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The function of the engine air cleaning filter is to remove the particulate matter in the intake air to protect the engine and its components from wear and contamination. For a specific filter, the efficiency is a function of the size of the particles being collected and the air flow velocity through the filter. Traditional tests of engine air cleaners are based on the use of specific test dusts, such as the AC Coarse and AC Fine, to determine the mass collection efficiency. However, they do not provide information on the size dependent performance of the filters, and the variation in filter performance under different particle challenge conditions. The use of a fractional efficiency test method will help to provide this missing information. The purpose of this paper is to describe a fractional efficiency test system that has been designed to evaluate the fractional cleaning efficiency of engine air cleaning filters in the size range between 0.3 and 10 mm particle diameter.

The performance of the air cleaning filter is important to the long-term performance and reliability of the engine and its components. In this study, the performances of cellulosic and foam filter media for engine air cleaning application are experimentally investigated. Phenolic and non-phenolic cellulose filters were studied. Both flat-sheet and pleated cellulose filters were included. The foams filters were reticulated polyurethane foam media from 20 to 110 pores-per-inch. We measured the initial air flow resistance, the collection efficiency as a function of particle size, and the behavior of dust loading. We also studied the effect of oil treatment on filter performance. The results show that the efficiencies and pressure drops of the cellulose filters increase rapidly with dust loading. Oil treated cellulose filter was found to exhibit slower increases in pressure drop and collection efficiency, resulting in higher dust holding capacity.

Fuel Vapor Storage Systems (FVSS) on automobiles are susceptible to particle contamination. This is especially true for FVSS components mounted under the automobiles (undercarriage, chassis frame, etc.) and required to meet stringent EPA standards. Particle contamination significantly increases system restriction and reduces the effectiveness of FVSS. This paper describes a dust separator/filter developed to protect the FVSS. Accelerated field durability evaluations and measurement techniques were developed to identify clean locations, ingested contamination levels and ingested contaminant size distributions. Based on field evaluations, test methods were developed in the lab to evaluate effectiveness of several devices to control and reduce contamination. The dust separator design developed was a combination of baffle separators in series with an open cell foam filter. The dust separator was designed to meet and exceed several vehicle system design requirements.