1.1 本规程涵盖了一种设备和程序，用于制作粉末样品的多个样本，如果粉末是通过流态化机制分离的，则应彼此不同。 1.2 将粉末样品流态化，然后在关闭流态化气体后，将其分离为三个或三个以上的样品，以分析相关参数。试样之间这些参数的差异表明了粉末的偏析潜力。 1.3 粉末必须能够流态化，以便通过本规程进行测试。 1.4 温度和湿度敏感的粉末可能需要在不同的温度和水分含量下进行测试，就像在工业环境中一样。 1.5 本标准不适用于所有散装固体和偏析机制:虽然流态化是许多细粉末经历的常见偏析机制，但本标准未评估的其他偏析机制在实践中可能会导致偏析。 实践 D6940 介绍了另一种常见的机制:筛选。 1.6 在工业情况下，分离的程度不仅取决于粉末及其分离趋势，还取决于处理设备（例如，料仓设计）、工艺（例如，转移速率）和环境。 1.7 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.8 本实践提供了一组用于执行一个或多个特定操作的说明。本文件不能取代教育或经验，应与专业判断一起使用。并非本惯例的所有方面都适用于所有情况。本ASTM标准不代表或取代必须根据其判断给定专业服务的充分性的谨慎标准，也不应在不考虑项目的许多独特方面的情况下应用本文件。 本文件标题中的“标准”一词仅表示该文件已通过ASTM共识程序获得批准。 1.9 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、健康和环境实践，并确定监管限制的适用性。 1.10 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 流化分离可能导致用于容纳和运输粉末的料仓内出现垂直分离。 这可能会影响产品质量或工业应用中的后续过程。 5.2 通过测量粉末的偏析趋势，可以将结果与已知历史的其他粉末进行比较，或者确定给定粉末在给定过程中是否有偏析趋势。 5.3 细粉末的渗透性通常低于粗块状固体，因此倾向于保持空气更长时间。因此，当料仓充满可流化粉末时，较粗的颗粒沉降或被打入床层，而较细的颗粒在表面附近保持流化。 5.4 当细粉末以气动方式输送到料仓、料仓以高速填充或排出、或料仓内存在与粉末流动相反的足够气流时，可能会发生流化，流化是这种分离机制的驱动力。 注1: 该实践产生的结果的质量取决于执行该实践的人员的能力，以及所用设备和设施的适用性。符合实践标准的机构 D3740 通常认为能够胜任和客观的测试/采样/检查等。本规程的用户应注意遵守规程 D3740 本身并不能保证可靠的结果。可靠的结果取决于许多因素；实践 D3740 提供了一种评估其中一些因素的方法。 实践 D3740 是为从事土壤和岩石测试和/或检查的机构开发的。因此，它并不完全适用于执行这种做法的机构。然而，这种做法的用户应该认识到，实践框架 D3740 适用于评估执行此实践的机构的质量。 目前，还没有已知的合格国家机构来检查执行这种做法的机构。

1.1 This practice covers an apparatus and procedure for creating several specimens of a powder sample that, if the powder is one that segregates by the fluidization mechanism, should be different from one another. 1.2 A powder sample is fluidized then, after the fluidizing gas is turned off, it is separated into three or more specimens that can be analyzed for parameters of interest. The difference in these parameters between the specimens is an indication of the segregation potential of the powder. 1.3 Powders must be capable of being fluidized in order to be tested by this practice. 1.4 Temperature- and moisture-sensitive powders may need to be tested at different temperatures and moisture contents, as would happen in an industrial environment. 1.5 This standard is not applicable to all bulk solids and segregation mechanisms: while fluidization is a common segregation mechanism experienced by many fine powders, other segregation mechanisms not evaluated by this standard might induce segregation in practice. Practice D6940 covers another common mechanism: sifting. 1.6 The extent to which segregation will occur in an industrial situation is not only a function of the powder and its tendency to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.8 This practice offers a set of instructions for performing one or more specific operations. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word Standard in the title of this document means only that the document has been approved through the ASTM consensus process. 1.9 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. 1.10 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 Fluidization segregation can cause vertical segregation within bins used to hold and transport powders. This can affect product quality or subsequent processes in industrial applications. 5.2 By measuring a powder's segregation tendency, one can compare results to other powders with known history, or determine if the given powder may have a tendency to segregate in a given process. 5.3 Fine powders generally have a lower permeability than coarse bulk solids and therefore tend to retain air longer. Thus, when a bin is filled with a fluidizable powder, the coarser particles settle or are driven into the bed while the finer particles remain fluidized near the surface. 5.4 Fluidization, which serves as a driving force for this mechanism of segregation, is likely to occur when fine powders are pneumatically conveyed into a bin, the bin is filled or discharged at high rates, or if sufficient air flow counter to the flow of powder is present within the bin. Note 1: The quality of the result produced by this practice is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this practice are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors. Practice D3740 was developed for agencies engaged in the testing and/or inspection of soil and rock. As such it is not totally applicable to agencies performing this practice. However, users of this practice should recognize that the framework of Practice D3740 is appropriate for evaluating the quality of an agency performing this practice. Currently there is no known qualifying national authority that inspects agencies that perform this practice.