1、Designation: D2234/D2234M 10Standard Practice forCollection of a Gross Sample of Coal1This standard is issued under the fixed designation D2234/D2234M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.INTRODUCTIONData obtained from coal samples are used in establishing price, controlling mine and cleaning plantoperations, allocating production cost
3、s, and determining plant or component efficiency. The task ofobtaining a sample of reasonable weight to represent an entire lot presents a number of problems andemphasizes the necessity for using standard sampling procedures.Coal is one of the most difficult of materials to sample, varying in compos
4、ition 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
5、practice gives the overall requirements for the collection of coal samples. The wide varietiesof coal-handling facilities preclude the publication of detailed procedures for every sampling situation.The proper collection of the sample involves an understanding and consideration of the physicalcharac
6、ter of the coal, the number and weight of increments, and the overall precision required.1. Scope1.1 This practice covers procedures for the collection of asample under various conditions of sampling. The sample is tobe crushed and further prepared for analysis in accordance withPractice D2013. Howe
7、ver, the procedures for dividing largesamples before any crushing are given in this practice. For thesampling of coal using mechanical sampling systems seeD7430 Practice for the Mechanical Sampling of Coal.1.2 This practice describes general and special purposesampling procedures for coals (1) by si
8、ze and condition ofpreparation (for example, mechanically cleaned coal or rawcoal) and (2) by sampling characteristics.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachs
9、ystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establ
10、ish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D2013 Practice for Preparing Coal Samples for AnalysisD7430 Practice for Mechanical Sampling of Coal3. Terminology3.1 Definitions of Terms S
11、pecific to This Standard:3.1.1 accuracy:3.1.1.1 generallya term used to indicate the reliability ofa sample, a measurement, or an observation.3.1.1.2 specificallya measure of closeness of agreementbetween an experimental result and the true value. Example:the observed and true sulfur content of a co
12、al consignment.This measure is affected by chance errors as well as by bias.3.1.2 gross samplea sample representing one lot of coaland composed of a number of increments on which neitherreduction nor division has been performed.3.1.3 incrementa small portion of the lot collected by oneoperation of a
13、 sampling device and normally combined withother increments from the lot to make a gross sample.3.1.4 probability samplea sample collected using a sam-pling process such that at each stage of the process, a specifiednon-zero probability of being selected for the sample can be1This practice is under
14、the jurisdiction of ASTM Committee D05 on Coal andCoke and are the direct responsibility of Subcommittee D05.23 on Sampling.Current edition approved Jan. 1, 2010. Published February 2010. Originallyapproved in 1963. Last previous edition approved in 2009 as D2234/D2234 09a.DOI: 10.1520/D2234_D2234M-
15、10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO B
16、ox C700, West Conshohocken, PA 19428-2959, United States.attached to every sampling unit in the lot to be sampled. Givenadequate information about the sample results obtained usingprobability sampling, the probability distribution of samplingerrors can be estimated.3.1.5 samplea quantity of material
17、 taken from a largerquantity for the purpose of estimating properties or composi-tion of the larger quantity.3.1.6 size consistthe particle size distribution of a coal.4. Summary of Practice4.1 The general-purpose sampling procedures are intendedto provide, in 19 of 20 cases, dry ash results that ar
18、e within aninterval of 6110 of the average dry ash results that would beobtained in hypothetical repeated sampling.4.2 Special-purpose sampling procedures apply to the sam-pling of coal when other precision limits are required, or whenother constituents are used to specify precision, or for perfor-m
19、ance tests.4.3 For coals of known size and condition of preparation,tables are given for the determination of the number and weightof increments required for a gross sample for both general andspecial-purpose sampling.4.4 The procedures appear in the following order:Test Method SectionSampling of Co
