ISO 21398:2019

INTERNATIONAL ISO
STANDARD 21398
Second edition
2019-10
Hard coal and coke — Guidance
to the inspection of mechanical
sampling systems
Houille et coke — Lignes directrices pour l'inspection des systèmes
d'échantillonnage mécanique
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Safety . 1
5 General considerations . 2
5.1 Precision . 2
5.2 Bias . 2
5.3 Operation of sampling system . 2
6 Establishment of inspection system . 2
6.1 General . 2
6.2 Audit — External . 3
6.3 Audit — Internal . 3
6.4 Operational inspections . 3
7 Procedures . 3
7.1 Audit — External . 3
7.2 Audit — Internal . 4
7.3 Operational inspections . 5
8 Quality control . 6
8.1 General . 6
8.2 Sampling ratio . 6
8.3 Coefficient of variation . 6
8.4 Extraction ratio . 7
8.5 Sampling records . 7
8.6 Operators’ inspection report . 7
Annex A (informative) Monitoring coal sampling ratios using control charts.11
Annex B (informative) Examples of sampling checklists .15
Annex C (informative) Example of sampling plant operator’s inspection report .18
Annex D (informative) Examples of sampling plant operations inspection summary.21
Bibliography .23
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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electrotechnical standardization.
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described in the 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
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 27, Solid mineral fuels, Subcommittee
SC 4, Sampling.
This second edition cancels and replaces the first edition (ISO 21398:2007), of which it constitutes a
minor revision. The changes compared to the previous edition are as follows:
— the normative references have been updated and the dates removed;
— the references in Clause 5 have been updated;
— Bibliographic references have been updated.
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.
iv © ISO 2019 – All rights reserved

Introduction
The objective of this document is to provide users of new and existing mechanical sampling systems for
minerals with guidance on their operation and inspection.
An ‘informative’ annex is for information and guidance only.
INTERNATIONAL STANDARD ISO 21398:2019(E)
Hard coal and coke — Guidance to the inspection of
mechanical sampling systems
1 Scope
This document sets out recommended practices for the inspection of mechanical sampling systems. It
serves as a guide for conformance with applicable ISO/TC 27 standards.
This document covers general considerations including precision, mineral variability and bias,
establishment of inspection systems and inspection procedure.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 13909 (all parts), Hard coal and coke — Mechanical sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13909-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
audit
critical review of a mechanical sampling system, which measures its conformance with
stipulated operating specifications, undertaken by a suitably qualified independent person who is not
directly involved in the management of that system
3.2
audit
critical inspection and review of a mechanical sampling system, which measures its
conformance with stipulated operation specifications, undertaken by a suitably qualified person who is
not a day-to-day operator of that particular system
3.3
operational inspection
observations and inspections of operation conditions undertaken by the operator during sampling of a lot
Note 1 to entry: The operator is the person responsible for monitoring the sampling system on a shift-to-shift basis.
4 Safety
This document does not purport to address safety issues that can be associated with its use. It is the
responsibility of the user of this document to establish appropriate safety and health practices in line
with site safety regulations and relevant Occupational Health and Safety Acts. It is highly recommended
that the auditor or inspector start by conducting a careful review of all safety rules and procedures
regarding the sampling system to be inspected.
5 General considerations
5.1 Precision
Precision tests are recommended for each coal or coke type used in the system. If there is a significant
change in a coal or coke type or a new coal or coke type introduced, then a precision test should be
carried out. These tests should be in accordance with ISO 13909-7. The Manager or Supervisor should
maintain a record of the precision of sampling, preparation and analysis of each type of coal and coke
sampled with the system.
5.2 Bias
It is recommended that, after commissioning and auditing of a new system or any major engineering
modifications of an existing system, a bias test be carried out to confirm the system. It is recommended
that the system be verified in accordance with ISO 13909 (all parts) procedures. Reference is made to
ISO 13909-2, and ISO 13909-5, where bias tests may be mandatory under certain conditions. When
choosing a coal or coke type for bias testing, refer to ISO 13909-8. It is recommended that further
bias sample pairs be taken on a regular basis to confirm that the initial bias result is still relevant. If
a significant change is made to the sampling system, or a new mineral having more difficult sampling
characteristics is introduced, a new bias test should be considered.
5.3 Operation of sampling system
The mechanical plant system should be started some time in advance of the start of conveying the coal
or coke so that any foreign substances (including water) are purged. Where hydraulic drives are used,
sufficient time should be allowed for the hydraulic oil and the associated system to attain temperature
equilibrium. It is recommended, particularly in multi-coal or coke sampling systems, that one primary
cut be allowed to pass through the mechanical system as a conditioner before actual sampling
commences.
It is recommended that the operator review any sampling records for the plant maintained by the
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