The Calibration Methods of Vacuum Pressure Gauges and Their Usage in Nuclear Researches

There are two criteria named primary and secondary standards, to calibrate vacuum pressure gauges. The most important primary standards are: "mercury manometer vacuum standard", "volume expansion vacuum standard" and "orifice flow vacuum standard", where they are used in low vacuum, medium vacuum and high vacuum ranges, respectively. In this paper we have tried to explain all the methods of standardizing vacuum pressure gauges and their scientific bases. We have also described briefly the importance and the usage of the methods which are applied in nuclear researches.