(1) Instrument setup.  Follow the analyzer manufacturer's start-up and operating instructions.  Adjust the measurement system as needed to optimize performance.  Run this verification with the analyzer operating in the same manner you will use for emission testing.  If the analyzer shares its sampling system with other analyzers, and if gas flow to the other analyzers will affect the system response time, then start up and operate the other analyzers while running this verification test.  You may run this verification test on multiple analyzers sharing the same sampling system at the same time.  If you use any analog or real-time digital filters during emission testing, you must operate those filters in the same manner during this verification.
(2) Equipment setup.  We recommend using minimal lengths of gas transfer lines between all connections and fast-acting three-way valves (2 inlets, 1 outlet) to control the flow of zero and blended span gases to the sample system's probe inlet or a tee near the outlet of the probe.  If you inject the gas at a tee near the outlet of the probe, you may correct the transformation time, t50, for an estimate of the transport time from the probe inlet to the tee.  Normally the gas flow rate is higher than the sample flow rate and the excess is overflowed out the inlet of the probe.  If the gas flow rate is lower than the sample flow rate, the gas concentrations must be adjusted to account for the dilution from ambient air drawn into the probe.  We recommend you use the final, stabilized analyzer reading as the final gas concentration.  Select span gases for the species being measured.  You may use binary or multi-gas span gases.  You may use a gas blending or mixing device to blend span gases.  A gas blending or mixing device is recommended when blending span gases diluted in N2 with span gases diluted in air.  You may use a multi-gas span gas, such as NO-CO-CO2-C3H8-CH4, to verify multiple analyzers at the same time.  If you use standard binary span gases, you must run separate response tests for each analyzer.  In designing your experimental setup, avoid pressure pulsations due to stopping the flow through the gas-blending device.  The change in gas concentration must be at least 20 % of the analyzer's range.
(3) Data collection. (i) Start the flow of zero gas.
(ii) Allow for stabilization, accounting for transport delays and the slowest analyzer's full response.
(iii) Start recording data.  For this verification you must record data at a frequency greater than or equal to that of the updating-recording frequency used during emission testing.  You may not use interpolation or filtering to alter the recorded values.
(iv) Switch the flow to allow the blended span gases to flow to the analyzer.  If you intend to use the data from this test to determine t50 for time alignment, record this time as t0.
(v) Allow for transport delays and the slowest analyzer's full response.
(vi) Switch the flow to allow zero gas to flow to the analyzer.  If you intend to use the data from this test to determine t50 for time alignment, record this time as t100.
(vii) Allow for transport delays and the slowest analyzer's full response.
(viii) Repeat the steps in paragraphs (d)(3)(iv) through (vii) of this section to record seven full cycles, ending with zero gas flowing to the analyzers.
(ix) Stop recording.
*	*	*	*	*
(g) Optional procedure.  Instead of using a three-way valve to switch between zero and span gases, you may use a fast-acting two-way valve to switch sampling between ambient air and span gas at the probe inlet.  For this alternate procedure, the following provisions apply:
(1) If your probe is sampling from a continuously flowing gas stream (such as a CVS tunnel), you may adjust the span gas flow rate to be different than the sample flow rate.
(2) If your probe is sampling from a gas stream that is not continuously flowing (such as a raw exhaust stack), you must adjust the span gas flow rate to be less than the sample flow rate so ambient air is always drawn into the probe inlet.  This avoids errors associated with overflowing span gas out of the probe inlet and drawing the span gas back in when sampling ambient air.
(3) When sampling ambient air with or without span gas, all the analyzer readings must be stable within +-0.5 % of the target gas concentration step size.  If any analyzer reading is outside the specified range, you must resolve the problem and verify that all the analyzer readings meet this specification.
(4) For oxygen analyzers, you may use purified N2 as the zero gas and ambient air (plus purified N2 if needed) as the reference gas.  Perform the verification with seven repeat measurements that each consist of stabilizing with purified N2, switching to ambient air and observing the analyzer's response rise and stabilized reading, followed by switching back to purified N2 and observing the analyzer's response fall and stabilized reading.

95. Section 1065.309 is amended by revising paragraphs (a) and (d)(2) and adding paragraphs (g) and (h) to read as follows:
§1065.309 Continuous gas analyzer system-response and updating-recording verification -- for gas analyzers continuously compensated for other gas species.
(a) Scope and frequency.  This section describes a verification procedure for system response and updating-recording frequency for continuous gas analyzers that output a single gas species mole fraction (i.e., concentration) based on a continuous combination of multiple gas species measured with multiple detectors (i.e., gas analyzers continuously compensated for other gas species).  See §1065.308 for verification procedures that apply to continuous gas analyzers that are not continuously compensated for other gas species or that use only one detector for gaseous species.  Perform this verification to determine the system response of the continuous gas analyzer and its sampling system.  This verification is required for continuous gas analyzers used for transient or ramped-modal testing.  You need not perform this verification for batch gas analyzers or for continuous gas analyzers that are used only for discrete-mode testing.  For this check we consider water vapor a gaseous constituent.  This verification does not apply to any processing of individual analyzer signals that are time-aligned to their t50 times and were verified according to §1065.308.  For example, this verification does not apply to correction for water removed from the sample done in post-processing according to §1065.659 (40 CFR 1066.640 for vehicle testing) and it does not apply to NMHC determination from THC and CH4 according to §1065.660.  Perform this verification after initial installation (i.e., test cell commissioning) and after any modifications to the system that would change the system response.
*	*	*	*	*
(d)	*	*	*
(2) Equipment setup.  We recommend using minimal lengths of gas transfer lines between all connections and fast-acting three-way valves (2 inlets, 1 outlet) to control the flow of zero and blended span gases to the sample system's probe inlet or a tee near the outlet of the probe.  If you inject the gas at a tee near the outlet of the probe, you may correct the transformation time, t50, for an estimate of the transport time from the probe inlet to the tee.  Normally the gas flow rate is higher than the sample flow rate and the excess is overflowed out the inlet of the probe.  If the gas flow rate is lower than the sample flow rate, the gas concentrations must be adjusted to account for the dilution from ambient air drawn into the probe.  We recommend you use the final, stabilized analyzer reading as the final gas concentration.   Select span gases for the species being continuously combined, other than H2O.  Select concentrations of compensating species that will yield concentrations of these species at the analyzer inlet that covers the range of concentrations expected during testing.  You may use binary or multi-gas span gases.  You may use a gas blending or mixing device to blend span gases.  A gas blending or mixing device is recommended when blending span gases diluted in N2 with span gases diluted in air.  You may use a multi-gas span gas, such as NO-CO-CO2-C3H8-CH4, to verify multiple analyzers at the same time. In designing your experimental setup, avoid pressure pulsations due to stopping the flow through the gas blending device.  The change in gas concentration must be at least 20 % of the analyzer's range.  If H2O correction is applicable, then span gases must be humidified before entering the analyzer; however, you may not humidify NO2 span gas by passing it through a sealed humidification vessel that contains water.  You must humidify NO2 span gas with another moist gas stream.  We recommend humidifying your NO-CO-CO2-C3H8-CH4, balance N2 blended gas by flowing the gas mixture through a sealed vessel that humidifies the gas by bubbling it through distilled water and then mixing the gas with dry NO2 gas, balance purified air.  If your system does not use a sample dryer to remove water from the sample gas, you must humidify your span gas to the highest sample H2O content that you estimate during emission sampling.  If your system uses a sample dryer during testing, it must pass the sample dryer verification check in §1065.342, and you must humidify your span gas to an H2O content greater than or equal to the level determined in §1065.145(e)(2).  If you are humidifying span gases without NO2, use good engineering judgment to ensure that the wall temperatures in the transfer lines, fittings, and valves from the humidifying system to the probe are above the dewpoint required for the target H2O content.  If you are humidifying span gases with NO2, use good engineering judgment to ensure that there is no condensation in the transfer lines, fittings, or valves from the point where humidified gas is mixed with NO2 span gas to the probe.  We recommend that you design your setup so that the wall temperatures in the transfer lines, fittings, and valves from the humidifying system to the probe are at least 5 ºC above the local sample gas dewpoint.  Operate the measurement and sample handling system as you do for emission testing.  Make no modifications to the sample handling system to reduce the risk of condensation.  Flow humidified gas through the sampling system before this check to allow stabilization of the measurement system's sampling handling system to occur, as it would for an emission test.
*	*	*	*	*
(g) Optional procedure.  Follow the optional procedures in §1065.308(g), noting that you may use compensating gases mixed with ambient air for oxygen analyzers.
(h) Analyzers with H2O compensation sampling downstream of a sample dryer.  You may omit humidifying the span gas as described in this paragraph (h).  If an analyzer compensates only for H2O, you may apply the requirements of §1065.308 instead of the requirements of this section. You may omit humidifying the span gas if you meet the following conditions:
(1) The analyzer is located downstream of a sample dryer.
(2) The maximum value for H2O mole fraction downstream of the dryer must be less than or equal to 0.010.  Verify this during each sample dryer verification according to §1065.342.

            MEASUREMENT OF ENGINE PARAMETERS AND AMBIENT CONDITIONS

96. Section 1065.310 is amended by revising paragraph (d) to read as follows:
§1065.310 Torque calibration.
*	*	*	*	*
(d) Strain gage, load transducer, 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 as part of the reference torque determination) 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 force output from the reference meter (such as a strain gage, load transducer, or proving ring) 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 the reference meter's measurement axis and perpendicular to the dynamometer's rotational axis.

97. Section 1065.315 is amended by revising paragraph (a)(2) to read as follows:
§1065.315 Pressure, temperature, and dewpoint calibration.
(a) 	*	*	*
(2) Temperature.  We recommend digital dry-block or stirred-liquid temperature calibrators, with data logging capabilities to minimize transcription errors.  We recommend using calibration reference quantities that are NIST-traceable within 0.5 % uncertainty.  You may perform linearity verification for temperature measurement systems with thermocouples, RTDs, and thermistors by removing the sensor from the system and using a simulator in its place.  Use a NIST-traceable simulator that is independently calibrated and, as appropriate, cold-junction compensated.  The simulator uncertainty scaled to absolute temperature must be less than 0.5 % of Tmax.  If you use this option, you must use sensors that the supplier states are accurate to better than 0.5 % of Tmax compared with their standard calibration curve.
*	*	*	*	*

98. Section 1065.341 is amended by revising the section heading and paragraphs (a) introductory text, (d) introductory text, and (f)(3) to read as follows:
§1065.341 CVS, PFD, 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.  You may use the same procedure to verify PFDs and batch samplers.  For purposes of PFD and batch sampler verification, read the term CVS to mean PFD or batch sampler as appropriate.  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 CO2 or CO.  A failed propane check might indicate one or more problems that may require corrective action, as follows:
*	*	*	*	*
(d) If you performed the vacuum-side leak verification of the HC sampling system as described in paragraph (c)(8) of this section, you may use the HC contamination procedure in §1065.520(f) to verify HC contamination. Otherwise, zero, span, and verify contamination of the HC sampling system, as follows:
*	*	*	*	*
(f) 	*	*	*
(3) Calculate total C3H8 mass based on your CVS and HC data as described in §1065.650 (40 CFR 1066.610 for vehicle testing) and §1065.660, using the molar mass of C3H8, MC3H8, instead the effective molar mass of HC, MHC.
*	*	*	*	*

99. Section 1065.350 is amended by revising paragraphs (d) and (e) to read as follows:
§1065.350 H2O interference verification for CO2 NDIR analyzers.
*	*	*	*	*
(d) Procedure.  Perform the interference verification as follows:
(1) Start, operate, zero, and span the CO2 NDIR analyzer as you would before an emission test.  If the sample is passed through a dryer during emission testing, you may run this verification test with the dryer if it meets the requirements of §1065.342.  Operate the dryer at the same conditions as you will for an emission test.  You may also run this verification test without the sample dryer.
(2) Create a humidified test gas by bubbling zero gas that meets the specifications in §1065.750 through distilled H2O in a sealed vessel.  If the sample is not passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the maximum expected during emission testing.  If the sample is passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the level determined in §1065.145(e)(2) for that dryer.
(3) Introduce the humidified test gas into the sample system.  You may introduce it downstream of any sample dryer, if one is used during testing.
(4) If the sample is not passed through a dryer during this verification test, measure the H2O mole fraction, xH2O, of the humidified test gas, as close as possible to the inlet of the analyzer.  For example, measure dewpoint, Tdew, and absolute pressure, ptotal, to calculate xH2O.  Verify that the H2O content meets the requirement in paragraph (d)(2) of this section.  If the sample is passed through a dryer during this verification test, you must verify that the H2O content of the humidified test gas downstream of the vessel meets the requirement in paragraph (d)(2) of this section based on either direct measurement of the H2O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature.  Use good engineering judgment to estimate the H2O content.  For example, you may use previous direct measurements of H2O content to verify the vessel's level of saturation.
(5) If a sample dryer is not used in this verification test, use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves from the point where xH2O is measured to the analyzer.  We recommend that you design your system so the wall temperatures in the transfer lines, fittings, and valves from the point where xH2O is measured to the analyzer are at least 5 ºC above the local sample gas dewpoint.
(6) Allow time for the analyzer response to stabilize.  Stabilization time may include time to purge the transfer line and to account for analyzer response.
(7) 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 (0.0 +-0.4) mmol/mol.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your CO2 sampling system and your emission-calculation procedures, the H2O interference for your CO2 NDIR analyzer always affects your brake-specific emission results within 0.5 % of each of the applicable standards.  This specification also applies for vehicle testing, except that it relates to emission results in g/mile or g/kilometer.
(2) You may use a CO2 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.

