Method and device for detecting a gaseous emission from a surface

Abstract

The invention relates to a device and a method for detecting a gaseous emission from a surface (4). According to the invention, at least one gas sensor arrangement (16) is included for detecting at least one gaseous substance emitted from a filmy residue (2) on the surface (4) of a solid or the surface (4) of a fluid (30).

Description

[0001] The invention relates to a method and a device for detecting a gaseous emission from a surface.

[0002] The processing aids used in the manufacture of technical components or assemblies (such as cooling lubricants, oils, greases, blasting abrasives, preservatives, and corrosion inhibitors) remain on the surface of the parts and assemblies and can reduce quality or lead to defective products in subsequent process steps (e.g., painting, bonding, coating, joining). To remove these processing aids, cleaning processes are sometimes carried out between individual manufacturing processes.Due to fluctuating process variables in the cleaning processes (increasing contamination, decreasing cleaning agent concentration) or fluctuating contamination levels of the parts (more adherent dirt or thicker residue layers), achieving the required component cleanliness while simultaneously maintaining efficient process control (long cleaning bath life, low temperatures, short cleaning times) cannot always be guaranteed. Therefore, the achievement of sufficient cleanliness for the subsequent process must be monitored.

[0003] Contamination on components is divided into particulate contamination (chips, abrasion debris) and filmy residues or contamination, as different substances can interfere with the performance of different applications. Let's take the production of an automotive oil pan as an example. Remaining drawing oil from production is not a problem, but metallic particles can damage the transmission.

[0004] Since cleaning processes always involve dilution series in which the contamination or the corresponding substance is diluted to a tolerable level, perfect cleanliness of the parts and surfaces is impossible to achieve. Small amounts of contamination will always remain on the surface. The necessary or sufficient cleanliness, i.e., how much contamination may remain on the surface, is defined by the requirements of the subsequent process. For example, solvent-based painting processes are significantly more robust against contamination on the parts because the solvent contained in the paint removes it, allowing the paint to adhere directly to the part surface.

[0005] In contrast, water-based paints are much more sensitive to dirty surfaces.

[0006] In another area of ​​application - the cleaning of machines and systems as well as entire production areas - the demand for solutions that localize and characterize contamination is very high.

[0007] From the document EP 3 950 159 A1, a sensor device for a cleaning system, comprising a contamination sensor and a light source, is known. According to paragraphs

[0011] to

[0013] , the contamination sensor is designed in particular as an optical sensor, for example a camera, and scans the surroundings for contaminated areas. The function of this optical sensor is preferably based on a luminescence effect. A light spectrum is emitted that produces an easily detectable luminescence effect in the presence of the expected contamination (e.g., bacterial growth). Alternatively, it is also possible to apply an agent to the surface to be tested that, in conjunction with the contamination to be removed, produces a luminescence effect under the intended lighting.The wavelength of the light radiation emitted by the cleaning device or in the application space may, for example, lie outside the visible spectrum and at least partially comprise the UV or IR spectrum.

[0008] Due to the lack of selectivity of the method, particulate and film-like contamination often cannot be distinguished. Furthermore, fluctuations in ambient light can distort the measurement signal. Furthermore, the method relies on the fluorescence reaction of the contaminants (silicone oils, for example, do not fluoresce). Determining the contamination thickness or component cleanliness is not possible with varying contamination levels, as different materials fluoresce to varying degrees. If the component to be inspected for contamination is made of a fluorescent material (e.g., plastic, electrical circuit boards), the contamination cannot be detected.

[0009] The surface tension of a surface indicates how well it is wettable. The formation of a water droplet on a hydrophobic surface (low surface tension), where it forms a sphere, is well known. On a hydrophilic surface (high surface tension), on the other hand, the water droplet spreads out. Since the surface tension of filmy residues (oils, greases, etc.) differs greatly from that of the material of the part (metals, for example, have a high surface tension), even very thin films can cause large changes in the measurable surface tension. However, since residues from cleaning processes (e.g. surfactants such as soap) on the surface also ensure good wettability, the measurement of good wettability (high surface tension) does not always mean that the surface is clean. In addition, dried-on filmy residues orContamination layers caused by processes such as plasma activation can exhibit high surface tensions, yet still interfere with the subsequent process (e.g., a paint layer peels off because it only adheres well to the contamination, but not to the actual part). Furthermore, surface tension measurement cannot distinguish between different types of contamination.

