IT-agnostic DLC systems: key considerations (Daniel Bizo)

Overview

This article, by Daniel Bizo, was published in the Uptime Institute Journal in 2026. Its subject is the design of a single shared direct liquid cooling (water cold plate) secondary fluid network that can serve IT hardware from several vendors over multiple refresh cycles. Input came from operator briefings and from vendors Vertiv and Schneider Electric.

The main topics are coolant and wetted-material compatibility, coolant hygiene during commissioning and moves, filtration, manifold connection spacing, flow balancing and maintainability. According to the article, a quality PG25 or deionized-water coolant with the correct inhibitor package is technically compatible with the wetted parts of mainstream cold-plate systems; a wetted-materials list should be kept with all vendors, and OCP guidance applies.

For commissioning and change management, new equipment, including commissioning load banks, should be filled, flushed and drained by facility staff and tested for turbidity and pH against a retained factory sample. Industry-standard filtration for water DLC networks is 25 microns, usually full-flow at the CDU; side-stream filtration helps in multi-MW networks. For row-level SFN headers, closely spaced connection points are needed to suit different rack manifold positions and rack widths.

Adjustable or automated valves are needed to balance flow between racks with differing density, flow and pressure-drop needs. Full concurrent maintainability needs redundant supply and return manifolds to every rack, which is not guaranteed; alternatives include dual-fed manifolds. As a limit, the article is expert opinion, not a standard, and specific values should be confirmed with vendors. It does, however, offer a practical checklist for mixed-vendor liquid cooling networks.

Key points

1. A quality PG25 or deionized-water coolant with the correct inhibitor package is technically compatible with wetted parts of mainstream cold-plate systems; keep a wetted-materials list with all vendors (OCP guidance applies).
2. New equipment, including commissioning load banks, should be filled, flushed and drained by facility staff and tested for turbidity and pH against a retained factory sample.
3. Industry-standard filtration for water DLC networks is 25 microns, usually full-flow at the CDU; side-stream filtration helps in multi-MW networks.
4. Row-level SFN headers need closely spaced connection points to suit different rack manifold positions and rack widths.
5. Adjustable or automated valves are needed to balance flow between racks with differing density, flow and pressure-drop needs.
6. Full concurrent maintainability needs redundant supply and return manifolds to every rack, which is not guaranteed; alternatives include dual-fed manifolds.
7. Input came from operator briefings and vendors Vertiv and Schneider Electric.

Using it in design

• Catalogue DLC loops with coolant type (PG25/DI), filtration rating (default 25 micron) and wetted materials.
• Require balancing valves per rack branch in mixed-vendor loops.
• Warn when a Tier III claim relies on a single-fed rack manifold.
• Add a commissioning checklist item for flush and pH/turbidity sampling.

Who should read it

Engineers designing and commissioning liquid cooling networks, and operators hosting IT hardware from different vendors.

Related standards

• OCP Advanced Cooling Facilities guidelines
• ASHRAE TC9.9

Publication details

Authors

Daniel Bizo

Publisher

Uptime Institute Journal

Year

2026

Document language

English

Source type

Industry body

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation