Determination of base number in lubricants and additives by ASTM D2896: Substitution of chlorinated solvents and alternate electrolyte study

Abstract In the petroleum industry, the base number (BN) is used to measure reserve alkalinity. It is defined as the oil's potential to neutralize contaminants such as acids formed during its use. Commonly titration methods are used to measure the BN. However, the expression of BN data is method specific or defined as per the method. The widely accepted choice method is ASTM D2896 – “Standard Test Method for Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration” in fresh lubricants and additives. However, this method uses a chlorinated solvent, and due to its known adverse health effects, limited worldwide availability due to regulations, disposal, etc., there is a continuing effort in the industry to have a validated and widely applicable base number method that eliminates the usage of chlorinated solvents yet maintaining its performance. This work aims to evaluate suitable alternative solvents, including the one in the appendix of the ASTM D2896 method and alternative electrolyte solution. We will present the experimental findings and associated with applying alternative solvent and their impact on limited additives and finished lubricants.