1.1 本规程涵盖了确定平板太阳能收集器盖板承受冰雹冲击力的能力的程序。推进的冰球被用来模拟冰雹的下落。这种做法并不适用于光伏电池或阵列。 1.2 本规程定义了两种类型的试样，描述了安装试样的方法，规定了每个试样上的冲击位置，提供了确定任何尺寸冰球速度的方程，提供了用冰球冲击试样的方法以及规定了必须记录和报告的参数。 1.3 此做法不确定合格或不合格级别。可接受或不可接受结冰水平的确定- 球的抗冲击能力超出了本练习的范围。 1.4 本规程未规定进行本试验时使用的冰球尺寸。这种做法可以用于各种尺寸的冰球。 1.5 可应用本规程的太阳能集热器盖板材料类别包括: 1.5.1 诸如玻璃的脆性片材， 1.5.2 半刚性薄板，如塑料，以及 1.5.3 柔性薄膜，如塑料薄膜。 1.6 太阳能集热器盖材料应按以下方式进行测试: 1.6.1 组装收集器的一部分（1型试样），或 1.6.2 安装在单独的测试框架盖板支架上（2型试样）。 1.7 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考。 1.8 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。 1.9 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====== 2.1 在许多地理区域，人们担心冰雹对太阳能收集器覆盖物的影响。 这种做法可用于确定平板太阳能收集器盖承受冰雹冲击力的能力。在这种实践中，太阳能收集器盖板承受冰雹冲击的能力与其测试的承受冰球冲击的能力有关。冲击对材料的影响是高度可变的，并且取决于材料。 2.2 本规程描述了安装试样、进行冲击试验和报告影响的标准程序。 2.2.1 提供了安装盖板材料和收集器的程序，以确保它们在与其在太阳能收集器中的使用相关的配置中进行测试。 2.2.2 选择四个冲击的拐角位置来代表盖板上的易受伤害部位。 拐角支撑附近的影响比其他地方的影响更为严重。每个碰撞位置仅指定一个碰撞。出于试验控制的目的，不允许在单个位置进行多次撞击，因为亚临界撞击仍可能造成损坏，从而改变对后续撞击的响应。 2.2.3 合成速度用于模拟冰雹伴随风可能达到的速度。该实践中使用的合成速度是通过将20m/s（45mph）的水平速度与垂直终端速度矢量相加来确定的。 2.2.4 在这种做法中，使用冰球来模拟冰雹，因为天然冰雹不容易使用，而且冰球非常接近冰雹。 然而，尚未确定冰球和冰雹撞击的影响之间的直接关系。冰雹在形状、密度和脆性等特性上变化很大。 2. 这些特性影响诸如传递到盖板的动能、传递能量的周期以及能量分布的区域等因素。冰球的密度、脆弱性和终端速度接近冰雹范围，是目前已知的最接近冰雹的近似值。也许冰球和冰雹之间的主要区别在于冰雹比冰球变化更大。然而，可以均匀地重复制造冰球，以确保具有已知性能的抛射物。 2.2.5 通过冲击各种类型的盖板材料可以产生广泛的可观察效果。影响可能从没有影响到完全破坏不等。当盖板材料没有明显的功能损伤时，可以看到盖板材料的一些变化。报告中必须描述每种影响的所有影响，以便对其重要性进行估计。 2.3 可以使用使用此做法生成的数据:( 1. )为了评估单个材料或收集器的抗冲击性( 2. )为了比较几种材料或收集器的抗冲击性( 3. )为选择在不同地理区域使用的覆盖材料或收集器提供共同基础，或( 4. )以评估由于诸如天气之类的环境因素引起的抗冲击性的变化。 2.4 这种做法没有说明在进行冲击时要使用的冰球的大小。要求测试的人员或执行测试的人员必须确定测试中使用的冰球尺寸。冰球尺寸的选择可能与测试的意图有关。 2.4.1 如果测试是为了评估单个材料或收集器，或几种材料或收集器的抗冲击性，则可能需要使用几种尺寸的冰球重复测试。以这种方式，可以确定各种尺寸的冰球的不同效果。 2.4.2 冰雹的大小和频率在不同的地理区域之间差异很大。如果正在进行测试以评估拟在特定地理区域使用的材料或收集器，则冰球尺寸应与该区域所需的抗冰雹冲击水平相对应。 冰雹大小和频率的信息可以从当地历史天气记录中获得，也可以从 附录X1 . 2.5 材料的抗冰雹冲击性能可能会随着材料暴露于各种环境因素而发生变化。这种做法可用于生成数据，通过比较暴露于这种老化之前和之后测量的抗冰雹冲击数据来评估退化。

1.1 This practice covers a procedure for determining the ability of cover plates for flat-plate solar collectors to withstand impact forces of falling hail. Propelled ice balls are used to simulate falling hailstones. This practice is not intended to apply to photovoltaic cells or arrays. 1.2 This practice defines two types of test specimens, describes methods for mounting specimens, specifies impact locations on each test specimen, provides an equation for determining the velocity of any size ice ball, provides a method for impacting the test specimens with ice balls, and specifies parameters that must be recorded and reported. 1.3 This practice does not establish pass or fail levels. The determination of acceptable or unacceptable levels of ice-ball impact resistance is beyond the scope of this practice. 1.4 The size of ice ball to be used in conducting this test is not specified in this practice. This practice can be used with various sizes of ice balls. 1.5 The categories of solar collector cover plate materials to which this practice may be applied cover the range of: 1.5.1 Brittle sheet, such as glass, 1.5.2 Semirigid sheet, such as plastic, and 1.5.3 Flexible membrane, such as plastic film. 1.6 Solar collector cover materials should be tested as: 1.6.1 Part of an assembled collector (Type 1 specimen), or 1.6.2 Mounted on a separate test frame cover plate holder (Type 2 specimen). 1.7 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.8 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. 1.9 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 ====== 2.1 In many geographic areas there is concern about the effect of falling hail upon solar collector covers. This practice may be used to determine the ability of flat-plate solar collector covers to withstand the impact forces of hailstones. In this practice, the ability of a solar collector cover plate to withstand hail impact is related to its tested ability to withstand impact from ice balls. The effects of the impact on the material are highly variable and dependent upon the material. 2.2 This practice describes a standard procedure for mounting the test specimen, conducting the impact test, and reporting the effects. 