UC Merced

Foam inhibitors (FI)s are included in lubricant formulations to reduce foam tendency and stability. However, light-based automatic particle counters record some FI droplets as contaminants. In order to meet stringent cleanliness goals, the effects of the FI dispersion on ISO 4406 particle counts must be minimized. It has been shown previously that particle counts resulting from FIs can be reduced by filtration, but it is unclear if smaller FI droplets are also removed and how this may affect lubricant foaming. To perform this research, three test stations were constructed. We assembled a lubricant blending station that provides control over blending parameters such as, temperature, impeller speed, and container size. We obtained and repaired a nonoperational Koehler Dual Bath Foaming Characteristics Apparatus and developed replacement/alternative components for the apparatus that allowed us to conduct ASTM D892 foaming characterizations. Finally, we designed and constructed a filter station that circulates, filters, and particle counts fluids. The station includes an inline particle counter, adjustable flow rate, and accepts fluid viscosities ranging from 15 to 250 cSt. A base oil and foam inhibitor are circulated through the apparatus; fluid samples are taken as filtration progresses and then tested for foaming in accordance with ASTM D892. For each case, we characterize the effect of the inhibitor on fluid cleanliness and the effect of filter passes on particle counts and foam tendency/stability. These effects are investigated across two filter sizes and four additive chemistries. The results provide information about the relationships between additive chemistry, filter media, optically-detected oil cleanliness, and FI effectiveness.