1.1 本规程涵盖了通过筛分机制模拟散装固体偏析趋势的装置和程序。 1.2 温度和湿度敏感的散装固体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。 1.3 最大粒径应限制为3 mm[ 1. / 8. 英寸。]，以减少滑动栅极绑定的可能性。 1.4 本标准不适用于所有散装固体和分离机制:虽然筛分是许多散装固体经历的常见分离机制，但本标准未评估的其他分离机制在实践中可能会导致分离。实践 D6941 涵盖另一种常见机制:流态化。 1.5 在工业情况下，分离的程度不仅取决于散装固体及其分离趋势，还取决于搬运设备（例如，料仓设计）、过程（例如，传输速率）和环境。 1.6 单位- 以国际单位制或英寸-磅单位表示的数值应单独视为标准值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.7 所有观察值和计算值应符合实践中确定的有效数字和舍入准则 D6026 . 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 筛分离析可能导致用于容纳和运输散装固体的料仓内出现水平离析（例如，从中心到外围）。这可能会影响工业应用中的最终产品质量或后续过程。 5.2 通过测量散装固体的偏析趋势，可以将结果与具有已知历史的其他散装固体进行比较，或者确定给定的散装固体在给定过程中是否有偏析趋势。 5.3 筛分是一种常见的分离方法，通过筛分过程，较小的颗粒在较大颗粒的基质中移动。筛选必须存在四个条件: 5.3.1 单个组分之间的粒径差异- 该比率可低至1.3:1。一般来说，粒径比越大，颗粒通过筛分分离的趋势越大。 5.3.2 足够大的平均粒径- 平均粒径在50μm范围内时可能发生筛分偏析，如果平均粒径大于100μm，则可能成为主要的偏析机制。 5.3.3 充分自由流动的材料- 这允许较小的颗粒在较大颗粒的基质中筛选。 对于粘性材料，细颗粒相互结合，不会进入粗颗粒之间的空隙。 5.3.4 粒子间运动- 这可能是由于桩的形成、振动或流动材料的速度梯度引起的。 5.4 这四个条件都必须存在，才能发生筛选分离。如果不存在这些条件中的任何一种，材料将不会通过这种机制分离。 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 simulating the segregation tendencies of bulk solids by means of the sifting mechanism. 1.2 Temperature- and humidity-sensitive bulk solids may need to be tested at different temperatures and moisture contents, as would happen in an industrial environment. 1.3 The maximum particle size should be limited to 3 mm [ 1 / 8 in.], to reduce the likelihood of binding the slide gate. 1.4 This standard is not applicable to all bulk solids and segregation mechanisms: while sifting is a common segregation mechanism experienced by many bulk solids, other segregation mechanisms not evaluated by this standard might induce segregation in practice. Practice D6941 covers another common mechanism: fluidization. 1.5 The extent to which segregation will occur in an industrial situation is not only a function of the bulk solid and its tendency to segregate, but also the handling equipment (for example, bin design), process (for example, transfer rates), and environment. 1.6 Units— The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. 1.7 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 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 Sifting segregation can cause horizontal segregation (for example, center-to-periphery) within bins used to hold and transport bulk solids. This can affect final product quality or subsequent processes in industrial applications. 5.2 By measuring a bulk solid's segregation tendency, one can compare results to other bulk solids with known history, or determine if the given bulk solid may have a tendency to segregate in a given process. 5.3 Sifting, which is a process by which smaller particles move through a matrix of larger ones, is a common method of segregation. Four conditions must exist for sifting to occur: 5.3.1 A Difference in Particle Size between the Individual Components— This ratio can be as low as 1.3 to 1. In general, the larger the ratio of particle sizes, the greater the tendency for particles to segregate by sifting. 5.3.2 A Sufficiently Large Mean Particle Size— Sifting segregation can occur with a mean particle size in the 50 μm range and can become a dominant segregation mechanism if the mean particle size is above 100 μm. 5.3.3 Sufficiently Free Flowing Material— This allows the smaller particles to sift through the matrix of larger particles. With cohesive materials, the fine particles are bound to one another and do not enter the voids among the coarse particles. 5.3.4 Interparticle Motion— This can be caused during formation of a pile, by vibration, or by a velocity gradient across the flowing material. 5.4 All four of these conditions must exist for sifting segregation to occur. If any one of these conditions does not exist, the material will not segregate by this mechanism. 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.