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Understanding ISO 17225-7-15: Specifications for Graded Non-Woody Briquettes
Comprehensive guide to the international standard for non-woody briquettes and its Canadian adoption CAN/CSA-ISO 17225-7-15
Scope and Purpose
ISO 17225‑7‑15 (adopted in Canada as CAN/CSA‑ISO 17225‑7‑15) specifies the fuel classes and quality requirements for graded non‑woody briquettes derived from solid biofuels. These briquettes are manufactured from herbaceous biomass (e.g., straw, hay, grass), fruit biomass (e.g., olive stones, nut shells), or mixtures thereof. The standard covers briquettes intended for residential, commercial, and industrial combustion applications, providing a clear classification system that enables transparent trade and consistent end‑use performance.
The standard applies only to non‑woody briquettes that have been intentionally densified by compression. It does not cover woody briquettes (covered by ISO 17225‑3), pellets (ISO 17225‑2, ISO 17225‑6), or raw biomass that has not been processed into a uniform briquette form. ISO 17225‑7‑15 helps producers, regulators, and consumers to define fuel quality, test methods, and labeling requirements that support efficient, safe, and environmentally responsible use of biogenic solid fuels.
Technical Requirements
Classification
The standard defines three quality classes for non‑woody briquettes, based on end‑use sector and acceptable thresholds for key fuel properties:
- Class A – Residential use with burners designed for high‑quality, low‑ash fuels
- Class B – Commercial or institutional use with moderate tolerance for ash and minor elements
- Class I – Industrial applications with higher allowable limits for ash, nitrogen, sulfur, and chlorine
Key Fuel Properties
Producers must declare the following parameters, each determined by the applicable ISO test methods (e.g., ISO 18122 for ash, ISO 18125 for calorific value):
- Moisture content (w−% as received)
- Ash content (w−% dry basis)
- Net calorific value (MJ/kg as received)
- Bulk density (kg/m³)
- Mechanical durability (w−% after tumbling)
- Diameter and length (mm)
- Nitrogen, sulfur, and chlorine content (w−% dry basis)
The following table summarizes typical limit values for each class as prescribed by the standard:
| Property | Class A | Class B | Class I |
|---|---|---|---|
| Moisture, w‑% (ar) | ≤ 12 | ≤ 15 | ≤ 18 |
| Ash, w‑% (d) | ≤ 6 | ≤ 10 | ≤ 15 |
| Sulfur, w‑% (d) | ≤ 0.10 | ≤ 0.20 | ≤ 0.30 |
| Nitrogen, w‑% (d) | ≤ 0.70 | ≤ 1.50 | ≤ 2.00 |
| Chlorine, w‑% (d) | ≤ 0.03 | ≤ 0.08 | ≤ 0.15 |
| Bulk density, kg/m³ | ≥ 600 | ≥ 550 | ≥ 500 |
Note: Values are illustrative; exact limits are specified in the official normative tables of ISO 17225‑7‑15. “ar” = as received, “d” = dry basis.
Additional Specifications
The standard also sets limits for mechanical durability (min. 97.5% for Class A) and requires that briquettes be free from visible mold, fungal growth, and unacceptable amounts of mineral contaminants. Particle size distribution and fines content are controlled to prevent handling and combustion problems.
Implementation Tip: When selecting or specifying non‑woody briquettes, always verify that the supplier’s certificate of analysis references ISO 17225‑7‑15 and clearly states the intended class. This ensures compatibility with your combustion equipment and emissions control strategy.
Implementation Highlights
Adoption of ISO 17225‑7‑15 facilitates the following practical benefits:
- Uniform quality classification – Producers label briquettes with a consistent class, enabling cross‑border trade without additional testing.
- Equipment optimization – Combustion systems designed for a specific class operate more efficiently, with lower maintenance and reduced emissions.
- Quality assurance – The standard defines sampling and test methods (e.g., ISO 18134 for moisture, ISO 18122 for ash), providing a clear framework for routine quality control.
- Market transparency – End‑users can compare fuels on an equivalent basis, promoting competition and innovation in the biofuel sector.
Benefits: Clear classification helps reduce air pollution and ash‑related problems in small‑scale combustors. Many Canadian jurisdictions reference CAN/CSA‑ISO 17225‑7‑15 as a recognized fuel standard for financial incentive programs.
