Overview
ISO 3889:2006 (IDF 219:2006) specifies the design and dimensional requirements for Mojonnier-type fat extraction flasks used in gravimetric determination of fat in milk and milk products. The standard ensures flasks reliably allow a supernatant solvent layer to be decanted almost completely from an underlying aqueous layer - a critical feature for accurate milk fat determination using Mojonnier extraction and related gravimetric methods.
Key topics and technical requirements
- Material
- Flasks shall be made from clear borosilicate glass (glass tubing per ISO 4803).
- Wall thickness: 1.4 mm ± 0.2 mm, and free from visible defects.
- Construction
- Join in the glass stem must be as free from striations as possible and positioned perpendicular to the stem axis, preferably nearer the lower bulb, to avoid obscuring the solvent/aqueous interface.
- Form and closure
- Three permissible forms (A, B, C) are illustrated; neck must be circular in cross-section and fitted with a pouring rim or spout to enable tight stopper closure.
- Note: spherical lower-bulb forms (B and C) are particularly suitable for direct heating.
- Dimensional requirements (highlights from Table 1)
- Lower and upper bulb external diameter: 35.0 mm ± 1.8 mm
- Lower bulb + stem capacity: 24 ml ± 2 ml
- Stem external diameter: 16 mm ± 1 mm
- Neck external diameter: 18.0 mm ± 0.5 mm
- Angles between bulbs: 112° ± 3° (A/B) or 128° ± 3° (C)
- Overall length: 185 mm ± 15 mm
- Guidance dimensions (Table 2): total capacity difference ~100 ml ± 10 ml, neck length 17 mm ± 2 mm
- Practical manufacturing notes
- Tolerances accommodate common centrifuge buckets; however, some buckets cannot accept flasks exceeding 36.5 mm external diameter.
Applications and users
- Primary use: gravimetric fat extraction in milk, cream, cheese, dried milk and other dairy matrices.
- Suitable for use with ISO reference methods including ISO 1211, ISO 1735, ISO 1736, ISO 1737, ISO 1854, ISO 2450, and ISO 5543.
- Typical users:
- Dairy quality control and testing laboratories
- Analytical chemists and lab technicians performing Mojonnier extraction
- Laboratory glassware manufacturers and suppliers
- Standards professionals and test method developers
Related standards
Keywords: ISO 3889:2006, Mojonnier-type fat extraction flasks, milk fat determination, gravimetric methods, borosilicate glass, dairy testing, laboratory glassware.
