Contactless weighing up to high pressures for analysing adsorption and density of fluids

Adsorption of supercritical fluids methane, nitrogen and argon by active ca rbons was studied up to a pressure of 500 bar. A three-parameter isothermal equation was used to represent the adsorption equilibrium. This isothermal equation is based on a physical model conception which had already been us ed for the modelling of adsorption processes with a pressure up to 150 bar. Beside the exact knowledge of the measurable parameters pressure, temperat ure and fluid composition, the density of the adsorbate are essential for t he evaluation of the adsorption analysis. The fluid density can be determin ed either via equations of state, which is normally the most practicable an d fastest way, or via lift measurements of a lowering body in the fluid bas ed on the principle of Archimedes. This work represents and discusses the q uestion of to what extent the fluid density determined under real condition s via equations of state, using, for example, equation of Bender, correspon ds to the fluid density measured under high-pressure.