Overview
ISO 6669:1995 specifies a routine method for determining the free‑flow bulk density of whole green or roasted coffee beans. The procedure measures the mass of beans that freely flow from a calibrated hopper into a known‑volume receptacle and expresses bulk density in grams per litre (g/L) (or kg/m³). This method is intended for whole beans only and is not suitable for ground roasted coffee.
Key topics and technical requirements
- Scope: Free‑flow bulk density of whole green or roasted coffee beans; excludes ground coffee.
- Apparatus:
- Analytical balance with 0.1 g precision.
- Hopper (conical trémie) of ~1.6 L volume with stainless steel valve.
- Measuring receptacle ≈ 1 000 mL capacity; volume known to ±1 mL.
- Spatula or straight‑edged leveling tool.
- Critical dimensions / settings:
- Distance from hopper valve outlet to top of receptacle: 76.2 mm ± 1.5 mm.
- Hopper fill: to about 2.5 mm below hopper top.
- Sampling & sample size:
- From a laboratory sample, take at least three test samples of 300 g each.
- Perform two determinations for bulk density and use the third sample to determine moisture content.
- Moisture determination:
- For green coffee: use ISO 1447 or ISO 6673 (loss on drying at specified temperatures).
- For roasted coffee: use ISO 11817 or ISO 11294 (Karl Fischer or loss on drying methods).
- Calculation:
- Bulk density (g/L) = (m2 − m1) / V
- m1 = mass of empty receptacle (g)
- m2 = mass of receptacle filled by free‑flowing beans (g)
- V = receptacle volume (L)
- Repeatability requirement:
- Absolute difference between two independent results (same operator, same lab) must not exceed 1% of their arithmetic mean.
Applications and users
ISO 6669:1995 is used for:
- Packaging design and fill‑volume calculations
- Storage and transport planning (bulk volume estimates)
- Commercial trading and specification verification
- Quality control in green coffee reception and post‑roast inventory management
- Process control for roasting and handling equipment (hoppers, conveyors)
Typical users: coffee producers, exporters, green bean merchants, roasters, packing plants, QA/QC laboratories, commodity traders and logistics planners.
Related standards
Keywords: ISO 6669:1995, bulk density, free‑flow bulk density, green coffee, roasted coffee, whole beans, coffee quality control, routine method.
Open preview (PDF)Green and roasted coffee — Determination of free-flow bulk density of whole beans (Routine method)