本国际标准规定了测定液态石油蒸气压的方法 基本上或完全由烃组分组成的产品，或含有以下的氧化烃 特定类型和指定的最大浓度。该方法不适用于这些浓度之外 水平，也不适用于任何含有甲醇或注释1中未涵盖的其他含氧烃的混合物。 注1含5个或5个以上碳原子的醚的最大浓度为15%(V/V)，乙醇为10% （V/V）。对于高级醇，最大浓度为7%（V/V）。 注2就本国际标准而言，术语“%(V/V)”用于表示A的体积分数 材料。 对于含有甲醇或注1范围以外的其他含氧碳氢化合物的石油产品， 应使用蒸汽压力测试方法。对于液化石油气，应使用ISO 4256。测试 方法可以应用于蒸汽压超过10kPa的挥发性原油，尽管 尚未评价精密度。 本国际标准中描述了四种程序。程序A和B是替代装置 Reid蒸气压高达180 kPa的产品配置，程序C适用于液体产品 里德蒸气压高于180 kPa，程序D适用于具有里德蒸气的航空汽油 大约50千帕的压力。 蒸气压是挥发性液体的重要物理性质，对挥发性液体具有关键的性能影响 汽车和航空汽油。蒸气压也是影响大气蒸发的性质之一， 因此越来越多地用于与排放和空气质量控制有关的法规中。蒸汽压为 也是在转移操作期间限制设备操作的性能和安全性的关键特性。 注意，因为外部大气压力被蒸汽中最初的大气压力抵消 腔室中，里德蒸汽压大约是37.8℃时的“绝对”蒸汽压。里德蒸汽压 由于样品的轻微蒸发和水蒸气的压力，与样品的真实蒸汽压不同 和密闭空间中的空气。

This International Standard specifies a method for the determination of the vapour pressure of liquid petroleum products consisting of essentially or wholly of hydrocarbon components, or containing oxygenated hydrocarbons of specific types and at specified maximum concentrations. The method does not apply outside these concentration levels, nor to any blends containing methanol or other oxygenated hydrocarbons not covered in note 1. NOTE 1 The maximum concentration of ethers containing 5 or more carbon atoms is 15 % (V/V), and for ethanol is 10 % (V/V). For higher alcohols, the maximum concentration is 7 % (V/V). NOTE 2 For the purposes of this International Standard, the term "%(V/V)" is used to represent the volume fraction of a material. For petroleum products containing methanol, or other oxygenated hydrocarbons outside the scope of note 1, a dry vapour-pressure test method should be used. For liquefied petroleum gases, ISO 4256 should be used. The test method may be applied to volatile crude petroleum with a vapour pressure exceeding 10 kPa, although the precision has not been evaluated. Four procedures are described in this International Standard. Procedures A and B are alternative apparatus configurations for products with a Reid vapour pressure up to 180 kPa, Procedure C is applied to liquid products with a Reid vapour pressure above 180 kPa, and Procedure D applies to aviation gasolines with a Reid vapour pressure of approximately 50 kPa. Vapour pressure is an important physical property of volatile liquids, and has critical performance implications for automotive and aviation gasolines. Vapour pressure is also one of the properties affecting atmospheric evaporation, and is therefore increasingly used in regulations relating to emissions and air quality control. Vapour pressure is also a critical property limiting the performance and safety of operation of equipment during transfer operations. NOTE Because the external atmospheric pressure is counteracted by the atmospheric pressure initially in the vapour chamber, the Reid vapour pressure is approximately the "absolute" vapour pressure at 37,8 °C. The Reid vapour pressure differs from the true vapour pressure of the sample owing to slight vaporization of the sample and the pressure of water vapour and air in the confined space.