ASHRAE TC 9.9 Liquid Cooling Classes (W17-W45) Explained
Understand the ASHRAE Thermal Guidelines liquid cooling classes W17 through W45: supply temperature ranges, delta-T limits, and how to select the right class for your deployment.
Updated
ASHRAE Technical Committee 9.9 (Mission Critical Facilities) publishes the Thermal Guidelines for Data Processing Environments. The 5th Edition (2021) renamed the liquid cooling classes after their maximum facility water supply temperature: W17, W27, W32, W40, W45 and W+ (previously W1 through W5). Each class also carries a 2°C (35.6°F) lower limit (ASHRAE TC 9.9, 2021).