RECOMMENDED PRACTICE for DETERMINATION OF EVAPORATIVE EMISSIONS from LIGHT DUTY VEHICLES sszz U.S. ENVIRONMENTAL PROTECTION AGENCY OFFICE OF AIR AND WASTE MANAGEMENT MOBILE SOURCE AIR POLLUTION CONTROL OCTOBER 1975 ------- 420R75104 Recommended Practice for Determining Exhaust and Evaporative Emissions from Light Duty Vehicles and Trucks October, 1975 ------- Table of Contents Section 105 Introduction; structure of subpart 1 106 Equipment required; overview 1 107 Sampling and analytical system, evaporative emissions 2 108 Dynamometer 2 109 Exhaust Gas sampling system 2 110 Exhaust Gas analytical system 5 111 Fuel specifications 6 112 Analytical gases 8 113 EPA Urban Dynamometer Driving Schedule. . . .9 114 Calibrations, frequency and overview. . 9 115 Evaporative emission enclosure calibrations. .10 116 Dynamometer calibration 13 117 Constant volume samper calibration 14 118 Hydrocarbon analyzer calibration 21 119 Carbon monoxide analyzer calibration 22 120 Oxides of nitrogen analyzer calibration. . . .23 121 Carbon dioxide analyzer calibration 25 122 Calibration of other equipment 25 123 Test procedures, overview 25 124 Transmissions 26 125 Road load power and inertia weight determination 27 -i- ------- 126 Test sequence, general requirements 29 127 Vehicle preparation 29 128 Vehicle preconditioning. . . 29 129 Diurnal breathing loss test 30 130 Running loss test 32 131 Dynamometer procedure. . . 32 132 Engine starting and restarting 3;3 133 Dynamometer test runs 35 134 Hot soak test 37 135 Exhaust sample analysis 38 136 Records required 39 137 Calculations; evaporative emissions 40 138 Calculations; exhaust emissions 41 -11- ------- 105 Introduction, structure of Recommended Practice (a) This Recommended Practice describes the equipment required and the procedures to follow in order to perform exhaust and evapora- tive emission tests on light duty vehicles and light duty trucks. (b) Three topics are addressed in this Recommended Practice. Sections 106 through 113 set forth specifications and equipment re- quirements; sections 114 through 122 discuss calibration methods and frequency; test procedures and data requirements are listed (in approximately chronological order) in sections 123 through 139. (c) References to the Federal Register pertain to Part 86 Volume 40, No. 126. 106 Equipment required; overview. (a) This section contains procedures for both exhaust and evaporative emissions tests on gasoline or diesel fueled light duty vehicles and light duty trucks. Certain items of equipment are not necessary for a particular test, e.g., evaporative enclosure when testing diesel vehicles. Equipment required and specifications are as follows: (1) Evaporative emission tests, gasoline fueled vehicles. The evaporative emission test is closely related to and connected with the exhaust emission test. All vehicles tested for evaporative emissions must be tested for exhaust emissions. (Diesel vehicles are excluded from the evaporative emission test.) Section 107 specifies the necessary equipment. (2) Exhaust emission tests. Diesel and gasoline fueled vehicles are tested identically with the exception of hydrocarbon measurements; diesel vehicles require a heated hydrocarbon detector, section 109. All gasoline fueled vehicles are either tested for evaporative emis- sions or undergo a diurnal heat build, diesel vehicles are excluded from this requirement. Equipment necessary and specifications appear in sections 108 through 112. (3) Fuel, analytical gas, and driving schedule specifications. Fuel specifications for exhaust and evaporative emission testing and for mileage accumulation for gasoline and diesel fueled vehicles are specified in 111. Analytical gases are specified in 112. The EPA Urban Dynamometer Driving Schedule for use in exhaust testing is specified in 113 and Appendix I of the Federal Register. -1- ------- 107 Sampling and analytical system, evaporative emissions. (a) Component description (evaporative emissions sampling system). The following components will be used in evaporative emis- sions sampling systems for testing under this Recommended Practice. (1) Evaporative emission measurement enclosure. The enclosure shall be large enough to accommodate the largest vehicle to be tested, with space for personnel access to all sides of the vehicle. The enclosure door must allow entry of the maximum size vehicle. When sealed, the enclosure shall be gas tight. Interior surfaces must be impermeable to hydrocarbons. One surface should be of flexible, impermeable material to allow for minor volume changes, resulting from temperature changes. To maximize dissipation of heat, wall materials should be of minimum thermal resistance. (2) Evaporative emission hydrocarbon analyzers. A hydrocarbon analyzer utilizing the hydrogen flame ionization principle (FID) shall be used to monitor the atmosphere within the enclosure. The FID shall have a minimum full scale measuring sensitivity of 5 ppm propane with a stability of + 1% of range, a reproducibility of + 1% of range and a response to 90% of final reading within 1.5 s. Sufficient ranges will be available, such that any reading will fall within the upper 80% of the range in use. (3) Evaporative emission hydrocarbon data recording system. The electrical output of the FID shall be recorded at the initiation and termination of each diurnal or hot soak. The recording may be by means of a strip chart potentiometric recorder, by use of an on-line computer system or other suitable means. In any case, the recording system must have operational characteristics (signal to noise ratio, speed of response, etc.) equivalent to or better than those of the signal source being recorded, and must provide a permanent record of results. The recording system must provide a positive indication of the initiation and completion of each diurnal or hot soak along with the time elapsed between initiation and completion of each soak. (4) Tank fuel heating system. The tank fuel heating system shall consist of a heat source and a temperature controller. A typical heat source is a 2000 w heating pad. Other sources may be used as required by circumstances. The temperature controller may be manual, such as a variable voltage transformer, or may be automated. The heating system must not cause hot spots on the tank wetted surface which could cause local overheating of the fuel. Heat must not be applied to the vapor in the tank above the liquid fuel. The tempera- ture controller must be capable of controlling the fuel tank temperature during the diurnal soak to within + 2°F (1.1°C) of the following equation: -2- ------- F = 60 + 0.4 t or for SI units: C = 15.556 + 2/9 t Where: F = Temperature in °F C = Temperature in °C t = Time since start of test in minutes (5) Temperature recording system. Strip chart recorder(s) or automatic data processor shall be used to record enclosure ambient and vehicle fuel tank temperature during the evaporative emissions test. The temperature recorder or data processor shall record each temperature at least once every minute. The recording system shall be capable of resolving time to + 15s and capable of resolving temperature to + 0.75°F (0.42°C). The temperature recording system (recorder and sensor) shall have an accuracy of + 2°F (1.1°C). The recorder (data processor) shall have a time accuracy of + 15s and a precision of + 15s. The ambient temperature sensor shall be located in the enclosure, within 6 inches (15 cm) of the geometric center of the ceiling and between 6 and 12 in. (15 and 30 cm) below the ceiling surface. The vehicle fuel tank temperature sensor shall be located in the fuel tank so as to measure the temperature of the prescribed test fuel at its approximate mid-volume of the fuel. Vehicles furnished for testing shall be equipped with copper-constantan Type T thermocouples for measurement of fuel tank temperature. (6) Purge blower. One or more portable or fixed blowers shall be used to purge the enclosure. The blowers shall have sufficient flow capacity to reduce the enclosure hydrocarbon concentration from the test level to the ambient level between tests. Actual flow capacity will depend upon the time available between tests. (7) Mixing blower. One or more small blowers or fans shall be used to mix the contents of the enclosure during evaporative emission testing. Maintenance of uniform concentrations throughout the enclosure is important to the accuracy of the test. 108 Dynamometer. The dynamometer shall have a power absorbtion unit for simulation of road load power and flywheels or other means of simulating the inertia weight as specified in section 125. 109 Exhaust gas sampling system. (a) (1) Schematic drawings. Figure 1 is a schematic drawing of the Positive Displacement Pump - Constant Volume Sampler (PDP-CVS) and -3- ------- Figure 2 is a schematic drawing of the Critical Flow Venturi - Constant Volume Sampler (CFV-CVS). These are two suggested exhaust gas sampling systems. (2) Since various configurations can produce equivalent results, exact conformance with either drawing is not required. Additional components such as instruments, valves, solenoids, pumps, and switches may be used to provide additional information and coordinate the functions of the component systems. (3) Other Systems. Other sampling systems may be used if shown to yield equivalent results. (b) Component description, PDP-CVS. The PDP-CVS, Figure 1, consists of a dilution air filter and mixing assembly, heat exchanger, positive displacement pump, sampling system, and associated valves, pressure and temperature sensors. The PDP-CVS shall conform to the following requirements: (1) Static pressure variations at the tailpipe(s) of the vehicle shall remain within + 5 inches of water (1.2 kPa) of the static pressure variations measured during a dynamometer driving cycle with no connection to the tailpipe(s). (2) The gas mixture temperature, measured at a point immediately ahead of the positive displacement pump, shall be within + 10°F (5.6°C) of the designed operating temperature at the start of the test. The gas mixture temperature variation from its value at the start of the test shall be limited to + 10°F (5.6°C) during the entire test. The temperature measuring system shall have an accuracy and precision of + 2°F (1.1°C). (3) The pressure gauges shall have an accuracy and precision of + 3 mm Hg (0.4 kPa). (4) The flow capacity of the CVS shall be large enough to eliminate water condensation in the system (300 to 350 cfm, 0.142 to 0.165 m /s, is sufficient for most vehicles). (5) Sample collection bags for dilution air and exhaust samples shall be of sufficient size so as not to impede sample flow. (c) Component description, CFV-CVS. The CFV-CVS, Figure 2 consists of a dilution air filter and mixing assembly, cyclone particulate separator, sampling venturi, critical flow venturi, sampling system, and assorted valves, pressure and temperature sensors. The CFV-CVS shall conform to the following requirements: (1) Static pressure variations at the tailpipe(s) of the vehicle shall remain within + 5 inches of water (1.2 kPa) of the static pressure ------- AMBIENT AIR INLET TO DILUTION AIR SAMPLE BAG TO EXHAUST SAMPLE BAG POSITIVE DISPLACEMENT PUMP VEHICLE [ EXHAUST INLET FOR DIESEL HC ANALYSIS ONLY MANOMETER REVOLUTION COUNTER PICKUP DISCHARGE (SEE FIG. B78-3 FOR SYMBOL LEGEND) Figure 1 —EXHAUST GAS SAMPLING SYSTEM (PDP-CVS) ------- VEHICLE EXHAUST INLET + SAMPLING VENTURI CYCLONIC SEPARATOR PRECISION SENSOR TO DILUTION AIR SAMPLE