Overview
EN ISO 6246:2017 (endorsed by CEN) defines the jet evaporation method for measuring the gum content of fuels. It specifies procedures to determine the existent gum in aviation turbine fuels and the gum content of motor gasoline and other volatile distillates, including products containing ethanol (up to 85 % by volume), ether-type oxygenates, and deposit-control additives. The standard aligns with modern fuel blends and replaces earlier editions.
Key Topics
- Scope and warning
- Tests cover aviation fuels and non‑aviation volatile distillates; E85 (automotive ethanol) gum analysis has no precision data provided (see clause 14.1).
- Contains a safety caution: not intended for some gasoline components with high fractions of low‑boiling unsaturated compounds (risk of explosion during evaporation).
- Principle
- Evaporate a measured fuel portion under controlled temperature and a flow of air or steam; weigh the resulting evaporation residue (gum).
- For non‑aviation fuels, an additional heptane extraction step is described to determine the heptane‑insoluble portion (removes non‑volatile oils/additives).
- Terminology
- Existent gum: evaporation residue of aviation fuels without further treatment.
- Unwashed gum and solvent‑washed gum: terms used for non‑aviation fuels (before and after heptane washing).
- Reagents and supplies
- Typical reagents: heptane, toluene, acetone, and a 1:1 toluene/acetone gum solvent.
- Air supply: filtered, gauge pressure ≤ 35 kPa; steam supply: oil‑free, pressure ≥ 35 kPa.
- Method components
- Apparatus assembly (air‑jet and steam‑jet setups), calibration, sampling, test procedure, calculation and expression of results, and precision information (repeatability/reproducibility).
Applications
- Who uses it
- Fuel testing laboratories, refinery and distribution quality control, aviation fuel handlers, fuel additive manufacturers, regulatory bodies, and organizations responsible for fuel specification compliance.
- Practical value
- Detects contamination, higher‑boiling oils or particulate carryover in aviation fuel handling and storage.
- Helps assess oxidation products and potential induction‑system deposit risks in motor gasoline.
- Supports quality control for modern blended fuels containing ethanol and oxygenates.
Related Standards
Relevant normative references cited in EN ISO 6246:2017 include:
Keywords: EN ISO 6246:2017, ISO 6246:2017, gum content, jet evaporation method, aviation fuels, motor gasoline, E85, heptane‑insoluble, existent gum, solvent‑washed gum, fuel quality testing.