20、als Based on Size and Condition of Preparation 8.1General-Purpose Sampling Procedure 8.1.1Number and Weight of Increments 8.1.1.2Number of Gross Samples 8.1.1.4Special-Purpose Sampling 8.1.2Number and Weight of Increments 8.1.2.2Number of Gross Samples 8.1.2.3Division of the Gross Samples Before Cru
21、shing 8.2Sampling of Coal for Total Moisture Determination 8.3Types of Moisture Samples 8.3.1Entire Gross Samples 8.3.1.1Special Moisture Subsamples 8.3.1.2Other Subsamples for Moisture Testing 8.3.1.3Special Precautions 8.3.2Weight of Increments 8.3.3Number of Increments 8.3.4Moisture Sampling Base
22、d Only on Size 8.3.4.15. Significance and Use5.1 It is intended that this practice be used to provide asample representative of the coal from which it is collected.Because of the variability of coal and the wide variety ofsampling equipment, caution should be used in all stages ofsampling from syste
23、m specifications and equipment procure-ment to equipment acceptance testing and actually taking thefinal sample.5.2 After further processing (Practice D2013), the samplemay be analyzed for a number of different parameters. Theseparameters may affect the lots value, its ability to meetspecifications,
24、 its environmental impact, as well as otherproperties.6. Increment Collection Classification6.1 The type of selection, the conditions under whichindividual increments are collected, and the method of spacingof increments from the coal consignment or lot are classifiedaccording to the following descr
25、iptions and Table 1. Thesedesignations are to be used for sampling specifications and fordescriptions of sampling programs and sampling equipment.6.2 Types of IncrementsThe types of selection of incre-ments are based on whether or not there is human discretion inthe selection of the pieces of coal o
26、r portions of the coalstream.6.2.1 Type I, in which specific pieces or portions are notsubject to selection on a discretionary basis. This includes thatin which the increment is collected in precise accord withpreviously assigned rules on timing or location that are free ofany bias. Type I selection
27、 increments generally yield moreaccurate results.6.2.2 Type II, in which some measure of human discretion isexercised in the selection of specific pieces of coal or ofspecific portions of the stream, pile, or shipment.6.3 Conditions of Increment CollectionThe conditionsunder which individual increme
28、nts are collected are the con-ditions of the main body of coal relative to the portionwithdrawn. Four conditions are recognized:6.3.1 Condition A (Stopped-Belt Cut), in which a loadedconveyor belt is stopped and a full cross-section cut withparallel sides is removed from the coal stream. The distanc
29、ebetween the parallel faces shall not be less than three times thenormal top size of the coal.6.3.2 Condition B (Full-Stream Cut), in which a full cross-section cut is removed from a moving stream of coal.6.3.3 Condition C (Part-Stream Cut), in which a portion,not a full cross section, is removed fr
30、om a moving stream ofcoal.6.3.4 Condition D (Stationary Coal Sampling), in which aportion of coal is collected from a pile, a rail car, a barge, or ashiphold.6.4 Spacing of IncrementsThe spacing of incrementspertains to the kind of intervals between increments. TwoTABLE 1 Increment Types, Conditions
31、, and SpacingCondition of Increment Collectionfrom the Main Body of CoalTypes of IncrementType INo Human Discretion Is UsedType IIHuman Discretion Is UsedSpacing of Increments Spacing of Increments1. Systematic 2. Random 1. Systematic 2. RandomCondition A, stopped belt cut I-A-1 I-A-2 II-A-1 II-A-2C
32、ondition B, full-stream cut I-B-1 I-B-2 II-B-1 II-B-2Condition C, part-stream cut I-C-1 I-C-2 II-C-1 II-C-2Condition D, stationary sampling I-D-1 I-D-2 II-D-1 II-D-2D2234/D2234M 102spacing methods are recognized: systematic and random.Systematic spacing is usually preferable.6.4.1 Systematic Spacing
33、 1, in which the movements ofindividual increment collection are spaced evenly in time or inposition over the lot.6.4.2 Random Spacing 2, in which the increments arespaced at random in time or in position over the lot.7. Organization and Planning of Sampling Operations7.1 This practice provides defi
34、nitive procedures for thecollection of a gross sample. Parties claiming to use thispractice must adhere to the procedures as set out in thisstandard. If the sampling is not done in accordance with theprocedures set out in this practice then that sample may not besuitable for comparison with a sample
35、 collected by the proce-dures described in this practice. Since it may be impracticableor impossible to take another sample of a given lot of coal it isessential that parties agree on sampling procedures prior toundertaking sampling.7.2 Selection of Appropriate Sampling ProcedureVariations in coal-h
