Air - Psychrometric Chart for Standard Atmospheric Conditions - Imperial Units

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 20 ^oF to 120 ^oF
• with enthalpy units in Btu/lb

• Open the printable pdf file - Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury

The psychrometric chart is made with the PsycPro software available from www.linric.com.

• Transform between the Mollier diagram and the psychrometric chart
• Standard Atmospheric Pressure = 1 atm = 101.325 kN/m² = 101.325 kPa = 14.7 psia = 0 psig = 29.92 in Hg = 760 torr = 33.95 Ft.H₂O = 407.2 In.W.G (Water Gauge) = 2116.8 Lbs./Sq.Ft.

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:

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

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 lb_m = 0.0648 g  (7000 grains per lb_m)

• Heating, Cooling, Mixing, Humidifying and Dehumidifying Air Processes by Adding Steam or Water - Visualized in the Mollier diagram