Total base number

Table 2.2. Typical parameter values for calcium sulfonates, alkylphenyl sulfides and alkylsalicylates detergents with additional total base number (TBN, mgKOH/g oil) from calcium carbonate. Formation of hard-core reverse micelles (RMs) of calcium carbonate-sulfonate or alkylphenate and soft-core revere micelles (RMs) of calcium alkylsalicylate in oil formulations...

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 term hard-core RMs is used to describe dispersions containing an excess of colloidal carbonate over that required to neutralize the sulfonic acid. The excess is found in calcium carbonate trapped in a micellar structure. The total base number (TBN) of the additive so obtained is 368 mg KOH/g of oil. The crude additive consisted of 33 wt% CaC03 (Delfort et al., 1995 Giasson et al., 1992). Some typical results of the core particle with the overall diameter and the detergent layer thickness are shown in Table 3.6 (Marsh, 1987). 

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)...

Total base number and total acid number values have been determined for a set of oil samples (Pawlak et al., 1985), curves II and III of Fig. 6.8. The two values cross over at a value of TBN = 2, after which the TAN values increase sharply and become meaningful. TBN values decrease sharply after the crossing point. The oil is now acidic and corrosive. The implications of the curves in Fig. 6.8 taken together are that the presence of water in oil could be potentially more damaging for "well-used" oils in service than for a fresh oil. 

Table 6.8. Relative total base number TBN change following aqueous extraction from engine lubricating oils (Fox et al., 1990)a...

Total acid number and total base number (fresh oil)... 

Used oil analysis. Used oil samples were analyzed for the following properties (Annual Book ASTM, 1985) viscosity ASTM D445, total base number ASTM D2896, total acid number ASTM D664, pentane insolubles ASTM D896, mass % zinc ASTM D811, mass % iron ASTM D811), "Active" zinc (differential infrared), carbonyl absorbance (differential infra-red). Over 250 samples were analyzed. 

Total base number a measure of the acid-neutralizing property of a lubricating oil. 

Total Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration... 

Samples of oil drawn from the crankcase can be tested to assess the reserve of alkalinity remaining by determining the total base number of the oil (ASTM D-664, ASTM D-2896, ASTM D-4739, IP 177, IP 276). Essentially, these are titration methods in which, because of the nature of the used oil, an electrometric instead of a color end point is used. The reserve alka-hnity neutralizes the acids formed during combustion. This protects the engine components from corrosion. However, the different base number methods may give different results for the same sample. 

Commonly, overbased substrates have been defined by the amount of total basicity contained in the product, for example, a 300 TBN (total base number) calcium sulphonate. Base number is defined in terms of equivalent amount of potassium hydroxide contained in the material. A 300 TBN calcium sulphonate contains base equivalent to 300 milligrams of potassium hydroxide per gram, or more simply, 300 mg KOH/g. This is the most convenient way to measure the amount of base present in oil, in a medium where pH is relatively meaningless and the primary base is not water soluble. 

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