Overview
ISO 6246:2017 - "Petroleum products - Gum content of fuels - Jet evaporation method" specifies a laboratory procedure to determine the existent gum content of aviation turbine fuels and the gum content of motor gasoline and other volatile distillates using the jet‑evaporation technique. The scope explicitly includes fuels containing ethanol (up to 85% v/v), ether‑type oxygenates and deposit‑control additives. For non‑aviation fuels the standard also describes determination of the heptane‑insoluble portion of the evaporation residue.
Key topics and technical requirements
- Principle: Evaporate a measured test portion under a controlled flow of air or steam; weigh the evaporation residue and, for non‑aviation fuels, perform a heptane wash to obtain solvent‑washed gum.
- Apparatus & reagents:
- Balance capable of 0.1 mg resolution.
- 100 ml tall beakers (individually marked) and cooling vessel.
- Evaporation bath with air‑jet or steam‑jet outlets fitted with 500–600 µm screens.
- Flow indicator to ensure ~1 000 ml/s ±150 ml/s per outlet; steam superheater delivering steam at ~232 °C ±3 °C.
- Temperature monitoring (thermometers or equivalent) and sintered‑glass filter funnels; heptane, toluene, acetone and gum solvent (toluene/acetone 1:1).
- Operating conditions:
- Air‑jet wells nominally at ~155 °C (±5 °C allowed between wells); steam‑jet well temperature control and superheater settings specified.
- Cleaning and calibration procedures are included; sample handling and sampling reference ISO 3170 / ISO 3171.
- Results & precision:
- Results expressed as existent (aviation fuels), unwashed and solvent‑washed (non‑aviation fuels).
- The standard contains precision data (repeatability/reproducibility) based on historical ASTM/EI studies; note that for automotive E85 no precision data are available in clause 14.1.
- Safety: Explicit warnings about flammable/combustible vapours and thermal explosion risk; labs must follow national health & safety rules.
Applications
- Quality control of aviation turbine fuels to detect contamination (high gum indicating oils, particulates or poor handling).
- Measurement of oxidation/deposit precursors in motor gasoline and blended gasoline (including ethanol blends up to E85).
- Product testing for compliance, refinery QA, downstream fuel handling audits, and additive evaluation.
Who uses this standard
- Petroleum testing laboratories, fuel producers, airlines and aviation fuel handlers, automotive fuel formulators, regulatory agencies, and standards bodies concerned with fuel deposit control and fuel quality.
Related standards
Keywords: ISO 6246:2017, gum content, jet evaporation method, aviation fuels, motor gasoline, E85, heptane‑insoluble, air‑jet, steam‑jet, fuel quality.
