(5) The gasoline-fueled and methanol-fueled light-duty vehicles and light-duty trucks covered by an application for certification will be divided into groupings which are expected to have similar evaporative and/or refueling emission characteristics (as applicable) throughout their useful life. Each group of vehicles with similar evaporative and/or refueling emission characteristics shall be defined as a separate evaporative/refueling emission family.
(6) For gasoline-fueled or methanol-fueled light-duty vehicles and light-duty trucks to be classed in the same evaporative/refueling emission family, vehicles must be similar with respect to the items listed in paragraphs (a)(6) (i) through (xii) of this section.
(i) Type of vapor storage device (e.g., canister, air cleaner, crankcase).
(ii) Basic canister design.
(A) Working capacity—grams adsorption within a 10g. range.
(B) System configuration—number of canisters and method of connection (i.e., series, parallel).
(C) Canister geometry, construction and materials.
(iii) Fuel system.
(iv) Type of refueling emission control system—non-integrated or integrated with the evaporative control system. Further, if the system is non-integrated, whether or not any other evaporative emissions, e.g. diurnal or hot soak emissions, are captured in the same storage device as the refueling emissions.
(v) Fillpipe seal mechanism—mechanical, liquid trap, other.
(vi) Fill limiter system.
(vii) Vapor control system or method of controlling vapor flow through the vapor line to the canister.
(viii) Vapor/liquid separator usage.
(ix) Purge system (valve, purge strategy and calibrations).
(xii) Onboard diagnostic hardware and calibrations.
(7) Where vehicles are of a type which cannot be divided into evaporative/refueling emission families based on the criteria listed above (such as non-canister control system approaches), the Administrator will establish families for those vehicles based upon the features most related to their evaporative and/or refueling emission characteristics.
(vii)(A) Vehicles of each evaporative/refueling emission family will be divided into evaporative/refueling emission control systems.
(B) The Administrator will select the vehicle expected to exhibit the highest evaporative and/or refueling emissions, from within each evaporative/refueling family to be certified, from among the vehicles represented by the exhaust emission-data selections for the engine family, unless evaporative and/or refueling testing has already been completed on the vehicle expected to exhibit the highest evaporative and/or refueling emissions for the evaporative/refueling family as part of another engine family's testing.
(C) If the vehicles selected in accordance with paragraph (b)(1)(vii)(B) of this section do not represent each evaporative/refueling emission control system then the Administrator will select the highest expected evaporative/refueling emission vehicle from within the unrepresented evaporative/refueling system.
(viii) For high-altitude evaporative and/or refueling emission compliance for each evaporative/refueling emission family, the manufacturer shall follow one of the following procedures:
(A) The manufacturer will select for testing under high-altitude conditions the one nonexempt vehicle previously selected under paragraph (b)(1)(vii)(B) or (b)(1)(vii)(C) of this section which is expected to have the highest level of evaporative and/or refueling emissions when operated at high altitude; or
[59 FR 16290, Apr. 6, 1994, as amended at 75 FR 22979, Apr. 30, 2010]
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