ASTM D323 Vapor Pressure of Petroleum Products (Reid Method)
Vapor pressure gives an indication of the evaporation rate of a substance. Substances with high vapor pressures typically evaporate more rapidly than substances with lower ones. Some localities regulate allowable vapor pressures of petroleum-based products to limit air pollution. This test determines the vapor pressure of crude oils, fuel oils and other volatile petroleum products. It may be used as a quality control tool, to assist in determining initial refinery treatment and to demonstrate adherence to local ordinances.
The sample is cooled, placed in the test chamber and brought to the test temperature. Pressure is recorded at regular intervals until a constant pressure is obtained. This pressure is reported in psi and kPa.