Foreword

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This document was prepared by Technical Committee ISO/TC 27, Coal and coke, Subcommittee SC 5, Methods of analysis.

This second edition cancels and replaces the first edition ( ISO 23873:2010 ), which has been technically revised.

The main changes are as follows:

clarified units of measure in Figures 1 and 2 and Table 1;
added specifications for temperature recorder;
added balance to Clause 6.

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

The dilatation of coal has been primarily measured by two different standard procedures: the Ruhr dilatometer and the Audibert-Arnu dilatometer. Both methods are very similar, with the same basic apparatus and heating rate, but use different initial masses of coal arising from the method of pencil preparation.

This document combines the two previous procedures by adjusting the equipment specification to define a single acceptable method.

1 Scope

This document describes a method for the measurement of the swelling properties of hard coal using a dilatometer.

2 Normative references

3 Terms and definitions

4 Principle

5 Materials

5.1

5.2

5.3

6 Apparatus

6.1 Mould and accessories

6.2 Dilatometer

6.3 Dilatometer furnace

6.4 Temperature controller

6.5 Temperature recorder

6.6 Retort and piston

6.7 Means of recording piston movement

6.8 Cleaning instruments

6.9 Balance

7 Procedure

7.1 Temperature calibration

7.2 Preparation of test sample and test pieces

7.3 Determination

8 Expression of results

9 Precision

9.1 General

9.2 Repeatability

9.3 Reproducibility

10 Test report

Bibliography

ISO 23873:2025

Hard coal. Method for the measurement of the swelling properties using a dilatometer

Current

Published:

19 Sep 2025

1 Scope