Overview
ISO 18301:2014 specifies the oscillating U‑tube method for determining the conventional mass per volume (litre weight in air) of animal and vegetable fats and oils that are single‑phase liquids at the test temperature. The method covers oils and fats with litre weights in the range 0,800 kg/l to 1,000 kg/l. It is an automatic laboratory technique using a digital density meter and is not intended for calibrating online density meters.
Keywords: ISO 18301:2014, oscillating U‑tube method, litre weight in air, conventional mass per volume, fats and oils density.
Key Topics and Requirements
- Principle: A small sample (~1 ml) in a temperature‑controlled cell alters the oscillation frequency of a U‑tube; litre weight is calculated from measured frequencies and previously determined cell constants.
- Apparatus:
- Digital density (oscillating U‑tube) meter with resolution ±0,0001 kg/l or better.
- Constant‑temperature bath (if external) able to maintain ±0,05 °C where required.
- Calibrated temperature sensor (accuracy at least 0,1 °C).
- Heated injection device recommended for samples solid at room temperature.
- Calibration & verification:
- Calibrate with one or two traceable calibration media close to sample litre weight.
- Verify calibration within seven days prior to use.
- Cell constants are calculated by the instrument from calibration media readings.
- Sample preparation:
- Follow ISO 661 for test‑sample preparation.
- Heat samples to at least 10 °C above melting point and avoid entrained air.
- Clean and dry cell using suitable flushing solvent (acetone preferred) and dry air.
- Measurements & calculations:
- Record steady readings (stable to within 0,1 g/l) and cell temperature to 0,1 °C.
- Convert litre weight to a different reference temperature using correction factor 0,00068 per °C (for differences ≤ 3 °C).
- Precision: Repeatability and reproducibility data are provided (see Annex A of the standard).
Applications and Users
- Practical for quality control laboratories, commercial testing labs, terminals and shipping operations where converting volume to mass (e.g., tank dip to mass) is required.
- Used by food and edible‑oil industry, refiners, traders, and laboratories measuring density of vegetable oils, animal fats and related products.
- Valuable where accurate, traceable density/litre weight data are needed for trade, inventory and shipping documentation.
Related Standards
- ISO 661 - Preparation of test sample (referenced)
- ISO 3696 - Water quality (grade 2) for calibration media
- ISO 6883 - Manual pyknometer method (alternative manual technique)
Using ISO 18301:2014 ensures consistent, traceable density (litre weight) measurements of fats and oils with clear requirements for calibration, temperature control and sample handling.
Open preview (PDF)Animal and vegetable fats and oils — Determination of conventional mass per volume (litre weight in air) — Oscillating U-tube method