The article considers the current methods of measuring the calorific value of natural gas which are valid in the upto-date gasometry. The procedure for measuring the gross and net volume-basis specific calorific value of natural gas by the calorimetric method is analyzed. It is shown that to increase the accuracy and validity of measurement results, the experiment to determine the values of gross and net volume-basis specific calorific should be performed for at least 5 samples of the investigated gas. A methodology for estimating the accuracy of measuring the gross and net volume-basis specific calorific values of natural gas by the calorimetric method by finding estimates of the uncertainty of the obtained measurement results taking into account both random and systematic influencing factors are developed. The uncertainty budgets for measuring the gross and net volumebasis-specific calorific values of natural gas have been developed for the practical implementation of the methodology. The results of experimental studies of samples of one of the natural gas fields are given and the objective values of the gross and net volumebasis specific calorific with estimates of extended uncertainty are obtained.
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