Effect of Carrier Gas on the Sensitivity of Thermal Conductivity Detectors

Abstract

THE sensitivity of thermal conductivity detectors is proportional to the variation of the wire temperature (t) with the volume fraction (x) of the vapour in the carrier gas. Ray¹ has shown that for small values of x : where k ₁ and k ₂ are the thermal conductivities of carrier gas and vapour, respectively, and a is a constant depending on the geometry of the detector cell and the square of the wire current. This equation, and the conclusion drawn by Ray from it, has led to a discussion^2–6 of the merits of carrier gases of high and low thermal conductivity with respect to the sensitivity of thermal conductivity detectors.