High vacuum measured by the spinning rotor gauge: Status report of the Bureau International des Poids et Mesures intercomparison

The spinning rotor gauge is used as a transfer gauge in an international intercomparison of vacuum pressures in the range 5×10⁻⁴ to 1 Pa. Results for the stability of the transfer gauge as well as for the vacuum standards in the various laboratories are now available. Several years of experience prove the high stability of this type of gauge; calibrations against a primary pressure standard yield long‐term reproducibility within ±0.5%. However, experience also reveals that improper handling of the rotor balls may cause irreversible changes by as much as several percent. In the intercomparison the majority of participating laboratories have performed calibrations so far. Most data lie within an interval of ±1% and never deviate by more than ±3% from the mean. Thus the international standard of high vacuum pressures is very reasonable.