Compliance Notes
Compliance with ISO 17225‑7‑15 is generally voluntary in Canada but is often required by regional incentive programs, such as those administered by the BC Energy Step Code or provincial biomass support schemes. Key compliance considerations include:
- Testing frequency – At least one sample is required for each batch of 500 t of briquettes; many producers opt for more frequent testing to demonstrate consistency.
- Documentation – A certificate of conformity or declaration of performance must accompany each delivery, stating the class, declared values, and test methods used.
- Third‑party certification – While not mandated by the standard itself, independent certification (e.g., to ENplus or the Canadian Bioenergy Association program) can enhance market acceptance.
- Non‑compliance risks – Use of briquettes that do not meet the claimed class can lead to combustion inefficiency, excessive slagging, regulatory penalties, or voiding of equipment warranties.
Compliance Warning: Always retain test reports for at least two years. If a batch fails to meet its declared class, it cannot be marketed as graded under ISO 17225‑7‑15; it must be re‑classified or used in less demanding applications.
Risk: Utilizing briquettes with high ash or chlorine content in uncertified residential stoves can cause corrosion, exceed local emission limits, and create a fire hazard from excessive clinker formation.
Frequently Asked Questions
Q: What is the difference between non‑woody briquettes and woody briquettes in ISO standards?
A: Woody briquettes (ISO 17225‑3) are made from whole trees, logging residues, or wood processing by‑products. Non‑woody briquettes (ISO 17225‑7) originate from herbaceous crops, crop residues, fruit biomass, or aquatic biomass. The two standard parts have different class limits for ash, nitrogen, sulfur, and chlorine to account for the inherently higher mineral content of many non‑woody feedstocks.
A: Woody briquettes (ISO 17225‑3) are made from whole trees, logging residues, or wood processing by‑products. Non‑woody briquettes (ISO 17225‑7) originate from herbaceous crops, crop residues, fruit biomass, or aquatic biomass. The two standard parts have different class limits for ash, nitrogen, sulfur, and chlorine to account for the inherently higher mineral content of many non‑woody feedstocks.
Q: How does CAN/CSA‑ISO 17225‑7‑15 relate to the international ISO 17225‑7:2014?
A: CAN/CSA‑ISO 17225‑7‑15 is the identical adoption of ISO 17225‑7:2014 by the CSA Group. It contains no technical deviations; only administrative and linguistic adjustments to conform to Canadian standards publishing practices. Therefore, a briquette certified to ISO 17225‑7:2014 automatically meets the requirements of the Canadian adoption.
A: CAN/CSA‑ISO 17225‑7‑15 is the identical adoption of ISO 17225‑7:2014 by the CSA Group. It contains no technical deviations; only administrative and linguistic adjustments to conform to Canadian standards publishing practices. Therefore, a briquette certified to ISO 17225‑7:2014 automatically meets the requirements of the Canadian adoption.
Q: Can I use non‑woody briquettes in any stove or boiler?
A: Only if the equipment is designed or certified for non‑woody fuels. Many residential appliances are tested exclusively with woody pellets or briquettes. Using a non‑woody briquette with high ash content may impair combustion, damage heat exchangers, and lead to excess particulate emissions. Always consult the manufacturer’s specifications.
A: Only if the equipment is designed or certified for non‑woody fuels. Many residential appliances are tested exclusively with woody pellets or briquettes. Using a non‑woody briquette with high ash content may impair combustion, damage heat exchangers, and lead to excess particulate emissions. Always consult the manufacturer’s specifications.
Q: What is the significance of the “fines” limit in the standard?
A: Fines are small particles produced by breakage during transport or handling. High fines fraction can block feeding systems, increase pressure drop, and cause uneven combustion. ISO 17225‑7‑15 restricts fines (particles <3.15 mm) to ≤ 5% for all classes, ensuring good handling behavior.
A: Fines are small particles produced by breakage during transport or handling. High fines fraction can block feeding systems, increase pressure drop, and cause uneven combustion. ISO 17225‑7‑15 restricts fines (particles <3.15 mm) to ≤ 5% for all classes, ensuring good handling behavior.
© 2026 – This article provides a summary of the technical content of ISO 17225‑7‑15 / CAN/CSA‑ISO 17225‑7‑15. For complete normative requirements, refer to the official standard published by the CSA Group or ISO.