BS EN 15751:2014

What is BS EN 15751- Acelerated oxidation method for determination of the oxidation stability of fuels about?

BS EN 15751 specifies a test method for the determination of the oxidation stability of fuels for diesel engines, by means of measuring the induction period of the fuel up to 48 h. The method is applicable to fatty acid methyl esters (FAME) intended for the use as pure biofuel or as a blending component for diesel fuels, and to blends of FAME with diesel fuel containing 2 % (V/V) of FAME at minimum.

Note 1: EN 14112 [1] describes a similar test method for oxidation stability determination of pure fatty acid methyl Esters.

Note 2: For induction periods higher than 48 h the precision is not covered by the precision statement of this method. The limit values of the relevant fuel standards are well within the scope of this test method.

Note 3: The presence of cetane improver can reduce the oxidation stability determined by this test method. Limited studies with EHN (2-ethyl hexyl nitrate) indicated, however, that the stability is reduced to an extent which is within the reproducibility of the test method.

Who is BS EN 15751- Acelerated oxidation method for determination of the oxidation stability of fuels for?

BS EN 15751 on acelerated oxidation method for determination of the oxidation stability of fuels is useful for:

• The petroleum industry
• Testing laboratories
• Diesel fuels engine manufacturers
• Quality control authorities
• Relevant compliance bodies

Why should you use BS EN 15751- Acelerated oxidation method for determination of the oxidation stability of fuels?

The oxidation stability of fuels is essential for knowing the suitability of fuel and to identify the impact on the diesel engine. BS EN 15751 provides you with guidance on carrying out accelerated oxidation method for determining the oxidation stability of fuels.

In the method described in BS EN 15751, the oxidation process is split in two phases.

• The first phase (the induction period) is characterised by slow reaction of oxygen during which peroxides are formed
• The second phase is characterised by rapid reaction in which peroxides are not only formed but these peroxides are then dissociated under the influence of the high temperature. During this reaction, products such as aldehydes, ketones and short chain carboxylic acids are formed

The method described in BS EN 15751 is a conductometric determination of volatile carboxylic acids (mainly formic acid and acetic acid) produced during oxidation.

BS EN 15751 is based on EN 14112 [1], which was specifically adapted for the determination of oxidation stability of fatty acid methyl esters (FAME). This method had been developed under CEN/TC 307 (Fats and oils). At the time of development the method was applicable for FAME fuel according to EN 14214 [2], but questions remained on the accuracy towards blends of FAME and diesel fuel.

The modifications to EN 14112 as given in BS EN 15751, allow application of this test method for oxidation stability for pure FAME and diesel/FAME blends at various levels.

The goal of BS EN 15751 is to have one single test method for FAME fuel, diesel/FAME blends and pure diesel fuels.

Although the modifications cover FAME fuel and diesel/FAME blends, CEN/TC 307 decided that it was better to retain EN 14112 for methyl esters and publish a separate standard for all automotive fuel and heating oil applications, as the use of 'diesel and diesel blends' falls out the scope of CEN/TC 307.

Note: The modifications required a new validation covering pure FAME, diesel/FAME blends and pure diesel fuels which resulted in the fact that the method is not suitable for pure petroleum-based diesel fuels.

What’s changed since the last update?

BS EN 15751:2014 supersedes EN 15751:2009. BS EN 15751:2014 includes some technical changes with respect to EN 15751:2009. These include:

• The limitation of the scope of the method to a maximum induction period of 48 h, reflecting the precision range of the method
• Indication of a potential alteration of the induction period in the presence of cetane enhancers
• Inclusion of the results of a short applicability check on non-petroleum based (such as Fischer-Tropsch Synthesis or hydrotreatment process originated) diesel type of fuels (see Introduction)
• Editorial changes in order to clarify the test procedure