1、BS ISO 13909-8:2016Hard coal and coke Mechanical samplingPart 8: Methods of testing for biasBSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06BS ISO 13909-8:2016 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 13909-8:2016. It sup
2、ersedes BS ISO 13909-8:2001 which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee PTI/16, Solid mineral fuels.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all t
3、he necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2016.Published by BSI Standards Limited 2016ISBN 978 0 580 83181 2 ICS 73.040; 75.160.10 Compliance with a British Standard cannot confer immunity from legal obligations.This B
4、ritish Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2016.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 13909-8:2016 ISO 2016Hard coal and coke Mechanical sampling Part 8: Methods of testing for biasHouille et
5、coke chantillonnage mcanique Partie 8: Mthodes de dtection du biaisINTERNATIONAL STANDARDISO13909-8Second edition2016-07-01Reference numberISO 13909-8:2016(E)BS ISO 13909-8:2016ISO 13909-8:2016(E)ii ISO 2016 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2016, Published in SwitzerlandAll rights
6、 reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from eith
7、er ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 13909-8:2016ISO 13909-8:2016(E)Foreword ivIntroduction v1 Scope
8、 . 12 Normative references 13 Terms and definitions . 14 Principles . 15 Pretest inspection . 26 Reference methods 27 Test design 37.1 Choice of test parameters 37.2 Number of paired samples 37.3 Selection of sample pairs . 37.3.1 Composition of sample pairs . 37.3.2 Paired-increment samples. 47.3.3
9、 Paired-batch samples . 47.4 Choice of fuel for test . 47.5 Coke 48 Conduct of the test 48.1 General . 48.2 Collection and preparation of test samples 59 Outline of test procedure . 59.1 General . 59.2 Special precautions for moisture-test samples . 69.3 Documentation . 610 Statistical analysis and
10、interpretation 610.1 Outline of statistical procedure 610.2 Calculations 710.2.1 Statistical procedure for identifying outliers 710.2.2 Disposition of outliers . 810.2.3 Calculation of confidence intervals and determining bias . 810.2.4 Review of the 95 % confidence region for the bias .1211 Test re
11、port 12Annex A (informative) Example calculations13Bibliography .28 ISO 2016 All rights reserved iiiContents PageBS ISO 13909-8:2016ISO 13909-8:2016(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work
12、 of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmen
13、tal, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the
14、ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possib
15、ility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of
16、patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as i
17、nformation about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 27, Solid mineral fuels, Subcommittee SC 4, Sampling.This second edition cancels and replac
18、es the first edition (ISO 13909-8:2001), which has been technically revised.ISO 13909 consists of the following parts, under the general title Hard coal and coke Mechanical sampling: Part 1: General introduction Part 2: Coal Sampling from moving streams Part 3: Coal Sampling from stationary lots Par
19、t 4: Coal Preparation of test samples Part 5: Coke Sampling from moving streams Part 6: Coke Preparation of test samples Part 7: Methods for determining the precision of sampling, sample preparation and testing Part 8: Methods of testing for biasiv ISO 2016 All rights reservedBS ISO 13909-8:2016ISO
20、13909-8:2016(E)IntroductionIt is not possible to lay down a standard method for field work by which a sampling procedure can be tested for bias because details of the procedure will inevitably be affected by local conditions. However, certain principles can be specified which ought to be adhered to
21、whenever possible and these are discussed in this part of ISO 13909.Testing for bias can be a tedious and expensive process. All bias tests therefore include a thorough pretest inspection, with appropriate action taken regarding any system deficiencies likely to cause bias. ISO 2016 All rights reser
22、ved vBS ISO 13909-8:2016BS ISO 13909-8:2016Hard coal and coke Mechanical sampling Part 8: Methods of testing for bias1 ScopeThis part of ISO 13909 sets out principles and procedures for testing the bias of test samples of hard coals or cokes, taken in accordance with other parts of ISO 13909.NOTE In
23、 the text, the term “fuel” is used where both coal and coke would be applicable in the context and either “coal” or “coke” where only one is applicable.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its applic
24、ation. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 13909-1, Hard coal and coke Mechanical sampling Part 1: General introductionISO 13909-4, Hard coal and coke Mechanical sampling Pa
25、rt 4: Coal Preparation of test samplesISO 13909-6, Hard coal and coke Mechanical sampling Part 6: Coke Preparation of test samplesISO 13909-7, Hard coal and coke Mechanical sampling Part 7: Methods for determining the precision of sampling, sample preparation and testingISO 21398, Hard coal and coke
26、 Guidance to the inspection of mechanical sampling systems3 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 13909-1 apply.4 PrinciplesThe testing of a sampling system for bias is based on taking a series of pairs of samples of essentially the same fuel;
27、 one member of each pair being sampled by the system or component under test, the other member being obtained by a reference method. For each pair, the difference between the analytical results is determined. The series of differences between the analytical results thus obtained are subjected to sta
28、tistical analysis.The sensitivity of the statistical test is dependent on the number of pairs compared, the variability of the differences between members of the pairs, and the number of parameters used for the test.The statistical analysis to which results will be subjected assumes the following th
29、ree conditions: a multivariate normal distribution of the variables; independence of the errors of measurement for the individual parameters; homogeneity of the data.INTERNATIONAL STANDARD ISO 13909-8:2016(E) ISO 2016 All rights reserved 1BS ISO 13909-8:2016ISO 13909-8:2016(E)5 Pretest inspectionThe
