Intercomparison of vacuum standards between the Physikalisch Technische Bundesanstalt (Germany) and the National Physical Laboratory (India) using two spinning rotor gauges

Abstract

The paper describes the results of a comparison of low‐pressure standards maintained at the National Physical Laboratory (NPL, India) and the Physikalisch Technische Bundesanstalt (PTB, FRG) over the range 10−3–2 Pa. The intercomparison was carried out by employing spinning rotor gauges shipped with a novel transport device. Both the laboratories, i.e., NPL and PTB, use static expansion systems for pressure generation. The gauge coefficients σ0,eff of the two gauges for Ar agree within ±0.5% for the two laboratories. This result proves agreement of the respective national standards in the above range of pressures. The small deviation of −0.4% between calibrations over a period of one year before and after air‐parcel transportation from Berlin to New Delhi and back is indicative of a careful handling of the rotors during operation and a good performance of the employed transport device.