ASTM D323-82e2 PDF

This test method covers a determination of vapor pressure (Note 1) of gasoline. It is also applied to volatile crude oil and other volatile petroleum products, except liquefied petroleum gases (Note 2). It is not applicable to oxygenated fuels.

Note 1 - Because the external atmospheric pressure is counteracted by the atmospheric pressure initially present in the air chamber, the "Reid vapor pressure" is an absolute pressure at 100°F (37.8°C) in pounds-force per square inch (or kilopascals) (kPa | kN/m²). The "Reid vapor pressure" differs from the true vapor pressure of the sample due to some small sample vaporization and the presence of water vapor and air in the confined space.

Note 2 - For determination of the vapor pressure of liquefied petroleum gases refer to Method D 1267.