1、Designation: D6543 00 (Reapproved 2012)1Standard Guide tothe Evaluation of Measurements Made by Online CoalAnalyzers1This standard is issued under the fixed designation D6543; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1NOTEEditorial changes were made throughout in March 2013.1. Scope1.1 This guide provides techniques to be used for theevalua
3、tion of the measurement performance of online coalanalyzers.1.2 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 establish appro-priate safety and health practices and determine the applica-b
4、ility of regulatory limitations prior to use.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 Sampleof CoalD4702 Practice for Quality Management of MechanicalCoal Sampling
5、 Systems (Withdrawn 2008)3D6518 Practice for Bias Testing a Mechanical Coal Sam-pling System (Withdrawn 2008)3E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE178 Practice for Dealing With Outlying ObservationsE456 Terminology Relating to Quality and Statistics3. Terminology
6、3.1 Definitions:3.1.1 analyzer system, na coal quality measurement sys-tem which includes an online coal analyzer and which mayinclude one or more stages of a coal-sampling system.3.1.2 calibration, nmathematical modeling of analyzerand comparative coal sampling and analysis data. Factors fromthe mo
7、del are used in the online analyzer control software.3.1.3 Grubbs estimator, nan estimate of the measurementprecision of an online analyzer (1-3).43.1.4 online analyzer, nan analytical tool consisting of aninstrument and systems, which together provide measurements,or estimates, or both, of coal qua
8、lity parameters.3.1.5 outlier, nan extreme value that statistical tests indi-cate to be far enough from other results in a population underconsideration to cause suspicion that the value is not a memberof the population.3.1.6 reference material, nmaterial of stable compositionthat may be used to gen
9、erate static analyzer measurements.3.1.7 reference system, na measurement system used tomeasure the characteristics of a lot of coal that are alsomeasured by an online analyzer, and against which the onlineanalyzer measurements are compared.3.1.8 standardization, ncalibration of an instrument to are
10、ference material using static stability measurements.3.1.9 static stability, nan estimate of the measurementprecision of an instrument obtained on material that is notmoving. The estimate normally is expressed as the standarddeviation and average of the measurements for a given periodof time.3.1.10
11、synchronization error, nan error that occurs fromcomparing measurements made by an online analyzer and areference system that are not measuring exactly the same lotbecause of temporal and/or spatial offsets.4. Summary of Guide4.1 This guide outlines the evaluation of the measurementperformance of an
12、 online analyzer using comparative measure-ments. The comparative test uses a paired comparison ofanalysis from a reference method using ASTM sampling,1This guide is under the jurisdiction of ASTM Committee D05 on Coal andCoke and is the direct responsibility of Subcommittee D05.23 on Sampling.Curre
13、nt edition approved Sept. 1, 2012. Published November 2012. Originallyapproved in 2000. Last previous edition approved in 2006 as D654300(2006).DOI: 10.1520/D6543-00R12E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For An
14、nual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.Copyright
15、 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1sample preparation, and analysis methods for a lot of coal withthe analysis from the online analyzer for the same lot of coal.The data resulting from the comparative test may be evaluatedusing gr
16、aphical and statistical techniques outlined below.4.2 Various techniques are recommended by online analyzermanufacturers for standardization or static testing. Thesetechniques are useful for establishing a benchmark beforeconducting a comparative test. These techniques also may beused as diagnostic
17、tests in accordance with methods recom-mended by online analyzer manufacturers and graphical andstatistical techniques included in this guide.5. Significance and Use5.1 Online analyzers are used to provide quality data on lotsof coal. The resulting quality data are used as a production toolor for so
18、me contractual application. This guide provides meansof evaluating the system and data produced.5.2 The user should become familiar with the documentsterminology and layout. The section on test design and datacollection will provide the means by which all the analysis datawill be gathered. The test
19、design should be carefully consid-ered to assure meeting the users requirements.5.3 The procedures defined in this guide can be used to testthe accuracy and precision of an online analyzer, for accep-tance after its installation, to check precision and accuracyduring routine use (quality control), w
