Study of metrological characteristics of household gas meters when measuring the volume flow rate of gas-hydrogen mixtures

The paper presents the results of studies of the influence of pure gaseous hydrogen and gas-hydrogen mixtures and the performance and metrological characteristics of membrane-type gas meters used in the household sector. For the study, membrane-type meters of leading domestic and European manufacturers were pre-selected. A series of static and dynamic tests were conducted for the meters. The static tests involved checking the air-tightness of the meters under the influence of gaseous mixtures. The dynamic tests involved measurements on a simulated test site with a work medium of pure hydrogen as well as hydrogen-methane mixtures. The proportions of the mixtures used were: 80% of methane and 20% of hydrogen, and 90% of methane and 10% of hydrogen respectively. A structural diagram of the measuring system was developed. The measurements were performed by comparing the volume of the gas that passed through the experimental meter with the volume measured by the reference meter. The measuring system was equipped with a means for measuring the pressure and temperature of the measuring medium to bring the results of the experiments to standard conditions. As a reference means in the assembled measuring system, a drum-type gas meter with a calibration characteristic pre-determined under laboratory conditions with a work air medium was used. After the experimental studies with the work hydrogen medium and hydrogen gas mixtures under the conditions of the test site, the metrological characteristics were re-determined under laboratory conditions for the reference meter. To conduct the experiments with the maximum possible accuracy and to exclude the influence of additional errors on the measurement result, a specialized software was developed to automate the measurements of the volume of the gas passing through the reference meter, measuring the pressure and temperature of the work medium and fixing the required value of the gas volume flow rate. The results of the experiments for several meters are presented in the form of tabular values and graphs. General conclusions were made regarding the influence of hydrogen and gas-hydrogen mixtures on the change in metrological characteristics of household gas meters.