ASTM D7462 - Oxidation Stability of Biodiesel (B100) and Blends of Biodiesel with Middle Distillate Petroleum Fuel (Accelerated Method)
Signiﬁcance and Use
5.1 This test method provides a measurement of the oxidation stability of biodiesel and biodiesel blends.
5.2 The test method may not provide a prediction of the quantity of insolubles that will form in ﬁeld storage over any given period of time. The amount of insolubles formed in such ﬁeld storage is subject to the speciﬁc storage conditions, which are too variable for this test method to predict accurately.
5.3 This test method yields results more rapidly than Test Method D4625, the 43°C bottle test. However, as a result of the signiﬁcantly elevated temperature and the pure oxygen atmosphere, the nature and amount of insolubles may deviate to a greater extent than Test Method D4625 from those formed in ﬁeld storage.
1.1 This test method covers a measurement of the oxidation stability of biodiesel (B100) blendstock as speciﬁed in Speciﬁcation D6751 and blends of biodiesel with middle distillate petroleum fuels, including B6 to B20 blends as speciﬁed in Speciﬁcation D7467 under speciﬁed oxidizing conditions at 95°C. Speciﬁcally, the oxidation stability is assessed by the formation and measurement of insoluble degradation materials.
NOTE 1—Biodiesel B100, composed of alkyl esters, can have good solubility for some products of oxidative degradation. Thus some B100 samples could undergo signiﬁcant degradation, but show little or no sediment formation. By contrast, many petroleum diesel fuels have relatively poor solubility for products of oxidative degradation, so Bxx blends, such as B20, could show higher sediment levels. Refer to Appendix X1 for a suggested paraffinic dilution procedure to evaluate oxidative degradation of B100 for degradation materials that are soluble in B100, but insoluble in isooctane.
NOTE 2—No. 1 and No. 2 grades in Speciﬁcations D396 or D975 currently allow up to 5% biodiesel meeting Speciﬁcation D6751. This method is preferred for testing these fuels that may contain biodiesel blendstock rather than Test Method D2274 due to the incompatibility of biodiesel blendstock with the membrane ﬁlters speciﬁed in Test Method D2274.
Extracted, with permission, from ASTM D7462-11 - Oxidation Stability of Biodiesel (B100) and Blends of Biodiesel with Middle Distillate Petroleum Fuel (Accelerated Method), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be purchased from ASTM International, astm.org