Calibrating twin-jet laboratory gas analysis cuvette

摘要

In a twin-jet gas analysis assembly and process for calibration of the same: (a) a jet (4) of the measured gas passes through a first measuring cuvette (6) which may be filled with the gas (10) being measured; (b) a jet of comparative gas (5) passes through a second comparative cuvette (13) filled with a comparative gas; (c) a detector arrangement (14-17) is located downflow from the measuring cuvette (6) and comparative cuvette (13), generating a differential signal (DS) from the jets (4, 5) emerging from the two cuvettes (6, 13); (d) a signal processing assembly (19) generates a measured vale (MW) by weighting the differential signals (DS) with a weighting factor (K1); the weighting factor (K1) is set when filling the cuvette (6) with a calibration or standard gas (12), such that the measured value (MW) is the same as that of the calibration or standard gas (12). The novelty is that: (e) if the cuvette (6) is not filled, or is filled with an inert gas, and the jet is interrupted, a supplementary factor (K2) is determined, such that the differential signal (DS) is the same as that of the calibration value when weighting with the factor K1 and supplementary factor K2; (f) in latter calibration processes using a measuring unfilled cuvette (6), or one filled with an inert gas (11), that the differential signal (DS) null-point deviation is established, and when the comparative jet (5) is interrupted, the weighting factor (K1) is so corrected that the differential signal (DS) is the same as the calibration value when weighting with the correction factor (K1) and the supplementary factor (K2); and (g) when analysing the gas under measurement, that the null point deviation established is subtracted as the offset value (DSO) from the differential signal (DS).