(iii) The trap is sealed and weighed after cooling and the weight, to the nearest 0.1 gram, is inscribed on the canister body. Within 12 hours of the scheduled test, the weight of the trap is checked and if it has changed by more than 0.5 gm., it is redried to constant weight. This redrying operation is performed by passing dry nitrogen, heated to 275° F., through the trap, via the inlet tube, at a rate of 1 liter per minute until checks made at 30-minute intervals do not vary by more than 0.1 percent of the gross weight. The trap and its contents are allowed to cool to room temperature, while vented through a drying tube via the outlet arm, before use

(2) Auxilliary collection equipment. (i) Drying tube-transparent, tubular body 3/4 inch ID, 6 inches long, with serrated tips and removable caps.

(ii) Desiccant-indicating variety, 8 mesh. The drying tube is attached to the outlet tube of the collection traps to prevent ambient moisture from entering the trap. It is prepared by filling the empty drying tube with fresh desiccant using loose wad of glass wool to hold the desiccant in place. The desiccant is renewed when three-quarters spent, as indicated by color change.

(iii) Collection tubing-stainless steel or aluminum, 16 inch ID, for connecting the collection traps to the fuel system vents.

(iv) Polyvinyl chloride (vinyl) tubing-flexible tubing, 16 inch ID, for sealing butt-to-butt joints.

(v) Laboratory tubing-air tight flexible tubing 16 inch ID, attached to the outlet end of the drying tubes to equalize collection system pressure.

(vi) Clamps-hosecock, open side, for pinching off flexible tubing.

(c) Weighing equipment. The balance and weights used shall be capable of determining the net weight of the activated carbon trap within an accuracy of +75 mg.

(d) Temperature measuring equipment. (1) Temperature recorder-multichannel, variable speed, potentiometric, or substantially equivalent, recorder with a temperature range of 50° F. to 100° F. and capable of either simultaneous or sequential recording of the ambient air and fuel temperatures within an accuracy of ±1° F.

(2) Fuel tank thermocouples-ironconstantan (type J) construction.

(e) Assembly and use of the activated carbon vapor collection system. (1) The

50-100-71-31

prepared activated carbon trap, dried to constant weight, cooled to the ambient temperature and sealed with clamped sections of vinyl tubing is carefully weighed to the nearest 20 milligrams and the weight recorded as the "tare weight."

(2) A drying tube is attached to the outlet tube and the clamp released, but not removed. A length of flexible tubing, for pressure equalization, is connected to the other end of the drying tube.

(3) The inlet tube of the adsorption trap and external vent(s) of the fuel system will be connected by minimal lengths of stainless steel or aluminum tubing and short sections of vinyl tubing. Buttto-butt joints shall be made wherever possible and precautions taken against sharp bends in the connection lines, including any manifold systems employed to connect multiple vents to a single trap.

(4) The clamp on the inlet tube of the trap shall be released but not removed. Care shall be exercised to prevent heating the vapor collection trap by radiant or conductive heat from the engine.

(5) Upon completion of the collection sequence, the vinyl tubing sections on each arm of the collection trap shall be clamped tight and the collection system dismantled.

(6) The sealed vapor collection trap shall be weighed carefully to the nearest 20 milligrams. This constitutes the "gross weight," which is appropriately recorded. The difference between the "gross weight" and "tare weight" represents the "net weight" for purposes of calculating the fuel vapor losses.

§ 1201.83 Information to be recorded. The following information shall be recorded with respect to each test:

(a) Test number.

(b) System or device tested (brief description).

(c) Date and time of day for each part of the test schedule.

(d) Instrument operator.

(e) Driver or operator.

(f) Vehicle: Make-Vehicle identification number-Model year-Transmission type-Odometer reading-Engine displacement-Engine family-Idle r.p.m.Nominal fuel tank capacity and location on vehicle-Number of carburetorsNumber of carburetor barrels-Inertia loading-Actual road load HP. at 50 m.p.h. and drive wheel tire pressure.

