ISO INTERNATIONAL STANDARD 13909-7 Second edition 2016-07-01 Hard coal and coke Mechanical sampling - Part 7: Methods for determining the precision of sampling, sample preparation and testing Houille et coke-Echantillonnage mécanique - Partie 7: Méthodes pour la détermination de la fidelité de I'échantillonnage, de la preparation de I'échantillon et de I'essai Reference number ISO 13909-7:2016(E) ISO International Organization for Standardization @ IS0 2016 ed without license from IHS IS0 13909-7:2016(E) COPYRIGHT PROTECTED DOCUMENT IS0 2016, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either Iso at the address below or Iso's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org Internatinir DrganizationforStandardization Licensee-ZHEJIANG INST OF STANDARDIZzRoISQ6- All rights reserved Not for Resale, 2016/8/16 08:27:21 No reproduction or networking permited without license from IHS IS0 13909-7:2016(E) Contents Page Foreword ..iv Introduction. .. 1 Scope. ..1 2 Normative references 3 Terms and definitions 4 General. ..1 5 Formulae relating to factors affecting precision .2 5.1 General. .2 5.2 Sampling. .3 6 Estimation of primary increment variance 4 6.1 Direct determination of individual primary increments 4 6.2 Determination using the estimate of precision. .5 7 Methods for estimating precision. 5 7.1 General 5 7.2 Duplicate sampling with twice the number of increments. .5 7.3 Duplicate sampling during routine sampling .8 7.4 Alternatives to duplicate sampling 7.5 Precision adjustment procedure .9 8 Calculation of precision. ..10 8.1 Replicate sampling. 10 8.2 Normal sampling scheme .11 6 Methods of checking sample preparation and testing errors .12 9.1 General. 12 9.2 Target value for variance of sample preparation and analysis .12 9.2.1 General. .12 9.2.2 Off-line preparation. .13 9.2.3 On-line preparation .13 9.3 Checking procedure as a whole 13 9.4 Checking stages separately .14 9.4.1 General. 14 9.4.2 Procedure 1 .15 9.4.3 Procedure 2 18 9.4.4 Interpretation of results 21 9.5 Procedure for obtaining two samples at each stage 22 9.5.1 With ariffle .22 9.5.2 With a mechanical sample divider 22 9.6 Example .22 Annex A (informative) Variogram method for determining variance .26 Annex B (informative) Grubbs' estimators method for determining sampling precision ..34 Bibliography ..43 ii censee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed without license from IHS