Petroleum Testing

During the measurement a stream of air is passed through the oil or fat sample contained in a sealed and heated reaction vessel. Oxidation of the oil or fat molecules in the sample results in the formation of peroxides as the primary oxidation products. Secondary oxidation products formed after the complete destruction of the fatty acids include low-molecular organic acids. These are transported in the stream of air to a second vessel containing distilled water whose conductivity is continuously recorded. The organic acids can be detected by the increase in conductivity. The time that elapses until these secondary reaction products appear is known as the induction time, induction period or Oil Stability Index (OSI).