ASTM D6543-00(2012)
(Guide)Standard Guide to the Evaluation of Measurements Made by On-Line Coal Analyzers
Standard Guide to the Evaluation of Measurements Made by On-Line Coal Analyzers
SIGNIFICANCE AND USE
5.1 On-line analyzers are used to provide quality data on lots of coal. The resulting quality data are used as a production tool or for some contractual application. This guide provides means of evaluating the system and data produced.
5.2 The user should become familiar with the document's terminology and layout. The section on test design and data collection will provide the means by which all the analysis data will be gathered. The test design should be carefully considered so as to assure meeting the user's requirements.
5.3 The procedures defined in this guide can be used to test the accuracy and precision of an on-line analyzer, for acceptance after its installation, to check precision and accuracy during routine use (quality control), when changes are made to the system, when the nature of the coal being tested changes, and to determine mathematical factors to be used for calibration of the on-line analyzer.
SCOPE
1.1 This guide provides techniques to be used for the evaluation of the measurement performance of on-line coal analyzers.
1.2 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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D6543 − 00(Reapproved 2012)
Standard Guide to
the Evaluation of Measurements Made by On-Line Coal
Analyzers
This standard is issued under the fixed designation D6543; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.2 calibration, n—mathematical modeling of analyzer
and comparative coal sampling and analysis data. Factors from
1.1 This guide provides techniques to be used for the
the model are used in the on-line analyzer control software.
evaluation of the measurement performance of on-line coal
3.1.3 Grubbs estimator, n—an estimate of the measurement
analyzers.
precision of an on-line analyzer (1-3).
1.2 This standard does not purport to address all of the
3.1.4 on-line analyzer, n—an analytical tool consisting of an
safety concerns, if any, associated with its use. It is the
instrumentandsystems,whichtogetherprovidemeasurements,
responsibility of the user of this standard to establish appro-
or estimates, or both, of coal quality parameters.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. 3.1.5 outlier, n—an extreme value that statistical tests indi-
cate to be far enough from other results in a population under
2. Referenced Documents consideration to cause suspicion that the value is not a member
of the population.
2.1 ASTM Standards:
3.1.6 reference material, n—material of stable composition
D121 Terminology of Coal and Coke
that may be used to generate static analyzer measurements.
D2013 Practice for Preparing Coal Samples for Analysis
D2234/D2234M Practice for Collection of a Gross Sample
3.1.7 reference system, n—a measurement system used to
of Coal
measure the characteristics of a lot of coal that are also
D4702 Practice for Quality Management of Mechanical
measuredbyanon-line-analyzer,andagainstwhichtheon-line
Coal Sampling Systems (Withdrawn 2008)
analyzer measurements are compared.
D6518 Practice for Bias Testing a Mechanical Coal Sam-
3.1.8 standardization, n—calibration of an instrument to a
pling System (Withdrawn 2008)
reference material using static stability measurements.
E177 Practice for Use of the Terms Precision and Bias in
3.1.9 static stability, n—an estimate of the measurement
ASTM Test Methods
precision of an instrument obtained on material that is not
E178 Practice for Dealing With Outlying Observations
moving. The estimate normally is expressed as the standard
E456 Terminology Relating to Quality and Statistics
deviation and average of the measurements for a given period
of time.
3. Terminology
3.1.10 synchronization error, n—an error that occurs from
3.1 Definitions:
comparing measurements made by an on-line analyzer and a
3.1.1 analyzer system, n—a coal quality measurement sys-
reference system that are not measuring exactly the same lot
tem which includes an on-line coal analyzer and which may
because of temporal and/or spatial offsets.
include one or more stages of a coal-sampling system.
4. Summary of Guide
4.1 This guide outlines the evaluation of the measurement
This guide is under the jurisdiction of ASTM Committee D05 on Coal and
performance of an on-line analyzer using comparative mea-
Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.
surements. The comparative test uses a paired comparison of
Current edition approved Sept. 1, 2012. Published November 2012. Originally
analysis from a reference method using ASTM sampling,
approved in 2000. Last previous edition approved in 2006 as D6543–00(2006).
