OCP Oxidation Sub-Group Progress Update

Author: Ken Hope & Spencer Kerns, Chevron Phillips Chemical Company Collection: 2024 OCP Global Summit - Cooling Environments & Immersion

Summary

The OCP (Open Compute Project) Oxidation Stability Sub-Group, co-led by Ken Hope and Spencer Kerns of Chevron Phillips Chemical Company, is investigating how to measure and monitor the degradation of single-phase immersion cooling fluids over time. Fluid oxidation — the reaction of atmospheric oxygen with hydrocarbon-based dielectric fluids via a radical chain mechanism — is the primary driver of end-of-life determination for immersion fluids. Unlike engine oils, where oxidation science is mature, immersion cooling fluids operate under different temperature regimes and chemical environments, and much of the prior lubricant-industry methodology requires adaptation.

The sub-group reviewed four major standardized test methods — IEC 61125, ASTM D2272/D2112 (RPVOT), ASTM D943 (TOST), and ASTM D6186 (PDSC) — and is working to determine which is best suited to immersion cooling conditions. Key observable fluid degradation parameters include color change, kinematic viscosity, total acid number (TAN), and dielectric dissipation factor (DDF). Real-world in-service data from PAO 6 (polyalphaolefin 6) fluids operated at 30–40°C over up to 10 years shows meaningful viscosity increases and breakdown voltage drops after a decade of service, validating the need for periodic fluid monitoring.

Antioxidant additives (phenolic and aminic types) significantly extend fluid life: at 80°C, fluids without antioxidants reach an oxidation induction time (OIT) of approximately 4,000 minutes, while various antioxidant formulations can raise OIT substantially depending on additive type and concentration. A whitepaper documenting the sub-group's findings was planned for release in late 2024 or early 2025.