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ISO 18123:2016 – Determination of Volatile Matter in Solid Biofuels
Technical requirements and compliance guidance for accurate volatile matter analysis according to ISO 18123
Introduction
ISO 18123:2016 (also adopted as CAN CSA ISO 18123-16) specifies a method for the determination of the volatile matter content in solid biofuels. This parameter is crucial for assessing fuel combustion behaviour, energy conversion efficiency, and overall fuel quality. The standard is part of the ISO 17225 series on solid biofuels and is widely referenced in trading, certification, and regulatory frameworks. This article provides a detailed technical overview of the standard’s scope, key requirements, implementation considerations, and compliance notes.
Scope and Application
ISO 18123:2016 applies to all solid biofuels derived from biomass, including but not limited to wood chips, pellets, briquettes, agricultural residues, and treated biomass materials. The method is intended for the determination of the mass loss of a test portion when heated in a crucible under standardized conditions, excluding the mass lost as moisture. The result is expressed as a percentage of the dry mass.
Note: The standard explicitly excludes fuels that undergo significant decomposition below the test temperature (e.g., fresh biomass with high extractive content). In such cases, pre-treatment or alternative procedures may be required.
Technical Requirements
Apparatus
| Component | Specification |
|---|---|
| Furnace (muffle furnace) | Electrically heated, capable of maintaining (900 ± 10) °C, with air inlet and exhaust |
| Crucibles | Platinum or porcelain, with tightly fitting lids, dimensions per ISO 18123 |
| Desiccator | Containing an efficient desiccant (e.g., silica gel) with a moisture indicator |
| Analytical balance | Readability of 0.1 mg or better |
| Drying oven | Capable of (105 ± 2) °C for moisture determination |
Test Procedure
- Prepare the test sample according to ISO 14780 (reduction and division of combined samples). The particle size should be less than 1 mm.
- Determine the moisture content of the sample (ISO 18134-1 or -2) to enable calculation on a dry basis.
- Weight a test portion of (1.0 ± 0.1) g into a pre-weighed crucible with lid.
- Place the covered crucible into the furnace preheated to (900 ± 10) °C for exactly 7 minutes.
- After heating, cool the crucible in a desiccator and reweigh.
- Calculate volatile matter content as the percentage loss of mass, corrected for moisture.
Calculation
The volatile matter content on a dry basis (Vd) is given by:
Vd = [(m1 – m2) / (m1 × (100 – M))] × 104
where m1 = initial mass, m2 = final mass, M = moisture content (%).
Precision
| Repeatability limit (r) | Reproducibility limit (R) |
|---|---|
| 0.5 % absolute | 1.0 % absolute |
Values from interlaboratory trials; actual precision may vary depending on fuel type and laboratory conditions.
Implementation tip: Ensure that the furnace temperature is uniform across the heating zone. Baffles or periodic calibration using reference materials can help maintain accuracy.
Implementation Highlights
- Sample preparation: Grind to < 1 mm; avoid overheating during milling which can volatilize compounds
- Moisture correction: Essential; always determine moisture on a separate portion at 105 °C
- Heating parameters: Strictly control temperature and time (7 min at 900 °C). Even a 10 °C deviation can affect results
- Safety: Use protective gloves and goggles; the furnace and crucibles are extremely hot
- Quality control: Include a reference material or duplicate analysis every 10 samples
Warning: Never place cold crucibles directly into the hot furnace; preheat them gently to avoid thermal shock and breakage.
Compliance Notes
Laboratories seeking accreditation for ISO 18123:2016 must demonstrate:
- Participation in proficiency testing schemes (e.g., BIPEA, PREIS)
- Validated in-house methods with documented precision and bias
- Proper training for all analysts
- Adherence to the quality control requirements of ISO 17025
Common pitfall: Using incorrect moisture determination (e.g., routine drying at 105 °C after volatile matter test) can invalidate the correction. Always use a separate portion for moisture.
Frequently Asked Questions
Q: What is the difference between ISO 18123 and ASTM E872?
A: Both methods determine volatile matter in biomass, but ISO 18123 uses a fixed 7-minute heating time at 900 °C, while ASTM E872 specifies 6 minutes at 950 °C. The results are not directly interchangeable; users should specify the standard applied.
A: Both methods determine volatile matter in biomass, but ISO 18123 uses a fixed 7-minute heating time at 900 °C, while ASTM E872 specifies 6 minutes at 950 °C. The results are not directly interchangeable; users should specify the standard applied.
Q: Can ISO 18123 be used for all types of solid biofuels?
A: Yes, for most solid biofuels, but caution is needed for high-extractive materials (e.g., resinous wood). The standard recommends verifying that no visible signs of incomplete carbonization remain after the test.
A: Yes, for most solid biofuels, but caution is needed for high-extractive materials (e.g., resinous wood). The standard recommends verifying that no visible signs of incomplete carbonization remain after the test.
Q: How should the volatile matter data be reported?
A: Report the mean value of duplicate determinations on a dry basis (wt%), rounded to 0.1%. Always state the basis (dry, as received, etc.) and the standard (ISO 18123:2016).
A: Report the mean value of duplicate determinations on a dry basis (wt%), rounded to 0.1%. Always state the basis (dry, as received, etc.) and the standard (ISO 18123:2016).
© 2026 – This technical article is provided for informational purposes and does not substitute the official standard document. Always refer to the latest version of ISO 18123 for official requirements.