Patent Description:
The European patent <CIT> discloses a fluid pressure control apparatus for a gas chromatograph which comprises a solenoid valve, that can be actuated through an electronic controller, and pressure sensor. The fluid pressure control apparatus is designed to meet an intrinsic safety standard, for example IEC <NUM>-<NUM>. The electronic controller is accommodated in a housing that encloses the valve with its solenoids and the pressure sensor. Portions of a pipe for transporting gases like hydrogen pass through the housing and are connected through fittings.

Moreover, the European patent application <CIT> teaches a gas chromatograph that comprises an explosion-proof housing which connects to a manifold block, through which a gas, hydrogen e.g., is transported in a tube. The manifold block encloses the valve portion of a valve and a pressure sensor. A solenoid portion of the valve is accommodated in the adjacent explosion-proof housing.

<CIT> discloses an intrinsically safe thermal conductivity detector for a process gas chromatograph. It comprises a thermistor, a reference resistor connected to the thermistor and an operational amplifier configured to drive a voltage through the reference resistor onto the thermistor. It further comprises an infallible resistance element connected between the thermistor and a high impedance input of the operational amplifier.

Gas analyzers, in particular gas chromatographs, are used for measuring the component makeup of gases and liquids like that are utilized in chemical production processes or natural gas coming from a gas well. For detecting different kinds of components, different supply and carrier gases are used, including combustible or potentially hazardous gases like hydrogen or other gases such as nitrogen, helium or argon and air. At the same time, there is demand for more efficient safety for the operation of gas analyzers. In addition to that, gas analyzers are to be reliable and cost-effective. It is an object of the invention to provide a gas analyzer that offers an improvement in at least one of these aspects.

That object is achieved through a gas analyzer according to the present invention. The gas analyzer comprises a pressure module through which a gas is to be transported. The pressure module at least partly encloses a tube, through which the gas flows during operation of the gas analyzer. The pressure module is self-contained. Gas only enters or exits the pressure module only through fittings provided for that purpose. Thus the pressure module may be configured to maintain a gas pressure on its inside that is not affected by an ambient pressure. The gas transported through the tube may be a carrier gas or another supply gas. Particularly, the gas may be hydrogen or any other gas that can form an explosive mixture with air, or gases like helium, nitrogen, argon or air. Furthermore, the gas analyzer comprises at least one sensor that is accommodated in the pressure module. The at least one sensor is configured to measure a physical quantity inside the pressure module and/or the tube. Moreover, the gas analyzer comprises at least one valve that is configured to control a gas flow through the tube. The valve comprises a valve portion and a solenoid portion. The valve and the sensor are operable through a master control circuit. The master control circuit is configured to define setpoints, for example for a closed loop control circuit accommodated in the pressure module. This closed loop control circuit may be configured for reading measurement data from the sensor and for actuating the valve respectively.

In combination, they are suitable to reliably control the gas flow through the tube depending on the present operational situation of the gas analyzer.

Particularly, the valve and the sensor may be configured to govern a gas flow to a subsequent component of the gas analyzer, e.g. a separation column.

According to the present invention, the master control circuit is accommodated in a self-contained control enclosure that is located separate of the pressure module. Thus, the control enclosure separates the master control circuit from the valve and the sensor, which are accommodated in the pressure module. Such a separate accommodation of these components allows economical installation even in potentially hazardous areas.

In turn, potentially hazardous supply gases like hydrogen are separated from the control enclosure in a reliable and cost-effective manner.

Additionally, the gas analyzer can use control circuits, especially master control circuits, with more energy-demanding functions, like processing of measurement data or execution of computer programs on the master control circuit. Since the master control circuit is placed in the control enclosure and separated from an atmosphere where hazardous gases may occur and separated from the pressure module, that is purposed to control flow of even flammable supply gases, and no potentially flammable supply gases are conducted into the control enclosure. Furthermore, requirements for cost effective measures to operate the gas analyzer can be met. That allows for manufacturing and operating the gas analyzer in a cost-effective manner. Altogether, the gas analyzer according to the present invention shows an appropriate safety level, a wider variety of additional data processing functions, and is cost-effective to produce and operate.