BAG TO EXHAUST SAMPLE BAG SNUBBER ABSOLUTE PRESSURE TRANSDUCER CRITICAL FLOW VENTURI CVS COMPRESSOR UNIT CVS SAMPLER UNIT (SEE FIG. 3 FOR SYMBOL LEGEND) Figure 2 —EXHAUST GAS SAMPLING SYSTEM (CFV-CVS) ------- variations measured during a dynamometer driving cycle with no connection to the tailpipe(s). (2) The temperature measuring system shall have an accuracy and precision of + 2°F (1.1°C) and a response time of 0.100 s to 62.5% of a temperature change. (3) The pressure measuring system shall have an accuracy and precision of + 3 mm Hg (0.4 kPa). (4) The flow capacity of the CVS shall be large enough to eliminate water condensation in the system (300 to 350 cfm, 0.142 to 0.165 m /s, is sufficient for most vehicles). .' (5) Sample collection bags for dilution air and exhaust samples shall be of sufficient size so as not to impede sample flow. 110 Exhaust gas analytical system. (a) Schematic drawings. Figure 3 is a schematic drawing of the exhaust gas analytical system. The schematic of the hydrocarbon analysis train for diesel fueled vehicles is shown as part of Figure 1. Since various configurations can produce accurate results, exact conformance with either drawing is not required. Additional components such as instruments, valves, solenoids, pumps and switches may be used to provide additional information and coordinate the functions of the component systems. (b) Major component description. The analytical system, Figure 3, consists of a flame ionization detector (FID) for the determination of hydrocarbons, nondispersive infrared analyzers (NDIR) for the determination of carbon monoxide and carbon dioxide and a chemiluminescence analyzer (CL) for the determination of oxides of nitrogen. A heated flame ionization detector (HFID) is used for the continous determination of hydrocarbons from diesel fueled vehicles, Figure 1. The exhaust gas analytical system shall conform to the following requirements: (1) The chemiluminescence analyzer requires that the nitrogen dioxide present in the sample be converted to nitric oxide before analysis. Other types of analyzers may be used if shown to yield equivalent results. (2) The carbon monoxide (NDIR) analyzer may require a sample conditioning column containing CaSO,, or indicating silica gel to remove water vapor and containing ascarite to remove carbon dioxide from the CO analysis stream. (i) If CO instruments which are essentially free of C0« and water vapor interference are used, the use of the conditioning column may be deleted, see sections 119-and 138. -5- ------- TO SAMPLE BAG FOR DIESEL HC ANALYSIS SEE FIG. B78-1 OPEN TO ATMOSPHERE T V7 co -[NM fciM 0 SPAN 1^VI ^ GASES I O GAS T CO2 -IX] O SPAN GASES * © PR] § FLOW CONTROL VALVE SELECTOR VALVE PARTICULATE FILTER PUMP FLOWMETER PRESSURE GAUGE RECORDER TEMPERATURE SENSOR LOW CO CO2 NOx TO OUTSIDE VENT FIGURE 3 EXHAUST GAS ANALYTICAL SYSTEM AIR -O OR ------- (ii) A CO instrument will be considered to be essentially free of CO. and water vapor interference if its response to a mixture of 3 percent CO,, in N_ which has been bubbled through water at room tempera- ture produces an equivalent CO response, as measured on the most sensitive CO range, which is less than 1 percent of full scale CO concentration on ranges above 300 ppm full scale or less than 3 ppm on ranges below 300 ppm full scale, see section 119. (3) For diesel fueled vehicles a continuous sample shall be measured using a heated analyzer train as shown in Figure 1. The train shall include a heated continuous sampling line, a heated particulate filter and a heated hydrocarbon instrument (HFID) complete with heated pump, filter and flow control system. (i) The response time of this instrument shall be less than 1.5 seconds for 90 percent of full-scale response. (ii) Sample transport time from sampling point to inlet of instrument shall be less than 4 seconds. (iii) The sample line and filter shall be heated to a set point + 10°F (+ 5.6°C) between 300 and 390°F (149 and 199°C). (c) Other analyzers and equipment. Other types of analyzers and equipment may be used if shown to yield equivalent results. Ill Fuel Specifications. (a) Gasoline. Gasoline having the following specifications or substantially equivalent specifications shall be used in exhaust and evaporative testing. -6- ------- Item ASTM Leaded Unleaded Designation Octane, research, minimum D2699 1'OOr 96 Pb. (organic), grams/U.S. gallon 1.4 0.00-0.5 Distillation range: IBP , °F D86 75-95 75-95 10 percent point, °F D86 120-135 120-135 50 percent point, °F D86 200-230 200-230 90 percent point, °F D86 300-325 300-325 EP, °F (maximum) D86 415 415 Sulphur, weight percent, maximum—' D1266 0.10 .10 Phosphorus, grams/U.S. gallon, maximum .01 .005 RVP ' , pounds D323 8.7-9.2 8.7-9.2 Hydrocarbon composition Olefins, percent, maximum D1319 -10 10 Aeromatics, percent, maximum D1319 35 35 Saturates D1319 Remainder Remainder Minimum. 2 For testing at altitudes above 1,219 meters (4,000 feet) the specified range is 75-105. 3 For testing which is unrelated to evaporative emission control, the specified range is 8.0-9.2. 4 For testing at altitudes above 1,219 meters (4,000 feet) the specified range is 7.9-9.2. (3) The specification range of the gasoline to be used under paragraph (a)(2) of this section shall be reported. (b) Diesel fuel. (1) The diesel fuels employed for testing shall be clean and bright, with pour and cloud points adequate for operability. The diesel fuel may contain nonmetallic additives as follows: Centane improver, metal deactivator, antioxidant, dehazer, antirust, pour depresent, dye, and dispersant. (2) Diesel fuel meeting the following specifications, or substantially equivalent specifications shall be used in exhaust emissions testing. The grade of diesel fuel recommended by the engine manufacturer commercially designated as "Type 1-D" or "Type 2-D", shall be used. -7- ------- Item ASTM test Method No. Type 1-D Type 2-D Cetane D613 48-54 42-50 Distillation range D86 IBP, °F 330-390 340-400 10 percent point, °F 370-430 400-460 50 percent point, °F 410-480 470-540 90 percent point, °F 460-520 550-610 EP, °F 500-560 580-660 Gravity, °API D287 40-44 33-37 Total Sulfur, percent D129 or D2622 0.05-0.20 0.2-0.5 Hydrocarbon composition D1319 Aromatics, percent 8-15 27(min.) Paraffins, Naphthenes, Olefins Remainder Remainder Flashpoint °F (minimum) D93 120 130 Viscosity, Centistokes D445 1.6-2.0 2.0-3.2 (3) Other petroleum distillation fuel specifications: (i) Other petroleum distillate fuels may be used for testing provided they are commercially available, and (ii) Information is provided to show that only the designated fuel would be used in customer service, and (iii) Use of a fuel listed under paragraphs (b)(2) and (b)(3) of this section would have a detrimental effect on emissions or durability. (4) The specification range of the fuels to be used under paragraphs (b) (2) and (b) (3) of this section shall be reported. 112 Analytical gases. (a) Analyzer gases. (1) Gases for the CO and C02 analyzers shall be single blends of CO and CO,, respectively using nitrogen as the diluent. (2) Gases for the hydrocarbon analyzer shall be single blends of propane using air as the diluent. (3) Gases for NOx analyzer shall be single blends of NO named as rith a maximum NO,, concent] using nitrogen as the diluent. NOx with a maximum NO,, concentration of 5 percent of the nominal value (4) Fuel for the evaporative emission enclosure FID shall be a blend of 60 percent helium and 40 percent hydrogen containing less than 1 ppm equivalent carbon response. -8- ------- (5) The allowable zero gas (air or nitrogen) impurity concentrations shall not exceed 1 ppm equivalent carbon response, 1 ppm carbon monoxide, 0.04 percent (400 ppm) carbon dioxide and 0.1 ppm nitric oxide. (6) "Zero grade air" includes artificial "air" consisting of a blend of nitrogen and oxygen with oxygen concentrations between 18 and 21 mole percent. (b) Calibration gases shall be traceable to within 1 percent of NBS gas standards, or EPA gas standards or other approved gas standards. (c) Span gases shall be accurate to within 2 percent of true concentration, where true concentration refers to NBS gas standards, EPA gas standards or other approved gas standards. 113 EPA Urban Dynamometer Driving Schedule. (a) The dynamometer driving schedule is listed in Appendix I of the Federal Register. The driving schedule is defined by a smooth trace drawn through the specified speed vs. time relationships. It consists of a non-repetitive series of idle, acceleration, cruise, and deceleration modes of various time sequences and rates. (b) The speed tolerance at any given time on the dynamometer driving schedule prescribed in Appendix I or as printed on a driver's aid chart, when conducted to meet the requirements of section 133 is defined by upper and lower limits. The upper limit is 2 mph (3.2 kph) higher than the highest point on the trace within 1 second of the given time. The lower limit is 2 mph (3.2 kph) lower than the lowest point on the trace within 1 second of the given time. Speed variations greater than the tolerances (such as may occur during gear changes) are acceptable provided they occur for less than 2 seconds on any occasion. Speeds lower than those prescribed are acceptable provided the vehicle is operated at maximum available power during such occur- rences. When conducted to meet the requirements of section 128 the speed tolerance shall be as specified above, except that the upper and lower limits shall be 4 mph (6.4 kph). (c) Figure 4 shows the range of acceptable speed tolerances for typical points. Figures 4(a) is typical of portions of the speed curve which are increasing or decreasing throughout the two second time interval. Figure 4(b) is typical of portions of the speed curve which include a maximum or minimum value. 114 Calibrations, frequency and overview. (a) Calibrations shall be performed as specified in section 115 through 122. (b) At least yearly or after any maintenance, enclosure background emission measurements shall be performed. -9- ------- _c a CN a- E ^ Is -"- Is -*• ALLOWABLE RANGE t TIME FIGURE 4a -DRIVERS TRACE, ALLOWABLE RANGE ALLOWABLE RANGE TIME FIGURE 4b —DRIVERS TRACE, ALLOWABLE RANGE ------- (c) At least monthly or after any maintenance which could alter calibration, the following calibrations and checks shall be performed: (1) Calibrate the hydrocarbon analyzers (both evaporative and exhaust instruments), carbon dioxide analyzer, carbon monoxide analyzer, oxides of nitrogen analyzer. (2) Calibrate the dynamometer. If the dynamometer receives a weekly performance check (and remains within calibration) the monthly calibration need not be performed. (3) Perform a hydrocarbon retention check and calibration on the evaporative emission enclosure. (d) At least weekly or after any maintenance which could alter calibration, the following calibrations and checks shall be performed: (1) Check the oxides of nitrogen converter efficiency, and (2) Perform a CVS system verification, and (3) Run a performance check on the dynamometer. This check may be omitted if the dynamometer has been calibrated within the preceding month. (e) The CVS positive displacement pump or Critical Flow Venturi shall be calibrated following initial installation, major maintenance or as necessary when indicated by the CVS system verification (described in section 117). (f) Sample conditioning columns, if used in the CO analyzer train, should be checked at a frequency consistent with observed column life or when the indicator of the column packing begins to show deterioration. 