Title 40—Protection of Environment--Volume 1
PART 1065—ENGINE-TESTING PROCEDURES
§ 1065.307   Linearity verification.
(a) Scope and frequency. Perform linearity verification on each measurement system listed in Table 1 of this section at least as frequently as indicated in Table 1 of § 1065.303, consistent with measurement system manufacturer's recommendations and good engineering judgment. The intent of linearity verification is to determine that a measurement system responds accurately and proportionally over the measurement range of interest. Linearity verification generally consists of introducing a series of at least 10 reference values to a measurement system. The measurement system quantifies each reference value. The measured values are then collectively compared to the reference values by using a least-squares linear regression and the linearity criteria specified in Table 1 of this section.
(b) Performance requirements. If a measurement system does not meet the applicable linearity criteria referenced in Table 1 of this section, correct the deficiency by re-calibrating, servicing, or replacing components as needed. Repeat the linearity verification after correcting the deficiency to ensure that the measurement system meets the linearity criteria. Before you may use a measurement system that does not meet linearity criteria, you must demonstrate to us that the deficiency does not adversely affect your ability to demonstrate compliance with the applicable standards in this chapter.
(c) Procedure. Use the following linearity verification protocol, or use good engineering judgment to develop a different protocol that satisfies the intent of this section, as described in paragraph (a) of this section:
(1) In this paragraph (c), the letter “y” denotes a generic measured quantity, the superscript over-bar denotes an arithmetic mean (such as y ), and the subscript “ ref ” denotes the known or reference quantity being measured.
(2) Use good engineering judgment to operate a measurement system at normal operating conditions. This may include any specified adjustment or periodic calibration of the measurement system.
(3) If applicable, zero the instrument as you would before an emission test by introducing a zero signal. Depending on the instrument, this may be a zero-concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a zero gas that meets the specifications of § 1065.750 and introduce it directly at the analyzer port.
(4) If applicable, span the instrument as you would before an emission test by introducing a span signal. Depending on the instrument, this may be a span-concentration gas, a reference signal, a set of reference thermodynamic conditions, or some combination of these. For gas analyzers, use a span gas that meets the specifications of § 1065.750 and introduce it directly at the analyzer port.
(5) If applicable, after spanning the instrument, check zero with the same signal you used in paragraph (c)(3) of this section. Based on the zero reading, use good engineering judgment to determine whether or not to rezero and or re-span the instrument before continuing.
(6) For all measured quantities, use the instrument manufacturer's recommendations and good engineering judgment to select reference values, y refi , that cover a range of values that you expect would prevent extrapolation beyond these values during emission testing. We recommend selecting a zero reference signal as one of the reference values for the linearity verification. For pressure, temperature, dewpoint, power, current, voltage, photoacoustic analyzers, and GC-ECD linearity verifications, we recommend at least three reference values. For all other linearity verifications select at least ten reference values.
(7) Use the instrument manufacturer's recommendations and good engineering judgment to select the order in which you will introduce the series of reference values. For example, you may select the reference values randomly to avoid correlation with previous measurements and to avoid hysteresis; you may select reference values in ascending or descending order to avoid long settling times of reference signals; or you may select values to ascend and then descend to incorporate the effects of any instrument hysteresis into the linearity verification.
(8) Generate reference quantities as described in paragraph (d) of this section. For gas analyzers, use gas concentrations known to be within the specifications of § 1065.750 and introduce them directly at the analyzer port.
(9) Introduce a reference signal to the measurement instrument.
(10) Allow time for the instrument to stabilize while it measures the value at the reference condition. Stabilization time may include time to purge an instrument and time to account for its response.
(11) At a recording frequency of at least f Hz, specified in Table 1 of § 1065.205, measure the value at the reference condition for 30 seconds (you may select a longer sampling period if the recording update frequency is less than 0.5 Hz) and record the arithmetic mean of the recorded values, y i . Refer to § 1065.602 for an example of calculating an arithmetic mean.
