Reduction of Hydrocarbon Permeation through SORE Oil Seals and Fuel System Components

Environmental actions by the California Air Resources Board (CARB) may have a significant effect on emission requirements in the Small Off-Road Engine (SORE) segment. Meeting these new proposed standards will require material and design changes to engine seals, fuel hoses, and fuel tanks. New membrane filter technology is also being developed to manage diurnal emissions from fuel systems. This paper discusses what these options are in each of the critical application areas. Relative permeation rates of the various materials were determined by either a simple gravimetric cup method or a gas chromatographic technique that permits identification of the permeating species. Data from experiments of this type were shown to correlate well with results obtained on actual parts in the Sealed Housing Evaporative Determination Test (SHED).