115 Evaporative emission enclosure calibrations. The calibration of the evaporative emission enclosure consists of three parts: Initial and periodic determination of enclosure background emissions; initial determination of enclosure internal volume; and periodic hydrocarbon retention check and calibration. (a) Initial and periodic determination of enclosure background emissions. Prior to its introduction into service, annually thereafter, and after repair, the enclosure shall be checked to determine that it does not contain materials which will themselves emit hydrocarbons. Proceed as follows: -10- ------- (1) Zero and span (calibrate if required) the hydrocarbon analyzer. (2) Purge the enclosure until a stable background hydrocarbon reading is obtained. (3) Turn on the mixing blower (if not already on). (4) Seal enclosure and measure background hydrocarbon concentration, temperature and barometric pressure. These are the initial readings C..n., T. and PD. for the enclosure background determination. riCi i Hi (5) Allow the enclosure to stand undisturbed without sampling for four hours. (6) Measure the hydrocarbon concentration on the same FID. This is the final concentration, C „,-. Also measure final temperature and , . HL.I barometric pressure. (7) Calculate the mass change of hydrocarbons in the enclosure according to the equations in paragraph (d). The enclosure background emissions shall not be greater than 0.4g for the 4 hours. (b) Initial determination of enclosure internal volume. Prior to its introduction into service the enclosure internal volume shall be determined by the following procedure. (1) Carefully measure the internal length, width and height of the enclosure, accounting for irregularities (such as braces) and calculate the internal volume. (2) Perform an enclosure calibration check according to paragraph (c) steps (1) through (7). (3) If the calculated mass does not agree within 2% of the injected propane mass, then corrective action is required. (c) Hydrocarbon retention check and calibration. The hydrocarbon retention check provides a check upon the calculated volume and also measures the leak rate. Prior to its introduction into service and at least monthly thereafter the enclosure leak rate shall be determined as follows: (1) Zero and span (calibrate if required) the hydrocarbon analyzer. (2) Purge the enclosure until a stable background hydrocarbon reading is obtained. (3) Turn on the mixing blower (if not already on). -11- ------- (4) Seal enclosure and measure background hydrocarbon concentra- tion, temperature and barometric pressure. These are the initial readings Cu_., T. and P . for the enclosure calibration. HCi x Bi (5) Inject into the enclosure a measured quantity, (at least 15g) of pure propane. The propane may be measured by volume flow or by mass measurement. The method used to measure the propane shall have an accuracy and precision of + 0.5% of the measured value. (6) After a minimum of five minutes of mixing, analyze the enclosure atmosphere for hydrocarbon content, also record temperature and pressure. These measurements are the final readings for the enclosure calibration as well as the initial readings for the retention check. (7) To verify the enclosure calibration calculate the mass of propane using the measurements taken in steps (4) and (6). See para- graph (d). This quantity must be within + 2% of that measured in step 5 above. (8) Allow the enclosure to remain sealed for a minimum of four hours without sampling and with the mixing blower operating. After four hours analyze the enclosure atmosphere for hydrocarbon content; record temperature and barometric pressure. These are the final readings for the hydrocarbon retention check. (9) Calculate, using the equations in paragraph (d) and the readings taken in (6) and (8), the hydrocarbon mass change. It must be less than +0.4 g or the enclosure cannot be used. (d) Calculations. The calculation of net hydrocarbon mass change is used to determine enclosure background and leak rate. It is also used to check the enclosure volume measurements. The mass change is calculated from the initial and final readings of hydrocarbon concentration, temperature and pressure according to the following equation: = k V x 10 n -4 •• p p p 'HCf Bf - UHCi Bi Tf T. Where: VL,C = hydrocarbon mass change, g C = hydrocarbon concentration as ppm carbon 3 3 V = net enclosure volume, ft (m ), as measured in n (b)(l) above -12- ------- P - barometric pressure, in. Hg(kPa) B T = enclosure ambient temperature, R(K) k = 3.05 for SI units, k = 17.60 i = indicates initial reading f = indicates final reading NOTE: Hydrocarbon concentration is stated in ppm carbon, that is, ppm propane x3. Expressions in parenthesis are for SI units. 116 Dynamometer calibration. (a) The dynamometer shall be calibrated at least once each month or performance verified at least once each x^eek and then calibrated as required. The calibration shall consist of the manufacturer's recom- mended calibration procedure plus a determination of the dynamometer frictional power absorption at 50.0 mph (80.5 kph). One method for determining dynamometer frictional power absorption at 50.0 mph (80.5 kph) is described below, other methods may be used if shown to yield equivalent results. The measured absorbed road power includes the dynamometer friction as well as the power absorbed by the power absorption unit. The dynamometer is driven above the test speed range. The device used to drive the dynamometer is then disengaged from the dynamometer and the roll(s) is (are) allowed to coast down. The kinetic energy of the system is dissipated by the dynamometer. This method neglects the variations in roll bearing friction due to the drive axle weight of the vehicle. The difference in coastdown time of the free (rear) roll relative to the drive (front) roll may be neglected in the case of dynamometers with paired rolls. These procedures shall be followed: (1) Devise a method to determine the speed of the drive roll if it is not already measured. A fifth wheel, revolution pickup, or other suitable means may be used. (2) Place a vehicle on the dynamometer or devise another method of driving the dynamometer. (3) Engage the inertial flywheel or other inertial simulation system for the most common vehicle mass category for which the dynamo- meter is used. (4) Drive the dynamometer up to 50.0 mph (80.5 kph). (5) Record indicated road power. (6) Drive the dynamometer up to 60.0 mph (96.9 kph). -13- ------- (7) Disengage the device used to drive the dynamometer. (8) Record the time for the dynamometer drive roll to coastdown from 55.0 mph (88.5 kph) to 45 mph (72.4 kph). ' (9) Adjust the power absorption unit to a different level. (10) Repeat steps 4 to 9 above sufficient times to cover the range of road power used. (11) Calculate absorbed road power (HP,). See paragraph (c). (12) Plot indicated road load power at 50 mph (80.5 kph) versus road load power at 50 mph (80.5 kph) as shown in Figure 5. (b) The performance check consists of conducting a dynamometer coast-down at one inertia-horsepower setting and comparing the coast- down time to that recorded during the last calibration. If the coast- down times differ by more than 1 s, a new calibration is required. (c) Calculations. The road load power actually absorbed by the dynamometer is calculated from the following equation: HPd = (1/2) (W/32.2) (Vx2 - V22)/550t Where: HP = Power, horsepower, (kilowatts) W = Equivalent inertia, Ib (Kg) V = Initial Velocity, ft/s (m/s) (55 mph = 88.5 kph = 80.67 ft/s = 24.58 m/s) V = Final Velocity, ft/s (m/s) (45 mph = 72.4 kph = 66 ft/s = 20.11 m/s) t = elapsed time for rolls to coast from 55 mph to 45 mph (88.5 kph to 72.4 kph) (Expressions in parenthesis are for SI units.). When the coast down is from 55 to 45 mph (88.5 to 72.4 kph) the above equation reduces to: HP = 0.06073 (W/t) for SI units, HP, = 0.09984 (W/t) d 117 CVS calibration. The CVS (Constant Volume Sampler) is calibrated using an accurate flowmeter and restrictor valve. Measurements of various parameters -14- ------- UJ 5 £ z o — i 30.0 20.0 10.0 10.0 20.0 30.0 40.0 ROAD LOAD HORSEPOWER AT 50 mph. FIGURE 5 —ROAD LOAD HORSEPOWER, ACTUAL VS. INDICATED ------- are made and related to flow through the unit. Procedures used by EPA for both PDF (Positive Displacement Pump) and CFV (Critical Flow Venturi) are outlined below. Other procedures yielding equivalent results may be used. After the calibration curve has been obtained, verification of the entire system can be performed by injecting a known mass of gas into the system and comparing the mass indicated by the system to the true mass injected. An indicated error does not necessarily mean that the calibration is wrong, since other factors can influence the accuracy of the system, e.g. analyzer calibration. A verification procedure is found in paragraph (c). (a) PDF calibration. (1) The following calibration procedure outlines the equipment, the test configuration, and the various parameters which must be measured to establish the flow rate of the constant volume sampler pump. All the parameters related to the pump are simultaneously measured with the parameters related to a flowmeter which is connected in series with the pump. The calculated flow rate ft /min. (at pump inlet absolute pressure and temperature) can then be plotted versus a correlation function which is the value of a specific combination of pump parameters. The linear equation which relates the pump flow and the correlation function is then determined. In the event that a CVS has a multiple speed drive, a calibration for each range used must be performed. (2) This calibration procedure is based on the measurement of the absolute values of the pump and flowmeter parameters that relate the flow rate at each point. Three conditions must be maintained to assure the accuracy and integrity of the calibration curve. First, the pump pressures should be measured at taps on the pump rather than at the external piping on the pump inlet and outlet. Pressure taps that are mounted at the top center and bottom center of the pump drive headplate are exposed to the actual pump cavity pressures, and there- fore reflect the absolute pressure differentials. Secondly, tempera- ture stability must be maintained during the calibration. The laminar flowmeter is sensitive to inlet temperature oscillations which cause the data points to be scattered. Gradual changes (+ 2°F (1.1°C)) in temperature are acceptable as long as they occur over a period of several minutes. Finally, all connections between the flowmeter and the CVS pump must be absolutely void of any leakage. (3) During an exhaust emission test the measurement of these same pump parameters enables the user to calculate the flow rate from the calibration equation. (4) Connect a system as shown in Figure 6. Although particular types of equipment are shown, other configurations that yield equivalent results may be used. -15- ------- CALIBRATION DATA MEASUREMENTS PARAMETER SYM UNITS TOLERANCES oBarometric pressure (corrected) oAmbient temperature ?! °Air temperature into LFE ETI "Pressure depression upstream of LFE EPI °Pressure drop across the LFE matrix EDP °Air temperature at CVS pump inlet PTI °Pressure depression at CVS pump inlet PPI °Specific gravity of manometer fluid (1.75 oil) Sp. Gr. ^Pressure head at CVS pump outlet PPO °Air temperature at CVS