Immersion cooling

Immersion cooling is a method that submerges servers in a dielectric liquid, a fluid that conducts heat but insulates electrically. In single-phase systems the liquid stays liquid and circulates through a heat exchanger. In two-phase systems it evaporates off hot parts, and the vapor condenses back into the bath. An open bath tank shares one pool among many servers and is serviced from the top. An enclosed chassis seals fluid inside each server.

The Open Compute Project (OCP) Immersion Requirements name synthetic hydrocarbons, esters and fluorochemicals as the main fluid groups. They require a flash point of at least 150 °C for any fluid. Vertiv rates a single CoolCenter Immersion tank at 120 kW on 12 °C chilled water, or 60 kW on 35 °C warm water. A 42U tank holds 950 L of fluid and weighs 1,102 kg wet, before servers. Vertiv also notes that servers in the tank need no fans.

Before submerging any server, get the maker's written warranty terms naming immersion and the exact fluid. OCP's immersion warranty guidelines note that almost all IT equipment warranties assume air cooling, often as the only approved use.

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Last verified October 7, 2026.