ISO 3013:1997

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 < -65 °C.
• Procedure:
  • Cool sample in the coolant while stirring; observe and record crystallization point when crystals first appear.
  • Remove tube, allow slow warming while stirring; record freezing point when crystals completely disappear.
  • Apply thermometer correction and report the corrected freezing point to the nearest 0.5 °C.
• Precision:
  • Repeatability (r) = 0.8 °C (same operator/apparatus)
  • Reproducibility (R) = 2.3 °C (different laboratories)
• Safety: warnings for extremely low temperatures, handling dry ice and liquid nitrogen, and general laboratory precautions.

Applications and Users

ISO 3013:1997 is used for:

• Quality control in refinery and fuel production laboratories
• Certification and acceptance testing by aviation fuel suppliers
• Operational planning for cold-weather fuel handling and storage
• Regulatory compliance testing and laboratory accreditation Typical users include fuel testing labs, refineries, airline fuel quality teams, military fuel analysts and national standard bodies.

Related Standards

• ISO 3170:1988 - Petroleum liquids - Manual sampling
• ISO 3171:1988 - Petroleum liquids - Automatic pipeline sampling
• ISO 4259 - Used for precision/statistical evaluation referenced in the standard

Keywords: ISO 3013:1997, freezing point determination, aviation fuels, crystallization point, fuel quality control, low-temperature fuel testing.