Significance and Use

This test method provides a semiquantitative estimate of the acid number of lubricating oils obtained from laboratory oxidation tests using smaller amounts of sample than Test Methods D 974, D 664, or D 3339 . It has specific application in Test Method D 943 and in Test Method D 4871 . This test method, therefore, provides a means of monitoring the relative oxidation of lubricating oils by measuring changes in acid number, at different time intervals and under various oxidizing test conditions.

Since this test method is semiquantitative, each laboratory shall develop its own criteria for each oxidation test method for determining when to switch from this semiquantitative test method to a more precise test method for acid number.

1. Scope

1.1 This test method is a semiquantitative micro method intended for monitoring the changes in acidic constituents occurring in lubricating oils during oxidation testing, when the acid number of such oils falls within the range from 0.02 to 1.0 mg of potassium hydroxide per gram of sample. It is applicable to such oils as turbine oils, hydraulic oils, and other circulating oils. Note 1 - This test method is a micro version of Test Method D 974 and it produces results similar to that method.

1.2 This test method is designed for use where sample size is limited. It shall not be used as a replacement for higher precision methods such as Test Methods D 974 or D 664. It shall not be used to monitor oils in-service.

1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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.

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

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

D4871 Guide for Universal Oxidation/Thermal Stability Test Apparatus

Keywords

acid number; color indicator titration; oxidation testing; semiquantitative: Acid number--petroleum products; Lubricating oils; Oxidation testing--petroleum products; Semiquantitative determination; Used lubricating oils;

ICS Code

ICS Number Code 75.100 (Lubricants, industrial oils and related products)

DOI: 10.1520/D5770-11

ASTM International is a member of CrossRef.

ASTM D5770