Overview
ISO 18708:2025 specifies a standardized laboratory method to determine the bulk density of solid recovered fuels (SRF) using a standard measuring container. The method applies to SRF materials whose nominal top particle size is less than one third of the selected container diameter. Results are reported as mass per standard volume and accompanied by the determined moisture content to enable comparable, actionable data for sampling, transport, storage and energy calculations.
Key topics and technical requirements
- Scope & principle
- Bulk density = mass of the test portion / volume of the filled container under specified conditions.
- Densification is achieved by controlled shock exposure before weighing.
- Standard measuring containers
- Large: ~50 L (inner Ø 360 mm, height 491 mm); volume tolerance ±2%
- Medium: ~20 L (inner Ø 265 mm, height 362 mm); volume tolerance ±2%
- Small: ~5 L (inner Ø 167 mm, height 228 mm); volume tolerance ±2%
- Containers must be cylindrical, shock-resistant, smooth-surfaced, waterproof and maintain shape.
- Instruments & equipment
- Scales: nearest 10 g for large/medium containers; nearest 1 g for small container.
- Scantling (for levelling) and a wooden OSB board (for shock exposure).
- Sample handling
- Sampling per ISO 21645 and sample preparation per ISO 21646.
- Test portion volume must exceed container volume by ≥30%.
- Container volume is determined by weighing filled with water and converting to litres.
- Particle size and drop-height rules
- Method applies when nominal top size