[0010] As a result, cleaning is at best carried out with excessive effort, and the cleaning baths are only partially utilized, as they are replaced prematurely or used at higher temperatures and / or with higher cleaning agent concentrations. The resulting increase in resource consumption during production increases production costs and pollutes the environment. If inadequately cleaned parts are not detected, late failures can result in high follow-up costs for the end customer, not least for the manufacturer. In hygiene-critical areas, the consequences can be even more dramatic (keyword: "food safety").

[0011] It is therefore an object of the invention to provide a simple and safe method for detecting a gaseous emission from a surface and the device to be used for this purpose in order to draw conclusions from the gaseous emission about a filmy residue, such as an impurity or contamination, on a surface or about the condition of a fluid, in particular a washing, cleaning or solvent fluid, about residues or contamination introduced therein, i.e. dissolved or dispersed, or about missing or reduced contents of additives due to consumption.

[0012] This object is achieved by a device for detecting a gaseous emission from a surface. According to the invention, at least one gas sensor arrangement is included for detecting at least one gaseous substance emitted from a filmy residue on the surface, which represents a solid surface, or the surface of a fluid, which represents a fluid surface. Preferably, an evaluation device connected at least to the gas sensor arrangement for transmitting sensor data is also provided. The detection of the gaseous substance allows conclusions to be drawn about the presence or type of the filmy residue, for example, a contamination.

[0013] If the surface is that of a washing, cleaning, or solvent fluid, the detection of the gaseous substance can be used to determine the presence of dissolved or dispersed residues and thus the degree of contamination of the fluid. In addition to this effect, the content of certain additives in the fluid can also be monitored, and the consumption of a washing, cleaning, or solvent fluid can be determined based on the lack or reduced content of additives. This can be done by detecting the gaseous substance above the surface.

[0014] It has proven advantageous if the at least one gas sensor arrangement is designed as a sensor for monitoring an area above the surface to determine the presence of a specific gaseous substance, such as carbon dioxide (CO2) or hydrogen (H2). The air in the area above the surface can be monitored above a component or above a fluid. Alternatively, a combination of several different sensors, in particular sensors for low-molecular to high-molecular substances, is provided, which are arranged directly above the surface or at a distance from the surface.

[0015] When monitoring the area above the surface by analyzing the air there, the emission can originate from any location. While spatial assignment is not possible or hardly possible, the distance of the sensor arrangement from the surface allows a large surface to be easily monitored. This is particularly sufficient for a fluid that has a substantially uniform concentration and thus outgassing across the entire surface. The air in the head area of ​​a cleaning bath tank can be monitored.

[0016] By deliberately arranging multiple sensors, intensity monitoring, a combination of sensor signals from multiple gas sensor arrays, or multiple sensors combined into a single gas sensor array, which also determines the existing intensity of the gaseous substance, can be used to locate the odor source, i.e., the location of the emission, and thus determine the location of the contamination. In addition, air flow in the measurement area can also be taken into account and used as a corrective when determining the location of the emission.

[0017] According to a preferred embodiment, an activation device is included for activating the residue and for increasing the emission of the at least one gaseous substance. According to a first alternative, the activation device is designed as a heating device for at least locally heating the surface. It has proven advantageous if the heating device is designed to emit infrared radiation, microwave radiation, UV radiation, and / or to generate an electrical charge.

[0018] According to a second alternative, the activation device is designed for a mechanical action. If the residue is a solid film, the activation device applies frictional forces to the residue, thereby generating increased emission of the gaseous substance to be detected, for example, by disrupting the cohesion of the already outgassed surface or by disrupting a crust formed on the residue. The crust is scratched by the frictional forces, allowing the gaseous substance to escape unhindered from the underlying layers. Mechanical activation can also be achieved by a device that generates ultrasound and acts on the film. The ultrasound is usually transmitted from the ultrasound source to the film via a fluid.In addition, the fluid whose surface is to be monitored can be subjected to ultrasound in order to achieve an increased release of the gases to be detected.

