Polaris Laboratories adopted the new American Society for Testing and Materials (ASTM) test method to measure the acidity of oils.
Released in December 2014, ASTM D7946 was designed to test the Initial pH (i-pH) of in-service lubricants. Compared to the previous method (ASTM D664), i-pH is superior for measuring the acidity or alkalinity of lubricants.
Polaris Laboratories uses pH to evaluate the strength of the acids present in compressors, natural gas engine and biogas engine lubricants. Typical operations (oxidation, blow-by of combustion gases) and environmental contamination increase the acidity of lubricants (which decreases the pH).
Most oils contain detergent and antioxidant additives to neutralize acid. As these additives are depleted, the lubricant no longer protects the internal components from corrosion. Oil analysis uses i-pH and acid number tests to determine if the lubricant is suitable for continued use and the oil drain can be extended, which saves time and money.
Source: Polaris Laboratories