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
- Open the printable pdf file - Psychrometric Chart - Barometric Pressure 29.921 inches of Mercury
- 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 lbm = 0.0648 g (7000 grains per lbm)
Moist and humid air - psychrometric charts, Mollier diagrams, air-condition temperatures and absolute and relative humidity and moisture content.
Basic air changing state processes - heating, cooling, mixing, humidifying and dehumidifying by adding steam or water - psychometric diagrams and the Mollier charts.
Air can be humidified by adding water or steam.
Estimate the amount of steam required (lb/h in 100 cfm) in humid air.
Using steam to humidify air.
Relative humidity in moist air can estimated by measuring the dry and wet bulb temperature.
Classification of dehumidifiers.
Dry and wet bulb temperatures, saturation pressure, water vapor weight, specific volume, heat and more.
Dry and wet bulb temperature, specific volume, relative humidity, enthalpy and more.
The Mollier diagram is a graphic representation of the relationship between air temperature, moisture content and enthalpy - and is a basic design tool for building engineers and designers.
The relationship between the psycrometric chart and the Mollier diagram.
The definition of STP - Standard Temperature and Pressure and NTP - Normal Temperature and Pressure.