In an embodiment of the claimed gas analyzer, one or more valves are at least partly accommodated in an encapsulation. The encapsulation is configured to engulf at least a portion of the valve where a significant amount of energy is stored. Through the encapsulation, an outer atmosphere that might contain potentially flammable gases is kept from reaching the solenoid portion of the valve.

The encapsulation may be embodied as a casting compound that is an electric insulator, especially a resin, a thermoplastic material or a comparable material. Such an encapsulation is cost-effective to manufacture. Moreover, the encapsulation with the at least partly engulfed valve may be accommodated inside the pressure module or outside of it. Alternatively, the valve may be at least partially accommodated in a molding.

Furthermore, the valves may at least partly be placed outside of the pressure module. A placement of the valves as a part of the pressure module outside of the control enclosure decreases heat dissipation from valves within the control enclosure. This allows operation in a broader range of ambient temperature.

In addition to that, the master control circuit of the claimed gas analyzer may comprise at least one intrinsic safety barrier circuit. The intrinsic safety barrier circuit is configured to connect to at the least one sensor and the valve. Particularly, the intrinsic safety barrier circuit serves for supplying limited energy to a closed control circuit, which controls the valve and the at least one sensor. Moreover, the intrinsic safety barrier circuit is configured to facilitate a data transfer between the master control circuit and the closed loop control circuit, comprising of at least one sensor and/or the at least one valve. That allows for actuating the at least one valve, reading measurement data from the at least one sensor and/or calibrating either of them. The intrinsic safety barrier circuit comprises passive electronic components, especially diodes, Zener diodes and fuses, which are configured to limit the energy supplied to the pressure module to a fixed maximum energy value. A fixed maximum voltage and current limitation is chosen to ensure that intrinsically safety conditions are met. The intrinsic safety barrier circuit allows for supplying a sufficient amount of energy to the at least one sensor and to the at least one valve. In a preferred embodiment of the invention, the intrinsic safety barrier circuit may be configured according to the IEC <NUM>-<NUM> standard. Since the claimed intrinsic safety barrier circuit is at least partly made of passive electronic components, it can be manufactured in a cost-effective manner and shows a high degree of reliability.

In another embodiment of the present invention the pressure module in combination with the valve and the at least one sensor is designed in the way that requirements regarding safe operation can be met.

The gas analyzer shows a safety level on par with existing protection standards for gas chromatographs while omitting the use of heavy sophisticated components like metal housings or enclosures for the pressure module.

For example, the pressure module may be designed to withstand operational internal pressures of up to <NUM> bar. Operational internal pressures of up to <NUM> bar are commonly not considered to meet the requirements of explosion protection as outlined in various standards. Thus, the pressure module is to be construed as a non-explosion-protected enclosure in comparison to other known gas chromatographsTherefore, the pressure module may be embodied as a relatively simple, light and cost-effective enclosure. Having such an enclosure as the pressure module allows for simplifying the overall design of the claimed gas analyzer.

Moreover, the at least one sensor in the claimed gas analyzer can be a first pressure sensor. The first pressure sensor is exposed to a gaspressure that is present in the pressure module, especially a gas pressure close to the inlet of the pressure module. This may be used as an entrance pressure read. The gas pressure inside the pressure module is not immediately affected by an ambient pressure and thus serves as a sufficiently precise reference pressure. Thus, the first pressure sensor is configured to detect a depleting gas supply. The first pressure sensor may be attached to the tube upstream of the at least one valve. Thus, the first pressure sensor may be configured to measure a pressure in the gas that is supplied to the at least one valve.