[0019] If the detection of the gaseous substance is to occur above the surface of a fluid, the activation device applies shear forces to the fluid, mixes the fluid layers, and promotes the outgassing of dissolved substances across the surface. Such an activation device is designed, for example, as a stirrer. When the fluid is stirred, gases escape more rapidly and can be detected more easily, quickly, and accurately at the surface or in the airspace above the surface, or with a simpler, less sensitive gas sensor arrangement.

[0020] A further advantageous embodiment comprises a suction device for sucking air from the surface or the area above the surface, for example the air space above the surface. This serves for sampling by sucking out the air containing the gas to be detected, the gaseous substance, above the sampled surface and feeding it as a sample for analysis. A preferred embodiment with a suction device comprises an air guiding device, such as a nozzle, so that the air flow is directed specifically from a narrowly defined area of ​​the surface to the at least one gas sensor arrangement and only the gaseous substances emitted from a limited area are detected. This allows a more precise, spatially resolved image of the contamination to be obtained and a subsequent cleaning process to be carried out more precisely.The extraction system can also be used to direct air into the gas sensor array in a targeted manner, thus easily increasing the sensitivity of the detection. The air guiding system is designed accordingly for this purpose, with various options available to the specialist, from which they can select according to their expertise.

[0021] A further advantageous embodiment comprises at least one surface condition sensor for determining further parameters and state variables of the surface, e.g., material, roughness, temperature. Temperature, in particular, significantly influences the outgassing from the filmy residue and is therefore preferably also recorded. By determining further parameters and state variables of the surface, at least the composition and properties of different filmy residues can be differentiated and, in particular, the fact that certain parameters and state variables influence, on the one hand, the type and extent of contamination and, on the other hand, the necessary cleaning processes can be taken into account. If the surface is that of a fluid, other parameters and state variables can be considered for additional recording, in particular rheological properties.

[0022] Furthermore, it has been shown that advantages arise when at least one air condition sensor is included for determining additional properties of the air surrounding the surface, e.g., temperature, humidity, and / or pressure. The properties of the air primarily influence the release of the gases to be detected from the filmy residue, as well as the interaction with the air in the time between release and analysis, which can influence the analysis result. These interactions and influences are preferably considered when evaluating the sensor data from all sensors used in an evaluation device.

[0023] A device for concentrating the emitted gaseous substance has proven particularly advantageous, allowing more precise results for subsequent analysis using the gas sensor array and increased sensitivity. This allows low concentrations that would otherwise be undetectable or only detectable with increased effort to be detected at all, or with less effort, e.g., using a simpler gas sensor array. Concentration can be achieved simply by blowing air extracted from the surface onto the gas sensor array. Various other options are available to the expert, from which they can select according to their expertise.

[0024] In addition to recording the properties of the surface and the surrounding air, the determination of additional parameters has proven advantageous. Therefore, at least one device is preferably provided for recording mechanical properties of the component to which the surface belongs, e.g., geometry, size, and shape. If the surface is that of the fluid, typical properties of a fluid, particularly rheological properties, can be considered instead of fixed state variables. In both cases, the accuracy of determining the composition of the filmy residue, in particular the state of cleanliness, or of the fluid, in this case its contamination or the consumption of ingredients necessary for successful cleaning, can be increased.

[0025] According to various alternative embodiments, the device is designed as a laboratory measuring device for stationary testing, as a handheld measuring device for mobile testing, or permanently installed in a production line for inline measurement, where connection to automation technology also offers particular advantages. Samples are usually fed to the laboratory measuring device and the corresponding gas analyses are carried out in the laboratory. The handheld measuring device for mobile testing is brought to the surface to be tested in order to carry out the desired analyses there. This can be done, for example, to determine the cleaning requirement or the cleaning success in a system. For inline measurement, the measuring technology is permanently installed so that parts moving past can be tested. Such use is conceivable, for example, between different production stages that require intermediate cleaning.In practical use, such a measuring system can be mounted passively on the production line (i.e., between cleaning and the next production step). The passing parts influence the measurement signal, leading to the desired measurement result.

