DePriester Chart for Hydrocarbons
This Demonstration applies a DePriester chart, a set of nomograms to find the vapor-liquid equilibrium ratio (the gas phase mole fraction divided by the liquid phase mole fraction, known as the -value) for a series of hydrocarbons. Select one of three hydrocarbons: methane, propane or -decane. Use sliders to change the pressure and temperature; a green line connects these two points. The green circle indicates where to read the -value on the chart, which is also displayed above the chart. The -values for other hydrocarbons can also be read from the chart.
Contributed by: Majed N. Aldossary (October 2016)
Additional contributions by: Rachael L. Baumann and John L. Falconer
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA
Here is an example of how to use a DePriester chart for propane at 70 psia and 20 °F:
1. Use the sliders to set the pressure and temperature.
2. The green line connects these two points.
3. The -value is where the green line intersects the curve for propane ().
 J. M. Smith, H. C. Van Ness and M. M. Abbott, Introduction to Chemical Engineering Thermodynamics, 7th ed., Boston: McGraw-Hill, 2005.