BS ISO 12963:2017 pdf download – Gas analysis Comparison methods for the determination of the composition of gas mixtures based on one- and two-point calibration

BS ISO 12963:2017 pdf download – Gas analysis Comparison methods for the determination of the composition of gas mixtures based on one- and two-point calibration 6 Principle 6.1 General requirements The composition of a gas mixture is determined by separate measurement of the amount fraction of every specified componen t. “Separate” implies that the response obtained for the component of interest is treated independently of any other response obtained for any other componen t. It does not impede obtaining several responses for several components in the same instrument run. Therefore , the procedure for determining the amount fraction of only one specified component is described. Possible interferences of other components on the measurement ofthe component ofinterest shall be avoided or corrected for separately. This subject is not further addressed in this document. The procedure for determining the amount fraction X of a specified component X in a sample of a gas mixture , or in a series of such samples , is performed in a sequence of steps as summarized below. a) Specify the analytical range of interest , R , i. e. the range of the amount fraction x to be determined , and the acceptable or required (if applicable) uncertainty level b) Specify the analytical method and the measuring system to be used: 1) calibration range (to encompass the analytical range); 2) composition , including uncertainty , of the calibration gas mixtures; 3) parameters of the analytica l method; 4) measuring conditions; 5) number and sequence of calibration measurements c) Select,from the list given in 6.2, an approach for calibration and determining the amount fractions of components in unknown samples in the regular, i.e. daily mode when one- and two-point basedanalysis functions are used. d) For the relevant ranges of responses and component amount fractions, determine the uncertainty level of the prospective results based on the analysis function. If the result is acceptable,performance evaluation was successful. For the calculation of the measurement uncertainty of results obtained in the regular calibrationmode, an estimate u(4) for the contribution of possible nonlinearity of the system is needed. Thisestimate is calculated in a performance evaluation of the system according to Clause 8and Annex C.The evaluation is best done after the specifications according to a) to c) are set. The estimate isused in all subsequent regular calibrations until there is reason to assume significant changes inthe instrument performance. The main reasons for such...