[0026] Particularly in handheld devices for mobile testing, it has proven advantageous if the gas sensor arrangement is designed to detect different signal strengths, for example, by detecting different signal strengths and signaling and / or evaluating them accordingly. Signal strength analysis of the sensor signal can be used to locate contamination.

[0027] When used as a handheld measuring device, the user can locate contamination sources and biofilms by using the signal strength to indicate the direction in which the contamination source is likely to be located. When swiveling and moving the handheld measuring device, preferably parallel to the surface, the contamination source is likely to be located in the direction in which the signal strength increases. When moving linearly in space, the signal becomes stronger the closer the distance to the contamination source.

[0028] According to an advantageous embodiment, three gas sensor devices are arranged at a distance from one another in such a way that the measured values ​​of at least three of the gas sensor devices can be used to determine the position of the emission source using the principle of triangulation. Triangulation is a geometric method of optical distance measurement by precisely measuring angles within triangles. The calculation is performed using trigonometric functions. This makes it possible to perform angle measurements from two points whose distance is known to any other point in space in order to unambiguously identify their position. If three points are known, no angle measurements are necessary.

[0029] The object of the invention is also achieved by a method for detecting a gaseous emission from a surface, a gaseous substance emitted from a filmy residue on the surface of a solid or the surface of a fluid, with the aim of determining the filmy residue on the solid surface or the state of the fluid beneath the surface. According to the invention, at least one gaseous substance emitted from the layer of residue is detected if it is a layer on a solid, in particular a component or the surface of a system. If, however, the emission occurs from the surface of a fluid, its constituents, at least qualitatively relevant portions, are quantitatively determined. The relevant portions of the fluid can, on the one hand, be introduced substances, e.g., substances detached during cleaning processes and introduced into the fluid.On the other hand, the proposed method can be used to determine whether essential components of the fluid, e.g., additives in a cleaning bath, are present in sufficient concentration or have already been consumed.

[0030] In addition, after detection by the gas sensor array and all other sensors, the sensor data is preferably transmitted to an evaluation device for appropriate analysis. The evaluation result can be displayed locally or transmitted for display. However, the analysis result can also be processed in an evaluation or control device and trigger automated actions, such as changing the cleaning procedure or removing parts for re-cleaning.

[0031] According to an advantageous embodiment of the method, monitoring of the quality of the room air and / or at least one specific gaseous substance such as CO2 or H2 is provided. Preferably, air or the gas present there is sucked off the surface for sampling. This embodiment of the method is particularly advantageous where the aim is to monitor a fluid and the emission of gaseous substances via the surface of the fluid. Here, the room air can be monitored in a headspace of a container containing the fluid, for example a cleaning fluid. In both cases, the monitoring can alternatively or additionally be limited to the extent that at least one specific gaseous substance is detected.

[0032] If only specific areas of a component are to be checked for cleanliness (e.g., functional surfaces for bonding), means can be used to specifically vacuum these areas. Vacuuming is therefore advantageously carried out via an air guiding device, such as a nozzle or adapter, so that the air flow is directed specifically to the at least one gas sensor arrangement and only the gaseous substances emitted from a limited area are detected.

[0033] Suction can also be performed above the surface of a fluid. In this case, the advantages are that the emitted substances can be absorbed with minimal loss. Targeted suction prevents, for example, gaseous substances from being blown away, which would then reach the gas sensor array in reduced concentrations.

[0034] Activating the surface to increase the emission of the at least one gaseous substance, making it easier to detect, has also proven advantageous. According to a first alternative, the activation occurs by at least local heating of the surface and the residue deposited thereon. Infrared radiation, microwave radiation, UV radiation, and / or electrical charging are provided for heating purposes.

[0035] According to a second alternative, the activation of the surface and / or the residue occurs through mechanical influence. If it is a fluid, the mechanical influence consists of introducing shear forces into the fluid below the surface. In particular, the fluid is stirred, thus forcing the outgassing of constituents.

