1.1 使用太阳作为光源的菲涅耳反射集中器用于材料的加速室外暴露试验。 1.2 本规程涵盖了使用菲涅耳反射镜加速室外风化试验机对材料进行加速室外暴露试验的程序。仪器（见 图1 和 图2 )本文描述了将室外加速暴露试验期间遇到的变量降至最低的指南。 1.3 本规程未规定最适合待测试材料的暴露条件，但仅限于获取、测量和控制暴露程序和某些条件的方法。 特定材料的现有方法或规范涵盖了样品制备、测试条件和结果评估。 1.4 所述菲涅耳反射镜加速室外暴露试验机可能适用于测定暴露在阳光、热量和水分下的材料的相对耐久性，前提是控制材料加速因子的化学或物理变化机制或两者都没有显著差异。 1.5 本规程建立了统一的样品安装和- 测试维护程序。实践中还包括机器和菲涅耳反射镜的维护标准规定，以确保清洁度和耐用性。 1.6 本规程适用于尺寸符合中所述目标板尺寸的试样 8.2 . 1.7 对于当前使用的试验机，本规程可能不适用于超过13 mm的试样( 1. / 2. 英寸。）因为冷却可能有问题。 1.8 以国际单位制表示的数值应视为标准。 括号中的英寸-磅单位仅供参考。 1.9 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。 1.10 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====== 4.1 从该实践中获得的结果可用于比较受所用特定试验循环影响的材料的相对耐久性。只有在确定了所测试的特定材料的比较性能程度后，才能将从本实践中获得的结果视为自然风化的代表。 4.2 加速暴露中的降解速率与自然风化暴露中的降解速率之间的加速系数因材料的类型和配方而异。 每种材料和配方可能对辐照度的增加以及温度和湿度的差异作出不同的反应。因此，为一种材料确定的加速度系数可能不适用于其他材料。因此，不建议使用单一加速度系数。此外，通过使用不同的反射镜类型和配置，可以获得不同的加速因子。由于加速和自然风化暴露试验结果的可变性，必须获得足够数量的试验结果，以确定材料的加速系数。 此外，加速因子仅适用于一个暴露位置，因为自然风化的结果将因气候因子的季节或年度差异而变化。 4.3 通过本规程确定的材料相对耐久性可用于确定在自然风化条件下暴露的材料的相对耐久性，前提是材料具有类似的加速因子。然而，即使发现特定加速试验条件的结果有助于比较暴露在特定外部位置的材料的耐久性，也不能假设它们有助于确定不同位置的相对耐久性。 由于重要气候因素（如阳光、湿润时间、温度、污染物等）的差异，材料在自然风化暴露中的相对耐久性可能会因暴露位置而大不相同。 4.4 当操作条件在本规程的限制范围内变化时，结果可能会发生变化。例如，在相同持续时间或暴露周期数下进行的单独（尽管假设相同）暴露之间，单个材料的降解量可能存在很大差异。 本规程最适用于比较在同一菲涅耳反射装置中同时测试的材料的相对性能。由于同一类型的暴露装置之间可能存在差异，以及不同时间的辐照度、温度和湿度水平的差异，因此不建议比较暴露在相同持续时间内的材料的降解量或在不同时间的辐射能。 4.5 除非与同时暴露的对照材料进行性能比较，否则不应使用本规程在特定暴露期后确定材料的“合格/不合格”批准。 强烈建议每次试验至少暴露一个对照试样。最好使用两个对照试样，一个具有相对良好的耐久性，另一个具有相对较差的耐久性。或者，可以定义测试中的可变性，以便做出具有统计意义的通过/失败判断。 4.6 建议使用每个对照试样和每个待评估材料的至少三个副本。参考指南 G169页 用于执行统计分析。

1.1 Fresnel-reflecting concentrators using the sun as source are utilized in the accelerated outdoor exposure testing of materials. 1.2 This practice covers a procedure for performing accelerated outdoor exposure testing of materials using a Fresnel-reflector accelerated outdoor weathering test machine. The apparatus (see Fig. 1 and Fig. 2 ) and guidelines are described herein to minimize the variables encountered during outdoor accelerated exposure testing. 1.3 This practice does not specify the exposure conditions best suited for the materials to be tested but is limited to the method of obtaining, measuring, and controlling the procedures and certain conditions of the exposure. Sample preparation, test conditions, and evaluation of results are covered in existing methods or specifications for specific materials. 1.4 The Fresnel-reflector accelerated outdoor exposure test machines described may be suitable for the determination of the relative durability of materials exposed to sunlight, heat, and moisture, provided the mechanisms of chemical or physical change, or both, which control the acceleration factors for the materials do not differ significantly. 1.5 This practice establishes uniform sample mounting and in-test maintenance procedures. Also included in the practice are standard provisions for maintenance of the machine and Fresnel-reflector mirrors to ensure cleanliness and durability. 1.6 This practice shall apply to specimens whose size meets the dimensions of the target board as described in 8.2 . 1.7 For test machines currently in use, this practice may not apply to specimens exceeding 13 mm ( 1 / 2 in.) in thickness because cooling may be questionable. 1.8 Values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are provided for information only. 1.9 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. 1.10 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 ====== 4.1 Results obtained from this practice can be used to compare the relative durability of materials subjected to the specific test cycle used. Results obtained from this practice can be considered as representative of natural weathering only when the degree of comparative performance has been established for the specific materials being tested. 4.2 The acceleration factor relating the rate of degradation in this accelerated exposure to the rate of degradation in a natural weathering exposure varies with the type and formulation of the material. Each material and formulation may respond differently to the increased level of irradiance and differences in temperature and humidity. Thus an acceleration factor determined for one material may not be applicable to other materials. For this reason, the use of a single acceleration factor is not recommended. Also, a different acceleration factor may be obtained by using different mirror types and configurations. Because of variability in test results for both accelerated and natural weathering exposures, results from a sufficient number of tests must be obtained to determine an acceleration factor for a material. Further, the acceleration factor is applicable to only one exposure location because results from natural weathering will vary due to seasonal or annual differences in climatic factors. 4.3 The relative durability of materials determined by this practice can be used to determine the relative durability of the materials exposed under natural weathering conditions provided the materials have similar acceleration factors. However, even if results from a specific accelerated test condition are found to be useful for comparing the durability of materials exposed in a particular exterior location, it cannot be assumed that they will be useful for determining the relative durability for a different location. The relative durability of materials in natural weathering exposure can be very different depending on the location of the exposure because of differences in important climatic factors, such as sunlight, time of wetness, temperature, pollutants, etc. 4.4 Variations in results may be expected when operating conditions vary within the limits of this practice. For example, there can be large differences in the amount of degradation in a single material between separate, although supposedly identical, exposures carried out for the same duration or number of exposure cycles. This practice is best used to compare the relative performance of materials tested at the same time in the same fresnel reflector device. Because of possible variability between the same type of exposure device and variability in irradiance, temperature and moisture levels at different times, comparing the amount of degradation in materials exposed for the same duration or radiant energy at separate times is not recommended. 4.5 This practice should not be used to establish a “pass/fail” approval of materials after a specific period of exposure unless performance comparisons are made relative to a control material exposed simultaneously. It is strongly recommended that at least one control test specimen be exposed with each test. It is preferable to use two control test specimens, one with relatively good durability and one with relatively poor durability. Alternatively, the variability in the test can be defined so that statistically significant pass/fail judgements can be made. 4.6 The use of at least three replicates of each control test specimen and each material being evaluated is recommended. Consult Guide G169 for performing statistical analysis.