Participation and Support Sought for Study of Vapor Pressure of Gasoline

ASTM D 6378, Standard Test Method for Determination of Vapor Pressure (VPx) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method) measures the vapor pressure of conventional and reformulated gasoline. Approved in 1999 by ASTM Committee D02 on Petroleum and Lubricants, it does not require air-saturation and chilling to 0º C prior to testing. The current test method specified in D 4814, Specification for Automotive Spark-Ignition Engine Fuel [2001], a U.S. regulatory requirement, is ASTM D 5191, Standard Test Method for Vapor Pressure of Petroleum Products (Mini Method) approved in 2001. However, D 5191 requires pre-test air saturation and chilling, making it difficult for online testing application.

In order that D 6378 be recognized by regulatory agencies and included in the gasoline specification, it has to be demonstrated and confirmed that D 6378 vapor pressure results are equivalent to D 5191 results.

A new task group was established recently by ASTM Subcommittee 8 on Volatility within Committee D02 to coordinate an interlaboratory study to determine whether methods D 6378 and D 5191 give equivalent results.

The interlaboratory study will involve:

• A variety of samples including different grades of conventional gasoline;
• Reformulated gasoline with MTBE, TAME, or ethanol oxygenate additives; and
• Pure hydrocarbons.

Due to the number of samples and participating laboratories required, as well as precautions to ensure sample integrity, the cost of the study is substantial. Organizations and laboratories are being sought to participate and make donations to defray the expenses anticipated. If D 6378 is demonstrated to give equivalent vapor pressure results relative to D 5191, it will allow online analysis for vapor pressure, thereby simplifying and facilitating compliance verification to regulations.

Interested organizations are urged to contact task group chairman Robert Falkiner, Imperial Oil Ltd., Toronto, Ontario, Canada (phone: 416/968-4184), or co-chairman Richard P. Biehle, Russel, Ky. (phone: 606/836-3455). Committee D02 meets Dec. 2-7 in Miami Beach, Fla. For meeting or membership details, contact Dave Bradley, manager, ASTM Technical Committee Operations (610/832-9681). //

Copyright 2001, ASTM