( a) Application. Use instruments as specified in this section to measure work inputs and outputs during engine operation. We recommend that you use sensors, transducers, and meters that meet the specifications in Table 1 of § 1065.205. Note that your overall systems for measuring work inputs and outputs must meet the linearity verifications in § 1065.307. We recommend that you measure work inputs and outputs where they cross the system boundary as shown in Figure 1 of § 1065.210. The system boundary is different for air cooled engines than for liquid cooled engines. If you choose to measure work before or after a work conversion, relative to the system boundary, use good engineering judgment to estimate any work conversion losses in a way that avoids overestimation of total work. For example, if it is impractical to instrument the shaft of an exhaust turbine generating electrical work, you may decide to measure its converted electrical work. In this case, divide the electrical work by an accurate value of electrical generator efficiency (  < 1), or assume an efficiency of 1 (  = 1), which would over estimate brake specific emissions. Do not underestimate the generator's efficiency because this would result in an underestimation of brake specific emissions. In all cases, ensure that you are able to accurately demonstrate compliance with the applicable standards. 232 [ NOTE TO PRINTER   INSERT Figure 1 of § 1065.210 HERE] 233 ( b) Shaft work. Use speed and torque transducer outputs to calculate total work according to § 1065.650.

( 1) Speed. Use a magnetic or optical shaft position detector with a resolution of at least 60 counts per revolution, in combination with a frequency counter that rejects common mode noise.

( 2) Torque. You may use a variety of methods to determine engine torque. As needed, and based on good engineering judgment, compensate for torque induced by the inertia of accelerating and decelerating components connected to the flywheel, such as the drive shaft and dynamometer rotor. Use any of the following methods to determine engine torque:

( i) Measure torque by mounting a strain gage or similar instrument in line between the engine and dynamometer.

( ii) Measure torque by mounting a strain gage or similar instrument on a lever arm connected to the dynamometer housing.

( iii) Calculate torque from internal dynamometer signals, such as armature current, as long as you calibrate this measurement as described in § 1065.310.

( c) Electrical work. Use a watt hour meter output to calculate total work according to § 1065.650. Use a watt hour meter that outputs active power ( kW). Watt hour meters typically combine a Wheatstone bridge voltmeter and a Hall effect clamp on ammeter into a single microprocessor based instrument that analyzes and outputs several parameters, such as alternating or direct current voltage ( V), current ( A), power factor ( pf), apparent power ( VA), reactive power ( VAR), and active power ( W).

( d) Pump, compressor or turbine work. Use pressure transducer and flow meter outputs to calculate total work according to § 1065.650. For flow meters, see § 1065.220 through § 1065.248.

§ 1065.215 Pressure transducers, temperature sensors, and dewpoint sensors.

( a) Application. Use instruments as specified in this section to measure pressure, temperature, and dewpoint.

( b) Component requirements. We recommend that you use pressure transducers, temperature sensors, and dewpoint sensors that meet the specifications in Table 1 of § 1065.205. Note that your overall systems for measuring pressure, temperature, and dewpoint must meet the calibration and verifications in § 1065.315.

( c) Temperature. For PM balance environments or other precision temperature measurements over a narrow temperature range, we recommend thermistors. For other applications we recommend thermocouples that are not grounded to the thermocouple sheath. You may use other temperature sensors, such as resistive temperature detectors ( RTDs).

( d) Pressure. Pressure transducers must be located in a temperature controlled environment, or they must compensate for temperature changes over their expected operating range. Transducer materials must be compatible with the fluid being measured. For atmospheric pressure or other precision pressure measurements, we recommend either capacitance type, quartz crystal, or laserinterferometer transducers. For other applications, we recommend either strain gage or capacitance type pressure transducers. You may use other pressure measurement instruments, such as manometers, where appropriate. 234 ( e) Dewpoint. For PM stabilization environments, we recommend chilled surface hygrometers. For other applications, we recommend thin film capacitance sensors. You may use other dewpoint sensors, such as a wet bulb/ dry bulb psychrometer, where appropriate.

FLOW RELATED MEASUREMENTS § 1065.220 Fuel flow meter. ( a) Application. You may use fuel flow in combination with a chemical balance of carbon ( or oxygen) between the fuel, inlet air, and raw exhaust to calculate raw exhaust flow as described in § 1065.650, as follows:

( 1) Use the actual value of calculated raw exhaust flow rate in the following cases:

( i) For multiplying raw exhaust flow rate with continuously sampled concentrations.

( ii) For multiplying total raw exhaust flow with batch sampled concentrations.

( 2) In the following cases, you may use a fuel flow meter signal that does not give the actual value of raw exhaust, as long as it is linearly proportional to the exhaust molar flow rate's actual calculated value:

( i) For feedback control of a proportional sampling system, such as a partial flow dilution system.

( ii) For multiplying with continuously sampled gas concentrations, if the same signal is used in a chemical balance calculation to determine work from brake specific fuel consumption and fuel consumed.

( b) Component requirements. We recommend that you use a fuel flow meter that meets the specifications in Table 1 of § 1065.205. We recommend a fuel flow meter that measures mass directly, such as one that relies on gravimetric or inertial measurement principles. This may involve using a meter with one or more scales for weighing fuel or using a Coriolis meter. Note that your overall system for measuring fuel flow must meet the linearity verification in § 1065.307 and the calibration and verifications in § 1065.320.

( c) Recirculating fuel. In any fuel flow measurement, account for any fuel that bypasses the engine or returns from the engine to the fuel storage tank.

( d) Flow conditioning. For any type of fuel flow meter, condition the flow as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. You may accomplish this by using a sufficient length of straight tubing ( such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, straightening fins, or pneumatic pulsation dampeners to establish a steady and predictable velocity profile upstream of the meter.

§ 1065.225 Intake air flow meter. ( a) Application. You may use an intake air flow meter in combination with a chemical balance of carbon ( or oxygen) between the fuel, inlet air, and raw exhaust to calculate raw exhaust flow as described in § 1065.650, as follows:

( 1) Use the actual value of calculated raw exhaust in the following cases:

( i) For multiplying raw exhaust flow rate with continuously sampled concentrations.

( ii) For multiplying total raw exhaust flow with batch sampled concentrations. 235 ( 2) In the following cases, you may use an intake air flow meter signal that does not give the actual value of raw exhaust, as long as it is linearly proportional to the exhaust flow rate's actual calculated value:

( i) For feedback control of a proportional sampling system, such as a partial flow dilution system.

( ii) For multiplying with continuously sampled gas concentrations, if the same signal is used in a chemical balance calculation to determine work from brake specific fuel consumption and fuel consumed.

( b) Component requirements. We recommend that you use an intake air flow meter that meets the specifications in Table 1 of § 1065.205. This may include a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a thermal mass meter, an averaging Pitot tube, or a hot wire anemometer. Note that your overall system for measuring intake air flow must meet the linearity verification in § 1065.307 and the calibration in § 1065.325.

( c) Flow conditioning. For any type of intake air flow meter, condition the flow as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. You may accomplish this by using a sufficient length of straight tubing ( such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, orifice plates or straightening fins to establish a predictable velocity profile upstream of the meter.

§ 1065.230 Raw exhaust flow meter.

( a) Application. You may use measured raw exhaust flow, as follows:

( 1) Use the actual value of calculated raw exhaust in the following cases:

( i) Multiply raw exhaust flow rate with continuously sampled concentrations.

( ii) Multiply total raw exhaust with batch sampled concentrations.

( 2) In the following cases, you may use a raw exhaust flow meter signal that does not give the actual value of raw exhaust, as long as it is linearly proportional to the exhaust flow rate's actual calculated value:

( i) For feedback control of a proportional sampling system, such as a partial flow dilution system.

( ii) For multiplying with continuously sampled gas concentrations, if the same signal is used in a chemical balance calculation to determine work from brake specific fuel consumption and fuel consumed.

( b) Component requirements. We recommend that you use a raw exhaust flow meter that meets the specifications in Table 1 of § 1065.205. This may involve using an ultrasonic flow meter, a subsonic venturi, an averaging Pitot tube, a hot wire anemometer, or other measurement principle. This would generally not involve a laminar flow element or a thermal mass meter. Note that your overall system for measuring raw exhaust flow must meet the linearity verification in § 1065.307 and the calibration and verifications in § 1065.330. Any raw exhaust meter must be designed to appropriately compensate for changes in the raw exhaust's thermodynamic, fluid, and compositional states.

( c) Flow conditioning. For any type of raw exhaust flow meter, condition the flow as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. You may accomplish this by using a sufficient length of straight tubing ( such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, orifice plates or straightening fins to establish a predictable velocity profile upstream of the meter. 236 ( d) Exhaust cooling. You may cool raw exhaust upstream of a raw exhaust flow meter, as long as you observe all the following provisions:

( 1) Do not sample PM downstream of the cooling.

( 2) If cooling causes exhaust temperatures above 202

C to decrease to below 180

C, do not sample NMHC downstream of the cooling for compression ignition engines, 2 stroke sparkignition engines, and 4 stroke spark ignition engines below 19 kW.

( 3) If cooling causes aqueous condensation, do not sample NO x downstream of the cooling unless the cooler meets the performance verification in § 1065.376.

( 4) If cooling causes aqueous condensation before the flow reaches a flow meter, measure dewpoint, T dew and pressure, p total at the flow meter inlet. Use these values in emission calculations according to § 1065.650.

§ 1065.240 Dilution air and diluted exhaust flow meters.

( a) Application. Use a diluted exhaust flow meter to determine instantaneous diluted exhaust flow rates or total diluted exhaust flow over a test interval. You may use the difference between a diluted exhaust flow meter and a dilution air meter to calculate raw exhaust flow rates or total raw exhaust flow over a test interval.

( b) Component requirements. We recommend that you use a diluted exhaust flow meter that meets the specifications in Table 1 of § 1065.205. Note that your overall system for measuring diluted exhaust flow must meet the linearity verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use the following meters:

( 1) For constant volume sampling ( CVS) of the total flow of diluted exhaust, you may use a critical flow venturi ( CFV) or multiple critical flow venturis arranged in parallel, a positivedisplacement pump ( PDP), a subsonic venturi ( SSV), or an ultrasonic flow meter ( UFM). Combined with an upstream heat exchanger, either a CFV or a PDP will also function as a passive flow controller in a CVS system. However, you may also combine any flow meter with any active flow control system to maintain proportional sampling of exhaust constituents. You may control the total flow of diluted exhaust, or one or more sample flows, or a combination of these flow controls to maintain proportional sampling.

( 2) For any other dilution system, you may use a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a critical flow venturi or multiple critical flow venturis arranged in parallel, a positive displacement meter, a thermal mass meter, an averaging Pitot tube, or a hot wire anemometer.

( c) Flow conditioning. For any type of diluted exhaust flow meter, condition the flow as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. For some meters, you may accomplish this by using a sufficient length of straight tubing ( such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, orifice plates or straightening fins to establish a predictable velocity profile upstream of the meter.

( d) Exhaust cooling. You may cool diluted exhaust upstream of a raw exhaust flow meter, as long as you observe all the following provisions:

( 1) Do not sample PM downstream of the cooling.

( 2) If cooling causes exhaust temperatures above 202

C to decrease to below 180

C, do not sample NMHC downstream of the cooling for compression ignition engines, 2 stroke sparkignition engines, and 4 stroke spark ignition engines below 19 kW. 237 ( 3) If cooling causes aqueous condensation, do not sample NO x downstream of the cooling unless the cooler meets the performance verification in § 1065.376.

( 4) If cooling causes aqueous condensation before the flow reaches a flow meter, measure dewpoint, T dew and pressure, p total at the flow meter inlet. Use these values in emission calculations according to § 1065.650.

§ 1065.245 Sample flow meter for batch sampling.

( a) Application. Use a sample flow meter to determine sample flow rates or total flow sampled into a batch sampling system over a test interval. You may use the difference between a diluted exhaust sample flow meter and a dilution air meter to calculate raw exhaust flow rates or total raw exhaust flow over a test interval.

( b) Component requirements. We recommend that you use a sample flow meter that meets the specifications in Table 1 of § 1065.205. This may involve a laminar flow element, an ultrasonic flow meter, a subsonic venturi, a critical flow venturi or multiple critical flow venturis arranged in parallel, a positive displacement meter, a thermal mass meter, an averaging Pitot tube, or a hotwire anemometer. Note that your overall system for measuring sample flow must meet the linearity verification in § 1065.307. For the special case where CFVs are used for both the diluted exhaust and sample flow measurements and their upstream pressures and temperatures remain similar during testing, you do not have to quantify the flow rate of the sample flow CFV. In this special case, the sample flow CFV inherently flow weights the batch sample relative to the diluted exhaust CFV.

