1.1 这些试验方法包括测定薄膜过滤器上隔离的航空航天流体中颗粒物污染的大小分布和数量。所描述的显微镜技术也可以应用于其他适当制备的小颗粒样品。下面介绍了两种测定颗粒大小的试验方法: 1.1.1 试验方法A-- 颗粒尺寸测量为圆的直径，圆的面积等于颗粒的投影面积。 1.1.2 试验方法B-- 颗粒尺寸是通过其最长尺寸来测量的。 1.2 本试验方法适用于航空航天流体、气体、表面和环境的颗粒污染测定。 1.3 以国际单位制表示的数值应视为标准。 本标准中不包括其他计量单位。 1.4 这些测试方法不提供小于5μm的颗粒尺寸。 注1: 这些方法的结果受制于任何统计方法中固有的变量。除非允许有足够的公差，否则应避免将这些方法用作最初确定限值的标准。 1.5 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。 1.6 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 报告的颗粒尺寸测量是实际颗粒尺寸和形状因子以及被测颗粒的特定物理或化学性质的函数。当比较不同物理或化学参数或不同粒度测量范围的仪器的数据时，需要小心。样品采集、处理和制备也会影响报告的粒度结果。

1.1 These test methods cover the determination of the size distribution and quantity of particulate matter contamination from aerospace fluids isolated on a membrane filter. The microscopical techniques described may also be applied to other properly prepared samples of small particles. Two test methods are described for sizing particles as follows: 1.1.1 Test Method A— Particle sizes are measured as the diameter of a circle whose area is equal to the projected area of the particle. 1.1.2 Test Method B— Particle sizes are measured by their longest dimension. 1.2 The test methods are intended for application to particle contamination determination of aerospace fluids, gases, surfaces, and environments. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 These test methods do not provide for sizing particles smaller than 5 μm. Note 1: Results of these methods are subject to variables inherent in any statistical method. The use of these methods as a standard for initially establishing limits should be avoided unless ample tolerances are permissible. 1.5 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. 1.6 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 Reported particle size measurement is a function of both the actual particle dimension and shape factor, as well as the particular physical or chemical properties of the particle being measured. Caution is required when comparing data from instruments operating on different physical or chemical parameters or with different particle size measurement ranges. Sample acquisition, handling, and preparation can also affect the reported particle size results.