1.1 该试验方法包括确定选定体积的挥发性石油产品在0℃下饱和时形成的蒸汽的温度 °C至1 °C（32 °F至34 °F）产生101.3的压力 kPa（一个大气压）相对于真空。本试验方法适用于测定温度在36℃之间的样品 °C和80 °C（97 °F和176 °F），汽液比在8比1和75比1之间。 注1: 当汽液比为20:1时，结果应与试验方法确定的结果相比较 D2533 。 注2: 该试验方法也可适用于一个大气压以外的压力，但规定的精度可能不适用。 1.2 本试验方法适用于汽油和汽油含氧混合物。 1.2.1 一些汽油含氧混合物在冷却至0时可能会出现雾度 °C至1 °C。 如果在 12.5 ，应在结果报告中注明。模糊样本的精度和偏差说明尚未确定（见 附注12 )。 1.3 以国际单位制表示的数值应视为标准。 1.3.1 例外-- 括号中给出的值仅供参考。 1.4 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 有关具体警告，请参阅第节 7. 和小节 8.1.1 。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ===意义和用途====== 5.1 汽车发动机燃料系统中燃料蒸发的趋势由燃料的汽液比表示。 5.2 汽车燃油规格通常包括 T （V/L = 20 ) 以确保产品具有适当的挥发性性能。对于高环境温度 T （V/L = 20 ) ，表示具有低蒸发倾向的燃料，通常被指定；相反，对于低环境温度 T （V/L = 20 ) 是指定的。

1.1 This test method covers the determination of the temperature at which the vapor formed from a selected volume of volatile petroleum product saturated with air at 0 °C to 1 °C (32 °F to 34 °F) produces a pressure of 101.3 kPa (one atmosphere) against vacuum. This test method is applicable to samples for which the determined temperature is between 36 °C and 80 °C (97 °F and 176 °F) and the vapor-liquid ratio is between 8 to 1 and 75 to 1. Note 1: When the vapor-liquid ratio is 20:1, the result is intended to be comparable to the results determined by Test Method D2533 . Note 2: This test method may also be applicable at pressures other than one atmosphere, but the stated precision may not apply. 1.2 This test method is applicable to both gasoline and gasoline-oxygenate blends. 1.2.1 Some gasoline-oxygenate blends may show a haze when cooled to 0 °C to 1 °C. If a haze is observed in 12.5 , it shall be indicated in the reporting of results. The precision and bias statements for hazy samples have not been determined (see Note 12 ). 1.3 The values stated in SI units are to be regarded as standard. 1.3.1 Exception— The values given in parentheses are provided for information only. 1.4 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. For specific warnings, see Section 7 and subsection 8.1.1 . 1.5 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. ====== Significance And Use ====== 5.1 The tendency of a fuel to vaporize in automotive engine fuel systems is indicated by the vapor-liquid ratio of the fuel. 5.2 Automotive fuel specifications generally include T (V/L = 20 ) limits to ensure products of suitable volatility performance. For high ambient temperatures, a fuel with a high value of T (V/L = 20 ) , indicating a fuel with a low tendency to vaporize, is generally specified; conversely for low ambient temperatures, a fuel with a low value of T (V/L = 20 ) is specified.