( c) Flow conditioning. For any type of sample flow meter, condition the flow as needed to prevent wakes, eddies, circulating flows, or flow pulsations from affecting the accuracy or repeatability of the meter. For some meters, you may accomplish this by using a sufficient length of straight tubing ( such as a length equal to at least 10 pipe diameters) or by using specially designed tubing bends, orifice plates or straightening fins to establish a predictable velocity profile upstream of the meter.

§ 1065.248 Gas divider. ( a) Application. You may use a gas divider to blend calibration gases.

( b) Component requirements. Use a gas divider that blends gases to the specifications of § 1065.750 and to the flow weighted concentrations expected during testing. You may use critical flow gas dividers, capillary tube gas dividers, or thermal mass meter gas dividers. Note that your overall gas divider system must meet the linearity verification in § 1065.307.

CO AND CO 2 MEASUREMENTS § 1065.250 Nondispersive infra red analyzer.

( a) Application. Use a nondispersive infra red ( NDIR) analyzer to measure CO and CO 2 concentrations in raw or diluted exhaust for either batch or continuous sampling.

( b) Component requirements. We recommend that you use an NDIR analyzer that meets the specifications in Table 1 of § 1065.205. Note that your NDIR based system must meet the calibration and verifications in § 1065.350 and § 1065.355 and it must also meet the linearity verification in § 1065.307. You may use an NDIR analyzer that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. 238 The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

HYDROCARBON MEASUREMENTS § 1065.260 Flame ionization detector. ( a) Application. Use a flame ionization detector ( FID) analyzer to measure hydrocarbon concentrations in raw or diluted exhaust for either batch or continuous sampling. Determine hydrocarbon concentrations on a carbon number basis of one, C 1. Determine methane and nonmethane hydrocarbon values as described in paragraph ( e) of this section. See subpart I of this part for special provisions that apply to measuring hydrocarbons when testing with oxygenated fuels.

( b) Component requirements. We recommend that you use a FID analyzer that meets the specifications in Table 1 of § 1065.205. Note that your FID based system for measuring THC, THCE, or CH 4 must meet all of the verifications for hydrocarbon measurement in subpart D of this part, and it must also meet the linearity verification in § 1065.307. You may use a FID that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

( c) Heated FID analyzers. For diesel fueled engines, two stroke spark ignition engines, and fourstroke spark ignition engines below 19 kW, you must use heated FID analyzers that maintain all surfaces that are exposed to emissions at a temperature of ( 191 + 11)

C.

( d) FID fuel and burner air. Use FID fuel and burner air that meet the specifications of § 1065.750. Do not allow the FID fuel and burner air to mix before entering the FID analyzer to ensure that the FID analyzer operates with a diffusion flame and not a premixed flame.

( e) Methane. FID analyzers measure total hydrocarbons ( THC). To determine nonmethane hydrocarbons ( NMHC), quantify methane, CH 4, either with a nonmethane cutter and a FID analyzer as described in § 1065.265, or with a gas chromatograph as described in § 1065.267. Instead of measuring methane, you may assume that 2 % of measured total hydrocarbons is methane, as described in § 1065.660. For a FID analyzer used to determine NMHC, determine its response factor to CH 4, RF CH4, as described in § 1065.360. Note that NMHC related calculations are described in § 1065.660.

§ 1065.265 Nonmethane cutter.

( a) Application. You may use a nonmethane cutter to measure CH 4 with a FID analyzer. A nonmethane cutter oxidizes all nonmethane hydrocarbons to CO 2 and H 2 O. You may use a nonmethane cutter for raw or diluted exhaust for batch or continuous sampling.

( b) System performance. Determine nonmethane cutter performance as described in § 1065.365 and use the results to calculate NMHC emission in § 1065.660.

( c) Configuration. Configure the nonmethane cutter with a bypass line for the verification described in § 1065.365.

( d) Optimization. You may optimize a nonmethane cutter to maximize the penetration of CH 4 and the oxidation of all other hydrocarbons. You may humidify a sample and you may dilute a sample with purified air or oxygen ( O 2) upstream of the nonmethane cutter to optimize its performance. You must account for any sample humidification and dilution in emission calculations. 239 § 1065.267 Gas chromatograph.

( a) Application. You may use a gas chromatograph to measure CH 4 concentrations of diluted exhaust for batch sampling. While you may also use a nonmethane cutter to measure CH 4, as described in § 1065.265, use a reference procedure based on a gas chromatograph for comparison with any proposed alternate measurement procedure under § 1065.10.

( b) Component requirements. We recommend that you use a gas chromatograph that meets the specifications in Table 1 of § 1065.205, and it must also meet the linearity verification in § 1065.307.

NO X MEASUREMENTS § 1065.270 Chemiluminescent detector.

( a) Application. You may use a chemiluminescent detector ( CLD) to measure NO x concentration in raw or diluted exhaust for batch or continuous sampling. We generally accept a CLD for NO x measurement, even though it measures only NO and NO 2, when coupled with an NO 2 to NO converter, since conventional engines and aftertreatment systems do not emit significant amounts of NO x species other than NO and NO 2. Measure other NO x species if required by the standardsetting part. While you may also use other instruments to measure NO x, as described in § 1065.272, use a reference procedure based on a chemiluminescent detector for comparison with any proposed alternate measurement procedure under § 1065.10.

( b) Component requirements. We recommend that you use a CLD that meets the specifications in Table 1 of § 1065.205. Note that your CLD based system must meet the quench verification in § 1065.370 and it must also meet the linearity verification in § 1065.307. You may use a heated or unheated CLD, and you may use a CLD that operates at atmospheric pressure or under a vacuum. You may use a CLD that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

( c) NO 2 to NO converter. Place upstream of the CLD an internal or external NO 2 to NO converter that meets the verification in § 1065.378. Configure the converter with a bypass to facilitate this verification.

( d) Humidity effects. You must maintain all CLD temperatures to prevent aqueous condensation. To remove humidity from a sample upstream of a CLD, use one of the following configurations:

( 1) Connect a CLD downstream of any dryer or chiller that is downstream of an NO 2 to NO converter that meets the verification in § 1065.378.

( 2) Connect a CLD downstream of any dryer or thermal chiller that meets the verification in § 1065.376.

( e) Response time. You may use a heated CLD to improve CLD response time.

§ 1065.272 Nondispersive ultraviolet analyzer. ( a) Application. You may use a nondispersive ultraviolet ( NDUV) analyzer to measure NO x concentration in raw or diluted exhaust for batch or continuous sampling. We generally accept an NDUV for NO x measurement, even though it measures only NO and NO 2, since conventional 240 engines and aftertreatment systems do not emit significant amounts of other NO x species. Measure other NO x species if required by the standard setting part.

( b) Component requirements. We recommend that you use an NDUV analyzer that meets the specifications in Table 1 of § 1065.205. Note that your NDUV based system must meet the verifications in § 1065.372 and it must also meet the linearity verification in § 1065.307. You may use a NDUV analyzer that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

( c) NO 2 to NO converter. If your NDUV analyzer measures only NO, place upstream of the NDUV analyzer an internal or external NO 2 to NO converter that meets the verification in § 1065.378. Configure the converter with a bypass to facilitate this verification.

( d) Humidity effects. You must maintain NDUV temperature to prevent aqueous condensation, unless you use one of the following configurations:

( 1) Connect an NDUV downstream of any dryer or chiller that is downstream of an NO 2 to NO converter that meets the verification in § 1065.378.

( 2) Connect an NDUV downstream of any dryer or thermal chiller that meets the verification in § 1065.376.

O 2 MEASUREMENTS § 1065.280 Paramagnetic and magnetopneumatic O2 detection analyzers.

( a) Application. You may use a paramagnetic detection ( PMD) or magnetopneumatic detection MPD) analyzer to measure O 2 concentration in raw or diluted exhaust for batch or continuous sampling. You may use O 2 measurements with intake air or fuel flow measurements to calculate exhaust flow rate according to § 1065.650.

( b) Component requirements. We recommend that you use a PMD/ MPD analyzer that meets the specifications in Table 1 of § 1065.205. Note that it must meet the linearity verification in § 1065.307. You may use a PMD/ MPD that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

AIR TO FUEL RATIO MEASUREMENTS § 1065.284 Zirconia ( ZrO2) analyzer.

( a) Application. You may use a zirconia ( ZrO 2) analyzer to measure air to fuel ratio in raw exhaust for continuous sampling. You may use O 2 measurements with intake air or fuel flow measurements to calculate exhaust flow rate according to § 1065.650.

( b) Component requirements. We recommend that you use a ZrO 2 analyzer that meets the specifications in Table 1 of § 1065.205. Note that your ZrO 2 based system must meet the linearity verification in § 1065.307. You may use a Zirconia analyzer that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias. 241 PM MEASUREMENTS § 1065.290 PM gravimetric balance.

( a) Application. Use a balance to weigh net PM on a sample medium for laboratory testing.

( b) Component requirements. We recommend that you use a balance that meets the specifications in Table 1 of § 1065.205. Note that your balance based system must meet the linearity verification in § 1065.307. If the balance uses internal calibration weights for routine spanning and linearity verifications, the calibration weights must meet the specifications in § 1065.790. While you may also use an inertial balance to measure PM, as described in § 1065.295, use a reference procedure based on a gravimetric balance for comparison with any proposed alternate measurement procedure under § 1065.10.

( c) Pan design. We recommend that you use a balance pan designed to minimize corner loading of the balance, as follows:

( 1) Use a pan that centers the PM sample on the weighing pan. For example, use a pan in the shape of a cross that has upswept tips that center the PM sample media on the pan.

( 2) Use a pan that positions the PM sample as low as possible.

( d) Balance configuration. Configure the balance for optimum settling time and stability at your location.

§ 1065.295 PM inertial balance for field testing analysis.

( a) Application. You may use an inertial balance to quantify net PM on a sample medium for field testing.

( b) Component requirements. We recommend that you use a balance that meets the specifications in Table 1 of § 1065.205. Note that your balance based system must meet the linearity verification in § 1065.307. If the balance uses an internal calibration process for routine spanning and linearity verifications, the process must be NIST traceable. You may use an inertial PM balance that has compensation algorithms that are functions of other gaseous measurements and the engine's known or assumed fuel properties. The target value for any compensation algorithm is 0.0 % ( that is, no bias high and no bias low), regardless of the uncompensated signal's bias.

Subpart D   Calibrations and Verifications § 1065.301 Overview and general provisions. ( a) This subpart describes required and recommended calibrations and verifications of measurement systems. See subpart C of this part for specifications that apply to individual instruments.

( b) You must generally use complete measurement systems when performing calibrations or verifications in this subpart. For example, this would generally involve evaluating instruments based on values recorded with the complete system you use for recording test data, including analog to digital converters. For some calibrations and verifications, we may specify that you disconnect part of the measurement system to introduce a simulated signal.

( c) If we do not specify a calibration or verification for a portion of a measurement system, calibrate that portion of your system and verify its performance at a frequency consistent with any recommendations from the measurement system manufacturer, consistent with good engineering judgment. 242 ( d) Use NIST traceable standards to the tolerances we specify for calibrations and verifications. Where we specify the need to use NIST traceable standards, you may alternatively ask for our approval to use international standards that are not NIST traceable.

§ 1065.303 Summary of required calibration and verifications ( a) The following table summarizes the required and recommended calibrations and verifications described in this subpart and indicates when these have to be performed:

Table 1 of § 1065.303   Summary of required calibration and verifications Type of calibration or verification Minimum frequencya § 1065.305: accuracy, repeatability and noise Accuracy: Not required, but recommended for initial installation.

Repeatability: Not required, but recommended for initial installation.

Noise: Not required, but recommended for initial installation.

§ 1065.307: linearity Speed: Upon initial installation, within 370 days before testing and after major maintenance.

Torque: Upon initial installation, within 370 days before testing and after major maintenance.

Electrical power: Upon initial installation, within 370 days before testing and after major maintenance.

Clean gas and diluted exhaust flows: Upon initial installation, within 370 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance.

Raw exhaust flow: Upon initial installation, within 185 days before testing and after major maintenance, unless flow is verified by propane check or by carbon or oxygen balance.

Gas analyzers: Upon initial installation, within 35 days before testing and after major maintenance.

PM balance: Upon initial installation, within 370 days before testing and after major maintenance.

Stand alone pressure and temperature: Upon initial installation, within 370 days before testing and after major maintenance.

§ 1065.308: Continuous analyzer system response and recording Upon initial installation, after system reconfiguration, and after major maintenance.

§ 1065.309: Continuous analyzer uniform response Upon initial installation, after system reconfiguration, and after major maintenance.

