Fuel Filter Plugging by Insoluble Sediment in Diesel Fuels

Abstract

Diesel fuels contaminated with insoluble sediment and water have caused problems for light-duty diesel engines by plugging fuel filters. The sediment consists of either aggregated gum particles resulting from fuel oxidation or biological slime produced by micro-organisms that grow at the water/fuel interface. Laboratory experiments were conducted to understand the mechanism of filter plugging by these sediments. Gum particles tend to be hard and spherical in shape, while biological growth tends to consist of long, stringy, fibrous material. Biological slime plugged both the 10 μm-engine filter and the 130-μm tank sock filter; gum particles, which individually were less than 3 μm in diameter, plugged the 10-μm engine filter by forming aggregates of several hundred particles; these aggregates readily passed through the 130-μm tank sock filter. However, plugging with these aggregates was not very severe because a porous cake formed on the surface of the filter paper that allowed some fuel to flow. Filter plugging was very severe when gummy fuel was contaminated with water because the particles flocculated and plugged both of the filters. Prevention of water contamination and treatment of diesel fuel with additives to prevent gum and biological growth formation are necessary to avoid filter plugging problems.