1.1本规程提供了在使用实验室光源的加速试验装置中暴露非金属材料时使用的一般程序。有关用于特定设备的程序的详细信息，请参见描述所用特定设备的标准。例如，实践G 152中提供了使用明火碳弧、封闭碳弧、氙弧和荧光紫外光源的设备中曝光的详细信息 ，G 153 ，和G 154 ，和G 155 分别地 笔记 实践23中还描述了1-碳弧、氙弧和荧光紫外线照射 ，G 26 ，和G 53 指的是非常具体的设备设计。实践G 152 ，G 153 ，和G 154 ，和G 155 是否基于性能的标准取代了实践G 23 ，G 26 和G 53。 1.2本规程还描述了用于将非金属材料暴露于实验室光源的装置的一般性能要求。此信息主要用于实验室加速曝光设备的生产商。 1.3本规程提供了加速暴露试验数据的使用和解释信息。关于在暴露前后确定非金属材料性能的方法的具体信息，见描述用于测量每种性能的方法的标准。规程D 5870中描述了有关塑料材料暴露试验结果报告的信息。 笔记 2-导轨G 141 提供了解决非金属材料暴露试验可变性的信息。指南G 169 为暴露测试结果的统计应用提供信息 笔记 3-本标准在技术上等同于ISO 4892第1部分。 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====== 意义 : 在使用实验室光源的设备中进行暴露时，重要的是考虑加速试验条件将如何很好地再现与终端相关的性能变化和故障模式- 测试材料的使用环境。此外，在设置暴露试验和解释加速暴露试验结果时，必须考虑加速试验和室外暴露中的可变性影响。 实验室暴露试验不能指定为室外环境中实际使用条件的完全模拟。只有在确定了所测试的特定材料的秩相关程度并且降解类型相同时，从这些实验室加速暴露中获得的结果才能被视为实际使用暴露的代表。由于紫外线辐射、湿润时间、相对湿度、温度、污染物和其他因素的差异，材料在实际使用条件下的相对耐久性在不同位置可能会有很大差异。 因此，即使根据本规程进行的特定暴露试验的结果有助于比较暴露在特定外部环境中的材料的相对耐久性，也不能假设它们有助于确定相同材料在不同环境中的相对耐久性。 尽管这很诱人，但是 加速系数 有关 x 实验室加速试验中的h或兆焦耳辐射暴露 y 不建议在室外暴露数月或数年。由于几个原因，这些加速系数无效。 加速系数取决于材料，对于每种材料和同一材料的不同配方，加速系数可能会显著不同。 在实际使用和实验室加速暴露试验中，降解速率的变化会对计算的加速因子产生显著影响。 基于实验室光源和太阳辐射之间的辐照度比计算的加速因子，即使使用相同的带通，也不考虑辐照度、温度、湿度以及实验室光源和太阳辐射之间光谱功率分布差异对材料的影响。 笔记 4-如果尽管本规程中给出了警告，但仍需要使用加速因子，则特定材料的此类加速因子仅在其基于足够数量的单独外部和实验室加速暴露的数据时有效，以便可以使用统计方法分析用于将每次暴露中的故障时间关联起来的结果。 J.a.Simms描述了使用多个实验室和外部暴露来计算加速因子的统计分析示例 (1) . 有许多因素可能会降低使用实验室光源的加速试验与外部暴露之间的相关性。关于每个因素如何改变材料稳定性等级的更具体信息，见附录X1。 实验室光源和太阳辐射之间光谱分布的差异。 光强度高于实际使用条件下的光强度。 当实际使用条件提供交替的光照和黑暗时，试样连续暴露在光下的试验条件。 试样温度高于实际条件下的温度。 在浅色和深色样本之间产生不切实际温差的暴露条件。 没有任何温度循环或产生温度循环或热冲击或两者兼有的暴露条件，不代表使用条件。 湿度过高或过低都不切实际。 没有生物制剂或污染物。 使用实验室光源进行加速试验 : 根据本标准进行的加速暴露试验的结果最好用于比较材料的相对性能。一种常见的应用是进行测试，以确定不同批次的质量水平与具有已知性能的对照材料没有差异。 在同一曝光装置中同时测试材料时，最好对材料进行比较。结果可以通过比较将特征特性更改为某个指定水平所需的曝光时间或辐射曝光来表示。 当根据与其他材料或对照物相比的性能排名来评估材料的稳定性时，实验室之间测试结果的再现性已被证明是良好的 , ; 因此，强烈建议在试验材料的同时暴露具有已知性能的类似材料（对照）。 在某些应用中，风化标准物质用于在暴露试验中建立操作条件的一致性。 参考材料，例如蓝色羊毛测试织物，也可用于定时曝光。在某些情况下，标准物质与试验材料同时暴露，并进行暴露，直到标准物质的特性发生规定的变化。然后对试验材料进行评估。在某些情况下，将测试材料的结果与参考材料的结果进行比较。当标准物质对导致试验材料失效的暴露应力不敏感，或当标准物质对对试验材料影响很小的暴露应力非常敏感时，这些是不适当的使用标准物质。 笔记 5-适用于风化试验的控制材料和参考材料的定义见术语G 113。 笔记 6-实践G 156 描述了用于在实验室加速试验中建立操作条件一致性的风化标准物质的选择和表征程序。 笔记 7-当暴露和性能测量程序的可变性已量化，从而可以做出具有统计意义的通过/失败判断时，加速暴露试验的结果仅应用于在特定时间暴露于规定的一组条件后确定材料的通过/失败批准。

1.1 This practice provides general procedures to be used when exposing nonmetallic materials in accelerated test devices that use laboratory light sources. Detailed information regarding procedures to be used for specific devices are found in standards describing the particular device being used. For example, detailed information covering exposures in devices that use open flame carbon arc, enclosed carbon arc, xenon arc and fluorescent UV light source are found in Practices G 152 , G 153 , and G 154 , and G 155 respectively. Note 1—Carbon-arc, xenon arc, and fluorescent UV exposures were also described in Practices 23 , G 26 , and G 53 which referred to very specific equipment designs. Practices G 152 , G 153 , and G 154 , and G 155 are performance based standards that replace Practices G 23 , G 26 , and G 53. 1.2 This practice also describes general performance requirements for devices used for exposing nonmetallic materials to laboratory light sources. This information is intended primarily for producers of laboratory accelerated exposure devices. 1.3 This practice provides information on the use and interpretation of data from accelerated exposure tests. Specific information about methods for determining the property of a nonmetallic material before and after exposure are found in standards describing the method used to measure each property. Information regarding the reporting of results from exposure testing of plastic materials is described in Practice D 5870. Note 2—Guide G 141 provides information for addressing variability in exposure testing of nonmetallic materials. Guide G 169 provides information for application of statistics to exposure test results Note 3—This standard is technically equivalent to ISO 4892, Part 1. 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 ====== Significance : When conducting exposures in devices that use laboratory light sources, it is important to consider how well the accelerated test conditions will reproduce property changes and failure modes associated with end-use environments for the materials being tested. In addition, it is essential to consider the effects of variability in both the accelerated test and outdoor exposures when setting up exposure experiments and when interpreting the results from accelerated exposure tests. No laboratory exposure test can be specified as a total simulation of actual use conditions in outdoor environments. Results obtained from these laboratory accelerated exposures can be considered as representative of actual use exposures only when the degree of rank correlation has been established for the specific materials being tested and when the type of degradation is the same. The relative durability of materials in actual use conditions can be very different in different locations because of differences in UV radiation, time of wetness, relative humidity, temperature, pollutants, and other factors. Therefore, even if results from a specific exposure test conducted according to this practice are