§ 1065.310: torque Upon initial installation and after major maintenance.

§ 1065.315: pressure, temperature, dewpoint Upon initial installation and after major maintenance.

§ 1065.320: fuel flow Upon initial installation and after major maintenance.

§ 1065.325: intake flow Upon initial installation and after major maintenance.

§ 1065.330: exhaust flow Upon initial installation and after major maintenance.

§ 1065.340: diluted exhaust flow ( CVS) Upon initial installation and after major maintenance. 243 § 1065.341: CVS and batch sampler verification Upon initial installation, within 35 days before testing, and after major maintenance.

§ 1065.345: vacuum leak Before each laboratory test according to subpart F of this part and before each field test according to subpart J of this part.

§ 1065.350: CO2 NDIR H2O interference Upon initial installation and after major maintenance.

§ 1065.355: CO NDIR CO2 and H2O interference Upon initial installation and after major maintenance.

§ 1065.360: FID optimization, etc. Calibrate, optimize, and determine CH4 response: upon initial installation and after major maintenance.

Verify CH4 response: upon initial installation, within 185 days before testing, and after major maintenance.

§ 1065.362: raw exhaust FID O2 interference Upon initial installation, after FID optimization according to § 1065.360, and after major maintenance.

§ 1065.365: nonmethane cutter penetration Upon initial installation, within 185 days before testing, and after major maintenance.

§ 1065.370: CLD CO2 and H2O quench Upon initial installation and after major maintenance.

§ 1065.372: NDUV HC and H2O interference Upon initial installation and after major maintenance.

§ 1065.376: chiller NO2 penetration Upon initial installation and after major maintenance.

§ 1065.378: NO2 to NO converter conversion Upon initial installation, within 35 days before testing, and after major maintenance.

§ 1065.390: PM balance and weighing Independent verification: upon initial installation, within 370 days before testing, and after major maintenance.

Zero, span, and reference sample verifications: within 12 hours of weighing, and after major maintenance.

§ 1065.395: Inertial PM balance and weighing Independent verification: upon initial installation, within 370 days before testing, and after major maintenance.

Other verifications: upon initial installation and after major maintenance.

aPerform calibrations and verifications more frequently, according to measurement system manufacturer instructions and good engineering judgment.

§ 1065.305 Verifications for accuracy, repeatability, and noise.

( a) This section describes how to determine the accuracy, repeatability, and noise of an instrument. Table 1 of § 1065.205 specifies recommended values for individual instruments.

( b) We do not require you to verify instrument accuracy, repeatability, or noise. However, it may be useful to consider these verifications to define a specification for a new instrument, to verify the performance of a new instrument upon delivery, or to troubleshoot an existing instrument. 244 ( c) In this section we use the letter " y" to denote a generic measured quantity, the superscript over bar to denote an arithmetic mean ( such as ), and the subscript " ref" to denote the reference i yy quantity being measured.

( d) Conduct these verifications as follows:

( 1) Prepare an instrument so it operates at its specified temperatures, pressures, and flows. Perform any instrument linearization or calibration procedures prescribed by the instrument manufacturer.

( 2) Zero the instrument as you would before an emission test by introducing a zero signal. Depending on the instrument, this may be a zero concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a zero gas that meets the specifications of § 1065.750.

( 3) Span the instrument as you would before an emission test by introducing a span signal. Depending on the instrument, this may be a span concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a span gas that meets the specifications of § 1065.750.

( 4) Use the instrument to quantify a NIST traceable reference quantity, y ref . For gas analyzers the reference gas must meet the specifications of § 1065.750. Select a reference quantity near the mean value expected during testing. For all gas analyzers, use a quantity near the flow weighted mean concentration expected at the standard or expected during testing, whichever is greater. For a noise verfication, use the same zero gas from paragraph ( e) of this section as the reference quantity. In all cases, allow time for the instrument to stabilize while it measures the reference quantity. Stabilization time may include time to purge an instrument and time to account for its response.

( 5) Sample and record values for 30 seconds, record the arithmetic mean, , and record the i i yy standard deviation, , of the recorded values. Refer to § 1065.602 for an example of i   calculating arithmetic mean and standard deviation.

( 6) Also, if the reference quantity is not absolutely constant, which might be the case with a reference flow, sample and record values of y refi for 30 seconds and record the arithmetic mean of the values, . Refer to § 1065.602 for an example of calculating arithmetic mean. ref y ( 7) Subtract the reference value, y ref ( or ), from the arithmetic mean, . Record this ref y i i yy value as the error,   i .

( 8) Repeat the steps specified in paragraphs ( e)( 2) through ( 6) of this section until you have ten arithmetic means ( , , ,... ), ten standard deviations, (   1 ,   2 ,   i ,...   10), and ten 1 y 2 y i y 10 y errors (   1 ,   2 ,   i ,...   10). ( 9) Use the following values to quantify your measurements:

( i) Accuracy. Instrument accuracy is the absolute difference between the reference quantity, y ref ( or ), and the arithmetic mean of the ref y Refer to the example of an accuracy calculation i y in § 1065.602. We recommend that instrument accuracy be within the specifications in Table 1 of § 1065.205.

( ii) Repeatability. Repeatability is two times the standard deviation of the ten errors ( that is, repeatability = 2

) . Refer to the example of a standard deviation calculation in     245 § 1065.602. We recommend that instrument repeatability be within the specifications in Table 1 of § 1065.205.

( iii) Noise. Noise is two times the root mean square of the ten standard deviations ( that is,

noise = 2 ) when the reference signal is a zero quantity signal. Refer to the example rms

of a root mean square calculation in § 1065.602. We recommend that instrument noise be within the specifications in Table 1 of § 1065.205. Use this value in the noise correction specified in § 1065.657.

( 10) You may use a measurement instrument that does not meet the accuracy, repeatability, or noise specifications in Table 1 of § 1065.205, as long as you meet the following criteria:

( i) Your measurement systems meet all the other required calibration, verification, and validation specifications in subparts D, F, and J of this part, as applicable.

( ii) The measurement deficiency does not adversely affect your ability to demonstrate compliance with the applicable standards.

§ 1065.307 Linearity verification.

( a) Scope and frequency. Perform a linearity verification on each measurement system listed in Table 1 of this section at least as frequently as indicated in the table, consistent with measurement system manufacturer recommendations and good engineering judgment. Note that this linearity verification may replace requirements we previously referred to as " calibrations". The intent of a linearity verification is to determine that a measurement system responds proportionally over the measurement range of interest. A linearity verification generally consists of introducing a series of at least 10 reference values to a measurement system. The measurement system quantifies each reference value. The measured values are then collectively compared to the reference values by using a least squares linear regression and the linearity criteria specified in Table 1 of this section.

( b) Performance requirements. If a measurement system does not meet the applicable linearity criteria in Table 1 of this section, correct the deficiency by re calibrating, servicing, or replacing components as needed. Before you may use a measurement system that does not meet linearity criteria, you must demonstrate to us that the deficiency does not adversely affect your ability to demonstrate compliance with the applicable standards.

( c) Procedure. Use the following linearity verification protocol, or use good engineering judgment to develop a different protocol that satisfies the intent of this section, as described in paragraph ( a) of this section:

( 1) In this paragraph ( c), we use the letter " y" to denote a generic measured quantity, the superscript over bar to denote an arithmetic mean ( such as ), and the subscript " ref" to y denote the known or reference quantity being measured.

( 2) Operate a measurement system at its specified temperatures, pressures, and flows. This may include any specified adjustment or periodic calibration of the measurement system.

( 3) Zero the instrument as you would before an emission test by introducing a zero signal. Depending on the instrument, this may be a zero concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a zero gas that meets the specifications of § 1065.750 and introduce it directly at the analyzer port.

( 4) Span the instrument as you would before an emission test by introducing a span signal. Depending on the instrument, this may be a span concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a 246 span gas that meets the specifications of § 1065.750 and introduce it directly at the analyzer port.

( 5) After spanning the instrument, check zero with the same signal you used in paragraph ( c)( 3) of this section. Based on the zero reading, use good engineering judgment to determine whether or not to rezero and or re span the instrument before proceeding to the next step.

( 5) Use instrument manufacturer recommendations and good engineering judgment to select at least 10 reference values, y refi, that are within the range from zero to the highest values expected during emission testing. We recommend selecting a zero reference signal as one of the reference values of the linearity verification.

( 6) Use instrument manufacturer recommendations and good engineering judgment to select the order in which you will introduce the series of reference values. For example you may select the reference values randomly to avoid correlation with previous measurements, you may select reference values in ascending or descending order to avoid long settling times of reference signals, or as another example you may select values to ascend and then descend which might incorporate the effects of any instrument hysteresis into the linearity verification.

( 7) Generate reference quantities as described in paragraph ( d) of this section. For gas analyzers, use gas concentrations known to be within the specifications of § 1065.750 and introduce them directly at the analyzer port.

( 8) Introduce a reference signal to the measurement instrument.

( 9) Allow time for the instrument to stabilize while it measures the reference value. Stabilization time may include time to purge an instrument and time to account for its response.

( 10) At a recording frequency of at least f Hz, specified in Table 1 of § 1065.205, measure the reference value for 30 seconds and record the arithmetic mean of the recorded values, . i y Refer to § 1065.602 for an example of calculating an arithmetic mean.

( 11) Repeat steps in paragraphs of this section until all reference quantities are measured.

( 12) Use the arithmetic means, , and reference values, y refi , to calculate least squares linear i y regression parameters and statistical values to compare to the minimum performance criteria specified in Table 1 of this section. Use the calculations described in § 1065.602.

( d) Reference signals. This paragraph ( d) describes recommended methods for generating reference values for the linearity verification protocol in paragraph ( c) of this section. Use reference values that simulate actual values, or introduce an actual value and measure it with a reference measurement system. In the latter case, the reference value is the value reported by the reference measurement system. Reference values and reference measurement systems must be NIST traceable. We recommend using calibration reference quantities that are NIST traceable within 0.5 % uncertainty, if not specified otherwise in other sections of this part 1065. Use the following recommended methods to generate reference values or use good engineering judgment to select a different reference:

( 1) Engine speed. Run the engine or dynamometer at a series of steady state speeds and use a strobe, a photo tachometer, or a laser tachometer to record reference speeds.

( 2) Engine torque. Use a series of calibration weights and a calibration lever arm to simulate engine torque. You may instead use the engine or dynamometer itself to generate a nominal torque that is measured by a reference load cell or proving ring in series with the torquemeasurement system. In this case use the reference load cell measurement as the reference 247 value. Refer to § 1065.310 for a torque calibration procedure similar to the linearity verification in this section.

( 3) Electrical work. Use a controlled source of current and a watt hour standard reference meter. Complete calibration systems that contain a current source and a reference watt hour meter are commonly used in the electrical power distribution industry and are therefore commercially available.

( 4) Fuel rate. Operate the engine at a series of constant fuel flow rates or re circulate fuel back to a tank via the fuel flow meter at different flow rates. Use a gravimetric reference measurement ( such as a scale, balance, or mass comparator) at the inlet to the fuelmeasurement system. Use a stopwatch or timer to measure the time intervals over which reference masses of fuel are introduced to the fuel measurement system. The reference fuel mass divided by the time interval is the reference fuel flow rate.

( 5) Flow rates   inlet air, dilution air, diluted exhaust, raw exhaust, or sample flow. Use a reference flow meter with a blower or pump to simulate flow rates. Use a restrictor, diverter valve, a variable speed blower or a variable speed pump to control the range of flow rates. Use the reference meter's response as the reference values.

( i) Reference flow meters. Because the flow range requirements for these various flows are large, we allow a variety of reference meters. For example, for diluted exhaust flow for a full flow dilution system, we recommend a reference subsonic venturi flow meter with a restrictor valve and a blower to simulate flow rates. For inlet air, dilution air, diluted exhaust for partial flow dilution, raw exhaust, or sample flow, we allow reference meters such as critical flow orifices, critical flow venturis, laminar flow elements, master mass flow standards, or Roots meters. Make sure the reference meter is calibrated by the flow meter manufacturer and its calibration is NIST traceable. If you use the difference of two flow measurements to determine a net flow rate, you may use one of the measurements as a reference for the other.

( ii) Reference flow values. Because the reference flow is not absolutely constant, sample and record values of for 30 seconds and use the arithmetic mean of the values, , refi n

ref n

as the reference value. Refer to § 1065.602 for an example of calculating arithmetic mean.

