1.1 本规程涵盖了太阳能集热器覆盖材料在高温下暴露于自然气候环境中的程序，该高温近似于太阳能集热箱中的停滞状态，其背部和边缘损失系数组合小于1.5 W/（m 2. ·°C）。 1.2 这种做法适用于玻璃和塑料太阳能集热器盖材料的曝光。规定了单盖和双盖组件的暴露，以适应内外太阳能集热器盖材料暴露的需要。 1.3 本规程不适用于真空集热器、光伏电池、平板集热器的覆盖材料，其背面和边缘损失系数组合大于1。 5 W/（米 2. ·°C）或平板集热器，其设计包含滞止期间限制温度的方法。 1.4 本标准并不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。 1.5 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 本规程描述了风化箱试验夹具，并确定了热损失系数的限值。提供了统一的暴露指南，以尽量减少室外暴露试验中遇到的变量。 4.2 由于高温和太阳辐射的结合可能导致一些太阳能集热器覆盖材料的降解速度比单独暴露更快，因此使用了一个提高覆盖材料温度的风化箱。 4.3 这种做法可用于协助评估停滞模式下的太阳能集热器覆盖材料。任何单一的温度或程序都不能复制停滞状态下覆盖材料可能暴露的温度和环境条件的范围。 为了帮助评估运行模式下的太阳能集热器覆盖材料，实践 E782型 应该使用。现有数据不足，无法获得根据本规程暴露的材料行为与实际使用性能之间的确切相关性。 4.4 这种做法在比较一个场地不同材料的性能或不同场地相同材料的性能时也可能有用，或者两者都有用。 4.5 实践中提供了评估风化影响的方法 E765型 以及评估材料性能的其他ASTM试验方法。 4.6 本实施规程所述类型的暴露可用于评估太阳能集热器覆盖材料在户外暴露于包括天气在内的各种影响时的稳定性。 暴露条件复杂多变。重要因素包括材料温度、气候、一年中的时间、是否存在工业污染等。一般来说，由于难以精确定义或测量影响风化退化的因素，因此室外暴露试验的结果只能作为参考。需要在不同季节进行一年以上的重复暴露试验，以确认任何一个地点的暴露试验。在风化试验中，必须始终使用对照样品进行对比分析。

1.1 This practice covers a procedure for the exposure of solar collector cover materials to the natural weather environment at elevated temperatures that approximate stagnation conditions in solar collectors having a combined back and edge loss coefficient of less than 1.5 W/(m 2 ·°C). 1.2 This practice is suitable for exposure of both glass and plastic solar collector cover materials. Provisions are made for exposure of single and double cover assemblies to accommodate the need for exposure of both inner and outer solar collector cover materials. 1.3 This practice does not apply to cover materials for evacuated collectors, photovoltaic cells, flat-plate collectors having a combined back and edge loss coefficient greater than 1.5 W/(m 2 ·°C), or flat-plate collectors whose design incorporates means for limiting temperatures during stagnation. 1.4 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. 1.5 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 This practice describes a weathering box test fixture and establishes limits for the heat loss coefficients. Uniform exposure guidelines are provided to minimize the variables encountered during outdoor exposure testing. 4.2 Since the combination of elevated temperature and solar radiation may cause some solar collector cover materials to degrade more rapidly than either exposure alone, a weathering box that elevates the temperature of the cover materials is used. 4.3 This practice may be used to assist in the evaluation of solar collector cover materials in the stagnation mode. No single temperature or procedure can duplicate the range of temperatures and environmental conditions to which cover materials may be exposed during stagnation conditions. To assist in evaluation of solar collector cover materials in the operational mode, Practice E782 should be used. Insufficient data exist to obtain exact correlation between the behavior of materials exposed in accordance with this practice and actual in-service performance. 4.4 This practice may also be useful in comparing the performance of different materials at one site or the performance of the same material at different sites, or both. 4.5 Means of evaluating the effects of weathering are provided in Practice E765 , and in other ASTM test methods that evaluate material properties. 4.6 Exposures of the type described in this practice may be used to evaluate the stability of solar collector cover materials when exposed outdoors to the varied influences that comprise weather. Exposure conditions are complex and changeable. Important factors are material temperature, climate, time of year, presence of industrial pollution, etc. Generally, because it is difficult to define or measure precisely the factors influencing degradation due to weathering, results of outdoor exposure tests must be taken as indicative only. Repeated exposure testing at different seasons over a period of more than one year is required to confirm exposure tests at any one location. Control samples must always be used in weathering tests for comparative analysis.