100. Section 1065.355 is amended by revising paragraph (d) to read as follows:
§1065.355 H2O and CO2 interference verification for CO NDIR analyzers.
*	*	*	*	*
(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.  If the sample is passed through a dryer during emission testing, you may run this verification test with the dryer if it meets the requirements of §1065.342.  Operate the dryer at the same conditions as you will for an emission test.  You may also run this verification test without the sample dryer.
(2) Create a humidified CO2 test gas by bubbling a CO2 span gas that meets the specifications in §1065.750 through distilled H2O in a sealed vessel.  If the sample is not passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the maximum expected during emission testing.  If the sample is passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the level determined in §1065.145(e)(2) for that dryer.  Use a CO2 span gas concentration at least as high as the maximum expected during testing.
(3) Introduce the humidified CO2 test gas into the sample system.  You may introduce it downstream of any sample dryer, if one is used during testing.
(4) If the sample is not passed through a dryer during this verification test, measure the H2O mole fraction, xH2O, of the humidified CO2 test gas as close as possible to the inlet of the analyzer.  For example, measure dewpoint, Tdew, and absolute pressure, ptotal, to calculate xH2O.  Verify that the H2O content meets the requirement in paragraph (d)(2) of this section.  If the sample is passed through a dryer during this verification test, you must verify that the H2O content of the humidified test gas downstream of the vessel meets the requirement in paragraph (d)(2) of this section based on either direct measurement of the H2O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature.  Use good engineering judgment to estimate the H2O content.  For example, you may use previous direct measurements of H2O content to verify the vessel's level of saturation.
(5) If a sample dryer is not used in this verification test, use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves from the point where xH2O is measured to the analyzer.  We recommend that you design your system so that the wall temperatures in the transfer lines, fittings, and valves from the point where xH2O is measured to the analyzer are at least 5 ºC above the local sample gas dewpoint.
(6) Allow time for the analyzer response to stabilize.  Stabilization time may include time to purge the transfer line and to account for analyzer response.
(7) While the analyzer measures the sample's concentration, record its output for 30 seconds.  Calculate the arithmetic mean of this data.
(8) The analyzer meets the interference verification if the result of paragraph (d)(7) of this section meets the tolerance in paragraph (c) of this section.
(9) You may also run interference procedures for CO2 and H2O separately.  If the CO2 and H2O levels used are higher than the maximum levels expected during testing, you may scale down each observed interference value by multiplying the observed interference by the ratio of the maximum expected concentration value to the actual value used during this procedure.  You may run separate interference concentrations of H2O (down to 0.025 mol/mol H2O content) that are lower than the maximum levels expected during testing, but you must scale up the observed H2O interference by multiplying the observed interference by the ratio of the maximum expected H2O concentration value to the actual value used during this procedure.  The sum of the two scaled interference values must meet the tolerance in paragraph (c) of this section.
*	*	*	*	*

                           HYDROCARBON MEASUREMENTS

101. Section 1065.360 is amended by revising paragraphs (a)(3), (b), (d), (e) introductory text, and (e)(4) to read as follows:
§1065.360 FID optimization and verification.
(a)	*	*	*
(3) Verify the CH4 response within 185 days before testing as described in paragraph (e) of this section.
(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.  For a FID that measures THC, calibrate using C3H8 calibration gases that meet the specifications of §1065.750.  For a FID that measures CH4, calibrate using CH4 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 O2 expected during testing.  If you use a FID to measure CH4 downstream of a nonmethane cutter, you may calibrate that FID using CH4 calibration gases with the cutter.  Regardless of the calibration gas composition, calibrate on a carbon number basis of one (C1).  For example, if you use a C3H8 span gas of concentration 200 mol/mol, span the FID to respond with a value of 600 mol/mol.  As another example, if you use a CH4 span gas with a concentration of 200 mol/mol, span the FID to respond with a value of 200 mol/mol.
*	*	*	*	*
(d) THC FID CH4 response factor determination.  This procedure is only for FID analyzers that measure THC.  Since FID analyzers generally have a different response to CH4 versus C3H8, determine each THC-FID analyzer's CH4 response factor, RFCH4[THC-FID], after FID optimization.  Use the most recent RFCH4[THC-FID] measured according to this section in the calculations for HC determination described in §1065.660 to compensate for CH4 response.  Determine RFCH4[THC-FID] as follows, noting that you do not determine RFCH4[THC-FID] for FIDs that are calibrated and spanned using CH4 with a nonmethane cutter:
(1) Select a C3H8 span gas concentration that you use to span your analyzers before emission testing.  Use only span gases that meet the specifications of §1065.750.  Record the C3H8 concentration of the gas.
(2) Select a CH4 span gas concentration that you use to span your analyzers before emission testing.  Use only span gases that meet the specifications of §1065.750.  Record the CH4 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 C3H8.  Calibrate on a carbon number basis of one (C1).  For example, if you use a C3H8 span gas of concentration 200 mol/mol, span the FID to respond with a value of 600 mol/mol.
(5) Zero the FID with a zero gas that you use for emission testing.
(6) Span the FID with the C3H8 span gas that you selected under paragraph (d)(1) of this section.
(7) Introduce at the sample port of the FID analyzer, the CH4 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 CH4 concentration, record 30 seconds of sampled data.  Calculate the arithmetic mean of these values.
(10) For analyzers with multiple ranges, you need to perform the procedure in this paragraph (d) only on a single range.
(11) Divide the mean measured concentration by the recorded span concentration of the CH4 calibration gas.  The result is the FID analyzer's response factor for CH4, RFCH4[THC-FID].
(e) THC FID CH4 response verification.  This procedure is only for FID analyzers that measure THC.  If the value of RFCH4[THC-FID] from paragraph (d) of this section is within 5 % of its most recent previously determined value, the THC FID passes the CH4 response verification.  For example, if the most recent previous value for RFCH4[THC-FID] 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 %.  Verify RFCH4[THC-FID] as follows:
*	*	*	*	*
(4) For analyzers with multiple ranges, you need to perform the procedure in this paragraph (e) only on a single range.
*	*	*	*	*

102. Section 1065.362 is amended by adding paragraph (d)(15) to read as follows:
§1065.362 Non-stoichiometric raw exhaust FID O2 interference verification.
*	*	*	*	*
(d)	*	*	*
(15) For analyzers with multiple ranges, you need to perform the procedure in this paragraph (d) only on a single range.

103. Section 1065.365 is amended by revising paragraphs (a), (b), (d)(1), (e)(1), (f) introductory text, and (f)(1) to read as follows:
§1065.365 Nonmethane cutter penetration fractions.
(a) Scope and frequency.  If you use a FID analyzer and a nonmethane cutter (NMC) to measure methane (CH4), determine the nonmethane cutter's penetration fractions of CH4, PFCH4, and ethane, PFC2H6.  As detailed in this section, these penetration fractions may be determined as a combination of NMC penetration fractions and FID analyzer response factors, depending on your particular NMC and FID analyzer configuration.  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 an exhaust sample stream before the FID analyzer measures the remaining hydrocarbon concentration.  An ideal nonmethane cutter would have a CH4 penetration fraction, PFCH4, of 1.000, and the penetration fraction for all other nonmethane hydrocarbons would be 0.000, as represented by PFC2H6.  The emission calculations in §1065.660 use the measured values from this verification to account for less than ideal NMC performance.
*	*	*	*	*
(d)	*	*	*
(1) Select CH4 and C2H6 analytical gas mixtures and ensure that both mixtures meet the specifications of §1065.750.  Select a CH4 concentration that you would use for spanning the FID during emission testing and select a C2H6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value.  For CH4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
*	*	*	*	*
(e)	*	*	*
(1) Select CH4 and C2H6 analytical gas mixtures and ensure that both mixtures meet the specifications of §1065.750.  Select a CH4 concentration that you would use for spanning the FID during emission testing and select a C2H6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard and the C2H6 concentration typical of the peak total hydrocarbon (THC) concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value.  For CH4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
*	*	*	*	*
(f) Procedure for a FID calibrated with CH4, bypassing the NMC.  If you use a FID with an NMC that is calibrated with CH4, by bypassing the NMC, determine its combined ethane (C2H6) response factor and penetration fraction, RFPFC2H6[NMC-FID] , as well as its CH4 penetration fraction, PFCH4[NMC-FID], as follows:
(1) Select CH4 and C2H6 analytical gas mixtures and ensure that both mixtures meet the specifications of §1065.750.  Select a CH4 concentration that you would use for spanning the FID during emission testing and select a C2H6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value.  For CH4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
*	*	*	*	*

104.   A new §1065.369 is added to subpart D to read as follows:
§1065.369 H2O, CO, and CO2 interference verification for photoacoustic alcohol analyzers.
(a) Scope and frequency.  If you measure ethanol or methanol using a photoacoustic analyzer, verify the amount of H2O, CO, and CO2 interference after initial analyzer installation and after major maintenance.
(b) Measurement principles.  H2O, CO, and CO2 can positively interfere with a photoacoustic analyzer by causing a response similar to ethanol or methanol.  If the photoacoustic 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.  Photoacoustic analyzers must have combined interference that is within (0.0 +- 0.5) umol/mol.  We strongly recommend a lower interference that is within (0.0 +- 0.25) umol/mol.
(d) Procedure.  Perform the interference verification by following the procedure in §1065.375(d), comparing the results to paragraph (c) of this section.

                           NOx AND N2O MEASUREMENTS

105. Section 1065.370 is amended by revising paragraphs (d)(9) and (e)(5) to read as follows:
§1065.370 CLD CO2 and H2O quench verification.
*	*	*	*	*
(d) *	*	*	*	*
(9) While flowing NO and CO2 through the gas divider, stabilize the output of the gas divider.  Determine the CO2 concentration from the gas divider output, applying gas property correction as necessary to ensure accurate gas division, or measure it using an NDIR.  Record this concentration, xCO2act, and use it in the quench verification calculations in §1065.675.  Alternatively, you may use a simple gas blending device and use an NDIR to determine this CO2 concentration.  If you use an NDIR, it must meet the requirements of this part for laboratory testing and you must span it with the CO2 span gas from paragraph (d)(4) of this section.
*	*	*	*	*
(e) *	*	*	*	*
(5) Humidify the NO span gas by bubbling it through distilled H2O in a sealed vessel.  If the humidified NO span gas sample does not pass through a sample dryer for this verification test, control the vessel temperature to generate an H2O level approximately equal to the maximum mole fraction of H2O expected during emission testing.  If the humidified NO span gas sample does not pass through a sample dryer, the quench verification calculations in §1065.675 scale the measured H2O quench to the highest mole fraction of H2O expected during emission testing.  If the humidified NO span gas sample passes through a dryer for this verification test, control the vessel temperature to generate an H2O level at least as high as the level determined in §1065.145(e)(2).  For this case, the quench verification calculations in §1065.675 do not scale the measured H2O quench.
*	*	*	*	*

106. Section 1065.375 is amended by revising paragraph (d) to read as follows:
§1065.375 Interference verification for N2O analyzers.
*	*	*	*	*
(d) Procedure.  Perform the interference verification as follows:
(1) Start, operate, zero, and span the N2O analyzer as you would before an emission test.  If the sample is passed through a dryer during emission testing, you may run this verification test with the dryer if it meets the requirements of §1065.342.  Operate the dryer at the same conditions as you will for an emission test.  You may also run this verification test without the sample dryer.
(2) Create a humidified test gas by bubbling a multi component span gas that incorporates the target interference species and meets the specifications in §1065.750 through distilled H2O in a sealed vessel.  If the sample is not passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the maximum expected during emission testing.  If the sample is passed through a dryer during emission testing, control the vessel temperature to generate an H2O level at least as high as the level determined in §1065.145(e)(2) for that dryer.  Use interference span gas concentrations that are at least as high as the maximum expected during testing.
(3) Introduce the humidified interference test gas into the sample system.  You may introduce it downstream of any sample dryer, if one is used during testing.
(4) If the sample is not passed through a dryer during this verification test, measure the H2O mole fraction, xH2O, of the humidified interference test gas as close as possible to the inlet of the analyzer.  For example, measure dewpoint, Tdew, and absolute pressure, ptotal, to calculate xH2O.  Verify that the H2O content meets the requirement in paragraph (d)(2) of this section.  If the sample is passed through a dryer during this verification test, you must verify that the H2O content of the humidified test gas downstream of the vessel meets the requirement in paragraph (d)(2) of this section based on either direct measurement of the H2O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature.  Use good engineering judgment to estimate the H2O content.  For example, you may use previous direct measurements of H2O content to verify the vessel's level of saturation.
(5) If a sample dryer is not used in this verification test, use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves from the point where xH2O is measured to the analyzer.  We recommend that you design your system so that the wall temperatures in the transfer lines, fittings, and valves from the point where xH2O is measured to the analyzer are at least 5 ºC above the local sample gas dewpoint.
(6) Allow time for the analyzer response to stabilize.  Stabilization time may include time to purge the transfer line and to account for analyzer response.
(7) While the analyzer measures the sample's concentration, record its output for 30 seconds.  Calculate the arithmetic mean of this data.  When performed with all the gases simultaneously, this is the combined interference.
(8) The analyzer meets the interference verification if the result of paragraph (d)(7) of this section meets the tolerance in paragraph (c) of this section.
(9) You may also run interference procedures separately for individual interference gases.  If the interference gas levels used are higher than the maximum levels expected during testing, you may scale down each observed interference value (the arithmetic mean of 30 second data described in paragraph (d)(7) of this section) by multiplying the observed interference by the ratio of the maximum expected concentration value to the actual value used during this procedure.  You may run separate interference concentrations of H2O (down to 0.025 mol/mol H2O content) that are lower than the maximum levels expected during testing, but you must scale up the observed H2O interference by multiplying the observed interference by the ratio of the maximum expected H2O concentration value to the actual value used during this procedure.  The sum of the scaled interference values must meet the tolerance for combined interference as specified in paragraph (c) of this section.