pump outlet (optional) PTO °Pump revolutions during test period N °Elapsed time for test period t in. Hg (kPa) °F (°C) °F (°C) in. H20 (kPa) in. H20 (kPa) °F (°C) in. Fluid (kPa) in. Fluid (kPa) °F (°C) Revs +.01 in. Hg (+.034 kPa) +.5°F (+.28°C) +.1°F (+.056°C) +.05 in. H_0 (+.012 kPa) ~" Z +.005 in. H20 (+.001 kPa) +.5°F (+.28°C) +.05 in. Fluid (+0.22 kPa) +.05 in. Fluid (+.022 kPa) +.5°F (+.28°C) + .05 s (5) After the system has been connected as shown in Figure 6, set the variable restrictor in the wide open position and run the CVS pump for twenty minutes. Record the calibration data. (6) Reset the restrictor valve to a more restricted condition in an increment of pump inlet depression (about 4" H?0 (1.0 kPa) that will yield a minimum of six data points for the total calibration. Allow the system to stabilize for 3 minutes and repeat the data acquisition. (7) Data analysis: (i) The air flow rate, Qs, at each test point is calculated in standard cubic feet per minute from the flowmeter data using the manufacturer's prescribed method. (ii) The air flow rate is then converted to pump flow, V , in cubic feet per revolution at absolute pump inlet temperature and pressure. -16- ------- VARIABLE FLOW RESTRICTOR TEMPERATURE INDICATOR ETI SURGE CONTROL VALVE MANOMETER Figure — PDP-CVS CALIBRATION CONFIGURATION ------- = 2ix _£x 29.92 o " n 528 P P Where: 3 3 V = Pump flow, ft / revolution (m /revolution) at T , P o P P Qs = Meter air flow rate in standard cubic feet per minute, standard conditions are 68°F, 29.92 in. Hg (20°C, 101.3 kPa). n = Pump speed in revolutons per minute. T = Pump inlet temperature, R(K) p = PTI + 460 for SI units, T = PTI + 273 P P = Absolute pump inlet pressure, in. Hg (kPa) P = P - PPI (SP.GR./13.57) for SI units, P = P - PPI p B Where: P = barometric pressure, in. Hg (kPa) B PPI = Pump inlet depression, in. fluid (kPa) SP. GR. = Specific gravity of manometer fluid relative to water. (iii) The correlation function at each test point is then calculated from the calibration data: Where: X = correlation function. o AP = The pressure differential from pump inlet to pump P outlet, in. Hg (kPa) = P - P e p P = Absolute pump outlet pressure, in. Hg (kPa) 8 = P + PPO (SP. GR./13.57) for SI units, P = P_ + PPO e D Where: PPO = Pressure head at pump outlet, in. fluid (kPa) -17- ------- (iv) A linear least squares fit is performed to generate the calibration equations which have the forms: V = D - M(X ) 8 - A°- B(AP°) D , M, A, and B are the slope-intercept constants describing the lines. (8) A CVS system that has multiple speeds should be calibrated on each speed used. The calibration curves generated for the ranges will be approximately parallel and the intercept values, D , will increase as the pump flow range decreases. (9) If the calibration has been performed carefully, the calculated values from the equation will be within +0.50% of the measured value of V . Values of M will vary from one pump to another, but values of D for pumps of the same make, model, and range should agree within + 3% of each other. Particulate influx from use will cause the pump slip to decrease as reflected by lower values for M. Calibrations should be performed at pump start-up and after major maintenance to assure the stability of the pump slip rate. Analysis of mass injection data will also reflect pump slip stability. (b) CFV calibration. (1) Calibration of the Critical Flow Venturi (CFV) is based upon the flow equation for a critical venturi. Gas flow is a function of inlet pressure and temperature: Where: Q = Flow K = Calibration coefficient P = Absolute pressure T = Absolute temperature The calibration procedure described below establishes the value of the calibration coefficient at measured values of pressure, temperature and air flow. (1) The manufacturers recommended procedure shall be followed for calibrating electronic portions of the CFV. (2) Measurements necessary for flow calibration are as follows: -18- ------- CALIBRATION DATA MEASUREMENTS PARAMETER SYM UNITS TOLERANCES 0Barometric Pressure (corrected) °Air temperature, flowmeter °Pressure depression upstream of LFE °Pressure drop across LFE matrix °Air flow °CFV inlet depression °Temperature at venturi inlet T •y °Specific gravity of manometer B ETI EPI EDP in. Hg (kPa) °F (8C) in. H20 (kPa) in. H20 (kPa) f t/min. (m/min.) in. fluid (kPa) °F (°C) +.01 in. Hg (+.034 kPa) + .1°F (+.056°C) +.05 in. H20 (+.012 kPa) +.005 in. H.O (+.001 kPa) +.5% +.05 in. fluid (+.022 kPa) +.5°F (+.28°C) fluid (1.75 oil) Sp. Gr. (3) Set up equipment as shown in Figure 7 and check for leaks. Any leaks between the flow measuring device and the critical flow venturi will seriously affect the accuracy of the calibration. (4) Set the variable flow restrictor to the open position, start the blower and allow the system to stabilize. Record data from all instruments. (5) Vary the flow restrictor and make at least 8 readings across the critical flow range of the venturi. (6) Data analysis. The data recorded during the calibration are to be used in the following calculations: (i) The air flow rate, Qs, at each test point is calculated in standard cubic feet per minute from the flow meter data using the manufacturer's prescribed method. (ii) Calculate values of the calibration coefficient for each test point: K = v -19- ------- CVS DUCT SAMPLER DUCT SURGE CONTROL VALVE VARIABLE FLOW RESTRICTOR jgjgggB&gsfijL ^ ETI MANOMETER FIGURE 7 CFV-CVS CALIBRATION CONFIGURATION ------- Where: Q = Flow rate in standard cubic feet per minute, 8 standard conditions are 68°F, 29.92 in. Hg (20°C, 101.3 kPa). T = Temperature at venturi inlet, R(K). P = Pressure at venturi inlet, mm Hg (kPa) V = P - PPI (SP. GR./13.57). for SI units P = P_ - PPI v B Where: PPI = Venturi inlet pressure depression, in. fluid (kPa). SP. GR. = Specific gravity of manometer fluid, relative to water. (iii) Plot K as a function of venturi inlet pressure. For sonic flow K will have a relatively constant value. As pressure decreases (vacuum increases) the venturi becomes unchecked and K decreases. See Figure 8. (iv) For a minimum of 8 points in the critical region calculate an average K and the standard deviation. (v) If the standard deviation exceeds 0.3% of the average K take corrective action. v (c) CVS System Verification. The following "gravimetric" technique can be used to verify that the CVS and analytical instruments can accurately measure a mass of gas that has been injected into the system. (Verification can also be accomplished by constant flow metering using critical flow orfice devices.) (1) Obtain a small cylinder that has been charged with pure propane or carbon monoxide gas (caution—carbon monoxide is poison- ous) . (2) Determine a reference cylinder weight to the nearest 0.01 grams. (3) Operate the CVS in the normal manner and release a quantity of pure propane or carbon monoxide into the system during the sampling period (approximately 5 minutes). -20- ------- OPERATING RANGE Kv INLET DEPRESSION (WH2O) FIGURE 8 —SONIC FLOW CHOKING ------- (4) The calculations of section 138 are performed in the normal way except, in the case of propane. The.density of propane (17.30 g/ft /carbon atom (0.6109 kg/m /carbon atom)) is used in place of the density of exhaust hydrocarbons. In the case of carbon monoxide, the density of 32.97 g/ft (1.164 kg/m ) is used. (5) The gravimetric mass is subtracted from the CVS measured mass and then divided by the gravimetric mass to determine the percent accuracy of the system. (6) The cause for any discrepancy greater than +2% must be found and corrected. 118 Hydrocarbon analyzer calibration. The FID hydrocarbon analyzer shall receive the following initial and periodic calibration (The HFID shall be operated to a set point + 10°F (+ 5.5°C) between 300 and 390°F (149 and 199°C). ~ (a) Initial and periodic optimization of detector response. Prior to its introduction into service and annually thereafter the FID hydrocarbon analyzer shall be adjusted for optimum hydrocarbon response: (1) Follow the manufacturer's instructions for instrument startup and basic operating adjustment using the appropriate fuel and zero grade air. (2) Optimize on the most common operating range. Introduce into the analyzer, a propane in air mixture with a propane concentration equal to approximately 90% of the most common operating range. (3) Select an operating fuel flow rate that will give near maximum response and least variation in response with minor fuel flow variations. (4) To determine the optimum air flow, use the fuel flow setting determined above and vary air flow. (5) After the optimum flow rates have been determined, they are recorded for future reference. (b) Initial and periodic determination of oxygen effect. Prior to its introduction into service and at least annually thereafter the FID hydrocarbon analyzer shall be checked to determine the effect of oxygen in the sample upon instrument response: (1) Zero the analyzer on nitrogen (N~) zero gas; check the zero by using zero grade air; differences in zero reading of more than 2% will require corrective action. -21- ------- (2) The following blends of propane shall be used to determine the effect of oxygen (P2> in the sample. Propane in N- Propane in 9.5 to 10.5% 0-, balance N Propane in zero grade air The volume concentration of propane in the mixtures should be equal to approximately 90% of the most common operating range. The zero shall be checafter each mixture is measured. If the zero has changed, the measurement shall be repeated. (3) If the response to propane in air differs by more than 3% from the response to propane in the 10% 0-/90% N~ mixture, or differs by more than 5% from the response to propane in N.; corrective action will be required. (4) If the response to propane in N. differs by more than 2% from the response to propane in 10% 0^/90% N»; corrective action will be required. (c) Initial and periodic calibration. Prior to its introduction into service and monthly thereafter the FID hydrocarbon analyzer shall be calibrated on all normally used instrument ranges. Use the same flow rate as when analyzing samples. (1) Adjust analyzer to optimize performance. (2) Zero the hydrocarbon analyzer with zero grade air. (3) Calibrate on each normally used operating range with propane in air calibration gases having nominal concentrations of 50 and 100% of that range. 119 Carbon monoxide analyzer calibration. The NDIR carbon monoxide analyzer shall receive the following initial and periodic calibrations: (a) Initial and periodic interference check. Prior to its introduction into service and annually thereafter the NDIR carbon monoxide analyzer shall be checked for response to water vapor and (1) Follow the manufacturer's instructions for instrument startup and operation. Adjust the analyzer to optimize performance on the most sensitive range. -22- ------- (2) Zero the carbon monoxide analyzer with either zero grade air or zero grade nitrogen. (3) Bubble a mixture of 3% CCL in N_ through water at room temperature and record analyzer response. (4) An analyzer response of more than 1% of full scale for ranges above 300 ppm full scale or of more than 3 ppm on ranges below 300 ppm full scale will require corrective action. (Use of condition- ing columns is one form of corrective action which may be taken.) (b) Initial and periodic calibration. Prior to its introduction into service and monthly thereafter the NDIR carbon monoxide analyzer shall be calibrated. (1) Adjust the analyzer to optimize performance. (2) Zero the carbon monoxide analyzer with either zero grade air or zero grade nitrogen. (3) Calibrate on each normally used operating range with carbon monoxide in N_ calibration gases having nominal concentrations of 15, 30, 45, 60, 75 and 90% of that range. For each range calibrated, if the deviation from a least-squares best-fit straight line is 2% or less of the value at each data point, concentration values may be calculated by use of a single calibration factor for that range. If the deviation exceeds 2% at any point, the best-fit non-linear equa- tion which represents the data to within 2% of each test point shall be used to determine concentration. 