Analyzer with a chemical filter around the measuring chamber

Abstract

A gas analyser comprises a sensor 50 comprising a measuring chamber 30 which takes up a gas sample Gp and generates a signal which correlates with target gas concentration. A filter component 20 comp

Description

DESCRIPTION

[0001] The invention relates to an analyzer comprising a measuring chamber, a sensor on or in the measuring chamber, and a chemical filter around the measuring chamber.

[0002] The analyzer can measure the concentration of at least one target gas in a gas sample and can generate a signal that correlates with the measured target gas concentration, in other words, contains information about the measured target gas concentration. Different principles for the sensor of such an analyzer have become known. One principle makes use of the fact that a target gas absorbs electromagnetic radiation in a specific wavelength range. The electromagnetic radiation passes through a gas sample to be examined. A detector measures an indicator for the intensity of incident electromagnetic radiation. Another principle makes use of the following fact: Combustible target gas releases heat while it is heated and oxidized in the process. The heat released is an indicator for the target gas concentration. The invention can be used in combination with a sensor implemented in this way.

[0003] The object of the invention is to provide an analyzer which is able to measure the concentration of a predetermined target gas in a gas sample and which is less cross-sensitive than known analyzers to a substance that is or may be present in the gas sample.

[0004] The object is achieved by an analyzer having the features of claim 1. Advantageous embodiments of the analyzer according to the invention are specified in the dependent claims.

[0005] The analyzer according to the invention comprises a measuring chamber and a sensor. The measuring chamber is able to take-up (hold) a gas sample. The gas sample comes from a spatial region to be monitored and flows from there into the measuring chamber. The sensor is able (configured) to measure the concentration of the target gas in the gas sample and to generate a signal. The generated signal correlates with the measured concentration of the target gas in the gas sample, thus containing information about the measured target gas concentration, wherein the gas sample is located in the measuring chamber. It is possible that the sensor is able to measure the respective concentration of several target gases or the sum of several target gas concentrations. Preferably, the sensor is arranged in and / or on the measuring chamber.

[0006] Note: The formulation that a sensor is able to measure a physical variable means the following: The sensor measures directly the physical variable or at least one other variable that correlates with the sought physical variable and is therefore an indicator for the sought physical variable. The measurement provides at least one value for the physical variable. In the present case, the sensor measures a detection variable that correlates with the sought target gas concentration, in particular the electrical voltage or the electrical charge or another electrical detection variable.

[0007] The analyzer also comprises both a filter component comprising a chemical filter and a further component. The filter component and the further component collectively surround the measuring chamber, preferably entirely (in full). It is possible that the filter component and the further component each surround only a respective part of the measuring chamber. Preferably, however, the filter component surrounds the entire measuring chamber, and the further component also surrounds the entire measuring chamber.

[0008] Collectively, the filter component and the further component are intrinsically dimensionally stable (stable in shape). It is possible that both the filter component and the further component are intrinsically dimensionally stable. It is also possible that the filter component maintains the shape of the further component or, conversely, the further component maintains the shape of the filter component. Preferably, the filter component and the further component are fastened to a housing around the measuring chamber in such a way that, during use, neither the filter component nor the further component can move relative to a housing around the measuring chamber.

[0009] Note: A dimensionally stable component is understood to mean a component that retains its shape during use or at least returns to its original shape when it is compressed or stretched or otherwise deformed. The dimensionally stable component can therefore in particular be elastically deformable or rigid. A component made of metal or of a rigid plastic is dimensionally stable, a rag or a cloth is not dimensionally stable.

[0010] At least one filter opening is inserted (made) into the filter component. At least one component opening is inserted into the further component. Both the filter component and the further component are impermeable to gas with the exception of the respective at least one opening. Therefore, the gas sample from the spatial region to be monitored can only reach the interior of the measuring chamber via a path that passes through the or at least one component opening and through the or at least one filter opening. “Impermeable” means: Ideally, the two components are completely impermeable to gas so that a gas sample can only reach the measuring chamber through the component opening(s) and through the filter opening(s). In practice, the two components are impermeable only with the exception of the openings and unavoidable slots, gaps and / or other unavoidable recesses. As a rule, it is unavoidable, for example due to material inaccuracies and deformations caused by the ambient temperature, that a small portion of the gas sample flows past (circumvents) the or each opening and reaches the interior of the measuring chamber. As a rule, however, this does not lead to a false measurement result. [0011 ] The chemical filter is a component of the filter component. It is possible that the entire filter component functions as the chemical filter.

[0012] A gap (slit) occurs between the filter component and the further component, preferably a circumferential gap. The or each filter opening and the or at least one component opening are arranged as follows: A gas sample flowing from the outside, i.e., from the spatial region, and entering the interior of the measuring chamber is forced on a path through the gap or through a part of the gap and passing the chemical filter on the way through the gap. The gas sample thus flows past (along) the chemical filter before reaching the measuring chamber. No relevant portion of the gas sample can bypass the chemical filter and then enter the measuring chamber.

[0013] The path, which the gas sample is forced to take before reaching the interior of the measuring chamber, comprises a section. This section lies in the gap and has a length of at least 0.5 cm, preferably a length of at least 1 cm or 2 cm, particularly preferably a length of at least 5 cm, in particular a length of at least 10 cm. At least along this section, the gas sample flows past (along) the chemical filter before reaching the measuring chamber.

[0014] The chemical filter is able to achieve the following effect: The chemical filter binds at least one chemical substance that is or at least may be present in the gas sample, or breaks down this chemical substance, or converts the chemical substance. For example, a gaseous substance in the gas sample is chemically converted into a solid substance. The chemical filter achieves this effect while the gas sample flows through the gap and past the chemical filter. Ideally, by interacting in the manner just described, the filter component comprising the chemical filter and the further component prevent a relevant quantity of the chemical substance as a component of the gas sample from reaching the interior of the measuring chamber.

[0015] According to the invention, the or at least one predetermined chemical substance is prevented from entering the interior of the measuring chamber. “Predetermined” means: This substance occurs or at least may occur in the spatial region to be monitored and therefore also in the gas sample. This substance is known in advance. It is often undesirable for at least one predetermined substance to enter the interior of the measuring chamber as part of a gas sample. For example, the substance could damage a component inside the measuring chamber or render it inoperative. It is also possible that the substance distorts or at least may distort a measurement result of the analyzer.

[0016] It would be conceivable to arrange a filter around the measuring chamber, wherein this filter is implemented as a flow-through filter. The gas sample flows through pores in this flow-through filter and into the interior of the measuring chamber, and the flow-through filter filters the substance out of the gas sample flowing therethrough or otherwise prevents the substance from reaching the interior of the measuring chamber.

[0017] In particular, the conceivable design comprising the flow-through filter has the following disadvantage: As a rule, a flow-through filter has a higher pneumatic flow resistance than the chemical filter on the filter component and a higher pneumatic flow resistance than the further component of the analyzer according to the invention. In particular for this reason, it usually requires more time for the gas sample to flow through the flow-through filter and reach the interior of the measuring chamber. Therefore, an analyzer comprising a flow-through filter is only able to detect the target gas or a target gas after a greater amount of time, compared to an analyzer according to the invention.

