Popis

Oils continually react with atmospheric oxygen to produce organic oxidation products that are acidic in nature. At ambient temperature, this reaction is very slow and has little effect upon oil conditions.

At the elevated temperatures that exist within an operating engine, reaction rates are much higher. Elevated operating temperatures can generate high levels of weak organic acids. They cause increased oil viscosity and can deposit as lacquers on hot surfaces.

Total Acid Number or TAN is the measure of both the weak organic and strong inorganic acids present in oil. It is applicable to gearbox, gas engine, gas turbine and hydraulic lubricants. It is an important quality measurement of crude oil. The TAN value indicates to the crude oil refinery the potential of corrosion problems
Total Acid Number is an analytical test to determine the deterioration of lubricants. The more acidic a lubricant is, the further its degradation has proceeded.
Theoretically, the Total Acid Number (TAN) is the amount of potassium hydroxide in milligrams that is needed to neutralize the acids in one gram of oil.
TAN value can be measured by potentiometric titration. The sample is dissolved in toluene and propanol with a little water and titrated with alcoholic potassium hydroxide. A glass electrode and reference electrode is immersed in the sample and connected to the instrument. The meter reading (in millivolts) is plotted against the volume of titrant. The end point is taken at the distinct inflection of the resulting titration curve corresponding to the basic pH 11 buffer solution.