Improved method for pressure measurement in saturation chamber of primary dew/frost point generators

In the old method, the precise digital barometer is used for determination of saturated air pressure inside the saturation chamber. The barometer is traceable to the pressure balance, which is used as a national standard for pressure in Croatia. In the new method, the pressure was maintained directly by the primary pressure balance, achieving this way the significant improvement of related measurement uncertainties for both, pressure measurement and the dew/frost point realization. The paper will give a detailed description of both measurement setups as well as corresponding measurement uncertainty analyses. During the experiments it was also observed that in the second setup, balance stabilized the pressure oscillations as well as oscillations of the dew-point temperature measured by the chilled mirror hygrometer under calibration, making indirect improvement of related measurement uncertainties.