1、Designation:D 4915 96Standard Guide forManual Sampling of Coal from Tops of Railroad Cars1This standard is issued under the fixed designation D 4915;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number i
2、n parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.INTRODUCTIONObtaining a sample of a single lot of coal from railcars that is acceptably representative of the lotfrom which it was taken may present some uni
3、que problems.Factors such as variations in railcarloading equipment and procedures,lack of access to predictable portions of coal in railcars,time,weather,and the heterogeneous nature of the product can all interact,inducing unacceptable bias andvariance in the sample.Therefore,considering the afore
4、mentioned and considering the sample onlyrepresents the top layer of coal in the railroad car,this sampling guide should not be considered as asubstitute for a more reliable sampling method,for example,full stream mechanical sampling.Nonetheless,some laboratory measurement of a lot of coal is often
5、required,so sampling proceduresfor coal in railcars must be designed which reduces variance to an acceptable level while remainingphysically and economically feasible.The procedures described herein are designed to provide guidelines for meeting this criteria.As acaution,however,it is highly recomme
6、nded that any modification in sampling procedure beaccompanied by an understanding of both the product and potential effects of sample interactions withthose modifications.1.Scope1.1 This guide describes manual sampling procedures forcoal contained in railroad cars.These procedures are used toprovid
7、e samples for general analysis and for the determinationof total moisture.The gross sample is to be crushed and furtherprepared for analysis in accordance with Method D 2013 andTest Methods D 2234.1.2 This guide provides instructions for sampling only thetop 18 to 24 in.of a railcar.The user is caut
8、ioned that samplesso obtained do not represent material below the point ofpenetration.1.3 The user is cautioned that,during the removal ofincrements,spillage of coal from the sampling device is to beavoided.Spillage can result in a size biasing of the varioussizes in the coal.1.4 The samples obtaine
9、d by this practice under ConditionD(from stationary sources,see Test Methods D 2234),shall beconsidered less representative than samples taken from thesame lot under Conditions A,B,or C(Test Methods D 2234).1.5 The quantities stated in either acceptable SI units or ininch-pound units shall be regard
10、ed separately as standard.Thequantities stated in each system may not be exact equivalents;therefore,each system must be used independently of the other,without combining quantities in any way.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It i
11、s theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 431 Test Method for Designating the Size of Coal fromits Sieve Analysis2D 2013 Met
12、hod of Preparing Coal Samples for Analysis3D 2234 Test Methods for Collection of a Gross Sample ofCoal3E 105 Practice for Probability Sampling of Materials4E 177 Practice for Use of the Terms Precision and Bias inASTM Test Methods43.Terminology3.1 Definitions3.1.1 accuracy:3.1.1.1 generally,a term u
13、sed to indicate the reliability of asample,a measurement,or an observation.3.1.1.2 specifically,a measure of closeness of agreement1This practice is under the jurisdiction of ASTM Committee D-5 on Coal andCoke and is the direct responsibility of Subcommittee D05.23 on Coal Sampling.Current edition a
14、pproved Oct.10,1996.Published December 1996.Originallypublished as D 4915 89.Last previous edition D 4915 89(1996)e1.2Discontinued;see 1988 Annual Book of ASTM Standards,Vol 05.05.3Annual Book of ASTM Standards,Vol 05.05.4Annual Book of ASTM Standards,Vol 14.02.1Copyright ASTM International,100 Barr
15、 Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.between an experimental result and the true value.An exampleis the observed and true sulfur content of a coal consignment.This measure is affected by chance errors as well as by bias.3.2 analysis samplefinal subsample prepared f
16、rom theoriginal gross sample but reduced to 100%through a No.60(250-m)sieve and divided to not less than 50 g.3.3 angle of reposethe greatest angle,measured fromhorizontal,attained by a coal so that material on the sides ortop of the inverted cone or trench created in car top samplingremains stable(that is,will not shift or slide).Coal size andmoisture content are contributing factors to this angle.In allcases,the coal shall be dug so that the physical angle is lessthan the angle of repose.3.4 b