Evaluation of thermooxidation stability of biodegradable recycled rapeseed-based oil NAPRO-HO 2003

The paper deals with the problems of introducing biodegradable oils in relation to the environmental protection. In the course of the research, the parameters were tested and improved of a number of rapeseed-based oils. Thus, two groups of oils were created to enable to distinguish raffinates and recycled oils. Recycling can remove the greatest disadvantage of raffinates, namely their thermo-oxidation instability, which becomes evident particularity by the formation of hardenable polymer deposits. The deposits result in the loss of the function of the components of the hydraulic circuit and gearbox. The methods of testing are based on the follow-up of the changes in acid value, kinematic viscosity at 40°C, water content, and peroxide number during the service life test. It has been proved that peroxide number characterises very well the thermo-oxidation stability, which is nearly unsatisfactory in raffinates. Within the cooperation in the international program KONTAKT, compliance tests were carried out of recycled rapeseed-based oil NAPRO 2003 in a hydraulic circuit and gearboxes. Their results are compared with the parameters of the best-recycled oils available.