In-Service Oil Monitoring

A proposed ASTM International standard will help determine the remaining level of phenolic compounds in lubricating oils. ASTM’s committee on petroleum products, liquid fuels, and lubricants (D02) is developing the proposed standard, which describes a trend analysis process using Fourier transform infrared (FT-IR) spectrometry.

Phenolic compounds are widely used in engine, hydraulic, and other types of oils to protect against oxidation. The proposed standard (WK73062) will help machine operators recognize severe operating conditions before base oil degradation and machinery failure.  

“Phenols act as primary radical scavengers, thus preventing the oil from being oxidized,” says ASTM International member Thomas Fischer, scientific director, Oelcheck. “Their concentration, however, decreases during a regular oil lifecycle.”

Fischer notes that a precise knowledge of the remaining antioxidant level is an essential aspect of proactive maintenance and that the procedure described in the proposed standard is well-suited to this purpose.

“Instrumentation is widely available in laboratories,” says Fischer. “The measurement is relatively simple and fast. Determination of phenols using FT-IR is less prone to formulation or matrix effects than other techniques, such as voltammetry.”

Maintenance and service departments monitoring in-service oils will be the primary users of the proposed standard.