BS EN 14112-2016 pdf free download.Fat and oil derivatives — Fatty Acid Methyl Esters (FAME) — Determination of oxidation stability (accelerated oxidation test)
This European Standard specifies a method for the determination of the oxidation stability of fatty acid methyl esters (FAME) at 110 °C, by means of measuring the induction period up to 48 h.
NOTE 1 EN 15751 [1] describes a similar test method for oxidation stability determination of pure fatty acid methyl esters and of blends of FAME with petroleum-based diesel containing 2 % (V/V) of FAME at minimum.
NOTE 2 The precision statement of this test method was determined in a Round Robin exercise with induction periods up to 8,5 h, thus covering the limit value in EN 14214. Results from precision studies on EN 15751 indicate that the precision statement is valid for induction periods up to 48 h but not for higher values.
NOTE 3 Limited studies on EN 15751 with EHN (2-ethyl hexyl nitrate) on FAME blends indicated that the stability is reduced to an extent which is within the reproducibility of the test method. It is likely that the oxidation stability of pure FAMEs is also reduced in the presence of EHN when EN 14112 is used for testing.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 3170, Petroleum liquids – Manual sampling (ISO 3170) EN ISO 3171, Petroleum liquids – Automatic pipeline sampling (ISO 3171)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 induction period time which passes between the moment when the measurement is started and the moment when the formation of oxidation products begins to increase rapidly
3.2 oxidation stability induction period determined according to the procedure specified in this European Standard, expressed in hours 4 Principle A stream of purified (dried) air is passed through the sample which has been heated to the target temperature which is 110 °C in the usual application of the method. Volatile compounds are formed during the oxidation process. They are, passed together with the air into a flask containing demineralized or distilled water, equipped with a conductivity electrode.
The electrode is connected to a measuring and recording device. It indicates the end of the induction period by rapid increase of the conductivity due to the dissociation of volatile carboxylic acids produced during the oxidation process and absorbed in the water. For more details on the background of the method see Annex A.
5 Reagents and materials
Use only reagents of analytical grade and distilled or demineralized water.
5.1 Ternary solvent mixture, consisting of methanol/toluene/acetone 1:1:1 (by volume).
5.2 Alkaline laboratory glass cleaning solution.
5.3 2-Propanol.
6 Apparatus
Usual laboratory equipment and glassware, together with the following:
6.1 Device for the determination of oxidation stability, comprising the following parts (see Figures 1 and 2) 1) .
6.1.1 Air filter, comprising a tube fitted with filter paper at the ends and filled with a molecular sieve (6.6),connected to the suction end of a pump.
6.1.2 Gas membrane pump, with an adjustable flow rate of (10 ± 1,0) l/h.
6.1.3 Reaction vessels of borosilicate glass, provided with a sealing cap.
The sealing cap shall be fitted with a gas inlet and outlet tube.
6.1.4 Closed measurement cells, of approximately 150 ml capacity, with an air inlet tube extending to the bottom inside of the vessel. The cell shall have ventilation holes at the top.
6.1.5 Electrodes, for measuring conductivity within a range of 0 μS/cm to 300 μS/cm aligned with the dimensions of the measurement cell (6.1.4).
6.1.6 Measuring and recording apparatus, comprising:
a) an amplifier; and
b) a recorder registering the signal of each of the electrodes (6.1.5).
6.1.7 Thyristor and contact thermometer graduated in 0,1 °C or Pt 100 element to measure the block temperature, with attachments for relay connection and an adjustable heating element; temperature scale 0 °C to 150 °C.BS EN 14112 pdf download.