Reid Vapor Pressure (RVP) is the vapor pressure of a mixture at 100°F. It is a common measure of the volatility of liquid hydrocarbons, and an important characteristic of gasoline. RVP of gasoline is also a regulated quantity in the USA and many other countries. The ASTM D323 method is used to determine the RVP of a fuel sample at a vapor-to-liquid ratio of four. In this respect, RVP is slightly different from true or total vapor pressure (TVP), which is defined as the pressure of a vapor in equilibrium with its condensed phase. RVP is available in the Surrogate Blend Optimizer as a property target.

For a surrogate blend, RVP is calculated based on the TVP of the blend. Vapor pressure data for fuel components are tagged in the sample along with thermo data, as described in Format for Property Tagging , and used to compute the vapor pressure of the blend. UNIFAC group interaction correlations (UNIFAC Activity Coefficients ) are used to calculate the activity coefficient to account for non-linear behavior of the blend vapor pressure. RVP is derived from the linear fit to TVP data for a handful of pure components and blends. Since RVP is derived from TVP in this fashion, it is referred to as the Reid Vapor Pressure Equivalent (RVPE).