ASTM D4739-11(2017)
Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration

Standard No.

ASTM D4739-11(2017)

Release Date

2011

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM D4739-17

Latest

ASTM D4739-23

Scope

5.1 New and used petroleum products can contain basic constituents that are present as additives. The relative amount of these materials can be determined by titration with acids. The base number is a measure of the amount of basic substances in the oil always under the conditions of the test. It is sometimes used as a measure of lubricant degradation in service. However, any condemning limit shall be empirically established.

5.2 As stated in 1.2, this test method uses a weaker acid to titrate the base than Test Method D2896, and the titration solvents are also different. Test Method D2896 uses a stronger acid and a more polar solvent system than Test Method D4739. As a result, Test Method D2896 will titrate salts of weak acids (soaps), basic salts of polyacidic bases, and weak alkaline salts of some metals. They do not protect the oil from acidic components due to the degradation of the oil. This test method may produce a falsely exaggerated base number. Test Method D4739 will probably not titrate these weak bases but, if so, will titrate them to a lesser degree of completion. It measures only the basic components of the additive package that neutralizes acids. On the other hand, if the additive package contains weak basic components that do not play a role in neutralizing the acidic components of the degrading oil, then the Test Method D4739 result may be falsely understated.

5.3 Particular care is required in the interpretation of the base number of new and used lubricants.

5.3.1 When the base number of the new oil is required as an expression of its manufactured quality, Test Method D2896 is preferred, since it is known to titrate weak bases that this test method may or may not titrate reliably.

5.3.2 When the base number of in-service or at-term oil is required, this test method is preferred because in many cases, especially for internal combustion engine oils, weakly basic degradation products are possible. Test Method D2896 will titrate these, thus giving a false value of essential basicity. This test method may or may not titrate these weak acids.

5.3.3 When the loss of base number value, as the oils proceed in service, is the consideration, this test method is to be preferred and all values including the unused oil shall be determined by this test method. Base numbers obtained by this test method shall not be related to base numbers obtained by another test method such as Test Method D2896.

5.3.4 In ASTM Interlaboratory Crosscheck Programs for both new and used lubricants, historically Test Method D2896 gives a higher value for base number.

1.1 This test method covers a procedure for the determination of basic constituents in petroleum products and new and used lubricants. This test method resolves these co......

ASTM D4739-11(2017) Referenced Document

• ASTM D1193 Standard Specification for Reagent Water
• ASTM D2896 Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration
• ASTM D4057 Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177 Standard Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D664 Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration
• ASTM D974 Standard Test Method for Acid and Base Number by Color-Indicator Titration

ASTM D4739-11(2017) history

• 1970 ASTM D4739-23 Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2017 ASTM D4739-17 Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2011 ASTM D4739-11(2017) Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2011 ASTM D4739-11 Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2008 ASTM D4739-08e1 Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2008 ASTM D4739-08 Standard Test Method for Base Number Determination by Potentiometric Hydrochloric Acid Titration
• 2006 ASTM D4739-06a Standard Test Method for Base Number Determination by Potentiometric Titration
• 2006 ASTM D4739-06 Standard Test Method for Base Number Determination by Potentiometric Titration
• 2005 ASTM D4739-05 Standard Test Method for Base Number Determination by Potentiometric Titration
• 2002 ASTM D4739-02 Standard Test Method for Base Number Determination by Potentiometric Titration
• 1996 ASTM D4739-96 Standard Test Method for Base Number Determination by Potentiometric Titration