FIGS. 1a, 1b, 1c and 1d) as a liquid quantity. The quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d) then evaporates into a quantity of gaseous test gas and is thus available as a test gas for detection by the sensor-measuring arrangement by the gas sensor system 30 (FIGS. 1a, 1b, 1c and 1d). At the time t.sub.2 402, the test gas dispensing unit 9 (FIGS. 1a, 1b, 1c and 1d) is deactivated again by another control signal 91′, so that no additional quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d) is dispensed to the gas sensor system 30 (FIGS. 1a, 1b, 1c and 1d). The measured signal S 35 responds to the dispensing of the quantity of test substance 6 (FIGS. 1a, 1b, 1c and 1d) with a signal rise. The signal rise corresponds to the current change in the gas concentration, caused by the dispensed quantity of gaseous test substance 6 (FIGS. 1a, 1b, 1c and 1d). The signal rise 38 following later reaches a maximum A.sub.Max of the measured signals S 35.

[0110] In the meantime, the dispensing of the quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d) was ended by means of the control signal 91″. In case of unhindered inflow and outflow (normal case) through the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d), the measured signal S 35 drops over time after the maximum A.sub.Max. In case the gas admission element 8 (FIGS. 1a, 1d) shows a blockage or an occlusion in the gas supply 7 (FIGS. 1a, 1d) in case of an optical gas sensor 300 (FIG. 1a ) or of a semiconductor sensor 303 (FIG. 1d), a signal pattern 38′″ is obtained.

[0111] In case the gas admission element 8 (FIGS. 1b, 1c) has a blockage in case of a catalytic gas sensor 301 (FIG. 1b ) or of an electrochemical gas sensor 302 (FIG. 1c), a signal pattern 38′″ is obtained.

[0112] The second diagram 22 shows the pattern of the control signal 91 over the time course t 400. This time course t 400 of the second diagram 22 is shown synchronously with the time course t 400 of the first diagram 21. Beginning with a time t.sub.0 410, a control signal 91′, which brings about the dispensing of the quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d), is activated at a time t.sub.1 401. The deactivation of the dispensing of the quantity of test substance 5 (FIGS. 1a, 1b, 1c and 1d) by means of the control signal 91″ takes place at the time t.sub.2 402.

[0113] In the first diagram 21, the measured signal pattern 38′″ shows a pattern that belongs to a sensor-measuring arrangement with an optical gas sensor 300, a decaying measured signal S 35, because an optical gas sensor 300 has no measured gas consumption. As a result, the measured signal S 35 remains nearly constant after dispensing if no gas can escape from the gas sensor 30 (FIGS. 1a, 1b, 1c and 1d) into the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d). The pattern according to 38′″ thus shows a drop at which the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d) is closed towards the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d) or is hindered in carrying out gas exchange.

[0114] In the first diagram 21, the measured signal pattern 38″ shows a pattern that belongs to a sensor-measuring arrangement with a catalytic gas sensor 301 or to an electrochemical gas sensor 302, a decaying measured signal S 35, which both a catalytic gas sensor 301 and an electrochemical gas sensor 302 have a measured gas consumption. As a result, the measured signal S 35 decays after dispensing even if no gas can escape from the gas sensor 30 (FIGS. 1a, 1b, 1c and 1d) into the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d). The pattern according to 38″ thus shows, just as the pattern according to 38′″, a case in which the gas admission element 8 (FIGS. 1a, 1b, ac and 1d) is closed towards the measuring environment 2 (FIGS. 1a, 1b, ac and 1d) or is hindered in carrying out gas exchange. By comparing a signal level of at least one measured signal A′, A″, A′″ located in time after the maximum A.sub.Max in the signal pattern 38, 38′, 38″ with the maximum A.sub.Max, the control unit 3 (FIGS. 1a, 1b, 1c and 1d) determines whether the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d) is closed towards the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d) or is hindered in carrying out gas exchange. The comparison may be carried out, for example and preferably, by forming a weighted or unweighted ratio (quotient, percentage ratio) of the at least one measured signal A′, A″, A″ located in time after the maximum A.sub.Max in the measured signal pattern 38, 38′, 38″ to the maximum or by forming a difference between the at least one measured signal A′, A″, A′″ with the maximum A.sub.Max by means of the control unit 3 (FIGS. 1a, 1b, 1c, ad). In the view according to this FIG. 2, the measured signal A′ corresponds to a state of the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d) with an unhindered outflow and inflow from and to the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d). In the view according to this FIG. 2, the measured signal A″ corresponds to a state of the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d) with prevented outflow and/or inflow from/to the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d) in case of a catalytic gas sensor 301 (FIG. 1b) or of an electrochemical gas sensor 302 (FIG. 1c). In the view according to this FIG. 2, the measured signal A′″ corresponds to a state of the gas admission element 8 (FIGS. 1a, 1b, 1c and 1d) with prevented outflow and/or inflow from/to the measuring environment 2 (FIGS. 1a, 1b, 1c and 1d) in case of an optical gas sensor 300 (FIG. 1).

[0115] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

APPENDIX

LIST OF REFERENCE DESIGNATIONS

[0116] 1, 1′, 1″, 1′″ Gas-measuring arrangement, gas-measuring device [0117] 2 Measuring environment [0118] 3 Control unit, electronic unit [0119] 5 Quantity of test substance (liquid), injected [0120] 6 Quantity of test substance (gaseous), evaporated [0121] 7 Gas supply [0122] 8 Gas admission element, diaphragm, protective grid, flame protection [0123] 9 Test gas dispensing unit [0124] 21 First diagram [0125] 22 Second diagram [0126] 30 Gas sensor system [0127] 32 Memory (RAM, ROM) [0128] 33 Control line [0129] 35 Measured signal S, measured signal line [0130] 36 Signal transmission unit [0131] 38 Measured signal pattern [0132] 37 Signal supply unit [0133] 40 Acoustic alarm generator (horn) [0134] 44 Timer/stop watch/chronometer [0135] 50 Optical alarm generator (lamp) [0136] 60 Operating and display unit (user interface) [0137] 61 Screen element [0138] 70 Analysis system [0139] 71 Data bank [0140] 80 Output unit [0141] 81 Interface [0142] 91, 91′, 91″ Control signal, control signal pattern, control line [0143] 92 Signal and data line [0144] 300 Optical gas sensor, IR multireflection cell [0145] 301 Catalytic gas sensor, heat tone sensor [0146] 302 Electrochemical gas sensor [0147] 303 Semiconductor gas sensor [0148] 304 Valve [0149] 305 Test substance reserve, tank, container, cylinder [0150] 306 Reserve quantity [0151] 400 x axis, time course t [0152] 401 Time t.sub.1, activation time [0153] 402 Time t.sub.2, deactivation time [0154] 410 Time t.sub.0