(12) Repeat the steps in paragraphs (c)(9) though (11) of this section until measurements are complete at each of the reference conditions.
(13) Use the arithmetic means, y i , and reference values, y refi , to calculate least-squares linear regression parameters and statistical values to compare to the minimum performance criteria specified in Table 1 of this section. Use the calculations for a floating intercept described in § 1065.602. Using good engineering judgment, you may weight the results of individual data pairs ( i.e., ( y refi , y i )), in the linear regression calculations.
(d) Reference signals. This paragraph (d) describes recommended methods for generating reference values for the linearity-verification protocol in paragraph (c) of this section. Use reference values that simulate actual values, or introduce an actual value and measure it with a reference-measurement system. In the latter case, the reference value is the value reported by the reference-measurement system. Reference values and reference-measurement systems must be NIST-traceable. We recommend using calibration reference quantities that are NIST-traceable within ±0.5% uncertainty, if not specified elsewhere in this part 1065. Use the following recommended methods to generate reference values or use good engineering judgment to select a different reference:
(1) Speed. Run the engine or dynamometer at a series of steady-state speeds and use a strobe, photo tachometer, or laser tachometer to record reference speeds.
(2) Torque. Use a series of calibration weights and a calibration lever arm to simulate engine torque. You may instead use the engine or dynamometer itself to generate a nominal torque that is measured by a reference load cell or proving ring in series with the torque-measurement system. In this case, use the reference load cell measurement as the reference value. Refer to § 1065.310 for a torque-calibration procedure similar to the linearity verification in this section.
(3) Electrical power, current, and voltage. You must perform linearity verification for either electrical power meters, or for current and voltage meters. Perform linearity verifications using a reference meter and controlled sources of current and voltage. We recommend using a complete calibration system that is suitable for the electrical power distribution industry.
(4) Fuel and DEF mass flow rate . Use a gravimetric reference measurement (such as a scale, balance, or mass comparator) and a container. Use a stopwatch or timer to measure the time intervals over which reference masses of fluid pass through the mass flow rate meter. Use good engineering judgment to correct the reference mass flowing through the mass flow rate meter for buoyancy effects from any tubes, temperature probes, or objects submerged in the fluid in the container that are not attached to the container. If the container has any tubes or wires connected to the container, recalibrate the gravimetric reference measurement device with them connected and at normal operating pressure using calibration weights that meet the requirements in § 1065.790. The corrected reference mass that flowed through the mass flow rate meter during a time interval divided by the duration of the time interval is the average reference mass flow rate. For meters that report a different quantity (such as actual volume, standard volume, or moles), convert the reported quantity to mass. For meters that report a cumulative quantity calculate the average measured mass flow rate as the difference in the reported cumulative mass during the time interval divided by the duration of the time interval. For measuring flow rate of gaseous fuel prevent condensation on the fuel container and any attached tubes, fittings, or regulators.
(5) Flow rates—inlet air, dilution air, diluted exhaust, raw exhaust, or sample flow. Use a reference flow meter with a blower or pump to simulate flow rates. Use a restrictor, diverter valve, a variable-speed blower or a variable-speed pump to control the range of flow rates. Use the reference meter's response as the reference values.
(i) Reference flow meters. Because the flow range requirements for these various flows are large, we allow a variety of reference meters. For example, for diluted exhaust flow for a full-flow dilution system, we recommend a reference subsonic venturi flow meter with a restrictor valve and a blower to simulate flow rates. For inlet air, dilution air, diluted exhaust for partial-flow dilution, raw exhaust, or sample flow, we allow reference meters such as critical flow orifices, critical flow venturis, laminar flow elements, master mass flow standards, or Roots meters. Make sure the reference meter is calibrated and its calibration is NIST-traceable. If you use the difference of two flow measurements to determine a net flow rate, you may use one of the measurements as a reference for the other.
(ii) Reference flow values. Because the reference flow is not absolutely constant, sample and record values of n refi for 30 seconds and use the arithmetic mean of the values, n ref , as the reference value. Refer to § 1065.602 for an example of calculating arithmetic mean.