found to be useful for comparing the relative durability of materials exposed in a particular exterior environment, it cannot be assumed that they will be useful for determining relative durability of the same materials for a different environment. Even though it is very tempting, calculation of an acceleration factor relating x h or megajoules of radiant exposure in a laboratory accelerated test to y months or years of exterior exposure is not recommended. These acceleration factors are not valid for several reasons. Acceleration factors are material dependent and can be significantly different for each material and for different formulations of the same material. Variability in the rate of degradation in both actual use and laboratory accelerated exposure test can have a significant effect on the calculated acceleration factor. Acceleration factors calculated based on the ratio of irradiance between a laboratory light source and solar radiation, even when identical bandpasses are used, do not take into consideration the effects on a material of irradiance, temperature, moisture, and differences in spectral power distribution between the laboratory light source and solar radiation. Note 4—If use of an acceleration factor is desired in spite of the warnings given in this practice, such acceleration factors for a particular material are only valid if they are based on data from a sufficient number of separate exterior and laboratory accelerated exposures so that results used to relate times to failure in each exposure can be analyzed using statistical methods. An example of a statistical analysis using multiple laboratory and exterior exposures to calculate an acceleration factor is described by J.A. Simms (1) . There are a number of factors that may decrease the degree of correlation between accelerated tests using laboratory light sources and exterior exposures. More specific information on how each factor may alter stability ranking of materials is given in Appendix X1. Differences in the spectral distribution between the laboratory light source and solar radiation. Light intensities higher than those experienced in actual use conditions. Test conditions where specimens are exposed continuously to light when actual use conditions provide alternate periods of light and dark. Specimen temperatures higher than those in actual conditions. Exposure conditions that produce unrealistic temperature differences between light and dark colored specimens. Exposure conditions that do not have any temperature cycling or that produce temperature cycling, or thermal shock, or both, that is not representative of use conditions. Unrealistically high or low levels of moisture. Absence of biological agents or pollutants. Use of Accelerated Tests with Laboratory Light Sources : Results from accelerated exposure tests conducted according to this standard are best used to compare the relative performance of materials. A common application is conducting a test to establish that the level of quality of different batches does not vary from a control material with known performance. Comparisons between materials are best made when they are tested at the same time in the same exposure device. Results can be expressed by comparing the exposure time or radiant exposure necessary to change a characteristic property to some specified level. Reproducibility of test results between laboratories has been shown to be good when the stability of materials is evaluated in terms of performance ranking compared to other materials or to a control , ; therefore, exposure of a similar material of known performance (a control) at the same time as the test materials is strongly recommended. In some applications, weathering reference materials are used to establish consistency of the operating conditions in an exposure test. Reference materials, for example, blue wool test fabric, also may be used for the purpose of timing exposures. In some cases, a reference material is exposed at the same time as a test material and the exposure is conducted until there is a defined change in property of the reference material. The test material then is evaluated. In some cases, the results for the test material are compared to those for the reference material. These are inappropriate uses of reference materials when they are not sensitive to exposure stresses that produce failure in the test material or when the reference material is very sensitive to an exposure stress that has very little effect on the test material. Note 5—Definitions for control and reference material that are appropriate to weathering tests are found in Terminology G 113. Note 6—Practice G 156 describes procedures for selecting and characterizing weathering reference materials used to establish consistency of operating conditions in a laboratory accelerated test. Note 7—Results from accelerated exposure tests should only be used to establish a pass/fail approval of materials after a specific time of exposure to a prescribed set of conditions when the variability in the exposure and property measurement procedure has been quantified so that statistically significant pass/fail judgments can be made.