[0018] In particular, the shorter response time in comparison to a flow-through filter is achieved by the gas sample passing through the component opening(s) and the filter opening(s) into the interior of the measuring chamber but not through pores in a flow-through filter. How quickly a gas sample reaches the interior of the measuring chamber can be influenced by different design parameters of the analyzer according to the invention, in particular by the thickness (width) and optionally the geometry of the gap between the filter component and the further component and by the arrangement and dimensions of the openings.

[0019] In many cases, the analyzer according to the invention also achieves the following advantages, in particular in comparison to an analyzer comprising a flow-through filter: The gas sample flows through the gap (slit) between the filter component and the further component before reaching the measuring chamber. The path taken by the gas sample through the gap before reaching the measuring chamber has a section of at least 0.5 cm, preferably at least 2 cm in length. If there is a plurality of openings in the filter component and / or in the further component, it is possible that a portion of the gas sample flows over a first section of at least 0.5 cm in length and another portion of the gas sample flows over a second section of at least 0.5 cm in length.

[0020] In many cases, this makes the following possible: In comparison to a flow-through filter, a significantly longer section can be provided, namely the section of at least 0.5 cm in length. As the gas sample flows into the measuring chamber, it flows past the chemical filter along this section. Along this section, the chemical filter on or in the filter component is able to bind or break down the substance or convert it into a solid substance. This reduces the risk of a relevant quantity of the substance reaching the interior of the measuring chamber. If, however, a flow-through filter was used, a portion of the gas sample could flow through a pore in the flow-through filter and optionally through an opening overlapping the pore and into the interior of the measuring chamber without being forced past the chemical filter along a path through a gap.

[0021] In addition, in some cases, the invention reduces the risk that the chemical filter or another component will become clogged, and the gas sample will no longer be able to reach the measuring chamber. This undesirable effect often occurs with a flow-through filter because the pores become smaller and smaller over the course of use and eventually close completely. In particular, this effect often occurs because the flow-through filter binds a substance to be filtered out and the bound substance therefore reduces the pores or, more precisely, the area available for the gas sample to flow through.

[0022] Another disadvantage of a flow-through filter occurs if at least one chemical component of the filter is hygroscopic and absorbs ambient humidity. Examples of such chemical components are inorganic salts and compounds that chemically bind the substance to be filtered out. Since the chemical component is hygroscopic and absorbs ambient humidity, the flow-through filter swells. This also causes the pores to become smaller and smaller. In addition, the pneumatic resistance of the flow-through filter increases. One consequence is: A flow-through filter can often only be used when the ambient humidity is relatively low. The analyzer according to the invention does not have this disadvantage and can therefore often also be used in environments with relatively high ambient humidity.

[0023] According to the invention, a gas sample is forced onto a path through the gap on its way from the spatial region to be monitored into the measuring chamber. This path comprises a section that is at least 0.5 cm long, preferably at least 2 cm long. In one embodiment, the filter component, the further component, and the gap extend along a common longitudinal axis or along a plurality of parallel longitudinal axes. The filter component, the further component, and the openings are arranged in such a way that the following effect is achieved: The section of at least 0.5 cm in length extends in parallel with these parallel longitudinal axes. In another embodiment, the filter component extends in one plane. The section that is at least 2 cm length is arranged in parallel with this plane. In one embodiment, this plane is perpendicular to a longitudinal axis of the filter component.

[0024] According to the invention, the filter component comprises at least one filter opening. The further component comprises at least one component opening. On its way into the measuring chamber, the gas sample flows through the or a component opening and through the or a filter opening. Preferably, the or at least one filter opening, preferably each filter opening, has a minimum dimension of at least 0.5 cm, preferably of at least 1 cm, particularly preferably of at least 2 cm, in a plane perpendicular to the flow direction. The or at least one, preferably each, component opening also has a minimum dimension of at least 0.5 cm, preferably of at least 2 cm, particularly preferably of at least 5 cm, in a plane perpendicular to the flow direction.

[0025] In comparison to smaller openings, this embodiment further reduces the risk of an opening becoming clogged with particles, with these particles flowing through the opening as part of the gas sample and settling at the opening. This event is undesirable because the opening can become clogged, and a gas sample can then only flow into the measuring chamber with a lower volume flow or even not at all. In addition, the advantageous embodiment often results in a larger volume flow of the gas sample being achievable and the gas sample therefore reaching the measuring chamber more quickly. This in turn reduces the response time of the analyzer. A target gas can be detected more quickly.

[0026] According to the invention, the filter component and the further component collectively, preferably each one individually, form a dimensionally stable component which surrounds the measuring chamber, preferably in full. The dimensional stability reduces the risk of a part of the filter component or of the further component getting into the measuring chamber. This is undesirable, for example, if the sensor is implemented as a photoelectric sensor and no part is to enter the optical path between a radiation source and a detector. This is also undesirable if the sensor is implemented as an electrochemical sensor and no part is to come into contact with an electrode of the electrochemical sensor. Neither the filter component nor the further component is to come into contact with a heated component of the sensor, which is usually prevented by the dimensional stability. The risk that a part of the filter component and thus possibly a part of the chemical filter entering the interior of the measuring chamber would be greater if the chemical filter were constructed, for example, as a rag or cloth and were not held in a certain position by a dimensionally stable component.

[0027] It is possible that the filter component surrounds the further component. Preferably, however, the further component surrounds the filter component, preferably in full. In many cases this design makes it possible for a user to be able to replace the filter component and thus the chemical filter without directly touching the chemical filter, in particular if the filter component is rigidly connected to the further component. Such contact may have undesirable effects on a user's skin and / or may adversely affect the chemical filter. The design makes it possible to prevent these undesirable consequences without the user necessarily having to wear suitable protective equipment, such as gloves. In this application, the further component around the filter component thus functions as a handling protection means.

[0028] In one embodiment, the dimensionally stable filter component and the dimensionally stable further component collectively (together) form a dimensionally stable module. The filter component and thus the chemical filter cannot change their position relative to the further component. This embodiment further reduces the risk of the filter component or further component entering (getting into) the measuring chamber. In addition, the dimensionally stable module can often be replaced more quickly than if the chemical filter and the further component had to be replaced separately.

[0029] According to the invention, the filter component comprises the chemical filter. In one embodiment, the filter component as a whole is a dimensionally stable component. In another embodiment, the chemical filter is not necessarily dimensionally stable, and the filter component further comprises a dimensionally stable holder that holds the chemical filter.

[0030] According to the invention, the filter component comprises the chemical filter. In one embodiment, the entire filter component functions as the chemical filter. In another embodiment, the filter component comprises another part in addition to the chemical filter. The chemical filter is rigidly connected to the further part. For example, the further part is dimensionally stable, and the chemical filter is applied to a surface of the dimensionally stable further part, for example as a coating.

[0031] According to the invention, the filter component comprises at least one opening, which is referred to as the filter opening. Different embodiments are possible with regard to the location of the or a filter opening.

[0032] In a preferred embodiment, the filter component has two end faces and a lateral surface (shell surface, jacket surface) between the two end faces. The two end faces are, for example, circular or more generally elliptical, and the filter component has, for example, the shape of a cylinder or truncated cone. It is also possible that each end face has the shape of an n-gon (n-corner, n-eck), where n >= 3 is the number of comers. Preferably, the two end faces are perpendicular to a longitudinal axis and thus to a central axis of the filter component.

