ASTM D3339-08
Historical Standard: ASTM D3339-08 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
SUPERSEDED (see Active link, below)
ASTM D3339
1. Scope
1.1 This test method covers the determination of acidic constituents in new or used petroleum products and lubricants soluble or nearly soluble in mixtures of toluene, and isopropyl alcohol. The test method is especially intended for cases in which the amount of sample available to be analyzed is too small to allow accurate analysis by Test Methods D 974 or D 664 . It is applicable for the determination of acids having dissociation constants in water larger than 10 ? 9 . Extremely weak acids having dissociation constants smaller than 10 ? 9 do not interfere. Salts titrate if their hydrolysis constants are larger than 10 ? 9 .
1.2 This test method can be used to indicate relative changes in acid number that occur in an oil during use under oxidizing conditions. Although the titration is made under definite equilibrium conditions, the method does not measure an absolute acidic property that can be used to predict performance of an oil under service conditions. No general relationship between bearing corrosion and acid number is known.
1.3 Since this test method requires substantially less sample than Test Methods D 974 or D 664 , it provides an advantageous means of monitoring an oxidation test by changes in acid number by ( 1 ) minimizing test sample depletion for acid number analyses and thus minimizing the disturbance of the test or ( 2 ) allowing additional acid number analyses to be made while maintaining the same test sample depletion and thus providing additional data.
Note 1Some oils, such as many cutting oils, rust-proofing oils, and similar compounded oils, or excessively dark-colored oils, may be more difficult to analyze by this test method due to obscurity of the color-indicator end point. These oils can be analyzed by Test Method D 664 provided sufficient sample is available. However, this situation is much less likely using Test Method D 3339 than using Test Method D 974 due to the use of a more highly dilute sample during the titration and due to the greater stability of the end point color change. The acid numbers obtained by Test Method D 3339 may or may not be numerically the same as those obtained by Test Method D 664 but they should be of the same order of magnitude.
Note 2The results obtained using this method have been found to be numerically the same as those obtained using Test Method D 974 , within the precision of the two methods, for new or oxidized lubricants of the type primarily intended for hydraulic or steam turbine type service. The oxidized lubricants were obtained using the Test Method D 943 oxidation test. This correlation is shown by the correlation coefficient r = 0.989 with slope s = + 1.017 and intercept y = + 0.029, calculated using the acid numbers obtained using both titration methods for the samples used for the precision statement (12.2).
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see Sections 7 and 9, A1.1.4, A2.3.1, and A2.10.1.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
D664 Test Method for Acid Number of Petroleum Products by Potentiometric Titration
D943 Test Method for Oxidation Characteristics of Inhibited Mineral Oils
D974 Test Method for Acid and Base Number by Color-Indicator Titration
D1193 Specification for Reagent Water
Keywords
acid number; petroleum products; semi-micro color indicator titration;
ICS Code
ICS Number Code 75.080 (Petroleum products in general)
DOI: 10.1520/D3339-08
ASTM International is a member of CrossRef.
