High Efficiency Diesel Fuel Filtration - A Case Study

Fuel injector wear and the resulting alterations of the spray pattern, injection timing, leakage rate and fuel quantity delivered are known to cause excessive smoke in the engine exhaust. A field test was conducted at a major transit property, utilizing 3μm rated (β₃ ≥ 200) secondary fuel filters to ascertain if these high efficiency filters effectively remove and retain fine particulate contaminants that would otherwise wear critical surfaces in an injector. The test was conducted on six buses, two of these buses had engines fitted with new rebuilt injectors. During the test, the median particle count of fuel sampled downstream of the high efficiency filters was over 30 times lower than that of the fuel supply (for 2μm and larger size particles). Nearly all the smoke opacity results were lower than the target value of 20%. The new rebuilt injectors were removed after 19 weeks of service and evaluated by the manufacturer for wear. Microscopic examination of critical wear areas of the plunger and bushing assembly and the valve seat on all four injectors examined indicated no discernable wear. Five of the six test filters were in service a year after their installation.