Aging behavior of petroleum products
If stored in such a way that air has access, petroleum ages. During this process oxidizing reactions occur in the petroleum whose reaction products can lead to problems in combustion engines. The aging behavior (oxidation stability) is therefore a very important property of petroleum products.
Functionality of the Rancimat method
In order to determine the oxidation stability using the Rancimat method, air is first passed through the sample to be examined at an elevated temperature to bring about artificial aging. During this process long-chain organic molecules are oxidized by oxygen, whereby highly volatile organic substances form in addition to insoluble polymer compounds. The former are driven out by the air current, absorbed in water and detected there by measuring the conductivity.
The Oil Stability Index (OSI)
The time until formation of these decomposition products occur is referred to as the induction time or the Oil Stability Index (OSI) and characterizes the resistance of the sample towards oxidative aging processes, i.e. the oxidation stability.