120 Oxides of nitrogen analyzer calibration. The Chemiluminescent oxides of nitrogen analyzer shall receive the following initial and periodic calibration. (a) Prior to its introduction into service and weekly thereafter the chemiluminescent oxides of nitrogen analyzer shall be checked for NO- to NO converter efficiency. Figure 9 is a reference for the following steps: (1) Follow the manufacturer's instructions for instrument startup and operation. Adjust the analyzer to optimize performance. (2) Zero the oxides of nitrogen analyzer with zero grade air or zero grade nitrogen. (3) Connect the outlet of the NOx generator to the sample inlet of the oxides of nitrogen analyzer which has been set to the most common operating range. -23- ------- FLOW CONTROL SOLENOID VALVE O2 OR AIR SUPPLY D ] 1 5 V.A.C. J OZONATOR ANALYZER INLET CONNECTOR NO/N2 I L SUPPLY ' ' (SEE FIG. 3 l FOR SYMBOL LEGEND) Figure 9 —NOx CONVERTER EFFICIENCY DETECTOR ------- (4) Introduce into the NOx generator analyzer-system an NO in nitrogen (N_) mixture with a NO concentration equal to approximately 80% of the most common operating range. The NO- content of the gas mixture shall be less than 5% of the NO concentration. (5) With the oxides of nitrogen analyzer in the NO mode, record the concentration of NO indicated by the analyzer. (6) Turn on the NOx generator 0- (or air) supply and adjust the 0» (or air) flow rate so that the NO indicated by the analyzer is about 10% less than indicated in step 5. Record the concentration of NO in this NO + 0_ mixture. (7) Switch the NOx generator to the generation mode and adjust the generation rate so that the NO measured on the analyzer is 20% of that measured in step 5. There must be at least 10% unreacted NO at this point. Record the concentration of residual NO. (8) Switch the oxides of nitrogen analyzer to the NOx mode and measure total NOx. Record this value. (9) Switch off the NOx generation but maintain gas flow through the system. The oxides of nitrogen analyzer will indicate the NOx in the NO + 0_ mixture. Record this value. (10) Turn off the NOx generator 0- (or air) supply. The analyzer will now indicate the NOx in the original NO in N« mixture. This value should be no more than 5% above the value indicated in step 4. (11) Calculate the efficiency of the NOx converter by substituting the concentrations obtained into the following equation: % Eff . = 1 4- -- x 10° . = ( where a = concentration obtained in step 8 b = concentration obtained in step 9 c = concentration obtained in step 6 d = concentration obtained in step 7 If converter efficiency is not greater than 90% corrective action will be required. (b) Initial and periodic calibration. Prior to its introduction into service and monthly thereafter the chemiluminescent oxides of nitrogen analyzer shall be calibrated on all normally used instrument ranges. Use the same flow rate as when analyzing samples. Proceed as follows: -24- ------- (1) Adjust analyzer to optimize performance. (2) Zero the oxides of nitrogen analyzer with zero grade air or zero grade nitrogen. : (3) Calibrate on each normally used operating range with NO in N9 calibration gases with nominal concentrations of 50 and 100% of tfiat range. 121 Carbon dioxide analyzer calibration. Prior to its introduction into service and monthly thereafter the NDIR carbon dioxide analyzer shall be calibrated: (a) Follow the manufacturer's instructions for instrument startup and operation. Adjust the analyzer to optimize performance. (b) Zero the carbon dioxide analyzer with either zero grade air or zero grade nitrogen. (c) Calibrate on each normally used operating range with carbon dioxide in N» calibration gases with nominal concentrations of 15, 30, 45, 60, 75 and 90% of that range. For each range calibrated, if the deviation from a least-squares best-fit straight line is 2% or less of the value at each data point, concentration values may be calculated by use of a single calibration factor for that range. If the deviation exceeds 2% at any point, the best-fit non-linear equation which repre- sents the data to within 2% of each test point shall be used to deter- mine concentration. 122 Calibration of other equipment. Other test equipment used for testing shall be calibrated as often as required by the manufacturer or as necessary according to good practice. 123 Test procedures, overview. (a) The overall test consists of prescribed sequences of fueling, parking and operating conditions. Vehicles are either tested for only exhaust emissions or are tested for exhaust and evaporative emissions. The evaporative portion of the test procedure occurs before and after the exhaust emission test, and, in some cases, during the exhaust emission test. (b) The exhaust emission test is designed to determine hydro- carbon, carbon monoxide, and oxides of nitrogen mass emissions while simulating an average trip in an urban area of 7.5 miles (12.1 km). The test consists of engine startups and vehicle operation on a chassis dynamometer, through a specified driving schedule. A proportional part of the diluted exhaust emissions is collected continuously for subsequent -25- ------- analysis, using a constant volume (variable dilution) sampler. (Diesel dilute exhaust is continuously analyzed for hydrocarbons using a heated sample line and analyzer). (c) The evaporative emission test (gasoline fueled vehicles only) is designed to determine hydrocarbon evaporative emissions as a consequence of diurnal temperature fluctuation, urban driving, and hot soaks during parking. It is associated with a series of events repre- sentative of a motor vehicle's operation, which result in hydrocarbon vapor losses. The test procedure is designed to measure: (1) Diurnal breathing losses resulting from daily temperature changes, measured by the enclosure technique; (2) Running losses from suspected sources (if indicated by engineering analysis or vehicle inspection) resulting from a simulated trip on a chassis dynamometer, measured by carbon traps; and (3) Hot soak losses which result when the vehicle is parked and the hot engine is turned off, measured by the enclosure technique. (d) Except in cases of component malfunction or failure, all emission control systems installed on or incorporated in a motor vehicle shall be functioning during all procedures in this section. 124 Transmissions. (a) All test conditions shall be run with automatic and automatic stick shift transmissions in "Drive" (highest gear); manual transmis- sions shall be run in highest gear, except as noted. Automatic stick- shift transmissions may be shifted as manual transmissions if specified by the manufacturer. (b) Cars equipped with free-wheeling or overdrive units shall be tested with these units locked out of operation. (c) Idle modes shall be run with automatic transmissions in "Drive" and the wheels braked, manual transmissions shall be in gear with the clutch disengaged; except first idle, see sections 132 and 133. (d) The vehicle shall be driven with minimum accelerator pedal movement to maintain the desired speed. (e) Acceleration modes shall be driven smoothly. Automatic transmissions shall shift automatically through the normal sequence of gears; manual transmissions shall be shifted as recommended by the manufacturer with the operator releasing the accelerator pedal during each shift and accomplishing the shift with minimum time. If the vehicle cannot accelerate at the specified rate, the vehicle shall be -26- ------- operated with the accelerator pedal fully depressed until the vehicle speed reaches the value prescribed for that time in the driving schedule. (f) The deceleration modes shall be run in gear using brakes or accelerator pedal as necessary to maintain the desired speed. Manual transmission vehicles shall have the clutch engaged and shall not change gears from the previous mode. For those modes which decelerate to zero, manual transmission clutches shall be depressed when the speed drops below 15 mph (24 kph), when engine roughness is evident, or when engine stalling is imminent. (g) Manual transmissions will be down shifted at the beginning of or during a power mode if recommended by the manufacturer or if the engine obviously is lugging. (h) If shift speeds are not recommended by the manufacturer, manual transmission vehicles shall be shifted from first to second gear at 15 mph (24 kph), from second to third gear at 25 mph (40 kph), and, if so equipped, from third to fourth gear at 40 mph (64 kph). Fifth gear, if so equipped, may be used at the manufacturers option. (i) If a four- or five- speed manual transmission has a first gear ratio in excess of 5:1, follow the procedure for three- or four- speed vehicles as if the first gear did not exist. 125 Road load power and inertia weight determination. (a) Flywheels, electrical or other means of simulating inertia as shown in the following table shall be used. If the equivalent inertia specified is not available on the dynamometer being used, the next higher equivalent inertia (not to exceed 250 Ibs) available shall be used. Loaded vehicle weight (pounds) Up to 1,125 T 1 9ft f n 1 17S - ^ ^7fi t-« ^ fi")ci i f.'jf. *-n 1 875 1 Q7fi f-n O IOC 9 i jc. 4-0 o •37';_ _ ? "376 fr> 9 fi?5 - - 2 626 f-n 2 875 2 876 t-n "} 250 •} 251 f-n "} 75(1 1 751 t-n L 250 A OS! «-n /. -jK.n A 751 t-n 5 250 S 2 SI f-n S 7 SO Equivalent Road load inertia power at weight 50 mph (pounds) (horsepower) 1,000 1,250 1,500 1,750 2,000 2,250 2,500 2,750 3,000 3,500 4,000 4,500 5,000 5,500 s snn 5.9 6.5 7.1 7.7 8.3 8.8 9.4 £.9 10.3 11.2 12.0 12.7 13.4 13.9 1 A. L -27- ------- (b) Power absorption unit adjustment. (1) The power absorption unit shall be adjusted to reproduce road load power at 50 mph true speed. The indicated road load power setting shall take into account the dynamometer friction. The relation- ship between road load (absorbed) power and indicated road load power for a particular dynamometer shall be determined by the procedure outlined in section 116 or other suitable means. (2) The road load power listed in the table above shall be used or the vehicle manufacturer may determine the road load power by an alternate procedure or the vehicle manufacturer may determine the road load power by the following procedure and request its use: (i) Gasoline fueled vehicles. (A) Measuring the absolute manifold pressure of a representative vehicle, of the same equivalent inertia weight class, when operated on a level road under balanced wind conditions at a true speed of 50 mph (80 kph), and (B) Noting the dynamometer indicated road load horsepower setting required to reproduce that manifold pressure when the same vehicle is operated on the dynamometer at a true speed of 50 mph. The tests on the road and on the dynamometer shall be performed with the same vehicle ambient absolute pressure (usually barometric), i.e., within +5 mm Hg (+0.7 kPa). (C) The road load power shall be determined according to the procedure outlined in section 116 and adjusted according to the following if applicable. (ii) Diesel vehicles. (A) Measuring the fuel flow rate of a representative vehicle of the same equivalent inertia weight class, when operated on a level road under balanced wind conditions at a true speed of 50 mph, and (B) Noting the dynamometer indicated road load horsepower setting required to reproduce that fuel flow rate when the same vehicle is operated on the dynamometer at a true speed of 50 mph (80 kph). The tests on the road and on the dynamometer shall be performed with the same vehicle ambient absolute pressure (usually barometric), i.e. within +5 mm Hg (+0.7 kPa). (C) The road load power shall be determined according to the procedure outlined in section 116 and adjusted according to the following if applicable. -28- ------- 126 Test,sequence, general requirements. The test sequence shown in Figure 10 shows the steps encountered as the test vehicle undergoes the procedures subsequently described to determine conformity with the standards set forth. Ambient temperature levels encountered by the test vehicle throughout the test sequence shall not be less than 68°F.. (20°C) nor more than 86°F (3Q8C). The vehicle shall be approximately level during all phases of the test sequence to prevent abnormal fuel distribution. 