Rarefied gas flow in pressure and vacuum measurements

Abstract

Flows of a gas through piston-cylinder gap of a gas-operated pressure balance and in general vacuum system have one similar aspect, i.e., the gas is rarefied due to small passage and low pressure, respectively. The flows in both systems could characterize in either slip flow regime or transition regime. Therefore, fundamental researches of flow in these regimes are useful for both pressure and vacuum metrology, especially for the gas-operated pressure balance where continuum viscous flow model is widely used for determining an effective area of pressure balance. The consideration of gas flow using suitable assumption would improve the accuracy of such calculation. Moreover, knowledge in rarefied gas flow contributes a predictability of gas behaviors in vacuum and low-flow leak detection system. This paper provides useful information of rarefied gas flow in both slip flow and transition regimes. Copyright © (2012) by the International Measurement Federation (IMEKO).