ASTM D3339-08
Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration

Standard No.

ASTM D3339-08

Release Date

2008

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D3339-11

Latest

ASTM D3339-21

Scope

This test method measures the acid number of oils obtained from laboratory oxidation tests using smaller amounts of sample than Test Methods D 974 or D 664. It has specific application in Test Method D 943 in which small aliquots of oil are periodically removed for testing by Test Method D 3339. This test method, therefore, provides a means of monitoring the relative oxidation of oils, by measuring changes in acid number, at different time intervals and under the various oxidizing test conditions.

FIG. 1 Schematic Drawing of Typical Apparatus

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 18212;Some 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 28212;The 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

ASTM D3339-08 Referenced Document

• ASTM D1193 Standard Specification for Reagent Water
• ASTM D664 Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
• ASTM D943 Standard Test Method for Oxidation Characteristics of Inhibited Mineral Oils
• ASTM D974 Standard Test Method for Acid and Base Number by Color-Indicator Titration

ASTM D3339-08 history

• 2021 ASTM D3339-21 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2017 ASTM D3339-12(2017) Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2012 ASTM D3339-12 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2011 ASTM D3339-11 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2008 ASTM D3339-08 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2007 ASTM D3339-07 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2004 ASTM D3339-04 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2002 ASTM D3339-02 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 1995 ASTM D3339-95(2000)e1 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration
• 2000 ASTM D3339-95e2 Standard Test Method for Acid Number of Petroleum Products by Semi-Micro Color Indicator Titration