30、 primary sources of information regarding compliance with the sampling standard are the equipment specifications and drawings.A thorough examination of the sampling system and a review of its component specification shall be made (see ISO 21398).The party performing the test shall, however, verify p
31、erformance by field measurements and observations. The operation of the sampling system shall be observed both dynamically with fuel flowing and statically with no fuel flowing. Some components will need to be actuated in static mode.Pretest inspections of all operations and equipment, both static a
32、nd under load, should be carried out by persons experienced in the sampling of segregated, heterogeneous, and lumpy bulk materials. It is recommended that operation under normal conditions be observed for an entire lot.Do not execute a test for bias until all conditions known to cause bias are corre
33、cted unless it is necessary to establish the performance of a system or component as it stands. In the latter case, the pretest inspection provides essential documentation of what the conditions were at the time of the test.6 Reference methodsTo test overall system bias, the use of a reference metho
34、d which is known to be intrinsically unbiased is required. The preferred method is the stopped-belt method, i.e. the collection of increments from a complete cross-section of the fuel on the conveyor belt by stopping the belt at intervals. When properly collected from the primary fuel stream, the st
35、opped-belt increment can be considered as a reference increment.NOTE If it is not possible to collect stopped-belt increments, other reference methods can be used but, in these cases, an apparent absence of a lack of bias relative to the reference method may not be conclusive and the use of such met
36、hods may compromise the validity and authority of the findings.With collection of stopped-belt increments, some disruption of normal operations can occur, and therefore, the plan of execution may need to be coordinated with the normal operations and organized to minimize such disruption. It should b
37、e recognized that the conveyor system involved may be used for only a few hours per day for normal operations and cannot be operated solely for bias tests unless the fuel can be diverted to another discharge point. This can extend the time necessary for completion of the field work and require speci
38、al arrangements for supplying fuel to the system for testing.Stopped-belt increments shall be taken with a sampling frame (see Figure 1), or equivalent, from a complete cross-section of the solid mineral fuel on the belt at a fixed position, for a length along the belt which is at least three times
39、the nominal top size of the fuel.Figure 1 Sampling frameThe sampling frame (or equivalent) shall be placed on the stationary belt at the predetermined position so that the separator plates at each end are in contact with the belt across its full width. All particles lying inside the sampling frame e
40、nd plates shall be swept into the sampling container.2 ISO 2016 All rights reservedBS ISO 13909-8:2016ISO 13909-8:2016(E)Particles obstructing the insertion of the end plate on the left-hand side shall be pushed into the increment, while those obstructing the insertion of the end plate on the right-
41、hand side shall be pushed out of the increment or vice-versa. Whichever practice is used initially, this practice shall be implemented throughout the test.Care should be taken to minimize the risk of bias being introduced in the course of preparation of the increments and samples and all sample divi
42、sion equipment and procedures should be checked for bias with respect to relevant test parameters.It is recommended that all increments/samples be weighed immediately after collection. Pay close attention to minimizing unintended mass losses.Report all observed mass losses.7 Test design7.1 Choice of
43、 test parametersThe standard test for general purposes shall include moisture and ash (ash on a dry basis). Use of these two parameters will generally suffice. Other variables can be included if desired. However, given a fixed number of sample pairs, the test often becomes less sensitive to detectio
44、n of a bias as additional variables are included.Bias in ash on a dry basis is most commonly caused by errors in size distribution. Bias in moisture content may be caused by a wide variety of factors, including, but not limited to, errors in size distribution, moisture losses associated with crusher
45、s, excessive ventilation within the sampling system, less than the closest possible coupling between system components, excessive retention time in the system, or any combination of these.Direct tests on particle size distribution are often necessary for coke. It is recommended that tests for size d
46、istribution be conducted as a separate test and that size distribution parameters not be included in the standard test for analytical parameters.7.2 Number of paired samplesThe minimum number of paired samples for the test shall be 30. However, if necessary, more sets may be collected if the varianc
47、e of the quality of the fuel is suspected to influence the detection of bias. On the other hand, if use of a smaller number of paired samples results in a detection of bias, no additional samples need be collected. After completing the statistical calculations, the resulting confidence region can be
48、 evaluated. If no bias is detected, yet the confidence region covers levels of bias that are of commercial concern, more paired samples can be collected for coal originating from this same source in order to reduce the size of the confidence region.7.3 Selection of sample pairs7.3.1 Composition of s
49、ample pairsThe members of each pair of samples can each be comprised of portions of one or more increments. Individual increments can be paired or samples of compounded increments can be paired. The test shall be structured so that the expected mean of the differences of the result would be zero if no systematic error is present in the system under test. ISO 2016 All rights reserved 3BS ISO 13909-8:2016ISO 13909-8:2016(E)7.3.2 Paired-increment samplesPaired-increment experimental design is the compar
