1.1 本规程涵盖了使用带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。这种做法仅限于获得、测量和控制暴露条件的程序。中列出了一些暴露程序 附录X1 ;然而，该实践并未规定最适合待测试材料的暴露条件。 1.2 关于直接风化暴露，请参考实践 G7 .对于在没有空气循环的情况下暴露在玻璃后面的情况，请参阅操作规程 G24 . 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。描述了不同的玻璃类型和操作参数。 1.4 试样制备和结果评估包含在特定材料的ASTM方法或规范中。实践中描述了确定暴露后特性变化并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。 1.6 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。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 5.1 与任何加速试验一样，与在役暴露相比，风化率的增加取决于材料。接触该实践的结果可以与一种材料或产品的实际使用条件的结果提供良好的等级相关性。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，以根据实际使用条件对材料的耐久性进行适当排序。 指导 G141 提供了有关使用秩相关性的信息。 5.2 当操作条件在本规程的可接受范围内变化时，可能会出现结果变化。因此，除非附有符合报告章节的详细说明具体操作条件的报告，否则不得提及使用本规程的结果 8. . 5.3 由于太阳辐射、湿度、热量、污染物和其他因素的差异，材料在户外使用的耐久性可能因暴露位置而异。 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等级。 5.4 建议每次试验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，并应选择与测试材料相同的失效模式。优选使用两种控制材料，一种具有相对较好的耐久性，另一种具有比较差的耐久性。 如果将对照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对照的性能。

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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 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 ====== 5.1 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. 5.2 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 . 5.3 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. 5.4 It is 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.