[0033] In one embodiment, the or at least one filter opening is inserted into the lateral surface. The gap and thus the section of at least 0.5 cm in length, along which the gas sample flows through the gap, are in this case preferably parallel to the filter longitudinal axis and / or parallel to the lateral surface. In another embodiment, the or at least one filter opening is inserted into an end face. It is even possible for an end face as a whole to form a filter opening. If the or a filter opening is inserted into the end face, the section of 0.5 cm in length is preferably perpendicular to the longitudinal axis of the filter. In an implementation of this embodiment, the lateral surface is impermeable to gas, and the chemical filter is placed on the lateral surface, or the lateral surface forms the chemical filter.

[0034] These two embodiments can be combined with each other. It is also possible that the or each filter opening is inserted into the lateral surface and both end faces are impermeable to gas.

[0035] Preferably, the measuring chamber is surrounded by a measuring chamber housing. The measuring chamber housing surrounds the measuring chamber, the filter component, and the further component. In one embodiment, both components are dimensionally stable, and the dimensionally stable chemical filter component and the dimensionally stable further component are removably inserted into the measuring chamber housing so that both dimensionally stable components can quickly be replaced.

[0036] The measuring chamber housing protects the filter component and thus the chemical filter as well as the further component to a certain extent from mechanical and chemical influences from the outside, in particular from weather influences, contamination, and mechanical damage. It is possible that the filter component is inserted into the measuring chamber housing. It is also possible that part of the measuring chamber housing simultaneously forms the further component.

[0037] Preferably, the measuring chamber housing is detachably connected to a further housing of the analyzer. After a user has removed the measuring chamber housing from the further housing, the filter component and thus the chemical filter in the measuring chamber housing can be replaced.

[0038] It is possible that the gas sample enters the measuring chamber solely (alone) by diffusion. It is also possible for a fluid conveying unit, such as a blower, a fan, a pump or a piston-cylinder unit, to convey the gas sample into the measuring chamber, for example by suction. In a preferred embodiment, however, a convection flow (convection current) out of the measuring chamber and into the measuring chamber is induced. In order to induce the convection flow, two openings are inserted into the measuring chamber housing. The gas sample flows through one opening into the measuring chamber and through the other opening out of the measuring chamber. According to a preferred embodiment, a lower opening and an upper opening are inserted into the measuring chamber housing. When the analyzer is used as intended, the lower opening is located vertically or obliquely below the upper opening.

[0039] In the embodiment with the induced convection flow, the analyzer also comprises a heatable element. This heatable element is in thermal contact with the measuring chamber and is arranged, for example, inside the measuring chamber. When the heatable element is heated, gas in the measuring chamber heats up. This reduces the density of the gas in the measuring chamber and makes it lighter than the gas in the surrounding area. This in turn causes a relevant quantity of gas to escape from the measuring chamber through the upper opening. This causes additional gas to flow from below through the lower opening into the measuring chamber. Heating thus causes a convection flow, also known as the chimney effect.

[0040] The embodiment in which a convection flow is induced has the following advantage over the embodiment in which the gas sample enters the measuring chamber exclusively by diffusion: Thanks to the convection flow, the gas sample enters the measuring chamber faster than with mere diffusion, and the analyzer can detect the target gas in the gas sample more quickly. The embodiment in which the convection flow is induced eliminates the need to provide a fluid conveying unit. A fluid conveying unit inevitably comprises at least one part that moves during operation and is therefore susceptible to failure more often than a heatable element.

[0041] The following disadvantages of an analyzer comprising a flow-through filter have already been mentioned above. In particular, the pores of a flow through filter become clogged during use, and the pneumatic resistance is often greater than with the solution according to the invention. In addition, in many cases, a flow-through filter can only be used at relatively low ambient humidity. In many cases, these disadvantages also occur in an analyzer that comprises a flow-through filter and induces a convection flow. Often, the ever-decreasing pores even lead to a relevant convection flow no longer occurring at all.

[0042] In contrast, the analyzer according to the invention comprising the filter component, the further component, and the gap makes it possible in many cases to make use of the effect and thus the advantages of the convection flow for longer than when using a flow-through filter, even at relatively high ambient humidity. The flow-through filter often has a higher pneumatic flow resistance, and the pores become clogged. As a result, the convection flow often breaks off relatively quickly, while the analyzer according to the invention can be used for longer without having to replace the chemical filter.

[0043] Different embodiments are possible with regard to how the sensor measures the concentration of a target gas to be detected in the gas sample while the gas sample is in the measuring chamber.

[0044] In one embodiment, the sensor is implemented as an electrochemical sensor, which preferably operates in the manner of a fuel cell. The electrochemical sensor comprises a measuring electrode, a reference electrode, and an ionically conductive electrolyte between these two electrodes. A target gas to be detected causes an electrochemical reaction and, as a result of this electrochemical reaction, an electric current flows from the one electrode to the other electrode. An indicator for the electrical charge is measured. The electrical charge correlates with the sought concentration of the target gas in the gas sample.

[0045] In another embodiment, the analyzer comprises a detector and a compensator. Both the detector and the compensator are heated. The heated detector oxidizes a combustible target gas in the measuring chamber, thereby releasing heat energy that further heats the detector. The heated compensator is able to oxidize a combustible target gas to a lesser extent than the heated detector, or a smaller amount of the gas sample reaches the compensator per unit time than reaches the detector. A detection variable sensor measures an indicator for the increase in temperature of the detector and thus for the heat energy released. This indicator correlates with the sought target gas concentration. Ideally, the compensator makes it possible to computationally compensate for the ambient conditions to influence the increase in temperature of the detector. Such a sensor is also referred to as a heat-tone sensor or a catalytic sensor.

[0046] An embodiment in which the analyzer induces a convection flow using a heatable element has already been described above. The embodiment with the convection flow can be combined with the embodiment just described, in which the analyzer comprises a detector and a compensator. In this combination, the detector and / or the compensator preferably function (act) as the or a heatable element. This type of combination makes it possible to make use of the advantages of convection flow without having the disadvantages of the flow-through filter described above and without having to provide an additional heatable element.

[0047] In a further embodiment, the sensor is implemented as a photoelectric sensor and comprises a radiation source, a measuring detector, and preferably a reference detector. The radiation source emits electromagnetic radiation, preferably radiation in the infrared range, into the measuring chamber. The radiation passes at least once through the gas sample in the measuring chamber. A target gas to be detected attenuates the intensity of electromagnetic radiation in a specific wavelength range. After the radiation has passed at least once through the gas sample, it impinges on both the measuring detector and the optional reference detector. Both the measuring detector and the reference detector measure an indicator for the intensity of incident radiation. The intensity of the incident radiation is an indicator for the sought target gas concentration. Ideally, the reference detector makes it possible to computationally compensate for the influence of ambient conditions, in particular water droplets, on the measurement result. In one embodiment, a wavelength filter upstream of the measuring detector only allows electromagnetic radiation in the wavelength range in which the target gas attenuates radiation to pass through (to transmit). A wavelength filter upstream of the reference detector allows radiation in a different wavelength range to pass through. The sensor can also comprise two measuring detectors for two different target gases, wherein a wavelength filter is particularly preferably arranged upstream of each measuring detector and the two wavelength filters allow radiation in two different wavelength ranges to pass through.