[0036] With a solid surface, frictional forces are introduced into the residue, which subsequently releases gaseous substances more easily or in greater quantities, which can then be detected more easily. Additionally, it has proven advantageous to extract air from the surface for sampling, ensuring that the emitted gases are fed to the gas sensor array without loss.

[0037] Ultrasound is also planned for mechanical activation. This can be used both to activate the solid surface and / or the residue, as well as to activate a fluid, thus forcing the outgassing of ingredients.

[0038] Furthermore, it has been shown that at least one determination of further parameters and state variables of the solid surface, e.g., material, roughness, temperature, or rheological properties of the fluid, is advantageous, so that at least the composition and properties of various filmy residues and their formation, or different fluids, can be distinguished. In addition, at least one further property of the air surrounding the surface, e.g., temperature, humidity, pressure, is preferably recorded.

[0039] A further advantageous embodiment of the method consists in concentrating the emitted gaseous substances before supplying the air containing the substances to the sensor in order to achieve a higher sensitivity of the analysis.

[0040] To further increase the accuracy of the method according to the invention, at least one mechanical property of the component to which the surface belongs, e.g., geometry, size, shape, is recorded. This can increase the accuracy of determining the cleanliness level.

[0041] If either different methods within the meaning of the invention or the same method with different intensities (e.g., with a different amplitude or power) are used to extract the detectable components, the composition, thickness, or other properties characterizing the filmy residue can also be detected, providing detailed information about the condition of the surface in question. The same applies to mechanical properties of the fluid, such as its rheological properties.

[0042] By adding specific additives or specifically selecting the composition of the processing aids already used, the detectability of the filmy residue that subsequently remains on the parts can be specifically enabled or improved, even with initially non-odorous substances that produce too few detectable emissions. This is achieved, in particular, by adding highly volatile substances that are easily detectable by the gas sensor array.

[0043] When assessing the hygiene status of production environments, the sensor system or the device according to the invention can be used to localize contamination by measuring a gradient, in particular the increase in the signal (comparable to the use of a metal detector), but can also be used to determine the amount and type of contamination (e.g., to detect biofilms). Therefore, the increase in the signal is preferably measured along the path in order to be able to specifically localize contamination on the surface during movement.

[0044] In an alternative embodiment of the invention, the gas sensor array is mounted in the air-filled head region of the cleaning bath container, since the concentration of volatile compounds that indicate contamination is particularly high here. Specifically, a gas sensor array for fluids, particularly wash baths, detects the reduction in additives and the contamination in the wash bath. In this case, an air exchange, i.e., filling the air reservoir with fresh air, followed by an integral measurement, is advantageous before starting the measurement.

[0045] The cleaning fluid used is reused in many industries. This can lead to the carryover of contaminants, which is why the degree of contamination in the cleaning bath itself has a significant impact on the achievable cleanliness of the parts to be cleaned. Suitable or cost-effective technologies for determining the degree of contamination are currently lacking. In addition, the reduced use of chemicals leads to increased growth of microorganisms in the cleaning baths, which represents a further source of contamination and can pose a hazard to operators and production. Therefore, additional monitoring of the cleaning bath is required.

[0046] The advantages of the present invention lie not least in the fact that gas sensors, indoor air sensors, and indoor climate sensors are widely available and inexpensive. If one or more of these sensors are used in the system according to the invention, the complete solution can also be implemented more cost-effectively than prior art solutions.

[0047] The excellent inline capability of the inventive measuring method (for use in the production chain) enables cost-effective and comprehensive part inspection, helping to avoid scrap and manage processes efficiently. This is achieved, for example, by avoiding premature replacement of cleaning baths.

[0048] In contrast to surface tension measurement, this method is contactless and interference-free, meaning it does not affect the surfaces being examined. Thus, there is a low risk of contamination from the sensor.

[0049] In fluorescence measurement technology, non-fluorescent contaminants are often mixed with fluorescent dyes (tracers). However, these are very expensive compared to the processing aid and represent an additional source of error and a contaminant for downstream processes. In the method according to the invention, however, good detectability can be ensured by carefully selecting the substance with the strongest odor. Alternatively, highly volatile additives that do not affect downstream processes are possible.

