ISO 17831-1:2025

Overview

ISO 17831-1:2025 - Solid biofuels: Determination of mechanical durability of pellets (Part 1: Pellets) defines a standardized laboratory method to measure the mechanical durability of compressed biomass pellets. Mechanical durability quantifies a pellet’s resistance to shocks and abrasion during handling and transport by tumbling a test portion, sieving out generated fines, and reporting the proportion of material retained.

Key topics and requirements

• Scope: Method for pellets (typically ≤ 25 mm diameter); part of the ISO 17831 series for solid biofuels.
• Test principle: Tumbling in a rotating, dust-tight pellet tester with internal baffle to induce collisions; subsequent sieving to remove fines < 3.15 mm; mechanical durability reported as percentage retained.
• Apparatus:
  • Pellet tester box (stainless steel) with specified internal dimensions and baffle; smooth internal surfaces and rounded fastenings.
  • Rotation speed: (50 ± 2) r/min; test duration: 500 rotations.
  • Circular sieve with 3.15 mm round holes (ISO 3310-2), collecting pan, sieve template (ISO 5370), and balance (readability 0.1 g).
• Sample preparation:
  • Minimum laboratory sample: 2 kg (obtained per ISO 18135 or ISO 21945).
  • Remove existing fines by sieving (ISO 5370) and use two test portions of (500 ± 10) g each.
  • Measure moisture content on a sub-sample (ISO 18134-1 or ISO 18134-2).
• Calculation and reporting:
  • Mechanical durability D = (mass after tumbling / mass before tumbling) × 100.
  • Results for two test portions are averaged; replicate results rounded to 0.1%.
  • Test report must include laboratory ID, product identification, reference to ISO 17831-1:2025, results (mean and moisture content), and any unusual features.
• Performance characteristics:
  • Repeatability and reproducibility limits specified (e.g., if D ≥ 97.5%: repeatability 0.3 pp, reproducibility 0.6 pp; if D < 97.5%: repeatability 2 pp, reproducibility 3 pp).

Applications and users

• Quality control and production for pellet manufacturers to monitor durability and reduce fines.
• Accredited testing laboratories and certification bodies performing compliance testing.
• Supply chain stakeholders (logistics, storage, end-users) evaluating pellet robustness for handling and transport.
• R&D groups optimizing pellet formulations, binders, and production parameters.
• Policy-makers and procurement teams using standardized durability metrics in specifications.

Related standards

• ISO 5370 - Determination of fines content in pellets
• ISO 14780 - Sample preparation
• ISO 18134-1 / ISO 18134-2 - Moisture content methods
• ISO 18135 / ISO 21945 - Sampling methods
• ISO 3310-2 - Test sieves
• ISO 17225-1, ISO 16559 - Fuel specs and vocabulary

Keywords: ISO 17831-1:2025, mechanical durability, pellets, solid biofuels, pellet tester, fines, tumbling test, sieving, sample preparation, repeatability, reproducibility.