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ASHRAE Fundamentals: moist air at 75 °F dry bulb, 50 % relative humidity, sea level

ToolPsychrometric Calculator
SourceAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (2021). ASHRAE Handbook: Fundamentals. ASHRAE, Peachtree Corners, GA. Chapter 1, Psychrometrics (psychrometric chart No. 1 and the moist-air property equations).
LevelProfessional

Problem

Find the humidity ratio, enthalpy, wet-bulb temperature and dew point of air at 75 °F dry bulb and 50 % relative humidity at standard sea-level pressure.

Inputs to Enter

  • Dry bulb 75 °F
  • Second property: relative humidity, 50 %
  • Altitude 0 ft (101.325 kPa)
Open the Psychrometric Calculator tool (loaded with this example)

Answers

  • W = 0.009236 lb/lb (chart 0.00927)
  • h = 28.13 Btu/lb above the 0 °F dry-air datum (chart 28.1)
  • Wet bulb 62.56 °F (62.5); dew point 55.18 °F (55.1)

Notes

The tool's default inputs are this case. Values from test-scripts/test_hvac.php (Hyland–Wexler saturation pressure; tolerances 0.3–0.5 %). Temperatures are plain numbers in °F (USCS) or °C (SI).

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