1、Designation: D7430 14D7430 15Standard Practice forMechanical Sampling of Coal1This standard is issued under the fixed designation D7430; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenth
2、eses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONAnalysis data obtained from coal samples are used in establishing price, controlling mine andcleaning plant operations, allocating production costs, and
3、 determining plant or component efficiency.The task of obtaining a sample of reasonable weightmass to represent an entire lot presents a numberof problems and emphasizes the necessity for using standard sampling procedures.Coal is one of the most difficult of materials to sample, varying in composit
4、ion from noncombus-tible particles to those which can be burned completely, with all gradations in between. The task isfurther complicated by the use of the analytical results, the sampling equipment available, the quantityto be represented by the sample, and the degree of precision required.This pr
5、actice gives the overall requirements for the collection and within-system preparation of coalsamples through the use of mechanical sampling systems utilizing falling stream, cross belt and augerdesigns. This practice also gives the overall requirements for the bias testing and quality managementof
6、mechanical coal sampling systems. The wide varieties of coal-handling facilities preclude thepublication of detailed procedures for every sampling situation. The proper collection of the sampleinvolves an understanding and consideration of the physical character of the coal, the number andweightmass
7、 of increments, and the overall precision required.1. Scope1.1 This practice is divided into 4 parts. These 4 parts represent the previous standards D7256/D7256M, D4916, D4702, andD6518. These 4 standards are the 4 that govern the mechanical sampling of coal and have been combined into one document
8、forthe ease of reference of the users of these standards.Part A1.2 Part AMechanical Collection and Within-System Preparation of a Gross Sample of Coal from Moving StreamsCoversprocedures for the mechanical collection of a sample under Classification I-B-1 and I-B-2 (Practice D2234/D2234M) and thewit
9、hin-system preparation (reduction and division) of gross samples utilizing various components of the mechanical samplingsystem.1.2.1 Part A describes mechanical sampling procedures for coals (1) by size and condition of preparation (for example,mechanically cleaned coal or raw coal), and (2) by samp
10、ling characteristics.1.2.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may resul
11、t in non-conformance with the standard.Part B1.3 Part BMechanical Auger SamplingDescribes procedures for the collection of an increment, partial sample, or grosssample of material using mechanical augers. Reduction and division of the material by mechanical equipment at the auger is alsocovered. Fur
12、ther manual or mechanical reduction or division of the material elsewhere shall be performed in accordance withPractice D2013.1.3.1 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1 This practice is under the jurisdiction of A
13、STM Committee D05 on Coal and Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved May 15, 2014Feb. 1, 2015. Published May 2014April 2015. Originally approved in 2008. Last previous edition approved 20132014 asD743013.14. DOI: 10.1520/D7430-14.10.1520/D74
14、30-15.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult pri
15、or editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Part C1.4 Part CQuality Management of Mech
16、anical Coal Sampling SystemsIs applicable to the quality management ofcross-belt, falling stream, and auger sampling systems.1.4.1 Spacing of increments pertains to the kind of interval between increments. Intervals can be defined in quantitative terms,such as units of time or mass, or in terms of p
17、osition over the lot.1.4.2 Spacing of Increments for Cross-Belt and Falling Stream SamplersCross-belt and falling stream type mechanicalsampling systems take increments based on time, either at fixed time intervals or at random times during a fixed time strata. Somefalling stream samplers can take i
18、ncrements based on equal mass of coal sampled as determined by scales. The sections of thispractice that pertain to cross-belt and falling stream samplers describe procedures for only time-based sampling systems. Thistime-based inspection guideline will satisfy most criteria for mass-based or combin
19、ation mass-based and time-based samplingsystems. If there are items that are not covered, the inspector should refer to the manufacturers literature.1.4.3 Spacing of Increments for Auger SamplingThe spacing of increments collected by auger sampling systems is definedin terms of position over the lot
20、.1.4.4 It is essential that the inspector have the documentation listed in Section 2 of this practice when conducting an inspection.1.4.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.Part D1.5 Part DBias Testing of a Mechan
21、ical Coal Sampling SystemPresents sample collection and statistical evaluationprocedures for testing mechanical sampling systems (including auger systems), subsystems, and individual system components forbias. It is the responsibility of the user of this practice to select the appropriate procedure
22、for a specific sampling situation.1.5.1 Part D does not purport to define an absolute bias. Bias defined by this practice is the difference between the populationmean of the mechanical sampler test results and the accepted reference value.1.5.2 The values stated in SI units are to be regarded as sta
23、ndard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the ap
24、plicability of regulatorylimitations prior to use. For a specific hazard statement, see section 16.1.2. Referenced Documents2.1 ASTM Standards:2D121 Terminology of Coal and CokeD2013 Practice for Preparing Coal Samples for AnalysisD2234/D2234M Practice for Collection of a Gross Sample of CoalD4621 G
25、uide for Quality Management in an Organization That Samples or Tests Coal and Coke (Withdrawn 2010)3D4702 Practice for Quality Management of Mechanical Coal Sampling Systems (Withdrawn 2008)3D4749 Test Method for Performing the Sieve Analysis of Coal and Designating Coal SizeD4916 Practice for Mecha
26、nical Auger Sampling (Withdrawn 2008)3D6518 Practice for Bias Testing a Mechanical Coal Sampling System (Withdrawn 2008)3D7256/D7256M Practice for Mechanical Collection and Within-System Preparation of a Gross Sample of Coal from MovingStreams (Withdrawn 2008)3E105 Practice for Probability Sampling
27、of MaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an
28、 Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 DefinitionsDefinitions applicable to this practice are listed in Terminology D121.3.2 Definitions of Terms Specific to This Standard:3.2.1 accuracy, n(1)generally, a term used to indicate the reliability of a sample,
29、 a measurement, or an observation;(2)specifically, a measure of closeness of agreement between an experimental result and the true value.An example is the observedand true sulfur content of a coal consignment. This measurement is affected by chance errors as well as by bias.3.2.2 activation interval
30、, nfor a falling-stream or cross-belt cutter, the time from the beginning of movement for taking anincrement, to the beginning of movement for taking of the next increment.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Ann
31、ual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.D7430 1523.2.3 auger increment, nthe retained portion of one extraction operation of the auger.3.2.4 au
32、ger sampler, na mechanical device that extracts a columnar sample of coal from a railcar, truck, barge or stockpileand any associated sub-system or within-system components.3.2.5 bias, nthe difference between the population mean of the mechanical sampler test results and the accepted referencevalue.
