ISO 589:2008

Overview

ISO 589:2008 - Hard coal - Determination of total moisture specifies laboratory procedures to determine total moisture in hard coals. The standard describes two main approaches: a two-stage (Method A) and a single-stage (Method B) moisture determination, each offering a choice of drying in air or drying in a nitrogen atmosphere. ISO 589:2008 establishes controlled drying temperatures, sample preparation and weighing requirements to produce comparable moisture results for coal quality assessment.

Key topics and technical requirements

• Methods covered
  • Method A (two-stage): first-stage air drying at ambient to 30–40 °C, then residual moisture determination after crushing to 2.8 mm and drying at 105–110 °C.
  • Method B (single-stage): crush to nominal top size (11.2 mm or 10 mm) and dry subsamples at 105–110 °C.
• Atmospheres
  • Nitrogen-flushed ovens: recommended for all hard coals; nitrogen quality: oxygen < 30 µl/L; typical flow ~15× oven volume/hour.
  • Air drying: permitted only for coals not susceptible to oxidation (e.g., many high-rank coals such as anthracites).
• Sampling & sample handling
  • Close linkage with mechanical and manual sampling standards to avoid moisture bias during sampling and transport.
  • Precautions against moisture loss: sealed containers, controlled particle-size reduction (prefer crushers), minimize heat and air exposure during handling.
• Apparatus & precision
  • Weighing trays and dishes with specified loading limits (e.g., ≤1 g/cm²; ≤0.3 g/cm² for dishes), balances to 0.1 g and analytical balances to 1 mg, mills that do not heat samples.
  • Typical test portion for residual-moisture determination: about 10 ± 1 g.

Applications and users

ISO 589:2008 is used by:

• Coal testing laboratories performing quality control and contractual analyses.
• Coal producers and traders for reporting moisture content that affects pricing and transport.
• Power plants and industrial users assessing feedstock quality and combustion characteristics.
• Researchers and standards bodies harmonizing moisture measurement procedures.

Practical benefits:

• Ensures repeatable and comparable moisture determination across labs.
• Reduces systematic bias from oxidation or handling loss.
• Supports accurate coal quality assessment, material accounting and compliance testing.

Related standards

• ISO 11722 - Moisture by drying in nitrogen (general analysis sample)
• ISO 13909 (parts 1–4) - Mechanical sampling and sample preparation
• ISO 18283 - Manual sampling
• ISO 1213-2 - Vocabulary for sampling/testing terms

Using ISO 589:2008 helps maintain reliable, standardized moisture data for hard coal quality control and contractual reporting.