1.1 本规程涵盖了在高温下将太阳能集热器覆盖材料暴露于自然天气环境中的程序，该高温近似于太阳能集热器中的停滞条件，其综合背向和边缘损耗系数小于1.5 W/（m） 2. ·°C）。 1.2 本规程适用于玻璃和塑料太阳能集热器盖材料的暴露。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的暴露需要。 1.3 本规程不适用于背面和边缘综合损耗系数大于1.5W/（m）的真空集热器、光伏电池、平板集热器的覆盖材料 2. ·°C）或平板集热器，其设计包括在停滞期间限制温度的方法。 1.4 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。 ====意义和用途====== 4.1 本规程描述了风化箱测试夹具，并确定了热损失系数的极限。提供了统一的暴露指南，以尽量减少室外暴露试验期间遇到的变量。 4.2 由于高温和太阳辐射的结合可能会导致某些太阳能集热器盖材料比单独暴露时降解更快，因此使用了一个风化箱来提高盖材料的温度。 4.3 本规程可用于协助评估停滞模式下的太阳能集热器盖材料。任何单一温度或程序都无法复制停滞条件下覆盖材料可能暴露的温度和环境条件范围。 为了帮助评估运行模式下的太阳能集热器盖材料，请实践 E782 应使用。没有足够的数据来获得根据本规程暴露的材料行为与实际使用性能之间的精确相关性。 4.4 这种做法在比较不同材料在一个场地的性能或同一材料在不同场地的性能或两者的性能时也很有用。 4.5 实践中提供了评估风化影响的方法 E765 ，以及其他评估材料性能的ASTM试验方法。 4.6 本规程中所述类型的暴露可用于评估太阳能集热器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。重要因素是材料温度、气候、一年中的时间、是否存在工业污染等。 通常，由于很难精确定义或测量影响风化降解的因素，因此室外暴露试验的结果只能作为指示性的。需要在不同季节进行一年以上的重复暴露试验，以确认在任何一个位置进行的暴露试验。风化试验中必须始终使用对照样品进行比较分析。

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 and health practices and determine the applicability of regulatory limitations prior to use. ====== 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.