127 Vehicle preparation. (a) For gasoline fueled vehicles prepare the fuel tank(s) for recording the temperature of the prescribed test fuel at the approximate mid volume of the fuel. (b) Provide additional fittings and adapters, as required, to accommodate a fuel drain at the lowest point possible in the tank(s) as installed on the vehicle. 128 Vehicle preconditioning. *. (a) The vehicle shall be moved to the test area and the following operations performed: (1) The fuel tank(s) shall be drained through the provided - fueled tank(s) drain(s) and filled in the normal fashion to contain approximately 2 gallons (7.57 liters) of the specified test fuel, section 111 (for diesel powered vehicles the tank shall be filled to the prescribed "tank fuel volume". When additional preconditioning, as described in (a)(3) is to be performed, additional fuel may be added up to the prescribed "tank fuel volume". For the above operations the evaporative emission control system shall neither be abnormally purged nor abnormally loaded. NOTE: "Tank fuel volume" means the volume of fuel in the fuel tank prescribed to be 40% of nominal tank capacity rounded to the nearest tenth of U.S. gallon. (2) Within one hour of being fueled the vehicle shall be placed, either by being driven or pushed, on a dynamometer and operated through one Urban Dynamometer Driving Schedule test procedure, see section 113 and Appendix I of the Federal Register. A gasoline fueled test vehicle may not be used to set dynamometer horsepower. (3) For those unusual circumstances where additional precondi- tioning is desired to insure that the evaporative emission control system is stabilized, such preconditioning shall consist of an initial one hour minimum soak and, one, two or three driving cycles of the. UDDS, as described in (a)(2), each followed by a soak of at least one -29- ------- DYNO PRECONDITIONING «HEAT FUKL-1 HOUR •60-84°F DIURNAL ENCLOSURE TEST 1 HOUR MAX. 5 MIN. MAX. 12-36 HOURS (no max. for diesels) 0-1 HOUR *~1 COLD START EXHAUST TEST g EVAP TEST NOT PERFORMED HC RUNNING 1 LOSSES-AS REQ | 1 HOT START EXHAUST TEST HOT SOAK ENCLOSURE TEST 10-MIN. 5 MIN. MAX. Figure 10 TEST SEQUENCE ------- hour with engine off, engine compartment cover closed and cooling fan off. The vehicle may be driven off the dynamometer following each UDDS for the soak period. (b) Within five minutes of completion of preconditioning the vehicle shall be driven off the dynamometer and parked. The vehicle shall be stored for not less than 12 hours nor for more than 36 hours (except diesel fueled vehicles which have no maximum time limitation) prior to the cold start exhaust test. (Gasoline fueled vehicles undergo a one hour diurnal heat build prior to the cold start exhaust test. A wait of up to one hour is permitted between the end of the diurnal heat build and the beginning of the cold start exhaust test. See section 126 and Figure 10.) (c) Vehicles to be tested for evaporative emissions shall be processed in accordance with procedures in sections 129 through 134. Vehicles to be tested for exhaust emissions only shall be processed according to sections 129 through 133. 129 Diurnal breathing loss test. (a)(1) Following vehicle preparation and vehicle preconditioning procedures described in section 127 and section 128, the test vehicle shall be allowed to soak for a period of not less than 12 or more than 36 hours prior to the exhaust emission test. The diurnal test shall take place not less than 10 or more than 35 hours after the end of the preconditioning procedure. The start of the exhaust test shall follow the end of the diurnal test within one hour. (2) Gasoline fueled vehicles to be tested for exhaust emissions only, shall undergo the diurnal heat build. Since no evaporative measurements are necessary, an evaporative enclosure is not required. (b) The evaporative emission enclosure shall be purged for several minutes immediately prior to the test. NOTE: If at anytime the hydrocarbon concentration exceeds 15,000 ppm C the enclosure should be immediately purged. This concentration provides a 4:1 safety factor against the lean flammability limit. (c) The FID hydrocarbon analyzer shall be zeroed and spanned immediately prior to the test. (d) If not already on, the evaporative enclosure mixing fan shall be turned on at this time. (e) Immediately prior to the diurnal breathing loss test, the fuel tank(s) of the prepared vehicle shall be drained and recharged with the specified test fuel, section 111, to the prescribed "tank, fuel volume". The temperature of the fuel prior to its delivery to the fuel tank shall be between 50 and 60°F (10 and 16°C). -30- ------- (f) The test vehicle, with the engine shut off, shall be moved into the evaporative emission enclosure,.the test vehicle windows and luggage compartments shall be opened, the fuel tank temperature sensor shall be connected to the temperature recording system, and, if required, the heat source shall be properly positioned with respect to the fuel tank(s) and/or connected to the temperature controller. (g) The enclosure doors shall be closed and sealed. (h) The temperature recording system shall be started. (i) When the fuel temperature recording system reaches 60 + 1°F (16+0.5°C), immediately: (1) Analyze enclosure atmosphere for hydrocarbons and record. This is the initial (time = 0 minutes) hydrocarbon concentration,' C r., section 137. : ; (2) Start diurnal heat build and record time. This commences the 60+2 minute test period. (j) The fuel shall be heated in such a way that its temperature change conforms to the following function to within + 2°F (+ 1.1°C): F = 60 + 0.4t for SI units, C = 15.556 + 2/9t Where: F = fuel temperature, °F C = fuel temperature, °C t = time since beginning of test, minutes. After 60+2 minutes of heating, the fuel temperature shall be 84 + 1°F (29 +~0.5°C). (k) The FID hydrocarbon analyzer shall be zeroed and spanned immediately prior to the end of the diurnal test. (1) The end of the diurnal breathing loss test occurs 60+2 minutes after the heat build begins, subparagraph (i)(2). Analyze the enclosure atmosphere for hydrocarbons and record. This is the final (time = 60 minutes) hydrocarbon concentration, C f, section 137. The time (or elapsed time) of this analysis shall be recorded. (m) The heat source shall be turned off and the enclosure doors unsealed and opened. (n) The heat source shall be moved away from the vehicle, if required, and/or disconnected from the temperature controller, the fuel tank temperature sensor shall be disconnected from the temperature recording system, the test vehicle windows and luggage compartments may be closed and the test vehicle, with the engine shut off, shall be removed from the evaporative emission enclosure. -31- ------- 130 Running loss test. (a) If an engineering analysis or vehicle inspection indicate the possibility of evaporative emissions during vehicle operation, evaporative emission running loss measurements shall be made during the cold transient and stabilized portion of the exhaust emission test. Since running loss measurements cannot be made in the enclosure, the equipment described in the Federal Register shall be used to collect these emissions. (1) The procedure in section 131 shall be followed. (2) Prior to the initiation of the cold start exhaust emission test, the vapor loss measurement system shall be connected to all suspected sources of running loss evaporative emissions. (3) The cold start transient and stabilized exhaust emission test portions shall be conducted according to the procedures of section 131 through section 133. (4) Within one minute after the end of the stabilized exhaust emission test, the vapor loss measurement system shall be disconnected from the vehicle and the inlets and outlets sealed. (5) Within one hour from the end of the running loss measurement, weigh the vapor collection traps. 131 Dynamometer procedure. (a) The dynamometer run consists of two tests, a "cold" start test after a minimum 12-hour and a maximum 36 hour soak according to the provisions of section 128 and section 129 and a "hot" start test following the "cold" start by 10 minutes. Engine startup (with all accessories turned off), operation over the driving schedule, and engine shutdown make a complete cold start test. Engine startup and operation over the first 505 seconds of the driving schedule complete the hot start test. The exhaust emissions are diluted with ambient air and a continuously proportional sample is collected for analysis during each phase. The composite samples collected in bags are analyzed for hydrocarbons (except diesel hydrocarbons which are analyzed contin- uously) , carbon monoxide, carbon dioxide, and oxides of nitrogen. A parallel sample of the dilution air is similarly analyzed for hydrocarbon, carbon monoxide, and oxides of nitrogen. (b) During dynamometer operation, a fixed speed cooling fan shall be positioned so as to direct cooling air to the vehicle in an appropriate manner with the engine compartment cover open. In the case of vehicles with front engine compartments, the fan shall be squarely positioned within 12 inches of the vehicle. In the ease of vehicles with rear engine compartments (or if special designs make the above impractical), the cooling fan shall be placed in a position to -32- ------- provide sufficient air to maintain vehicle cooling. The fan capacity shall normally not exceed 5,300 cfm (2.50 m /s). If, however, the manufacturer can show that during field operation the vehicle receives additional cooling, and that such additional cooling is needed to provide a representative test, the fan capacity may be increased or additional fans used. (c) The vehicle speed as measured from the dynamometer rolls shall be used. -- (d) Practice runs over the prescribed driving schedule may be performed for the purpose of finding the minimum throttle action to maintain the proper speed-time relationship, or to permit sampling system adjustments. NOTE: When using two-roll dynamometers a truer speed-time trace may be obtained