[0048] In a preferred embodiment, the optical path of the electromagnetic radiation through the measuring chamber is extended by a mirror in or on the measuring chamber reflecting the radiation at least once and by the radiation therefore passing through the gas sample at least twice.

[0049] The embodiment comprising the mirror can be combined with the embodiment described above, in which a heatable element can generate a convection flow. This combination is described below. The heatable element also supports the mirror. In this combination, heating the heatable element causes the gas in the measuring chamber to heat up. Since the heatable element also supports the mirror, the risk of water condensing on the mirror or on another wall of the measuring chamber is reduced. Condensing or condensed water can reduce the ability of the mirror to reflect the radiation and can lead to corrosion.

[0050] An embodiment in which a lower opening and an upper opening are inserted into the measuring chamber housing has been described above. Heating the gas in the measuring chamber causes the convection flow (chimney effect) described above. Thanks to the convection flow, gas flows from the lower opening through the measuring chamber to the upper opening, thereby quickly filling the measuring chamber with the gas sample to be examined. This embodiment can be combined with the embodiment in which the sensor is a photoelectric sensor and in which the heatable element supports the mirror.

[0051] Furthermore, an embodiment in which the measuring chamber housing is connected to a further housing, preferably detachably connected thereto, has been described above. The measuring chamber, the chemical filter, and the further component are arranged in the measuring chamber housing. This embodiment can be combined with the embodiment in which the sensor is implemented as a photoelectric sensor. The optional mirror described above is arranged in the measuring chamber housing. The radiation source, the measuring detector, and the optional reference detector are arranged in the further housing. Preferably, the further housing is fluid-tight, and the measuring chamber is separated from the interior of the further housing in a fluid-tight manner. The emitted electromagnetic radiation passes through a fluid-tight window in the further housing, then passes through the measuring chamber once, is reflected by the mirror, passes again through the measuring chamber, then passes through the or another fluid-tight window again and impinges on the or each measuring detector and the optional reference detector. The further housing protects the radiation source and the or each detector from external mechanical and chemical influences. Optionally, a power supply unit is also housed in the further housing.

[0052] In the following, the invention is described on the basis of an exemplary embodiment. In the drawings, Fig. 1 is a perspective view of an analyzer according to the invention comprising a photoelectric sensor; Fig. 2 is a schematic cross-sectional view of the measuring chamber, the filter component, and the path of a gas sample, wherein the filter openings are inserted into the lateral surface of the chemical filter; Fig. 3 shows a modification of the embodiment of Fig. 2, wherein the two end faces of the filter component form the filter openings of the chemical filter; Fig. 4 is a cross-sectional view of the weatherproof cap and the corresponding path of a gas sample and of water for the embodiment according to Fig. 1; Fig. 5 schematically shows an analyzer according to the invention comprising a heat-tone sensor; Fig. 6 shows measurement results relating to the response time of an analyzer.

[0053] Fig. 1 shows the analyzer 100 of the exemplary embodiment in two perspective views. The analyzer 100 can detect at least one predetermined target gas. In the exemplary embodiment, the analyzer 100 can measure the concentration of the target gas in a gas sample. The target gas is, for example, a gas that is harmful to humans, such as methane or carbon monoxide, or oxygen or carbon dioxide or an anesthetic. In the exemplary embodiment, the target gas absorbs a portion of electromagnetic radiation in a specific wavelength range, wherein the radiation passes through the target gas, and thereby attenuates the electromagnetic radiation.

[0054] The analyzer 100 can be fastened to a wall or to a user’s protective clothing using an optional bracket 15. The terms “bottom” and “top” used in the following refer to the orientation of the analyzer 100 during use. The drawings show the analyzer 100 in this orientation.

[0055] The analyzer 100 according to Fig. 1 comprises - a solid fluid-tight housing 2, for example made of a metal, - a weatherproof cap 1, and - a removable power supply unit 6 in its own housing.

[0056] In the exemplary embodiment, the solid housing 2 is arranged between the weatherproof cap 1 and the power supply unit 6. The weatherproof cap 1 has approximately the shape of a truncated cone and is approximately rotationally symmetrical with respect to a central axis MA. Both the weatherproof cap 1 and the power supply unit 6 can be separated from the housing 2 and reconnected to the housing 2. The fitted weatherproof cap 1 surrounds a region of the housing 2 that has a smaller diameter than the rest of the housing 2. Preferably, mechanical coding ensures that the weatherproof cap 1 can only be pushed onto the housing 2 in a certain rotational position relative to the housing 2.

[0057] At the top of Fig. 1, the three components 1, 2 and 6 are shown connected to one another, while, at the bottom, the weatherproof cap 1 is removed from the housing 2 and the power supply unit 6 is omitted. A U-shaped mirror holder 3 with two arms 3.1 and 3.2 holds the mirror 5 firmly on the housing 2. The fitted weatherproof cap 1 surrounds the mirror 5 and the mirror holder 3.

[0058] Fig. 2 and Fig. 3 schematically show a cross-sectional view of the interior of the weatherproof cap 1. The measuring chamber 30 and a mirror 5 are arranged inside the weatherproof cap 1. In the exemplary embodiment shown, the measuring chamber 30 has the shape of a cylinder and extends along the central axis MA.

[0059] A photoelectric sensor 50 comprises a radiation source 10 and a detector component 11. The radiation source 10 and the detector component 11 are arranged inside the housing 2. The detector component 11 comprises a measuring detector, a reference detector, a wavelength filter upstream of the measuring detector, and preferably a wavelength filter upstream of the reference detector. The wavelength filter upstream of the measuring detector only allows electromagnetic radiation in a wavelength range in which the target gas to be detected attenuates electromagnetic radiation to pass through (transmit). The wavelength filter upstream of the reference detector allows electromagnetic radiation in a different wavelength range to pass through. It is possible that two parallel measuring methods are able to detect two different target gases, with two wavelength filters that are arranged upstream of the two measuring detectors and allow electromagnetic radiation in two different wavelength ranges to pass through.

[0060] The measuring chamber 30 contains a gas sample, which contains or can contain at least one target gas to be detected. The radiation source 10 emits electromagnetic radiation eS, preferably in the infrared range. The emitted electromagnetic radiation eS passes through a window 4 in the housing 2 once, then passes through the measuring chamber 30, is reflected by the mirror 5, passes through the measuring chamber 30 and the window 4 again, and impinges on the detector component 11. The mirror 5 doubles the length of the optical path.

[0061] Both the measuring detector and the reference detector of the detector component 11 each measure an indicator for the intensity of incident (impinging) electromagnetic radiation. Thanks to the wavelength filter upstream of the measuring detector, a signal of the measuring detector correlates with the concentration of the target gas in the gas sample Gp. However, a signal of the measuring detector is usually also influenced by ambient conditions, in particular by the ambient humidity and thus by water droplets or water vapor in the measuring chamber 30. In particular, water droplets can also attenuate electromagnetic radiation. Ideally, the reference detector responds to the influence of ambient conditions in the same way as the measuring detector but is - thanks to the wavelength filter upstream of the reference detector - not influenced by the target gas . A signal of the reference detector is used to computationally compensate for the influence of the ambient conditions on the signal of the measuring detector.

