Abstract: A measurement method in which, at the start of a measurement chain, a measured variable is picked up and is further-processed over the course of the measurement chain by conversion to generate a measurement result, where the original or converted measured variable is modulated at a predetermined modulation frequency at a first point in the measurement chain. At a second point in the measurement chain or sequence, which is after the first point in the direction of further-processing, a variable is added to the converted measured variable. The measurement chain or sequence is calibrated using different known values for the measured variable, where different vectors are obtained that define a characteristic, and an unknown value for the measured variable is determined from that point of the characteristic at which the vector obtained in the process or its extension intersects the characteristic.

Abstract: The invention relates to a NDIR two beam gas analyser in which infrared radiation is guided by modulation in an alternating manner through a measuring chamber and a reference chamber and is subsequently detected, a measurement signal being produced due to the analysis which determines the concentration of a measurement gas component present in the measurement chamber.

Abstract: The invention relates to a NDIR-gas analyser comprising an infrared radiation source (1), a measuring vessel (3) containing a gas mixture (4) having a measuring gas component (5) that is to be detected, and a detector device (7) that is arranged behind the measuring vessel that can detect the influence of ageing of the radiation source (1) and optionally dirt deposits in the optical radiation path without interrupting measuring. According to the invention, at least one optopneumatic detector (15) is arranged in the beam path of the radiation source (1), said detector being filled with any gas (16) when arranged between the radiation source (1) and the measuring vessel (3).

Abstract: The invention relates to a NDIR-gas analyser comprising an infrared radiation source (1), a measuring vessel (3) containing a gas mixture (4) having a measuring gas component (5) that is to be detected, and a detector device (7) that is arranged behind the measuring vessel that can detect the influence of ageing of the radiation source (1) and optionally dirt deposits in the optical radiation path without interrupting measuring. According to the invention, at least one optopneumatic detector (15) is arranged in the beam path of the radiation source (1), said detector being filled with any gas (16) when arranged between the radiation source (1) and the measuring vessel (3).