1.1 以太阳为光源的线性菲涅耳反射器聚光器被用于材料的加速户外暴露测试。 1.2 本规程涵盖了使用线性菲涅耳反射器、加速户外风化试验机对材料进行加速户外暴露试验的程序。仪器（参见 图1 和 图2 )并且本文描述了指南以最小化在户外加速暴露测试期间遇到的变量。 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特定条件的方法。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 当材料暴露于集中的阳光、热量和水分时，所描述的线性菲涅耳反射器加速户外暴露测试设备可能适用于确定材料的相对耐久性。 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线性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 本规程应适用于尺寸符合中所述目标板尺寸的试样 8.2 。 1.7 对于目前使用的试验机，不建议对超过13mm的试样采用此做法( 1. / 2. 英寸）的厚度。 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。 1.10 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====== 4.1 从该实践中获得的结果可用于比较经过所用特定试验循环的材料的相对耐久性。任何加速试验都不能被指定为自然或现场暴露的完美模拟。只有当暴露之间存在足够的数学相关性时，从这种实践中获得的结果才能被认为是自然风化的代表。 4.2 将这种加速暴露中的降解速率与自然风化暴露中的退化速率联系起来的加速因子随材料的类型和配方而变化。 每种材料和配方可以对增加的辐照度水平以及温度和湿度的差异做出不同的响应。因此，为一种材料确定的加速度因子可能不适用于其他材料。因此，不建议使用单个加速度系数。此外，可以通过使用不同的反射镜类型和配置来获得不同的加速度因子。由于加速和自然风化暴露的测试结果存在可变性，必须获得足够数量的测试结果，以确定材料的加速系数。此外，加速系数仅适用于一个暴露位置，因为自然风化的结果会因气候因素的季节或年度差异而变化。 4.3 通过该实践确定的材料的相对耐久性可用于确定暴露在自然风化条件下的材料的相关耐久性，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，也不能认为它们有助于确定不同位置的相对耐久性。由于重要气候因素的差异，如阳光、潮湿时间、温度、污染物等，材料在自然风化暴露中的相对耐久性可能因暴露位置而异。 4.4 当操作条件在本规程的限制范围内变化时，可能会出现结果变化。 4.5 这种做法最好用于比较在同一线性菲涅耳反射器装置中同时测试的材料的相对性能。由于同一类型的暴露设备之间可能存在可变性，以及不同时间辐照度、温度和湿度水平的可变性，因此不建议比较在不同时间暴露相同持续时间或辐射能的材料的降解量。 4.6 除非与同时暴露的对照材料进行性能比较，否则不应使用此做法来确定特定暴露期后材料的“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，一个耐久性相对较好，另一个耐久度相对较差。或者，可以定义测试的可变性，以便做出具有统计学意义的合格/不合格判断。 4.7 建议对每个对照试样和被评估的每种材料进行至少三次重复。查阅指南 G169 用于执行统计分析。

1.1 Linear Fresnel reflector 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 linear 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 linear Fresnel reflector accelerated outdoor exposure test apparatus described may be suitable for the determination of the relative durability of materials when these materials are exposed to concentrated sunlight, heat, and moisture. 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 linear 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 is not recommended for specimens exceeding 13 mm ( 1 / 2 in.) in thickness because of specimen cooling. 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. No accelerated test can be specified as a perfect simulation of natural or field exposures. Results obtained from this practice can be considered as representative of natural weathering only when a sufficient magnitude of mathematical correlation exists between exposures. 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. 4.5 This practice is best used to compare the relative performance of materials tested at the same time in the same linear 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 different times is not recommended. 4.6 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. 4.7 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.