[0062] The undesirable event that water vapor condenses on the mirror 5 or on another wall of the measuring chamber 30 may occur. Condensed water could distort a measurement and could also lead to unwanted corrosion. The following passage describes how the risk of this undesirable event occurring is reduced in the exemplary embodiment. According to this remedy, the mirror holder 3 is heated, for example by heating wires inside the mirror holder 3. Heating the mirror holder 3 reduces the risk of water condensing on the mirror 5 or on another wall of the measuring chamber 30.

[0063] Heating the mirror holder 3 has a further desired effect described below: Heating causes gas inside the measuring chamber 30 to be heated. Heating reduces the density of the gas and causes a so-called chimney effect, also referred to as a convection flow. Thanks to the convection flow, the gas sample Gp enters the measuring chamber 30 from below and leaves the measuring chamber 30 again to above. Thanks to the convection flow, a gas sample Gp reaches the measuring chamber 30 more quickly than if the gas sample Gp was to enter the measuring chamber 30 merely by diffusion. This in turn leads to a target gas in the gas sample Gp being detected more quickly or to the possibility that the gas sample Gp contains the or a target gas being ruled out more quickly. Thanks to the convection flow, it is not necessary to use a separate fluid conveying unit, wherein the fluid conveying unit draws (sucks in) a gas sample Gp in and / or expels it. Such a fluid conveying unit inevitably consumes electrical energy, takes up installation space, and must be monitored.

[0064] Fig. 2, Fig. 3, and Fig. 4 illustrate in two cross-sectional views the path of the gas sample Gp through the interior of the weatherproof cap 1. A lower opening 8 and an upper opening 7 are inserted into the weatherproof cap 1. The gas sample Gp enters the interior of the weatherproof cap 1 through the lower opening 8, flows in a curved path through the weatherproof cap 1, and leaves the weatherproof cap 1 again through the upper opening 7. The curved path is enforced by corresponding components inside the weatherproof cap 1.

[0065] Water can enter the interior of the weatherproof cap 1 through the upper opening 7. A water barrier 9 is therefore located below the upper opening 7; cf. Fig. 4. The water barrier 9 surrounds the measuring chamber 30 like a tube and prevents water from entering the measuring chamber 30. Fig. 3 schematically shows the path H2O of water into and out of the weatherproof cap 1.

[0066] In addition to the target gas and water droplets, the gas sample Gp may comprise a substance being different from the or every target gas wherein the substance should not influence the measurement results of the analyzer 100. The substance is, for example, hydrogen sulfide or a long-chain hydrocarbon. It is possible that the substance is harmful to a component in the weatherproof cap 1 and / or in the measuring chamber 30. Therefore, the measure described below prevents this substance from being able to enter the interior of the measuring chamber 30.

[0067] The measuring chamber 30 is surrounded by a chemical filter 22. In the embodiment according to Fig. 2, the entire filter component 20 functions as the chemical filter 22. In the embodiment according to Fig. 3 described in more detail below, part of the filter component 20 functions (serves) as the chemical filter 22. The remainder of the filter component 20 is not chemically active in the embodiment according to Fig. 3.

[0068] In the exemplary embodiment, the filter component 20 has the shape of a tube or truncated cone. Fig. 3 and Fig. 4 schematically show a tubular (cylindrical) filter component 20 with two parallel circular end faces 20.S1 and 20.S2 and a lateral surface 20.M between the two end faces 20.S1 and 20.S2. In the example shown, the filter component 20 is dimensionally stable and comprises, for example, a body made of a polymer or another solid plastics or of metal or glass. For example, the filter component 20 is manufactured by sintering or by 3D printing. In one embodiment, the filter component 20 is held in a certain position relative to the weatherproof cap 1 by its own elasticity, in another embodiment by a screw cap or snap fastener or locking fastener or by suitable projections and grooves. In particular, these preferred embodiments prevent the filter component 20 from entering the optical path from the radiation source 10 via the mirror 5 to the component 11.

[0069] A plurality of openings 020 are inserted into the filter component 20 and function as the filter openings. The two embodiments according to Fig. 2 and Fig. 3 differ from one another as follows: In the embodiment according to Fig. 2, the filter openings 0.20 have the shape of curved rectangles, which are inserted into the lateral surface 20 of the filter component 20. In the embodiment according to Fig. 3, the two filter openings 020 are inserted into the two end faces 20.S1 and 20.S2, wherein the two end faces 20.S1 and 20.S2 preferably additionally form the two filter openings 0.20. Of course, other geometric shapes are also possible.

[0070] The gas sample Gp enters the interior of the weatherproof cap 1 through the lower opening 8 and the measuring chamber 30 through openings 020. The filter component 20 is ideally impermeable to gas, except for the openings 020. In practice, the filter component 20 usually has further openings that cannot be avoided. [0071 ] In the exemplary embodiment, the filter component 20 is surrounded by a further component 21. In the exemplary embodiment, a part of the housing 2, the mirror 5, and a component 21 in the shape of a tube or truncated cone collectively function as the further component. The tubular component 21 extends along the central axis MA. Preferably, the tubular component 21 additionally functions as a handling protection means and is particularly preferably rigidly connected to the filter component 20. In the following, the term “handling protection means” is used for the further component 21, even if the further component 21 does not function as a handling protection means. In the exemplary embodiment, the handling protection means 21 has the same geometric shape as the filter component 20 but has a larger diameter so that a circumferential cylindrical gap Sp.i (inner gap) is formed between the filter component 20 and the handling protection means 21. A circumferential gap Sp.a (outer gap) is formed between the handling protection means 21 and the weatherproof cap 1. In one embodiment, the circumferential outer gap Sp.a increases toward the housing 2. In another embodiment, the circumferential outer gap Sp.a always has a constant width along the central axis MA.

[0072] In one embodiment, the filter component 20 and the handling protection means 21 collectively form a dimensionally stable module. For example, the two components 20 and 21 are rigidly connected to one another.

[0073] The handling protection means 21 is also impermeable to gas. A plurality of openings 021 are arranged in the handling protection means 21. In the example shown, the openings 021 are inserted into the lateral surface of the cylindrical further component 21. The handling protection means 21 is held in a certain position relative to the weatherproof cap 1 by its own elasticity and / or by projections and grooves, and the filter component 20 is held in a certain position relative to the handling protection means 21. As a result, neither the filter component 20 nor the handling protection means 21 can change their position relative to the weatherproof cap 1, and neither the filter component 20 nor the handling protection means 21 enter the optical path outlined above through the measuring chamber 30.

[0074] In the exemplary embodiment according to Fig. 2, the openings 020 in the filter component 20 are displaced (laterally offset) relative to the openings 021 in the handling protection means 21, specifically in parallel with the central axis MA. It is also possible that - in addition to or instead of the parallel displacement - the openings 020 and 021 are rotated (twisted) relative to one another about the central axis MA. In the embodiment according to Fig. 3, the entire lateral surface 20.M of the filter component 20 is impermeable to gas, while the two end faces 20.S1 and 20.S2 are permeable to gas. The chemical filter 22 is applied to the lateral surface 20.M and cannot change its position relative to the lateral surface 20.M.