2.2.1 The procedures for mounting cover plate materials and collectors are provided to ensure that they are tested in a configuration that relates to their use in a solar collector. 2.2.2 The corner locations of the four impacts are chosen to represent vulnerable sites on the cover plate. Impacts near corner supports are more critical than impacts elsewhere. Only a single impact is specified at each of the impact locations. For test control purposes, multiple impacts in a single location are not permitted because a subcritical impact may still cause damage that would alter the response to subsequent impacts. 2.2.3 Resultant velocity is used to simulate the velocity that may be reached by hail accompanied by wind. The resultant velocity used in this practice is determined by vector addition of a 20 m/s (45 mph) horizontal velocity to the vertical terminal velocity. 2.2.4 Ice balls are used in this practice to simulate hailstones because natural hailstones are not readily available to use, and ice balls closely approximate hailstones. However, no direct relationship has been established between the effect of impact of ice balls and hailstones. Hailstones are highly variable in properties such as shape, density, and frangibility. 2 These properties affect factors such as the kinetic energy delivered to the cover plate, the period during which energy is delivered, and the area over which the energy is distributed. Ice balls, with a density, frangibility, and terminal velocity near the range of hailstones, are the nearest hailstone approximation known at this time. Perhaps the major difference between ice balls and hailstones is that hailstones are much more variable than ice balls. However, ice balls can be uniformly and repeatedly manufactured to ensure a projectile with known properties. 2.2.5 A wide range of observable effects may be produced by impacting the various types of cover plate materials. The effects may vary from no effect to total destruction. Some changes in the cover material may be visible when there is no apparent functional impairment of the cover plate material. All effects of each impact must be described in the report so that an estimate of their significance can be made. 2.3 Data generated using this practice may be used: ( 1 ) to evaluate impact resistance of a single material or collector, ( 2 ) to compare the impact resistance of several materials or collectors, ( 3 ) to provide a common basis for selection of cover materials or collectors for use in various geographic areas, or ( 4 ) to evaluate changes in impact resistance due to environmental factors such as weather. 2.4 This practice does not state the size(s) of ice ball(s) to be used in making the impact. Either the person requesting the test or the person performing the test must determine ice ball size to be used in the testing. Choice of ice ball size may relate to the intent of the testing. 2.4.1 If the testing is being performed to evaluate impact resistance of a single material or collector, or several materials or collectors, it may be desirable to repeat the test using several sizes of ice balls. In this manner the different effects of various sizes of ice balls may be determined. 2.4.2 The size and frequency of hail varies significantly among various geographic areas. If testing is being performed to evaluate materials or collectors intended for use in a specific geographic area, the ice ball size should correspond to the level of hail impact resistance required for that area. Information on hail size and frequency may be available from local historical weather records or may be determined from the publications listed in Appendix X1 . 2.5 The hail impact resistance of materials may change as the materials are exposed to various environmental factors. This practice may be used to generate data to evaluate degradation by comparison of hail impact resistance data measured before and after exposure to such aging.