| Zugriffsnummer | 18599 |
| Dokumenttyp | Bericht |
| Sprache | Englisch |
| Titel | The treatment of uncertainties of calibration pressures in vacuum : EUROMET project 323 ; final report |
| Autor(in); Institution |
Bergoglio, M.; Istituto di Metrologia Gustavo Colonnetti (IMGC), Torino, ITALY
Calcatelli, A.; Istituto di Metrologia Gustavo Colonnetti (IMGC), Torino, ITALY
Jousten, Karl; 7.23, Vakuummetrologie, PTB-Berlin
Redgrave, F.; National Physical Laboratory, Teddington, UK
|
| Quelle/Jahr | (1997), 32 Bl. |
| Schriftenreihe | IMGC technical report: 7 |
| Verlag | Torino: IMGC |
| Zusammenfassung | The present work was intended to find an agreement between the primary laboratories on the calculation of the uncertainties and the various correction factors associated with the calculation of the pressures generated by the laboratories' primary standards. Each laboratory has its own system and procedure which can make it difficult to identify a common way of evaluation. The most difficult part of the project was to define which parameters are correlated and the level of correlation, particularly for the static expansion method. For this method of pressure generation two possible solutions are considered: 1) the measurement of the expansion ratio is considered in connection with the generated pressure, so that all the factors are considered together with their correlation. 2) the measurement of the expansion ratio (and its uncertainty) is a special experiment which may be considered independently from the calibrations. The equation for the calibration pressure is therefore considered independently from the expansion ratio and is regarded as uncorrelated with the calibration pressure. Similarly for the continous expansion method it is also difficult to define the level of correlation between the influence quantities as this depends on the different practical realistain of the standards; the conductance of the orifice and gas flow rate may or may not be correlated depending on whether the conductance is measured or calculated from the geometry. The co-operation in the project has been useful for clarifying the procedures and calculations. |
