ASHRAE TC 9.9
The industry committee whose A1-A4 air and W17-W45 water classes define the temperature envelopes IT gear can run in.
Current numbers
A1–A4 + H1 / W17, W27, W32, W40, W45, W+ASHRAE TC 9.9 air and liquid classes, fifth edition; separate 2024 liquid-cooling resiliency Technical Bulletin