107. Section 1065.376 is amended by revising paragraphs (b) and (d)(2) to read as follows:
§1065.376 Chiller NO2 penetration.
*	*	*	*	*
(b) Measurement principles.  A chiller removes H2O, which can otherwise interfere with a NOx measurement.  However, liquid H2O remaining in an improperly designed chiller can remove NO2 from the sample.  If a chiller is used without an NO2-to-NO converter upstream, it could remove NO2 from the sample prior NOx measurement.
*	*	*	*	*
(d)	*	*	*
(2) Equipment setup and data collection.  (i) Zero and span the total NOx gas analyzer(s) as you would before emission testing.
(ii) Select an NO2 calibration gas, balance gas of dry air, that has an NO2 concentration within +-5 % of the maximum NO2 concentration expected during testing.
(iii) Overflow this calibration gas at the gas sampling system's probe or overflow fitting.  Allow for stabilization of the total NOx response, accounting only for transport delays and instrument response.
(iv) Calculate the mean of 30 seconds of recorded total NOx data and record this value as xNOxref.
(v) Stop flowing the NO2 calibration gas.
(vi) Next saturate the sampling system by overflowing a dewpoint generator's output, set at a dewpoint of 50 C, to the gas sampling system's probe or overflow fitting.  Sample the dewpoint generator's output through the sampling system and chiller for at least 10 minutes until the chiller is expected to be removing a constant rate of H2O.
(vii) Immediately switch back to overflowing the NO2 calibration gas used to establish xNOxref.   Allow for stabilization of the total NOx response, accounting only for transport delays and instrument response.  Calculate the mean of 30 seconds of recorded total NOx data and record this value as xNOxmeas.
(viii) Correct xNOxmeas to xNOxdry based upon the residual H2O vapor that passed through the chiller at the chiller's outlet temperature and pressure.
*	*	*	*	*

Subpart E -- [Amended]
108. Section 1065.405 is amended by revising paragraph (a) and adding paragraph (f) to read as follows:
§1065.405 Test engine preparation and maintenance.
This part 1065 describes how to test engines for a variety of purposes, including certification testing, production-line testing, and in-use testing.  Depending on which type of testing is being conducted, different preparation and maintenance requirements apply for the test engine.
(a) If you are testing an emission-data engine for certification, make sure it is built to represent production engines, consistent with paragraph (f) of this section.  This includes governors that you normally install on production engines.  Production engines should also be tested with their installed governors.  If you do not install governors on production engines, simulate a governor that is representative of a governor that others will install on your production engines.  In certain circumstances, you may incorporate test cell components to simulate an in-use configuration, consistent with good engineering judgment.  For example, §§1065.122 and 1065.125 allow the use of test cell components to represent engine cooling and intake air systems.
*	*	*	*	*
(f) This paragraph (f) defines the components that are considered to be part of the engine for laboratory testing.  See §1065.110 for provisions related to system boundaries with respect to work inputs and outputs.
(1) This paragraph (f)(1) describes certain criteria for considering a component to be part of the test engine.  The criteria are intended to apply broadly, such that a component would generally be considered part of the engine in cases of uncertainty.  An engine-related component meeting all the following criteria is considered to be part of the test engine for purposes of testing and for stabilizing emission levels, preconditioning, and measuring emission levels:
(i) The component directly affects the functioning of the engine, is related to the control of emissions, or transmits engine power.  This would include engine cooling systems, engine controls, and transmissions.
(ii) The component is covered by the applicable certificate of conformity.  For example, this criterion would typically exclude radiators not described in an application for certification.
(iii) The component is not part of the laboratory setup, or it is used for other engines.
(2) Although components meeting the criteria specified in paragraphs (f)(1)(i) or (ii) of this section, but not the criterion specified in paragraph (f)(1)(iii) of this section, are not considered to be part of the test engine, you must precondition these components along with the test engine.

Subpart F -- [Amended]
109.   Section 1065.501 is amended as follows:
   a. By redesignating paragraphs (b) through (d) as paragraphs (c) through (e), respectively.
   b. By adding a new paragraph (b).
   c. By revising the redesignated paragraph (c)(2) introductory text.
§1065.501 Overview.
*	*	*	*	*
(b) Unless we specify otherwise, you may control the regeneration timing of infrequently regenerated aftertreatment devices such as diesel particulate filters using good engineering judgment.  You may control the regeneration timing using a sequence of engine operating conditions or you may initiate regeneration with an external regeneration switch or other command.  This provision would also allow you to ensure that a regeneration event does not occur during an emission test.
(c) 	*	*	*
(2) Steady-state cycles.  Steady-state duty cycles are typically specified in the standard-setting part as a list of discrete operating points (modes or notches), where each operating point has one value of a normalized speed command and one value of a normalized torque (or power) command.  Ramped-modal cycles for steady-state testing also list test times for each mode and transition times between modes where speed and torque are linearly ramped between modes, even for cycles with % power.  Start a steady-state cycle as a hot running test, where you start to measure emissions after an engine is started, warmed up and running.  Run a steady-state duty cycle as a discrete-mode cycle or a ramped-modal cycle, as follows:
*	*	*	*	*

110.   A new §1065.516 is added to subpart E to read as follows:
§1065.516 Sample system decontamination and preconditioning.
This section describes how to manage the impact of sampling system contamination on emission measurements.  Use good engineering judgement to determine if you should decontaminate and precondition your sampling system.  Contamination occurs when a regulated pollutant accumulates in the sample system in a high enough concentration to cause release during emission tests.  Hydrocarbons and PM are generally the only regulated pollutants that contaminate sample systems.  A sampling system is considered decontaminated if the contaminants are in equilibrium with measured exhaust emissions.  Note that although this section focuses on avoiding excessive contamination of sample systems, you must also use good engineering judgment to avoid loss of sample to a sample system that is too clean.  The goal of decontamination is not to perfectly clean the sample system, but rather to achieve equilibrium between the sample system and the exhaust so emission components are neither lost to nor entrained from the sample system.
(a) You may perform contamination checks as follows to determine if decontamination is needed:
(1) For dilute exhaust sampling systems, measure hydrocarbon and PM emissions by sampling with the CVS dilution air turned on, without an engine connected to it.
(2) For raw analyzers and systems that collect PM samples from raw exhaust, measure hydrocarbon and PM emissions by sampling purified air or nitrogen.
(3) When calculating zero emission levels, apply all applicable corrections, including initial THC contamination and diluted (CVS) exhaust background corrections.
(4) Sampling systems are considered contaminated if either of the following conditions applies:
(i) The hydrocarbon emission level exceeds 2 % of the flow-weighted mean wet, net concentration expected at the HC standard.
(ii) The PM emission level exceeds 5 % of the level expected at the standard and exceeds 20 μg on a 47 mm PTFE membrane filter.
(b) To precondition/decontaminate sampling systems, use the following recommended procedure or use good engineering judgment to select a different procedure:
(1) Start the engine and use good engineering judgment to operate it at a condition that generates high exhaust temperatures at the sample probe inlet.
(2) Operate any dilution systems at their expected flow rates.  Prevent aqueous condensation in the dilution systems.
(3) Operate any PM sampling systems at their expected flow rates.
(4) Sample PM for at least 10 min using any sample media. You may change sample media at any time during this process and you may discard them without weighing them.
(5) You may purge any gaseous sampling systems that do not require decontamination during this procedure.
(6) You may conduct calibrations or verifications on any idle equipment or analyzers during this procedure.
(c) If your sampling system is still contaminated following the procedures specified in paragraph (b) of this section, you may use more aggressive procedures to decontaminate the sampling system, as long as the decontamination does not cause the sampling system to be cleaner than an equilibrium condition such that artificially low emission measurements may result.

111.   A new §1065.518 is added to subpart E to read as follows:
§1065.518 Engine preconditioning.
(a) This section applies for engines where measured emissions are affected by prior operation, such as with a diesel engine that relies on urea-based selective catalytic reduction.  Note that §1065.520(e) allows you to run practice duty cycles before the emission test; this section recommends how to do this for the purpose of preconditioning the engine.  We may test your engine after completing only the minimum amount of preconditioning recommended in this section.  For subsequent testing, such as steady-state testing following transient testing, we may consider the previous test cycle as preconditioning.  Follow the standard-setting part if it specifies a different engine preconditioning procedure.
(b) The intent of engine preconditioning is to manage the representativeness of emissions over the duty cycle, as described in §1065.10(c)(1), by conditioning the engine to a state where its emissions are representative of in-use operation.
(c) This paragraph (c) specifies the engine preconditioning procedures for different types of duty cycles.  You may measure emissions during preconditioning cycles, as long as you perform a predefined number of preconditioning cycles.  You must identify before each duty cycle whether it is a preconditioning cycle or an emission test.  You may not abort an emission test based on emissions measured during preconditioning.
(1) Cold-start transient cycle.  Precondition the engine by running at least one cold-start or hot-start transient cycle.  Immediately after completing the last preconditioning cycle, shut down the engine and begin the cold soak as described in §1065.530(a)(1).
(2) Hot-start transient cycle.  Precondition the engine by running at least one hot-start transient cycle.  Shut down the engine after completing the last preconditioning cycle and start the hot-start transient test as soon as practical.
(3) Hot-running transient cycle.  Precondition the engine by running at least one hot-running transient cycle.  Start the official hot-running transient cycle as soon as practical after completing the last preconditioning cycle.
(4) Discrete-mode cycle for steady-state testing.  Precondition the engine at the same operating condition as the next  test mode, unless the standard-setting part specifies sampling time limits.
(5) Ramped-modal cycle for steady-state testing.  If you run the ramped-modal cycle after a transient test, additional preconditioning is allowed, but not required.  If you perform additional preconditioning, we recommend running the first non-idle mode of the ramped-modal cycle or a mode approximating 50 % power.
(d) You may conduct calibrations or verifications on any idle equipment or analyzers during engine preconditioning.

112.   Section 1065.520 is amended by removing paragraph (g) and revising paragraphs (a), (e), and (f) to read as follows:
§1065.520 Pre-test verification procedures and pre-test data collection.
(a) For tests in which you measure PM emissions, follow the procedures for PM sample preconditioning and tare weighing according to §1065.590.
*	*	*	*	*
(e) You may perform a final calibration of the speed, torque, and proportional-flow control systems, which may include performing practice duty cycles (or portions of duty cycles).  This may be done in conjunction with the preconditioning in §1065.518.
(f) Verify the amount of nonmethane hydrocarbon contamination in the exhaust and background HC sampling systems within 8 hours before the start of the first test interval of each duty-cycle sequence for laboratory tests.  You may verify the contamination of a background HC sampling system by reading the last bag fill and purge using zero gas.  For any NMHC measurement system that involves separately measuring CH4 and subtracting it from a THC measurement or for any CH4 measurement system that uses an NMC, verify the amount of THC contamination using only the THC analyzer response.  There is no need to operate any separate CH4 analyzer for this verification; however, you may measure and correct for THC contamination in the CH4 sample train for the cases where NMHC is determined by subtracting CH4 from THC or, where CH4 is determined, using an NMC as configured in §1065.365(d), (e), and (f); and using the calculations in §1065.660(b)(2). Perform this verification as follows:
(1) Select the HC analyzer range for measuring the flow-weighted mean concentration expected at the HC standard.
(2) Zero the HC analyzer at the analyzer zero or sample port. Note that FID zero and span balance gases may be any combination of purified air or purified nitrogen that meets the specifications of §1065.750.  We recommend FID analyzer zero and span gases that contain approximately the flow-weighted mean concentration of O2 expected during testing.
(3) Span the HC analyzer using span gas introduced at the analyzer span or sample port.  Span on a carbon number basis of one (C1).  For example, if you use a C3H8 span gas of concentration 200 mol/mol, span the FID to respond with a value of 600 mol/mol.
(4) Overflow zero gas at the HC probe inlet or into a tee near the probe outlet.
(5) Measure the THC concentration in the sampling and background systems as follows:
(i) For continuous sampling, record the mean THC concentration as overflow zero gas flows.
(ii) For batch sampling, fill the sample medium (e.g., bag) and record its mean THC concentration.
(iii) For the background system, record the mean THC concentration of the last fill and purge.
(6) Record this value as the initial THC concentration, xTHC[THC-FID]init, and use it to correct measured values as described in §1065.660.
(7) You may correct the measured initial THC concentration for drift as follows:
(i) For batch and continuous HC analyzers, after determining the initial THC concentration, flow zero gas to the analyzer zero or sample port.  When the analyzer reading is stable, record the mean analyzer value.
(ii) Flow span gas to the analyzer span or sample port.  When the analyzer reading is stable, record the mean analyzer value.
(iii) Use mean analyzer values from paragraphs (f)(2), (3), (7)(i), and (7)(ii) of this section to correct the initial THC concentration recorded in paragraph (f)(6) of this section for drift, as described in §1065.550.
(8) If any of the xTHC[THC-FID]init values exceed the greatest of the following values, determine the source of the contamination and take corrective action, such as purging the system during an additional preconditioning cycle or replacing contaminated portions:
(i) 2 % of the flow-weighted mean wet, net concentration expected at the HC (THC or NMHC) standard.
(ii) 2 % of the flow-weighted mean wet, net concentration of HC (THC or NMHC) measured during testing.
(iii) 2 mol/mol.
(9) If corrective action does not resolve the deficiency, you may request to use the contaminated system as an alternate procedure under §1065.10.