( 6) Gas division. Use one of the two reference signals:

( i) At the outlet of the gas division system, connect a gas analyzer that meets the linearity verification described in this section and has not been linearized via the gas divider being verified. For example, verify the linearity of an analyzer using a series of reference analytical gases directly from compressed gas cylinders that meet the specifications of § 1065.750. We recommend using a FID analyzer or a PMD/ MPD O 2 analyzer because of their inherent linearity. Operate this analyzer consistent with how you would operate it during an emission test. Connect a span gas to the gas divider inlet. Use the gas division system to divide the span gas with purified air or nitrogen. Select gas divisions that you typically use. Use a selected gas division as the measured value. Use the analyzer response divided by the span gas concentration as the reference gas division value. Because the instrument response is not absolutely constant, sample and record values of x refi for 30 seconds and use the arithmetic mean of the values, , as the reference value. ref x Refer to § 1065.602 for an example of calculating arithmetic mean.

( ii) Using good engineering judgment and gas divider manufacturer recommendations, use one or more reference flow meters to verify the measured flow rates of the gas divider. 248 ( 7) Continuous constituent concentration. For reference values, use a series of gas cylinders of known gas concentration or use a gas division system that is known to be linear with a span gas. Gas cylinders, gas division systems, and span gases that you use for reference values must meet the specifications of § 1065.750.

Table 1 of § 1065.307   Measurement systems that require linearity verifications Measurement System Quantity Minimum verification frequencya Linearity Criteria | a 0 | b a 1 c SEEb r2 Engine speed f n Within 370 days before testing < 0.05 % · nmax f 0.98 1.02 < 2 % · nmax f > 0.990 Engine torque T Within 370 days before testing < 1 % · max T 0.98 1.02 < 2 % · max T > 0.990 Electrical work W Within 370 days before testing < 1 % · max T 0.98 1.02 < 2 % · max max T n

> 0.990 Fuel flow rate m n

Within 370 days before testingd < 1 % · max m

0.98 1.02 e < 2 % · max m

> 0.990 Intake air flow rate nn

Within 370 days before testing d < 1 % · max n

0.98 1.02 e < 2 % · max n

> 0.990 Dilution air flow rate n

Within 370 days before testing d < 1 % · max n

0.98 1.02 < 2 % · max n

> 0.990 Diluted exhaust flow rate n

Within 370 days before testing d < 1 % · max min n x

0.98 1.02 < 2 % · max n

> 0.990 Raw exhaust flow rate n

Within 185 days before testing d < 1 % · max n

0.98 1.02 e < 2 % · max n

> 0.990 Batch sampler flow rates ref nn

Within 370 days before testing d < 1 % · max n

0.98 1.02 < 2 % · max max n x

> 0.990 Gas dividers x Within 370 days before testing < 0.5 % · max x 0.98 1.02 < 2 % · max x > 0.990 All gas analyzers x Within 35 days before testing < 0.5 % · max m 0.99 1.01 < 1 % · max x > 0.998 PM balance m Within 370 days before testing < 1 % · max m 0.99 1.01 < 1 % · max m > 0.998 Stand alone pressures p Within 370 days before testing < 1 % · max m 0.99 1.01 < 1 % · max m > 0.998 Stand alone temperatures T Within 370 days before testing < 1 % · max m 0.99 1.01 < 1 % · max m > 0.998 a Perform a linearity verification more frequently if the instrument manufacturer recommends it or based on good engineering judgment.

b " max" refers to the maximum value expected during a test   the maximum value used for the linearity verification.

c The specified ranges are inclusive. For example, a specified range of 0.98 1.02 for a 1 means 0.98< a 1< 1.02.

d These linearity verifications are not required for systems that pass the flow rate verification for diluted exhaust as described in § 1065.341 ( the propane check) or for systems that agree within + 2 % based on a chemical balance of carbon or oxygen of the intake air, fuel, and exhaust.

e a 0 and a 1 for these quantities are required only if the actual value of the quantity is required, as opposed to a signal that is only linearly proportional to the actual value. 249 § 1065.308 Continuous gas analyzer system response and updating recording verification. ( a) Scope and frequency. Perform this verification after installing or replacing a gas analyzer that you use for continuous sampling. Also perform this verification if you reconfigure your system in a way that would change system response. For example, perform this verification if you add a significant volume to the transfer lines by increasing their length or adding a filter; or if you change the frequency at which you sample and record gas analyzer concentrations.

( b) Measurement principles. This test verifies that the updating and recording frequencies match the overall system response to a rapid change in the value of concentrations at the sample probe. Gas analyzer systems must be optimized such that their overall response to a rapid change in concentration is updated and recorded at an appropriate frequency to prevent loss of information.

( c) System requirements. To demonstrate acceptable updating and recording with respect to the system's overall response, use good engineering judgment to select one of the following criteria that your system must meet:

( 1) The product of the mean rise time and the frequency at which the system records an updated concentration must be at least 5, and the product of the mean fall time and the frequency at which the system records an updated concentration must be at least 5. This criteria makes no assumption regarding the frequency content of changes in emission concentrations during emission testing; therefore, it is valid for any testing.

( 2) The frequency at which the system records an updated concentration must be at least 5 Hz. This criteria assumes that the frequency content of significant changes in emission concentrations during emission testing do not exceed 1 Hz.

( 3) You may use other criteria if we approve the criteria in advance.

( 4) For PEMS, you do not have to meet this criteria if your PEMS meets the overall PEMS check in § 1065.920.

( d) Procedure. Use the following procedure to verify the response of a continuous gas analyzer system:

( 1) Instrument setup. Follow the analyzer system manufacturer's start up and operating instructions. Adjust the system as needed to optimize performance.

( 2) Equipment setup. Using minimal gas transfer line lengths between all connections, connect a zero air source to one inlet of a fast acting 3 way valve ( 2 inlets, 1 outlet). Using a gas divider, equally blend an NO CO CO 2 C 3 H 8 CH 4 ( balance N 2) span gas with a span gas of NO 2. Connect the gas divider outlet to the other inlet of the 3 way valve. Connect the valve outlet to an overflow at the gas analyzer system's probe or to an overflow fitting between the probe and transfer line to all the analyzers being verified.

( 3) Data collection. ( i) Switch the valve to flow zero gas.

( ii) Allow for stabilization, accounting for transport delays and the slowest instrument's full response.

( iii) Start recording data at the frequency used during emission testing. Each recorded value must be a unique updated concentration measured by the analyzer; you may not use interpolation to increase the number of recorded values.

( iv) Switch the valve to flow the blended span gases.

( v) Allow for transport delays and the slowest instrument's full response.

( vi) Repeat the steps in paragraphs ( d)( 3)( i) through ( v) of this section to record seven full cycles, ending with zero gas flowing to the analyzers.

( vii) Stop recording. 250 ( e) Performance evaluation. ( 1) If you selected to demonstrate compliance with paragraph ( c)( 2)( i) of this section, use the data from paragraph ( d)( 3) of this section to calculate the mean rise time, T 10 90, and mean fall time, T 90 10, for each of the analyzers. Multiply these times ( in seconds) by their respective recording frequencies in Hertz ( 1/ second). The value for each result must be at least 5. If the value is less than 5, increase the recording frequency or adjust the flows or design of the sampling system to increase the rise time and fall time as needed. You may also configure digital filters to increase rise and fall times.

( 2) If a measurement system fails the criterion in paragraph ( e)( 1) of this section, ensure that signals from the system are updated and recorded at a frequency of at least 5 Hz.

( 3) If a measurement system fails the criteria in paragraphs ( e)( 1) and ( 2) of this section, you may use the continuous analyzer system if the deficiency does not adversely affect your ability to show compliance with the applicable standards.

§ 1065.309 Continuous gas analyzer uniform response verification. ( a) Scope and frequency. If you use more than one continuous gas analyzer to quantify a gaseous constituent, you must perform this verification. For example, if you determine NMHC as the difference between continuous THC and CH4 measurements, you must perform this verification on your NMHC measurement system. As another example if you determine NO x as the sum of separate continuous measurements of NO and NO 2, you must perform this verification on your NO x measurement system. Also, you must perform this verification if you use one continuous analyzer to apply an interference compensation algorithm to another continuous gas analyzer. Perform this verification after initial installation or major maintenance. Also perform this verification if you reconfigure your system in a way that would change system response. For example, perform this verification if you add a significant volume to the transfer lines by increasing their length or by adding a filter; or if you change the frequency at which you sample and record gas analyzer concentrations.

( b) Measurement principles. This procedure verifies the time alignment and uniform response of combined continuous gas measurements.

( c) System requirements. Demonstrate that combined continuous concentration measurements have a uniform rise and fall during a simultaneous to a step change in both concentrations. During a system response to a rapid change in multiple gas concentrations, demonstrate that the t 50 times of all combined analyzers all occur at the same recorded second of data or between the same two recorded seconds of data.

( d) Procedure. Use the following procedure to verify the response of a continuous gas analyzer system:

( 1) Instrument setup. Follow the analyzer system manufacturer's start up and operating instructions. Adjust the system as needed to optimize performance.

( 2) Equipment setup. Using minimal gas transfer line lengths between all connections, connect a zero air source to the inlet of a 100

C heated line. Connect the heated line outlet to one inlet of a 100

C heated fast acting 3 way valve ( 2 inlets, 1 outlet). Using a gas divider, equally blend an NO CO CO 2 C 3 H 8 CH 4 ( balance N 2) span gas with a span gas of NO 2 ( balance N 2). Connect the gas divider outlet to the inlet of a 50

C heated line. Connect the heated line outlet to the inlet of a 50

C gas bubbler filled with distilled water. Connect the bubbler outlet to another heated line at 100

C. Connect the outlet of the 100

C line to the other inlet of the 3 way valve. Connect the valve outlet to an overflow at the gas analyzer system's probe or to an overflow fitting between the probe and transfer line to all the analyzers being verified. 251 ( 3) Data collection. ( i) Switch the valve to flow zero gas.

( ii) Allow for stabilization, accounting for transport delays and the slowest instrument's full response.

( iii) Start recording data at the frequency used during emission testing.

( iv) Switch the valve to flow span gas.

( v) Allow for transport delays and the slowest instrument's full response.

( vi) Repeat the steps in paragraphs ( d)( 3)( i) through ( v) of this section to record seven full cycles, ending with zero gas flowing to the analyzers.

( vii) Stop recording.

( e) Performance evaluations. Perform the following evaluations:

( 1) Uniform response evaluation. ( i) Calculate the mean rise time, t 10 90, mean fall time, t 90 10 for each analyzer.

( ii) Determine the maximum mean rise and fall times for the slowest responding analyzer in each combination of continuous analyzer signals that you use to determine a single emission concentration.

( iii) If the maximum rise time or fall time is greater than one second, verify that all other gas analyzers combined with it have mean rise and fall times of at least 75 % of that analyzer's response.

( iv) If any analyzer has shorter rise or fall times, disperse that signal so that it better matches the rise and fall times of the slowest signal with which it is combined. We recommend that you perform dispersion using SAE 2001 01 3536 ( incorporated by reference in § 1065.1010) as a guide.

( v) Repeat this verification after optimizing your systems to ensure that you dispersed signals correctly. If after repeated attempts at dispersing signals your system still fails this verification, you may use the continuous analyzer system if the deficiency does not adversely affect your ability to show compliance with the applicable standards.

( 2) Time alignment evaluation. ( i) After all signals are adjusted to meet the uniform response evaluation, determine the second at which   or the two seconds between which   each analyzer crossed the midpoint of its response, t 50. ( ii) Verify that all combined gas analyzer signals are time aligned such that all of their t 50 times occurred at the same second or between the same two seconds in the recorded data.

( iii) If your system fails to meet this criterion, you may change the time alignment of your system and retest the system completely. If after changing the time alignment of your system, some of the t 50 times still are not aligned, take corrective action by dispersing analyzer signals that have the shortest rise and fall times.

( iv) If some t 50 times are still not aligned after repeated attempts at dispersion and time alignment, you may use the continuous analyzer system if the deficiency does not adversely affect your ability to show compliance with the applicable standards.

MEASUREMENT OF ENGINE PARAMETERS AND AMBIENT CONDITIONS § 1065.310 Torque calibration. ( a) Scope and frequency. Calibrate all torque measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after major maintenance. 252 Use good engineering judgment to repeat the calibration. Follow the torque transducer manufacturer's instructions for linearizing your torque sensor's output. We recommend that you calibrate the torque measurement system with a reference force and a lever arm.

( b) Recommended procedure.

( 1) Reference force quantification. Use either a set of dead weights or a reference meter such as strain gage or a proving ring to quantify the reference force, NIST traceable within + 0.5 % uncertainty.

