Phenolic inhibitor

Year of publication: 2006


Crucial for the long-term use of oils

Antioxidants (oxidation inhibitors) are added to almost all oils during production to protect the oil from oxidation and from aging too quickly. Most often, phenolic and aminic additives are used as antioxidants. Such additives intercept oxidative influences on the oil and neutralize them. They act as "radical scavengers" and are consumed in the process. Particularly in the case of turbine oils, but also in many other long-term applications, knowledge of the antioxidant content still present is therefore an important criterion in deciding whether the oil can be reused. This also applies to circulating and gear oils in industrial use or biodegradable hydraulic oils.

OELCHECK determines the phenolic inhibitor content for all turbine oils using infrared spectroscopy. Phenols exhibit a very characteristic absorption band in the range around the wave number of 3650 cm-1. The intensity of their signal is first determined by the IR instrument.

Using a calibration performed at OELCHECK using a pure additive, the absolute content of the inhibitor in the sample is then calculated from the signal intensity. If the oil type is known precisely and a fresh oil reference is available, the phenolic inhibitor content can also be given as a percentage compared to the fresh oil from these data. For practical purposes, it can be deduced to what extent the turbine oil can still counteract oxidation. Given a known initial situation and assuming that further use takes place under comparable conditions, it is thus possible to estimate how long the oil can still remain in service.