Total acid number TAN

Total acid number (TAN) is a measure of the amount of acid or acid-like material in the oil sample. Because new oils contain additives that affect the TAN number, it is important to compare used oil samples with new, unused, oil of the same type. Regular analysis at specific intervals is important to this evaluation. 

The oil analyses have shown that the TBN values of lubricating oils deplete completely while at the same time, the corrosion rate can be considerably reduced. The relationship between the solubilization of large quantities of acid, total base number (TBN), and total acid number (TAN) values with the rate of corrosion is still unresolved. TAN values are not a good prediction of corrosion, and the source of extra TBN is much more important in the neutralization of corrosive acids than the simple numerical value of TBN. The effect of hard-core RMs shows poor correlation between used oil sample TAN values and the potential for bearing corrosion (Denison, 1944 Kreuz, 1970). Where corrosion rates are reduced by treatment with hard-core reverse micelle detergent, and no significant reduction in TAN has occurred, corrosion protection must have occurred by a... 

The corrosive activity on copper/lead bearings for typical carboxylic acids, such as decanoic, lauric, palmitic, stearic, and oleic acids, as 1 % w/w solutions in a lubricating oil base stock with excess of hard-core RMs, measured by infrared spectroscopy, supports the observation for the corrosive activity of used lubricating oils. An increase in total acidic number (TAN) is generally either an indication of contamination with acidic combustion products or the result of oil oxidation. Corrosion of bearing metals by used lubricating oils requires the presence of both acids and peroxides and probably takes place by a two-step mechanism. In the first step, the peroxide reacts with the metal to form a metal... 

The oil deterioration mechanism, various deterioration indicators (viscosity change, total base number (TBN), total acid number (TAN), insolubles concentration, etc.) have been proposed and their respective detecting methods were reported. The oil deterioration component is divided into two general categories deterioration of the base oil and ingression of foreign matter. Ultimately, however, particles are considered to exist in engine oil in the form of insoluble elements. Fig. 6.1 shows the mechanism of the oil deterioration (Tomita et ah, 1995). 

The remaining useful life evaluation routine (RULER) is a useful monitoring program for used engine oils. The RULER system is based on a voltammetric method (Jefferies and Ameye, 1997 Kauffman, 1989 and 1994). The data allows the user to monitor the depletation of two additives ZDDP and the phenol/amineH+ antioxidant. The RULER results were compared to other standard analytical techniques, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), total base number (TBN), total acid number (TAN), and viscosity to determine any correlation between the techniques (Jefferies and Ameye, 1997 and 1998). The test concluded that the RULER instrument can... 

Table 6.3. Techniques and methods for the determination of total base number (TBN, mg KOH g 1 oil) and total acid number (TAN, mg KOH g 1 oil), (Fox et al., 1991)...

Table 6. 7. Results of the total base number TBN, total acid number TAN, lead content from the field and bench tests of diesel engine oil (Van Dam et al., 1997)...

Emulsification with caustic is possible with oils that have a fairly high total acid number (TAN). Below about 1.5 mg KOH/gm oil, the oils either will not emulsify or will form water-in-oil emulsions. The rate of emulsification with caustic is much faster than emulsification with surfactant mixtures, which is a characteristic property for emulsions generated via the agent-in-oil procedure (1 ). 

The total acid numbers (TAN) and the experimentally determined optimal NaOH concentrations for Kern River, Wilmington, and other viscous, asphaltic crude oils are given in Table III. 

Total Acid Number (TAN) A property of crude oil. The acid number expresses the amount of base (potassium hydroxide) that will react with a given amount of crude oil in a standardized titration procedure. A large acid number indicates a high concentration of acids in the oil, usually including natural surfactant precursors. 

Absolute porosity, definition, 220 Absolute viscosity, definition, 386 Acid number (total acid number, TAN), definition, 403 Adhesion, definition, 26-27 Adsorbed polymer layers, interaction with droplets, 62 Adsorption definition, 386... 

Both methods involve heating the lubricant to temperatures in excess of 200°C with a high volume of air being passed through the sample for extended periods of time. Despite the different approaches both methods assess the effect on the lubricant in much the same way by measuring increases in viscosity, total acid number, TAN, and insolubles content. Method 9 additionally assesses volatility loss and formation of a solidus , essentially the point at which the sample no longer flows. FTM 5308 adds the dimension of assessing the effect of the oxidised lubricant on metal test pieces, namely ... 

Sulphur content and total acid number (TAN) of Magnolia oils and condensates inversely correlate with liquid API gravity (Table 1). Although sulphur and TAN are known to increase as a consequence of biodegradation (Behar Albrecht 1984 Meredith et al. 2000 Watson et al. 2002), both may be influenced by source rock maturity (Dias et al. 2002). In view of the discussion above, low maturity is viewed as being more likely responsible for the modestly elevated sulphur and TAN content in some of the Magnolia fluids. 

Neutralization Number. The neutralization number (neut. no.) is a measure of the acidity or alkalinity of an oil. Usually reported as the total acid number (TAN) or total base number (TBN), it is expressed as the equivalent nulhgrams of potassium hydroxide required to neu-trahze the acidic or basic content of a 1-g sample of oU. Increases in the TAN or decreases in the TBN are usually indicators that oxidation has occurred. 

The need for this acid neutralization capacity is evident from Fig. 3, which shows the continual decrease in total base number (TEN) and increase in total acid number (TAN) for a high- and low-TAN gasoline engine oil. The TBN/TAN equivalence point occurs at aroimd 3000 to 6000 miles. (The metal content in the drain increases after the equivalence point is reached in field testing.) Typically, at this point, acids build up to unacceptable levels, and it is, therefore, desirable to change the oil before the TEN and TAN cross. 

Muller, Hendrik Pauchard, Vincent O., Hajji, Adrian A., (2009). Role Naphthenic Acids in Emulsion Tightness for a Low Total Acid Number (TAN)/High asphaltenes Oil Characterization of the Interfacial Chemistry. Energy Fuels, 23,1280-1288... 

Naphthenic acid is a kind of organic acid in crude oils and has a saturated ring structure. Its content is typically measured and indirectly expressed by non-aqueous titration with potassium hydroxide (mg KOH per 100 ml for clean oils) or total acid number (TAN, as milligrams of KOH required to neutralize the acid in one gram of oil). Naphthenic acid in crude oils is a rather complex mixture. Its molecular weight ranges from 180 to 700, mainly from 300 to 400 [4]. 

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