Based on the pressure in the gas downstream of the at least one valve and its actuation, the pressure in the gas downstream of the at least one valve it adjusted. The pressure in the gas downstream of the at least one valve to a flow restriction defines the maximum flow of the gas that can be achieved downstream.

The pressure in the gas upstream of the at least one valve may be construed as an inlet manifold pressure of the tube. For the pressure of the gas upstream of the at least one valve, a simple measurement is sufficient. Thus, the first sensor may have an increased measuring inaccuracy. Such a simple sensor is cost-effective and is still sufficient to indicate if there is a sufficient supply pressure for the gas. That allows for implementing a warning when the supply pressure of the gas falls below a critical threshold or other features recognizing or predicting failures rooted in the gas supply system.

Furthermore, since information based on internal sensors such as the first pressure sensor is always available, it may be used for operational procedures supporting reliable operation e.g. shut down or startup procedures.

Due to the integration of the first pressure sensor into the pressure module significant efforts for integration, engineering and measures to achieve compatibility for external sensors are avoided. With such a first pressure sensor, the reliable and cost-effective operation of the claimed gas analyzer is facilitated.

Alternatively or additionally, the at least one sensor may comprise a temperature sensor. The temperature sensor is accommodated in the pressure module and is configured to measure a temperature there. The measured temperature is used as an input for a compensation function that is a part of a control program that operates the at least one valve. Based on that, the actuation of the at least one valve is adapted to adjust for thermal effects which affect the at least one sensor, e.g. the first pressure sensor, and/or the at least one valve. Furthermore, the pressure module may comprise of a memory with a calibration data field for at least one of the sensors, especially the second pressure sensor, which allows for such a compensation function. Additionally, pressure variations may be compensated, too. Thus, the gas flow through the at least one valve may be precisely adjusted for a subsequent chromatographic analysis. Furthermore, the claimed gas chromatograph allows for omitting a thermal condition control in the pressure module. As a result, the claimed gas analyzer does not need any temperature stabilizing means and/or pressure stabilizing means which allows for a simple and cost-effective design and reliable operation.

Furthermore, the intrinsic safety barrier circuit comprises connectors for at least one, preferably at least four, more preferably at least six, further preferably, at least eight channels. Each channel is utilized to control a valve that governs the gas flow through a separate tube. That allows for supplying multiple doses of gas as a carrier gas or other supply gases, which may each be used for a parallel chromatographic analysis or complex analytical solutions and combinations. The control functions of multiple channels may be concentrated in a single master control circuit. Among others, the invention is based on the surprising finding that a single master control circuit may provide sufficient power for multiple valves and sensors. The more channels the gas chromatograph encompasses, the more complex chromatographic analysis may be performed. The claimed invention allows for increasing the versatility of a gas chromatograph without unduly increasing its dimensions while maintaining an increased safety level.

In another embodiment of the present invention, the intrinsic safety barrier circuit is configured to operate at a temperature of at least <NUM>° C. The separation of the master control circuit from the at least one valve and the at least one sensor through the intrinsic safety barrier circuit allows for the use of more robust components for the intrinsic safety barrier circuit. Furthermore, the control program that encompasses the compensation for thermal effects on the tube has theoretically no operational limit. Thus, the claimed gas chromatograph can also be operated at increased temperatures. That in turn allows for limiting or even omitting temperature stabilizing means in the claimed gas analyzer.

In yet another embodiment of the claimed gas analyzer, the master control circuit is configured to provide at least <NUM> W of power. Preferable the control circuit may be configured to provide at least <NUM> W of power. Such power levels provide sufficient power for multiple valves and sensors in the pressure module or modules which may be operated simultaneously. Therefore, the claimed gas analyzer shows an enhanced degree of versatility and is suitable for further improvements or extensions.

The claimed gas analyzer may also comprise a second pressure sensor as one of the at least one sensor. The second pressure sensor is configured to measure a pressure in the tube which transports the gas. Moreover, the second pressure sensor is located downstream of the at least one valve. Since the second pressure sensor is located downstream of the at least one valve, it is not subjected to pressure fluctuations in the inlet manifold pressure. The second pressure sensor is configured to be a part of a closed control loop with the at least one valve.

