1.1 本试验方法涵盖了在试验温度下，在大气压力下，具有足够蒸汽压以在空气中形成易燃混合物的化学品易燃性的下限和上限浓度的测定。本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。不得使用比空气强的氧化剂。 注1: 可燃下限（LFL）和可燃上限（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也用于表示本试验方法中定义的限值以外的浓度，因此在报告或使用LEL和UEL值时，必须仔细检查定义。 1.2 本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，可见光谱中的不规则传播或发光不足），如果测试材料需要较大的点火能量，或者如果材料具有较大的熄灭距离，用户可能会遇到问题。 1.3 附件A1 提供了一种改进的材料（例如某些胺、卤化材料等）的测试方法，这些材料具有可能难以点燃的大淬灭距离。 1.4 在其他认为强点火源（如直接火焰点火）可靠的情况下，使用在足够大的压力室中使用高能点火源的试验方法（例如，类似于试验方法中的方法） E2079年 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，实际压力下限约为13 kPa（100 mm Hg）。该设备的最高实际工作温度约为150°C。 1.6 以国际单位制表示的数值应视为标准值。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和火焰的响应特性，不应用于描述或评估材料、产品或组件在实际火灾条件下的火灾危险或火灾风险。 然而，本试验方法的结果可作为火灾风险评估的要素，该评估考虑了与特定最终用途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）。本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 第节给出了具体的预防说明 8. ====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（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 易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为易燃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 正如布兰德斯和乌拉尔所讨论的， 4. ASTM和欧洲易燃性测定方法之间存在根本差异。ASTM方法旨在产生易燃性参数的最佳表示，并依赖于应用标准（如NFPA 69）施加的安全裕度。 另一方面，欧洲试验方法旨在得出易燃性参数的保守表示。例如，在本标准中，LFL是最低go和最高no go浓度的计算平均值，而欧洲试验方法将LFL报告为5个最高no go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点出现在可燃性下限的狭窄浓度范围内，但在上限处，断点不太明显。对于根据 13.1.1 可能具有较大淬火距离且可能难以点燃的材料，如氨和某些卤代烃，这些材料的下限和上限可能不太明显。 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 and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 8 ====== 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 5 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 ).