Foreword

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This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 4, Sampling.

This third edition cancels and replaces the second edition ( ISO 13909-8:2016 ), which has been technically revised.

The main changes are as follows:

the main title has been modified and aligned with the ISO 13909 series ;
requirements in reference methods have been clarified.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html.

Introduction

It 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 whenever possible and these are discussed in this document.

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.

In 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.

1 Scope

This document sets out principles and procedures for testing the bias of test samples of coals or cokes, taken according to the ISO 13909 series .

2 Normative references

3 Terms and definitions

4 Principles

5 Pretest inspection

6 Reference methods

7 Test design

7.1 Choice of test parameters

7.2 Number of paired samples

7.3 Selection of sample pairs

7.4 Choice of fuel for test

7.5 Coke

8 Conduct of the test

8.1 General

8.2 Collection and preparation of test samples

9 Outline of test procedure

9.1 General

9.2 Special precautions for moisture-test samples

9.3 Documentation

10 Statistical analysis and interpretation

10.1 Outline of statistical procedure

10.2 Calculations

11 Test report

Bibliography