Ethanol Fuel Corrosion Potential

Clear Determination of pHe According to ASTM D6423 and EN 15490

Engine corrosion is accelerated by excessive acidity in alcohol-based fuels. Total Acid Number, otherwise known as TAN, accounts for all titratable acids no matter their strength and therefore is unsuitable for prediction of the corrosion potential. On the other hand, pHe measures the sample to determine the strength of the acids present. For this reason, of the two, pHe is the better choice of the two for manufacturers to be able to:

  • Maintain the quality of their product
  • Monitor the corrosion potential
  • Maximize profits

A guide to measuring: ASTM D6423 and EN 15490

In ethanol and ethanol fuel blends, measurement of pHe is standardized in line with ASTM D6423 and EN 15490.

Metrohm Application Note AN-T-173

Assessing of the pHe value of denatured ethanol fuel in accordance with ASTM D6423

Metrohm Application Note AN-T-183

Ethanol as blending component for petrol – Value of pHe given according to EN 15490

EtOH Trode – is the Perfect Sensor for Achieving Precise, Consistent pHe Measurements Advised by the ASTM Standard

For correct pHe measurements, sensor design is crucial. A high leak-rate sleeve junction reference electrode is recommended by the ASTM standard, as well as a large membrane glass measuring electrode, given that these perform best in the measurement of alcohol fuels. ASTM D6432 recommends just two sensors as suitable for pHe measurements in ethanol and ethanol fuel blends, of which the Metrohm EtOH Trode is one.

Advantages of the EtOH Trode

  • It has full flexibility: The dual junction system permits the use of aqueous c(KCl) = 3 mol/L (ASTM D6423) or c(LiCl) = 1 mol/L in ethanol (EN 15490) as bridge electrolyte
  • It has increased accuracy: The fixed ground-joint diaphragm minimizes the potential drift due to a constant electrolyte leak rate
  • It boasts more stable readings: thanks to its low-resistance membrane glass with large surface area

This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.

For more information on this source, please visit Metrohm AG.


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