1.1 本规程描述了在被动通风和非通风的外壳中，将各种材料暴露在通过玻璃过滤的日光下的程序。对于强制空气循环的玻璃外壳下的暴露，请参阅实践 G201型 . 1.1.1 本规程不适用于裸金属的腐蚀试验。 1.2 对于直接暴露，请参阅实践 G7集团 . 1.3 这种做法仅限于进行曝光的方法。具体材料的各种标准涵盖了试样制备和结果评估。 1.4 根据本规程进行的曝光可以使用两种类型的曝光柜。 1.4.1 A型- 允许暴露在玻璃后面的样本被动通风的机柜。 1.4.2 B类- 外部漆为黑色的封闭柜，不为暴露在玻璃后面的样本提供通风。使用B型机柜进行的曝光通常被称为“玻璃曝光下的黑匣子” 1.5 这种做法的A类暴露在技术上类似于ISO的方法B 877-2. 1.6 单位- 以国际单位制表示的数值应视为标准值。国际单位制后括号中给出的值仅供参考，不被视为标准值。 1.7 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。 1.8 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 由于太阳辐射、空气温度、相对湿度以及大气污染物的数量和种类不断变化，基于经过的时间的暴露结果有时会有所不同。结果的变化通常会通过以下方面的暴露时间来减少: 4.1.1 一个或多个环境参数，如太阳辐射暴露，或 4.1.2 具有已知性能的风化参考样品的预定义特性变化。 4.2 温度、湿度和大气污染物的变化会对太阳辐射引起的降解产生重大影响。此外，在一年中的不同时间进行的暴露可能会导致降解率的巨大差异。不同的材料通常对热、水分和大气污染物具有不同的敏感性，这可以解释当其他环境条件不同时，暴露在等效太阳辐射暴露下的样本排名的差异。 4.3 由于安装方法对试样暴露期间的温度和其他参数有影响，合同双方应就所考虑的特定暴露试验的安装方法达成一致。 4.4 各种单强度窗口玻璃在300至350 nm区域的透射率存在差异。例如，在320 nm处，七种不同批次的单强度窗玻璃的透射率百分比在8.4%到26.8%之间。在380 nm处，透过率在84.9%到88.1%之间。 5. 4.5 即使在日晒之后，不同批次玻璃之间的紫外线透射率差异通常也会继续存在。窗口玻璃在紫外线透射率方面的最大差异在300至320 nm的光谱范围内。 4.6 这种做法最好用于比较同一批玻璃后同时测试的材料的相对性能。由于大量玻璃之间以及在一年中不同时间进行的暴露之间存在差异，因此不建议比较暴露在相同持续时间内的材料或在不同时间的辐射暴露中，或在使用不同批次玻璃的单独固定装置中的降解量。 4.7 建议在每次试验中至少暴露一种具有已知性能的对照材料。控制材料的成分和结构应与试样相似，并且其选择应确保其失效模式与被测材料的失效模式相同。最好使用两种控制材料，一种具有相对良好的耐久性，另一种具有相对较差的耐久性。当控制材料作为试验的一部分时，应将其用于比较试验材料相对于控制材料的性能。 4.8 由于某些材料在暴露过程中可能会放出气体，并可能污染其他试样，因此建议在同一个玻璃柜下同时只暴露类似材料。

1.1 This practice describes procedures for conducting exposures of various materials to daylight filtered through glass in passively ventilated and non-vented enclosures. For exposures in under glass enclosures with forced air circulation, refer to Practice G201 . 1.1.1 This practice is not intended for corrosion testing of bare metals. 1.2 For direct exposures, refer to Practice G7 . 1.3 This practice is limited to the method of conducting the exposures. The preparation of test specimens and evaluation of results are covered in various standards for the specific materials. 1.4 Exposure conducted according to this practice can use two types of exposure cabinets. 1.4.1 Type A— A cabinet that allows passive ventilation of specimens being exposed behind glass. 1.4.2 Type B— Enclosed cabinet with exterior painted black that does not provide for ventilation of specimens exposed behind glass. Exposures conducted using a Type B cabinet are typically referred to as “black box under glass exposures.” 1.5 Type A exposures of this practice are technically similar to Method B of ISO 877-2. 1.6 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.7 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. 1.8 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 Since solar radiation, air temperature, relative humidity, and the amount and kind of atmospheric contaminants vary continuously, results from exposures based on elapsed time will sometimes differ. The variations in the results will usually be reduced by timing the exposures in terms of: 4.1.1 One or more environmental parameters such as solar radiant exposure, or 4.1.2 A predefined property change of a weathering reference specimen with known performance. 4.2 Variations in temperature, moisture, and atmospheric contaminants can have a significant effect on the degradation caused by solar radiation. In addition, exposures conducted at different times of the year can cause large differences in the rate of degradation. Different materials generally have different sensitivities to heat, moisture, and atmospheric contaminants, and this could explain differences in rankings of specimens exposed to equivalent solar radiant exposure when other environmental conditions vary. 4.3 Since the method of mounting has an influence on the temperature and other parameters during exposure of the specimen, there shall be agreement between contractual parties as to the method of mounting the specimen for the particular exposure test under consideration. 4.4 There are differences among various single strength window glasses in their transmittance in the 300 to 350 nm region. For example, at 320 nm, the percent transmittance for seven different lots of single strength window glass ranged from 8.4 to 26.8 %. At 380 nm, the percent transmittance ranged from 84.9 % to 88.1 %. 5 4.5 Differences in UV transmittance between different lots of glass generally continue even after solarization. The largest differences among window glasses in UV transmittance are in the spectral range of 300 to 320 nm. 4.6 This practice is best used to compare the relative performance of materials tested at the same time behind the same lot of glass. Because of variability between lots of glass and between exposures conducted at different times of the year, comparing the amount of degradation in materials exposed for the same duration or radiant exposure at separate times, or in separate fixtures using different lots of glass, is not recommended. 4.7 It is recommended that at least one control material with known performance be exposed with each test. The control material should be of similar composition and construction as the test specimen, and be chosen so that its failure modes are the same as that of the material being tested. It is preferable to use two control materials, one with relatively good durability, and one with relatively poor durability. When control materials are included as part of the test, they shall be used for the purpose of comparing the performance of the test materials relative to the controls. 4.8 Because of the possibility that certain materials will outgas during exposure and potentially contaminate other specimens, it is recommended that only similar materials be exposed in the same under glass cabinet at the same time.