As the at least one valve is not subjected to pressure fluctuations in the inlet manifold, a closed control loop function of the closed control loop may omit any compensating functions for that and is able to obtain an increased precision. Furthermore, the second pressure sensor may be configured to be connected to a calibrated reference as a reference pressure. The reference pressure may be provided by a pressurized container. Compared to an ambient pressure as a reference pressure like atmosphere pressure, the calibrated reference is robust against fluctuations of ambient air pressure. Such fluctuations may occur when the gas analyzer is accommodated in a shelter, especially one with a purging system. Moreover, such fluctuations may be caused by an effluent collection system that is to carry away potential exhaust fluids from the gas analyzer, e.g. processed sample and carrier gas. Using such a calibrated reference pressure stabilizes the operation of the claimed gas analyzer and allows for reliably yielding exact measurements. The claimed gas analyzer offers an improved level of precision and is robust against unfavorable ambient conditions at the same time.

In another embodiment of the present invention, the second pressure sensor has a higher precision than the first pressure sensor. In that context, a higher precision is to be construed as having a smaller measurement error. The second pressure sensor may be a pressure sensor with a measurement error on the order of 100ppm, whereas the first pressure sensor may be a pressure sensor with a measurement error of up to <NUM> percent. Due to that, the first pressure sensor may be embodied as a simple and cost-efficient pressure sensor which serves for sensing the inlet manifold of the pressure module and thus emulating a fixed pressure switch. In turn, the second pressure sensor is substantially insulated from pressure fluctuations in the inlet manifold and is capable to perform a pressure measurement with an increased precision. Complex compensating means for pressure fluctuations may be omitted in the second pressure sensor. Thus, the present invention utilizes the first and second pressure sensor in more appropriate manners and is also cost-effective.

The object outlined above is also achieved by the claimed method for simulating the operational behavior of a gas analyzer. In context with the claimed method, the terms "gas analyzer" and "simulated gas analyzer" may be construed as being interchangeable. The operational behavior may comprise the progression of thermodynamic variables of a gas transported through it, e.g. its temperature, density, pressure, heat energy and/or enthalpy. It may also comprise it combustion behavior, i.e. the ignition behavior of the gas, its burn rate, its volume expansion, its released heat energy and/or enthalpy. The method comprises a first step during which a set of data points is provided. The set of data points mirror the functioning of at least a portion of the gas analyzer that is to be simulated. The data points may mirror the design of the respective portion of the gas analyzer or the entire gas analyzer. Particularly, the set of data points may constitute a so-called digital twin or may be part of a digital twin. The expression digital twin is to be construed in accordance with the document <CIT>. The set of data points may be provided by loading them into a memory of a computer on which the claimed method may be performed.

The claimed method also comprises a second step in which at least one operational parameter of the gas analyzer is set. The operational parameter may comprise a condition under which the gas analyzer is operated, e.g. an ambient temperature. Additionally or alternatively, the operational parameter may comprise an information about the analysis process that is to be simulated, e.g. which gas or gasses and in which amounts are to be utilized, the pressures, temperatures and/or flow rates at which the gas or the gasses are provided, and/or the duration of the operation. The second step may be performed by a user and/or through a data interface.

In addition to that, the claimed method comprises a third step in which a computer program product is executed. That computer program product is configured to emulate the operational behavior of the gas analyzer based on the set of data points provided in the first step. The operational behavior is also emulated based on the at least one operational parameter provided in the second step. The set of data points and the operational parameter may be combined by the computer program product which emulates the operation, i.e. the operational behavior, of the gas analyzer under the circumstances defined in the first and second step. That emulated operation is also to be construed as a simulated operation. That serves for determining at least one performance parameter of the gas analyzer. The performance parameter describes an information about events during the simulated operation which are yielded through the simulated operation of the simulated gas analyzer. For example, the performance parameter may comprise thermodynamic quantities like the temperature, density and/or flow rate of a gas that exits a component of the simulated gas analyzer and/or an information about the composition of a gas mixture inside a component of the simulated gas analyzer. The performance parameter may also comprise an information, if a gas mixture has ignited during the simulated operation, under which conditions that ignition took place and/or an information about a pressure increase caused by that ignition.