(g) Dynamometer serial number and indicated road load power absorption at 50 m.p.h.

(h) All pertinent instrument information such as tuning-gain-serial numbers-detector numbers-range.

(i) Recorder charts: Identify zero, span, exhaust gas, and dilution air sample traces.

(j) Barometric pressure, ambient temperature and humidity and the temperature of the air in front of the radiator, if any, during the test.

(k) Fuel temperatures, as prescribed. (1) The temperature and pressure of the mixture of exhaust and dilution air entering the positive displacement pump and the pressure increase across the pump. The temperature of the mixture shall be recorded continuously during the test.

(m) The number of revolutions of the positive displacement pump accumulated while the test is in progress and exhaust flow samples are being collected.

§ 1201.84 Analytical system calibration and sample handling.

(a) Calibrate HC and CO instrument assembly at least once every 30 days. Use the same flow rate as when analyzing samples.

(1) Adjust analyzers to optimize performance.

(2) Zero on prepurified air, i.e., less than 6 p.p.m. carbon equivalent of hydrocarbon and 10 p.p.m. of carbon monoxide. Check each cylinder of prepurified air for contamination with hydrocarbons and carbon monoxide.

(3) Set the CO analyzer gain to give the desired range. Select the desired attenuation scale of the HC analyzer and set the sample flow rate to give the desired range. The operating range of the analyzers shall be such that the analyzer deflection which indicates an emission level equivalent to the respective standards is in the upper two-thirds of the scale.

(4) Calibrate the HC analyzer with propane (prepurified air diluent) gases having nomina: concentrations equivalent to 50 and 100 percent of scale. Calibrate the CO analyzer with carbon monoxide (nitrogen diluent) gases which are equivalent to 10, 25, 40, 50, 60, 70, 85, and 100 percent of scale. The actual concentrations should be known to within ±2 percent of the true values.

(5) Compare values obtained on the CO analyzer with previous calibration curves. Any significant change reflects some problem in the system. Locate and correct problem, and recalibrate. Use best

judgment in selecting curve for data reduction.

(b) HC and CO measurements: Allow a minimum of 20 minutes warmup for the HC analyzer and 2 hours for the CO analyzer. (Power is normally left on infrared analyzers continuously; but when not in use, the chopper motor is turned off.) The following sequence of operations should be performed in conjunction with each series of measurements:

(1) Zero on prepurified air. Obtain a stable zero on the amplifier meter and recorder. Recheck after test.

(2) Introduce span gas and set the CO analyzer gain and HC analyzer sample flow rate to match calibration curves. In order to avoid correction for samplecell pressure, span and calibrate at the same filcw rates used to analyze the test samples. Span gases should have concentrations equivalent to approximately 80 percent of full scale. If gain has shifted significantly on the CO analyzer, check tuning. If necessary, check calibration. Recheck after test. Show actual concentrations on chart.

(3) Check zero, using prepurified air; repeat the procedure in subparagraphs (1) and (2) of this paragraph if required.

(4) Check flow rates and pressures. (5) Measure HC and CO concentration of samples. Care should be exercised to prevent moisture from condensing in the sample collection bag.

(6) Check zero and span points. § 1201.85 Dynamometer test runs.

(a) The vehicle shall be allowed to stand with engine turned off for a period of not less than 12 hours before the exhaust emission test, at an ambient temperature as specified in §§ 1201.73 and 1201.74. The vehicle shall be stored prior to the emission tests in such a manner that precipitation (e.g., rain or dew) does not occur on the vehicle. During the run the ambient temperature shall be between 68° F. and 86° F. For exhaust emission testing which is unrelated to fuel evaporative emission control, the ambient temperature requirement during storage shall be between 60° F. and 86° F. (b) The following steps shall be taken for each test:

(1) Place drive wheels of vehicle on dynamometer without starting engine. (2) Start the cooling fan with the vehicle engine compartment cover open.

