1.1本规程评估了被动通风和非通风外壳中非金属材料对通过玻璃过滤的太阳辐射的电阻。对于强制空气循环的玻璃外壳下的暴露，请参阅实践 G201型 . 1.2对于直接暴露，请参阅实践 G7集团 . 1.3本惯例仅限于进行暴露的方法。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本规程的A类暴露在技术上类似于ISO的方法B 877-2 . 1.6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。 1.7 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和健康实践，并确定监管限制的适用性。 ====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可能会有所不同。结果的变化可以通过以下方面的曝光时间来最小化: 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性能变化。 4.2温度、湿度和大气污染物的变化可能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。不同的材料可能对热、水分和大气污染物具有不同的敏感性，这可能解释了当其他环境条件不同时，暴露于等效太阳辐射暴露的样本排名的差异。 4.3由于安装方法可能会影响试样暴露期间的温度和其他参数，因此应相互了解所考虑的特定暴露试验的安装方法。 4.4各种单强度窗口玻璃在300至350 nm区域的透射率可能存在很大差异。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，透射率百分比范围为84。 9%-88.1%。 6. 4.5日晒后，不同批次玻璃之间的紫外线透射率差异持续存在。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本规程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强烈建议在每次试验中至少暴露一种对照材料。控制材料应具有相似的成分和结构。并进行选择，使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。如果控制材料作为试验的一部分，则应将其用于比较试验材料相对于控制材料的性能。 4.8还有其他标准描述了玻璃过滤日光的暴露。引用的六个标准是 D3424 , D4303 , D6901 ，ISO 105-B01 ，ISO 877-1 ，ISO-877-2 ，AATCC TM 16C . 4.9由于某些材料在暴露过程中可能会放出气体，建议在同一个玻璃柜下同时只暴露类似材料。

1.1 This practice evaluates the resistance of nonmetallic materials to solar radiation filtered through glass in passively ventilated and non-vented enclosures. For exposures in under glass enclosures with forced air circulation, refer to Practice G201 . 1.2 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 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== 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 may differ. The variations in the results may be minimized 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 rate of degradation. Different materials may have different sensitivities to heat, moisture, and atmospheric contaminants, which may explain differences in rankings of specimens exposed to equivalent solar radiant exposure when other environmental conditions vary. 4.3 Since the method of mounting may influence the temperature and other parameters during exposure of the specimen, there should be a mutual understanding as to the method of mounting the specimen for the particular exposure test under consideration. 4.4 There can be large 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 %. 6 4.5 Differences in UV transmittance between different lots of glass persist 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 strongly recommended that at least one control material be exposed with each test. The control material should be of similar composition and construction. 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. If 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 There are other standards which describe exposures to glass filtered daylight. Six cited standards are D3424 , D4303 , D6901 , ISO 105-B01 , ISO 877-1 , ISO-877-2 , AATCC TM 16C . 4.9 Because of the possibility that certain materials may outgas during exposure, it is recommended that only similar materials be exposed in the same under glass cabinet at the same time.