ASTM D4953 Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends
ASTM D4953 Standard Test Method for Vapor Pressure of Gasoline and Gasoline-Oxygenate Blends (Dry Method)
5. Apparatus
5.1 The apparatus for Procedure A is described in Annex A1.

5.2 The essential dimensions and requirements for the liquid and vapor chamber for Procedure B are identical with those for Procedure A and described in Annex A1. External fittings and features will vary depending on whether a gage or transducer is used and the provision for rotating the apparatus in the bath. Details of a commercially available unit are shown in Annex A2.

6. Handling of Test Samples
6.1 This section applies to both Procedure A and B.

6.2 The extreme sensitivity of vapor pressure measurements to losses through evaporation is such as to require the utmost precaution and the most meticulous care in handling of samples.

6.3 Sampling shall be done in accordance with the Reid Vapor Pressure section (10.3) of Practice D4057 except for fuels containing oxygenates where the Water Displacement Procedure section (10.3.1.8) of D4057 must not be used.

6.4 Sample Container Size:
6.4.1 The size of the sample container from which the vapor pressure sample is taken shall be 1 L (1 qt). It shall be 70 to 80 % filled with sample.

6.4.2 The present precision statement has been derived using samples in 1-L (1-qt) containers. Samples taken in containers of other sizes as prescribed in Practice D4057 can be used if it is recognized that the precision can be affected. In the case of referee testing the 1-L (1-qt) sample container shall be mandatory.

6.5 Hazard:
6.5.1 The vapor pressure determination shall be the first test withdrawn from the sample container. The remaining sample in the container cannot be used for a second vapor pressure determination. If necessary, obtain a new sample.

6.5.2 Samples shall be protected from excessive heat prior to testing.

6.5.3 Samples in leaky containers shall not be tested. Discard and obtain a new sample.

6.6 Sample Handling Temperature - In all cases, the sample container and contents shall be cooled to 0 to 1°C (32 to 34°F) before the container is opened. Sufficient time to reach this temperature shall be assured by direct measurement of the temperature of a similar liquid in a like container placed in the cooling bath at the same time as the sample. See A1.3.1.