Metrologisen jäljitettävyyden kehittäminen paine- ja monisuuremittauksissa: Yhtenäinen lähestymistapa staattisiin, dynaamisiin ja digitaalisiin kalibrointiprosesseihin

Metrological traceability is fundamental to ensuring the reliability and comparability of measurements in science and industry. As measurement environments become increasingly complex—requiring multi-parameter monitoring, dynamic process control, and digital data integration—traditional calibration methods and traceability chains face new challenges. This thesis presents a unified framework to enhance metrological traceability across static, dynamic, and multi-quantity measurement systems, integrating advanced calibration methods, robust reference standards, and digital documentation. The research in this thesis establishes the realization of the primary measurement standard for pressure directly using SI base units, by determining the effective area of pressure balance piston-cylinder units through high-accuracy dimensional measurements. This approach anchors pressure measurements and calibrations to the fundamental SI quantities – mass, length, and time – ensuring international compatibility and long-term stability. A calibration facility was developed for simultaneous calibration of pressure, temperature, and humidity devices, improving calibration representativeness and enabling investigation of cross-influences between quantities. For dynamic pressure measurements, the thesis advances calibration standards, extending traceable calibration ranges and enabling calibrations under realistic, application-relevant conditions. Furthermore, the work introduces an evaporation-based dynamic generation method for traceable calibration gases, addressing the challenges of reactive compounds where traditional bottled standards are inadequate. An important aspect of this thesis is the comprehensive estimation of measurement uncertainty for the generated reference gases. The uncertainty analysis follows the principles of the Guide to the Expression of Uncertainty in Measurement (GUM), ensuring the reliability and metrological traceability of the generated calibration gases. The thesis also demonstrates the practical realization of metrological traceability in digital format through the implementation of Digital Calibration Certificates (DCCs), supporting secure, automated, and interoperable calibration data exchange. The results form a comprehensive framework that enhances the reliability, efficiency, and scalability of metrological traceability, supporting the evolving requirements of scientific research, industrial innovation, and regulatory compliance in the digital era.