1.1 本试验方法包括在试验温度下，在大气压力下，具有足够蒸汽压力在空气中形成可燃混合物的化学品的可燃性浓度下限和上限的测定。该试验方法可用于在存在惰性稀释气体的情况下确定这些限值。不应使用比空气更强的氧化剂。 注1: 可燃性下限（LFL）和可燃性上限（UFL）有时分别称为爆炸下限（LEL）和爆炸上限（UEL）。然而，由于术语LEL和UEL也用于表示本测试方法中定义的限值以外的浓度，因此在报告或使用LEL和UE值时，必须仔细检查这些定义。 1.2 该试验方法基于电点火和火焰传播的视觉观察。如果火焰难以观察（例如，不规则传播或可见光谱中的发光不足），如果测试材料需要大的点火能量，或者如果材料具有大的淬火距离，用户可能会遇到问题。 1.3 附件A1 提供了一种针对可能难以点燃的具有大淬火距离的材料（如某些胺、卤化材料等）的改进测试方法。 1.4 在强点火源（如直接火焰点火）被认为是可信的其他情况下，使用在足够大的压力室内使用更高能量点火源的测试方法（例如，类似于测试方法中的方法 2007年2月 用于测量极限氧浓度）可能更合适。在这种情况下，可能需要专家建议。 1.5 可燃极限取决于试验温度和压力。该试验方法仅限于局部环境的初始压力或更低，实际下限压力约为13 kPa（100 mm Hg）。该设备的最高实际操作温度约为150°C。 1.6 以国际单位制表示的数值应视为标准。本标准不包括其他计量单位。 1.7 本试验方法应用于测量和描述材料、产品或组件在受控实验室条件下对热量和火焰的响应特性，而不应用于描述或评估材料、产品和组件在实际火灾条件下的火灾危险或火灾风险。 然而，该测试方法的结果可以用作火灾风险评估的要素，该评估考虑了与特定最终用途的火灾危险评估相关的所有因素。 1.8 本标准可能涉及危险材料、操作和设备。 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。 第节中给出了具体的预防说明 8. . 1.9 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 气体和蒸汽的LFL和UFL定义了空气中易燃浓度的范围。 5.2 该方法测量向上（和部分向外）火焰传播的LFL和UFL。火焰向下传播的极限较窄。 5.3 可燃极限可用于确定挥发性化学品的安全处理指南。它们特别用于评估气体和蒸汽处理的通风要求。NFPA 69为可燃性极限数据的实际使用提供了指导，包括使用的适当安全裕度。 5.4 正如Brandes和Ural中所讨论的， 4. ASTM和欧洲的可燃性测定方法之间存在根本的区别。ASTM方法旨在产生可燃性参数的最佳表示，并依赖于应用标准（如NFPA 69）规定的安全裕度。 另一方面，欧洲的测试方法旨在得出可燃性参数的保守表示。例如，在本标准中，LFL是最低和最高禁止浓度的计算平均值，而欧洲测试方法报告的LFL是五种最高禁止浓度中的最小值。 注2: 对于碳氢化合物，不可燃性和可燃性之间的断裂点出现在可燃性下限的狭窄浓度范围内，但在上限的断裂点不太明显。对于根据 13.1.1 可能具有大的淬火距离并且可能难以点燃，例如氨和某些卤代烃，这些材料的下限和上限可能不那么明显。也就是说，易燃和不易燃浓度之间存在更大的范围（参见 附件A1 ).

1.1 This test method covers the determination of the lower and upper concentration limits of flammability of chemicals having sufficient vapor pressure to form flammable mixtures in air at atmospheric pressure at the test temperature. This test method may be used to determine these limits in the presence of inert dilution gases. No oxidant stronger than air should be used. Note 1: The lower flammability limit (LFL) and upper flammability limit (UFL) are sometimes referred to as the lower explosive limit (LEL) and the upper explosive limit (UEL), respectively. However, since the terms LEL and UEL are also used to denote concentrations other than the limits defined in this test method, one must examine the definitions closely when LEL and UEL values are reported or used. 1.2 This test method is based on electrical ignition and visual observations of flame propagation. Users may experience problems if the flames are difficult to observe (for example, irregular propagation or insufficient luminescence in the visible spectrum), if the test material requires large ignition energy, or if the material has large quenching distances. 1.3 Annex A1 provides a modified test method for materials (such as certain amines, halogenated materials, and the like) with large quenching distances which may be difficult to ignite. 1.4 In other situations where strong ignition sources (such as direct flame ignition) is considered credible, the use of a test method employing higher energy ignition source in a sufficiently large pressure chamber (analogous, for example, to the methods in Test Method E2079 for measuring limiting oxygen concentration) may be more appropriate. In this case, expert advice may be necessary. 1.5 The flammability limits depend on the test temperature and pressure. This test method is limited to an initial pressure of the local ambient or less, with a practical lower pressure limit of approximately 13 kPa (100 mm Hg). The maximum practical operating temperature of this equipment is approximately 150 °C. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 This test method should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements of a fire risk assessment that takes into account all of the factors pertinent to an assessment of the fire hazard of a particular end use. 1.8 This standard may involve hazardous materials, operations, and equipment. 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 precautionary statements are given in Section 8 . 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 The LFL and UFL of gases and vapors define the range of flammable concentrations in air. 5.2 This method measures the LFL and UFL for upward (and partially outward) flame propagation. The limits for downward flame propagation are narrower. 5.3 Limits of flammability may be used to determine guidelines for the safe handling of volatile chemicals. They are used particularly in assessing ventilation requirements for the handling of gases and vapors. NFPA 69 provides guidance for the practical use of flammability limit data, including the appropriate safety margins to use. 5.4 As discussed in Brandes and Ural, 4 there is a fundamental difference between the ASTM and European methods for flammability determination. The ASTM methods aim to produce the best representation of flammability parameters, and rely upon the safety margins imposed by the application standards, such as NFPA 69. On the other hand, European test methods aim to result in a conservative representation of flammability parameters. For example, in this standard, LFL is the calculated average of the lowest go and highest no-go concentrations while the European test methods report the LFL as the minimum of the five highest no-go concentrations. Note 2: For hydrocarbons, the break point between nonflammability and flammability occurs over a narrow concentration range at the lower flammability limit, but the break point is less distinct at the upper limit. For materials found to be non-reproducible per 13.1.1 that are likely to have large quenching distances and may be difficult to ignite, such as ammonia and certain halogenated hydrocarbon, the lower and upper limits of these materials may both be less distinct. That is, a wider range exists between flammable and nonflammable concentrations (see Annex A1 ).