1.1本规程涵盖了使用带有空气循环的室外玻璃覆盖曝光装置的基本原理和操作程序。本规程仅限于获取、测量和控制暴露条件的程序。附录X1列出了许多暴露程序；然而，本规程并未规定最适合待测材料的暴露条件。 1.2对于直接风化暴露，请参阅规程 G7集团 . 对于没有空气循环的玻璃后面的暴露，请参阅实践 G24集团 . 1.3在部分受控的环境试验条件下，将试样暴露于通过玻璃过滤的太阳辐射中。描述了不同的玻璃类型和操作参数。 1.4特定材料的ASTM方法或规范涵盖了试样制备和结果评估。实践中描述了确定暴露后性质变化和报告这些结果的更具体信息 D5870 , D2244 和试验方法 D523 . 1.5以国际单位制表示的数值应视为标准值。 1.6 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====== 与任何加速试验一样，与在用暴露相比，风化速率的增加取决于材料。根据本规程进行的暴露结果可能与一种材料或产品的实际使用条件的结果具有良好的秩相关性。不应假设其他材料或产品也是如此。最好验证加速暴露试验的能力，以便根据实际使用条件对材料的耐久性进行适当排序。 指导 G141页 提供有关使用秩相关的信息。 当操作条件在本规程的可接受范围内变化时，结果可能会发生变化。因此，除非附有符合报告第8节规定的详细说明具体操作条件的报告，否则不得参考使用本规程的结果。 由于太阳辐射、水分、热量、污染物和其他因素的差异，材料在室外使用的耐久性可能会因暴露位置的不同而大不相同。因此，不能假设在单个位置暴露的结果将有助于确定不同位置材料的耐久性排名。 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，并应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。

1.1 This practice covers the basic principles and operating procedures for using outdoor glass-covered exposure apparatus with air circulation. This practice is limited to the procedures for obtaining, measuring and controlling conditions of exposure. A number of exposure procedures are listed in Appendix X1; however, this practice does not specify the exposure conditions best suited for the material to be tested. 1.2 For direct weathering exposures, refer to Practice G7 . For exposures behind glass without air circulation, refer to Practice G24 . 1.3 Test specimens are exposed to solar radiation filtered through glass under partially controlled environmental test conditions. Different glass types and operating parameters are described. 1.4 Specimen preparation and evaluation of the results are covered in ASTM methods or specifications for specific materials. More specific information for determining the change in properties after exposure and reporting these results is described in Practices D5870 , D2244 and Test Method D523 . 1.5 The values stated in SI units are to be regarded as standard. 1.6 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 ====== As with any accelerated test, the increase in rate of weathering compared to in-service exposure is material dependent. Results from exposures conducted to this practice may provide good rank correlation to results from actual use conditions for one type of material or product. It should not be assumed that this will be true for other materials or products. It is always best to verify the ability of an accelerated exposure test to properly rank the durability of materials with actual use conditions. Guide G141 provides information about using rank correlation. Variation in results may be expected when operating conditions are varied within the accepted limits of this practice. Therefore, no reference shall be made to results from the use of this practice unless accompanied by a report detailing the specific operating conditions in conformance with Report Section 8. The durability of materials in outdoor use can be very different depending on the location of the exposure because of differences in solar radiation, moisture, heat, pollutants, and other factors. Therefore, it cannot be assumed that results from exposure in a single location will be useful for determining durability ranking of materials in a different location. 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.