Range: 20-720
Unit: s
Objects: fatty acid methyl ester (FAME)
Some substances that are soluble or appear to be soluble in biodiesel (B100) at room temperature will, upon cooling to temperatures above the cloud point or standing at room temperature for extended periods, come out of solution. This phenomenon has been observed in both B100 and BXX blends. These substances can cause filter plugging. This method provides an accelerated means of assessing the presence of these substances in B100 and their propensity to plug filters. B100 biodiesel fuels that give short filtration times are expected to give satisfactory operation of BXX blends at least down to the cloud point of the biodiesel blends.
The test method can be used in specifications as a means of controlling levels of minor filter plugging components in biodiesel and biodiesel blends.
Summary of Test Method: In this test method, 300 mL of biodiesel (B100) is stored at 4,5 ± 0,5 0C (40 ± 1 0F) for 16 h, allowed to warm to 25 ± 1 0C (77 ± 2 0F), and vacuum filtered through a single 0,7 µm glass fiber filter at controlled vacuum levels of 70-85 kPa (21-25 in. of Hg). The filtration time is reported in seconds.
If the filtration of the 300 mL failed to be completed after 720 s, the result is reported as “B100 CSFT time greater than 720 s by ASTM D 7501” and is reported the volume which was filtered in 720 s in mL.
Requirements for CSFT according to ASTM D 6751 (“Standard Specification for Biodiesel Fuel Blend Stock (B100) for Middle Distillate Fuels”) are:
- max. 200 s - for B100 intended for blending into diesel fuel that is expected to give satisfactory vehicle performance at fuel temperatures at below – 12 0C
- max. 360 s – for biodiesel (B100)