DOI: 10.1520/D6543-00R12.
sample preparation, and analysis methods for a lot of coal with
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
the analysis from the on-line analyzer for the same lot of coal.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
The last approved version of this historical standard is referenced on The boldface numbers in parentheses refer to the list of references at the end of
www.astm.org. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6543 − 00 (2012)
The data resulting from the comparative test may be evaluated 6.1.4.5 Coal flow rates; and
using graphical and statistical techniques outlined below. 6.1.4.6 Power disturbances.
4.2 Various techniques are recommended by on-line ana-
6.2 Static Stability Measurements for Baseline
lyzer manufacturers for standardization or static testing. These Assessment—A reference material may be used to provide a
techniques are useful for establishing a benchmark before
baseline assessment of static measurement precision. The
conducting a comparative test. These techniques also may be reference material may be used to compare current mean and
used as diagnostic tests in accordance with methods recom- standard deviation values with previous mean and standard
mended by on-line analyzer manufacturers and graphical and deviation values, previously collected in the same manner. The
statistical techniques included in this guide. resulting comparative data may be used to assess whether any
change in the mean or standard deviation of the static mea-
5. Significance and Use
surements may be attributed to a change in the operating
5.1 On-line analyzers are used to provide quality data on
characteristics of the analyzer, in the absence of the influence
lots of coal. The resulting quality data are used as a production
of sampling and analysis.
tool or for some contractual application. This guide provides
6.2.1 Reference materials may include actual coal in a
means of evaluating the system and data produced.
sealed container, cast high-carbon solids, or other materials
which may be provided by the analyzer manufacturer. The
5.2 The user should become familiar with the document’s
primary characteristic of these materials is that they not be
terminology and layout. The section on test design and data
subject to changes in composition.
collectionwillprovidethemeansbywhichalltheanalysisdata
6.2.2 The results of this evaluation can indicate whether
will be gathered. The test design should be carefully consid-
analyzer performance has significantly degraded or whether a
ered so as to assure meeting the user’s requirements.
shift may have occurred. If so, it may be possible to adjust the
5.3 The procedures defined in this guide can be used to test
analyzer to restore initial performance. If the user wishes only
the accuracy and precision of an on-line analyzer, for accep-
to measure current static repeatability, any available coal may
tance after its installation, to check precision and accuracy
be used in the analysis zone of the analyzer. Note, however,
during routine use (quality control), when changes are made to
that the actual standard deviation in static repeatability tests
the system, when the nature of the coal being tested changes,
might be influenced by the composition of the coal being
and to determine mathematical factors to be used for calibra-
examined or analyzer factors, such as the strength of the
tion of the on-line analyzer.
radioactive sources used by the analyzer or condition of
analyzer electronic components.
6. Selection and Conduct of Performance Evaluations
6.2.3 It is essential that the length of the analysis period be
6.1 Introduction:
defined, for example, 1, 2, or 5 min, and be constant in the
6.1.1 Several techniques can be used to evaluate the perfor-
static stability test.The static standard deviation resulting from
mance of an on-line analyzer. These techniques provide data
the static stability test decreases as the length of the analysis
that can be evaluated by using the graphical and statistical
period increases. Static stability testing may be conducted on
methods described in Section 7 of this guide.
the same day(s) as comparative tests. One type of static test
6.1.2 At time of installation, all of the graphical and
involves a comparison of the analyzer to static coal over many
numerical methods outlined in this may prove useful. On a
hours.
routine basis, conducting any of the instrument stability checks
6.3 Comparison of Analyzer System to Reference System
and comparative evaluations that do not disrupt normal opera-
Measurements:
tionsmayproveuseful.Controlchartsmaybeappliedtoallthe
6.3.1 Once an analyzer installation has been completed and
performance measures that are gathered on a routine basis, for
example, mean analysis value of reference material, RMSD, calibration adjustments have been made, the analyzer owner
may require acceptance testing. Also, the analyzer owner may
and so forth.
