Technical Paper
Impact and Control of Canister Bleed Emissions
2001-03-05
2001-01-0733
Current EPA and CARB regulations allow a maximum of 2.0 g/test for Hot Soak + Diurnal evaporative emissions. The State of California has adopted LEV II regulations that will decrease the evaporative emissions standard to 0.5 g/test starting in the 2004 model year. These regulations also include a Zero Emission Vehicle or ZEV program. The ZEV program allows car manufacturers to substitute vehicles that meet the SULEV tail pipe emission standards and have zero fuel evaporative emissions for electric vehicles. The increased stringency of these regulations has necessitated significant decreases in hydrocarbon emissions from evaporative emission canisters. For example, canister vent emissions may be at levels of 100-300 mg/test for a vehicle that meets the current regulations. However, canister emission targets should be 50 mg/test and less for LEV II and 10 mg/test and less for zero evaporative emission vehicles.