ASTM D5482 Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method - Atmospheric)
1. Scope
1.1 This test method covers a procedure for the determination of total vapor pressure of petroleum products using automatic vapor pressure instruments. The test method is suitable for testing samples with boiling points above 0°C (32°F) that exert a vapor pressure between 7 and 110 kPa (1.0 and 16 psi) at 37.8°C (100°F) at a vapor-to-liquid ratio of 4:1. The test method is applicable to gasolines containing oxygenates. No account is made of dissolved water in the sample.
NOTE 1 - Because the external atmospheric pressure does not influence the resultant vapor pressure, this vapor pressure is an absolute pressure at 37.8°C (100°F) in kPa (psi). This vapor pressure differs from the true vapor pressure of the sample due to some small vaporization of the sample and dissolved air into the air of the confined space.
1.1.1 Some gasoline-oxygenate blends may show a haze when cooled to 0 to 1°C. If a haze is observed in 8.5, it shall be indicated in the reporting of results. The precision and bias statements for hazy samples have not been determined (see Note 6).
1.2 This test method is a modification of Test Method D5191 (Mini Method) in which the test chamber is at atmospheric pressure prior to sample injection.
1.3 This test method covers the use of automated vapor pressure instruments that perform measurements on liquid sample sizes in the range from 1 to 10 mL.
1.4 This test method is suitable for the determination of the dry vapor pressure equivalent (DVPE) of gasoline and gasoline-oxygenate blends by means of a correlation equation (see 13.2). The calculated DVPE is considered equivalent to the result obtained on the same material when tested by Test Method D4953.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. (For specific warning statements, see 7.2 through 7.7.)
2. Referenced Documents
2.1 ASTM Standards:
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4175 Terminology Relating to Petroleum, Petroleum Products, and Lubricants
D4953 Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method)
D5190 Test Method for Vapor Pressure of Petroleum Products (Automatic Method)
D5191 Test Method for Vapor Pressure of Petroleum Products (Mini Method)
3. Terminology
3.1 Definitions:
3.1.1 dry vapor pressure equivalent (DVPE), n - value calculated by a defined correlation equation, that is expected to be comparable to the vapor pressure value obtained by Test Method D4953, Procedure A.
3.1.2 gasoline-oxygenate blend, n - spark-ignition engine fuel consisting primarily of gasoline with one or more oxygenates.
3.1.3 oxygenate, n - oxygen-containing ashless organic compound, such as an alcohol or ether, which may be used as a fuel or fuel supplement.
3.1.4 platinum resistance thermometer, n - temperature measuring device with platinum wire, whose electrical resistance changes in relation to temperature.
3.1.5 total vapor pressure, n - observed pressure measured in the experiment, that is the sum of the partial pressure of the sample and the partial pressure of the dissolved air.
3.1.6 vapor pressure, n - pressure exerted by the vapor of a liquid when in equilibrium with the liquid.
3.2 Abbreviations:
3.2.1 DVPE, n - dry vapor pressure equivalent.
3.2.2 MTBE, n - methyl t-butyl ether.
