ISO 18123:2023

Overview

ISO 18123:2023 - "Solid biofuels - Determination of volatile matter" specifies a standardized laboratory method to measure the volatile matter of solid biofuels. The volatile matter is defined as the mass loss (excluding moisture) when a test portion of a prepared sample is heated largely out of contact with air under controlled conditions. The standard ensures reproducible results by defining heating rates, final temperature, sample preparation and apparatus requirements.

Key topics and technical requirements

• Test principle: Loss in mass at elevated temperature corrected for moisture; heating largely out of contact with air to avoid oxidation.
• Temperature and time: Test portion heated at 900 °C ± 10 °C for 7 minutes (standardized conditions).
• Sample size and conditioning: Test portion typically 1 g ± 0.1 g from a general analysis sample (nominal top size ≤ 1 mm); moisture is determined concurrently or controlled before testing.
• Apparatus:
  • Electric furnace with a uniform temperature zone and flue/valve to control airflow; temperature recovered within 4 min after insertion of cold stand.
  • Thermocouples: permanently installed sheathed thermocouple plus an unsheathed calibrated thermocouple for calibration checks.
  • Fused silica crucible and well‑fitting lid (crucible mass ~10–14 g; lid-crucible horizontal clearance ≤ 0.5 mm; lids ground to match).
  • Crucible stands (single or multiple) and ceramic supports to achieve the required heating rate.
  • Balance capable of 0.1 mg resolution.
  • Desiccator and controlled desiccant due to hygroscopic ash.
• Procedure controls: Entire procedure must be performed in duplicate; lids and crucible fit are critical to exclude air; automatic equipment is permitted if validated with appropriate biomass reference samples.
• Performance and reporting: Clauses on repeatability, reproducibility and required test report fields ensure traceability and comparability.

Applications and users

ISO 18123:2023 is relevant to:

• Laboratory analysts and quality-control teams measuring biofuel fuel quality.
• Manufacturers and suppliers of solid biofuels (pellets, woodchips, briquettes) for specification and compliance testing.
• Designers and operators of combustion equipment and plants who need volatile matter data for combustion behavior and emissions modelling.
• Traders, purchasers and certifying bodies for contractual specification, acceptance testing and regulatory reporting. Practical uses include fuel acceptance testing, product specification, process control, combustion optimisation and regulatory compliance.

Related standards

• ISO 14780 - Sample preparation for solid biofuels
• ISO 18134‑3 - Moisture content (oven dry method) - general analysis sample
• ISO 18135 - Sampling of solid biofuels
• ISO 21945 - Simplified sampling for small-scale applications
• ISO 16559 - Solid biofuels vocabulary

Keywords: ISO 18123:2023, volatile matter, solid biofuels, biomass testing, crucible, furnace, thermocouple, moisture correction, laboratory method, fuel quality.