Immersion Integrated OCP Racks: The ORv3 Ecosystem Into Single-Phase Tanks

Author: Submer (presenter unnamed on slide, company co-founded by Daniel Pope and Pol Valls) Collection: 2024 OCP Global Summit - Cooling Environments & Immersion

Summary

This presentation by Submer documents the end-to-end qualification and production deployment of ORv3 (Open Rack Version 3) hardware ecosystem components inside single-phase immersion tanks, covering busbars, power shelves/PSUs, compute nodes, and network switches. Submer, founded in 2015 with hundreds of MWs deployed in production, frames itself as a primary contributor to OCP immersion standards — having co-authored OCP immersion requirements revisions (2.0 in 2021, 2.1 in 2023), material compatibility guidelines, safe handling guidelines, and leading the Fluids Committee and ORv3 Power Distribution workstream.

The technical content centers on Submer's Immersion Requirements qualification process for ORv3 hardware: a rigorous Excel-based checklist covering temperatures, flow rates, weight per square meter, water quality, material compatibility (including galvanic corrosion risks at connectors), busbar polarity marking, and PSU (Power Supply Unit) connector placement. Key engineering decisions include: moving PSU AC-to-DC connectors from the bottom to the top surface of power shelves to avoid capillarity and cable management issues; validating 1–3 busbar configurations per tank; and demonstrating that ORv3 busbars can handle up to 200 kW with less than 5°C temperature rise in worst-case immersion scenarios.

The load testing dashboard (Submer SmartPodXL × 4.4 ORv3, tested with Murata/Molex ORv3 hardware) shows PSU components operating in immersion at less than half their rated air temperature limits: for example, component C002 rated 150°C in air measured only 69°C in immersion at worst-case fluid setpoint of 55°C and maximum load. The full ORv3 integration rack layout delivers 100 kW in a single tank with 99 compute nodes (1 kW each), power shelves, busbars, and a CDU — with external 19" switches for network connectivity.