113. Section 1065.526 is amended by revising paragraphs (c)(3) and (d)(1) to read as follows:
§1065.526 Repeating of void modes or test intervals.
*	*	*	*	*
(c)	*	*	*
(3) Precondition the engine by operating it at the mode at which the test was interrupted and continue with the duty cycle as specified in the standard-setting part.
(d)	*	*	*	*	*
(1) Use good engineering judgment to restart (as applicable) and precondition the engine to the same condition as would apply for normal testing.  This may require you to complete the voided test interval.  For example, you may generally repeat a hot-start test of a heavy-duty highway engine after completing the voided hot-start test and allowing the engine to soak for 20 minutes.
*	*	*	*	*

114.   Section 1065.530 is amended by removing paragraph (b)(13) and revising paragraphs (a), (b)(12), and (c) to read as follows:
§1065.530 Emission test sequence.
(a) Time the start of testing as follows:
(1) Perform one of the following if you precondition the engine as described in §1065.518:
(i) For cold-start duty cycles, shut down the engine.  Unless the standard-setting part specifies that you may only perform a natural engine cooldown, you may perform a forced engine cooldown.  Use good engineering judgment to set up systems to send cooling air across the engine, to send cool oil through the engine lubrication system, to remove heat from coolant through the engine cooling system, and to remove heat from any exhaust aftertreatment systems.  In the case of a forced aftertreatment cooldown, good engineering judgment would indicate that you not start flowing cooling air until the aftertreatment system has cooled below its catalytic activation temperature.  For platinum-group metal catalysts, this temperature is about 200 °C.  Once the aftertreatment system has naturally cooled below its catalytic activation temperature, good engineering judgment would indicate that you use clean air with a temperature of at least 15 °C, and direct the air through the aftertreatment system in the normal direction of exhaust flow.  Do not use any cooling procedure that results in unrepresentative emissions (see §1065.10(c)(1)).  You may start a cold-start duty cycle when the temperatures of an engine's lubricant, coolant, and aftertreatment systems are all between (20 and 30) °C.
(ii) For hot-start emission measurements, immediately after completing the last preconditioning cycle, shut down the engine and as soon as practical start the official hot-start transient cycle.  We will start the official hot-start transient cycle within 1 minute of the conclusion of the preconditioning cycle where applicable.  Start the hot-start duty cycle as specified in the standard-setting part if it is different from this procedure.
(iii) For testing that involves hot-stabilized emission measurements, such as any steady-state testing, as soon as practical after completing the discrete-mode preconditioning time or the last preconditioning cycle, without shutting down the engine, start the official hot-stabilized cycle.  We will start the official hot-stabilized cycle within 1 minute of the conclusion of the preconditioning cycle where applicable.  If the last preconditioning cycle ends with a different operating condition than the first mode of  the hot-stabilized cycle, add a linear transition period of 20 s between cycles where you linearly ramp the (denormalized) reference speed and torque values over the transition period.
(2) If you do not precondition the engine as described in §1065.518, perform one of the following:
(i) For cold-start duty cycles, prepare the engine according to paragraph (a)(1)(i) of this section.
(ii) For hot-start emission measurements, first operate the engine at any speed above peak-torque speed and at (65 to 85) % of maximum mapped power until either the engine coolant, block, or head absolute temperature is within +-2 % of its mean value for at least 2 min or until the engine thermostat controls engine temperature.  Shut down the engine.  Start the duty cycle within 20 min of engine shutdown.
(iii) For testing that involves hot-stabilized emission measurements, bring the engine either to warm idle or the first operating point of the duty cycle.  Start the test within 10 min of achieving temperature stability.  Determine temperature stability either as the point at which the engine coolant, block, or head absolute temperature is within +-2 % of its mean value for at least 2 min, or as the point at which the engine thermostat controls engine temperature.
(b)	*	*	*
(12) Drain any accumulated condensate from the intake air system before starting a duty cycle, as described in §1065.125(e)(1).  If engine and aftertreatment preconditioning cycles are run before the duty cycle, treat the preconditioning cycles and any associated soak period as part of the duty cycle for the purpose of opening drains and draining condensate.  Note that you must close any intake air condensate drains that are not representative of those normally open during in-use operation.
(c) Start testing as follows:
(1) If engine starting is not part of the duty cycle, perform the following for the various duty cycles:
(i) Transient and steady-state ramped-modal cycles. Simultaneously start recording continuous data, any electronic integrating devices, batch sampling, and execution of the duty cycle.
(ii) Steady-state discrete-mode cycles.  Control the engine operation to match the first mode in the test cycle.  This will require controlling engine speed and load, engine load, or other operator demand settings, as specified in the standard-setting part.  Follow the instructions in the standard-setting part to determine how long to stabilize engine operation at each mode, how long to sample emissions at each mode, and how to transition between modes.  For each mode, simultaneously start recording continuous data, any electronic integrating devices, and batch sampling.
(2) If engine starting is part of the duty cycle, simultaneously start recording continuous data, any electronic integrating devices, and batch sampling  before attempting to start the engine.  Initiate the duty cycle when the engine starts.
(3) For batch sampling systems you may use good engineering judgment to advance or delay the start and stop of sampling with respect to the beginning and end of the test interval to improve the accuracy of the batch sample.
*	*	*	*	*

115.   Section 1065.545 is revised to read as follows:
§1065.545 Verification of proportional flow control for batch sampling.
For any proportional batch sample such as a bag or PM filter, demonstrate that proportional sampling was maintained using one of the following, noting that you may omit up to 5 % of the total number of data points as outliers:
(a) For any pair of flow rates, use recorded sample and total flow rates, where total flow rate means the raw exhaust flow rate for raw exhaust sampling and the dilute exhaust flow rate for CVS sampling, or their 1 Hz means with the statistical calculations in §1065.602.  Determine the standard error of the estimate, SEE, of the sample flow rate versus the total flow rate.  For each test interval, demonstrate that SEE was less than or equal to 3.5 % of the mean sample flow rate.
(b) For any pair of flow rates, use recorded sample and total flow rates, where total flow rate means the raw exhaust flow rate for raw exhaust sampling and the dilute exhaust flow rate for CVS sampling, or their 1 Hz means to demonstrate that each flow rate was constant within +-2.5 % of its respective mean or target flow rate.  You may use the following options instead of recording the respective flow rate of each type of meter:
(1) Critical-flow venturi option. For critical-flow venturis, you may use recorded venturi-inlet conditions or their 1 Hz means.  Demonstrate that the flow density at the venturi inlet was constant within +-2.5 % of the mean or target density over each test interval.  For a CVS critical-flow venturi, you may demonstrate this by showing that the absolute temperature at the venturi inlet was constant within +-4 % of the mean or target absolute temperature over each test interval.
(2) Positive-displacement pump option.  You may use recorded pump-inlet conditions or their 1 Hz means.  Demonstrate that the flow density at the pump inlet was constant within +-2.5 % of the mean or target density over each test interval.  For a CVS pump, you may demonstrate this by showing that the absolute temperature at the pump inlet was constant within +-2 % of the mean or target absolute temperature over each test interval.
(c) Using good engineering judgment, demonstrate with an engineering analysis that the proportional-flow control system inherently ensures proportional sampling under all circumstances expected during testing.  For example, you might use CFVs for both sample flow and total dilute exhaust (CVS) flow and demonstrate that they always have the same inlet pressures and temperatures and that they always operate under critical-flow conditions.

116. Section 1065.546 is amended by revising the section heading and the introductory text to read as follows:
§1065.546 Verification of minimum dilution ratio for PM batch sampling.
Use continuous flows and/or tracer gas concentrations for transient and ramped-modal cycles to verify the minimum dilution ratios for PM batch sampling as specified in §1065.140(e)(2) over the test interval.  You may use mode-average values instead of continuous measurements for discrete mode steady-state duty cycles.  Determine the minimum primary and minimum overall dilution ratios using one of the following methods (you may use a different method for each stage of dilution):
*	*	*	*	*

117.   Section 1065.550 is revised to read as follows:
§1065.550 Gas analyzer range verification and drift verification.
(a) Range verification.  If an analyzer operated above 100 % of its range at any time during the test, perform the following steps:
(1) For batch sampling, re-analyze the sample using the lowest analyzer range that results in a maximum instrument response below 100 %.  Report the result from the lowest range from which the analyzer operates below 100 % of its range.
(2) For continuous sampling, repeat the entire test using the next higher analyzer range.  If the analyzer again operates above 100 % of its range, repeat the test using the next higher range.  Continue to repeat the test until the analyzer always operates at less than 100 % of its range.
(b) Drift verification.  Gas analyzer drift verification is required for all gaseous exhaust constituents for which an emission standard applies.  It is also required for CO2 even if there is no CO2 emission standard.  It is not required for other gaseous exhaust constituents for which only a reporting requirement applies (such as CH4 and N2O).
(1) Verify drift using one of the following methods:
(i) For regulated exhaust constituents determined from the mass of a single component, perform drift verification based on the regulated constituent.  For example, when NOx mass is determined with a dry sample measured with a CLD and the removed water is corrected based on measured CO2, CO, THC, and NOx concentrations, you must verify the calculated NOx value.
(ii) For regulated exhaust constituents determined from the masses of multiple subcomponents, perform the drift verification based on either the regulated constituent or all the mass subcomponents.  For example, when NOx is measured with separate NO and NO2 analyzers, you must verify either the NOx value or both the NO and NO2 values.
(iii) For regulated exhaust constituents determined from the concentrations of multiple gaseous emission subcomponents prior to performing mass calculations, perform drift verification on the regulated constituent.  You may not verify the concentration subcomponents (e.g., THC and CH4 for NMHC) separately.  For example, for NMHC measurements, perform drift verification on NMHC; do not verify THC and CH4 separately.
(2) Drift verification requires two sets of emission calculations.  For each set of calculations, include all the constituents in the drift verification.  Calculate one set using the data before drift correction and calculate the other set after correcting all the data for drift according to §1065.672.  Note that for purposes of drift verification, you must leave unaltered any negative emission results over a given test interval (i.e., do not set them to zero).  These unaltered results are used when verifying either test interval results or composite brake-specific emissions over the entire duty cycle for drift.  For each constituent to be verified, both sets of calculations must include the following:
(i) Calculated mass (or mass rate) emission values over each test interval.
(ii) If you are verifying each test interval based on brake-specific values, calculate brake-specific emission values over each test interval.
(iii) If you are verifying over the entire duty cycle, calculate composite brake-specific emission values.
(3) The duty cycle is verified for drift if you satisfy the following criteria:
(i) For each regulated gaseous exhaust constituent, you must satisfy one of the following:
(A) For each test interval of the duty cycle, the difference between the uncorrected and the corrected brake-specific emission values of the regulated constituent must be within +-4 % of the uncorrected value or the applicable emissions standard, whichever is greater.  Alternatively, the difference between the uncorrected and the corrected emission mass (or mass rate) values of the regulated constituent must be within 4 % of the uncorrected value or the composite work (or power) multiplied by the applicable emissions standard, whichever is greater.  For purposes of verifying each test interval, you may use either the reference or actual composite work (or power).
(B) For each test interval of the duty cycle and for each mass subcomponent of the regulated constituent, the difference between the uncorrected and the corrected brake-specific emission values must be within +-4 % of the uncorrected value.  Alternatively, the difference between the uncorrected and the corrected emissions mass (or mass rate) values must be within +-4 % of the uncorrected value.
(C) For the entire duty cycle, the difference between the uncorrected and the corrected composite brake-specific emission values of the regulated constituent must be within +-4 % of the uncorrected value or applicable emission standard, whichever is greater.
(D) For the entire duty cycle and for each subcomponent of the regulated constituent, the difference between the uncorrected and the corrected composite brake-specific emission values must be within +-4 % of the uncorrected value.
(ii) Where no emission standard applies for CO2, you must satisfy one of the following:
(A) For each test interval of the duty cycle, the difference between the uncorrected and the corrected brake-specific CO2 values must be within +-4 % of the uncorrected value; or the difference between the uncorrected and the corrected CO2 mass (or mass rate) values must be within +-4 % of the uncorrected value.
(B) For the entire duty cycle, the difference between the uncorrected and the corrected composite brake-specific CO2 values must be within +-4 % of the uncorrected value.
(4) If the test is not verified for drift as described in paragraph (b)(1) of this section, you may consider the test results for the duty cycle to be valid only if, using good engineering judgment, the observed drift does not affect your ability to demonstrate compliance with the applicable emission standards.  For example, if the drift-corrected value is less than the standard by at least two times the absolute difference between the uncorrected and corrected values, you may consider the data to be verified for demonstrating compliance with the applicable standard.

Subpart G -- [Amended]
118. Section 1065.601 is amended by revising paragraph (b) to read as follows:
§1065.601 Overview.
*	*	*	*	*
(b) You may use data from multiple systems to calculate test results for a single emission test, consistent with good engineering judgment.  You may also make multiple measurements from a single batch sample, such as multiple weighings of a PM filter or multiple readings from a bag sample.  Although you may use an average of multiple measurements from a single test, you may not use test results from multiple emission tests to report emissions.  We allow weighted means where appropriate.  You may discard statistical outliers, but you must report all results.
*	*	*	*	*

119.   Section 1065.630 is revised to read as follows:
§1065.630 1980 international gravity formula.
The acceleration of Earth's gravity, ag, varies depending on your location.  Calculate ag at your latitude, as follows:
ag = 9.7803267715 ∙ [1 + 5.2790414 ∙ 10[-3]∙sin[2] () + 2.32718 ∙ 10[-5]∙sin[4] ()
+ 1.262 ∙ 10[-7]∙sin[6] () + 7 ∙ 10[-10]∙sin[8] ()]
                  Eq. 1065.630-1
Where:
 = Degrees north or south latitude.
Example:
 = 45 °
ag = 9.7803267715 ∙ (1 + 5.2790414 ∙ 10[-3]∙sin[2] (45) + 2.32718 ∙ 10[-5]∙sin[4] (45)
+ 1.262 ∙ 10[-7]∙sin[6] (45) + 7 ∙ 10[-10]∙sin[8] (45)
ag = 9.8061992026 m/s[2]

120. Section 1065.640 is amended by revising paragraphs (a), (b), and (e) to read as follows:
§1065.640 Flow meter calibration calculations.
*	*	*	*	*
(a) Reference meter conversions.  The calibration equations in this section use molar flow rate, , as a reference quantity.  If your reference meter outputs a flow rate in a different quantity, such as standard volume rate, , actual volume rate, , or mass rate,, convert your reference meter output to a molar flow rate using the following equations, noting that while values for volume rate, mass rate, pressure, temperature, and molar mass may change during an emission test, you should ensure that they are as constant as practical for each individual set point during a flow meter calibration:

                  Eq. 1065.640-1
Where:
= reference molar flow rate.
= reference volume flow rate, corrected to a standard pressure and a standard temperature.
= reference volume flow rate at the actual pressure and temperature of the flow rate.
= reference mass flow.
pstd = standard pressure.
pact = actual pressure of the flow rate.
Tstd = standard temperature.
Tact = actual temperature of the flow rate.
R = molar gas constant.
Mmix = molar mass of the flow rate.

