frared analyzers are turned off and the phototube high voltage supply of the chemiluminescence analyzer is placed in the standby position.) The following sequence of operations should be performed in conjunction with each series of measurements:

(1) Zero the analyzers. Obtain a stable zero on each amplifier meter and recorder. Recheck after tests.

(2) Introduce span gases and set the CO and CO, analyzer gains, the HC analyzer sample capillary flow rate and the NO, analyzer high voltage supply or amplifier gain to match the calibration curves. In order to avoid corrections, span and calibrate at the same flow rates used to analyze the test samples. Span gases should have concentrations equal to approximately 80 percent of full scale. If gain has shifted significantly on the CO or CO2 analyzers, check tuning. If necessary, check calibration. Recheck after test. Show actual concentrations on chart.

(3) Check zeroes; repeat the procedure in subparagraphs (1) and (2) of this paragraph if required.

(4) Check flow rates and pressures. (5) Measure HC, CO, CO2, and NO, concentrations of samples. Care should be exercised to prevent moisture from condensing in the sample collection bag. (6) Check zero and span points. (c) For the purposes of this section, the term "zero grade air" includes artificial "air" consisting of a blend or nitrogen and oxygen with oxygen concentrations between 18 and 21 mole percent. § 85.075-24 Dynamometer test runs.

(a) The vehicle shall be allowed to stand with the engine turned off for a period of not less than 12 hours before the cold start exhaust emission test, at an ambient temperature as specified in §§ 85.075-12 and 85.075-13. 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. The complete dynamometer test consists of a cold start drive of 7.5 miles and simulates a hot start drive of 7.5 miles. The vehicle is allowed to stand on the dynamometer during the 10-minute time period between the cold and hot start tests. The cold start test is divided into two periods. The first period, representing the cold start "transient" phase, terminates at the end of the deceleration which is scheduled to occur at 505 seconds of the driving schedule. The second

period, representing the "stabilized" phase, consists of the remainder of the driving schedule including engine shutdown. The hot start test similarly consists of two periods. The first period, representing the hot start "transient" phase, terminates at the same point in the driving schedule as the first phase of the cold start test. The second period of the hot start test, "stabilized” phase, is assumed to be identical to the second period of the cold start test. Therefore, the hot start test terminates after the first period (505 seconds) is run. During the tests the ambient temperature shall be between 68° 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) Open the vehicle engine compartment cover and start the cooling fan.

(3) With the sample solenoid valves in the "dump" position connect evacuated sample collection bags to the two dilute exhaust sample connectors and to the two dilution air sample line connectors.

(4) Start the positive displacement pump (if not already on), 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 10 c.f.h.) and set the revolution counters to zero.

(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 flow into the "transient" exhaust sample bag and the "transient" dilution air sample bag, 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 schedule

($85.075-14).

(11) At the end of the deceleration which is scheduled to occur at 505 seconds, simultaneously switch the sample flows from the "transient" bags to the "stabilized" bags, switch off revolution counter No. 1 and start counter No. 2. As soon as possible and in no case longer

than 20 minutes after the end of this portion of the test disconnect the "transient" exhaust and dilution air sample bags, transfer them to the analytical system and process the samples according to § 85.075-23.

(12) Turn the engine off 2 second after the end of the last deceleration (at 1,369 seconds).

(13) Five seconds after the engine stops running, simultaneously turn off revolution counter No. 2 and position the sample solenoid valves to the "dump" position. As soon as possible and in no case longer than 20 minutes after the end of this portion of the test disconnect the "stabilized" exhaust and dilution air sample bags, transfer them to the analytical system and process the samples according to § 85.075-23.

(14) Immediately after the end of the sample period turn off the cooling fan and close the engine compartment cover.

(15) Immediately after the end of the sample period, disconnect the exhaust tube from the tailpipe(s), turn off the cooling fan and close the engine compartment cover.

(16) Turn off the positive displacement pump.

(17) Repeat the steps in subparagraphs (2) through (10) of this paragraph for the hot start test except only one evacuated sample bag is required for sampling exhaust gas and one for dilution air. The step in subparagraph (7) of this paragraph shall begin between 9 and 11 minutes after the end of the sample period for the cold start test.

(18) At the end of the deceleration which is scheduled to occur at 505 seconds, simultaneously turn off the No. 1 revolution counter and position the sample solenoid valve to the "dump" position. (Engine shutdown is not part of the hot start test sample period.)

