ISO 6669:1995

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

• ISO 1447 (moisture - routine)
• ISO 6673, ISO 11294 (loss on drying methods)
• ISO 11817 (Karl Fischer for roasted coffee)
• ISO 3509 (vocabulary)
• ISO 4072 (sampling of green coffee)

Keywords: ISO 6669:1995, bulk density, free‑flow bulk density, green coffee, roasted coffee, whole beans, coffee quality control, routine method.