Overview
ISO 17829:2015 specifies standardized methods for the determination of length and diameter of pellets used as solid biofuels. The standard defines sampling preparation, measurement procedures, calculation rules and reporting requirements to classify pellet diameter, calculate average length and quantify the proportion of oversize pellets. It supports compliance with fuel specifications referenced in ISO 17225 series and helps avoid handling and combustion problems caused by out-of-spec pellets.
Key topics and technical requirements
- Scope: measurement of pellet diameter and length, including the proportion of pellets exceeding specified maximum lengths.
- Sample preparation: test samples obtained per EN 14778 and reduced per EN 14780; two test portions are required - one of 10 pellets (diameter classification) and a larger portion (mass or 40–50 pellets) for length assessment. Test portion sizes vary by pellet size class (examples: ≤6 mm → ~30–40 g; >8 mm → ~40–50 g; >12 mm → ~70–120 g; >25 mm → min 50 pellets).
- Apparatus: measuring caliper with at least 0.1 mm resolution; balance readable to 0.01 g; sieve with round holes 3.15 mm (ISO 3310-2) for sieving per ISO 18846.
- Measurement principle: length measured along the pellet axis; diameter measured perpendicular to axis. Record individual measurements for statistical analysis.
- Procedures:
- Diameter class determined from 10-pellet test portion; average and standard deviation reported to 0.1 mm.
- Individual pellet lengths measured for the larger test portion; calculate mean and standard deviation to 0.1 mm.
- Oversize determination: sieve and sort pellets, weigh fractions to determine weight-percent (w-%) of pellets longer than the maximum length specified in applicable ISO 17225 parts.
- Calculations and reporting: mean, standard deviation, w-% oversize, number of pellets above maximum length and any unusual observations. The test report must reference ISO 17829 and identify laboratory and sample.
Applications and users
ISO 17829:2015 is used for quality control, certification and acceptance testing of solid biofuel pellets. Typical users:
- Pellet manufacturers and quality labs (incoming/outgoing inspection)
- Independent testing laboratories and certification bodies
- Fuel suppliers and wholesalers (product specification verification)
- Boiler and burner manufacturers, and facility operators concerned with fuel handling (screw conveyors, silo outlets, feeders)
- Procurement and regulatory agencies ensuring conformity to ISO 17225 standards
Practical benefits include consistent pellet sizing data, reduced handling/feeding issues, and clearer compliance with graded wood and non-wood pellet specifications.
Related standards
- ISO 17225-1, -2, -6, -8 (fuel specifications and pellet dimensions)
- ISO 16559 (terminology)
- EN 14778, EN 14780 (sampling and sample preparation)
- ISO 18846 (fines content / sieving)
- ISO 3310-2 (test sieves)
Keywords: ISO 17829, ISO 17829:2015, solid biofuels, pellet length, pellet diameter, pellet measurement, oversize pellets, pellet size classification, caliper measurement, sieve 3.15 mm.
