# Fluids & coolant treatment

Part ID: 5.09 · Layer 5 (Liquid cooling (IT-side: chip to CDU))

The coolant fluids that circulate through direct-to-chip and immersion loops, plus the chemical treatment (inhibitors, biocides) that keeps them stable over the life of the loop.

Three fluid families cover this part: single-phase dielectric fluids used mainly in immersion tanks; two-phase fluids that rely on evaporation and recondensation for either immersion or emerging two-phase cold-plate systems; and glycol-water blends with corrosion and biological inhibitors used in conventional direct-to-chip loops feeding cold plates and manifolds. Fluid choice is tied to the cooling architecture chosen upstream — a rack built for direct-to-chip cold plates uses a different fluid than an immersion tank — so this part depends on decisions made at 5.01 and 5.08. The category is in the middle of a real supply shift: one major two-phase and dielectric fluid producer is exiting part of its product line at the end of 2025 for PFAS-related reasons, which pushes qualification work toward the remaining suppliers and toward newer entrants developing alternative chemistries. Investors should watch how much of the exiting volume gets absorbed by other established chemical makers versus smaller, newer entrants, and whether operators standardize on a narrower set of approved fluids as PFAS scrutiny continues.

**AI delta:** The AI-driven shift of racks to direct-to-chip and immersion cooling created new, coolant-specific demand for glycol-water and dielectric fluid chemistries just as a major two-phase and dielectric fluid producer exits part of its line for PFAS-related reasons at the end of 2025.

## Companies

| Company | Role | Confidence | Ownership | Ticker | Note |
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Confidence tags: disclosed = company/filing statement; reported = trade press or partner list; inferred = taxonomy lead.