Example 1:
= 1000.00 ft[3]/min = 0.471948 m[3]/s
pstd = 29.9213 in Hg @ 32 °F = 101325 Pa
Tstd = 68.0 °F = 293.15 K
R = 8.314472 J/(mol∙K)

= 19.619 mol/s

Example 2:
= 17.2683 kg/min = 287.805 g/s
Mmix = 28.7805 g/mol

= 10.0000 mol/s
(b) PDP calibration calculations. For each restrictor position, calculate the following values from the mean values determined in §1065.340, as follows:
(1) PDP volume pumped per revolution, Vrev (m[3]/r):

                  Eq. 1065.640-2
Example:
= 25.096 mol/s
R = 8.314472 J/(mol∙K)
= 299.5 K
= 98290 Pa
= 1205.1 r/min = 20.085 r/s

Vrev = 0.03166 m[3]/r

(2) PDP slip correction factor, Ks (s/r):

                  Eq. 1065.640-3
Example:
= 1205.1 r/min = 20.085 r/s
= 100.103 kPa
= 98.290 kPa

Ks = 0.006700 s/r
(3) Perform a least-squares regression of PDP volume pumped per revolution, Vrev, versus PDP slip correction factor, Ks, by calculating slope, a1, and intercept, a0, as described in §1065.602.
(4) Repeat the procedure in paragraphs (b)(1) through (3) of this section for every speed that you run your PDP.
(5) The following example illustrates these calculations:
Table 1 of §1065.640 -
Example of PDP calibration data

(r/min)
a1        (m[3]/min)
a0        (m[3]/r)
755.0
50.43
0.056
987.6
49.86
-0.013
1254.5
48.54
0.028
1401.3
47.30
-0.061

(6) For each speed at which you operate the PDP, use the corresponding slope, a1, and intercept, a0, to calculate flow rate during emission testing as described in §1065.642.
*	*	*	*	*
(e) CFV calibration.  Some CFV flow meters consist of a single venturi and some consist of multiple venturis, where different combinations of venturis are used to meter different flow rates.  For CFV flow meters that consist of multiple venturis, either calibrate each venturi independently to determine a separate discharge coefficient, Cd, for each venturi, or calibrate each combination of venturis as one venturi.  In the case where you calibrate a combination of venturis, use the sum of the active venturi throat areas as At, the square root of the sum of the squares of the active venturi throat diameters as dt, and the ratio of the venturi throat to inlet diameters as the ratio of the square root of the sum of the active venturi throat diameters (dt) to the diameter of the common entrance to all of the venturis (D).  To determine the Cd for a single venturi or a single combination of venturis, perform the following steps:
(1) Use the data collected at each calibration set point to calculate an individual Cd for each point using Eq. 1065.640-4.
(2) Calculate the mean and standard deviation of all the Cd values according to Eqs. 1065.602-1 and 1065.602-2.
(3) If the standard deviation of all the Cd values is less than or equal to 0.3 % of the mean Cd, use the mean Cd in Eq. 1065.642-4, and use the CFV only up to the highest r measured during calibration using the following equation:

                  Eq. 1065.640-13
Where:
pCFV = Differential static pressure; venturi inlet minus venturi outlet.
(4) If the standard deviation of all the Cd values exceeds 0.3 % of the mean Cd, omit the Cd value corresponding to the data point collected at the highest rmeasured during calibration.
(5) If the number of remaining data points is less than seven, take corrective action by checking your calibration data or repeating the calibration process.  If you repeat the calibration process, we recommend checking for leaks, applying tighter tolerances to measurements and allowing more time for flows to stabilize.
(6) If the number of remaining Cd values is seven or greater, recalculate the mean and standard deviation of the remaining Cd values.
(7) If the standard deviation of  the remaining Cd values is less than or equal to 0.3 % of the mean of the remaining Cd, use that mean Cd in Eq. 1065.642-4, and use the CFV values only up to the highest rassociated with the remaining Cd.
(8) If the standard deviation of the remaining Cd still exceeds 0.3 % of the mean of the remaining Cd values, repeat the steps in paragraph (e)(4) through (8) of this section.

121. Section 1065.642 is amended by revising paragraphs (a) and (c) to read as follows:
§1065.642 SSV, CFV, and PDP molar flow rate calculations.
*	*	*	*	*
(a) PDP molar flow rate.  Based upon the speed at which you operate the PDP for a test interval, select the corresponding slope, a1, and intercept, a0, as calculated in §1065.640, to calculate molar flow rate, as follows:

                  Eq. 1065.642-1
Where:

                  Eq. 1065.642-2

Example:
a1 = 50.43 (m[3]/min) = 0.8405 (m[3]/s)
fnPDP = 755.0 r/min = 12.58 r/s
pout = 99950 Pa
pin = 98575 Pa
a0 = 0.056 (m[3]/r)
R = 8.314472 J/(mol∙K)
Tin = 323.5 K
Cp = 1000 (J/m[3])/kPa
Ct = 60 s/min

Vrev = 0.06383 m[3]/r

= 29.428 mol/s
*	*	*	*	*
(c) CFV molar flow rate.  Some CFV flow meters consist of a single venturi and some consist of multiple venturis, where different combinations of venturis are used to meter different flow rates.  If you use multiple venturis and you calibrated each venturi independently to determine a separate discharge coefficient, Cd (or calibration coefficient, Kv), for each venturi, calculate the individual molar flow rates through each venturi and sum all their flow rates to determine.  If you use multiple venturis and you calibrated each combination of venturis, calculate using the sum of the active venturi throat areas as At, the square root of the sum of the squares of the active venturi throat diameters as dt, and the ratio of the venturi throat to inlet diameters as the ratio of the square root of the sum of the active venturi throat diameters (dt) to the diameter of the common entrance to all of the venturis (D).
(1) To calculate the molar flow rate through one venturi or one combination of venturis, use its respective mean Cd and other constants you determined according to §1065.640 and calculate its molar flow rate during an emission test, as follows:

                  Eq. 1065.642-4
Example:
Cd = 0.985
Cf = 0.7219
At = 0.00456 m[2]
pin = 98836 Pa
Z = 1
Mmix = 28.7805 g/mol = 0.0287805 kg/mol
R = 8.314472 J/(mol·K)
Tin = 378.15 K

= 33.690 mol/s
(2) To calculate the molar flow rate through one venturi or a combination of venturis, you may use its respective mean Kv and other constants you determined according to §1065.640 and calculate its molar flow rate during an emission test.  Note that if you choose to follow the permissible ranges of dilution air dewpoint versus calibration air dewpoint in Table 3 of §1065.640, you may set Mmix-cal and Mmix equal to 1. Calculate as follows:

                  Eq. 1065.642-5
Where:

                  Eq. 1065.642-6
Vstdref = volumetric flow of the standard at reference conditions of 293.15 K and 101.325 kPa.
Tin-cal = Venturi inlet temperature during calibration.
Pin-cal = Venturi inlet pressure during calibration.
Mmix-cal = Molar mass of gas mixture used during calibration.
Mmix = Molar mass of gas mixture during the emission test calculated using Equation 1065.640-9.

Example:
Vstdref = 0.4895 m[3]
Tin-cal = 302.52 K
Pin-cal = 99654 Pa
pin = 98836 Pa
pstd = 101325 Pa
Mmix-cal = 28.9656 g/mol = 0.0289656 kg/mol
Mmix = 28.7805 g/mol = 0.0287805 kg/mol
Tin = 353.15 K
Tstd = 293.15 K
R = 8.314472 J/(mol·K)

= 16.457 mol/s

122. Section 1065.645 is amended by revising the introductory text and paragraph (a) and adding paragraph (d) to read as follows:
§1065.645 Amount of water in an ideal gas.
This section describes how to determine the amount of water in an ideal gas, which you need for various performance verifications and emission calculations.  Use the equation for the vapor pressure of water in paragraph (a) of this section or another appropriate equation and, depending on whether you measure dewpoint or relative humidity, perform one of the calculations in paragraph (b) or (c) of this section.  Paragraph (d) of this section provides an equation for determining dewpoint from relative humidity and dry bulb temperature measurements.  The equations for the vapor pressure of water as presented in this section are derived from equations in "Saturation Pressure of Water on the New Kelvin Temperature Scale" (Goff, J.A., Transactions American Society of Heating and Air-Conditioning Engineers, Vol. 63, No. 1607, pages 347  -  354).  Note that the equations were originally published to derive vapor pressure in units of atmospheres and have been modified to derive results in units of kPa by converting the last term in each equation.
(a) Vapor pressure of water.  Calculate the vapor pressure of water for a given saturation temperature condition, Tsat, as follows, or use good engineering judgment to use a different relationship of the vapor pressure of water to a given saturation temperature condition:
(1) For humidity measurements made at ambient temperatures from (0 to 100) °C, or for humidity measurements made over super-cooled water at ambient temperatures from ( - 50 to 0) °C, use the following equation:
			Eq. 1065.645-1
Where:
pH20 = vapor pressure of water at saturation temperature condition, kPa.
Tsat = saturation temperature of water at measured conditions, K.

Example:
Tsat = 9.5 °C = 282.65 K

log10(pH20) = 0.074297
pH20 = 10[0.074297] = 1.186581 kPa

(2) For humidity measurements over ice at ambient temperatures from ( - 100 to 0) °C, use the following equation:

                  Eq. 1065.645-2

Example:
Tice =  - 15.4 °C = 257.75 K

log10(pH20) =  - 0.798207
pH20 = 10[ - 0.79821] = 0.159145 kPa
*	*	*	*	*
(d) Dewpoint determination from relative humidity and dry bulb temperature.  This paragraph (d) describes how to calculate dewpoint temperature from relative humidity, RH %.  This is based on "ITS-90 Formulations for Vapor Pressure, Frostpoint Temperature, Dewpoint Temperature, and Enhancement Factors in the Range  - 100 to +100 °C" (Hardy, B., The Proceedings of the Third International Symposium on Humidity & Moisture, Teddington, London, England, April 1998).  Calculate pH20sat as described in paragraph (a) of this section based on setting Tsat equal to Tamb.  Calculate pH20scaled by multiplying pH20sat by RH %.  Calculate the dewpoint, Tdew, from pH20 using the following equation:

	Eq. 1065.645-5

Where:
ln(pH20) = the natural log of pH2Oscaled, which is the water vapor pressure scaled to the relative humidity at the location of the relative humidity measurement, Tsat = Tamb.

Example:
RH % = 39.61 %
Tsat = Tamb = 20.00 °C = 293.15K
Using Eq. 1065.645-1,
pH20sat = 2.3371 kPa
pH2Oscaled = (39.61 %) = 0.925717 kPa = 925.717 Pa
Tdew = 279.00 K = 5.85 °C

123. Section 1065.650 is amended by revising paragraph (c)(1) to read as follows:
§1065.650 Emission calculations.
*	*	*	*	*
(c)	*	*	*
(1) Concentration corrections. Perform the following sequence of preliminary calculations on recorded concentrations:
(i) Correct all gaseous emission analyzer concentration readings, including continuous readings, sample bag readings, and dilution air background readings, for drift as described in §1065.672.  Note that you must omit this step where brake-specific emissions are calculated without the drift correction for performing the drift validation according to §1065.550(b).  When applying the initial THC and CH4 contamination readings according to §1065.520(f), use the same values for both sets of calculations.  You may also use as-measured values in the initial set of calculations and corrected values in the drift-corrected set of calculations as described in §1065.520(g)(7).
(ii) Correct all THC and CH4 concentrations for initial contamination as described in §1065.660(a), including continuous readings, sample bags readings, and dilution air background readings.
(iii) Correct all concentrations measured on a "dry" basis to a "wet" basis, including dilution air background concentrations, as described in §1065.659.
(iv) Calculate all NMHC and CH4 concentrations, including dilution air background concentrations, as described in §1065.660.
(v) For emission testing with an oxygenated fuel, calculate any HC concentrations, including dilution air background concentrations, as described in §1065.665.  See subpart I of this part for testing with oxygenated fuels.
(vi) Correct all the NOx concentrations, including dilution air background concentrations, for intake-air humidity as described in §1065.670.
*	*	*	*	*