36、andling facilities make it impossible topublish rigid rules covering every sampling situation in com-plete and exact details. Proper sampling involves an under-standing and proper consideration of the minimum number andweight of increments, the size consist of the coal, the conditionof preparation o
37、f the coal, the variability of the constituentsought, and the degree of precision required.7.2.1 Number and Weight of IncrementsThe number andweight of increments required for a given degree of precisiondepends upon the variability of the coal. This variabilityincreases with an increase in free impu
38、rity. A coal high ininherent impurity and with comparatively little free impuritymay exhibit much less variability than a coal with a lowinherent impurity and a relatively high proportion of freeimpurity. For most practical purposes, an increase in the ashcontent of a given coal usually indicates an
39、 increase invariability. It is imperative that not less than the minimumspecified number of increments of not less than the minimumspecified weight be collected from the lot. For Condition D, theincrements shall be of equal weight.7.2.2 Increment Collection Method to Be UsedTo obtaincomplete represe
40、ntation of all sizes, it is most desirable that thesample increments be withdrawn from the full cross section ofthe stream. The best possible increment is a full cross-sectioncut removed from a stopped belt, Classification I-A-1 in Table1. The best possible increment from a flowing stream of coal is
41、one obtained by moving a cutter device entirely across thestream at a uniform speed, the same for each increment, intoone side of the stream and out of the other, without allowingthe receptacle to overflow (Classification I-B-1 in Table 1). Forthe sampling of coal under Classification I-B-I see D743
42、0Practice for the Mechanical Sampling of Coal. Classificationmethods given in Table 1 are listed in order of decreasingreliability. The highest possible classification method, wher-ever feasible, should be used. Details of sampling proceduresshould be agreed upon in advance by all parties concerned.
43、Whenever circumstances dictate utilization of increment col-lection classifications “Condition C” or “Condition D” or“Type II,” details of sampling procedure shall be agreed uponin advance by all parties concerned.7.3 Distribution of IncrementsIt is essential that theincrements be distributed throug
44、hout the lot to be sampled.This distribution is related to the entire volume of the lot, notmerely its surface or any linear direction through it or over it.If circumstances prevent the sampler from applying thisprinciple, the lot is sampled only in part, and the gross sampleis representative only o
45、f this part. The spacing of the incre-ments shall be varied if the possibility exists that incrementcollection may get “in phase” with the sequence of coalvariability. Example: routine sampling of commercial coalfrom a continuous stream (conveyor belt) in which incrementcollection is automatic and i
46、ts sequence coincides with the“highs” or “lows” in the content of fines.7.4 Dimensions of Sampling DeviceThe opening of thesampling device shall be no less than 2.5 times the nominal topsize of the coal and no less than 30 mm 1.25 in. Thesampling device shall be of sufficient capacity to completelyr
47、etain or entirely pass the increment without spillage at themaximum rate of coal flow.7.5 Characteristics and Movement of Sampling DeviceInsampling from moving streams of coal, the sampling deviceshall be designed to collect each increment with no selectiverejection of material by size and with no c
48、ontamination bynonsample material.7.6 Relative Location of Sampling and WeighingIt ispreferable that coal be weighed and sampled at the same time.If there is a lapse in time between these two events, consider-ation should be given by both the purchaser and the seller tochanges in moisture during thi
49、s interval and the consequentshift in relationship of moisture to the true quality of the coalat the instant when ownership of the coal transfers from one tothe other.7.7 Preservation of MoistureThe increments obtainedduring the sampling period shall be protected from changes incomposition as a result of exposure to rain, snow, wind, sun,contact with absorbent materials, and extremes of temperature.The circulation of air through equipment must be reduced to aminimum to prevent both loss of fines and moisture. Samplesin which moisture content is important shall