In a fourth step, the at least one performance parameter is output to a user and/or a data interface. The fourth step may utilize a suitable data connection to an output device readable by the user and/or to a different computer platform that may be configured to process the at least one performance parameter further. According to the present invention, the gas analyzer simulated through the claimed method is a gas analyzer according to one of the embodiments outlined above. The features of the claimed gas analyzer also apply to the claimed method in a corresponding manner. Thus, the features of the claimed gas analyzer also confer to the claimed method.

The claimed gas analyzer shows an increased level of safety since, among other reasons as well, its master control circuit is separated from it pressure module. Complex combustion calculations which include ignitions through sparks and the like may be omitted. Instead, the claimed method may only take into consideration self-ignition conditions for the gas or the mixture of gasses present in the pressure module. Particularly, the third step may be performed without to take into account ignitions by sparks and the like. That in turn allows for a significant simplification of the simulation performed based on the claimed method. Therefore, the claimed method allows for an accelerated simulation of the operational behavior of a gas analyzer which may be performed on a relatively simple hardware platform with limited a computing capacity. With the claimed method, intended operations of a physical gas analyzer, that is as least partly mirrored by the set of data points, may be optimized faster. Particularly, a more comprehensive set of simulations may be performed in a reduced amount of time. Since the claimed gas analyzer also shows an improved aptitude for its own simulation, it may be operated in an efficient manner.

The object described in the present application is also achieved through the claimed computer program product. The claimed computer program product is configured to simulate an operational behavior of a gas analyzer. Consequently, the computer program product may comprise code and/or instruction that make a computer perform the simulation of the operational behavior of the gas analyzer. According to the present invention, the operational behavior is simulated through a method according to one of the embodiments described above. The computer program product may comprise a set of data points that at least partly mirror the gas analyzer that is to be simulated. The computer program product may be a so-called digital twin, as it is described in <CIT>. Furthermore, the computer program product may be stored in a machine-readable medium that is configured to interact with a computer. The claimed computer program product may be embodied as software or in a hardwired form, e.g. a chip, an ASIC or an FPGA, or as a combination of software and a hardwired form. Furthermore, the computer program product may be embodied as a monolithic program that is executed on a single hardware platform. Alternatively, the computer program product may be embodied as a modular software, comprising partial programs that are executed on separate hardware platforms and which interact with each other over a suitable data connection, e.g. an ethernet connection, an internet connection or a mobile data service.

In the following, the present invention will be described in more detail in several figures. The figures are to be construed as mutually complementary. Particularly, identical numerals are to be construed as having the same technical meaning. The features of the embodiments shown in the figures may be combined with each other. Additionally, the features of the embodiments shown in the figures may also be combined with the embodiments outlined above. In particular, the figures show:.

