ISO 18134-1:2022

Overview

ISO 18134-1:2022 - "Solid biofuels - Determination of moisture content - Part 1: Reference method" specifies a high-precision oven-drying reference method for determining the moisture content of solid biofuels. The standard covers test sample handling, drying conditions, weighing procedures (including buoyancy correction), calculations and reporting. Results are always reported on a wet basis (as received, percentage of total mass). Emissions of volatile organic compounds (VOC) during oven drying are acknowledged but considered negligible for this method.

Key topics and technical requirements

• Drying principle: Dry test portion in air at 105 ± 2 °C until constant mass is achieved.
• Constant mass definition: Mass change not exceeding 0.2% absolute of the initial test portion during a 60-minute heating period.
• Apparatus:
  • Drying oven with uniform temperature and 3–5 air changes per hour; air flow must not dislodge particles.
  • Non-corrodible, heat‑resistant trays with clean even surfaces.
  • Balance readable to 0.1 g.
• Sample preparation:
  • Samples obtained per ISO 18135 or ISO 21945 and reduced to particle sizes per ISO 14780 (particles with at least one dimension < 31.5 mm).
  • Minimum test portion: 300 g (100 g allowed for fine particulates such as sawdust or fuel powder).
  • Warning to avoid moisture gain/loss during handling and size reduction; pre-drying may be required for very wet samples.
• Weighing and buoyancy correction:
  • Weigh tray + test portion before drying and weigh same tray while still hot after drying.
  • Use an identical reference tray to correct for buoyancy effects (hot trays weigh less due to air buoyancy).
• Calculation and reporting:
  • Moisture content calculated on a wet basis from mass loss (includes formula and rounding rules).
  • Procedure allows correction when sample was pre-dried.
  • Tests performed in duplicate; drying time generally should not exceed 24 hours.

Applications and who uses it

ISO 18134-1:2022 is used by:

• Laboratory analysts and accredited testing labs for quality control and reference measurements.
• Biomass producers, pellet manufacturers and fuel suppliers for product specification and trading.
• Certification bodies and regulatory agencies for compliance testing and fuel classification.
• R&D and energy auditors calculating fuel moisture for combustion efficiency, calorific value adjustments and storage management.

Practical uses include contractual moisture verification, optimizing combustion performance, storage and handling decisions, and comparative method validation.

Related standards

• ISO 14780 - Sample preparation
• ISO 16559 - Solid biofuels vocabulary
• ISO 18135 - Sampling
• ISO 21945 - Simplified sampling for small-scale applications

Keywords: ISO 18134-1:2022, solid biofuels, moisture content, oven drying, reference method, wet basis, sample preparation, buoyancy correction, VOC.