CHAPTER 6 - Calibration of Vacuum Gauges for Different Gases

Abstract

This chapter presents a brief discussion of vacuum gauge calibration techniques for gases other than nitrogen or argon. In many fields of vacuum application, it often becomes necessary to measure low pressures in systems containing gases different from those used for the gauge head calibration (usually nitrogen or argon). This is the situation when the rarefied environment is composed, for instance, of hydrocarbon or halogen gases, isotopes of hydrogen, or water vapor. Vacuum gauges required to measure pressure in such environments are calibrated either by determining their sensitivity for the unknown gas or vapor (ionization gauge heads) or by comparing their response to a pressure standard, in both cases under the same experimental conditions. The method used by Fursov (1970) for calibrating thermal-type gauge heads consists of subjecting the instrument to the pressure exerted by water vapor and measuring this pressure by balancing it against a known pressure. The chapter discusses the calibration techniques with hydrogen isotopes like deuterium and tritium and calibration with reactive gases like chlorine, tetraethyl lead, phenyl acetylene, iron carbonyl, hydrogen gases, and uranium hexafluoride.