by minimizing the rocking of the vehicle in the rolls. The rocking of the vehicle changes the tire rolling radius on each roll. This rocking may be minimized by restraining the vehicle horizontally (or nearly so) by using a cable and winch. (e) The drive wheel tires may be inflated up to 45 psig (310 kPag) in order to prevent tire damage. The drive wheel tire pressure shall be reported with the test results. (f) If the dynamometer has not been operated during the 2 hour period immediately preceding the test it shall be warmed up for 15 minutes by operating at 30 raph (48 kph) using a non-test vehicle or as recommended by the dynamometer manufacturer. (g) If the dynamometer horsepower must be adjusted manually, it shall be set within 1 hour prior to the exhaust emissions test phase. The test vehicle shall not be used to make this adjustment. Dynamometers using automatic control of preselectable power settings may be set anytime prior to the beginning of the emissions test. 132 Engine starting and restarting. (a) Gasoline fueled vehicles. Paragraph (a) applies to gasoline fueled vehicles. (1) The engine shall be started according to the manufacturer's recommended starting procedures. The initial 20 second idle period shall begin when the engine starts. (2) Choke operation: (i) Vehicles equipped with automatic chokes shall be operated according to the instructions in the manufacturer's operating instructions or owner's manual including choke setting and "kick-down" from cold fast idle. The transmission shall be placed in gear 15 seconds after the engine is started. If necessary, braking may be employed to keep the drive wheels from turning. -33- ------- (ii) Vehicles equipped with manual chokes shall be operated according to the manufacturer's operating instructions or owners manual. (3) The operator may use the choke, accelerator pedal, etc. where necessary to keep the engine running. (4) If the manufacturer's operating instructions or owner's manual does not specify a warm engine starting procedure, the engine (automatic and manual choke engines) shall be started by depressing the accelerator pedal about half way and cranking the engine until it starts. (b) Diesel fueled vehicles. The engine shall be started according ^to. the manufacturer's recommended starting procedures. The initial 2O-second-idle period shall begin when the engine starts. The trans- mission shall be placed in gear 15 seconds after the engine is started. If necessary, braking may be employed to keep the drive wheels from turning. (c) If the vehicle does not start after 10 seconds of cranking, cranking shall cease and the reason for failure to start shall be determined. The gas flow measuring device (or revolution counter) on the constant volume sampler (and the hydrocarbon integrator when testing diesel vehicles, see section 133, Dynamometer test runs) shall be turned off and the sample selector valves placed in the "standby" position during this diagnostic period. In addition, either the CVS should be turned off or the exhaust tube disconnected from the tail- pipe during the diagnostic period. (1) If failure to start is an operational error, the vehicle shall be rescheduled for testing from a cold start. If failure to start is caused by vehicle malfunction, corrective action of less than 30 minutes duration may be taken and the test continued. The sampling system shall be reactivated at the same time cranking is started. When the engine starts, the driving schedule timing sequence shall begin. If failure to start is caused by vehicle malfunction and the vehicle cannot be started, the test shall be voided, the vehicle removed from the dynamometer, corrective action taken, and the vehicle rescheduled for test. (d) If the engine "false starts", the operator shall repeat the recommended starting procedure (such as resetting the choke, etc.) (e) Stalling: (1) If the engine stalls during an idle period, the engine shall be restarted immediately and the test continued. If the engine cannot be started soon enough to allow the vehicle to follow the next accelera- tion as prescribed, the driving schedule indicator shall be stopped. When the vehicle restarts, the driving schedule indicator shall be reactivated. -34- ------- (2) If the engine stalls during soine operating mode other than idle, the driving schedule indicator shall be stopped, the vehicle shall then be restarted and accelerated to the speed required at that point in the driving schedule and the test continued. During acceleration to this point, shifting shall be performed in accordance with section 124. (3) If the vehicle will not restart within 1 minute, the test shall be voided, the vehicle removed from the dynamometer, corrective action taken, and the vehicle rescheduled for test. 133 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 or more than 36' hours before the cold start exhaust emission test. The cold start exhaust test shall follow the diurnal breathing loss test by^not more than 1 hour. The vehicle shall be stored prior to the emission test;. 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 (12.1 km) and simulates a hot start drive of 7.5 miles (12.1 km). 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 period, representing the hot start "transient" phase, terminates at the same point in the driving schedule as the first period 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. (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 position the cooling fan. (3) With the sample selector valves in the "standby" position connect evacuated sample collection bags to the two dilute exhaust and two dilution air sample collection systems. (4) Start the Constant Volume Sampler (if not already on), the sample pumps, the temperature recorder, the vehicle cooling fan and the heated hydrocarbon analysis recorder (diesel only). (The heat -35- ------- exchanger of the constant volume sampler, if used, diesel hydrocarbon analyzer continuous sample line and filter (if applicable) should be preheated to their respective operating temperatures before the test begins.) (5) Adjust the sample flow rates to the desired flow rate (minimum of 10 cfh, 0.28 m /hr) and set the gas flow measuring devices to zero. NOTE: CFV-CVS sample flowrate is fixed by the venturi design. (6) Attach the flexible exhaust tube to the vehicle tailpipe(s). (7) Start the gas flow measuring device, position the sample selector valves to direct the sample flow into the "transient" exhaust sample bag and the "transient" dilution air sample bag, (turn on the diesel hydrocarbon analyzer system integrator and mark the recorder chart, if applicable) 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, section 113. (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 gas flow measuring device No. 1 (and the diesel hydrocarbon integrator No. 1, mark the diesel hydrocarbon recorder chart) and start gas flow measuring device No. 2 (and diesel hydrocarbon integrator No. 2). As soon as possible, and in no case longer than 20 minutes after the end of this portion of the test, transfer the "transient" exhaust and dilution air sample bags, to the analytical system and process the samples according to section 135. ; (12) Turn the engine off 2 seconds after the end of-the last deceleration (at 1,369 seconds). (13) Five seconds after the engine stops running, simultaneously turn off gas flow measuring device No. 2 (and the diesel hydrocarbon integrator No. 2, mark the hydrocarbon recorder chart, if applicable) and position the sample selector valves to the "standby" position. As soon as possible, and in no case longer than 20 minutes after the end of this portion of the test, transfer the "stabilized" exhaust and dilution air sample bags, to the analytical system and process the samples according to section 135. (14) Immediately after the end of the sample period turn off the cooling fan and close the engine compartment cover. -36- ------- (15) Turn off the CVS or disconnect the exhaust tube.from the tailpipe of the vehicle. (16) Repeat the steps in paragraph (b) (2) through (10) of this section 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 paragraph (b) (7) of this section shall begin between 9 and 11 minutes after the end of the sample period for the cold start test. (17) At the end of the deceleration which is scheduled to occur at 505 seconds, simultaneously turn off gas flow measuring device No. 1 (and diesel hydrocarbon integrator No. 1, mark the diesel hydrocarbon recorder chart, if applicable) and position the sample selector valve to the "standby" position. (Engine shutdown is not part of the hot start test sample period.) (18) As soon as possible, and in no case longer than 20 minutes after the end of this portion of the test transfer the hot start "transient" exhaust and dilution air sample bags, to the analytical system and process the samples according to section 135. (19) Disconnect the exhaust tube from the vehicle tailpipe(s) and drive vehicle from dynamometer. (20) The constant volume sampler may be turned off, if desired. (21) Vehicles to be tested for evaporative emissions will proceed according to section 134. For all others this completes the test sequence. 134 Hot soak test. The hot soak evaporative emission test shall be conducted im- mediately following the hot transient exhaust emission test. . (a) Prior to the completion of the hot start transient exhaust emission sampling period, the evaporative emission enclosure shall be purged for several minutes. (b) The FID hydrocarbon analyzer shall be zeroed and spanned immediately prior to the test. (c) If not already on, the evaporative enclosure mixing fan shall be turned on at this time. (d) Upon completion of the hot transient exhaust emission sampling period, the vehicle engine compartment cover shall be closed, the cooling fan shall be moved, the vehicle shall be disconnected from the dynamometer and exhaust sampling system and then driven at minimum throttle to within 10 feet (3.3 m) of the vehicle entrance to the enclosure. -37- ------- (e) The test vehicle windows and luggage compartments shall be opened. (f) The temperature recording system shall be started. (g) The vehicle's engine shall be shutoff and the vehicle shall be pushed into the enclosure. The time" of engine shutoff shall be noted on the evaporative emission hydrocarbon data recording system. (h) The enclosure doors shall be closed and sealed within one minute of engine shutdown and within five minutes after the end of the exhaust test. (i) The 60+0.5 minute hot soak begins when the enclosure doors are sealed. The enclosure atmosphere shall be analyzed and recorded. This is the initial (time = 0 minutes) hydrocarbon concentration, C.,.,., for use in calculating evaporative losses, see section 137. nCl (j) The test vehicle shall be permitted to soak for a period..of at least one hour in the enclosure. (k) The FID hydrocarbon analyzer shall be zeroed and spanned immediately prior to the end of the test. (1) At the end of the 60 + 0.5 minute test period, again analyze the enclosure atmosphere and record time. This is the final (time = 60 minutes) hydrocarbon concentration, C rf, for use in calculating evaporative losses, see section 137. This operation completes the evaporative emission measurement procedure. 