D323

D323-99a
Standard Test Method for Vapor Pressure of Petroleum Products (Reid Method)

1.1 This test method covers procedures for the determination of vapor pressure (See Note 1) of gasoline, volatile crude oil, and other volatile petroleum products. Procedure A is applicable to gasoline and other petroleum products with a vapor pressure of less than 180 kPa (26 psi). Procedure B may also be applicable to these other materials, but only gasoline was included in the inter-laboratory test program to determine the precision of this test method. Neither procedure is applicable to liquefied petroleum gases or fuels containing oxygenated compounds other than methyl -butyl ether (MTBE) (See Note 2). Procedure C is for materials with a vapor pressure of greater than 180 kPa (26 psi) and Procedure D for aviation gasoline with a vapor pressure of approximately 50 kPa (7 psi).

Note 1-Because the external atmospheric pressure is counteracted by the atmospheric pressure initially present in the vapor chamber, the Reid vapor pressure is an absolute pressure at 37.8°C (100°F) in kilopascals (pounds-force per square inch). 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 liquified petroleum gases refer to Test Method D-1267. For determination of the vapor pressure of gasoline-oxygenate blends refer to Test Method D-4953.

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