20、hen changes are made tothe system, when the nature of the coal being tested changes,and to determine mathematical factors to be used for calibra-tion of the online analyzer.6. Selection and Conduct of Performance Evaluations6.1 Introduction:6.1.1 Several techniques can be used to evaluate the perfor
21、-mance of an online analyzer. These techniques provide datathat can be evaluated by using the graphical and statisticalmethods described in Section 7 of this guide.6.1.2 At the time of installation, all of the graphical andnumerical methods outlined in this guide may prove useful. Ona routine basis,
22、 conducting any of the instrument stabilitychecks and comparative evaluations that do not disrupt normaloperations may prove useful. Control charts may be applied toall the performance measures that are gathered on a routinebasis, including mean analysis value of reference material,RMSD, etc.6.1.3 I
23、n the event that there is a change to the operationalparameters or the equipment associated with the analyzer or thereference system, comparative checks should be performed. Inaddition to comparative checks, standardization or staticchecks, or both, as recommended by the online analyzermanufacturer
24、may be helpful.6.1.4 Changes in the following may impact performanceevaluations. Coal characteristics, such as particle size, sourceof coal, mining techniques, degree of preparation, and so forth,which if changed from previous test periods and are not in theanalyzer calibration database, may affect
25、analyzer precisionand accuracy:6.1.4.1 Analyzer components;6.1.4.2 Coal-handling system;6.1.4.3 Laboratory services;6.1.4.4 Sampling technique;6.1.4.5 Coal flow rates; and6.1.4.6 Power disturbances.6.2 Static Stability Measurements for BaselineAssessmentA reference material may be used to provide ab
26、aseline assessment of static measurement precision. Thereference material may be used to compare current mean andstandard deviation values with mean and standard deviationvalues, previously collected in the same manner. The resultingcomparative data may be used to assess whether any change inthe mea
27、n or standard deviation of the static measurements maybe attributed to a change in the operating characteristics of theanalyzer, in the absence of the influence of sampling andanalysis.6.2.1 Reference materials may include actual coal in asealed container, cast high-carbon solids, or other materials
28、which may be provided by the analyzer manufacturer. Theprimary characteristic of these materials is that they not besubject to changes in composition.6.2.2 The results of this evaluation can indicate whetheranalyzer performance has significantly degraded or whether ashift may have occurred. If so, i
29、t may be possible to adjust theanalyzer to restore initial performance. If the user wishes onlyto measure current static repeatability, any available coal maybe used in the analysis zone of the analyzer. Note, however,that the actual standard deviation in static repeatability testsmight be influence
30、d by the composition of the coal beingexamined or analyzer factors, such as the strength of theradioactive sources used by the analyzer or condition ofanalyzer electronic components.6.2.3 It is essential that the length of the analysis period bedefined, (for example, 1, 2, or 5 minutes) and be const
31、ant in thestatic stability test. The static standard deviation resulting fromthe static stability test decreases as the length of the analysisperiod increases. Static stability testing may be conducted onthe same day(s) as comparative tests. One type of static testinvolves a comparison of the analyz
32、er to static coal over manyhours.6.3 Comparison of Analyzer System to Reference SystemMeasurements:6.3.1 Once an analyzer installation has been completed andcalibration adjustments have been made, the analyzer ownermay require acceptance testing. Also, the analyzer owner maydecide to relocate the an
33、alyzer. In these cases, comparisonteststhat is, to compare the analyzer system results to conven-tional sampling and analysis techniqueswill provide the usercalibration verification data and/or data that could be used forrecalibration of the analyzer.6.3.2 Depending upon the comparative technique ch
34、osen,there may be need for more than one comparison. Thesecomparisons may be conducted in a batch over several hours ordays or continuously throughout the operational life of theanalyzer system.6.3.3 If two independent conventional coal-sampling andlaboratory analysis measurements can be made from e
