Immersion Fluid Specification

Author: Jessica Gullbrand, Principal Engineer, Intel & OCP SC Co-Chair; Sandeep Ahuja, Sr. Principal Engineer, Intel; Je-Young Chang, Principal Engineer, Intel Collection: 2023 Global Summit - Cooling Environments

Summary

The OCP Base Specification for Immersion Fluids (Revision 1.0, approved December 2022) addresses a fundamental gap between immersion fluid development and IT equipment requirements. Intel authored the specification to bridge two disconnected communities: fluid suppliers offering a proliferating variety of single-phase and two-phase dielectric fluids, and data center operators whose IT equipment imposes specific thermal cooling and signal integrity (SI) requirements. Rather than specifying individual physical properties of fluids (which would require fluid suppliers to hit many independent targets), the specification defines four Figures of Merit (FOMs) that express what the fluid must do from the IT equipment's perspective: support natural convection, forced convection, acceptable pressure drop (single-phase), and critical heat flux (two-phase). Electrical parameters — dielectric strength, dielectric constant, dielectric loss tangent, and volume resistivity — are separately specified with hard limits.

As of October 2023, Intel has translated the specification into a structured six-phase fluid evaluation program. The evaluation progresses from tank/CDU material compatibility (Phase 1, complete) through package and system material compatibility (Phase 2, currently active, approximately 10 months post-approval) to functional component testing, system performance, reliability, and final fluid qualification (Phases 3–6, in progress or planned). Intel issued a Request for Information (RFI) to fluid suppliers, received proposals from multiple suppliers (sometimes multiple candidate fluids per supplier), assembled test kits of actual Intel Xeon server hardware and component materials, and sent those kits to suppliers to conduct OCP-methodology-compliant testing. The call to action at the close of the talk is for the industry to standardize around OCP-compliant immersion fluids and contribute to the OCP Fluids & Materials Working Group to expand material compatibility data for IT components.

The specification is publicly available on the OCP contribution webpage and includes an Excel tool for computing FOM values from user-provided fluid property inputs. Temperature evaluation points are 20°C, 25°C, 30°C, 40°C, 50°C, 60°C, and 70°C, with 25°C as the primary evaluation point; the specification must be met across the full 20–70°C range.