Bezgachnyuk Y. Improved methods and apparatus to ensure traceability of measurements of volume and volumetric gas flowrate

The thesis is devoted to the solution of scientific and applied problems of traceability of measurement of gas volume and volumetric flowrate through improved methods, devices, and development of the normative base to ensure traceability of measurement unit to working gas flow measuring devices used for the account of natural gas from the state primary standard. The theoretical and experimental studies of critical nozzles for use as transfer standards were carried out. The numerical simulation of influence of the pressure ratio on the critical nozzle discharge coefficient. Improved algorithm to calculate geometrical dimensions of the critical nozzle. The method of traceability in the range of flowrates below the minimum reproducible by state primary standard of unit of volume and gas flowrate using a parallel connection of critical nozzles. A chain of traceability of measurements from the state primary standard of unit of volume and volumetric gas flowrate to the working measuring instruments was developed. Developed and implemented in Ukraine metrological practice regulations governing the methods of calibration to ensure traceability of measurements.