Abstract
The national standards of pressure and vacuum in Japan have been developed, maintained and provided at the National Metrology Institute of Japan (NMIJ). The standards consist of several instruments such as mercury column manometer, pressure balances, static expansion system, and orifice method (continuous expansion method), etc. to cover a wide pressure range from 10−9 Pa to 109 Pa. These standards are disseminated domestically to the users through the calibration chain. The Japanese traceability chain is maintained by NMIJ, accredited calibration laboratories and the accreditation body so as to guarantee the reliability of the pressure and vacuum measurements for users. In this article, how the vacuum standards are developed from the pressure standard is explained then how they are maintained and disseminated are described.
