Open AccessEstablishment of Thailand’s national primary vacuum standard by a static expansion method
Author(s) -
S. Phanakulwijit,
J. Pitakarnnop
Publication year - 2019
Publication title -
journal of physics. conference series
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.21
H-Index - 85
eISSN - 1742-6596
pISSN - 1742-6588
DOI - 10.1088/1742-6596/1380/1/012003
Subject(s) - calibration , metrology , pressure measurement , expansion ratio , range (aeronautics) , materials science , physics , analytical chemistry (journal) , composite material , optics , chemistry , thermodynamics , chromatography , quantum mechanics
A novel primary standard system for a vacuum pressure calibration has been established at the National Institute of Metrology, Thailand (NIMT). The system, which cover the pressure range from 1.3 • 10 -1 Pa up to 1.3 • 10 3 Pa is based on the static expansion method. By the series of re-expansion, the range could be extended to lower calibration pressures. The facility consists of two small and one large vessels, which provide an expansion ratio by a factor of approximately 10 2 to 10 3 for a single expansion and more for a multiple one. Six platinum resistance thermometers are attached to the vessel to ensure the correction of the non-isothermal effect during an expansion. The system could deliver the expanded (k = 2) relative uncertainties under 0.6% of reading at the lowest operating pressure. The measurement results of the system were verified by comparing with the calibration results of the capacitance diaphragm gauge (CDG) from Physikalisch-Technische Budensanstalt (PTB). The E n ratios represent an excellent agreement between NIMT and PTB calibration results.