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The Beta ratio and filtration ratio are two common rating systems used to designate the abrasive filtration efficiency of fuel filters. Previous research developed a series of wear curves to predict the effects of abrasive particles of varying sizes on fuel injector performance. Based on this data, a formula was generated to predict injector wear based on the number of 5-, 10-, and 15-μm particles in the effluent. This value is called the wear index. (1,2)1 Various fuel filters with the same manufacturer rating were evaluated on a test engine to determine the wear index for each of these fuel filters. The results demonstrate the differences between these “similar” fuel filters and how the wear index provides additional information as compared to Beta and filtration ratios.

The critical particle size for a high-pressure injection system was determined. Various double-cut test dusts ranging from 0 to 5 μm to 10 to 20 μm were evaluated to determine which test dust caused the high-pressure system to fail. With the exception of the 0- to 5-μm test dust, all test dust ranges caused failure in the high-pressure injection system. Analysis of these evaluations revealed that the critical particle size, in initiating significant abrasive wear, is 6 to 7 μm. Wear curve formulas were generated for each evaluation. A formula was derived that allows the user to determine if the fuel filter effluent will cause harmful damage to the fuel system based on the number of 5-, 10-, and 15-μm particles per milliliter present. A methodology was developed to evaluate fuel filter performance as related to engine operating conditions. The abrasive methodology can evaluate online filter efficiency and associated wear in a high-pressure injection system.

A cooperative research and development program was organized to determine the critical particle size of abrasive debris that will cause significant wear in rotary injection fuel pumps. Various double-cut test dusts ranging from 0-5 to 10-20 μm were evaluated to determine which caused the pumps to fail. With the exception of the 0-5-μm test dust, all other test dust ranges evaluated caused failure in the rotary injection pumps. After preliminary testing, it was agreed that the 4-8-μm test dust would be used for further testing. Analysis revealed that the critical particle size causing significant wear is 6-7 μm. This is a smaller abrasive particle size than reported in previously published literature. A rotary injection pump evaluation methodology was developed. During actual operation, the fuel injection process creates a shock wave that propagates back up the fuel line to the fuel filter.

Alternative fuels are being evaluated in automotive applications in both commercial and government fleets in an effort to reduce emissions and United States dependence on diesel fuel. Vehicles and equipment have been operated using 100 percent biodiesel and various blends of biodiesel and diesel fuel in a variety of applications, including farming equipment and transit buses. This government study investigates the compatibility of four base fuels and six blends with elastomer and metallic components commonly found in fuel systems. The physical properties of the elastomers were measured according to American Society of Testing and Materials (ASTM) D 471, “Standard Test Method for Rubber Property-Effect of Liquids,” and ASTM D 412, “Standard Test Methods for Rubber Properties in Tension.” These evaluations were performed at 51.7°C for 0, 22, 70, and 694 hours. Tensile strength, hardness, swell, and elongation were determined for all specimens.