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Initial NVFEL Evaporative Emission Test Results from Marine Fuel Tanks

Initial NVFEL Evaporative Emission Test Results from Marine Fuel Tanks

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Initial NVFEL Evaporative Emission Test Results from Marine Fuel Tanks

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  1. Initial NVFEL Evaporative Emission Test Results from Marine Fuel Tanks • Test Procedures • Baseline Emissions • Pressure Relief Valves • Limited Flow Orifices • Volume Compensating Bag • Insulation • Permeation • Future Testing • Examples of Certification Meeting Between Industry and EPAAugust 7, 2001

  2. 38 36 34 32 30 SHED Temperature [Celcius] 28 26 24 22 20 0 12 24 36 48 60 72 Test Time [hours] Test Procedures • 72-96 F (22-36 C) diurnal • highest of 3 days (1 day used here to save time when testing pressure strategies) • measured in SHED • certification fuel • soaking required to stabilize permeation 40% fill 9 RVP gasoline Sealed Housing for Emission Determination

  3. Test Tanks and Baseline Emissions Moeller, blow molded, portable tank, 6 gallon 2.3 g/gal/day* *adjusted from 50% to 40% fill Inca, rotationally molded, installed tank, 23 gallon 2.5 g/gal/day Wade-Reddy Model 2.3 g/gal/day Inca, rotationally molded, installed tank, 31 gallon have not tested yet Ezell, aluminum, installed tank, 17 gallon 2.2 g/gal/day

  4. Pressure Relief Evaporative Emission Test Data Aluminum Marine Fuel Tank 2.5 2 1.5 HC [grams/gallon/day] 1 0.5 0 0 0.5 1 1.5 2 2.5 Pressure Relief Setting [psi] Pressure Relief Valves • We modified an automotive cap with to allow us to vary the spring tension • Tests performed on aluminum fuel tank to remove the variable of permeation

  5. Limited Flow Orifices • Looked at three orifice sizes • orifice limits rate of vapor leaving tank • this increases the pressure in the tank • 25 micron • peak delta P of 3.1 psi (did not start test at zero psi, so will retest) • 0.24 g/gal/day (probably good--appears sonic flow maintained) • 75 micron • peak pressure of 1.6 psi • 1.2 g/gal/day

  6. Pressure, Temperature, and HC Traces Temperature Temperature Emissions Emissions Pressure (1.4 psi peak) Pressure (1.6 psi peak)

  7. Volume Compensating Bag • Purpose of bag is to expand and contract to minimize pressure build-up • We tested a 1.5 gallon bag in 6 gallon tank • Peak pressure 0.8 psi • 0.4 g/gal/day (likely permeation) • 3 day test • Tedlar bag We are looking into other bag materials

  8. Insulation • The purpose of the insulation is to minimize the change in temperature the fuel sees through the day • We insulated the flat plastic tank with 3 inches construction foam (R-15) and saw about a 50% reduction in emissions • We are looking into insulation that may be more appropriate for this application • Initial testing on a PWC suggests fuel temperature follows ambient temperature

  9. Permeation • EPA testing • new blow molded tank showed low permeation • new rotationally molded tank showed higher permeation • currently soaking 3 plastic tanks to stabilize permeation rates • looking into impermeable materials/treatments • Other data • 1992 data on high-density polyethylene automotive tank • 3.0 g/day on a 22 gallon tank (0.14 g/gal/day) • 1986 USCG data on 3 rotationally molded tanks at 104 F • 18 g/day on a 12 gallon tank (1.5 g/gal/day) • 25 g/day on an 18 gallon tank (1.4 g/gal/day) • 20 g/day on an 18 gallon tank (1.1 g/gal/day) • Suggests permeation may be significant contributor to evaporative emissions

  10. Future Testing • Collecting more data to better define a correlation between technology combinations and emissions for the purposes of design-based certification • Permeation testing (and materials investigation) • Investigate insulation further • Diurnal and LFO tests on the plastic tanks • Open to other technology options • bladder, floating vapor barrier, others?

  11. Example of Design-Based Certification • NOTE: we are still refining our design criteria and will continue to do so as we collect more data • EXAMPLE • Baseline = 2.2 g/gal/day aluminum tank • If targeting a 50% reduction • COULD USE: • R-15 insulation with LFO to prevent convection • 1.5 psi pressure relief valve • possibly R-10 insulation with 1.0 psi pressure relief valve • (with a plastic tank, may need to use non-permeable material or target lower diurnal emissions to offset permeation)

  12. Example of Credits Calculation for ABT • Consider averaging to a 50% reduction from 2.2 • product of ten 100 gallon tanks and five 50 gallon tanks • want to avoid new technology on 50 gallon tanks • Calculating Debits • 5 tanks X 60 gallons X (2.2-1.1 g/gal/day) = 330 • Need to make up with credits • 330 / (10 tanks X 100 gallons) = 0.33 g/gal/day • 1.1 - 0.33 = 0.77 g/gal/day • If certified 100 gallon tanks to 0.7 g/gal/day • 10 tanks X 100 gallons X (1.1-0.7 g/gal/day) = 400 • would be able to bank or trade 400 - 330 = 70 credits