Gas mass-flow meters: Measurement and uncertainties

• The GMFM measurement model and gas response factor concept.
• The model of dynamic volumetric method of dilution using GMFM.
• The model application to the calibration gas flow meters of high throughput and to uncertainty calculation.
• The calculation of enclosed large gas flow rate.

The application of gas mass-flow meters (GMFM) sensors needs the knowledge of its measurement model and measurement uncertainties. It was already known that the GMFM output model depends on gas mass-flow and gas composition. In this work, different throughput GMFM sensors were used for different gas flow rates and gas composition in order to verify and to improve the GMFM measurement model.A direct calibration procedure and a dynamic volumetric method were applied both to get the measurement model and to evaluate the performance of gas sensors and GMFM sensors against certified reference materials and suitable standards. Additionally, the obtained data were used both to calculate the uncertainties of gas mass-flow measurement and to improve the GMFM gas response factors.The calculated uncertainties of the GMFM direct measurement was approximately 2% of the measured value. The uncertainty of the dynamic volumetric method developed in this work was found as approximately 5% of the measured value and that was mainly influenced by the uncertainties of the standards used.