ONORM EN 15751:2025

Automotive fuels - Fatty acid methyl ester (FAME) fuel and blends with diesel fuel - Determination of oxidation stability by accelerated oxidation method at 110 °C

This document specifies a test method for the determination of the oxidation stability of fuels for diesel engines at 110 °C by measuring the induction time of the fuel up to 48 h. This method is applicable to fatty acid methyl esters (FAME) intended for use as pure biofuels or as a blending component for diesel fuels, and to blends of FAME with diesel fuel containing at least 2% (v/v) FAME. The precision of the test method has been determined for conventional diesel fuel. This test method is applicable to paraffinic diesel fuels as specified in EN 15940; however, a separate precision statement for paraffinic diesel fuel is not available. NOTE 1 EN 14112 [1] describes a similar test method for the determination of the oxidation stability of pure fatty acid methyl esters (see the introduction to this document). In addition, EN 16568 [4] describes a similar test method for determining the oxidation stability of diesel engine fuels at 120 °C by measuring the induction time of the fuel up to 20 h. EN 16568 is applicable for blends of FAME with diesel fuel containing at least 2% (v/v) FAME. Other alternative test methods for determining the oxidation stability of distillate fuels are described in CEN/TR 17225 [5]. NOTE 2 For induction times above 48 h, the precision is not covered by the precision statement of this method. The limits of the relevant fuel standards are within the scope of this method. NOTE 3 The presence of ignition improvers may reduce the oxidation stability determined using this method. However, limited studies with EHN (2 ethylhexyl nitrate) indicated that the stability is reduced to an extent that is within the comparability of this test method. NOTE 4 For the purposes of this document, the term ‘% (V/V)’ is used to express the volume fraction of a substance (f).