<FIG> shows a carrier gas supply unit <NUM> that is utilized in a first embodiment of the claimed gas analyzer <NUM>. The carrier gas supply unit <NUM> comprises a gas reservoir <NUM>, that supplies a gas <NUM>, e.g. hydrogen, that is to be fed to a separation column <NUM>, that is not shown in detail. The gas <NUM> from the gas reservoir <NUM> is fed through pressure regulating means <NUM> and into a pressure module <NUM>, which encloses an upstream portion <NUM> of a pipe <NUM>. The upstream portion <NUM> of the pipe <NUM> is connected to a fitting <NUM>. The gas <NUM> in the upstream portion <NUM> of the pipe <NUM> is subjected to an upstream pressure <NUM>, that is to be construed as an inlet manifold pressure. The upstream portion <NUM> of the pipe <NUM> is connected to a valve <NUM> which is potted in an encapsulation <NUM>. The encapsulation <NUM> may be made of a resin, a thermoplastic material or any other castable material that is fit to provide an exclusion of the gas <NUM>. The valve <NUM> comprises a valve portion <NUM> that constitutes a barrier between the upstream portion <NUM> of the pipe <NUM> and a downstream portion <NUM> of the pipe <NUM>. That barrier may be actuated, i.e. opened or closed, through a solenoid portion <NUM> of the valve <NUM>. The actuation of the solenoid portion <NUM> and therefore the valve <NUM> is controlled through a valve circuit <NUM> that is also potted in the encapsulation <NUM>. Since the solenoid portion <NUM> may store a significant amount of energy that is capable of ignition, the encapsulation <NUM> prevents the gas <NUM> in the pressure module <NUM> from getting to the solenoid portion <NUM>, especially if the gas <NUM> is hydrogen. Thus, the encapsulation <NUM> constitutes a protection means against explosions and increases the overall safety of the carrier gas supply unit <NUM> and the gas analyzer <NUM>.

The downstream portion <NUM> of the pipe <NUM> discharges into the separation column <NUM> that is not shown in detail in <FIG>. In the downstream portion <NUM> of the pipe <NUM> the gas <NUM> is subjected to a downstream pressure <NUM> that is regulated through the valve <NUM> and determines the pressure at which the gas <NUM> flows into the separation column <NUM>. To that end, the pressure module <NUM> encompasses two sensors <NUM> that are embodied as pressure sensors <NUM>, <NUM>. A first pressure sensor <NUM> is connected to the upstream portion <NUM> of the pipe <NUM> and is configured to measure the upstream pressure <NUM>. The first pressure sensor <NUM> utilizes a gas pressure <NUM> inside the pressure module <NUM> as a reference pressure. Based on measurements by the first pressure sensor <NUM>, the gas analyzer <NUM> is configured to detect a receding upstream pressure <NUM> and to indicate that the depleting gas reservoir <NUM> is to be replaced.

The valve <NUM> substantially shields the downstream portion <NUM> of the pipe <NUM> from fluctuations in the upstream pressure <NUM>, which is to be construed as the inlet manifold pressure. During a normal operation of the carrier gas supply unit <NUM> the valve <NUM> is actuated to adjust the downstream pressure <NUM> to a predefined level. To that end, the downstream portion <NUM> of the pipe <NUM> is equipped with the second pressure sensor <NUM> that is arranged to measure the downstream pressure <NUM>. The valve <NUM>, the valve circuit <NUM> and the second pressure sensor <NUM> are configured to form a closed control loop that regulates the downstream pressure <NUM>. Moreover, the second pressure sensor <NUM> is connected to a calibrated reference pressure <NUM>. Utilizing such a calibrated reference pressure <NUM> allows for an even more precise adjustment of the downstream pressure <NUM>. Particularly, such a calibrated reference pressure <NUM> is robust against fluctuations of an ambient pressure. Furthermore, the carrier gas supply unit <NUM> according to <FIG> may be combined with a purging system and/or an effluent collection system without compromising the obtainable measurement precision.

The second pressure sensor <NUM> has a higher precision than the first pressure sensor <NUM>. Thus, the second pressure sensor <NUM> is apt to adjust the downstream pressure <NUM> at an increased precision. The function of the first pressure sensor <NUM> does not require such a level of precision and is therefore a relatively simple and cost-effective sensor <NUM>. The first and second pressure sensor <NUM>, <NUM> are appropriately chosen for their respective functions.