6.1.3 In the event that there is a change to the operational decide to relocate the analyzer. In these cases, comparison
tests, that is, to compare the analyzer system results to
parametersortheequipmentassociatedwiththeanalyzerorthe
conventional sampling and analysis techniques, will provide
reference system, comparative checks should be performed. In
addition to comparative checks, standardization or static the user calibration verification data and/or data that could be
used for recalibration of the analyzer.
checks, or both, as recommended by the on-line analyzer
manufacturer may be helpful. 6.3.2 Depending upon the comparative technique chosen,
6.1.4 Changes in the following may impact performance there may be need for more than one comparison. These
evaluations. Coal characteristics, such as particle size, source comparisonsmaybeconductedinabatchoverseveralhoursor
of coal, mining techniques, degree of preparation, and so forth, days or continuously throughout the operational life of the
which if changed from previous test periods and are not in the analyzer system.
analyzer calibration database, may affect analyzer precision 6.3.3 If two independent conventional coal-sampling and
and accuracy: laboratory analysis measurements can be made from each of a
6.1.4.1 Analyzer components; series of batches of coal interrogated by the analyzer, methods
6.1.4.2 Coal-handling system; developed by Grubbs (1-3) can be used to provide unbiased
6.1.4.3 Laboratory services; estimates of the measurement precision of the analyzer and of
6.1.4.4 Sampling technique; the conventional sampling and analysis methods.
D6543 − 00 (2012)
6.3.4 Any two series of measurements are independent if 6.4.1.3 Part Stream Increments—This mode of sample col-
their measurement errors are uncorrelated. Correlation of lection may be required in the evaluation of analyzers not
associated with mechanical sampling or in some tests in which
measurement errors can be avoided and independence assured
by use of a true random selection of physical increments or more than one comparison will be made. Since this type of
sample does not allow statistical inferences to be drawn in a
samples of material or by using different schemes and equip-
rigorous manner, its use is discouraged. Indeed, the only use of
ment for collection, preparation, and laboratory analysis of the
this type of comparison might be for control charting purposes
samples, or both. A complete treatment of the subject of
relative to an historical reference.
independence of measurements and the various means of
6.4.2 Selection of Reference Sample Point(s):
assuring independence is beyond the scope of this guide.
6.4.2.1 Comparative tests can be used to evaluate the
6.4 Sampling Considerations:
performance of either the analyzer itself or the “analyzer
6.4.1 Selection of Appropriate Sampling and Sample Prepa-
system” (consisting of the analyzer and the sampling system
ration Methods—The following increment collection methods
that feeds it). The comparative evaluations of the analyzer
(see Test Methods D2234/D2234M) are listed in general order
system can be used to determine the ability of the analyzer
of preference; this preference is not rigid. Often, practical
system to measure the characteristics of the main coal stream.
considerations may supercede increment selection decisions. The selection of the reference system sample point(s) deter-
The method to be used for sample preparation should be
mines whether the comparative tests will assess the analyzer or
determined before the beginning of increment collection. the analyzer system.
Sample preparation techniques should remain consistent (see 6.4.2.2 The most direct and practical two-instrument test,
Method D2013). Before installation of the analyzer, consider- when the analyzer is fed the secondary reject of a mechanical
ation should be given to the ability to obtain representative sampling system, uses the final save to compare directly to the
analyzer. A manual or mechanical sample collected from the
samples for comparison to analyzer measurements and the
regimen for sample handling and analysis. For the use of analyzer discharge may provide an independent sample, which
may be used to assess the performance of the analyzer (see
mechanical sampling systems, inspection (see Guide D4702)
Figs. 1-3).
and bias testing (see Practice D6518) are good methods for
6.4.2.3 There are instances when there is no save sample
evaluation of the system’s suitability for the test.
(see Fig. 4) associated with the system feeding the analyzer. In
6.4.1.1 Full Stream Cuts—Whenever possible, the full
this case, it is possible to construct a test with several
stream cut method of increment collection should be used in
comparisons by collecting separate samples from the analyzer
the evaluation of an on-line analyzer. This is imperative for
feed and discharge. Since independence of the samples is
drawing inference using statistical techniques.
important for three instrument evaluations, subsequent prepa-
6.4.1.2 Stopped Belt Cut—Although using “stopped belt”
ration and analyses should be performed at different times by
increments allows drawing statistical inferences from the data,
different parties.
the stopped belt increment has limited applicability in the
6.4.2.4 In some instances, the discharge of the analyzer may
evaluation of on-line analyzers. This especially is true in
be fed to further stages of mechanical sampling.Asingle stage
collection of a sample from the lot interrogated by an analyzer
of sampling downstream of the analyzer is most common (see
operating in conjunction with a mechanical sampling system.
Fig. 5). In this case, the secondary save will provide a
The stopped belt increm
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.