Effects of Contaminants on Demulsibility and Foam Levels of Engine Lubricants

Abstract

Lubricants, such as engine oils and hydraulic oils, are a critical component in many industrial applications, and its quality directly affects equipment performance and lifespan. However, their performance can be severely compromised when water mixes with the oil due to poor separation. The presence of contaminants in lubricating oils can lead to demulsibility failure, allowing water to become miscible with the oil, thereby causing it to foam. The propensity of lubricating oils to foam poses a significant challenge in applications like high-speed gear transmissions, high-volume pumping, and spray lubrication systems. Foaming leads to intermittent lubrication, lubricant loss through overflow, and potentially catastrophic consequences, including mechanical damage, cavitation, reduced product lifespan, and increased maintenance expenses. This study investigates the effects of common contaminants - grease, used oil, dust and fuel - on the demulsibility and foam levels of fresh lubricating oils. Testing was conducted using ASTM D1401 demulsibility test procedure and ASTM D892 foam test procedure. The results show that grease has the most significant impact, causing a substantial increase in emulsion layer volume. Dust and used oil also negatively affect demulsibility and foam levels in lubricants, while fuel has no significant impact. There is a correlation between demulsibility and foam levels, with poor demulsibility often leading to excessive foaming. The findings highlight the importance of controlling contamination to maintain the performance and lifespan of lubricants. Regular oil analysis and contamination control measures are essential to maintaining optimal oil quality.