Comparison of the humidity standards at the CETIAT and the CMA

In order to compare the humidity standards at the Centre Technique des Industries Aérauliques et Thermiques (France) and the Centre for Metrology and Accreditation (Finland), a dew-point hygrometer was calibrated at both laboratories within a EUROMET project. There were eight measurement points in the range -40 °C to + 60 °C. The difference between the standards was determined and its uncertainty was evaluated. The difference was between -0.03°C and + 0.09°C with the average being 0.01°C. The uncertainty of the difference was ±0.08°C to ±0.17°C (k = 2). The measurements and the analysis of the results are reported in this paper.