124. Section 1065.655 is amended by revising paragraphs (c) introductory text, (c)(3), (d), (e), and (f)(2) to read as follows:
§1065.655 Chemical balances of fuel, intake air, and exhaust.
*	*	*	*	*
(c) Chemical balance procedure.  The calculations for a chemical balance involve a system of equations that require iteration.  We recommend using a computer to solve this system of equations.  You must guess the initial values of up to three quantities: the amount of water in the measured flow, xH2Oexh, fraction of dilution air in diluted exhaust, xdil/exh, and the amount of products on a C1 basis per dry mole of dry measured flow, xCcombdry.  You may use time-weighted mean values of combustion air humidity and dilution air humidity in the chemical balance; as long as your combustion air and dilution air humidities remain within tolerances of +-0.0025 mol/mol of their respective mean values over the test interval.  For each emission concentration, x, and amount of water, xH2Oexh, you must determine their completely dry concentrations, xdry and xH2Oexhdry. You must also use your fuel's atomic hydrogen-to-carbon ratio, , oxygen-to-carbon ratio, sulfur-to-carbon ratio, , and nitrogen-to-carbon ratio, .   You may calculate , , , and  based on measured fuel composition as described in paragraphs (d)(1) or (d)(2) of this section, or you may use default values for a given fuel as described in §1065.655(d)(3).  Use the following steps to complete a chemical balance:
*	*	*	*	*
(3) Use the following symbols and subscripts in the equations for this paragraph (c):
xdil/exh = amount of dilution gas or excess air per mole of exhaust.
xH2Oexh = amount of H2O in exhaust per mole of exhaust.
xCcombdry = amount of carbon from fuel in the exhaust per mole of dry exhaust.
xH2dry = amount of H2 in exhaust per amount of dry exhaust.
KH2Ogas = water-gas reaction equilibrium coefficient.  You may use 3.5 or calculate your own value using good engineering judgment.
xH2Oexhdry = amount of H2O in exhaust per dry mole of dry exhaust.
xprod/intdry = amount of dry stoichiometric products per dry mole of intake air.
xdil/exhdry = amount of dilution gas and/or excess air per mole of dry exhaust.
xint/exhdry = amount of intake air required to produce actual combustion products per mole of dry (raw or diluted) exhaust.
xraw/exhdry = amount of undiluted exhaust, without excess air, per mole of dry (raw or diluted) exhaust.
xO2int = amount of intake air O2 per mole of intake air.
xCO2intdry = amount of intake air CO2 per mole of dry intake air. You may use xCO2intdry = 375 umol/mol, but we recommend measuring the actual concentration in the intake air.
xH2Ointdry = amount of intake air H2O per mole of dry intake air.
xCO2int = amount of intake air CO2 per mole of intake air.
xCO2dil = amount of dilution gas CO2 per mole of dilution gas.
xCO2dildry = amount of dilution gas CO2 per mole of dry dilution gas. If you use air as diluent, you may use xCO2dildry = 375 umol/mol, but we recommend measuring the actual concentration in the intake air.
xH2Odildry = amount of dilution gas H2O per mole of dry dilution gas.
xH2Odil = amount of dilution gas H2O per mole of dilution gas.
x[emission]meas = amount of measured emission in the sample at the respective gas analyzer.
x[emission]dry = amount of emission per dry mole of dry sample.
xH2O[emission]meas = amount of H2O in sample at emission-detection location.  Measure or estimate these values according to §1065.145(e)(2).
xH2Oint = amount of H2O in the intake air, based on a humidity measurement of intake air.
 = atomic hydrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
 = atomic oxygen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
= atomic sulfur-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
= atomic nitrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
*	*	*	*	*
(d) Carbon mass fraction and fuel composition.  Determine carbon mass fraction of fuel, wc, and fuel composition represented by α, β, γ, and δ using one of the following methods:
(1) You may calculate wc as described in this paragraph (d)(1) based on measured fuel properties.  To do so, you must determine values for  and  in all cases, but you may set  and  to zero if the default value listed in Table 1 of this section is zero.  Calculate wc using the following equation:

                  Eq. 1065.655-19
Where:
wc = carbon mass fraction of fuel.
MC = molar mass of carbon.
 = atomic hydrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
MH = molar mass of hydrogen.
 = atomic oxygen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
MO = molar mass of oxygen.
= atomic sulfur-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
MS = molar mass of sulfur.
= atomic nitrogen-to-carbon ratio of the mixture of fuel(s) being combusted, weighted by molar consumption.
MN = molar mass of nitrogen.

Example:
 = 1.8
 = 0.05
= 0.0003
= 0.0001
MC = 12.0107
MH = 1.00794
MO = 15.9994
MS = 32.065
MN = 14.0067

wc = 0.8206

(2)  Determine a fuel's elemental mass fractions and values for α, β, γ, and δ as follows:
(i) For gaseous fuels, use the default values for α, β, γ, and δ in Table 1 of this section or use good engineering judgment to determine those values based on measurement.
(ii) Determine mass fractions for liquid fuels as follows:
(A) You may determine the fuel carbon and hydrogen mass fractions according to ASTM D5291 (incorporated by reference in §1065.1010).  When using ASTM D5291 to determine carbon and hydrogen mass fractions from gasoline (with or without blended ethanol), use good engineering judgment to adapt the method as appropriate.
(B) Determine oxygen mass fraction for gasoline (with or without blended ethanol) according to ASTM D5599 (incorporated by reference in §1065.1010).  For all other liquid fuels, determine the oxygen mass fraction using good engineering judgment.
(C) Determine the nitrogen mass fraction according to ASTM D4629 or ASTM D5762 (incorporated by reference in §1065.1010) for all liquid fuels.  Select the correct method based on the expected nitrogen content.
(D) Determine the sulfur mass fraction according to subpart H of this part.
(iii) For liquid fuels, use the default values for α, β, γ, and δ in Table 1 of this section, or you may determine the value for any of these parameters based on measurement.  Calculate measured values using the following equations:

			Eq. 1065.655-20

			Eq. 1065.655-21

			Eq. 1065.655-22

			Eq. 1065.655-23
Where:
wC = carbon mass fraction of fuel.
wH = hydrogen mass fraction of fuel.
wO = oxygen mass fraction of fuel.
wS = sulfur mass fraction of fuel.
wN = nitrogen mass fraction of fuel.

Example:
wC = 0.8206
wH = 0.1239
wO = 0.0547
wS = 0.00066

Table 1 of §1065.655 - Default values of , , , , and wc, for various fuels
Fuel
Atomic hydrogen,
oxygen, sulfur, and nitrogen-to-carbon ratios
CHαOβSN
Carbon mass
fraction, wc
g/g
Gasoline
CH1.85O0S0N0
0.866
E10 Gasoline
CH1.92O0.03S0N0
0.833
E15 Gasoline
CH1.95O0.05S0N0
0.817
E85 Gasoline
CH2.73O0.38S0N0
0.576
#1 Diesel
CH1.93O0S0N0
0.861
#2 Diesel
CH1.80O0S0N0
0.869
Liquefied petroleum gas
CH2.64O0S0N0
0.819
Natural gas
CH3.78 O0.016S0N0
0.747
E100 Ethanol
CH3O0.5S0N0
0.521
M100 Methanol
CH4O1S0N0
0.375
Residual fuel blends
Must be determined by measured fuel properties as described in paragraph (d)(1) of this section.

(e) Calculated raw exhaust molar flow rate from measured intake air molar flow rate or fuel mass flow rate.  You may calculate the raw exhaust molar flow rate from which you sampled emissions, , based on the measured intake air molar flow rate, , or the measured fuel mass flow rate, , and the values calculated using the chemical balance in paragraph (c) of this section.  The chemical balance must be based on raw exhaust gas concentrations.  Solve for the chemical balance in paragraph (c) of this section at the same frequency that you update and record  or .  For laboratory tests, calculating raw exhaust molar flow rate using measured fuel mass flow rate is valid only for steady-state testing.  See §1065.915(d)(5)(iv) for application to field testing.
(1) Crankcase flow rate. If engines are not subject to crankcase controls under the standard-setting part, you may calculate raw exhaust flow based on  or using one of the following:
(i) You may measure flow rate through the crankcase vent and subtract it from the calculated exhaust flow.
(ii) You may estimate flow rate through the crankcase vent by engineering analysis as long as the uncertainty in your calculation does not adversely affect your ability to show that your engines comply with applicable emission standards.
(iii) You may assume your crankcase vent flow rate is zero.
(2) Intake air molar flow rate calculation.  Calculate based on  using the following equation:

                  Eq. 1065.655-24
Where:
= raw exhaust molar flow rate from which you measured emissions.
= intake air molar flow rate including humidity in intake air.

Example:
= 3.780 mol/s
xint/exhdry = 0.69021 mol/mol
xraw/exhdry = 1.10764 mol/mol
xH20exhdry = 107.64 mmol/mol = 0.10764 mol/mol

= 6.066 mol/s
(3) Fuel mass flow rate calculation.  This calculation may be used only for steady-state laboratory testing.  See §1065.915(d)(5)(iv) for application to field testing.  Calculate based on  using the following equation:

                  Eq. 1065.655-25
Where:
= raw exhaust molar flow rate from which you measured emissions.
= fuel flow rate including humidity in intake air.

Example:
= 7.559 g/s
wc = 0.869 g/g
MC = 12.0107 g/mol
xCcombdry = 99.87 mmol/mol = 0.09987 mol/mol
xH20exhdry = 107.64 mmol/mol = 0.10764 mol/mol

= 6.066 mol/s
(f)	*	*	*
(2) Dilute exhaust and intake air molar flow rate calculation.  Calculate  as follows:

            Eq. 1065.655-26

Example:

125. Section 1065.659 is amended by revising paragraph (a) to read as follows:
§1065.659 Removed water correction.
(a) If you remove water upstream of a concentration measurement, x, correct for the removed water.  Perform this correction based on the amount of water at the concentration measurement, xH2O[emission]meas, and at the flow meter, xH2Oexh, whose flow is used to determine the mass emission rate or total mass over a test interval.  For continuous analyzers downstream of a sample dryer for transient and ramped-modal cycles, you must apply this correction on a continuous basis over the test interval, even if you use one of the options in §1065.145(e)(2) that results in a constant value for xH2O[emission]meas because xH2Oexh varies over the test interval.  For batch analyzers, determine the flow-weighted average based on the continuous xH2Oexh values determined as described in paragraph (c) of this section.  For batch analyzers, you may determine the flow-weighted average xH2Oexh based on a single value of xH2Oexh determined as described in paragraphs (c)(2) and (3) of this section, using flow-weighted average or batch concentration inputs.
*	*	*	*	*

126.   Section 1065.665 is revised to read as follows:
§1065.665 THCE and NMHCE determination.
(a) If you measured an oxygenated hydrocarbon's mass concentration, first calculate its molar concentration in the exhaust sample stream from which the sample was taken (raw or diluted exhaust), and convert this into a C1-equivalent molar concentration.  Add these C1-equivalent molar concentrations to the molar concentration of non-oxygenated total hydrocarbon (NOTHC).  The result is the molar concentration of total hydrocarbon equivalent (THCE).  Calculate THCE concentration using the following equations, noting that Eq. 1065.665-3 is required only if you need to convert your oxygenated hydrocarbon (OHC) concentration from mass to moles:

            Eq. 1065.665-1

                  Eq. 1065.665-2

                  Eq. 1065.665-3
Where:
xTHCE = The sum of the C1-equivalent concentrations of non-oxygenated hydrocarbons, alcohols, and aldehydes.
xNOTHC = The sum of the C1-equivalent concentrations of NOTHC.
xOHCi = The C1-equivalent concentration of oxygenated species i in diluted exhaust, not corrected for initial contamination.
xOHCi-init = The C1-equivalent concentration of the initial system contamination (optional) of oxygenated species i, dry-to-wet corrected.
xTHC[THC-FID]cor = The C1-equivalent response to NOTHC and all OHC in diluted exhaust, HC contamination and dry-to-wet corrected, as measured by the THC-FID.
RFOHCi[THC-FID] = The response factor of the FID to species i relative to propane on a C1-equivalent basis.
C[#] = the mean number of carbon atoms in the particular compound.
Mdexh = The molar mass of diluted exhaust as determine in §1065.340.
mdexhOHCi = The mass of oxygenated species i in dilute exhaust.
MOHCi = The C1-equivalent molecular weight of oxygenated species i.
mdexh = The mass of diluted exhaust
ndexhOHCi = The number of moles of oxygenated species i in total diluted exhaust flow.
ndexh = The total diluted exhaust flow.
(b) If we require you to determine nonmethane hydrocarbon equivalent (NMHCE), use the following equation:
xNMHCE = xTHCE  -  RFCH4[THC-FID]  xCH4
                  Eq. 1065.665-4
Where:
xNMHCE = The sum of the C1-equivalent concentrations of nonoxygenated nonmethane hydrocarbon (NONMHC), alcohols, and aldehydes.
RFCH4[THC-FID] = response factor of THC-FID to CH4.
xCH4 = concentration of CH4, HC contamination (optional) and dry-to-wet corrected, as measured by the gas chromatograph FID.
(c) The following example shows how to determine NMHCE emissions based on ethanol (C2H5OH), methanol (CH3OH), acetaldehyde (C2H4O), and formaldehyde (HCHO) as C1-equivalent molar concentrations:
xTHC[THC-FID]cor = 145.6 umol/mol
xCH4 = 18.9 umol/mol
xC2H5OH = 100.8 umol/mol
xCH3OH = 1.1 umol/mol
xC2H4O = 19.1 umol/mol
xHCHO = 1.3 umol/mol
RFCH4[THC-FID] = 1.07
RFC2H5OH[THC-FID] = 0.76
RFCH3OH[THC-FID] = 0.74
RFH2H4O[THC-FID] = 0.50
RFHCHO[THC-FID] = 0.0
xNMHCE = xTHC[THC-FID]cor  -  (xC2H5OH  RFC2H5OH[THC-FID]  + xCH3OH  RFCH3OH[THC-FID]  + xC2H4O  RFC2H4O[THC-FID]   + xHCHO  RFHCHO[THC-FID] + xC2H5OH + xCH3OH + xC2H4O + xHCHO  -  (RFCH4[THC-FID]  xCH4)
xNMHCE = 145.6  -  (100.8 0.76 + 1.1  0.74 + 19.1  0.50 + 1.3  0+ 100.8 + 1.1 + 19.1 + 1.3  -  (1.07  18.9)
xNMHCE = 160.71 umol/mol

127. Section 1065.695 is amended by revising paragraph (c)(4)(i) and adding paragraph (c)(6)(x) to read as follows:
§1065.695 Data requirements.
*	*	*	*	*
(c)	*	*	*
(4)	*	*	*
(i) Linearity verification.
*	*	*	*	*
(6)	*	*	*
(x) Number and type of preconditioning cycles.
*	*	*	*	*

Subpart H -- [Amended]
128. Section 1065.701 is amended by revising paragraphs (a), (d), and (f) to read as follows:
§1065.701 General requirements for test fuels.
(a) General.  For all emission measurements, use test fuels that meet the specifications in this subpart, unless the standard-setting part directs otherwise.  Section 1065.10(c)(1) does not apply with respect to test fuels.  Note that the standard-setting parts generally require that you design your emission controls to function properly when using commercially available fuels, even if they differ from the test fuel.  Where we specify multiple grades of a certain fuel type (such as diesel fuel with different sulfur concentrations), see the standard-setting part to determine which grade to use.
*	*	*	*	*
(d) Fuel specifications.  Specifications in this section apply as follows:
(1) Measure and calculate values as described in the appropriate reference procedure.  Record and report final values expressed to at least the same number of decimal places as the applicable limit value.  The right-most digit for each limit value is significant unless specified otherwise.  For example, for a specified distillation temperature of 60 °C, determine the test fuel's value to the nearest whole number.
(2) The fuel parameters specified in this subpart depend on measurement procedures that are incorporated by reference.  For any of these procedures, you may instead rely upon the procedures identified in 40 CFR part 80 for measuring the same parameter.  For example, we may identify different reference procedures for measuring gasoline parameters in 40 CFR 80.46.
*	*	*	*	*
(f) Service accumulation and field testing fuels.  If we do not specify a service-accumulation or field-testing fuel in the standard-setting part, use an appropriate commercially available fuel such as those meeting minimum specifications from the following table:

Table 1 of §1065.701 - Examples of service-accumulation and field-testing fuels.
Fuel category
Subcategory
Reference procedure[1]
Diesel
Light distillate and light blends with residual
ASTM D975

Middle distillate
ASTM D6985

Biodiesel (B100)
ASTM D6751
Intermediate and residual fuel
All
See §1065.705
Gasoline
Motor vehicle gasoline
ASTM D4814

Motor gasoline with ethanol concentrations up to 10 volume %.
ASTM D4814
Alcohol
Ethanol (E51-83)
ASTM D5798

Methanol (M70-M85)
ASTM D5797
Aviation fuel
Aviation gasoline
ASTM D910

Gas turbine
ASTM D1655

Jet B wide cut
ASTM D6615
Gas turbine fuel
General
ASTM D2880
[1]ASTM specifications are incorporated by reference in §1065.1010.