33、3.2.6 confidence interval, na numeric interval with a lower limit and a higher limit within which the true parameter value isestimated to fall. The confidence interval percentage indicates the percentage of time the true value will fall within the interval ifthe procedure is continuously repeated.3.
34、2.7 consignment, na discrete amount of coal, such as a shipment, a car load, a unit train, or a days production. Aconsignment may include more than one lot of coal and may correspond to a specific period of time, such as a sampling periodor a billing period.3.2.8 correlation, na measure of the linea
35、r dependence between paired system and reference measurements. Correlationfrequently is expressed by the correlation coefficient, which can take a value from minus one (perfect negative linear relationship)to plus one (perfect positive linear relationship).3.2.9 cross-belt sampler, na single samplin
36、g machine or component of a mechanical sampling system designed to extract anincrement directly from a conveyor belt surface by sweeping a sampling device (cutter) through the material on the conveyor.3.2.10 delimitation error, na material error that occurs when all the elements in a cross section o
37、f a coal stream do not havean equal probability of being intercepted (captured) by the sampler cutter during increment collection.3.2.11 ellipsoidal region, nan area that is formed by plane sections of ellipses that are defined by the values selected for thelargest tolerable bias of each coal charac
38、teristic used in the bias test. The region will be used to determine if the system is biased.3.2.12 falling-stream sampler, na single sampling machine or component of a mechanical sampling system designed to extractan increment from a falling stream of coal at the discharge end of a conveyor or chut
39、e by moving a sampling device (cutter) throughthe falling stream of material.3.2.13 Hotellings T2 test, na statistical test that is used to evaluate multivariate data. It is the multivariate equivalent of theStudents t-test.3.2.14 largest tolerable bias (LTB), nan interval whose upper and lower boun
40、ds represent the limits of an acceptable bias.3.2.15 mechanical sampling system, na single machine or series of interconnected machines whose purpose is to extractmechanically, or process (divide and reduce), or a combination thereof, a sample of coal.3.2.16 paired data set, nsystem and reference va
41、lues observed on samples collected and compared from the same batch ofmaterial.3.2.17 precision, na term used to indicate the capability of a person, an instrument, or a method to obtain reproducible results;specifically, a measure of the chance error as expressed by the variance, standard error, or
42、 a multiple of the standard error (seePractice E177).3.2.18 reference sample, na sample used in testing of a mechanical sampling system which is comprised of one or moreincrements collected from the test batch or lot of coal by the stopped belt method as described in Practice D2234/D2234M.3.2.19 rej
43、ect stream, nthe coal flow within a mechanical sampling system, which occurs at each stage of division, before andafter reduction, and is not included in the system sample.3.2.20 sampling ratio, nthe mass of the system sample divided by the mass of the corresponding coal sampled.3.2.21 save stream,
44、nthe coal flow within a mechanical sampling system which occurs at each stage of division, before andafter reduction, and after the final stage of division becomes the system sample.3.2.22 statistical independence, ntwo sample values are statistically independent if the occurrence of either one in n
45、o wayaffects the probability assigned to the occurrence of the other.3.2.23 surrogate sample, na sample, used in the evaluation of a mechanical sampling system, which is comprised of one ormore increments collected from a coal stream within the mechanical sampling system in accordance with Practice
46、D2234/D2234M,Conditions “A” or “B.” Such a sample may be considered acceptable for evaluation of a mechanical sampling systemscomponents, excluding the primary cutter, when demonstrated to be equivalent to the reference sample.3.2.24 system sample, na sample collected from a test batch or lot of coa
47、l by the final stage of a mechanical sampling system.3.2.25 unbiased sample (representative sample), na sample free of bias.3.2.26 Walsh averages, ngiven a series of observations (differences) x1, x2, . xn, the n (n + 1)/2 pair-wise averages givenby:xi1xj!/2,1#i#j#n (1)D7430 1533.2.26.1 DiscussionAs
48、 an example of Walsh averages, assume one has three observations (differences) designated as x1, x2, and x3. There are thena total of 3(4)/2 = 6 Walsh averages. They are as follows: x1, x2, x3, (x1 + x2)/2, (x1 + x3)/2, and (x2 + x3)/2.3.2.27 Wilcoxon Signed Rank Test, na non-parametric statistical
49、procedure for calculating the point estimate and confidenceinterval for a sample drawn from a population with symmetric distribution.3.2.28 within-system preparation, nthe process of gross sample preparation carried out mechanically by sequential crushing(reduction) equipment and/or division equipment. It may be carried out by processing increments individually or by batchingincrements together and processing them together as a group. In any case, within-system preparation is conducted in a manner tominimize moisture changes and wit