[0075] Both the filter component 20 and the handling protection means 21 are impermeable to gas except for the openings just mentioned. On its way from the lower opening 7 to the upper opening 8, the gas sample Gp is therefore forced along the following path:

[0076] - first through openings 021 in the handling protection means 21, - then approximately in parallel with the central axis MA through the inner gap Sp.i, and - then through openings 020 in the filter component 20 into the interior of the measuring chamber 30.

[0077] In the inner gap Sp.i, the gas sample Gp thus flows past the outside of the chemical filter 22.

[0078] In particular, because the openings 020 and 021 do not overlap, the following undesired event is prevented: A portion of the gas sample Gp flows through the lower opening 7 and through an opening 020 and 021 into the interior of the measuring chamber 30 without flowing past (along) the filter component 20. This would result in a significant amount of the substance flowing past (bypassing) the chemical filter 22 and entering the measuring chamber 30, which is undesirable.

[0079] The gas sample Gp thus flows past the chemical filter 22 on its way through the inner gap Sp.i. The section traveled by the gas sample Gp in the gap Sp.i depends on the respective positions of the openings 020 and 021. The path in the inner gap Sp.i which the gas sample Gp is forced to take comprises a section which is at least 0.5 cm, preferably at least 2 cm, particularly preferably at least 5 cm, in particular at least 10 cm long.

[0080] How long the gas sample Gp remains in the inner gap Sp.i depends on this section as well as on the thickness and the geometry of the gap Sp.i. The chemical filter 22 binds molecules of the substance in the gas sample Gp that is not to enter the interior of the measuring chamber 30. Ideally, this substance accumulates exclusively on the outside of the chemical filter 22. By the chemical filter 22 binding molecules of the substance, a concentration gradient occurs in the gas sample Gp. As a result, further molecules of the substance move toward the chemical filter 22 and are also bound to the chemical filter 22. Of course, these effects only occur if the gas sample Gp contains the substance.

[0081] In one application, hydrogen sulfide is harmful to at least one element of the detector component 11. Hydrogen sulfide is therefore to be prevented from entering the interior of the measuring chamber 30. In one embodiment, the chemical filter comprises 22 alkaline copper salts. Hydrogen sulfide binds to the alkaline copper salt, and the copper salt is converted to solid copper sulfide.

[0082] In one application, carboxylic acids, such as acetic acid (CH3COOH), are to be prevented from entering the interior of the measuring chamber 30. In particular, carboxylic acids corrode metals particularly easily and can therefore lead to failure of the sensor 10, 11. For example, corrosion can impair the function of a measuring element, a window, a mirror holder, and / or a mirror coating. Alkali metal hydroxide compounds neutralize carboxylic acids in different ways. For example, a chemical filter 22 containing potassium hydroxide neutralizes acetic acid by converting the acetic acid into solid potassium acetate (C2H3KO2).

[0083] It is usually necessary to replace the chemical filter 22 from time to time. In order to replace the chemical filter 22, a user performs the following steps: - The user removes the weatherproof cap 1 from the housing 2. The mirror 5 holds the filter component 20 and the handling protection means 21 on the housing 2 and prevents a component 20 or 21 from being removed together with the weatherproof cap 1 from the housing 2. - The user pulls the handling protection means 21 together with the filter component 20 away from the housing 2 in a direction parallel to the central axis MA. - A new chemical filter 22 is provided. It is possible that a new filter component 20 is provided. It is also possible that the new chemical filter 22 is applied to the removed filter component 20. -The filter component 20 with the new chemical filter 22 is or will be surrounded by the old or a new handling protection means 21. - The user pushes the filter component 20 with the new chemical filter 22 toward the housing 2 until the housing 2 holds the filter component 20 with the new chemical filter 22. For example, a locking connection or snap-in connection is created. During this movement, the handling protection means 21 surrounds the filter component 20. - The handling protection means 21 prevents the user from touching the chemical filter 22. Such contact could have an undesirable effect on the skin of the user's hand and / or damage the chemical filter 22. - The user places the weatherproof cap 1 on the housing 2 and thus on the components 20 and 21.

[0084] It is also possible that the weatherproof cap 1 holds the components 20 and 21 on the inside and that the components 20 and 21 together with the weatherproof cap 1 are removed from the housing 2. Some steps of the sequence just described change accordingly. In particular, the user then pulls the components 20 and 21 out of the weatherproof cap 1.

[0085] In an alternative embodiment, the filter component 20 is not rigidly connected to the handling protection means 21. Instead, the handling protection means 21 is fastened to the inside of the weatherproof cap 1 and is removed from the housing 2 when the weatherproof cap 1 is removed. The filter component 20 initially remains on the housing 2 and is removed and replaced separately. This embodiment makes it possible to replace the filter component 20 independently of the handling protection means 21, which is in particular advantageous if the chemical filter 22 has to be replaced more often than the handling protection means 21.

[0086] By way of example, Fig. 4 shows two indicator lights 40 and 41 on the housing 2. The indicator light 40 lights up when the analyzer 100 is switched on and when the power supply unit 6 provides sufficient electrical energy. The indicator light 41 lights up when the analyzer 100 has detected an error. Examples of such an error are: - The weatherproof cap 1 is not correctly fitted to the housing 2 or even not at all, although the analyzer 100 is switched on, or the filter component 20 is not correctly connected to the housing 2 and / or not correctly inserted into the weatherproof cap 1. In both of these cases, a portion of the gas sample Gp could flow past the chemical filter 20, i.e. bypass the chemical filter 20, and enter the interior of the measuring chamber 30. In one embodiment, the undesirable event that the weatherproof cap 1 is not correctly fitted is detected by means of a contact switch (not shown). -A component comprising a filter component 20 with a chemical filter 22 and a handling protection means 21 is not inserted into the interior of the weatherproof cap 1. This event is also detected using a contact switch, for example. Alternatively, a machine-readable identifier is applied to the outside of the handling protection means 21, for example in the form of an RFID chip or other NFC chip or a barcode. A reader (not shown) inside the weatherproof cap 1 detects this machine-readable identifier. If the reader has not detected such a machine-readable identifier, the handling protection means 21 and thus the chemical filter 22 are missing, or the weatherproof cap 1 is incorrectly fitted. -An opening 7 or 8 for the convection flow is blocked.

[0087] In one embodiment, the machine-readable identifier on the handling protection means 21 uniquely identifies the component with the chemical filter 22 and the handling protection means 21. The point in time at which the reader first recorded this machine-readable unique identifier is stored in a data memory of the analyzer 100. A control device measures the amount of time that has so far elapsed since this point in time of insertion, i.e. the use duration up to now. Preferably, only the periods in which the analyzer 100 is switched on are taken into account for this time period. If this amount of time has exceeded a predetermined lower time limit, a message is generated and output in at least one form that can be perceived by a human. This message indicates that the chemical filter 22 is now used up and needs to be replaced. How the chemical filter 22 is replaced has already been described above.

