(2) Figure 2 represents an arrangement for collecting losses which emanate from the carburetor. Figure 3 depicts the means for separately collecting the vapors which emanate from the fuel tank vent line and filler cap. Figure 4 shows an arrangement for collecting the losses from a closed fuel system, vented to the atmosphere solely through the air cleaner, as might be the case with certain fuel evaporative emission control devices. (3) Schematic drawings of arrangements to be employed shall be submitted in accordance with § 85.51(b)(3).

(b) Collection equipment. The following equipment shall be used for this collection of fuel evaporative emissions. (Item quantities are determined by individual test needs.)

(1) Activated carbon trap. See Figure 5 for specifications of one design; other configurations may be used: Provided, That they give demonstrably equivalent results.

(i) Canister-300±25 ml., cylindrical container having a length to diameter

ratio of 1.4±0.1. An inlet tube, inch ID and 1 inch long is sealed into the top of the canister, at its geometric center. A similar outlet tube is sealed into the wall 1/4 inch from the bottom of the canister. The canister is designed to withstand an air pressure of 2 p.s.i., when sealed, without evidence of leaking when immersed in water for 30 seconds.

(ii) Activated carbon-meeting the following specifications:

Surface area, min. (N2 1,000 square meters BET method).1

per gram.

60 percent, by weight.

None.

Percent

90-100

The activated carbon trap is prepared for the test by attaching clamped sections of vinyl tubing to the inlet and outlet tubes of the canister. The canister is then filled with 150±10 gm. hot activated carbon which had previously been ovendried for 3 hours at 300° F. Loss of carbon through the inlet and outlet tubes is prevented through the use of wire screens of 0.7 mm. mesh or wads of loosely packed glass wool. The canister is closed immediately after filling and the carbon is allowed to cool while the trap is vented through a drying tube via the unclamped outlet arm.

(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 46 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 de

termining 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.

(3) Other types of thermocouples and recording equipment may be used provided they record the information specified in subparagraph (1) of this paragraph with the required accuracy and are self-contained. Type J thermocouples are required to be compatible with recording instruments used in Federal certification facilities.

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

(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 (from 6 to 12 inches from the grill) of the radiator 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 increases across the pump. The temperature of the mixture shall be recorded continuously or digitally at a rate often enough to determine temperature variations, or it may be controlled to ±5° F. of the set point of the temperature control system. In the last case only the set point need be recorded.

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

(n) The humidity of the dilution air.

§ 85.84 Analytical system

and sample handling.

calibration

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

(1) Adjust analyzers to optimize performance.

(2) Zero the hydrocarbon analyzer with zero grade air and the carbon monoxide, carbon dioxide, and oxides of nitrogen analyzers with zero grade nitrogen. The allowable zero gas impurity concentrations should not exceed 1 p.p.m. equivalent carbon response, 1 p.p.m. carbon monoxide, 300 p.p.m. (0.03 mole percent) carbon dioxide, and 0.1 p.p.m. nitric oxide.

(3) Set the CO and CO2 analyzer gains to give the desired ranges. Select the desired attenuation scale of the HC analyzer and set the sample capillary flow rate, by adjusting the back pressure regulator, to give the desired range. Select the desired scale of the NO, analyzer and adjust the phototube high voltage supply to give the desired range.

(4) Calibrate the HC analyzer with propane (air diluent) gases having nominal concentrations equal to 50 and 100 percent of full scale. Calibrate the CO analyzer with carbon monoxide (nitrogen diluent) gases and the CO2 analyzer with carbon dioxide (nitrogen diluent) gases having nominal concentrations equal to 10, 25, 40, 50, 60, 70, 85, and 100 percent of full scale. Calibrate the NOx analyzer with nitric oxide (nitrogen diluent) gases having nominal concentrations equal to 50 and 100 percent of full scale. The actual concentrations should be known to within ±2 percent of the true values.

(5) Compare values obtained on the CO and CO2 analyzers with previous calibration curves. Any significant change reflects some problem in the system. Locate and correct problem, and recalibrate. Use best judgment in selecting curves for data reduction.

(6) Check the NOx to NO converter efficiency by the following procedure:

(i) Fill a new (not previously used to collect exhaust gas samples) sample bag with air (or oxygen) and NO span gas in proportions which result in a mix in the operating range of the analyzer. Provide enough oxygen for substantial conversion of NO to NO2.

(ii) Knead bag and immediately connect the bag to the sample inlet and alternately measure the NO and NO, concentration at 1-minute intervals by alternately passing the sample through the converter and the bypass (close valves N6 and N10 to minimize pump down rate of bag). After several minutes of operation, the recording of NO and NO will resemble Figure lc if the converter is efficient. Even though the