(6) Gas division. Use one of the two reference signals:
(i) At the outlet of the gas-division system, connect a gas analyzer that meets the linearity verification described in this section and has not been linearized with the gas divider being verified. For example, verify the linearity of an analyzer using a series of reference analytical gases directly from compressed gas cylinders that meet the specifications of § 1065.750. We recommend using a FID analyzer or a PMD or MPD O 2 analyzer because of their inherent linearity. Operate this analyzer consistent with how you would operate it during an emission test. Connect a span gas containing only a single constituent of interest with balance of purified air or purified N 2 to the gas-divider inlet. Use the gas-division system to divide the span gas with purified air or nitrogen. Select gas divisions that you typically use. Use a selected gas division as the measured value. Use the analyzer response divided by the span gas concentration as the reference gas-division value. Because the instrument response is not absolutely constant, sample and record values of x refi for 30 seconds and use the arithmetic mean of the values, x ref , as the reference value. Refer to § 1065.602 for an example of calculating arithmetic mean.
(ii) Using good engineering judgment and the gas divider manufacturer's recommendations, use one or more reference flow meters to measure the flow rates of the gas divider and verify the gas-division value.
(7) Continuous constituent concentration. For reference values, use a series of gas cylinders of known gas concentration containing only a single constituent of interest with balance of purified air or purified N 2 or use a gas-division system that is known to be linear with a span gas. Gas cylinders, gas-division systems, and span gases that you use for reference values must meet the specifications of § 1065.750.
(8) Temperature. You may perform the 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 T max . If you use this option, you must use sensors that the supplier states are accurate to better than 0.5% of T max compared with their standard calibration curve.
(9) Mass . For linearity verification for gravimetric PM balances, fuel mass scales, and DEF mass scales, use external calibration weights that meet the requirements in § 1065.790. Perform the linearity verification for fuel mass scales and DEF mass scales with the in-use container, installing all objects that interface with the container. For example, this includes all tubes, temperature probes, and objects submerged in the fluid in the container; it also includes tubes, fittings, regulators, and wires, and any other objects attached to the container. We recommend that you develop and apply appropriate buoyancy corrections for the configuration of your mass scale during normal testing, consistent with good engineering judgment. Account for the scale weighing a calibration weight instead of fluid if you calculate buoyancy corrections. You may also correct for the effect of natural convection currents from temperature differences between the container and ambient air. Prepare for linearity verification by taking the following steps for vented and unvented containers:
(i) If the container is vented to ambient, fill the container and tubes with fluid above the minimum level used to trigger a fill operation; drain the fluid down to the minimum level; tare the scale; and perform the linearity verification.
(ii) If the container is rigid and not vented, drain the fluid down to the minimum level; fill all tubes attached to the container to normal operating pressure; tare the scale; and perform the linearity verification.
(e) Measurement systems that require linearity verification. Table 1 of this section indicates measurement systems that require linearity verification, subject to the following provisions:
(1) Perform linearity verification more frequently based on the instrument manufacturer's recommendation or good engineering judgment.
(2) The expression “ x min ” refers to the reference value used during linearity verification that is closest to zero. This is the value used to calculate the first tolerance in Table 1 of this section using the intercept, a 0 . Note that this value may be zero, positive, or negative depending on the reference values. For example, if the reference values chosen to validate a pressure transducer vary from −10 to −1 kPa, x min is −1 kPa. If the reference values used to validate a temperature device vary from 290 to 390 K, x min is 290 K.
(3) The expression “max” generally refers to the absolute value of the reference value used during linearity verification that is furthest from zero. This is the value used to scale the first and third tolerances in Table 1 of this section using a 0 and SEE . For example, if the reference values chosen to validate a pressure transducer vary from −10 to −1 kPa, then p max is +10 kPa. If the reference values used to validate a temperature device vary from 290 to 390 K, then T max is 390 K. For gas dividers where “max” is expressed as, x max / x span ; x max is the maximum gas concentration used during the verification, x span is the undivided, undiluted, span gas concentration, and the resulting ratio is the maximum divider point reference value used during the verification (typically 1). The following are special cases where “max” refers to a different value:
(i) For linearity verification of a PM balance, m max is the typical mass of a PM filter.