(19) As soon as possible and in no case longer than 20 minutes after the end of this portion of the test disconnect the hot start "transient" exhaust and dilution air sample bags, transfer them to the analytical system and process the samples according to § 85.075-23.

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

(21) The positive displacement pump may be turned off, if desired.

Oxides of nitrogen emissions, in grams per test phase. Density of oxides of nitrogen in the exhaust gas, assuming they are in the form of nitrogen dioxide, in grams per cubic foot at 68° F. and 760 mm. Hg pressure (54.16 gm./cu. ft.).

V. Volume of gas pumped by the positive displace ment pump, în cubic feet per revolution. This volume is dependent on the pressure differential across the positive displacement pump. N-Number of revolutions of the positive displace ment pump during the test phase while samples are being collected.

PB Barometric pressure in mm. Hg. P-Pressure depression below atmosphere measured at the inlet to the positive displacement pump. T-Average temperature of dilute exhaust entering positive displacement pump during test while samples are being collected, in degrees Rankine. KH-Humidity correction factor.

1

1-0.0047 (H-74)

H-Absolute humidity in grains of water per pound of dry air.

H=

(43.478) RXPa

PB-(P&XR./100)

Relative humidity of the ambient air, in percent. Pa Saturated vapor pressure, in mm. Hg at the ambient dry bulb temperature.

(d) Example calculation of mass emission values:

(1) For the "transient" phase of the cold start test assume V. 0.29344 cu. ft. per revolution; N=10,485; R=48.0%; R. 48.2%; P=762 mm. Hg; P=22.225 mm. Hg; P=70 mm. Hg; T,=570°R; HC, 105.8 p.p.m. carbon equivalent; NO. 11.2 p.p.m.; CO.m=306.6 p.p.m.; CO2e=1.43%; HC=12.1 p.p.m.; NO1 =0.8 p.p.m.; CO&m=15.3 p.p.m. Then:

2595.0 cu. ft. per test phase.

=

§ 85.075-27 Calculations (fuel evaporative emissions).

The net weights of the individual collection traps employed in § 85.075-13 shall be added together to determine compliance with the fuel evaporative emission standard.

§ 85.075-28 Compliance with emission standards.

(a) The exhaust and fuel evaporative emission standards in § 85.075-1 apply to the emissions of vehicles for their useful life.

(b) Since emission control efficiency decreases with mileage accumulated on the vehicle, the emission level of a vehicle which has accumulated 50,000 miles will be used as the basis for determining compliance with the standards.

(c) The procedure for determining compliance of a new light duty motor vehicle with exhaust and fuel evaporative emission standards is as follows:

(1) Separate emission deterioration factors shall be determined from the emission results of the durability vehicle for each engine-system combination. A separate factor shall be established for exhaust HC, exhaust CO, exhaust NOx, and fuel evaporative HC.

(i) The applicable results to be used in determining the deterioration factors for each combination shall be:

(a) All valid emission data from the tests required under § 85.075-7(b),

factor=

ex

cept the zero mile tests. This shall include the official test results, as determined in § 85.075-29, for all tests conducted on all durability vehicles of the combination selected under § 85.075-5 (c) (including all vehicles elected to be operated by the manufacturer under § 85.075-5(c) (3)).

(b) All emission data from the tests conducted before and after the scheduled maintenance provided in §§ 85.075-6(a) (1) (i), (1) (iii), (3), (4), and (5) (iii).

(c) All emission data from tests required by maintenance approved under $85.075-6 (a) (1) (ix), in those cases where the Administrator conditioned his approval for the performance of such maintenance on the inclusion of such data in the deterioration factor calculation.

(ii) All applicable results shall be plotted as a function of the mileage on the system, rounded to the nearest mile, and the best fit straight lines, fitted by the method of least squares, shall be drawn through all these data points. The interpolated 4,000- and 50,000-mile points on this line must be within the standards provided in § 85.075-1 or the data will not be acceptable for use in calculation of a deterioration factor, unless no applicable data point exceeded the standard.

(iii) An exhaust emission deterioration factor shall be calculated for each combination as follows:

These interpolated values shall be carried out to a minimum of four places to the right of the decimal point before dividing one by the other to determine the deterioration factor. The results shall be rounded to three places to the right of the decimal point in accordance with ASTM E 29-67.