( 2) Lever arm length quantification. Quantify the lever arm length, NIST traceable within + 0.5 % uncertainty. The lever arm's length must be measured from the centerline of the dynamometer to the point at which the reference force is measured. The lever arm must be perpendicular to gravity ( i. e., horizontal), and it must be perpendicular to the dynamometer's rotational axis. Balance the lever arm's torque or quantify its net hanging torque, NIST traceable within + 1 % uncertainty, and account for it as part of the reference torque.

( b) Dead weight calibration. This technique applies a known force by hanging known weights at a known distance along a lever arm. Make sure the weights' lever arm is perpendicular to gravity ( i. e., horizontal) and perpendicular to the dynamometer's rotational axis. Apply at least six calibration weight combinations for each applicable torque measuring range, spacing the weight quantities about equally over the range. Oscillate or rotate the dynamometer during calibration to reduce frictional static hysteresis. Determine each weight's force by multiplying its NISTtraceable mass by the local acceleration of Earth's gravity ( using this equation: force = mass

acceleration). The local acceleration of gravity, a g , at your latitude, longitude, and elevation may be determined by entering position and elevation data into the U. S. National Oceanographic and Atmospheric Administration's surface gravity prediction website at http:// www. ngs. noaa. gov/ cgi bin/ grav_ pdx. prl. If this website is unavailable, you may use the equation in § 1065.630, which returns the local acceleration of gravity based on a given latitude. In this case, calculate the reference torque as the weights' reference force multiplied by the lever arm reference length ( using this equation: torque = force

lever arm length).

( c) Strain gage or proving ring calibration. This technique applies force either by hanging weights on a lever arm ( these weights and their lever arm length are not used) or by operating the dynamometer at different torques. Apply at least six force combinations for each applicable torque measuring range, spacing the force quantities about equally over the range. Oscillate or rotate the dynamometer during calibration to reduce frictional static hysteresis. In this case, the reference torque is determined by multiplying the reference meter force output by its effective lever arm length, which you measure from the point where the force measurement is made to the dynamometer's rotational axis. Make sure you measure this length perpendicular to gravity ( i. e., horizontal) and perpendicular to the dynamometer's rotational axis.

§ 1065.315 Pressure, temperature, and dewpoint calibration.

( a) Scope and frequency. Calibrate instruments for measuring pressure, temperature, and dewpoint upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration, as follows:

( 1) Pressure. We recommend temperature compensated, digital pneumatic, or deadweight pressure calibrators, with data logging capabilities to minimize transcription errors. We recommend using calibration reference quantities that are NIST traceable within 0.5 % uncertainty. 253 ( 2) Temperature. We recommend digital dry block or stirred liquid temperature calibrators, with datalogging capabilities to minimize transcription errors. We recommend using calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

( 3) Dewpoint. We recommend a minimum of three different temperature equilibrated and temperature monitored calibration salt solutions in containers that seal completely around the dewpoint sensor. We recommend using calibration reference quantities that are NISTtraceable within 0.5 % uncertainty.

( b) You may remove system components for off site calibration. We recommend specifying calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

FLOW RELATED MEASUREMENTS § 1065.320 Fuel flow calibration.

( a) Scope and frequency. Calibrate fuel flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration.

( b) You may also develop a procedure based on a chemical balance of carbon or oxygen in engine exhaust.

( c) You may remove system components for off site calibration. When installing a flow meter with an off site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

§ 1065.325 Intake flow calibration.

( a) Scope and frequency. Calibrate intake air flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration. We recommend using a calibration subsonic venturi, ultrasonic flow meter or laminar flow element. We recommend using calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

( b) You may remove system components for off site calibration. When installing a flow meter with an off site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

( c) If you use a subsonic venturi or ultrasonic flow meter for intake flow measurement, we recommend that you calibrate it as described in § 1065.340.

§ 1065.330 Exhaust flow calibration. ( a) Scope and frequency. Calibrate exhaust flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration. We recommend that you use a calibration subsonic venturi or ultrasonic flow meter and simulate exhaust temperatures by incorporating a heat exchanger between the calibration meter and the exhaust flow meter. If you can demonstrate that the flow meter to be calibrated is insensitive to exhaust temperatures, you may use other reference meters such as laminar flow elements, which are not commonly designed to withstand typical raw exhaust temperatures. We 254 recommend using calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

( b) You may remove system components for off site calibration. When installing a flow meter with an off site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST traceable within 0.5 % uncertainty.

( c) If you use a subsonic venturi or ultrasonic flow meter for raw exhaust flow measurement, we recommend that you calibrate it as described in § 1065.340.

§ 1065.340 Diluted exhaust flow ( CVS) calibration. ( a) Overview. This section describes how to calibrate flow meters for diluted exhaust constantvolume sampling ( CVS) systems.

( b) Scope and frequency. Perform this calibration while the flow meter is installed in its permanent position. Perform this calibration after you change any part of the flow configuration upstream or downstream of the flow meter that may affect the flow meter calibration. Perform this calibration upon initial CVS installation and whenever corrective action does not resolve a failure to meet the diluted exhaust flow verification ( i. e., propane check) in § 1065.341.

( c) Reference flow meter. Calibrate a CVS flow meter using a reference flow meter such as a subsonic venturi flow meter, a long radius ASME/ NIST flow nozzle, a smooth approach orifice, a laminar flow element, a set of critical flow venturis, or an ultrasonic flow meter. Use a reference flow meter that reports quantities that are NIST traceable within + 1 % uncertainty. Use this reference flow meter's response to flow as the reference value for CVS flow meter calibration.

( d) Configuration. Do not use an upstream screen or other restriction that could affect the flow ahead of the reference flow meter, unless the flow meter has been calibrated with such a restriction.

( e) PDP calibration. Calibrate a positive displacement pump ( PDP) to determine a flow versus PDP speed equation that accounts for flow leakage across sealing surfaces in the PDP as a function of PDP inlet pressure. Determine unique equation coefficients for each speed at which you operate the PDP. Calibrate a PDP flow meter as follows:

( 1) Connect the system as shown in Figure 1 of this section.

( 2) Leaks between the calibration flow meter and the PDP must be less than 0.3 % of the total flow at the lowest calibrated flow point; for example, at the highest restriction and lowest PDP speed point.

( 3) While the PDP operates, maintain a constant temperature at the PDP inlet within + 2 % of the mean absolute inlet temperature, . in T ( 4) Set the PDP speed to the first speed point at which you intend to calibrate.

( 5) Set the variable restrictor to its wide open position.

( 6) Operate the PDP for at least 3 min to stabilize the system. Continue operating the PDP and record the mean values of at least 30 seconds of sampled data of each of the following quantities:

( i) The mean flow rate of the reference flow meter, . This may include several ref n

measurements of different quantities, such as reference meter pressures and temperatures,

for calculating . ref n

( ii) The mean temperature at the PDP inlet, . in T 255 ( iii) The mean static absolute pressure at the PDP inlet, . in p ( iv) The mean static absolute pressure at the PDP outlet, . out p ( v) The mean PDP speed, . nPDP f ( 7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to the PDP, . in p ( 8) Repeat the steps in paragraphs ( e)( 6) and ( 7) of this section to record data at a minimum of six restrictor positions reflecting the full range of possible in use pressures at the PDP inlet.

( 9) Calibrate the PDP by using the collected data and the equations in § 1065.640.

( 10) Repeat the steps in paragraphs ( e)( 6) through ( 9) of this section for each speed at which you operate the PDP.

( 11) Use the equations in § 1065.642 to determine the PDP flow equation for emission testing.

( 12) Verify the calibration by performing a CVS verification ( i. e., propane check) as described in § 1065.341.

( 13) Do not use the PDP below the lowest inlet pressure tested during calibration.

( f) CFV calibration. Calibrate a critical flow venturi ( CFV) to verify its discharge coefficient, C d, at the lowest expected static differential pressure between the CFV inlet and outlet. Calibrate a CFV flow meter as follows:

( 1) Connect the system as shown in Figure 1 of this section.

( 2) Start the blower downstream of the CFV.

( 3) While the CFV operates, maintain a constant temperature at the CFV inlet within + 2 % of the mean absolute inlet temperature, . in T ( 4) Leaks between the calibration flow meter and the CFV must be less than 0.3 % of the total flow at the highest restriction.

( 5) Set the variable restrictor to its wide open position.

( 6) Operate the CFV for at least 3 min to stabilize the system. Continue operating the CFV and record the mean values of at least 30 seconds of sampled data of each of the following quantities:

( i) The mean flow rate of the reference flow meter, . This may include several ref n

measurements of different quantities, such as reference meter pressures and temperatures,

for calculating . ref n

( ii) Optionally, the mean dewpoint of the calibration air, . See § 1065.640 for dew T permissible assumptions.

( iii) The mean temperature at the venturi inlet, . in T ( iv) The mean static absolute pressure at the venturi inlet, . in p ( v) The mean static differential pressure between the CFV inlet and the CFV outlet, . CFV p

( 7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to the CFV, . in p 256 ( 8) Repeat the steps in paragraphs ( f)( 6) and ( 7) of this section to record mean data at a minimum of ten restrictor positions, such that you test the fullest practical range of CFV p   expected during testing. We do not require that you remove calibration components or CVS components to calibrate at the lowest possible restrictions.

( 9) Determine C d and the lowest allowable as described in § 1065.640. CFV p

( 10) Use C d to determine CFV flow during an emission test. Do not use the CFV below the lowest allowed , as determined in § 1065.640. CFV dew p T

( 11) Verify the calibration by performing a CVS verification ( i. e., propane check) as described in § 1065.341.

( 12) If your CVS is configured to operate more than one CFV at a time in parallel, calibrate your CVS by one of the following:

( i) Calibrate every combination of CFVs according to this section and § 1065.640. Refer to § 1065.642 for instructions on calculating flow rates for this option.

( ii) Calibrate each CFV according to this section and § 1065.640. Refer to § 1065.642 for instructions on calculating flow rates for this option.

( g) SSV calibration. Calibrate a subsonic venturi ( SSV) to determine its calibration coefficient, C d , for the expected range of inlet pressures. Calibrate an SSV flow meter as follows:

( 1) Connect the system as shown in Figure 1 of this section.

( 2) Start the blower downstream of the SSV.

( 3) Leaks between the calibration flow meter and the SSV must be less than 0.3 % of the total flow at the highest restriction.

( 4) While the SSV operates, maintain a constant temperature at the SSV inlet within + 2 % of the mean absolute inlet temperature, . in T ( 5) Set the variable restrictor or variable speed blower to a flow rate greater than the greatest flow rate expected during testing. You may not extrapolate flow rates beyond calibrated values, so we recommend that you make sure the Reynolds number, Re#, at the SSV throat at the greatest calibrated flow rate is greater than the maximum Re# expected during testing.

( 6) Operate the SSV for at least 3 min to stabilize the system. Continue operating the SSV and record the mean of at least 30 seconds of sampled data of each of the following quantities:

( i) The mean flow rate of the reference flow meter, . This may include several ref n

measurements of different quantities, such as reference meter pressures and temperatures,

for caculating . ref n

( ii) Optionally, the mean dewpoint of the calibration air, . See § 1065.640 for dew SSV T p   permissible assumptions.

( iii) The mean temperature at the venturi inlet, . in T ( iv) The mean static absolute pressure at the venturi inlet, . in p ( v) Static differential pressure between the static pressure at the venturi inlet and the static pressure at the venturi throat, . SSV p

( 7) Incrementally close the restrictor valve or decrease the blower speed to decrease the flow rate. 257 ( 8) Repeat the steps in paragraphs ( g)( 6) and ( 7) of this section to record data at a minimum of ten flow rates.

( 9) Determine a functional form of C d versus Re# by using the collected data and the equations in § 1065.640.

( 10) Verify the calibration by performing a CVS verification ( i. e., propane check) as described in § 1065.341 using the new C d versus Re# equation.

( 11) Use the SSV only between the minimum and maximum calibrated flow rates.

( 12) Use the equations in § 1065.642 to determine SSV flow during a test.

( h) Ultrasonic flow meter calibration. [ Reserved]

[ NOTE TO PRINTER   INSERT Figure 1 of § 1065.340 HERE] 258 § 1065.341 CVS and batch sampler verification ( propane check).

( a) A propane check serves as a CVS verification to determine if there is a discrepancy in measured values of diluted exhaust flow. A propane check also serves as a batch sampler verification to determine if there is a discrepancy in a batch sampling system that extracts a sample from a CVS, as described in paragraph ( g) of this section. Using good engineering judgment and safe practices, this check may be performed using a gas other than propane, such as CO 2 or CO. A failed propane check might indicate one or more problems that may require corrective action, as follows:

( 1) Incorrect analyzer calibration. Re calibrate, repair, or replace the FID analyzer.