(ii) For linearity verification of a torque measurement system used with the engine's primary output shaft, T max is the manufacturer's specified peak torque of the lowest torque engine expected during testing.
(iii) For linearity verification of a fuel mass scale, m max is determined based on the range of engines and test interval durations expected during testing. It is the minimum, over all engines expected during testing, of the fuel consumption expected over the minimum test interval duration at the engine's maximum fuel rate. If the minimum test interval duration used during testing does not change with engine power or if the minimum test interval duration used during testing increases with engine power, m max is given by Eq. 1065.307-1. Calculate m max using the following equation:
(iv) For linearity verification of a DEF mass scale, m max is 10% of the value determined for a fuel mass scale in paragraph (e)(3)(iii) of this section. You may determine m max for a DEF mass scale by evaluating m max for a fuel mass scale based only on the DEF-using engines expected during testing.
(v) For linearity verification of a fuel flow rate meter, m max is the manufacturer's specified maximum fuel rate of the lowest-power engine expected during testing.
(vi) For linearity verification of a DEF flow rate meter, m max is 10% of the manufacturer's specified maximum fuel rate of the lowest-power DEF-using engine expected during testing.
(vii) For linearity verification of an intake-air flow rate meter, n max is the manufacturer's specified maximum intake-air flow rate (converted to molar flow rate) of the lowest-power engine expected during testing.
(viii) For linearity verification of a raw exhaust flow rate meter, n max is the manufacturer's specified maximum exhaust flow rate (converted to molar flow rate) of the lowest-power engine expected during testing.
(ix) For linearity verification of an electrical-power measurement system used to determine the engine's primary output shaft torque, P max is the manufacturer's specified maximum power of the lowest-power engine expected during testing.
(x) For linearity verification of an electrical-current measurement system used to determine the engine's primary output shaft torque, I max is the maximum current expected on the lowest-power engine expected during testing.
(xi) For linearity verification of an electrical-voltage measurement system used to determine the engine's primary output shaft torque, V max is the minimum peak voltage expected on the range of engines expected during testing.
(4) The specified ranges are inclusive. For example, a specified range of 0.98-1.02 for a 1 means 0.98≤ a 1 ≤1.02.
(5) Table 2 of this section describes optional verification procedures you may perform instead of linearity verification for certain systems. The following provisions apply for the alternative verification procedures:
(i) Perform the propane check verification described in § 1065.341 at the frequency specified in Table 1 of § 1065.303.
(ii) Perform the carbon balance error verification described in § 1065.543 on all test sequences that use the corresponding system. It must also meet the restrictions listed in Table 2 of this section. You may evaluate the carbon balance error verification multiple ways with different inputs to validate multiple flow-measurement systems.
(6) You must meet the a 1 criteria for these quantities only if the absolute value of the quantity is required, as opposed to a signal that is only linearly proportional to the actual value.
(7) Linearity verification is required for the following temperature measurements:
(i) The following temperature measurements always require linearity verification:
(A) Air intake.
(B) Aftertreatment bed(s), for engines tested with aftertreatment devices subject to cold-start testing.
(C) Dilution air for gaseous and PM sampling, including CVS, double-dilution, and partial-flow systems.
(D) PM sample.
(E) Chiller sample, for gaseous sampling systems that use thermal chillers to dry samples and use chiller temperature to calculate the dewpoint at the outlet of the chiller. For your testing, if you choose to use a high alarm temperature setpoint for the chiller temperature as a constant value in determining the amount of water removed from the emission sample, you may use good engineering judgment to verify the accuracy of the high alarm temperature setpoint instead of linearity verification on the chiller temperature. To verify that the alarm trip point value is no less than 2.0 °C below the reference value at the trip point, we recommend that you input a reference simulated temperature signal below the alarm trip point and increase this signal until the high alarm trips.
