【国外标准】 Standard Guide for Part-Stream Sampling of Coal

5.1 This guide provides instructions for sampling by collecting individual increments from part of a cross section of a moving stream of coal, as opposed to collection of individual increments by removal of a full cross section of material. The use of part-stream sampling, and the detailed procedures for each case, should be agreed upon in advance by all parties concerned. Samples collected by use of this guide are not probability samples. The user is cautioned that samples of this type do not satisfy the minimum requirements for probability sampling and as such cannot be used to obtain any meaningful statistical inferences such as the sampling precision, standard error, or bias.5.2 All parties should be cautioned that manual sampling of coal from a moving stream might not enable sampling of the material that is furthermost from the point of entry into stream by the sampling device.1.1 This guide covers general principles for obtaining a gross sample of coal by taking increments from part of a stream of coal rather than from the entire stream to be sampled. The usefulness of results from this guide will vary greatly depending on such factors as top size of the coal, size consistency of the coal, variability of the coal, and such logistical factors as the flow rate of the coal in process and physical accessibility of the sampling station.1.2 This guide should be used only when it is not possible to use a method of sampling that produces a probability sample.1.3 Sample preparation procedures involving crushing are contained in Practice D2013.1.4 The values stated in SI units are to be regarded as standard. The values in parentheses are for information only.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 requirements 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.