(iv) An evaporative emission deterioration factor shall be calculated for each combination by subtracting the evaporative emissions interpolated to 4,000 miles from the evaporative emissions interpolated to 50,000 miles. These inter

polated values shall be carried out, in accordance with ASTM E 29-67, to a minimum of three decimal places to the right of the decimal point before subtracting one from the other to determine the deterioration factor.

(2) (i) The exhaust emission test results for each emission data vehicle shall be multiplied by the appropriate deterioration factor: Provided, That if a deterioration factor as computed in paragraph (c) (1) (iii) is less than one, that deterioration factor shall be one for the purposes of this paragraph.

(ii) The evaporative emission test results for each combination shall be adjusted by addition of the appropriate deterioration factor: Provided, That if a deterioration factor as computed in paragraph (3) (1) (iv) is less than zero, that deterioration factor shall be zero for the purposes of this paragraph.

(3) The emissions to compare with the standard shall be the adjusted emissions of paragraph (c) (2) (i) and (ii) for each emission data vehicle. Before any emission value is compared with the standard, it shall be rounded, in accordance with ASTM E 29-67, to two significant figures. The rounded emission values may not exceed the standard.

(4) Every test vehicle of an engine family must comply with all applicable standards, as determined in paragraph (c) (3), before any vehicle in that family may be certified.

§ 85.075-29 Testing by the Administra

tor.

(a) The Administrator may require that any one or more of the test vehicles be submitted to him, at such place or places as he may designate, for the purpose of conducting emissions tests. The Administrator may specify that he will conduct such testing at the manufacturer's facility, in which case instrumentation and equipment specified by the Administrator shall be made available by the manufacturer for test operations. Any testing conducted at a manufacturer's facility pursuant to this paragraph shall be scheduled by the manufacturer as promptly as possible.

(b) (1) Whenever the Administrator conducts a test on a test vehicle, the results of that test, unless subsequently invalidated by the Administrator, shall comprise the official data for the vehicle at that prescribed test point and the manufacturer's data for that prescribed test point shall not be used in determining compliance with emission standards.

(2) Whenever the Administrator does not conduct a test on a test vehicle at a test point, the manufacturer's test data will be accepted as the official data for that test point: Provided, That if the Administrator makes a determination based on testing under paragraph (a) of this section, that there is a lack of correlation between the manufacturer's test equipment and the test equipment used by the Administrator; no manufacturer's test data will be accepted for purposes of certification until the reasons for the

lack of correlation are determined and the validity of the data is established by the manufacturer.

(3) (i) The emission data vehicle presented to the Administrator for testing shall be calibrated within the production tolerances applicable to the manufacturer's specifications to be shown on the vehicle label (see § 85.075–35 (a) (4) (iv)) as specified in the application for certification. If the Administrator determines that a vehicle is not within such tolerances, the vehicle shall be adjusted at the facility designated by the Administrator prior to the test and an engineering report shall be submitted to the Administrator describing the corrective action taken. Based on the engineering report, the Administrator will determine if the vehicle shall be used as an emission data vehicle.

(ii) If the Administrator determines that the test data developed under paragraph (b) (3) (i) would cause the emission data vehicle to fail due to excessive 4,000 mile emissions or by application of the appropriate deterioration factor, then the following procedure shall be observed:

(a) The manufacturer may request a retest. Before the retest, the vehicle may be readjusted to manufacturer's specifications, if these adjustments were made incorrectly prior to the first test, and other maintenance or repairs may be performed in accordance with § 85.075-6. All work on the vehicle shall be done at such location and under such conditions as the Administrator may prescribe.

(b) The vehicle will be retested by the Administrator and the results of this test shall comprise the official data for the emission data vehicle.

(4) If sufficient durability data are not available at the time of any emission test conducted under paragraph (a) of this section, to enable the Administrator to determine whether an emission data vehicle would fail, the manufacturer may request a retest in accordance with the provisions of paragraphs (c) (3) (i) (a) and (b) of this paragraph. If the manufacturer does not promptly make such request, he shall be deemed to have waived the right to a retest. A request for retest must be made before the manufacturer removes the vehicle from the test premises.

§ 85.075-30 Certification.

(a) (1) If, after a review of the test reports and data submitted by the manu