Establishing the International Acceptability of Fluid Quantity and Flow Rate Measurements (Invited Paper)

Rapid advances in technology-communications, the internet, tele-marketing, travel, etc. are accelerating the globalization of the world’s market places. To facilitate this globalization by eliminating measurement-based barriers to trade, the International Committee on Weights and Measures (CIPM) has, in accord with the authority granted it by the International Treaty of the Meter, produced a Mutual Recognition Arrangement (MRA). This MRA, signed into existence in Oct 1999, has the objectives: 1. to establish the degree of equivalence of national measurement standards maintained by the National Metrology Institutes (NMIs) that have signed the MRA, 2. to provide for the mutual recognition of calibration and measurement certificates issued by the NMIs, and thereby 3. to provide governments and other parties with a secure technical foundation for wider agreements regarding measurements that relate to international trade, commerce, and regulatory affairs. Information on the CIPM, and the MRA can be found on the website: http://www.bipm.org/. Degrees of equivalence between and among national measurement standards are based on the results of Key Comparisons (KCs) conducted within the Consultative Committees of the CIPM. Flow measurement efforts are being addressed by the newly formed Working Group for Fluid Flow (WGFF) of the CIPM Consultative Committee on Mass and Related Quantities (CCM). The WGFF efforts are organized into six, specific measurement areas: water, hydrocarbon liquid, air speed, liquid volume, high pressure gas, and low pressure gas flow. In each of these areas, and according to MRA rules, the efforts are to design and conduct KCs that quantify the equivalence of the flow standards maintained in the participating NMIs. To determine appropriate operating ranges for KC’s, the WGFF is reviewing the Calibration and Measurement Capabilities (CMCs) of the participating NMIs. This presentation will briefly describe the MRA and the current WGFF plans and programs to conduct the KC tests. Specific techniques planned for the KCs will be to design flow meter transfer standards comprised of tandem arrangements of flow meters that are tested in the selected fluid and flow conditions to quantify the performance of NMI flow standards under actual conditions of use. Statistically sufficient and metrologically sound test protocols are being devised to efficiently and effectively produce the required data bases. Youden graphical analysis of variance and other statistical techniques are planned to analyze the resulting data. The results of these WGFF efforts are expected to make it feasible for flow measurements made anywhere in the world to be understood and acceptable anywhere else.