1.1 这种做法 2 涵盖总样品或分割样品的还原和分割，以及复合样品的制备，包括用于实验室分析的单个部分。 1.2 规定了以下各组煤的还原和分割程序: 1.2.1 A组 包括各种尺寸的清洁煤。 1.2.2 B组 包括所有其他煤。未知煤将在B组下考虑。 1.2.3 A组允许保留比B组更小重量的实验室样本。这些较低的重量可以用于特定的煤，如果它们已经被显示，通过使用以下程序 A1.2 样品制备和分析方差不得过总分析方差的20%。 1.3 单位- 以SI单位或英寸-磅单位表示的值应单独视为标准值。每个系统中陈述的值不一定完全等同；因此，为确保符合标准，每个系统应独立使用，两个系统的数值不得合并使用。 1.4 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。 1.5 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 其他标准品用于收集总样品:实践 D2234/D2234M 允许在破碎前对总样品进行一次分割。使用这些指南和实践收集的总样品或分割样品的质量和顶部尺寸通常太大，无法进行化学或物理测试。实践 D2013/D2013M 提供了通过在线或离线过程或两者将总样品或分割样品减少和分割至适合测试性能的最大尺寸和质量的说明。在遵守本实践之前，总样本或分割样本中的任何偏差将保留在使用本实践产生的最终样本中。什麽什什锦什锦，什切青什锦什锦什锦，什切青什锦什锦什锦，什切青什锦，什锦 5.2 样品的分割和减少可能发生在多于一个位置。最常见的是，通过使用机械取样系统收集、减少和分割(一次或多次)样品。剩余的样品可以在现场进一步分割，以便于将其运输到实验室，在那里在分析之前可能发生进一步的还原和分割。 5.3 在某些地方，这种做法需要在随后还原之前风干样品。空气干燥和空气干燥损失测定的程序见试验方法 D3302/D3302M . 5.4 最常见的是，样品被还原并分成分析样品。然而，一些测试可能需要不同质量或顶部尺寸的样品。该程序可用于提供任何质量和大小的样品，从总样品或分开样品到分析样品并包括分析样品。 5.5 如果需要，本实践还规定了如何制备复合样品。

1.1 This practice 2 covers the reduction and division of gross or divided samples, and the preparation of composite samples, up to and including the individual portions for laboratory analysis. 1.2 Reduction and division procedures are prescribed for coals of the following groups: 1.2.1 Group A includes coals that have been cleaned in all sizes. 1.2.2 Group B includes all other coals. Unknown coals are to be considered under Group B. 1.2.3 Group A allows smaller weight laboratory samples to be retained than Group B. These lower weights may be used for particular coals if they have been shown, by using the procedures of A1.2 , to give a sample preparation and analysis variance which is no more than 20 % of the total analysis variance. 1.3 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 are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 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 Other standards are used to collect the gross sample: Practice D2234/D2234M allows for one division of the gross sample before crushing. The mass and top size of the gross or divided sample collected by using these guides and practices are usually too large for chemical or physical testing. Practice D2013/D2013M provides instructions for reducing and dividing the gross or divided sample, by on-line or off-line processes, or both, to a top size and mass suitable to the performance of testing. Any bias in the gross or divided sample before adherence to this practice will remain in the final sample resulting from use of this practice. Therefore, carefully select the standard to be used to collect the gross sample. 5.2 Division and reduction of a sample may occur at more than one location. Most often, the sample is collected, reduced, and divided (one or more times) by use of a mechanical sampling system. The remaining sample may be further divided on-site to facilitate transporting it to the laboratory where further reduction and division likely occurs before analysis. 5.3 In places, this practice requires air drying the sample before subsequent reduction. Procedures for air drying and air-dry loss determination are provided in Test Method D3302/D3302M . 5.4 Most often, samples are reduced and divided to an analysis sample. However, some tests may require a sample of different mass or top size. This procedure may be used to provide a sample of any mass and size consist from the gross or divided sample to, and including, the analysis sample. 5.5 This practice also specifies how to prepare composite samples, if required.