( 2) Leaks. Inspect CVS tunnel, connections, fasteners, and HC sampling system, and repair or replace components.

( 3) Poor mixing. Perform the verification as described in paragraph ( b) of this section while traversing a sampling probe across the tunnel's diameter, vertically and horizontally. If the analyzer response indicates any deviation exceeding + 2 % of the mean measured concentration, consider operating the CVS at a higher flow rate or installing a mixing plate or orifice to improve mixing.

( 4) Hydrocarbon contamination in the sample system. Perform the hydrocarboncontamination verification as described in § 1065.520.

( 5) Change in CVS calibration. Perform an in situ calibration of the CVS flow meter as described in § 1065.340.

( 6) Other problems with the CVS or sampling verification hardware or software. Inspect the CVS system, CVS verification hardware, and software for discrepancies.

( b) A propane check uses either a reference mass or a reference flow rate of C 3 H 8 as a tracer gas in a CVS. Note that if you use a reference flow rate, account for any non ideal gas behavior of C 3 H 8 in the reference flow meter. Refer to § 1065.640 and § 1065.642, which describe how to calibrate and use certain flow meters. Do not use any ideal gas assumptions in § 1065.640 and § 1065.642. The propane check compares the calculated mass of injected C 3 H 8 using HC measurements and CVS flow rate measurements with the reference value.

( c) Prepare for the propane check as follows:

( 1) If you use a reference mass of C 3 H 8 instead of a reference flow rate, obtain a cylinder charged with C 3 H 8. Determine the reference cylinder's mass of C 3 H 8 within + 0.5 % of the amount of C 3 H 8 that you expect to use.

( 2) Select appropriate flow rates for the CVS and C 3 H 8. ( 3) Select a C 3 H 8 injection port in the CVS. Select the port location to be as close as practical to the location where you introduce engine exhaust into the CVS. Connect the C 3 H 8 cylinder to the injection system.

( 4) Operate and stabilize the CVS.

( 5) Preheat or precool any heat exchangers in the sampling system.

( 6) Allow heated and cooled components such as sample lines, filters, chillers, and pumps to stabilize at operating temperature.

( 7) You may purge the HC sampling system during stabilization.

( 8) If applicable, perform a vacuum side leak verification of the HC sampling system as described in § 1065.345.

( 9) You may also conduct any other calibrations or verifications on equipment or analyzers. 259 ( d) Zero, span, and verify contamination of the HC sampling system, as follows:

( 1) Select the lowest HC analyzer range that can measure the C 3 H 8 concentration expected for the CVS and C 3 H 8 flow rates.

( 2) Zero the HC analyzer using zero air introduced at the analyzer port.

( 3) Span the HC analyzer using C 3 H 8 span gas introduced at the analyzer port.

( 4) Overflow zero air at the HC probe or into a fitting between the HC probe and the transfer line.

( 5) Measure the stable HC concentration of the HC sampling system as overflow zero air flows. For batch HC measurement, fill the batch container ( such as a bag) and measure the HC overflow concentration.

( 6) If the overflow HC concentration exceeds 2 µ mol/ mol, do not proceed until contamination is eliminated. Determine the source of the contamination and take corrective action, such as cleaning the system or replacing contaminated portions.

( 7) When the overflow HC concentration does not exceed 2 µ mol/ mol, record this value as x HCpre and use it to correct for HC contamination as described in § 1065.660.

( e) Perform the propane check as follows:

( 1) For batch HC sampling, connect clean storage media, such as evacuated bags.

( 2) Operate HC measurement instruments according to the instrument manufacturer's instructions.

( 3) If you will correct for dilution air background concentrations of HC, measure and record background HC in the dilution air.

( 4) Zero any integrating devices.

( 5) Begin sampling, and start any flow integrators.

( 6) Release the contents of the C 3 H 8 reference cylinder at the rate you selected. If you use a reference flow rate of C 3 H 8, start integrating this flow rate.

( 7) Continue to release the cylinder's contents until at least enough C 3 H 8 has been released to ensure accurate quantification of the reference C 3 H 8 and the measured C 3 H 8. ( 8) Shut off the C 3 H 8 reference cylinder and continue sampling until you have accounted for time delays due to sample transport and analyzer response.

( 9) Stop sampling and stop any integrators.

( f) Perform post test procedure as follows:

( 1) If you used batch sampling, analyze batch samples as soon as practical.

( 2) After analyzing HC, correct for contamination and background.

( 3) Calculate total C 3 H 8 mass based on your CVS and HC data as described in § 1065.650 and § 1065.660, using the molar mass of C 3 H 8, M C3H8, instead the effective molar mass of HC, M HC. ( 4) If you use a reference mass, determine the cylinder's propane mass within + 0.5 % and determine the C 3 H 8 reference mass by subtracting the empty cylinder propane mass from the full cylinder propane mass.

( 5) Subtract the reference C 3 H 8 mass from the calculated mass. If this difference is within + 2.0 % of the reference mass, the CVS passes this verification. If not, take corrective action as described in paragraph ( a) of this section.

( g) Batch sampler verification. You may repeat the propane check to verify a batch sampler, such as a PM secondary dilution system. 260 ( 1) Configure the HC sampling system to extract a sample near the location of the batch sampler's storage media ( such as a PM filter). If the absolute pressure at this location is too low to extract an HC sample, you may sample HC from the batch sampler pump's exhaust. Use caution when sampling from pump exhaust because an otherwise acceptable pump leak downstream of a batch sampler flow meter will cause a false failure of the propane check.

( 2) Repeat the propane check described in this section, but sample HC from the batch sampler.

( 3) Calculate C 3 H 8 mass, taking into account any secondary dilution from the batch sampler.

( 4) Subtract the reference C 3 H 8 mass from the calculated mass. If this difference is within + 5 % of the reference mass, the batch sampler passes this verification. If not, take corrective action as described in paragraph ( a) of this section.

§ 1065.345 Vacuum side leak verification.

( a) Scope and frequency. Upon initial sampling system installation, after major maintenance, and before each test according to subpart F of this part for laboratory tests and according to subpart J for field tests, verify that there are no significant vacuum side leaks using one of the leak tests described in this section.

( b) Measurement principles. A leak may be detected either by measuring a small amount of flow when there should be zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the vacuum side of a sampling system.

( c) Low flow leak test. Test a sampling system for low flow leaks as follows:

( 1) Seal the probe end of the system by taking one of the following steps:

( i) Cap or plug the end of the sample probe.

( ii) Disconnect the transfer line at the probe and cap or plug the transfer line.

( iii) Close a leak tight valve in line between a probe and transfer line.

( 2) Operate all vacuum pumps. After stabilizing, verify that the flow through the vacuum side of the sampling system is less than 0.5 % of the system's normal in use flow rate. You may estimate typical analyzer and bypass flows as an approximation of the system's normal in use flow rate.

( d) Dilution of span gas leak test. Test any analyzer, other than a FID, for dilution of span gas as follows, noting that this configuration requires an overflow span gas system:

( 1) Prepare a gas analyzer as you would for emission testing.

( 2) Supply span gas to the analyzer port and verify that it measures the span gas concentration within its expected measurement accuracy and repeatability.

( 3) Route overflow span gas to one of the following locations in the sampling system:

( i) The end of the sample probe.

( ii) Disconnect the transfer line at the probe connection, and overflow the span gas at the open end of the transfer line.

( iii) A three way valve installed in line between a probe and its transfer line, such as a system overflow zero and span port.

( 3) Verify that the measured overflow span gas concentration is within the measurement accuracy and repeatability of the analyzer. A measured value lower than expected indicates a leak, but a value higher than expected may indicate a problem with the span gas or the analyzer itself. A measured value higher than expected does not indicate a leak. 261 CO AND CO 2 MEASUREMENTS § 1065.350 H2O interference verification for CO2 NDIR analyzers.

( a) Scope and frequency. If you measure CO 2 using an NDIR analyzer, verify the amount of H 2 O interference after initial analyzer installation and after major maintenance.

( b) Measurement principles. H 2 O can interfere with an NDIR analyzer's response to CO 2. If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously conduct these other measurements to test the compensation algorithms during the analyzer interference verification.

( c) System requirements. A CO 2 NDIR analyzer must have an H 2 O interference that is within + 2 % of the flow weighted mean CO 2 concentration expected at the standard, though we strongly recommend a lower interference that is within + 1 %.

( d) Procedure. Perform the interference verification as follows:

( 1) Start, operate, zero, and span the CO 2 NDIR analyzer as you would before an emission test.

( 2) Create a water saturated test gas by bubbling zero air that meets the specifications in § 1065.750 through distilled water in a sealed vessel at ( 25 + 10)  C.

( 3) Introduce the water saturated test gas upstream of any sample dryer, if one is used during testing.

( 4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.

( 5) While the analyzer measures the sample's concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of this data. The analyzer meets the interference verification if this value is within + 2 % of the flow weighted mean concentration of CO 2 expected at the standard.

( e) Exceptions. The following exceptions apply:

( 1) You may omit this verification if you can show by engineering analysis that for your CO 2 sampling system and your emission calculation procedures, the H 2 O interference for your CO 2 NDIR analyzer always affects your brake specific emission results within + 0.5 % of each of the applicable standards.

( 2) You may use a CO 2 NDIR analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.

§ 1065.355 H2O and CO2 interference verification for CO NDIR analyzers. ( a) Scope and frequency. If you measure CO using an NDIR analyzer, verify the amount of H 2 O and CO 2 interference after initial analyzer installation and after major maintenance.

( b) Measurement principles. H 2 O and CO 2 can positively interfere with an NDIR analyzer by causing a response similar to CO. If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously conduct these other measurements to test the compensation algorithms during the analyzer interference verification.

( c) System requirements. A CO NDIR analyzer must have combined H 2 O and CO 2 interference that is within + 2 % of the flow weighted mean concentration of CO expected at the standard, though we strongly recommend a lower interference that is within + 1 %. 262 ( d) Procedure. Perform the interference verification as follows:

( 1) Start, operate, zero, and span the CO NDIR analyzer as you would before an emission test.

( 2) Create a water saturated CO 2 test gas by bubbling a CO 2 span gas through distilled water in a sealed vessel at ( 25 + 10)  C.

( 3) Introduce the water saturated CO 2 test gas upstream of any sample dryer, if one is used during testing.

( 4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.

( 5) While the analyzer measures the sample's concentration, record its output for 30 seconds. Calculate the arithmetic mean of this data.

( 6) Multiply this mean value by the ratio of expected CO 2 to span gas CO 2 concentration. In other words, estimate the flow weighted mean dry concentration of CO 2 expected during testing, and then divide this value by the concentration of CO 2 in the span gas used for this verification. Then multiply this ratio by the mean value recorded during this verification.

( 7) The analyzer meets the interference verification if the result of paragraph ( d)( 6) of this section is within + 2 % of the flow weighted mean concentration of CO expected at the standard.

( e) Exceptions. The following exceptions apply:

( 1) You may omit this verification if you can show by engineering analysis that for your CO sampling system and your emission calculations procedures, the the combined CO 2 and H 2 O interference for your CO NDIR analyzer always affects your brake specific CO emission results within + 0.5 % of the applicable CO standard.

( 2) You may use a CO NDIR analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.

HYDROCARBON MEASUREMENTS § 1065.360 FID optimization and verification.

( a) Scope and frequency. For all FID analyzers perform the following steps:

( 1) Calibrate a FID upon initial installation. Repeat the calibration as needed using good engineering judgment.

( 2) Optimize a FID's response to various hydrocarbons after initial analyzer installation and after major maintenance.

( 3) Determine a FID's methane ( CH 4) response factor after initial analyzer installation and after major maintenance.

( 4) Verify methane ( CH 4) response within 185 days before testing.

( b) Calibration. Use good engineering judgment to develop a calibration procedure, such as one based on the FID analyzer manufacturer's instructions and recommended frequency for calibrating the FID. Alternately, you may remove system components for off site calibration. Calibrate using C 3 H 8 calibration gases that meet the specifications of § 1065.750. We recommend FID analyzer zero and span gases that contain approximately the flow weighted mean concentration of O 2 expected during testing. If you use a FID to measure methane ( CH 4) downstream of a nonmethane cutter, you may calibrate that FID using CH 4 calibration gases with 263 the cutter. Regardless of the calibration gas composition, calibrate on a carbon number basis of one ( C 1). For example, if you use a C 3 H 8 span gas of concentration 200 µ mol/ mol, span the FID to respond with a value of 600 µ mol/ mol.

