This paper investigates the air solubility of hydraulic oils with specific application in polyglycol based brake fluids. An Extensive literature research revealed a lack of data on the thermodynamic solubility properties of brake fluids. A derivation of the searched quantities cannot be obtained from the values given for hydraulic oils because of the deviation in components. Absolute values and relations to state variables, such as temperatures, have not yet been stated. Therefore, this research aims to investigate these unknown correlations using empirical measurements.
A test rig was designed for isobar absorption testing. The quasi-stationary test results confirm Henrys Law. Furthermore the solubility is presented as a function of temperature and water content and a phenomenological model of the Bunsen coefficient is derived. It is apparent that the impact of temperature is inverse to that of common fluids such as water or some alcohols.