Patent ID: 7569178
Filing Date: 2009-08-04
Classification: C21D,G01L

Abstract:
1. An apparatus for in-situ calibration of a vacuum gauge by absolute method and comparison method comprising: a fourth vacuum chamber filled with gas; first, second and third vacuum chambers to which gas of the fourth vacuum chamber is expanded and moved through pipes in order; calibrated vacuum gauges for respectively measuring pressures of the first, second and fourth vacuum chambers; a low vacuum gauge, a high vacuum gauge, vacuum gauges being calibrated and dummy vacuum gauges for measuring pressure of the third vacuum chamber; leak valves and opening and closing valves for controlling gas inflow and outflow of all of the vacuum chambers; a high vacuum pump and a low vacuum pump for exhausting all the vacuum chambers up to the ultimate pressure; and an orifice for stabilizing a flow of gas inside the third vacuum chamber.