(F) Transmission oil.
(G) Axle gear oil.
(ii) Linearity verification is required for the following temperature measurements if these temperature measurements are specified by the engine manufacturer:
(A) Fuel inlet.
(B) Air outlet to the test cell's charge air cooler air outlet, for engines tested with a laboratory heat exchanger that simulates an installed charge air cooler.
(C) Coolant inlet to the test cell's charge air cooler, for engines tested with a laboratory heat exchanger that simulates an installed charge air cooler.
(D) Oil in the sump/pan.
(E) Coolant before the thermostat, for liquid-cooled engines.
(8) Linearity verification is required for the following pressure measurements:
(i) The following pressure measurements always require linearity verification:
(A) Air intake restriction.
(B) Exhaust back pressure as required in § 1065.130(h).
(C) Barometer.
(D) CVS inlet gage pressure where the raw exhaust enters the tunnel.
(E) Sample dryer, for gaseous sampling systems that use either osmotic-membrane or thermal chillers to dry samples. For your testing, if you choose to use a low alarm pressure setpoint for the sample dryer pressure as a constant value in determining the amount of water removed from the emission sample, you may use good engineering judgment to verify the accuracy of the low alarm pressure setpoint instead of linearity verification on the sample dryer pressure. To verify that the trip point value is no more than 4.0 kPa above the reference value at the trip point, we recommend that you input a reference pressure signal above the alarm trip point and decrease this signal until the low alarm trips.
(ii) Linearity verification is required for the following pressure measurements if these pressure measurements are specified by the engine manufacturer:
(A) The test cell's charge air cooler and interconnecting pipe pressure drop, for turbo-charged engines tested with a laboratory heat exchanger that simulates an installed charge air cooler.
(B) Fuel outlet.
(f) Performance criteria for measurement systems. Table 1 follows:
Table 1 of § 1065.307—Measurement Systems That Require Linearity Verification
a For flow meters that determine volumetric flow rate, V std , you may substitute V std for n as the quantity and substitute V stdmax for n max .
(g) Alternative verification procedures. Table 2 follows:
Table 2 of § 1065.307—Optional Verification to Linearity Verification
§ 1065.308   Continuous gas analyzer system-response and updating-recording verification—for gas analyzers not 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 gas species mole fraction (i.e., concentration) using a single gas detector, i.e., gas analyzers not continuously compensated for other gas species measured with multiple gas detectors. See § 1065.309 for verification procedures that apply to continuous gas analyzers that are continuously compensated for other gas species measured with multiple gas detectors. 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 analyzer systems or for continuous gas analyzer systems that are used only for discrete-mode testing. Perform this verification after initial installation (i.e., test cell commissioning) and after any modifications to the system that would change system response. For example, perform this verification if you add a significant volume to the transfer lines by increasing their length or adding a filter; or if you reduce the frequency at which the gas analyzer updates its output or the frequency at which you sample and record gas-analyzer concentrations.
(b) Measurement principles. This test verifies that the updating and recording frequencies match the overall system response to a rapid change in the value of concentrations at the sample probe. Gas analyzers and their sampling systems must be optimized such that their overall response to a rapid change in concentration is updated and recorded at an appropriate frequency to prevent loss of information. This test also verifies that the measurement system meets a minimum response time. You may use the results of this test to determine transformation time, t 50 , for the purposes of time alignment of continuous data in accordance with § 1065.650(c)(2)(i). You may also use an alternate procedure to determine t 50 in accordance with good engineering judgment. Note that any such procedure for determining t 50 must account for both transport delay and analyzer response time.
(c) System requirements. Demonstrate that each continuous analyzer has adequate update and recording frequencies and has a minimum rise time and a minimum fall time during a rapid change in gas concentration. You must meet one of the following criteria:
(1) The product of the mean rise time, t 10-90 , and the frequency at which the system records an updated concentration must be at least 5, and the product of the mean fall time, t 90-10 , and the frequency at which the system records an updated concentration must be at least 5. If the recording frequency is different than the analyzer's output update frequency, you must use the lower of these two frequencies for this verification, which is referred to as the updating-recording frequency. This verification applies to the nominal updating and recording frequencies. This criterion makes no assumption regarding the frequency content of changes in emission concentrations during emission testing; therefore, it is valid for any testing. Also, the mean rise time must be at or below 10 seconds and the mean fall time must be at or below 10 seconds.