( c) FID response optimization. Use good engineering judgment for initial instrument start up and basic operating adjustment using FID fuel and zero air. Heated FIDs must be within their required operating temperature ranges. Optimize FID response at the most common analyzer range expected during emission testing. Optimization involves adjusting flows and pressures of FID fuel, burner air, and sample to minimize response variations to various hydrocarbon species in the exhaust. Use good engineering judgment to trade off peak FID response to propane calibration gases to achieve minimal response variations to different hydrocarbon species. For an example of trading off response to propane for relative responses to other hydrocarbon species, see Society of Automotive Engineers ( SAE) Paper No. 770141 ( incorporated by reference in § 1065.1010). Determine the optimum flow rates for FID fuel, burner air, and sample and record them for future reference.

( d) CH 4 response factor determination. Since FID analyzers generally have a different response to CH 4 versus C 3 H 8, determine each FID analyzer's CH 4 response factor, RF CH4, after FID optimization. Use the most recent RF CH4 measured according to this section in the calculations for HC determination described in § 1065.660 to compensate for CH 4 response. Determine RF CH4 as follows, noting that you do not determine RF CH4 for FIDs that are calibrated and spanned using CH 4 with a nonmethane cutter:

( 1) Select a C 3 H 8 span gas that meets the specifications of § 1065.750. Record the C 3 H 8 concentration of the gas.

( 2) Select a CH 4 span gas that meets the specifications of § 1065.750. Record the CH 4 concentration of the gas.

( 3) Start and operate the FID analyzer according to the manufacturer's instructions.

( 4) Confirm that the FID analyzer has been calibrated using C 3 H 8. Calibrate on a carbon number basis of one ( C 1). For example, if you use a C 3 H 8 span gas of concentration 200 µ mol/ mol, span the FID to respond with a value of 600 µ mol/ mol.

( 5) Zero the FID with a zero gas that you use for emission testing.

( 6) Span the FID with the C 3 H 8 span gas that you selected under paragraph ( d)( 1) of this section.

( 7) Introduce at the sample port of the FID analyzer, the CH 4 span gas that you selected under paragraph ( d)( 2) of this section.

( 8) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the analyzer and to account for its response.

( 9) While the analyzer measures the CH 4 concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of these values.

( 10) Divide the mean measured concentration by the recorded span concentration of the CH 4 calibration gas. The result is the FID analyzer's response factor for CH 4, RF CH4. ( e) FID methane ( CH 4) response verification. If the value of RF CH4 from paragraph ( d) of this section is within + 5.0 % of its most recent previously determined value, the FID passes the methane response verification. For example, if the most recent previous value for RFCH4 was 1.05 and it changed by + 0.05 to become 1.10 or it changed by  0.05 to become 1.00, either case would be acceptable because + 4.8 % is less than + 5.0 %.

( 1) Verify that the pressures and flow rates of FID fuel, burner air, and sample are each within + 0.5 % of their most recent previously recorded values, as described in paragraph ( c) of this 264 section. You may adjust these flow rates as necessary. Determine a new RF CH4 as described in paragraph ( d) of this section.

( 2) If RF CH4 is still not within + 5.0 % of its most recently determined value after adjusting flow rates, re optimize the FID response as described in paragraph ( c) of this section.

( 3) Determine a new RF CH4 as described in paragraph ( d) of this section. Use this new value of RF CH4 in the calculations for HC determination, as described in § 1065.660.

§ 1065.362 Non stoichiometric raw exhaust FID O2 interference verification. ( a) Scope and frequency. If you use FID analyzers for raw exhaust measurements from engines that operate in a non stoichiometric mode of combustion ( e. g., compression ignition, lean burn), verify the amount of FID O 2 interference upon initial installation and after major maintenance.

( b) Measurement principles. Changes in O 2 concentration in raw exhaust can affect FID response by changing FID flame temperature. Optimize FID fuel, burner air, and sample flow to meet this verification. Verify FID performance with the compensation algorithms for FID O 2 interference that you have active during an emission test.

( c) System requirements. Any FID analyzer used during testing must meet the FID O 2 interference verification according to the procedure in this section.

( d) Procedure. Determine FID O 2 interference as follows:

( 1) Select two span reference gases that meet the specifications in § 1065.750 and contain C 3 H 8 near 100% of span for HC. You may use CH 4 span reference gases for FIDs calibrated on CH 4 with a nonmethane cutter. Select the two balance gas concentrations such that the concentrations of O 2 and N 2 represent the minimum and maximum O 2 concentrations expected during testing.

( 2) Confirm that the FID analyzer meets all the specifications of § 1065.360.

( 3) Start and operate the FID analyzer as you would before an emission test. Regardless of the FID burner's air source during testing, use zero air as the FID burner's air source for this verification.

( 4) Zero the FID analyzer using the zero gas used during emission testing.

( 5) Span the FID analyzer using the span gas used during emission testing.

( 6) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of sampled data is within + 0.5 % of the span reference value used in paragraph ( d)( 5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph ( d)( 4) of this section.

( 7) Check the analyzer response using the span gas that has the minimum concentration of O 2 expected during testing. Record the mean response of 30 seconds of stabilized sample data as x O2minHC. ( 8) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of stabilized sample data is within + 0.5 % of the span reference value used in paragraph ( d)( 5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph ( d)( 4) of this section.

( 9) Check the analyzer response using the span gas that has the maximum concentration of O 2 expected during testing. Record the mean response of 30 seconds of stabilized sample data as x O2maxHC. ( 10) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of stabilized sample data is within + 0.5 % of 265 the span reference value used in paragraph ( d)( 5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph ( d)( 4) of this section.

( 11) Calculate the percent difference between x O2maxHC and its reference gas concentration. Calculate the percent difference between x O2minHC and its reference gas concentration. Determine the maximum percent difference of the two. This is the O 2 interference.

( 12) If the O 2 interference is within + 1.5 %, then the FID passes the O 2 interference check; otherwise perform one or more of the following to address the deficiency:

( i) Select zero and span gases for emission testing that contain higher or lower O 2 concentrations.

( ii) Adjust FID burner air, fuel, and sample flow rates. Note that if you adjust these flow rates to meet the O 2 interference verification, you must re verify with the adjusted flow rates that the FID meets the CH 4 response factor verification according to § 1065.360.

( iii) Repair or replace the FID.

( iv) Demonstrate that the deficiency does not adversely affect your ability to demonstrate compliance with the applicable emission standards.

§ 1065.365 Nonmethane cutter penetration fractions. ( a) Scope and frequency. If you use a FID analyzer and a nonmethane cutter ( NMC) to measure methane ( CH 4), determine the nonmethane cutter's penetration fractions of methane, PF CH4, and ethane, PF C2H6. Perform this verification after installing the nonmethane cutter. Repeat this verification within 185 days of testing to verify that the catalytic activity of the cutter has not deteriorated. Note that because nonmethane cutters can deteriorate rapidly and without warning if they are operated outside of certain ranges of gas concentrations and outside of certain temperature ranges, good engineering judgment may dictate that you determine a nonmethane cutter's penetration fractions more frequently.

( b) Measurement principles. A nonmethane cutter is a heated catalyst that removes nonmethane hydrocarbons from the exhaust stream before the FID analyzer measures the remaining hydrocarbon concentration. An ideal nonmethane cutter would have PF CH4 of 1.000, and the penetration fraction for all other hydrocarbons would be 0.000, as represented by PF C2H6. The emission calculations in § 1065.660 use this section's measured values of PF CH4 and PF C2H6 to account for less than ideal NMC performance.

( c) System requirements. We do not limit NMC penetration fractions to a certain range. However, we recommend that you optimize a nonmethane cutter by adjusting its temperature to achieve PF CH4 > 0.95 and PF C2H6 < 0.02 as determined by paragraphs ( d) and ( e) of this section, as applicable. If we use a nonmethane cutter for testing, it will meet this recommendation. If adjusting NMC temperature does not result in achieving both of these specifications simultaneously, we recommend that you replace the catalyst material. Use the most recently determined penetration values from this section to calculate HC emissions according to § 1065.660 and § 1065.665 as applicable.

( d) Procedure for a FID calibrated with the NMC. If your FID arrangement is such that a FID is always calibrated to measure CH 4 with the NMC, then span that FID with the NMC cutter using a CH 4 span gas, set that FID's CH 4 penetration fraction, PF CH4, equal to 1.0 for all emission calculations, and determine its ethane ( C 2 H 6) penetration fraction, PF C2H6. as follows:

( 1) Select a CH 4 gas mixture and a C 2 H 6 analytical gas mixture and ensure that both mixtures meet the specifications of § 1065.750. Select a CH 4 concentration that you would use for spanning the FID during emission testing and select a C 2 H 6 concentration that is typical of the 266 peak NMHC concentration expected at the hydrocarbon standard or equal to THC analyzer's span value.

( 2) Start, operate, and optimize the nonmethane cutter according to the manufacturer's instructions, including any temperature optimization.

( 3) Confirm that the FID analyzer meets all the specifications of § 1065.360.

( 4) Start and operate the FID analyzer according to the manufacturer's instructions.

( 5) Zero and span the FID with the cutter and use CH 4 span gas to span the FID with the cutter. Note that you must span the FID on a C 1 basis. For example, if your span gas has a CH 4 reference value of 100 µ mol/ mol, the correct FID response to that span gas is 100 µ mol/ mol because there is one carbon atom per CH 4 molecule.

( 6) Introduce the C 2 H 6 analytical gas mixture upstream of the nonmethane cutter.

( 7) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the nonmethane cutter and to account for the analyzer's response.

( 8) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of these data points.

( 9) Divide the mean by the reference value of C 2 H 6, converted to a C 1 basis. The result is the C 2 H 6 penetration fraction, PF C2H6. Use this penetration fraction and the CH 4 penetration fraction, which is set equal to 1.0, in emission calculations according to § 1065.660 or § 1065.665, as applicable.

( e) Procedure for a FID calibrated by bypassing the NMC. If you use a FID with an NMC that is calibrated by bypassing the NMC, determine penetration fractions as follows:

( 1) Select CH 4 and C 2 H 6 analytical gas mixtures that meet the specifications of § 1065.750 with the CH 4 concentration typical of its peak concentration expected at the hydrocarbon standard and the C 2 H 6 concentration typical of the peak total hydrocarbon ( THC) concentration expected at the hydrocarbon standard or the THC analyzer span value.

( 2) Start and operate the nonmethane cutter according to the manufacturer's instructions, including any temperature optimization.

( 3) Confirm that the FID analyzer meets all the specifications of § 1065.360.

( 4) Start and operate the FID analyzer according to the manufacturer's instructions.

( 5) Zero and span the FID as you would during emission testing. Span the FID by bypassing the cutter and by using C 3 H 8 span gas to span the FID. Note that you must span the FID on a C 1 basis. For example, if your span gas has a propane reference value of 100 µ mol/ mol, the correct FID response to that span gas is 300 µ mol/ mol because there are three carbon atoms per C 3 H 8 molecule.

( 6) Introduce the C 2 H 6 analytical gas mixture upstream of the nonmethane cutter.

( 7) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the nonmethane cutter and to account for the analyzer's response.

( 8) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of these data points.

( 9) Reroute the flow path to bypass the nonmethane cutter, introduce the C 2 H 6 analytical gas mixture to the bypass, and repeat the steps in paragraphs ( e)( 7) through ( 8) of this section.

( 10) Divide the mean C 2 H 6 concentration measured through the nonmethane cutter by the mean concentration measured after bypassing the nonmethane cutter. The result is the C 2 H 6 penetration fraction, PF C2H6. Use this penetration fraction according to § 1065.660 or § 1065.665, as applicable. 267 ( 12) Repeat the steps in paragraphs ( e)( 6) through ( 10) of this section, but with the CH 4 analytical gas mixture instead of C 2 H 6. The result will be the CH 4 penetration fraction, PF CH4. Use this penetration fraction according to § 1065.660 or § 1065.665, as applicable.

NO x MEASUREMENTS § 1065.370 CLD CO2 and H2O quench verification. ( a) Scope and frequency. If you use a CLD analyzer to measure NO x, verify the amount of H 2 O and CO 2 quench after installing the CLD analyzer and after major maintenance.

( b) Measurement principles. H 2 O and CO 2 can negatively interfere with a CLD's NO x response by collisional quenching, which inhibits the chemiluminescent reaction that a CLD utilizes to detect NO x. The calculations in § 1065.672 for H 2 O quench account for the water vapor in humidified NO span gas. The procedure and the calculations scale the quench results to the water vapor and CO 2 concentrations expected during testing. If the CLD analyzer uses quench compensation algorithms that utilize H 2 O and/ or CO 2 measurement instruments, use these instruments to measure H 2 O and/ or CO 2 and evaluate quench with the compensation algorithms applied.