(3) With the sample solenoid valves in the "dump" position, connect evacuated sample collection bags to the dilute

exhaust sample and the dilution air sample line connectors.

(4) Start the positive displacement pump, the sample pumps and the temperature recorder. (The heat exchanger of the constant volume sampler should be preheated to its operating temperature before the test begins.)

(5) Adjust the sample flow rates to the desired flow rate (minimum of 5 c.f.h.).

(6) Attach the flexible exhaust tube to the vehicle tailpipe(s).

(7) Simultaneously start the revolution counter for the positive displacement pump, position the sample solenoid valves to direct the sample flows into the bags, and start cranking the engine.

(8) Fifteen seconds after the engine starts, place the transmission in gear.

(9) Twenty seconds after the engine starts, begin the initial vehicle acceleration of the driving schedule.

(10) Operate the vehicle according to the dynamometer driving schecule.

(§ 1201.75.)

(11) Five seconds after the last deceleration, simultaneously turn off the

revolution counter and position the sample solenoid valve to the "dump" position.

(12) Immediately disconnect sample bags, transfer to analytical system and process samples according to § 1201.84 as soon as practicable, and in no case longer than 10 minutes after the dynamometer run.

(13) Disconnect the exhaust tube from the vehicle tailpipe(s) and remove vehicle from dynamometer.

(14) Turn off the positive displacement pump.

§ 1201.86 Chart reading.

(a) Determine the HC and CO concentrations of the dilution air and dilute exhaust sample bags from the instrument deflections or recordings making use of appropriate calibration charts.

(b) Determine the average dilute exhaust mixture temperature from the temperature recorder trace.

(2) Carbon Monoxide Mass:

(b) For off-road utility vehicles:

(c) Meaning of symbols:

HCcone 1,000,000

COcone 100

HCcond

1,000,000

COcone X 0.85 100

cone X 0.85

(c) Meaning of symbols-Continued

HCmass Densityнс

Comass Densityco

COcone=

=

The net weights of the individual collection traps employed in § 1201.74 shall be added together to determine compliance with the fuel evaporative emission standard.

§ 1201.89 Test vehicles.

(a) (1) The vehicles covered by the application for certification will be divided into groupings of vehicles whose engines are expected to have similar emission characteristics. Each group of engines with similar emission characteristics shall be defined as a separate engine family.

(2) To be classed in the same engine family, engines must be identical in all the following respects:

(i) The cylinder bore center to center dimensions.

(ii) The dimension from the centerline of the crankshaft to the centerline of the camshaft.

(iii) The dimension from the centerline of the crankshaft to the top of the cylinder block head face.

(iv) The cylinder block configuration (air-cooled or water-cooled; L-6, 90° V-8, etc.).

(v) The location of intake and exhaust valves and the valve sizes (within a 8inch range on the valve head diameter). (vi) The method of air aspiration. (vii) The combustion cycle.

(3) Engines identical in all the respects listed in subparagraph (2) of this paragraph may be further divided into different engine families if the Secretary determines that they may be expected to have different emission characteristics. This determination will be based upon a consideration of the following features of each engine:

(i) The bore and stroke.

(ii) The surface to volume ratio of the nominally dimensioned cylinder at the top dead center position.

(iii) The intake manifold induction port size and configuration.

(iv) The exhaust manifold port size and configuration.

(v) The intake and exhaust valve sizes.

(vi) The fuel system.

(vii) The camshaft timing and ignition timing characteristics.

(4) Where engines are of a type which cannot be divided into engine families based upon the criteria listed in subparagraph (2) and (3) of this paragraph, the Secretary will establish families for those engines based upon the features most related to their emission characteristics. (b) Emission data vehicles:

(1) Vehicles will be chosen to be operated and tested for emission data based upon the engine family groupings. Within each engine family, the requirements of this paragraph must be met.

(2) Vehicles of each engine family will be divided into engine displacement