(2) The frequency at which the system records an updated concentration must be at least 5 Hz. This criterion assumes that the frequency content of significant changes in emission concentrations during emission testing do not exceed 1 Hz. Also, the mean rise time must be at or below 10 seconds and the mean fall time must be at or below 10 seconds.
(3) You may use other criteria if we approve the criteria in advance.
(4) You may meet the overall PEMS verification in § 1065.920 instead of the verification in this section for field testing with PEMS.
(d) Procedure. Use the following procedure to verify the response of each continuous gas analyzer:
(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, t 50 , 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 N 2 with span gases diluted in air. You may use a multi-gas span gas, such as NO-CO-CO 2 -C 3 H 8 -CH 4 , 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 t 50 for time alignment, record this time as t 0 .
(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 t 50 for time alignment, record this time as t 100 .
(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.
(e) Performance evaluation. (1) If you choose to demonstrate compliance with paragraph (c)(1) of this section, use the data from paragraph (d)(3) of this section to calculate the mean rise time, t 10-90 , and mean fall time, t 90-10 , for each of the analyzers being verified. You may use interpolation between recorded values to determine rise and fall times. If the recording frequency used during emission testing is different from the analyzer's output update frequency, you must use the lower of these two frequencies for this verification. Multiply these times (in seconds) by their respective updating-recording frequencies in Hertz (1/second). The resulting product must be at least 5 for both rise time and fall time. If either value is less than 5, increase the updating-recording frequency, or adjust the flows or design of the sampling system to increase the rise time and fall time as needed. You may also configure analog or digital filters before recording to increase rise and fall times. In no case may the mean rise time or mean fall time be greater than 10 seconds.
(2) If a measurement system fails the criterion in paragraph (e)(1) of this section, ensure that signals from the system are updated and recorded at a frequency of at least 5 Hz. In no case may the mean rise time or mean fall time be greater than 10 seconds.
(3) If a measurement system fails the criteria in paragraphs (e)(1) and (2) of this section, you may use the measurement system only if the deficiency does not adversely affect your ability to show compliance with the applicable standards in this chapter.
(f) Transformation time, t 50 , determination. If you choose to determine t 50 for purposes of time alignment using data generated in paragraph (d)(3) of this section, calculate the mean t 0-50 and the mean t 100-50 from the recorded data. Average these two values to determine the final t 50 for the purposes of time alignment in accordance with § 1065.650(c)(2)(i).
(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 (e.g., 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 (e.g., 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 being drawn into the probe inlet. This avoids errors associated with overflowing span gas out of the probe inlet and drawing it back in when sampling ambient air.
(3) When sampling ambient air or ambient air mixed with 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 N 2 as the zero gas and ambient air (plus purified N 2 if needed) as the reference gas. Perform the verification with seven repeat measurements that each consist of stabilizing with purified N 2 , switching to ambient air and observing the analyzer's rise and stabilized reading, followed by switching back to purified N 2 and observing the analyzer's fall and stabilized reading.
§ 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 t 50 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 1066.620 for vehicle testing) and it does not apply to NMHC determination from THC and CH 4 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.
(b) Measurement principles. This procedure verifies that the updating and recording frequencies match the overall system response to a rapid change in the value of concentrations at the sample probe. It indirectly verifies the time-alignment and uniform response of all the continuous gas detectors used to generate a continuously combined/compensated concentration measurement signal. Gas analyzer systems must be optimized such that their overall response to rapid change in concentration is updated and recorded at an appropriate frequency to prevent loss of information. This test also verifies that the measurement system meets a minimum response time. For this procedure, ensure that all compensation algorithms and humidity corrections are turned on. You may use the results of this test to determine transformation time, t 50 , for the purposes of time alignment of continuous data in accordance with § 1065.650(c)(2)(i). You may also use an alternate procedure to determine t 50 consistent with good engineering judgment. Note that any such procedure for determining t 50 must account for both transport delay and analyzer response time.
