Server Inlet Temperature and Humidity Envelope
Calculates dew point and classifies server inlet air against entered recommended and allowable temperature.
Example
You enter
- Rack inlet dry bulb (deg F) 78
- Rack inlet relative humidity (%) 45
- Recommended minimum (deg F) 64.4
- Recommended maximum (deg F) 80.6
- Allowable minimum (deg F) 59
- Allowable maximum (deg F) 89.6
- Upper dew point limit (deg F) 59
- Upper relative humidity limit (%) 60
- Alternative dry bulb (deg F) 82
- Alternative relative humidity (%) 50
You get
- Entered dew point 54.9 deg F -- PASS
- Entered dew-point / RH margin 4.1 deg F / 15.0 points
- Alternative temperature at original RH 58.5 deg F dew point; margin 0.5 deg F
- Alternative condition 61.5 deg F dew point -- FAIL
- Alternative dew-point margin -2.5 deg F
Details, formula, and sources
Relative-humidity, and dew-point limits. It exposes the hot-and-humid corner where dry bulb passes but dew point fails; the installed equipment class governs.
dew point is calculated from dry bulb and RH with the Tetens correlation, then dry bulb, RH, and dew point are checked independently against entered recommended and allowable limits.
ASHRAE TC 9.9 thermal guidelines for data-processing environments and the Tetens saturation-vapor-pressure approximation. The current equipment-class limits govern.
The dew-point correlation is public; envelope limits are entered rather than reproducing a proprietary table.
Estimate. AHJ and licensed professional govern.
Field names used by the API: dry_bulb_f, relative_humidity_pct, recommended_min_f, recommended_max_f, allowable_min_f, allowable_max_f, upper_dew_point_f, upper_rh_pct, alternative_temp_f, alternative_rh_pct, dew_point_f, dew_point_margin_f, warm_same_rh_dew_point_f, alternative_dew_point_f, alternative_dew_point_margin_f
- Correlation range ordinary data-center air temperatures within the validated input boundsTetens correlation
- Steady inlet condition rack-level spatial and temporal excursions are not averaged into complianceASHRAE TC 9.9 / site survey