1.1 本试验方法包括测定蒸汽压的程序（见 注1 )汽油、挥发性原油和其他挥发性石油产品。 1.2 程序A适用于蒸汽压低于180的汽油和其他石油产品 千帕（26 psi）。 1.3 程序B也可适用于这些其他材料，但实验室间试验程序中仅包括汽油，以确定本试验方法的精度。 1.4 程序C适用于蒸汽压大于180 kPa（26 psi）的材料。 1.5 程序D适用于蒸汽压约为50 kPa（7 psi）的航空汽油。 注1: 由于外部大气压力被蒸汽室中最初存在的大气压力抵消，因此里德蒸汽压力是37.8的绝对压力 °C（100 °F），单位为千帕（磅力/平方英寸）。由于一些小样本蒸发以及受限空间中存在水蒸汽和空气，里德蒸气压与样本的真实蒸气压不同。 1.6 本试验方法不适用于液化石油气或含有除甲基以外的含氧化合物的燃料 t -丁基醚（MTBE）。关于液化石油气蒸汽压的测定，请参阅试验方法 D1267号 或试验方法 D6897 . 关于汽油含氧混合物蒸汽压的测定，请参阅试验方法 D4953 . 自20世纪50年代初以来，原油的精度一直没有确定（见 附注3 ). 试验方法 D6377 已被批准为测定原油蒸汽压的方法。IP 481是一种测定原油空气饱和蒸汽压的试验方法。 1.7 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.8 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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。 第节给出了具体的警告声明 7. 和 18 和 12.5.3 , 15.5 , 21.2 , A1.1.2 , A1.1.6 和 A2.3 . 1.9 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 蒸汽压是挥发性液体的重要物理性质。本试验方法用于测定37.8℃下的蒸汽压 °C（100 °F），初始沸点高于0的石油产品和原油 °C（32 °F）。 5.2 蒸汽压对汽车和航空汽油都至关重要，影响启动、预热以及在高工作温度或高海拔下蒸汽锁定的趋势。在某些地区，作为控制空气污染的一项措施，汽油的最大蒸汽压限制是法定的。 5.3 原油蒸汽压对原油生产商和炼油厂的一般处理和炼油厂初始处理至关重要。 5.4 蒸汽压也可用于间接测量挥发性石油溶剂的蒸发速率。

1.1 This test method covers procedures for the determination of vapor pressure (see Note 1 ) of gasoline, volatile crude oil, and other volatile petroleum products. 1.2 Procedure A is applicable to gasoline and other petroleum products with a vapor pressure of less than 180 kPa (26 psi). 1.3 Procedure B may also be applicable to these other materials, but only gasoline was included in the interlaboratory test program to determine the precision of this test method. 1.4 Procedure C is for materials with a vapor pressure of greater than 180 kPa (26 psi). 1.5 Procedure D for aviation gasoline with a vapor pressure of approximately 50 kPa (7 psi). Note 1: Because the external atmospheric pressure is counteracted by the atmospheric pressure initially present in the vapor chamber, the Reid vapor pressure is an absolute pressure at 37.8 °C (100 °F) in kilopascals (pounds-force per square inch). The Reid vapor pressure differs from the true vapor pressure of the sample due to some small sample vaporization and the presence of water vapor and air in the confined space. 1.6 This test method is not applicable to liquefied petroleum gases or fuels containing oxygenated compounds other than methyl t -butyl ether (MTBE). For determination of the vapor pressure of liquefied petroleum gases, refer to Test Method D1267 or Test Method D6897 . For determination of the vapor pressure of gasoline-oxygenate blends, refer to Test Method D4953 . The precision for crude oil has not been determined since the early 1950s (see Note 3 ). Test Method D6377 has been approved as a method for determination of vapor pressure of crude oil. IP 481 is a test method for determination of the air-saturated vapor pressure of crude oil. 1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.8 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. Specific warning statements are given in Sections 7 and 18 , and 12.5.3 , 15.5 , 21.2 , A1.1.2 , A1.1.6 , and A2.3 . 1.9 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 Vapor pressure is an important physical property of volatile liquids. This test method is used to determine the vapor pressure at 37.8 °C (100 °F) of petroleum products and crude oils with initial boiling point above 0 °C (32 °F). 5.2 Vapor pressure is critically important for both automotive and aviation gasolines, affecting starting, warm-up, and tendency to vapor lock with high operating temperatures or high altitudes. Maximum vapor pressure limits for gasoline are legally mandated in some areas as a measure of air pollution control. 5.3 Vapor pressure of crude oils is of importance to the crude producer and the refiner for general handling and initial refinery treatment. 5.4 Vapor pressure is also used as an indirect measure of the evaporation rate of volatile petroleum solvents.