[0088] The detector component 11 comprises a measuring detector and a reference detector. Upstream of the measuring detector, there is a wavelength filter that only allows electromagnetic radiation in the wavelength range in which the target gas absorbs electromagnetic radiation and thereby reduces the radiation intensity to pass through. The wavelength filter upstream of the reference detector allows radiation in a different wavelength range to pass through. In one embodiment, this other wavelength range includes the wavelength range of water and the wavelength range of the substance that is not to enter the measuring chamber 30. It is also possible to use two reference detectors, with a wavelength filter for water arranged upstream of the first reference detector and a wavelength filter for the undesirable substance arranged upstream of the second reference detector. In some cases, by evaluating the signal generated by the detector component 11, it is possible to automatically decide whether a relevant quantity of the substance has entered the measuring chamber 30 or not. If a relevant quantity has entered the measuring chamber 30, this is an indication that the chemical filter 22 needs to be replaced. The analyzer 100 displays a corresponding message.

[0089] The analyzer 100 may comprise a heat-tone sensor 51 instead of the photoelectric sensor 50 of Fig. 2 and 3. Fig. 5 schematically shows three example embodiments according to the invention of such a heat-tone sensor 51 as a component of an analyzer 100 according to the invention. The same reference signs have the same meanings as in Fig. 2 and Fig. 3.

[0090] The heat-tone sensor 51 comprises a housing 2, a detector 31, and a compensator 32. A housing opening 02 in the housing 2 establishes a fluid connection between the measuring chamber 30 inside the housing 2 and a surrounding area. The detector 31 is heated. The heated detector 31 oxidizes combustible target gas in the measuring chamber 30, of course only if there is sufficient combustible target gas in the measuring chamber 30. The oxidation of the target gas releases heat energy which further heats the detector 31. The released heat energy changes a detection variable that correlates with the temperature of the detector 31, for example the electrical resistance. It is well known that the electrical resistance of many electrically conductive components increases when the temperature increases. A detection variable sensor measures an indicator for the temperature of the detector 31. The measured detection variable is an indicator for the detector temperature and thus of the sought target gas concentration. By way of example, a voltage sensor 34 is shown, which measures the electrical voltage applied to the detector 31.

[0091] The temperature of the detector 31 is influenced not only by the target gas concentration, but also by ambient conditions, in particular by the ambient temperature and ambient humidity. A compensator 32 is able to oxidize combustible target gas to a lesser extent than the detector 31, or even not at all, but ideally responds in the same way to ambient conditions. A detection variable of the compensator 32 is measured. By way of example, a voltage sensor 35 is shown, which measures the electrical voltage applied to the compensator 32. By means of the compensator detection variable, the influence of ambient conditions on the detector detection variable can be computationally compensated to a certain degree.

[0092] In the exemplary embodiment, both the detector 31 and the compensator 32 each are formed as a pellistor. An approximately spherical casing made of ceramic surrounds a heating segment. The ceramic casing chemically and electrically insulates the heating segment from the environment while maintaining thermal contact. A catalytically active substance is embedded in the casing of the detector 31 but not in the casing of the compensator 32.

[0093] In one embodiment, the detector 31 and optionally the compensator 32 simultaneously function as the heating element which, as shown in Fig. 4, induces a convection flow through the lower opening 8 into the measuring chamber 30 and out of the measuring chamber 30 and through the upper opening 7. When using the analyzer 100, the housing opening 02 is preferably located below the measuring chamber 30.

[0094] In the example of Fig. 5a) and that of Fig. 5b), the filter component 20 with the chemical filter 22 is located between the housing opening 02 and the further component 21. The inner gap Sp.i is located between the filter component 20 and the further component 21. In the example of Fig. 5a), the filter opening 020 is located between the gas-impermeable filter component 20 and the further component 21. A gas sample Gp flows around the filter component 20 and through the filter opening 020 and then through the inner gap Sp.i and through the opening 021 into the measuring chamber 30. In the example of Fig. 5b), a filter opening 020 is inserted into the filter component 20, and the gas sample Gp flows through this filter opening 020 and the inner gap Sp.i into the measuring chamber 30.

[0095] In the example of Fig. 5c), however, the housing 2 itself functions as the further component 21. The inner gap Sp.i is formed between the housing 2 and the filter component 20. The chemical filter 22 is arranged on the filter component 20 and points toward the housing opening 02, which simultaneously functions as an opening 021 in the further component 21.

[0096] Fig. 6 illustrates results of an internal experiment conducted by the inventors. The results illustrate different response times. The time in [min:sec] that has elapsed since the analyzer 100 was switched on is plotted on the x-axis. The relative target gas concentration con measured at each point in time is plotted on the y-axis in [%]. A value of 1 = 100% means that the maximum measured value has been reached. This maximum measured value ideally corresponds to the actual concentration of the target gas in the gas sample Gp. Inevitably, an amount of time elapses after the analyzer 100 is switched on until the gas sample Gp has filled the measuring chamber 30. Therefore, time also passes until the maximum value is reached.

[0097] An analyzer 100 without a chemical filter was used in the first internal experiment, an analyzer 100 with a filter having pores was used in the second internal experiment, wherein the gas sample flows through the pores (flow-through filter), and an analyzer 100 according to the invention was used in the third internal experiment. In Fig. 6, three measurement curves V.o, V.trans, V.inv are plotted:

[0098] Measurement curve V.o refers to the first internal experiment (analyzer without chemical filter), measurement curve V.trans refers to the second internal experiment (analyzer with flow-through filter), and measurement curve V.inv refers to an analyzer 100 according to the invention. In addition, three points in time t.o, t.trans and t.inv are plotted. At this point in time, the corresponding measurement curve reaches the value 0.9, which is equal to 90% of the maximum value.

