B5 and Lower Blends

The specification for conventional diesel fuel, ASTM D975, allows for up to 5 vol% biodiesel to be blended into compliant diesel fuels. The biodiesel used in the blend must meet D6751. Blends up to B5 must meet all the numeric requirements for diesel fuel properties specified in D975; none were changed or relaxed to accommodate biodiesel. ASTM Method D7371, Standard Test Method for Determination of Biodiesel (Fatty Acid Methyl Esters) Content in Diesel Fuel Oil Using Mid Infrared Spectroscopy (FTIR-ATR-PLS Method), may be used to determine the biodiesel blend percentage. There is no requirement that D975-compliant fuels list the percent of biodiesel in the blend. Users may not know if the fuel they are using or purchasing is B0, B2, or B5 unless they measure the biodiesel content using ASTM D7371 or an alternate method.