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Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury

A psychrometric chart in English units - temperature ranging 20oF to 120oF

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The psychrometric chart below is made for standard atmospheric conditions.

  • English (Imperial) units with wet bulb and dry bulb temperature and relative humidity
  • barometric pressure 29.921 inches of Mercury
  • dry bulb temperature ranging 20oF to 120oF
  • with enthalpy units in Btu/lb

Psychrometric chart

The psychrometric chart is made with the PsycPro software available from

How to Use the Psychrometric Chart

The state of air with dry bulb temperature 70 oF and relative moisture 60% can be visualized in a psychrometric chart as indicated below:

How to use a psychrometric chart

From the chart - the saturation temperature is approximately 61 oF and that the humidity ratio is approximately 66 grains of moisture per pound of dry air.

Air with saturation temperature 63 oF and dry bulb temperature 75 oF can be visualized in the psychrometric chart as

How to use a psychrometric chart

From the chart - the relative humidity is approximately 50% and the humidity ratio is approximately 66 grains* of moisture per pound of dry air.

*grains of water is commonly used in psychrometrics

  • 1 grain = 0.000143 lbm = 0.0648 g  (7000 grains per lbm)
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Related Topics

Related Documents

Tag Search

  • en: psychrometric chart air moisture relative humidity wet bulb dry temperature
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  • Engineering ToolBox, (2004). Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury. [online] Available at: [Accessed Day Mo. Year].

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