(c) System requirements. Demonstrate that each continuously combined/compensated concentration measurement has adequate updating and recording frequencies and has a minimum rise time and a minimum fall time during a system response to a rapid change in multiple gas concentrations, including H 2 O concentration if H 2 O compensation is applied. You must meet one of the following criteria:
(1) The product of the mean rise time, t 10-90 , and the frequency at which the system records an updated concentration must be at least 5, and the product of the mean fall time, t 90-10 , and the frequency at which the system records an updated concentration must be at least 5. If the recording frequency is different than the update frequency of the continuously combined/compensated signal, you must use the lower of these two frequencies for this verification. This criterion makes no assumption regarding the frequency content of changes in emission concentrations during emission testing; therefore, it is valid for any testing. Also, the mean rise time must be at or below 10 seconds and the mean fall time must be at or below 10 seconds.
(2) The frequency at which the system records an updated concentration must be at least 5 Hz. This criterion assumes that the frequency content of significant changes in emission concentrations during emission testing do not exceed 1 Hz. Also, the mean rise time must be at or below 10 seconds and the mean fall time must be at or below 10 seconds.
(3) You may use other criteria if we approve them in advance.
(4) You may meet the overall PEMS verification in § 1065.920 instead of the verification in this section for field testing with PEMS.
(d) Procedure. Use the following procedure to verify the response of each continuously compensated analyzer (verify the combined signal, not each individual continuously combined concentration signal):
(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, t 50 , 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 H 2 O. 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 N 2 with span gases diluted in air. You may use a multi-gas span gas, such as NO-CO-CO 2 -C 3 H 8 -CH 4 , 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 H 2 O correction is applicable, then span gases must be humidified before entering the analyzer; however, you may not humidify NO 2 span gas by passing it through a sealed humidification vessel that contains H 2 O. You must humidify NO 2 span gas with another moist gas stream. We recommend humidifying your NO-CO-CO 2 -C 3 H 8 -CH 4 , balance N 2 , blended gas by bubbling the gas mixture that meets the specifications in § 1065.750 through distilled H 2 O in a sealed vessel and then mixing the gas with dry NO 2 gas, balance purified air, or by using a device that introduces distilled H 2 O as vapor into a controlled span gas flow. If the sample does not pass through a dryer during emission testing, humidify your span gas to an H 2 O level at or above the maximum expected during emission testing. If the sample passes through a dryer during emission testing, it must pass the sample dryer verification check in § 1065.342, and you must humidify your span gas to an H 2 O level at or above the level determined in § 1065.145(e)(2) for that dryer. If you are humidifying span gases without NO 2 , 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 H 2 O content. If you are humidifying span gases with NO 2 , 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 NO 2 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 °C 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.
(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 t 50 for time alignment, record this time as t 0 .
(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 t 50 for time alignment, record this time as t 100 .
(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.
(e) Performance evaluations. (1) If you choose to demonstrate compliance with paragraph (c)(1) of this section, use the data from paragraph (d)(3) of this section to calculate the mean rise time, t 10-90 , and mean fall time, t 90-10 , for the continuously combined signal from each analyzer being verified. You may use interpolation between recorded values to determine rise and fall times. If the recording frequency used during emission testing is different from the analyzer's output update frequency, you must use the lower of these two frequencies for this verification. Multiply these times (in seconds) by their respective updating-recording frequencies in Hz (1/second). The resulting product must be at least 5 for both rise time and fall time. If either value is less than 5, increase the updating-recording frequency or adjust the flows or design of the sampling system to increase the rise time and fall time as needed. You may also configure analog or digital filters before recording to increase rise and fall times. In no case may the mean rise time or mean fall time be greater than 10 seconds.
