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Permeation Data Critique - 1

This article critiques the data on tank permeation and diurnal emissions reduction methods, such as sulfonation, fluorination, and SELAR. It also discusses the challenges with pressurized systems and the application of carbon canisters.

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Permeation Data Critique - 1

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  1. Permeation Data Critique - 1 • Originally, CARB wanted tank permeation reduced by using sulfonation, fluorination, and possibly SELAR - since the thinking was that equipment gas tanks were similar to gas cans. • Since then • sulfonation has not made the cut – per CARB data • fluorination may only work in some cases (see OPEI data for non-effectiveness in roto-molded tanks, as well as for barrier effectiveness variability, and effects of degradation). Many technical issues remain. • SELAR does not work with injection molded tanks The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  2. Permeation Data Critique - 2 • although there are many “potential” novel materials, there are no tanks from many of these at the present - hard to evaluate • CARB’s (and Honda’s) best data (around 11 data points collected around March 2003) show that: • if the molding process is “optimized” (not defined at this time) • and a qualitative level of “SL-5+” fluorination is used (extent of barrier parameters not objectively specified) • and not all of the durability requirements that CARB itself has specified are imposed (e.g., no 3000 pressure cycles, etc.) • the best results can range from between 0.4 to over 1 g/m2/day, subject to considerable variability The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  3. Permeation Data Critique - 3 • CARB’s own data shows considerable increase in permeation emissions (several-fold) after fluorination: • Could be due to durability aspects • in summary the 2 g/m2/d (at 40 C) rests on weak data The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  4. Diurnal Data Critique - 1 • To minimize diurnal emissions CARB proposes to: • pressurize tanks to 4 psig or more • Based on 1 set of CARB tests (one tank) and some recent data from EPA that are not directly comparable • Some manufacturers simply do not feel comfortable using pressurized systems on their products • The minimum cost relief valve to control pressure may be as large as $30.00 or so and this only “controls” set pressure to +/- 25% implying that tanks may have to be designed for pressures as large as 5 psig or more - further exacerbating safety and design risks The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  5. Diurnal Data Critique - 2 • use carbon canisters - generally in active mode with canister purge to engine when latter is running • Based on two tests by CARB (working with Delphi) on two engines • The data show widely variable “carburetor” emissions since only emissions remaining in each case (metal tanks, low-perm hose, 95%+ efficient canister etc.) can only be due to carburetor. • Numerous issues associated with active systems not as yet evaluated including significant fire hazard issues when next to catalyst exhausts • possibly require redesigning carburetors. CARB should explicitly consider this possibility in their staff report The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  6. Carbon Canister Application • Can not be applied directly to most current tanks with out redesign because the vent location currently is in the cap. This is much more than just adding a vent line to the tank. Liquid vapor separators will be required to prevent liquid fuel from reaching the canister. • Vent location must take into account machine attitude ( +- 20 degrees ANSI) during use and fuel agitation during rough ground use. No liquid fuel can enter the canister to be effective. The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

  7. Carbon Canister Application • OEM’s know little about carbon canisters and their application to our products. • Vibration • Small OEM’s do not have the testing capability to approve canisters • Break thru venting fire safety issues • Little cost information on systems for our sized units. • Dirty environment issues ( Dust/Debris) • Effect of Power washers The Outdoor Power Equipment Institute 341 South Patrick Street • Alexandria, VA 22314 • 703-549-7600 • 703-549-7604 FAX • www.opei.org

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