Overview
ISO 3013:1997 specifies a laboratory method for determining the freezing point of aviation fuels - the temperature at which solid hydrocarbon crystals disappear on warming. This second edition (1997) covers aviation turbine fuels and aviation gasolines and defines apparatus, reagents, test procedure, thermometer requirements (Annex A), precision limits and reporting. The method is widely used for fuel certification, quality control and cold-weather performance assessment.
Key Topics and Requirements
- Scope: Determination of the temperature below which solid hydrocarbon crystals are present (freezing point) and the temperature at which crystals first appear (crystallization point).
- Sample: Transfer 25 ml ± 1 ml into a clean, dry jacketed sample tube; position thermometer bulb 10–15 mm above tube center.
- Apparatus:
- Jacketed sample tube (double-walled, unsilvered) in an unsilvered vacuum flask.
- Stirrer: brass or stainless rod, 1.6 mm diameter, with three-loop spiral; stirring rate 1–1.5 cycles/s.
- Moisture‑proof collar (type A or B) to prevent moisture ingress.
- Thermometer conforming to Annex A (range -80 °C to +20 °C, 0.5 °C graduations, specified stem/bulb dimensions and calibration).
- Coolants: preferred liquid propan-2-ol combined with solid carbon dioxide (dry ice) or liquid nitrogen where required. Other acceptable liquids: ethanol, acetone, methanol. Liquid nitrogen permitted only for aviation gasolines or when freezing point