[0099] As expected, the response time is shortest in an analyzer without a chemical filter. However, without a chemical filter, the undesirable substance can enter the measuring chamber 30. It can be seen that the chemical filter 22 arranged according to the invention significantly reduces the response time in comparison to an analyzer having a flow-through filter. The internal experiments show, by way of example, that the invention reduces the response 5 time and therefore leads to a target gas being detected more quickly without the substance reaching the measuring chamber 30 and without the substance being able to distort a measurement result. List of reference signs 1 Weather protection cap, has approximately the shape of a truncated cone, can be fitted to the housing 2 and removed from the housing 2 again, surrounds the measuring chamber 30, accommodates the filter component 20 and the handling protection means 21, functions as the measuring chamber housing 2 Housing made of metal, accommodates the radiation source 10 and the component 11 comprising the measuring detector and the reference detector, can be detachably connected to the weatherproof cap 1 and to the power supply unit 6, comprises the window 4 3 Mirror holder for the mirror 5, comprises the arms 3.1 and 3.2, simultaneously functions as the heatable element, connected to the housing 2 3.1,3.2 Arms of the mirror holder 3 4 Window in the housing 2, allows the electromagnetic radiation eS to pass into the measuring chamber inside the weatherproof cap 1 5 Mirror inside the weatherproof cap 1, held by the mirror holder 3 6 Power supply unit with its own housing, can be detachably connected to the housing 2 7 Upper opening in the weatherproof cap 1 8 Lower opening in the weatherproof cap 1 9 Water barrier inside the weatherproof cap 1 10 Radiation source, emits the electromagnetic radiation eS through the window 4 and into the measuring chamber 30 11 Detector component comprising the measuring detector and the reference detector and comprising wavelength filters 15 Holder on the housing 2, allows the analyzer 100 to be mounted 20 Filter component, surrounds the measuring chamber 30, surrounded by the handling protection means 21, has the chemical filter 22, comprises the end surfaces 20.S1, 20.S2, the lateral surface 20.M, and the openings 020 20.S1,20.S2 End faces of the filter component 20 20.M Lateral surface of the filter component 20 21 Handling protection means 21, surrounds the filter component 20, has openings 021, functions as the further component 22 Chemical filter, belongs to the filter component 20 30 Measuring chamber inside the weatherproof cap 1 31 Detector of the heat-tone sensor 51, oxidizes combustible target gas and is thereby further heated 32 Compensator of the heat-tone sensor 51, not able to oxidize combustible target gas or able to oxidize it less than the detector 31 34 Voltage sensor that measures the voltage at the detector 31 35 Voltage sensor that measures the voltage at the compensator 32 40 Indicator light: Analyzer 100 switched on 41 Indicator light: Error occurred 50 Photoelectric sensor, comprises the radiation source 10, the mirror 5 and the detector component 11 51 Heat-tone sensor, comprises the detector 31, the compensator 32 and the voltage sensors 34 and 35 100 Analyzer, comprises the weatherproof cap 1, the housing 2, the sensor 50 or 51 and the power supply unit 6 eS Electromagnetic radiation, emitted by the radiation source 10 Gp Flow path of the gas sample from bottom to top through the weatherproof cap 1 and the measuring chamber 30 H2O Flow path of water through the weatherproof cap 1 MA Central axis of the cylindrical measuring chamber 30, also central axis of the weatherproof cap 1 Sp.i Tubular inner gap between the filter component 20 and the handling protection means 21 Sp.a Outer gap between the weatherproof cap 1 and the handling protection means 21, increases in one embodiment in the direction of the housing 2 and remains constant along the central axis MA in another embodiment t.inv Point in time of the measurement curve V.inv at which the measured target gas concentration reaches 90% of the maximum value t.o Point in time of the measurement curve V.o at which the measured target gas concentration reaches 90% of the maximum value t.trans Point in time of the measurement curve V.trans at which the measured target gas concentration reaches 90% of the maximum value V.inv Measurement curve of the relative target gas concentration over time for an analyzer with a chemical filter 22 arranged according to the invention V.o Measurement curve of the relative target gas concentration over time for an analyzer without a chemical filter V. trans Measurement curve of the relative target gas concentration over time for an analyzer comprising a flow-through filter

Claims

1. An analyzer (100) for analyzing a gas sample (Gp) for at least one target gas to be detected,wherein the analyzer (100) comprises- a sensor (50, 51),- a measuring chamber (30),- a filter component (20) comprising a chemical filter (22) and defining at least one filter opening (020), and- a further component (2, 5, 21) having at least one component opening (021), wherein the measuring chamber (30) is configured to take-up the gas sample (Gp), wherein the sensor (50, 51) is configured to generate a signal which correlates with the concentration of the target gas in the gas sample (Gp),wherein both the filter component (20) and the further component (2, 5, 21) are impermeable to gas except for the respective at least one opening (020, 021),wherein a gap (Sp.i), which is adjoined by the chemical filter (22), is formed between the filter component (20) and the further component (2, 5, 21),wherein the filter component (20) and the further component (2, 5, 21)- collectively surround the measuring chamber (30) and- collectively are implemented as a dimensionally stable component,wherein the at least one filter opening (020) and the at least one component opening (021) are arranged such that a gas sample (Gp) is forced on a path through the gap (Sp.i) and passing the chemical filter (22) before the gas sample (Gp) reaches the interior of the measuring chamber (30),wherein this path comprises a section of at least 0.5 cm in length, andwherein the chemical filter (22) is configured to bind and / or break down and / or chemically convert at least one substance that is or may be present in the gas sample (Gp), as the gas sample (Gp) flows through the gap (Sp.i) and passing the chemical filter (22).

2. The analyzer (100) according to claim 1,characterized in thatthe further component (2, 5, 21) surrounds the filter component (20).

3. The analyzer (100) according to any one of the preceding claims, characterized in thatthe filter component (20) and the further component (2, 5, 21) collectively form a dimensionally stable module.

4. The analyzer (100) according to any one of the preceding claims, characterized in thatthe filter component (20) comprises two spaced-apart end faces (20.S1, 20.S2) anda lateral surface (20.M),the lateral surface (20.M) extending between the two end faces (20.S1, 20.S2),the or at least one filter opening (020) being inserted, in a first alternative, into the lateral surface (20.M), andthe or at least one filter opening (020) being inserted, in a second alternative, into an end face (20.S1, 20.S2).

5. The analyzer (100) according to any one of the preceding claims, characterized in thatthe analyzer (100) comprises a measuring chamber housing (1) and a heatable element (3),the measuring chamber housing (1) surrounding- the measuring chamber (30),- the filter component (20), and- the further component (2, 5, 21), the heatable element (3)- being in thermal contact with the measuring chamber (30) and- being configured to heat the interior of the measuring chamber (30),a lower opening (8) and an upper opening (7) being inserted into the measuring chamber housing (1), andthe lower opening (8) configured to be arranged vertically or obliquely below the upper opening (7) in use.

6. The analyzer (100) according to claim 5, characterized in thatthe sensor comprises a radiation source (10) and a detector component (11), and the analyzer (100) comprises a mirror (5),the radiation source (10) being configured to emit electromagnetic radiation (eS), the analyzer (100) being configured such that- the emitted radiation (eS) passes at least once through the measuring chamber (30),- impinges on the detector component (11), and- is reflected at least once by the mirror (5) on the way from the radiation source (10) to the detector component (11), andthe heatable component (3) additionally holds the mirror (5).

7. The analyzer (100) according to claim 5, characterized in thatthe sensor (50, 51) comprises a detector (31) and a detection variable sensor (34, 35),the detector (31) being configured to oxidize combustible target gas in the measuring chamber (30),the detection variable sensor (34, 35) being configured to measure an indicator for the thermal energy released during the oxidation of combustible target gas, andthe detector (31) simultaneously functioning as the heatable element (3).

8. The analyzer (100) according to any one of the preceding claims, characterized in thatthe analyzer (100) comprises a measuring chamber housing (1) and a detector housing (2),the measuring chamber housing (1) surrounding- the measuring chamber (30),- the filter component (20), and- the further component (2, 5, 21), andthe measuring chamber housing (1) being detachably connected or connectable to the detector housing (2).

9. The analyzer (100) according to claim 8 when not dependent on claim 7, characterized in thatthe sensor (50, 51) comprises a radiation source (10) and a detector component (11),the radiation source (10) being configured to emit electromagnetic radiation (eS),the analyzer (100) being configured such that the emitted radiation (eS) passes at least once through the measuring chamber (30) and impinges on the detector component (11),the detector component (11) being configured to generate the signal, which correlates with the concentration of the target gas in the gas sample (Gp), depending on the intensity of incident electromagnetic radiation (eS), andthe detector housing (2) surrounding the radiation source (10) and the detector component (11).

10. The analyzer (100) according to any preceding claim, wherein the chemical filter (22) comprises the at least one filter opening (020).

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