Advanced RSSOT (Rapid Small-Scale Oxidation Test) for characterisation of thermo-oxidative grease: New method DIN 51830-2 published

Demands relating to the overall properties of greases with increasing service longevity are becoming more and more challenging. In various applications, oxidation is dominant when it comes to degradation of greases affecting quality and properties. It is frequently a main factor influencing the product’s shelf life in a negative way. That’s why adequate lubrication across the entire service life must be ensured by quantifying the oxidation stability.

With RapidOxy 100 and its Rapid Small-Scale Oxidation Test (RSSOT) a powerful yet simple and quick determination of the oxidation stability of greases is already possible according to ASTM D8206 and DIN 51830-1. The instrument measures fully automatically in accordance with the optimum method in order to effortlessly screen, e.g., the effectiveness of antioxidants or formulations.

For the new DIN 51830-2 this existing RSSOT method was enhanced by integrating catalytically active materials and application of a new evaluation technique for grease failure (Oxidation Induction Time – OIT) at the German Institute for Standardization (DIN). This helps manufacturers and users to test grease under real application conditions and obtain better insights into product performance. In addition, both the RSSOT as well as the advanced test method enable the calculation of the Arrhenius activation energy. Knowledge of this value is a prerequisite for the determination of the grease service life under known temperature conditions of an application. To calculate the activation energy, the complete consumption of antioxidants in the grease is determined from the measured pressure curve.

The new method DIN 51830-2 was recently published. The advanced RapidOxy 100 method allows for:

• Oxidation stability testing closely related to real applications due to the contact of grease with catalytically active materials steel and brass
• Determination of activation energy for calculation of grease service life (Arrhenius)
• Estimation of Remaining Useful Life (RUL) for used greases

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