VAPOR PRESSURE OF PETROLEUM PRODUCTS: ASTM D5190
EXPLANATION
This test method is applicable to air-containing, volatile petroleum products with boiling points above 0 ° C that exert a vapor pressure between 7 and 172 kPa at 100° F at a vapor-to-liquid ratio of 4:1. This test method is suitable for testing oxygenate containing gasolines. Using a correlation equation, this test method can calculate a dry vapor pressure equivalent which very closely approximates that obtained by Test Method ASTM D4953.
TEST SUMMARY
The chilled sample cup of the automatic vapor pressure instrument is filled with chilled sample and is coupled to the instrument inlet fitting. The sample is then automatically forced from the sample chamber to the expansion chamber where it is held until thermal equilibrium at 100° F is reached. In this process the sample is expanded to five times its volume (4:1 vapor-to-liquid ratio). The vapor pressure is measured by a pressure transducer. The measured vapor pressure is automatically converted to a dry vapor pressure equivalent value by the instrument.
TEST PRECISION
Repeatability: 2.48 kPa
Reproducibility: 3.45 kPa
Bias has not been determined.
