Materials Compatibility

B20 or lower blends minimize most issues associated with materials compatibility. Experience over the last 10 years indicates B20 compatibility with all elastomers in diesel fuel systems, even those such as nitrile rubber, that are sensitive to higher blends. Customers should thus continue to check for and fix leaks.

Improper or lengthy storage of biodiesel or biodiesel blends can result in oxidation and the formation of corrosive organic acids and water that can adversely affect vulnerable materials. Although only limited research has been done on this issue, tests indicate that the degree of oxidation may be more important than the concentration of biodiesel. Unless used within a few months, biodiesel and biodiesel blends should be stabilized with antioxidants to reduce susceptibility to oxidation and degradation.

B20 may degrade faster than petroleum diesel if oxidizing metals such as iron, rust, copper, bronze, brass, or zinc are in fueling systems. If filters clog more frequently with B20 than with petroleum diesel, the fueling system should be checked for these materials and they should be replaced with biodiesel-compatible parts. Typically, these metals are found in lead solders, zinc linings, copper pipes, and brass and copper fittings. Stainless steel, carbon steel, and aluminum are good replacements. Data on the materials compatibility of biodiesel blends are summarized in Appendix C.