Siemens Aktiengesellschaft

Frank Probst

Udo Gellert

Piotr Strauch

Thomas Hankiewicz

Daniel Depenheuer

Josef Richter

A method in which the wavelength of the light of a tunable light source is varied periodically over an absorption line of interest for the gas component to measure the concentration of a gas component in a measurement gas based on one of two measurement methods of direct absorption spectroscopy and wavelength modulation spectroscopy and, where in the case of wavelength modulation spectroscopy, the wavelength of the light is additionally sinusoidally modulated at a high frequency and with a small amplitude, where the intensity of the light is detected after transradiation of the measurement gas and processed to yield a measurement result, and where in order to increase the accuracy and reliability of the measurement, the two measurement methods are applied simultaneously during each period, or alternately in consecutive periods, and their results are combined by averaging to form the measurement result.

Method for measuring concentration of a gas component in a measurement gas

Low-complexity, application-independent fixation of a chromatogram is achieved by a) determining a limit frequency under the assumption that the shape of the peaks in the chromatogram corresponds approximately to a Gaussian function having a standard deviation and the Fourier transform of the Gaussian function describes the frequency spectrum of a peak, at which limit frequency the Fourier transform has decreased to a predetermined limit value, b) determining the height, width, and retention time of each individual peak from the chromatogram, or a chromatogram taken previously under the same conditions, c) determining a constant factor based on a first predetermined relationship, d) determining the functional dependency of the limit frequency on the retention time as a variable quantity based on a second predetermined relationship, and e) filtering the chromatogram with the limit frequency depending on the retention time as the variable quantity using a low-pass filter.

Method for filtering a chromatogram

A measurement arrangement includes four electrically heated resistors which are arranged in gas paths and are connected to form a Wheatstone bridge, where each of two resistors which are diagonally opposite each other in the Wheatstone bridge are contained in a respective component arranged on a common heated carrier, each respective component is assigned to one heating resistor arranged near the component on the carrier, and where an unbalanced state of the Wheatstone bridge is compensated for by variably energizing the heating resistors.

Measurement arrangement having electrically heated resistors arranged in gas paths

The invention relates to a gas sample to be analyzed, wherein said sample is guided by means of a carrier gas through a separator unit having a downstream thermal conductivity detector providing a chromatogram having peaks for different analytes as a measurement signal. When using a thermal conductivity detector having a heated gold thread coated with a parylene F, hydrogen is used as a carrier gas, and a peak for the analyte hydrogen sulfide is generated by differentiating the chromatogram at the location of said analyte. The invention permits unlimited use of hydrogen as a carrier gas, even if the analyte is oxygen.

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Herxheim Bei Landau/Pfalz, Germany

Frank Probst