[0050] A technical application of the invention can be advantageous in the following areas: 1. Component manufacturing (mechanical or electrical parts and assemblies): In manufacturing processes where a substance intentionally or unintentionally comes into contact with the parts during the process, this substance later acts as an impurity in a subsequent process (e.g. bonding, painting, joining, sealing) and must be efficiently removed in an intermediate cleaning process. 2. Medical technology: The filmy residues promote the growth of germs or directly contamination of the patient or their environment. 3. Semiconductor industry: The filmy residues that remain on the components, transport equipment or tools used in semiconductor manufacturing evaporate into the cleanroom and contaminate the cleanroom. 4. Food production: Cleaning of plant equipment to improve hygiene (preventing or limiting germ growth) and safety while effectively using resources for cleaning. 5. Bioprocess engineering: see section 4. 6. Pharmaceutical industry: see point 4.

[0051] The invention is explained in more detail below with reference to the description of embodiments and their representation in the accompanying drawings. Fig. 1 schematically shows a view of an embodiment of a device 1 according to the invention and a film residue 2 on a surface 4 of a component 6.

[0052] The device 1 comprises a suction device 10, which sucks a gaseous substance released from the filmy residue 2 from the surface 4. The suction device 10 comprises a suction pump 14, which generates an air flow 15 in an air tube 13. The air tube 13 extends to the surface 4 with an air guiding device, designed as a nozzle 12. The air sucked from the surface 4, the air flow 15, passes through a gas sensor arrangement 16, which determines the components of the sucked-off gaseous substance or their presence, and exits the air tube 13 via an air outlet 18.

[0053] An activation device, designed as a heating device 8, is used to activate the film residue 2 with the aim of releasing a larger amount of the gaseous substance. The heating device 8 radiates heat onto the film residue 2, with the heat radiation represented by short straight lines, whereupon the film residue 2 heats up. The heated film residue 2, in turn, radiates heat back, represented by short double wavy lines, and simultaneously releases a larger amount of the gaseous substance compared to the non-activated state.

[0054] Further measured values ​​are determined by an air condition sensor 22, which determines the properties of the ambient air surrounding the component 6. In addition, a surface condition sensor 20 generates measured values; in particular, mechanical condition values ​​of the surface 4 and / or the component 6 are determined. The sensor data from the gas sensor arrangement 16, the surface condition sensor 20, and the air condition sensor 22 are transmitted to an evaluation device 24, which can be done via cables (not shown) or wirelessly. In the evaluation device 24, the results from the gas sensor arrangement 16 are related to the other measured values ​​contributed by the surface condition sensor 20 and the air condition sensor 22. As a result, process parameters for a cleaning process, in particular, can be derived.

[0055] Fig. Figure 2 shows schematically a view of an embodiment of a device 1 according to the invention corresponding Fig. 1, but here over a surface 4 of a fluid 30. Compared to the Fig. The device 1 shown in Figure 1 includes a device 32 for concentrating the gaseous substances drawn in via the air guide device 12. Their emission over the surface 4 of the fluid 30 is forced by a stirrer 34, which serves as a device for mechanically influencing the fluid and applying shear forces there. List of reference symbols 1 device 2 film residue 4 Surface 6 Component 8 Activation device, heating device 10 Extraction device 12 Air guiding device, nozzle 13 Air pipe 14 Suction pump 15 Airflow 16 Gas sensor arrangement 18 Air outlet 20 Surface condition sensor 22 Air condition sensor 24 Evaluation device 30 Fluid 32 Concentration facility 34 Device for mechanical influence, stirrer QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 950 159 A1

[0007]

