Intercomparison of vacuum standards between LIP and PTB

Abstract The Lanzhou Institute of Physics (LIP) with the McLeod gage and the Physikaalisch-Technische Bundesanstalt (PTB) with the static expansion standard, adopting the DL-2 hot cathode ion gage made in China as the transfer gage, twice carried out intercomparisons for He, Ar and N 2 from 1987 to 1989, respectively. The deviation of the results was well within the range of uncertainties. During the two years, the reproducibilities of the DL-2 were 0.49% for the PTB and 0.88% for the LIP. The LIP purchased a SR-G gage calibrated by the PTB from MKS Co. When transported to China, the LIP conducted the careful calibration of it. The deviation of the data from the PTB and LIP was also within the range of uncertainties.