35、ach of aseries of batches of coal interrogated by the analyzer, methodsdeveloped by Grubbs (1-3) can be used to provide unbiasedD6543 00 (2012)12estimates of the measurement precision of the analyzer and ofthe conventional sampling and analysis methods.6.3.4 Any two series of measurements are indepe
36、ndent iftheir measurement errors are uncorrelated. Correlation ofmeasurement errors can be avoided and independence assuredby use of a true random selection of physical increments orsamples of material or by using different schemes and equip-ment for collection, preparation, and laboratory analysis
37、of thesamples, or both. A complete treatment of the subject ofindependence of measurements and the various means ofassuring independence is beyond the scope of this guide.6.4 Sampling Considerations:6.4.1 Selection of Appropriate Sampling and Sample Prepa-ration MethodsThe following increment collec
38、tion methods(see Test Methods D2234/D2234M) are listed in general orderof preference; this preference is not rigid. Often, practicalconsiderations may supercede increment selection decisions.The method to be used for sample preparation should bedetermined before the beginning of increment collection
39、.Sample preparation techniques should remain consistent (seeMethod D2013). Before installation of the analyzer, consider-ation should be given to the ability to obtain representativesamples for comparison to analyzer measurements and theregimen for sample handling and analysis. For the use ofmechani
40、cal sampling systems, inspection (see Guide D4702)and bias testing (see Practice D6518) are good methods forevaluation of the systems suitability for the test.6.4.1.1 Full Stream CutsWhenever possible, the fullstream cut method of increment collection should be used inthe evaluation of an online ana
41、lyzer. This is imperative fordrawing inference using statistical techniques.6.4.1.2 Stopped Belt CutAlthough using “stopped belt”increments allows drawing statistical inferences from the data,the stopped belt increment has limited applicability in theevaluation of online analyzers. This especially i
42、s true incollection of a sample from the lot interrogated by an analyzeroperating in conjunction with a mechanical sampling system.The stopped belt increment may have applicability in instancesin which the analyzer is used in conjunction with mechanicalsampling, and the discharge of the analyzer may
43、 be meteredonto a belt that is subject to stopping without interference withthe analyzers operation. The stopped belt increment may beuseful in evaluating analyzers that are not associated withmechanical sampling and that are being evaluated for veryshort-term performance, that is, less than 1-min r
44、esults. In suchinstances, each stop of the belt is used to collect a sample froma relatively long portion of the belt. As an example, theanalyzer might collect data for 30 s and the belt stopped in sucha manner as to allow access to the entire segment of materialinterrogated by the analyzer (typical
45、ly, 300 ft for a belt running600 ft/min for 30 s). A sample may now be collected byremoving increments from the stopped belt throughout theentire stopped portion. This method reduces the number of beltstops required to assemble a database but is limited inapplicability by the short analysis time and
46、 physical require-ments of the facility wherein the equipment is installed.Nevertheless, this technique may be considered when noreliable mechanical technique is available and the alternative isa manual part stream cut.6.4.1.3 Part Stream IncrementsThis mode of sample col-lection may be required in
47、the evaluation of analyzers notassociated with mechanical sampling or in some tests in whichmore than one comparison will be made. Since this type ofsample does not allow statistical inferences to be drawn in arigorous manner, its use is discouraged. Indeed, the only use ofthis type of comparison mi
48、ght be for control charting purposesrelative to an historical reference.6.4.2 Selection of Reference Sample Point(s):6.4.2.1 Comparative tests can be used to evaluate theperformance of either the analyzer itself or the “analyzersystem” (consisting of the analyzer and the sampling systemthat feeds it
49、). The comparative evaluations of the analyzersystem can be used to determine the ability of the analyzersystem to measure the characteristics of the main coal stream.The selection of the reference system sample point(s) deter-mines whether the comparative tests will assess the analyzer orthe analyzer system.6.4.2.2 The most direct and practical two-instrument test,when the analyzer is fed the secondary reject of a mechanicalsampling system, uses the final save to compare directly to theanalyzer. A manual or mechanical sample collected from theanalyzer discha
