Panel -- Insights for Cleaner Liquid Cooling: Cleaning & Commissioning the TCS

Author: Don Mitchell, Victaulic (Moderator); Hussameddine Kabbani, Google; Pardeep Shahi, NVIDIA; John Herboth, Glue Collection: 2025 OCP Global Summit - Data Center Facility

Summary

This panel session, closing the Data Center Facilities and Cooling Environments tracks at OCP Global Summit 2025, addresses the commissioning and cleanliness requirements for Thermal Cooling Systems (TCS) in liquid-cooled data centers. The discussion is grounded in the OCP Modular TCS workstream's "Appendix G" white paper on commissioning for cleanliness, a comprehensive living document that integrates contributions from NVIDIA, Google, Victaulic, and the broader OCP community through monthly open calls with 70-80 participants. The panelists explore why liquid cooling cleanliness standards have become critical as cold plate channel widths shrink, filter requirements tighten to 25 microns (white blood cell size) and even 5 microns, and rack power densities push thermal loads and flow rates dramatically higher.

The panel debates the sequencing of cleaning, passivation, hydrostatic testing, flushing, and purging steps, the question of whether CDU manufacturers will allow their units to be used for flushing (some now say yes if pipe cleanliness can be demonstrated), and the emerging paradigm of modular pre-cleaned TCS pipe sections versus traditional jobsite fabrication. Modular delivery promises to drastically reduce on-site flush times (from 48+ hours with multiple chemical cycles to a short flush and sample), reduce chemical and water consumption (thousands of gallons are at stake), and accelerate time to delivery. However, the panelists emphasize that even with pre-cleaned modules, on-site verification through quantitative chemical analysis and filter differential-pressure monitoring remains mandatory given that billions of dollars of IT hardware are at risk.

The session concludes with a call to action for industry standardization: commissioning must start at design phase (day one), lessons should be drawn from the semiconductor industry's ultra-clean processes, and collaboration across companies is essential since no single organization will solve this alone. The white paper is hosted on a Google site for open commentary, and QR codes were provided for enrollment in the Data Center Facilities mailing list, TCS/CDU workstreams, and the new CDU Performance workstream.