Vehicle Onboard Control of Refueling Emissions — System Demonstration on a 1985 Vehicle

Two technologies for controlling vehicle refueling emissions have been under consideration by the U. S. Environmental Protection Agency. They are vehicle onboard systems and Stage II service station vapor recovery. A 1978 program showed that onboard systems are very effective in controlling refueling emissions with no significant effect on exhaust emissions. The work reported herein shows that vehicle onboard technology can be applied equally well to a car meeting more stringent 1985 exhaust and evaporative emission standards with the latest engine and emission control technology. This work also shows that a vehicle onboard refueling control system can provide substantially improved control of evaporative emissions. Refueling emissions were controlled with 98+% efficiency in tests with 9-to 11.5-psi RVP fuel at 88°F, using a procedure proposed by EPA for possible use in certification testing of vehicle onboard systems. Evaporative emissions were controlled to the extent that the present 2.0 g/test standard prescribed for 9-psi RVP certification fuel was met with an 11.5-psi RVP fuel, typical of commercial gasoline. The refueling control canister can be purged faster than necessary to restore its capacity in the current EPA draft procedure and without any significant effect on exhaust emissions or driveability. The system is simple in design and construction and should be readily adaptable to current automotive production methods and materials.