Fuel vapour composition and flammability properties of E85

Fuel vapour composition and flammability properties of E85 A series of experiments have been conducted to study the flammability characteristics and determine the flammable temperature range of E85 fuel vapours. E85 is a mixture of ethanol and petrol the composition varies depending on time of the year. According to the Swedish standard, SS 155480:2006, the ethanol content may not be below 70 %/75 % (winter/summer) and may not exceed 86%. E85 of summer and winter qualities were conditioned in sealed vessels at various temperatures and the composition and concentration of the fuel vapours were determined. Fuel vapours from conditioned vessels were also used for ignition tests in an explosion chamber (the bomb). The tests shows that the fuel vapours mainly consist of petrol fractions despite the high content of ethanol in the liquid phase. The bomb tests indicate a flammable range of the fuel vapours from about -18 °C up to about +2°C to +5°C for E85 of summer quality. Some tests with E85 of winter quality and petrol were conducted as well. These tests indicated a flammable range up to -8 °C to -9 °C for the winter E85 and up to about -20 °C for petrol. The lower limit of the flammable range was not investigated for these fuels. The consequences of ignition of fuel vapours inside some fuel tanks for cars have also been studied. Electrical sparks were generated inside the tank or at the filling opening. In addition, a spill fire below the tank was used as an ignition scenario. When the ignition occurred inside the tanks, the overpressure caused a rupture and generated a short duration flame outside the tank. Tests have also been conducted to study the fuel vapour concentration and composition around the filling pipe during filling of the tank. The measurements indicate that vapours in the flammable range might be present around the filling opening, especially if the vapour recovery system at the fuel pump is not activated. One test with a fuel tank equipped with an Onboard Refuelling Vapour Recovery (ORVR) system, indicated that the fuel vapour emission was very low, probably reducing the risk for ignition of fuel vapours significant during filling.