W45
ASHRAE's liquid-cooling classes keyed to maximum facility-water supply temperature, where a higher number means warmer water: less chiller capex and heat-reuse potential, less thermal headroom.
Also written as: W17 · W27 · W32 · W40
Current numbers
89 L/min at 35 °C supply (59 L/min at 25 °C; 177 L/min at 45 °C)Lenovo GB300 NVL72 required rack flow by supply temperature (W45-rated); the ladder’s 35 °C row
~45 °Cwarm-water inlet band (W40/W45) GB200 & Rubin target — extends chiller-less hours; not a year-round guarantee
5th ed. (2021)ASHRAE fifth edition: W17/W27/W32/W40/W45/W+; new W40 and H1