Thermal envelope
Put in the inlet condition and the site altitude. The chart, the class table and the binding limit update as you type.
TC 9.9 Thermal Guidelines, 5th ed. (2021). Magnus saturation pressure; standard-atmosphere pressure at altitude.
Approach is the dry cooler’s leaving water minus entering air at design. Hours above the design dry-bulb are not modelled here — the system model does annual bins.
Warm-water cooling (W32 and above) rarely condenses; chilled-water-fed CDUs and rear-door coils are where this bites.
| Severity | Copper reactivity | Meaning |
|---|---|---|
| G1 mild | < 300 Å/month | Corrosion not a factor in reliability |
| G2 moderate | < 1,000 Å/month | Effects of corrosion measurable |
| G3 harsh | < 2,000 Å/month | High probability of corrosive attack |
| GX severe | ≥ 2,000 Å/month | Only specially designed equipment survives |
TC 9.9 guidance: keep copper below 300 Å/month and silver below 200 Å/month (coupon or reactivity monitor). Filter recirculated air at MERV 8 and outside air (economiser) at MERV 11 or 13.
MLC — mechanical load component: annualised cooling energy per unit of IT energy, compared against the climate-zone maximum in the standard.
ELC — electrical loss component: losses from the incoming service through UPS and distribution to the IT input, compared against the standard’s maximum.
Both are compared to tabulated limits in the edition adopted by the jurisdiction; this workbench does not reproduce those tables.
Recommended upper humidity raised to 70 % RH (with 15 °C dew point). New class H1 for high-density air-cooled products (allowable 5–25 °C, recommended 18–22 °C). Liquid classes renamed by maximum supply temperature: W17, W27, W32, W40, W45, W+ (formerly W1–W5).