( c) System requirements. A CLD analyzer must have a combined H 2 O and CO 2 quench of + 2 % or less, though we strongly recommend a quench of + 1 % or less. Combined quench is the sum of the CO 2 quench determined as described in paragraph ( d) of this section, plus the H 2 O quench determined in paragraph ( e) of this section.

( d) CO 2 quench verification procedure. Use the following method to determine CO 2 quench, or use good engineering judgment to develop a different protocol:

( 1) Use PTFE tubing to make necessary connections.

( 2) Connect a pressure regulated CO 2 span gas to one of the inlets of a three way valve made of 300 series stainless steel. Use a CO 2 span gas that meets the specifications of § 1065.750 and attempt to use a concentration that is approximately twice the maximum CO 2 concentration expected to enter the CLD sample port during testing, if available.

( 3) Connect a pressure regulated purified N 2 gas to the valve's other inlet. Use a purified N 2 gas that meets the specifications of § 1065.750.

( 4) Connect the valve's single outlet to the balance gas port of a gas divider that meets the specifications in § 1065.248.

( 5) Connect a pressure regulated NO span gas to the span port of the gas divider. Use an NO span gas that meets the specifications of § 1065.750. Attempt to use an NO concentration that is approximately twice the maximum NO concentration expected during testing, if available.

( 6) Configure the gas divider such that nearly equal amounts of the span gas and balance gas are blended with each other. Apply viscosity corrections as necessary to appropriately ensure correct gas division.

( 7) While flowing balance and span gases through the gas divider, stabilize the CO 2 concentration downstream of the gas divider and measure the CO 2 concentration with an NDIR analyzer that has been prepared for emission testing. Record this concentration, x CO2meas, and use it in the quench verification calculations in § 1065.675.

( 8) Measure the NO concentration downstream of the gas divider. If the CLD has an operating mode in which it detects NO only, as opposed to total NO x, operate the CLD in the 268 NO only operating mode. Record this concentration, x NO, CO2, and use it in the quench verification calculations in § 1065.675.

( 9) Switch the three way valve so 100 % purified N 2 flows to the gas divider's balance port inlet. Monitor the CO 2 at the gas divider's outlet until its concentration stabilizes at zero.

( 10) Measure NO concentration at the gas divider's outlet. Record this value, x NO, N2, and use it in the quench verification calculations in § 1065.675.

( 11) Use the values recorded according to this paragraph ( d) of this section and paragraph ( e) of this section to calculate quench as described in § 1065.675.

( e) H 2 O quench verification procedure. Use the following method to determine H 2 O quench, or use good engineering judgment to develop a different protocol:

( 1) Use PTFE tubing to make necessary connections.

( 2) If the CLD has an operating mode in which it detects NO only, as opposed to total NO x, operate the CLD in the NO only operating mode.

( 3) Measure an NO calibration span gas that meets the specifications of § 1065.750 and is near the maximum concentration expected during testing. Record this concentration, x NOdry. ( 4) Humidify the gas by bubbling it through distilled water in a sealed vessel. We recommend that you humidify the gas to the highest sample dewpoint that you estimate during emission sampling. Regardless of the humidity during this test, the quench verification calculations in § 1065.675 scale the recorded quench to the highest dewpoint that you expect entering the CLD sample port during emission sampling.

( 5) If you do not use any sample dryer for NO x during emissions testing, record the vessel water temperature as T dew, and its pressure as p total and use these values according to § 1065.645 to calculate the amount of water entering the CLD sample port, x H2Omeas. If you do use a sample dryer for NO x during emissions testing, measure the humidity of the sample just upstream of the CLD sample port and use the measured humidity according to § 1065.645 to calculate the amount of water entering the CLD sample port, x H2Omeas. ( 6) To prevent subsequent condensation, make sure that any humidified sample will not be exposed to temperatures lower than T dew during transport from the sealed vessel's outlet to the CLD. We recommend using heated transfer lines.

( 7) Introduce the humidified sample upstream of any sample dryer, if one is used.

( 8) Use the CLD to measure the NO concentration of the humidified span gas and record this value, x NOwet. ( 9) Use the recorded values from this paragraph ( e) to calculate the quench as described in § 1065.675.

( 10) Use the values recorded according to this paragraph ( e) of this section and paragraph ( d) of this section to calculate quench as described in § 1065.675.

( f) Corrective action. If the sum of the H 2 O quench plus the CO 2 quench is not within + 2 %, take corrective action by repairing or replacing the analyzer. Before using a CLD for emission testing, demonstrate that the corrective action resulted in a value within + 2 % combined quench.

( g) Exceptions. The following exceptions apply:

( 1) You may omit this verification if you can show by engineering analysis that for your NO x sampling system and your emission calculations procedures, the the combined CO 2 and H 2 O interference for your NO x CLD analyzer always affects your brake specific NO x emission results within no more than + 1.0 % of the applicable NO x standard. 269 ( 2) You may use a NO x CLD analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.

§ 1065.372 NDUV analyzer HC and H2O interference verification.

( a) Scope and frequency. If you measure NO x using an NDUV analyzer, verify the amount of H 2 O and hydrocarbon interference after initial analyzer installation and after major maintenance.

( b) Measurement principles. Hydrocarbons and H 2 O can positively interfere with an NDUV analyzer by causing a response similar to NO x. If the NDUV analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, simultaneously conduct such measurements to test the algorithms during the analyzer interference verification.

( c) System requirements. A NO x NDUV analyzer must have combined H 2 O and HC interference within + 2 % of the flow weighted mean concentration of NO x expected at the standard, though we strongly recommend keeping interference within + 1 %.

( d) Procedure. Perform the interference verification as follows:

( 1) Start, operate, zero, and span the NO x NDUV analyzer according to the instrument manufacturer's instructions.

( 2) We recommend that you extract engine exhaust to perform this verification. Use a CLD that meets the specifications of subpart C of this part to quantify NO x in the exhaust. Use the CLD response as the reference value. Also measure HC in the exhaust with a FID analyzer that meets the specifications of subpart C of this part. Use the FID response as the reference hydrocarbon value.

( 3) Upstream of any sample dryer, if one is used during testing, introduce the engine exhaust to the NDUV analyzer.

( 4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.

( 5) While all analyzers measure the sample's concentration, record 30 seconds of sampled data, and calculate the arithmetic means for the three analyzers.

( 6) Subtract the CLD mean from the NDUV mean.

( 7) Multiply this difference by the ratio of the flow weighted mean HC concentration expected at the standard to the HC concentration measured during the verification. The analyzer meets the interference verification of this section if this result is within + 2 % of the HC concentration expected at the standard.

( e) Exceptions. The following exceptions apply:

( 1) You may omit this verification if you can show by engineering analysis that for your NO x sampling system and your emission calculations procedures, the the combined HC and H 2 O interference for your NO x NDUV analyzer always affects your brake specific NO x emission results by less than 0.5 % of the applicable NO x standard.

( 2) You may use a NO x NDUV analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards. 270 § 1065.376 Chiller NO2 penetration. ( a) Scope and frequency. If you use a chiller to dry a sample upstream of a NO x measurement instrument, but you don't use an NO 2 to NO converter upstream of the chiller, you must perform this verification for chller NO 2 penetration. Perform this verification after initial installation and after major maintenance.

( b) Measurement principles. A chiller removes water, which can otherwise interfere with a NO x measurement. However, liquid water in an improperly designed chiller can remove NO 2 from the sample. If a chiller is used without an NO 2 to NO converter upstream, it could therefore remove NO 2 from the sample prior NO x measurement.

( c) System requirements. A chiller must allow for measuring at least 95 % of the total NO 2 at the maximum expected concentration of NO 2. ( d) Procedure. Use the following procedure to verify chiller performance:

( 1) Instrument setup. Follow the analyzer and chiller manufacturers' start up and operating instructions. Adjust the analyzer and chiller as needed to optimize performance.

( 2) Equipment setup. Connect an ozonator's inlet to a zero air or oxygen source and connect its outlet to one port of a three way tee fitting. Connect an NO span gas to another port of the tee. Connect a heated line at 100  C to the last port, and connect a heated three way tee to the other end of the line. Connect a dewpoint generator, set at a dewpoint of 50  C, to one end of a heated line at 100  C. Connect the other end of the line to the heated tee and connect a third 100  C heated line to the chiller inlet. Provide an overflow vent line at the chiller inlet.

( 3) Adjustments. For the following adjustment steps, set the analyzer to measure only NO ( i. e., NO mode), or only read the NO channel of the analyzer:

( i) With the dewpoint generator and the ozonator off, adjust the NO and zero gas flows so the NO concentration at the analyzer is at least two times the peak total NO x concentration expected during testing at the standard. Verify that gas is flowing out of the overflow vent line.

( ii) Turn on the dewpoint generator and adjust its flow so the NO concentration at the analyzer is at least at the peak total NO x concentration expected during testing at the standard. Verify that gas is flowing out of the overflow vent line.

( iii) Turn on the ozonator and adjust the ozonator so the NO concentration measured by the analyzer decreases by the same amount as the maximum concentration of NO 2 expected during testing. This ensures that the ozonator is generating NO 2 at the maximum concentration expected during testing.

( 4) Data collection. Maintain the ozonator adjustment in paragraph ( d)( 3) of this section, and keep the NO x analyzer in the NO only mode or only read the NO channel of the analyzer.

( i) Allow for stabilization, accounting only for transport delays and instrument response.

( ii) Calculate the mean of 30 seconds of sampled data from the analyzer and record this value as NO ref. ( iii) Switch the analyzer to the total NO x mode, ( that is, sum the NO and NO 2 channels of the analyzer) and allow for stabilization, accounting only for transport delays and instrument response.

( iv) Calculate the mean of 30 seconds of sampled data from the analyzer and record this value as NOx meas. 271 ( iii) Turn off the ozonator and allow for stabilization, accounting only for transport delays and instrument response.

( iv) Calculate the mean of 30 seconds of sampled data from the analyzer and record this value as NO xref. ( 5) Performance evaluation. Divide the quantity of ( NO xmeas  NO ref ) by the quantity of ( NO xref  NO ref). If the result is less than 95 %, repair or replace the chiller.

( e) Exceptions. The following exceptions apply:

( 1) You may omit this verification if you can show by engineering analysis that for your NO x sampling system and your emission calculations procedures, the the chiller always affects your brake specific NO x emission results by less than 0.5 % of the applicable NO x standard.

( 2) You may use a chiller that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.

§ 1065.378 NO2 to NO converter conversion verification.

( a) Scope and frequency. If you use an analyzer that measures only NO to determine NO x, you must use an NO 2 to NO converter upstream of the analyzer. Perform this verification after installing the converter, after major maintenance and within 35 days before an emission test. This verification must be repeated at this frequency to verify that the catalytic activity of the NO 2 to NO converter has not deteriorated.

( b) Measurement principles. An NO 2 to NO converter allows an analyzer that measures only NO to determine total NO x by converting the NO 2 in exhaust to NO.

( c) System requirements. An NO 2 to NO converter must allow for measuring at least 95 % of the total NO 2 at the maximum expected concentration of NO 2. ( d) Procedure. Use the following procedure to verify the performance of a NO 2 to NO converter:

( 1) Instrument setup. Follow the analyzer and NO 2 to NO converter manufacturers' start up and operating instructions. Adjust the analyzer and converter as needed to optimize performance.

( 2) Equipment setup. Connect an ozonator's inlet to a zero air or oxygen source and connect its outlet to one port of a 4 way cross fitting. Connect an NO span gas to another port. Connect the NO 2 to NO converter inlet to another port, and connect an overflow vent line to the last port.

( 3) Adjustments. Take the following steps to make adjustments:

( i) With the NO 2 to NO converter in the bypass mode ( i. e., NO mode) and the ozonator off, adjust the NO and zero gas flows so the NO concentration at the analyzer is at the peak total NO x concentration expected during testing. Verify that gas is flowing out of the overflow vent.

( ii) With the NO 2 to NO converter still in the bypass mode, turn on the ozonator and adjust the ozonator so the NO concentration measured by the analyzer decreases by the same amount as maximum concentration of NO 2 expected during testing. This ensures that the ozonator is generating NO 2 at the maximum concentration expected during testing.

( 4) Data collection. Maintain the ozonator adjustment in paragraph ( d)( 3) of this section, and keep the NO x analyzer in the NO only mode ( i. e., bypass the NO 2 to NO converter).

( i) Allow for stabilization, accounting only for transport delays and instrument response. 272 ( ii) Calculate the mean of 30 seconds of sampled data from the analyzer and record this value as NO ref. ( iii) Switch the analyzer to the total NO x mode ( that is, sample with the NO 2 to NO converter) and allow for stabilization, accounting only for transport delays and instrument response.