ISO 17225-3:2021

Overview

ISO 17225-3:2021 - "Solid biofuels - Fuel specifications and classes - Part 3: Graded wood briquettes" defines fuel quality classes and technical specifications for graded wood briquettes made from virgin wood, wood-processing residues and chemically untreated used wood. It is the second edition (2021), updating raw-material coverage and some chemical property values. Thermally treated briquettes (e.g. torrefied) are explicitly excluded.

Keywords: ISO 17225-3:2021, graded wood briquettes, solid biofuels, fuel specifications, fuel quality classes.

Key topics and technical requirements

The standard specifies classification, sampling, analysis and product declaration requirements. Important technical topics include:

• Fuel quality classes - Classes A1, A2 and B tied to raw-material origin (forest/plantation wood, residues, untreated used wood; class B can include certain chemically treated by-products if safe).
• Physical properties - Mandatory declaration of briquette dimensions (diameter, length, width, height) and particle density (DE ≥ 1.0 g/cm³ for A1; ≥ 0.9 g/cm³ for A2/B).
• Moisture and ash - Moisture limits: M12 ≤ 12% (A1), M15 ≤ 15% (A2/B). Ash limits: A1 ≤ 1.0% (dry), A2 ≤ 3.0%, B ≤ 5.0%.
• Calorific value - Net calorific value (as received): Q ≥ 15.5 MJ/kg (A1) and Q ≥ 14.4 MJ/kg (A2/B).
• Chemical contaminant limits - Specified maximums for nitrogen, sulfur, chlorine and heavy metals, e.g. N ≤ 0.3% (A1), S ≤ 0.04% (A1/A2), Cl ≤ 0.02% (A1) and limits for As, Cd, Cr, Cu, Pb, Hg, Ni, Zn (mg/kg, dry) to control emissions and protect appliances.
• Additives - Additives allowed up to 2% mass; type and amount must be declared.
• Sampling & analysis - Refers to ISO sampling and test methods (ISO 18135, ISO 14780, ISO 18122, ISO 18125, ISO 16948/16968/16994, ISO 18847, etc.).

Applications

ISO 17225-3:2021 is used to:

• Standardize product declarations for trading and procurement of wood briquettes.
• Ensure appliance compatibility and lower emissions in residential, small commercial and public buildings.
• Support quality assurance at production lines and by testing laboratories.
• Facilitate regulatory reporting, permitting and communication between suppliers, buyers and equipment manufacturers.

Who uses this standard

• Briquette manufacturers and suppliers
• Testing and certification laboratories
• Heating appliance and boiler manufacturers
• Energy buyers, distributors and public authorities
• Quality managers and procurement teams in residential and commercial heating sectors

Related standards

• ISO 17225-1 (general requirements for solid biofuels)
• ISO test standards cited for sampling and analysis (ISO 18134, 18122, 18125, 16948, 16968, 16994, 18847)
• Relevant appliance standards (EN 13229, EN 12815, EN 12809, EN 13240, EN 15250, EN 15821)

Using ISO 17225-3:2021 helps producers and buyers ensure consistent, safe and marketable graded wood briquettes that meet defined performance and environmental criteria.