135 Exhaust sample analysis. The following sequence of operations shall be performed in conjunction with each series of measurements: (a) Zero the analyzers and obtain a stable zero reading. Recheck after tests. (b) Introduce span gases and set instrument gains. In order to avoid corrections, span and calibrate at the same flow rates used to analyze the test sample. Span gases should have concentrations equal to approximately 80 percent of full scale. If gain has shifted signifi- cantly on the analyzers, check the calibrations. Show actual concentra- tions on chart. (c) Check zeros; repeat the procedure in paragraphs (a) and (b) of this section if required. (d) Check flowrates and pressures. (e) Measure HC, CO, C0_ and NOx concentrations of samples. -38- ------- (f) For diesel vehicles, continuously record (integrate electron- ically if desired) dilute hydrocarbon emission levels during test. Background samples are collected in sample bags and analyzed as above. (g) Check zero and span points. If difference is greater than 2% of full scale, repeat the procedure in paragraphs (a) through (f). 136 Records required. 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 - Evap. family - Idle rpm - Fuel system (fuel injection, nominal fuel tank(s) capacity, fuel tank(s) location, number of carburetors, number of carburetor barrels) - Inertia loading - Actual curb weight recorded at 0 miles - Actual road load at 50 mph (80 kph) and drive wheel tire pressure, as applicable. (g) Indicated road load power absorption at 50 mph (80 kph) and dynamometer serial number. As an alternative to recording the dynamometer serial number, a reference to a vehicle test cell number may be used, provided the test cell records show the pertinent information. (h) All pertinent instrument information such as tuning - gain - serial number - detector number - range. As an alternative, a reference to a vehicle test cell number may be used, provided test cell calibration records show the pertinent instrument information. (i) Recorder charts: Identify zero, span, exhaust gas, and dilution air sample traces. (j) Test cell barometric pressure, ambient temperature and humidity. NOTE: A central laboratory barometer may be used; provided that individual test cell barometric pressures are shown to be within +0.1 percent of the barometric pressure at the central barometer location. (k) Fuel temperatures, as prescribed. -39- ------- (1) Pressure of the mixture of exhaust and dilution air entering the CVS metering device, the pressure increase across the device, and the temperature at the inlet. The temperature may be recorded con- tinuously or digitally to determine temperature variations. (m) The number of revolutions of the positive displacement pump accumulated during each test phase while exhaust samples are being collected. The number of standard cubic feet metered by a critical flow venturi during each test phase would be the equivalent record for a CFV-CVS. (n) The humidity of the dilution air. NOTE: If conditioning columns are not used (see section 119 and section 138) this measurement can be deleted. If the conditioning columns are used and the dilution air is taken from the test cell, the ambient humidity can be used for this measurement. (o) Temperature set point of the heated sample line and heated hydrocarbon detector temperature control system (for diesel vehicles only). 137 Calculations; evaporative emissions. The calculation of the net hydrocarbon mass change in the enclosure is used to determine the diurnal and hot soak mass emissions. The mass is calculated from initial and final hydrocarbon concentrations in ppm carbon, initial and final enclosure ambient temperatures, initial and final barometric pressures, and net enclosure volume using the following equation: = k V x 10 n -4 CHCf Bf CHCi PBi Tf T. Where: = hydrocarbon mass, g. C = hydrocarbon concentration as ppm carbon. 3 3 V = net enclosure volume, ft fm ) as determined by subtracting 50 ft (1.42 m ) (volume of vehicle with trunk and windows open) from the enclosure volume. PB = barometric pressure, in. Hg (kPa). T = enclosure ambient temperature, R (K). -40- ------- k = .208 (12 + H/C) for SI units, k = 1.2 (12 + H/C). Where: H/C = Hydrogen-carbon ratio. H/C =2.33 for diurnal emissions. H/C =2.2 for hot soak emissions. i = indicates initial reading. f = indicates final reading. 138 Calculations; exhaust emissions. The final reported test results shall be computed by use of the following formula: (a) For light duty vehicles and light duty trucks: Y = (0.43 Y + 0.57 Y, + Y )/7.5 wm ct nt s Where: Y = Weighted mass emissions of each pollutant, i.e., HC, CO, or NOx, in grams per vehicle mile. Y =* Mass emissions as calculated from the "transient" ct phase of the cold start test, in grams per test phase. Y =•= Mass emissions as calculated from the "transient" phase of the hot start test, in grams per test phase. Y = Mass emissions as calculated from the "stabilized" phase of the cold start test, in grams per test phase. (b) The mass of each pollutant for each phase of both the cold start test and the hot start test is determined from the following: (1) Hydrocarbon mass: HC * V . X Density.,., X (HC /1,000,000) mass mix 7HC cone ' -41- ------- (2) Oxides of nitrogen mass: N0xmass = Vmix X DenSlty N02 X ^ X (N°Xconc / (3) Carbon monoxide mass: CO - V , ' X Density.,^ X (O) 71,000,000) mass mix CO cone (4) Carbon dioxide mass: C00 - V . X Density.. X (CO. /100) 2mass mix •'CO- 2conc (c) Meaning of symbols: (1) HC - Hydrocarbon emissions, in grams per test , mass phase. 3 DensityHf, =»Density of hydrocarbons is 16.33 g/ft (.5767 kg/m ), assuming an average carbon to hydrogen ratio of 1:1.85, at 68°F (20°C) and 760 mm Hg (101.3 kPa) pressure. HC » Hydrocarbon concentration of the dilute ex haust sample corrected for background, in ppm carbon equivalent, i.e., equivalent propane X 3. Where: HCconc ' HCe - HCd HC == Hydrocarbon concentration of the dilute exhaust sample or, for diesel, average hydrocarbon concentration of the dilute exhaust sample as calculated from the integrated HC traces, in ppm carbon equivalent. HC, » Hydrocarbon concentration of the dilution air as measured, in ppm carbon equivalent. (2) N^x - Oxides of nitrogen emissions, in grams per test phase. Density =•= Density of oxides of nitrogen is 54.16 3 2 3 g/ft (1.913 kg/m ), assuming they are in the form of nitrogen dioxide, at 68°F (20°C) and 760 mm Hg (101.3 kPa) pressure. NOx » Oxides of nitrogen concentration of the dilute exhaust sample corrected for background, in ppm. NOx = NOx - NOx, (1-1/DF) cone e d -42- ------- Where: NOx - Oxides of nitrogen concentration of the dilute exhaust sample as measured, in ppm. NOx, * Oxides of nitrogen concentration of the dilute air as measured, in ppm. (3) CO » Carbon monoxide emissions, in grams per test mass phase. 3 Densityro ^-Density of carbon monoxide is 32.97 g/ft (1.164 Kg/in ), at 68°F (20°C) and 760 mm Hg (101.3 kPa) pressure. CO = Carbon monoxide concentration of the dilute £OC1C exhaust sample corrected for background, water vapor, and CO- extraction, in ppm. Where: Where: Where: CO cone C°e ~ C°d CO = Carbon monoxide concentration of the dilute exnaust sample volume corrected for water vapor and carbon dioxide extraction, in ppm. The calculation assumes the carbon to hydrogen ratio of the fuel is 1:1.85. CO (1-0.01925 CO- - 0.000323 R) CO 2e em CO =* Carbon monoxide concentration of the dilute fm aust sample as measured, in ppm. CO- » Carbon dioxide concentration of the dilute exnaust sample, in percent. R = Relative humidity of the dilution air, in per cent (see section 136. CO, - Carbon monoxide concentration of the dilution air corrected for water vapor extraction, in ppm. CO, = (1-0.000323 R) CO, d dm CO, = Carbon monoxide concentration of the dilution air sample as measured, in ppm. -43- ------- NOTE: If a CO instrument which meets the criteria specified in section 110 is used and the conditioning column has been deleted, CO can be substituted directly for CO and C0dm can be substituted directly for CO.. (4) C0_ * Carbon dioxide emissions, in grams per test v ' , 2mass phase. 3 DensityCO- 5 Density of carbon dioxide is 51.85 g/ft (1.843 kg/m ), at 68°F (20°C) and 760 mm Hg (101.3 kPa) pressure. CO- = Carbon dioxide concentration of the dilute i f* on c* exhaust sample corrected for background, in percent. C°2conc •' C°2e ' C°2d Where: CO • = Carbon dioxide concentration of the dilution air as measured, in percent. (5) DF = 13.4/[CO. + (HC + CO ) 10~4] /e e e K^ .=* Humidity correction factor. Kg - 1/[1-0.0047 (H-75)] for SI units - 1/[1-0.033 (H-10.7)] Where: H = Absolute humidity in grains (grams) of water per pound (kilogram) of dry air. H - [(43.478) R X P,]/[P_ - (P. X R /100)] a a B da for SI units, H - [(6.0266) R X P. ]/[?.. - (P, X R /100) ] 3, Q. jj Cl 3. RE = Relative humidity of the ambient air, in percent. P. » Saturated vapor pressure, in mm Hg (kPa) at the ambient dry bulb temperature. PB = Barometric pressure, in mm Hg (kPa). V . = Total dilute exhaust volume in cubic feet per test phase correctd to standard conditions (528 R (293 K) and 760 mm Hg (101.3 kPa)). -44- ------- For PDP-CVS, Vmlx is: Vmix - V x N(P -P,)(528 R) O B ^ (760 mm Hg) (T ) for SI units, Vmix - VQ x.N(Pg - P4)\(293.15 K) (101.3 kPa) (T ) P Where: V = Volume of gas pumped by the positive displacement pump, in cubic feet (m ) per revolution. This volume is dependent on the pressure differential across the positive displacement pump. N = Number of revolutions of the positive displacement pump during the test phase while samples are being collected. P_ = Barometric pressure, in mm Hg (kPa). D P, = Pressure depression below atmospheric measured at the inlet to the positive displacement pump, in mm Hg (kPa). T = Average temperature of dilute exhaust entering positive " displacement pump during test, R(K). (d) Example calculation of mass values of exhaust emissions using positive displacement pump: (1) For the "transient" phase of the cold start test assume the following: V "0.29344 ft /revolution; N=10,485; R=48.0%; R =48.2%; Pfi=762 mm Hg;° Pd=22.225 mm Hg; P4=70 mm Hg; T =570 R; HCe=105.8 ppm, carbon equivalent; NOx =11.2 ppm; CO =306\6 ppm; C0_ =1.43%; HCd=12.1 ppm; N0xd=0.8 ppm;6 C0)dm=15.3 ppm? Then: V . = (0.29344)^(10,485) (762-70) (528)/(760)(570)= mix 2595.0 ft per test phase. H = (43.478) (48.2) (22.225)/[762-(22.225 x 48.2/100)] KJJ = 1/[1-0.0047(62-75)] = 0.9424 C0g = [1-0.01925 (1.43)-0.000323 (48)] 306.0 = 293.4 ppm C0d = [1-0.000323 (48)] 15.3 = 15.1 ppm DF = 13.4/[1.43 + (105.8 + 293.4) x 10~4] = 9.116 -45- ------- HC - 105.8-12.1(1-1.9.116) - 95.03 ppm cone HC -• (2595) (16.33) (95.03/1,000,000) - 4.027 grams mass per test phase. NOx * 11.2-0.8 (1-1/9.116) - 10.49 ppm cone NOx - (2595) (54.16) (10.49/1,000,000) (0.9424) » 1.389 mass . grams per test phase. CO - 293.4-15.1 (1-1/9.116) - 280.0 ppm cone CO - (2595) (32.97) (280/1,000,000) * 23.96 grams per mass test phase. (2) For the stabilized portion of the cold start test assume that similar calculations resulted in the following: HC = 0.62 grams per test phase mass e> f t- NOx = 1.27 grams per test phase mass CO =5.98 'grams per test phase mass i (3) For the "transient" portion of the hot start test assume that similar calculations resulted in the following: HC = 0.51 grams per test phase or r- NOx =1.38 grams per test phase uiciss C0m = 5.01 grams per test phase UlclSS (4) Weighted mass emission results: HCwm * K°-43) (4.027) + ( grams per vehicle mile. %•&•• -••• '-9-~1-5 N°Xwm " t(0'43) d-389) + (0.57) (1.38) + 1.27]/7.5 = 0.354 grams per vehicle mile. C°wm = [(0.43) (23.96) + (0.57) (5.01) + 5.98J/7.5 = 2.55 grams per vehicle mile. -46- ------- |