Abstract: The invention relates to a method of determining mainly the compressibility number K, the standard volumetric gross calorific value Hv,n and the standard density ?n of test gases using values determined from a spectrum of the test gases. The invention describes various approaches of translating the values for determining the desired values using the data of the spectrum in the operational condition to the standard reference condition using two-step iteration processes without having to subject the test gases to time-consuming treatments. The invention further relates to devices for determining the values required for the methods and which further develop devices for carrying out the methods.

Abstract: A procedure for the determination of the quality of gas of a probe gas, in particular a burnable gas, using a transmission spectrum of the probe gas determined at operating conditions by means of spectroscopical methods of measurement. At least the associated values of the pressure p and the temperature T of the probe gas are determined and in a number of selected spectral regions at least one spectral vector is constituted by integrating quantities of the transmission spectrum of the probe gas, which shows as components the values of the integrals with respect to the selected spectral regions and is characteristic for the properties of the probe gas at operating conditions.