ASTM D909-18

5.1 Supercharge method ratings can provide an indication of the rich-mixture antiknock performance of aviation gasoline in aviation piston engines.

5.2 Supercharge method ratings are used by petroleum refiners and marketers and in commerce as a primary specification measurement to ensure proper matching of fuel antiknock quality and engine requirement.

5.3 Supercharge method ratings may be used by aviation engine and aircraft manufacturers as a specification measurement related to matching of fuels and engines.

1.1 This laboratory test method covers the quantitative determination of supercharge ratings of spark-ignition aviation gasoline. The sample fuel is tested using a standardized single cylinder, four-stroke cycle, indirect injected, liquid cooled, CFR engine run in accordance with a defined set of operating conditions.

1.2 The supercharge rating is calculated by linear interpolation of the knock limited power of the sample compared to the knock limited power of bracketing reference fuel blends.

1.3 The rating scale covers the range from 85 octane number to Isooctane + 6.0 mL TEL/U.S. gal.

1.4 The values of operating conditions are stated in SI units and are considered standard. The values in parentheses are the historical inch-pound units. The standardized CFR engine measurements and reference fuel concentrations continue to be in historical units.

1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.