ISO 17308:2015

Petroleum products and other liquids - Ethanol - Determination of electrical conductivity

ISO 17308:2015 specifies a test method for the determination of the electrical conductivity in ethanol fuel and mixtures (including E85) in the range of 0,5 μS·cm−1 to 4 μS·cm−1 at a temperature of 25 °C. The electrical conductivity is determined from the measured electrical conductance.

Produits pétroliers et autres liquides — Éthanol — Détermination de la conductivité électrique

General Information

• Status: Published
• Publication Date: 14-Jan-2015
• ICS: 75.160.20 - Liquid fuels
• ICS: 75.160.40 - Biofuels
• Technical Committee: ISO/TC 28/SC 7 - Liquid Biofuels
• Drafting Committee: ISO/TC 28/SC 7 - Liquid Biofuels
• Current Stage: 9093 - International Standard confirmed
• Start Date: 09-Oct-2023
• Completion Date: 13-Dec-2025

Relations

• Consolidated By: ISO 3104:2020 - Petroleum products - Transparent and opaque liquids - Determination of kinematic viscosity and calculation of dynamic viscosity
• Effective Date: 06-Jun-2022

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 17308
First edition
2015-01-15
Petroleum products and other
liquids — Ethanol — Determination of
electrical conductivity
Produits pétroliers et autres liquides — Éthanol — Détermination de
la conductivité électrique
Reference number
©
ISO 2015
© ISO 2015
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ii © ISO 2015 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Reagents . 1
5 Apparatus . 2
6 Sampling . 2
7 Apparatus calibration . 2
7.1 Cleaning of the sample vessel. 2
7.2 Cleaning of the measuring cell . 3
7.3 Checking the cell constant . 3
7.3.1 Principle . 3
7.3.2 Procedure . 3
8 Measurement procedure . 3
8.1 Using thermostatic bath or thermostatic vessel . 3
8.2 Using thermo compensation . 4
9 Expression of results . 4
10 Repeatability, r . 4
11 Reproducibility, R . 4
Annex A (informative) Guidance on conductance and conductivity . 5
Foreword
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The committee responsible for this document is ISO/TC 28, Petroleum products and lubricants,
Subcommittee SC 7, Liquid biofuels.
iv © ISO 2015 – All rights reserved

Introduction
Conductivity is related to the electrical current which is achieved by the ions displacement into solution
in an electrical field.
The importance of measuring conductivity is due to its role in corrosion processes which can harm
metallic components and therefore cause bad engine functioning at long term.
Ethanol can be contaminated with ion solutions in many ways, such as water contamination, chemical
treatment in industrial processes, addition of chemical additives, incorrect transportation and storage,
generally related to the cleanliness of tanks.
The ascertainment of the conductivity is usually carried out through the measurement of the electrical
conductance between two platinum electrodes, immersed in an electrolytic solution and connected
to a source of alternating electromotive force of a typical frequency. The resulting current is directly
proportional to the number of ions present in the solution, mobility and ionic valence, and temperature.
In the measuring of the conductance, it is essential to use an alternating current in order to eliminate
the undesirable effects of faradaic currents. In the case of an alternating resultant current, an inversion
of the polarization occurs every half cycle and, consequently, the inversion of the flow of the migration
of the ions, leading to a non-faradaic process, which comprises the formation of a double electrical layer
in the electrode-solution interface, called double electrical layer, with the potential decreasing linearly
in the first part and exponentially in the second part.
In an alternating fashion, the surfaces of the electrodes act as capacitors; the capacitive current increases
with the frequency and the size of the electrodes. The control of these variables is in order, so that the
alternating current flows preferentially in the form of non-faradaic processes. With an alternating current,
there is a reduction of the polarization effect and, as a consequence, an absence of faradaic currents.
In this sense, platinization, that is, covering the surface of the electrodes with a layer of platinum black,
increases its surface area significantly and, consequently, its capacitance which causes a reduction in the
faradaic current. Further, as a result of the increase in capacitance, there is a reduction in the capacitive
reactance, favouring the flow of current in the cell.
For both a metallic or electrolytic conductors, the Ohm Law (E = I·R) sets forth that the intensity of the
current (I) which passes through an electrical conductor is inversely proportional to the resistance
(R), where E represents the difference in potential and the inverse of the resistance is the conductance
(G = 1/R).Further information is provided in Annex A.
INTERNATIONAL STANDARD ISO 17308:2015(E)
Petroleum products and other liquids — Ethanol —
Determination of electrical conductivity
WARNING — The use of this International Standard can involve hazardous materials. This
International Standard does not purport to address all the safety problems associated with its
use. It is the responsibility of the user of this International Standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to use.
1 Scope
This International Standard specifies a test method for the determination of the electrical conductivity
−1 −1
in ethanol fuel and mixtures (including E85) in the range of 0,5 μS·cm to 4 μS·cm at a temperature of
25 °C. The electrical conductivity is determined from the measured electrical conductance.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its
...