ISO 17308:2015

Overview

ISO 17308:2015 - Petroleum products and other liquids - Ethanol - Determination of electrical conductivity specifies a laboratory test method to measure the electrical conductivity of ethanol fuel and ethanol blends (including E85). The standard covers measurements in the range 0.5 μS·cm−1 to 4 μS·cm−1 at a reference temperature of 25 °C, determining conductivity from the measured electrical conductance between electrodes.

Key topics and requirements

• Scope and range: Measurement range 0.5–4 μS·cm−1 at 25.0 ± 0.1 °C. Results reported to 0.01 μS·cm−1 resolution.
• Measurement principle: Conductivity determined from alternating-current conductance between a conductivity cell’s electrodes to avoid faradaic effects; electrode surfaces can be platinised to increase capacitance and reduce polarization.
• Apparatus:
  • Conductivity meter compatible with a 0.1 cm cell constant (±0.02 cm) and frequency 50–500 Hz.
  • Conductivity cell inert to ethanol (platinised or non-platinised) and integrated temperature sensing or compensator.
  • Thermostatic bath or vessel and magnetic stirrer for temperature homogeneity.
• Calibration and reagents:
  • Use KCl calibration solutions (example composition: 70% de‑ionized water / 30% 1‑propanol) or certified reference materials (~5 μS·cm−1 or up to 25 μS·cm−1).
  • De‑ionized water with conductivity ≤ 0.5 μS·cm−1 and anhydrous ethanol for cleaning.
  • Cell-constant check: acceptable meter reading between 0.08 cm and 0.12 cm when calibrated.
• Sampling and sample handling:
  • Follow ISO 3170 or ISO 3171 for sampling; use clean glass bottles and rinse containers with the product before sampling.
  • Clean sample vessels and cells thoroughly to avoid contamination (special care after saline exposure).
• Temperature correction and expression of results:
  • Reference temperature 25 °C; standard temperature correction coefficient 2.2%/°C if meter does not auto-correct.
  • Report conductivity at 25 °C in μS·cm−1 (or S·m−1).
• Performance:
  • Repeatability r = 0.08 μS·cm−1; reproducibility R = 0.22 μS·cm−1.

Applications and users

ISO 17308:2015 is used for fuel quality control and contamination assessment where electrical conductivity of ethanol fuels is critical. Typical users:

• Analytical laboratories testing ethanol and ethanol blends (including E85)
• Fuel producers, blenders and distributors monitoring storage and transport cleanliness
• Regulatory bodies and standards organizations setting fuel quality criteria
• Equipment manufacturers (conductivity meters, measurement cells) validating instrument performance

Measuring conductivity helps detect ionic contamination (water, salts, additives) that can accelerate corrosion and affect engine/fuel-system performance.

Related standards

• ISO 3170 - Petroleum liquids - Manual sampling
• ISO 3171 - Petroleum liquids - Automatic pipeline sampling
• Annex A of ISO 17308 provides additional guidance on conductance vs conductivity and measurement considerations.

Keywords: ISO 17308:2015, electrical conductivity, ethanol fuel, E85, conductivity measurement, conductance, fuel quality, conductivity cell.