Reid vapor pressure (RVP) is the measure of the volatility of gasoline or other petroleum products and is defined as the absolute vapor pressure exerted by the vapor of the liquid and any dissolved gases at 37.8 °C (100 °F) and is defined in PSI or Kilopascal.
It is important to measure to avoid high levels of vaporization so that products are not lost to atmosphere or the pumps are vapor locked. Moreover, in winter low vapor pressure may cause difficulty in starting the engine. Therefore, oil refineries control the RVP seasonally to maintain gasoline engine reliability.
ASTM D323, test method is applied to measure the RVP of crude oil and petroleum refined products.