Page 265 - Gas Adsorption Equilibria

5. Oscillometry 251

Also is the dynamic viscosity of the sorptive gas and is a characteristic
parameter of the rotator - sorbent system to be determined from calibration
measurements with a non-adsorbing gas, preferably helium or argon, via the
equation

indicating the rotator’s relaxation time in helium in a thermodynamic
state with dynamic viscosity

If has been determined from helium measurements and is
known from calibration measurements with a dense, i. e. non-adsorbing
loading material in the bowl, can be calculated from via (5.47).

We finally would like to mention that for a non-adsorbing dense rotator
the viscosity of the surrounding gas can be calculated from relaxational time
measurements by the formula

Here indicate the dynamic viscosity and the relaxation time of
rotator’s motion in an arbitrary reference state [5.4]. *)

2.3 Uncertainties or Errors of Measurement

We here present a formula allowing one to calculate numerically the
dispersions or mean square deviation (MSD) of Gibbs excess masses of
adsorbates which have been measured oscillometrically and
calculated by Eq. (5.44). The Gauss law of error propagation leads to the
expressions [5.17, 5.18]:

* ) For more details and actual information on rotator-viscometers the interested reader should
contact Rubotherm Company at Bochum and / or the Institute of Thermo- and
Fluiddynamics at the University of Bochum, Bochum, Germany.