Total Acid Number (TAN)

Total Acid Number (TAN) 

      Miligram of KOH required for nutralization of 1 gram of oil sample. 

      Miligram of KOH required per gram of oil sample or per 1 gram of oil sample.

      LTV = Low Tan Value

      MTV = More Tan Value

Total Acid Number (TAN) Total Acid Number (TAN) is a key measure used to determine the acidity of petroleum products, lubricants, oils, and other industrial fluids. It refers to the amount of potassium hydroxide (KOH), in milligrams, required to neutralize the acidic components in one gram of the sample. TAN is essential for monitoring the quality, stability, and condition of oils since acids present in fluids can lead to corrosion and oxidation, which damage machinery and equipment over time. Importance of TAN Measurement Corrosion Prevention: Acids in oils, such as sulfuric or organic acids, can cause corrosion in engines, pipelines, and other mechanical systems. High TAN levels indicate a higher risk of corrosion. Oxidation Monitoring: Over time, oils degrade due to exposure to oxygen, heat, and contaminants, resulting in the formation of acidic by-products. TAN helps assess oil degradation and its suitability for continued use. Lubricant and Oil Quality Control: Fresh oils and lubricants are tested for TAN to ensure they meet specified standards. A rise in TAN during use signals oil breakdown, contamination, or the need for replacement. Monitoring Refining Processes: In the petroleum industry, TAN is used to assess crude oil quality. Higher acidity in crude oil means increased refining costs due to corrosion risks. How is TAN Measured? TAN is measured through titration using a base solution, such as potassium hydroxide (KOH) or sodium hydroxide (NaOH), to neutralize the acids in the sample. The procedure is standardized under methods like ASTM D664 (for petroleum products) and ISO 6618 (for lubricants). Sample Preparation: A specific amount of oil or lubricant is dissolved in a solvent mixture, usually containing toluene, isopropanol, and water. Titration Process: The prepared sample is titrated with an alcoholic KOH solution. An indicator, such as potentiometry (using an electrode), detects the endpoint, which signifies complete neutralization of the acids. Result Calculation: TAN is expressed as milligrams of KOH required to neutralize the acids in one gram of the sample (mg KOH/g). Factors Affecting TAN Oxidation and Contaminants: Heat, air, and contaminants increase the rate of oil oxidation, generating acidic by-products and raising TAN values. Presence of Sulfur Compounds: Sulfur-rich oils tend to have higher TAN values due to the formation of sulfuric acids. Water Content: Water in oil can accelerate acid formation, affecting TAN values and causing corrosion in equipment. Oil Degradation: Prolonged use of lubricants without maintenance or filtration can increase TAN, signaling that the oil is no longer effective. Interpretation of TAN Values Low TAN: Fresh oils generally have low TAN values, indicating minimal acidity. Rising TAN: If TAN increases during use, it suggests oil degradation, contamination, or oxidation. High TAN: Oils with high TAN require immediate attention, as they can cause corrosion and equipment damage. Applications of TAN Measurement Petroleum Industry: Refineries use TAN to classify and process crude oils. High-acid crude oils are more challenging to refine and require corrosion-resistant infrastructure. Industrial Machinery: TAN monitoring helps assess the condition of lubricants in engines, turbines, and compressors, ensuring that equipment runs smoothly. Transformer Oils: Electrical utilities monitor TAN in transformer oils to detect early signs of oil breakdown, which could lead to equipment failure. Conclusion TAN is a crucial parameter in the maintenance and quality control of oils, lubricants, and petroleum products. It helps detect degradation, contamination, and acidity levels that could harm equipment and reduce efficiency. Regular TAN testing ensures timely maintenance, preventing costly repairs due to corrosion and wear. By monitoring TAN, industries can maintain the longevity of their equipment and ensure operational reliability.