129. Section 1065.703 is amended by revising Table 1 to read as follows:
§1065.703 Distillate diesel fuel.
*	*	*	*	*
Table 1 of §1065.703 - Test fuel specifications for distillate diesel fuel
Property
Unit
Ultra Low
Sulfur
Low
Sulfur
High
Sulfur
Reference
Procedure[1]
Cetane Number
 --
40 - 50
40 - 50
40 - 50
ASTM D613
Distillation range:
Initial boiling point
10 pct. point
50 pct. point
90 pct. point
Endpoint
°C

171 - 204
204 - 238
243 - 282
293 - 332
321 - 366

171 - 204
204 - 238
243 - 282
293 - 332
321 - 366

171 - 204
204 - 238
243 - 282
293 - 332
321 - 366

ASTM D86
Gravity
°API
32 - 37
32 - 37
32 - 37
ASTM D4052
Total sulfur, ultra low sulfur
mg/kg
7  -  15

See 40 CFR 80.580
Total sulfur, low and high sulfur
mg/kg

300 - 500
800 - 2500
ASTM D2622or alternates as allowed under 40 CFR 80.580
Aromatics, min. (Remainder shall be paraffins, naphthenes, and olefins)
g/kg
100
100
100
ASTM D5186
Flashpoint, min.
°C
54
54
54
ASTM D93
Kinematic Viscosity
cSt
2.0 - 3.2
2.0 - 3.2
2.0 - 3.2
ASTM D445
[1]ASTM procedures are incorporated by reference in §1065.1010.  See §1065.701(d) for other allowed procedures.

130.   Section 1065.710 is revised to read as follows:
§1065.710 Gasoline.
(a) This section specifies test fuel properties for gasoline with ethanol (low-level blend only) and for gasoline without ethanol.  Note that the "fuel type" for the fuels specified in paragraphs (b) and (c) of this section is considered to be gasoline.  In contrast, fuels with higher ethanol concentrations, such as fuel containing 82 percent ethanol, are considered to be ethanol fuels rather than gasoline.  We specify some test fuel parameters that apply uniquely for low-temperature testing and for testing at altitudes above 1,219 m.  For all other testing,, use the test fuel parameters specified for general testing.  Unless the standard-setting part specifies otherwise, use the fuel specified in paragraph (c) of this section for general testing.
(b) The following specifications apply for a blended gasoline test fuel that has nominally 15 % ethanol (commonly called E15 test fuel):
(1) Prepare the blended test fuel from typical refinery gasoline blending components.  You may not use pure compounds, except as follows:
(i) You may use neat ethanol as a blendstock.
(ii) You may adjust the test fuel's vapor pressure by adding butane.
(iii) You may adjust the test fuel's benzene content by adding benzene.
(iv) You may adjust the test fuel's sulfur content by adding sulfur compounds that are representative of those found with in-use fuels.
(2) Table 1 of this section identifies limit values consistent with the units in the reference procedure for each fuel property.  These values are generally specified in international units.  Values presented in parentheses are for information only.  Table 1 follows:
Table 1 of §1065.710 - Test fuel specifications for a low-level ethanol-gasoline blend
Property
Unit
SPECIFICATION
Reference Procedure[1]

General Testing
Low-Temperature Testing
High Altitude Testing

Antiknock Index (R+M)/2
-
87.0 - 88.4[2]
87.0 Minimum
ASTM D2699 and D2700
Sensitivity (R-M)
-
7.5 Minimum
ASTM D2699 and D2700
Dry Vapor Pressure Equivalent (DVPE)[3]
kPa (psi)
60.0-63.4
(8.7-9.2)
77.2-81.4
(11.2-11.8)
52.4-55.2
(7.6-8.0)
ASTM D5191
Distillation
10% evaporated
°C (°F)
49-60
 (120-140)
43-54
(110-130)
49-60
 (120-140)
ASTM D86
50% evaporated
°C (°F)
77-88 (170-190)

90% evaporated
°C (°F)
154-166 (310-330)

Evaporated final boiling point
°C (°F)
193-216 (380-420)

Residue
milliliter
2.0 Maximum

Total Aromatic Hydrocarbons
volume %
19.5-24.5
ASTM D5769
C6 Aromatics (benzene)
volume %
0.6-0.8

C7 Aromatics (toluene)
volume %
4.4-5.5

C8 Aromatics
volume %
5.5-6.9

C9 Aromatics
volume %
5.0-6.2

C10+ Aromatics
volume %
4.0-5.0

Olefins[4]
mass %
4.5-11.5
ASTM D6550
Ethanol blended[5]
volume %
14.6-15.0
See paragraph (b)(3) of this section.
Ethanol confirmatory[6,7]
volume %
14.3-15.3
ASTM D5599
Total Content of Oxygenates Other than Ethanol[7]
volume %
0.1 Maximum
ASTM D5599
Sulfur
mg/kg
8.0-11.0
ASTM D2622, D5453 or D7039
Lead
g/liter
0.0026 Maximum
ASTM D3237
Phosphorus
g/liter
0.0013 Maximum
ASTM D3231
Copper Corrosion
-
No. 1 Maximum
ASTM D130
Solvent-Washed Gum Content
mg/100 milliliter
3.0 Maximum
ASTM D381
Oxidation Stability
minute
1000 Minimum
ASTM D525
[1]ASTM procedures are incorporated by reference in §1065.1010. See §1065.701(d) for other allowed procedures.
[2]Octane specifications apply only for testing related to exhaust emissions.  For engines or vehicles that require the use of premium fuel, as described in paragraph (d) of this section, the adjusted specification for antiknock index is a minimum value of 91.0; no maximum value applies.  All other specifications apply for this high-octane fuel.
[3]Calculate dry vapor pressure equivalent, DVPE, based on the measured total vapor pressure, pT, in kPa using the following equation: DVPE = 0.956∙pT - 2.39.  DVPE is intended to be equivalent to Reid Vapor Pressure using a different test method.
[4]The specified olefin concentration range equates to approximately 4  -  10 volume % when measured according to ASTM D1319.
5The ethanol blended specification is based on the volume % ethanol content of the fuel as determined during blending by the fuel supplier and as stated by the supplier at the time of fuel delivery.
[6]The ethanol confirmatory specification is based on the volume % ethanol as measured according to ASTM D5599.
[7]The reference procedure prescribes measurement of ethanol concentration in mass %.  Convert results to volume % as specified in ASTM D4815.

(3) Use good engineering judgment to determine the volume % of ethanol based on the volume of each blendstock.  We recommend using a flow-based or gravimetric procedure that has an accuracy and repeatability of +- 0.1 %.
(c) The specifications of this paragraph (c) apply for testing with neat gasoline.  This is sometimes called indolene or E0 test fuel.  Gasoline for testing must have octane values that represent commercially available fuels for the appropriate application.  Test fuel specifications apply as follows:

Table 2 of §1065.710 - Test fuel specifications for neat (E0) gasoline
Property
Unit
SPECIFICATION
Reference Procedure[1]

General Testing
Low-Temperature Testing

Distillation Range:
Evaporated initial boiling point
10% evaporated
50% evaporated
90% evaporated
Evaporated final boiling point
°C

24 - 35 2
49 - 57
93 - 110
149 - 163
Maximum, 213

24 - 36
37 - 48
82 - 101
158 - 174
Maximum, 212
ASTM D86

Hydrocarbon composition:
Olefins
Aromatics
Saturates
volume %

Maximum, 0.10
Maximum, 0.35
Remainder

Maximum, 0.175
Maximum, 0.304
Remainder
ASTM D1319

Lead
g/liter
Maximum, 0.013
Maximum, 0.013
ASTM D3237
Phosphorous
g/liter
Maximum, 0.0013
Maximum, 0.005
ASTM D3231
Total sulfur
mg/kg
Maximum, 80
Maximum, 80
ASTM D2622
Dry vapor pressure equivalent[2]
kPa
60.0 - 63.4[3,4]
77.2 - 81.4
ASTM D5191
[1]ASTM procedures are incorporated by reference in §1065.1010.  See §1065.701(d) for other allowed procedures.
[2]Calculate dry vapor pressure equivalent, DVPE, based on the measured total vapor pressure, pT, in kPa using the following equation: DVPE = 0.956∙pT - 2.39.  DVPE is intended to be equivalent to Reid Vapor Pressure using a different test method.
[3]For testing at altitudes above 1 219 m, the specified volatility range is (52.0 to 55.2) kPa and the specified initial boiling point range is (23.9 to 40.6) °C.
4For testing unrelated to evaporative emissions, the specified range is (55.2 to 63.4) kPa.

(d) Use the high-octane gasoline specified in paragraph (b) of this section only for engines or vehicles for which the manufacturer conditions the warranty on the use of premium gasoline.

131. Section 1065.715 is amended by revising paragraph (a) to read as follows:
§1065.715 Natural gas.
(a) Except as specified in paragraph (b) of this section, natural gas for testing must meet the specifications in the following table:
Table 1 of §1065.715 - Test fuel specifications for natural gas
Property
Value[1]
Methane, CH4
Minimum, 0.87 mol/mol
Ethane, C2H6
Maximum, 0.055 mol/mol
Propane, C3H8
Maximum, 0.012 mol/mol
Butane, C4H10
Maximum, 0.0035 mol/mol
Pentane, C5H12
Maximum, 0.0013 mol/mol
C6 and higher
Maximum, 0.001 mol/mol
Oxygen
Maximum, 0.001 mol/mol
Inert gases (sum of CO2 and N2)
Maximum, 0.051 mol/mol
[1] Demonstrate compliance with fuel specifications based on the reference procedures in ASTM D1945 (incorporated by reference in §1065.1010), or on other measurement procedures using good engineering judgment.  See §1065.701(d) for other allowed procedures.
*	*	*	*	*

132. Section 1065.720 is amended by revising paragraph (a) to read as follows:
§1065.720 Liquefied petroleum gas.
(a) Except as specified in paragraph (b) of this section, liquefied petroleum gas for testing must meet the specifications in the following table:
Table 1 of §1065.720 - Test fuel specifications for liquefied petroleum gas
Property
Value
Reference Procedure[1]
Propane, C3H8
Minimum, 0.85 m[3]/m[3]
ASTM D2163
Vapor pressure at 38 °C
Maximum, 1400 kPa
ASTM D1267or 2598[2]
Volatility residue (evaporated temperature, 35 °C)
Maximum, -38 °C
ASTM D1837
Butanes
Maximum, 0.05 m[3]/m[3]
ASTM D2163
Butenes
Maximum, 0.02 m[3]/m[3]
ASTM D2163
Pentenes and heavier
Maximum, 0.005 m[3]/m[3]
ASTM D2163
Propene
Maximum, 0.1 m[3]/m[3]
ASTM D2163
Residual matter (residue on evap. of 100) ml oil stain observ.)
Maximum, 0.05 ml pass[3]
ASTM D2158
Corrosion, copper strip
Maximum, No. 1
ASTM D1838
Sulfur
Maximum, 80 mg/kg
ASTM D2784
Moisture content
pass
ASTM D2713
[1]ASTM procedures are incorporated by reference in §1065.1010.  See §1065.701(d) for other allowed procedures.
[2]If these two test methods yield different results, use the results from ASTM D1267.
[3]The test fuel must not yield a persistent oil ring when you add 0.3 ml of solvent residue mixture to a filter paper in 0.1 ml increments and examine it in daylight after two minutes.

*	*	*	*	*

133.   A new §1065.725 is added to subpart H to read as follows:
--------------------------------------------------------------------------------
§1065.725 High-level ethanol-gasoline blends.
--------------------------------------------------------------------------------
For testing ethanol-fueled vehicles, create a high-level ethanol-gasoline blend test fuel as follows:
--------------------------------------------------------------------------------
(a) Add ethanol to an E15 fuel meeting the specifications described in §1065.710 until the ethanol content of the blended fuel is between 80 and 83 volume %.
--------------------------------------------------------------------------------
(b) You may alternatively add ethanol to a gasoline base fuel with no ethanol if you can demonstrate that such a base fuel blended with the proper amount of ethanol would meet all the specifications for E15 test fuel described in §1065.710, other than the ethanol content.
--------------------------------------------------------------------------------
(c) The ethanol used for blending must be either denatured ethanol meeting the specifications in 40 CFR 80.1510, or fuel-grade ethanol with no denaturant.  Be sure to account for the volume of any denaturant when calculating volumetric percentages.
(d) The blended test fuel must have a dry vapor pressure equivalent between 6.0 and 6.5 when measured using the procedure specified in §1065.710.  You may add commercial grade butane as needed to meet this specification.

