Test Method Revised to Support Ethanol Spec

Members of ASTM International recently revised a key test method (D1613) that has been used to measure the acidity of fuel ethanol and denatured fuel ethanol, including ethanol used for car gasoline blends.
By including a new “nitrogen purge” as part of the test method, a laboratory can help ensure that carbon dioxide is removed. According to member Shon Van Hulzen, the presence of carbon dioxide is known to produce incorrectly high acidity values which can affect the product’s ability to comply with the specification for denatured fuel ethanol used in automotive spark-ignition engines (D4806).
“Historically, the test method did not specifically require a purge step,” says Van Hulzen. “But if denatured fuel ethanol samples are not purged, it can often lead to erroneously high acidity results due to entrained carbon dioxide.”
Notably, this purge is already required in the test method for acidity in ethanol and ethanol blends by titration (D7795).
D1613 is formally known as the “standard test method for acidity in volatile solvents and chemical intermediaries used in paint, varnish, lacquer, and related products.” It was revised by the committee on paint and related coatings, materials, and applications (D01).