PG25 · 25% propylene glycol
The common direct-to-chip working fluid, chosen for its freeze, biocide, and material-compatibility envelope; topping it with another glycol or plain water quietly attacks seals and joints.
Current numbers
7.5–12 °Ctarget design delta-T across the loop; ~1.2–2.0 L/min per kW at PG25
~1.2–2.0 L/min/kWDLC flow rule of thumb (PG25); ~7.5–12 °C coolant delta-T target across the TCS
~1.5 L/min/kWDLC secondary-loop flow rule of thumb (PG25); ~170–235 LPM per NVL72 rack (1.2–2.0 L/min per kW)