Abstract |
The program involved the evaluation of 24 samples of charcoal from in-use evaporative canisters. The Environmental Protection Agency (EPA) provided the canisters from programs conducted by the EPA, Tennessee Valley Authority (TVA), and Southwest Research Institute (SwRI) on both alcohol blend-fueled and unleaded gasoline-fueled vehicles. Ten canisters from alcohol blend-fueled vehicles, eight from gasoline-fueled vehicles, and six from vehicles with unknown fuel histories were tested. A system was developed to remove and collect the effluent from samples of canister charcoal at room temperature (cold purge) and under heated conditions (hot purge). Charcoal samples of about 50 g were first cold purged with dry nitrogen at a flowrate of approximately 1.5 cfm. Butane working capacity was then measured, and the charcoal was subsequently hot purged at approximately 355-375 F (180-190 C). The effluent was sampled during selected cold and hot purge cycles and analyzed for water content, methanol, ethanol, tertiary butyl alcohol (TBA), total hydrocarbons (THC), and selected detailed hydrocarbons. |