134. Section 1065.750 is amended by revising the introductory text and paragraphs (a)(1), (a)(2), (a)(3), and (a)(5) to read as follows:
§1065.750 Analytical Gases.
Analytical gases must meet the accuracy and purity specifications of this section, unless you can show that other specifications would not affect your ability to show that you comply with all applicable emission standards.
(a)	*	*	*
(1) Use purified gases to zero measurement instruments and to blend with calibration gases.  Use gases with contamination no higher than the highest of the following values in the gas cylinder or at the outlet of a zero-gas generator:
(i) 2 % contamination, measured relative to the flow-weighted mean concentration expected at the standard.  For example, if you would expect a flow-weighted CO concentration of 100.0 mol/mol, then you would be allowed to use a zero gas with CO contamination less than or equal to 2.000 mol/mol.
(ii) Contamination as specified in the following table:

Table 1 of §1065.750 - General specifications for purified gases[1]
Constituent
Purified Air
Purified N2
THC (C1 equivalent)
<= 0.05 mol/mol
<= 0.05 mol/mol
CO
<= 1 mol/mol
<= 1 mol/mol
CO2
<= 10 mol/mol
<= 10 mol/mol
O2
0.205 to 0.215 mol/mol
<= 2 mol/mol
NOx
<= 0.02 mol/mol
<= 0.02 mol/mol
N2O[2]
<= 0.02 mol/mol
<= 0.02 mol/mol
[1]We do not require these levels of purity to be NIST-traceable.
[2]The N2O limit applies only if the standard-setting part requires you to report N2O or certify to an N2O standard.

(2) Use the following gases with a FID analyzer:
(i) FID fuel. Use FID fuel with a stated H2 concentration of (0.39 to 0.41) mol/mol, balance He or N2, and a stated total hydrocarbon concentration of 0.05 mol/mol or less.  For GC-FIDs that measure methane (CH4) using a FID fuel that is balance N2, perform the CH4 measurement as described in SAE J1151 (incorporated by reference in §1065.1010).
(ii) FID burner air. Use FID burner air that meets the specifications of purified air in paragraph (a)(1) of this section.  For field testing, you may use ambient air.
(iii) FID zero gas.  Zero flame-ionization detectors with purified gas that meets the specifications in paragraph (a)(1) of this section, except that the purified gas O2 concentration may be any value.  Note that FID zero balance gases may be any combination of purified air and purified nitrogen.  We recommend FID analyzer zero gases that contain approximately the expected flow-weighted mean concentration of O2 in the exhaust sample during testing.
(iv) FID propane span gas.  Span and calibrate THC FID with span concentrations of propane, C3H8.  Calibrate on a carbon number basis of one (C1).  For example, if you use a C3H8 span gas of concentration 200 mol/mol, span a FID to respond with a value of 600 mol/mol.  Note that FID span balance gases may be any combination of purified air and purified nitrogen.  We recommend FID analyzer span gases that contain approximately the flow-weighted mean concentration of O2 expected during testing.  If the expected O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen.
(v) FID CH4 span gas.  If you always span and calibrate a CH4 FID with a nonmethane cutter, then span and calibrate the FID with span concentrations of CH4. Calibrate on a carbon number basis of one (C1).  For example, if you use a CH4 span gas of concentration 200 mol/mol, span a FID to respond with a value of 200 mol/mol.  Note that FID span balance gases may be any combination of purified air and purified nitrogen.  We recommend FID analyzer span gases that contain approximately the expected flow-weighted mean concentration of O2 in the exhaust sample during testing.  If the expected O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen.
(3) Use the following gas mixtures, with gases traceable within +-1 % of the NIST-accepted value or other gas standards we approve:
(i) CH4, balance purified air and/or N2 (as applicable).
(ii) C2H6, balance purified air and/or N2 (as applicable).
(iii) C3H8, balance purified air and/or N2 (as applicable).
(iv) CO, balance purified N2.
(v) CO2, balance purified N2.
(vi) NO, balance purified N2.
(vii)) NO2, balance purified air.
(viii) O2, balance purified N2.
(ix) C3H8, CO, CO2, NO, balance purified N2.
(x) C3H8, CH4, CO, CO2, NO, balance purified N2.
(xi) N2O, balance purified air and/or N2 (as applicable).
*	*	*	*	*
(5) You may generate your own calibration gases using a precision blending device, such as a gas divider, to dilute gases with purified N2 or purified air.  If your gas divider meets the specifications in §1065.248, and the gases being blended meet the requirements of paragraphs (a)(1) and (3) of this section, the resulting blends are considered to meet the requirements of this paragraph (a).
*	*	*	*	*

Subpart I -- [Amended]
135. Section 1065.805 is amended by revising paragraphs (d) and (f) to read as follows:
§1065.805 Sampling system.
*	*	*	*	*
(d) You may bubble a sample of the exhaust through water to collect alcohols for later analysis.  You may also use a photo-acoustic analyzer to quantify ethanol and methanol in an exhaust sample as described in §1065.269.
*	*	*	*	*
(f)  You may sample alcohols or carbonyls using "California Non-Methane Organic Gas Test Procedures" (incorporated by reference in §1065.1010).  If you use this method, follow its calculations to determine the mass of the alcohol/carbonyl in the exhaust sample, but follow subpart G of this part for all other calculations (40 CFR part 1066, subpart G, for vehicle testing).
*	*	*	*	*

136.   Section 1065.845 is amended by redesignating paragraphs (a) and (b) as paragraphs (b) and (c), respectively, and adding a new paragraph (a) to read as follows:
§1065.845 Response factor determination.
Since FID analyzers generally have an incomplete response to alcohols and carbonyls, determine each FID analyzer's alcohol/carbonyl response factor (such as RFMeOH) after FID optimization to subtract those responses from the FID reading.  Use the most recently determined alcohol/carbonyl response factors to compensate for alcohol/carbonyl response.  You are not required to determine the response factor for a compound unless you will subtract its response to compensate for a response.
(a) You may generate response factors as described in paragraph (b) of this section, or you may use the following default response factors, consistent with good engineering judgment:
Table 1 of §1065.665 - Default values for THC FID
response factor relative to propane on a C1-equivalent basis
Compound
Response factor (RF)
acetaldehyde
0.50
ethanol
0.75
formaldehyde
0.00
methanol
0.63
propanol
0.85
*	*	*	*	*

137.   Section 1065.850 is revised to read as follows:
§1065.850 Calculations.
Use the calculations specified in §1065.665 to determine THCE or NMHCE and the calculations specified in 40 CFR 1066.665 to determine NMOG.

Subpart K -- [Amended]
138.   Section 1065.1001 is amended by removing the definition for "Engine" and revising the definitions for "C1 equivalent (or basis)", "Oxygenated fuels", and "Precision" to read as follows:
§1065.1001 Definitions.
*	*	*	*	*
	C1 equivalent (or basis) means a convention of expressing HC concentrations based on the total number of carbon atoms present, such that the C1 equivalent of a molar HC concentration equals the molar concentration multiplied by the mean number of carbon atoms in each HC molecule.  For example, the C1 equivalent of 10 mol/mol of propane (C3H8) is 30 mol/mol.  C1 equivalent molar values may be denoted as "ppmC" in the standard-setting part.  Molar mass may also be expressed on a C1 basis.  Note that calculating HC masses from molar concentrations and molar masses is only valid where they are each expressed on the same carbon basis.
*	*	*	*	*
	Oxygenated fuels means fuels composed of at least 25 % oxygen-containing compounds, such as ethanol or methanol.  Testing engines that use oxygenated fuels generally requires the use of the sampling methods in subpart I of this part.  However, you should read the standard-setting part and subpart I of this part to determine appropriate sampling methods.
*	*	*	*	*
	Precision means two times the standard deviation of a set of measured values of a single zero or reference quantity.  See also the related definitions of noise and repeatability in this section.
*	*	*	*	*

139. Section 1065.1005 is amended by revising paragraphs (a) and (f)(2) to read as follows:
§1065.1005 Symbols, abbreviations, acronyms, and units of measure.
*	*	*	*	*
(a) Symbols for quantities.  This part uses the following symbols and units of measure for various quantities:
Symbol
Quantity
Unit
Unit symbol
Units in terms of SI base units

atomic hydrogen to carbon ratio
mole per mole
mol/mol
1
A
area
square meter
m[2]
m[2]
A0
intercept of least squares regression

A1
slope of least squares  regression


ratio of diameters
meter per meter
m/m
1

atomic oxygen to carbon ratio
mole per mole
mol/mol
1
C#
number of carbon atoms in a molecule

d
Diameter
meter
m
m
DR
dilution ratio
mole per mol
mol/mol
1

error between a quantity and its reference

e
brake-specific emission or fuel consumption
gram per kilowatt hour
g/(kW∙hr)
g∙3.6[-1]∙10[6]∙m[-2]∙kg∙s[2]
F
F-test statistic

f
frequency
hertz
Hz
s[-1]
fn
angular speed (shaft)
revolutions per minute
r/min
2∙PI∙60[-1]∙m·m[-1]·s[-1]

ratio of specific heats
(joule per kilogram kelvin) per (joule per kilogram kelvin)
(J/(kg∙K))/(J/(kg∙K))
1
K
correction factor

1
Kv
calibration coefficient

m[4]∙s∙K[0.5]/kg
m[4]∙s∙K[0.5]∙kg[-1]
l
length
meter
m
m

viscosity, dynamic
pascal second
Pa∙s
m[-1]∙kg∙s[-1]
M
molar mass[1]
gram per mole
g/mol
10[-3]∙kg∙mol[-1]
m
mass
kilogram
kg
kg
\s \* MERGEFORMAT
mass rate
kilogram per second
kg/s
kg∙s[-1]

viscosity, kinematic
meter squared per second
m[2]/s
m[2]∙s[-1]
N
total number in series

n
amount of substance
mole
mol
mol
\s \* MERGEFORMAT
amount of substance rate
mole per second
mol/s
mol∙s[-1]
P
power
kilowatt
kW
10[3]∙m[2]∙kg∙s[-3]
PF
penetration fraction

p
pressure
pascal
Pa
m[-1]∙kg∙s[-2]

mass density
kilogram per cubic meter
kg/m[3]
kg∙m[-3]
r
ratio of pressures
pascal per pascal
Pa/Pa
1
R[2]
coefficient of determination

Ra
average surface roughness
micrometer
m
10[-6] m
Re[#]
Reynolds number

RF
response factor

RH
relative humidity


non-biased standard deviation

S
Sutherland constant
kelvin
K
K
SEE
standard estimate of error

T
absolute temperature
kelvin
K
K
T
Celsius temperature
degree Celsius
°C
K-273.15
T
torque (moment of force)
newton meter
N∙m
m[2]∙kg∙s[-2]
t
time
second
s
s
t
time interval, period, 1/frequency
second
s
s
V
volume
cubic meter
m[3]
m[3]
\s \* MERGEFORMAT
volume rate
cubic meter per second
m[3]/s
m[3]∙s[-1]
W
work
kilowatt hour
kW∙hr
3.6∙10[-6]∙m[2]∙kg∙s[-2]
wc
carbon mass fraction
gram per gram
g/g
1
x
amount of substance mole fraction [2]
mole per mole
mol/mol
1
\s \* MERGEFORMAT
flow-weighted mean concentration
mole per mole
mol/mol
1
y
generic variable

[1] See paragraph (f)(2) of this section for the values to use for molar masses.  Note that in the cases of NOx and HC, the regulations specify effective molar masses based on assumed speciation rather than actual speciation.
2 Note that mole fractions for THC, THCE, NMHC, NMHCE, and NOTHC are expressed on a C1 equivalent basis.

[NOTE TO EDITOR: The current CFR has incorrect rendering of \s \* MERGEFORMAT and \s \* MERGEFORMAT and \s \* MERGEFORMAT.  Please make sure the final published characters are properly displayed.  Also, all the symbols in the first column should be in italic font (except the subscripts); this is also incorrect for the Greek letters in the current CFR.]
*	*	*	*	*
(f)	*	*	*
   (2) This part uses the following molar masses or effective molar masses of chemical species:
Symbol
Quantity
g/mol
(10[-3]·kg·mol[-1])
Mair
molar mass of dry air[1]
28.96559
MAr
molar mass of argon
39.948
MC
molar mass of carbon
12.0107
MCH3OH
molar mass of methanol
32.04186
MC2H5OH
molar mass of ethanol
46.06844
MC2H4O
molar mass of acetaldehyde
44.05256
MC3H8
molar mass of propane
44.09562
MC3H7OH
molar mass of propanol
60.09502
MCO
molar mass of carbon monoxide
28.0101
MCH4
molar mass of methane
16.0425
MCO2
molar mass of carbon dioxide
44.0095
MH
molar mass of atomic hydrogen
1.00794
MH2
molar mass of molecular hydrogen
2.01588
MH2O
molar mass of water
18.01528
MHCHO
molar mass of formaldehyde
30.02598
MHe
molar mass of helium
4.002602
MN
molar mass of atomic nitrogen
14.0067
MN2
molar mass of molecular nitrogen
28.0134
MNH3
molar mass of ammonia
17.03052
MNMHC
effective C1 molar mass of nonmethane hydrocarbon[2]
13.875389
MNMHCE
effective C1 molar mass of nonmethane hydrocarbon equivalent[2]
13.875389
MNOx
effective molar mass of oxides of nitrogen[3]
46.0055
MN2O
molar mass of nitrous oxide
44.0128
MO
molar mass of atomic oxygen
15.9994
MO2
molar mass of molecular oxygen
31.9988
MS
molar mass of sulfur
32.065
MTHC
effective C1 molar mass of total hydrocarbon[2]
13.875389
MTHCE