Measurements of the Gas Dependence of the Effective Area of a Piston Gauge Using H2, 3He, 4He, N2, CO2 and SF6

Abstract

Measurements have been performed to investigate the gas dependence of the absolute mode effective area Aeff of a piston gauge. The gases studied were H2, 3He, 4He, N2, CO2 and SF6. The data obtained were used to determine ΔAeff ≡ Aeff (gas) - Aeff (N2) in the pressure range 1,4 kPa to 103 kPa for 3He and 1,4 kPa to 162 kPa for H2, 4He, CO2 and SF6. Above 1,4 kPa, the uncertainty in ΔAeff was ⩽ 2 parts per million. The measurements yielded effective area differences ranging from 26 ppm at 1,4 kPa to 4 ppm at 45 kPa; from 100 kPa to 162 kPa, the maximum difference, to within the resolution of the measurements, was constant at 6 ppm to 7 ppm.