Claims

[1] Device for detecting a gaseous emission from a surface (4), characterized by , that at least one gas sensor arrangement (16) is included for detecting at least one gaseous substance emitted from a filmic residue (2) on the surface (4) of a solid or the surface (4) of a fluid (30). [2] Device according to claim 1, wherein the at least one gas sensor arrangement (16) is designed to detect the presence of a specific gaseous substance in an area above the surface (4) or as a combination of several different sensors. [3] Device according to claim 1 or 2, wherein an activation device (8) for activating the residue (2) or fluid (30) is included, wherein the activation device (8) contributes to the increased emission of the at least one gaseous substance. [4] Device according to claim 3, wherein the activation device (8) is designed as a heating device for at least local heating or as a device for mechanically influencing the surface (4) and / or the residue (2). [5] Device according to claim 4, wherein the heating device is designed to emit infrared radiation, ultrasound, microwave radiation, UV radiation and / or to generate an electrical charge. [6] Device according to claim 4 or 5, wherein the device for mechanical influence is designed to introduce shear forces into the fluid (30) below the surface (4) or to introduce frictional forces into the residue (2) or as a device for generating ultrasound. [7] Device according to one of the preceding claims, wherein a suction device (10) for suctioning air from the surface (4) is included for sampling. [8] Device according to claim 7, wherein the extraction device (10) comprises an air guidance device (12) which, according to a first embodiment, is designed such that an airflow (15) is directed from a limited area of ​​the surface (4) to the at least one gas sensor device (16) and only the gaseous substances emitted from the limited area are detected and / or, according to a second embodiment, is designed such that the gas sensor arrangement (16) is directed to be blown on. [9] Device according to one of the preceding claims, wherein at least one air condition sensor (22) is included for determining further properties of the air surrounding the surface (4). [10] Device according to one of the preceding claims, comprising a device for concentrating (32) the emitted gaseous substance. [11] Device according to one of the preceding claims, comprising at least one device for detecting mechanical properties of the component (6) or of the fluid (30) to which the surface (4) belongs. [12] Device according to one of the preceding claims, designed as a laboratory measuring device for stationary testing, as a handheld measuring device for mobile testing or for inline measurement in a production line with connection to an automation technology. [13] Device according to one of the preceding claims, wherein the gas sensor arrangement (16) is designed to determine different signal strengths, so that localization of contaminants can be carried out by evaluating the signal strength of the sensor signal. [14] Device according to one of the preceding claims, wherein at least three gas sensor devices (16) are spaced apart from each other in such a way that the position of the emission source can be determined from their measured values. [15] Method for detecting a gaseous emission from a surface (4), characterized by , that at least one gaseous substance emitted from a filmic residue (2) on the surface (4) of a solid or the surface (4) of a fluid (30) is detected. [16] Method according to claim 15, wherein monitoring of the quality of the room air and / or at least a specific gaseous substance is carried out. [17] Method according to claim 15 or 16, wherein the surface (4) is activated to increase the emission of the at least one gaseous substance. [18] Method according to claim 17, wherein the activation is carried out by at least local heating of the surface (4) or by mechanical influence on the surface (4) and / or the residue (2). [19] Method according to claim 18, wherein the heating is carried out by infrared rays, microwave radiation, UV radiation and / or an electrical charge. [20] Method according to claim 17 or 18, wherein the mechanical influence is effected by an introduction of shear forces into the fluid (30) below the surface (4) or by an introduction of frictional forces into the residue (2) or by the action of ultrasound. [21] Method according to any one of claims 15 to 20, wherein air is extracted from the surface (4) for sampling. [22] Method according to claim 21, wherein the extraction is carried out via an air guidance device (12) so that an airflow (15) is directed from a limited area of ​​the surface (4) to the at least one gas sensor arrangement (16) and only the gaseous substances emitted from the limited area are detected. [23] Method according to any one of claims 15 to 22, wherein at least one further property of the air surrounding the surface (4) is detected. [24] Method according to any one of claims 15 to 23, wherein the emitted gaseous substances are concentrated. [25] Method according to any one of claims 15 to 24, wherein at least one mechanical property of the component (6) to which the surface (4) belongs or of the fluid (30) is detected. [26] Method according to any one of claims 15 to 25, wherein the substance forming the filmic residue (2) is combined with additives or processing aids are defined to enable or improve the detectability of the filmic residue (2) subsequently remaining on the surface (4). [27] Method according to one of claims 15 to 26, wherein the filmic residue (2) on the surface (4) is localized by means of signal strength evaluation and / or by evaluation of measured values ​​from more than three spaced-apart gas sensor arrangements (16).

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