The valve circuit <NUM> is connected to a control interface <NUM> that is configured to establish a connection to a control unit <NUM>. The control unit <NUM> encompasses a control enclosure <NUM> in which a master control circuit <NUM> is accommodated. The control enclosure <NUM> is self-contained and separate from the pressure module <NUM>. Substantially any exchange of fluids between the respective inside of the control enclosure <NUM> and the pressure module <NUM> is inhibited. The master control circuit <NUM> is connected to an intrinsic safety barrier circuit <NUM> that serves as an interface to the control interface <NUM> of the pressure module <NUM>. Both power and signals <NUM> are being transferred between the control unit <NUM> and the pressure module <NUM> through the intrinsic safety barrier circuit <NUM>. In particular, that power and these signals <NUM> allow for actuating to valve <NUM> and communication with the sensors <NUM>, which comprise the first and second pressure sensor <NUM>, <NUM>. The intrinsic safety barrier circuit <NUM> comprises multiple electronic components which are configured to limit a voltage supplied to the control interface <NUM>.

The energy supplied to the control interface <NUM> is limited to a maximum energy that does not allow for ignition inside the pressure module <NUM> or valve <NUM>. Even if gas <NUM>, especially hydrogen, leaks into pressure module20, there will be insufficient energy to cause an ignition. The claimed gas analyzer <NUM> is apt for using flammable gases like hydrogen as a carrier gas <NUM> for operation. Furthermore, at least a portion of the gas analyzer <NUM> shown in <FIG> is mirrored in a set of data points <NUM> which belong to a computer program product <NUM>. The computer program product <NUM> is a digital twin <NUM> of at least a portion of the gas analyzer <NUM>. The computer program product <NUM> is configured to simulate the operational behavior of the gas analyzer <NUM>.

<FIG> shows an overall layout of the second embodiment of the claimed gas analyzer <NUM> that is a gas chromatograph. The gas chromatograph comprises a carrier gas supply unit <NUM> which provides a carrier gas <NUM> for a chromatographic analysis that is to be performed with the gas analyzer <NUM>. The carrier gas <NUM> is taken from a gas reservoir <NUM> and fed through a pressure module <NUM> that is controlled through a control unit <NUM>. The gas <NUM> from the gas container <NUM>, i.e. the carrier gas <NUM>, is fed to an injector <NUM> where it is mixed with a chromatographic sample <NUM>, which is to be analyzed in the chromatographic process. The mixture of the chromatographic sample <NUM> and the carrier gas <NUM> are supplied to a separation column <NUM> which splits up the chromatographic sample <NUM> into its constituents. Since the chromatographic sample <NUM> travels with the carrier gas <NUM>, a dedicated volume of the chromatographic sample <NUM> is determined by the downstream pressure <NUM> which is regulated in the pressure module <NUM>. The constituents of the chromatographic sample <NUM> are being analyzed in a detector <NUM> which detects at least one physical property of multiple constituents of the chromatographic sample <NUM>. Signals from the detector <NUM> are amplified in an amplifier unit <NUM> and fed to a data processing unit <NUM>. Based in the amplified signals from the amplifier unit <NUM>, the data processing unit <NUM> can identify and quantify multiple constituents of the chromatographic sample <NUM>. The carrier gas supply unit <NUM> is embodied according to the carrier gas supply unit <NUM> as shown in <FIG>.

Claim 1:
Gas analyzer (<NUM>) comprising a self-contained pressure module (<NUM>) that encloses at least partly a pipe (<NUM>) for a gas (<NUM>), that is equipped with at least one sensor (<NUM>) and a valve (<NUM>) that comprises a valve portion (<NUM>) and a solenoid portion (<NUM>), said sensor (<NUM>) and said valve (<NUM>) being operable through a master control circuit (<NUM>), characterized in that said master control circuit(<NUM>) is accommodated in a self-contained control enclosure (<NUM>) that separates the master control circuit (<NUM>) from said pressure module (<NUM>) with said valve (<NUM>) and said sensor (<NUM>), the valve (<NUM>) and the sensor (<NUM>) being accommodated in the pressure module (<NUM>).