(2) If a measurement system fails the criterion in paragraph (e)(1) of this section, ensure that signals from the system are updated and recorded at a frequency of at least 5 Hz. In no case may the mean rise time or mean fall time be greater than 10 seconds.
(3) If a measurement system fails the criteria in paragraphs (e)(1) and (2) of this section, you may use the measurement system only if the deficiency does not adversely affect your ability to show compliance with the applicable standards in this chapter.
(f) Transformation time, t 50 , determination. If you choose to determine t 50 for purposes of time alignment using data generated in paragraph (d)(3) of this section, calculate the mean t 0-50 and the mean t 100-50 from the recorded data. Average these two values to determine the final t 50 for the purposes of time alignment in accordance with § 1065.650(c)(2)(i).
(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 H 2 O 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 H 2 O, 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 H 2 O 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.
§ 1065.310   Torque calibration.
(a) Scope and frequency. Calibrate all torque-measurement systems including dynamometer torque measurement transducers and systems upon initial installation and after major maintenance. Use good engineering judgment to repeat the calibration. Follow the torque transducer manufacturer's instructions for linearizing your torque sensor's output. We recommend that you calibrate the torque-measurement system with a reference force and a lever arm.
(b) Recommended procedure to quantify lever-arm length. Quantify the lever-arm length, NIST-traceable within ±0.5% uncertainty. The lever arm's length must be measured from the centerline of the dynamometer to the point at which the reference force is measured. The lever arm must be perpendicular to gravity (i.e., horizontal), and it must be perpendicular to the dynamometer's rotational axis. Balance the lever arm's torque or quantify its net hanging torque, NIST-traceable within ±1% uncertainty, and account for it as part of the reference torque.
(c) Recommended procedure to quantify reference force. We recommend dead-weight calibration, but you may use either of the following procedures to quantify the reference force, NIST-traceable within ±0.5% uncertainty.
(1) Dead-weight calibration. This technique applies a known force by hanging known weights at a known distance along a lever arm. Make sure the weights' lever arm is perpendicular to gravity (i.e., horizontal) and perpendicular to the dynamometer's rotational axis. Apply at least six calibration-weight combinations for each applicable torque-measuring range, spacing the weight quantities about equally over the range. Oscillate or rotate the dynamometer during calibration to reduce frictional static hysteresis. Determine each weight's reference force by multiplying its NIST-traceable mass by the local acceleration of Earth's gravity, as described in § 1065.630. Calculate the reference torque as the weights' reference force multiplied by the lever arm reference length.
(2) 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.
§ 1065.315   Pressure, temperature, and dewpoint calibration.
(a) Calibrate instruments for measuring pressure, temperature, and dewpoint upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration, as follows:
(1) Pressure. We recommend temperature-compensated, digital-pneumatic, or deadweight pressure calibrators, with data-logging capabilities to minimize transcription errors. We recommend using calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
(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 for absolute temperature 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 T max. If you use this option, you must use sensors that the supplier states are accurate to better than 0.5% of T max compared with their standard calibration curve.
(3) Dewpoint. We recommend a minimum of three different temperature-equilibrated and temperature-monitored calibration salt solutions in containers that seal completely around the dewpoint sensor. We recommend using calibration reference quantities for absolute dewpoint temperature that are NIST-traceable within ±0.5% uncertainty.
(b) You may remove system components for off-site calibration. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
§ 1065.320   Fuel-flow calibration.
(a) Calibrate fuel-flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration.
(b) [Reserved]
(c) You may remove system components for off-site calibration. When installing a flow meter with an off-site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
§ 1065.325   Intake-flow calibration.
(a) Calibrate intake-air flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration. We recommend using a calibration subsonic venturi, ultrasonic flow meter or laminar flow element. We recommend using calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
(b) You may remove system components for off-site calibration. When installing a flow meter with an off-site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
(c) If you use a subsonic venturi or ultrasonic flow meter for intake flow measurement, we recommend that you calibrate it as described in § 1065.340.
§ 1065.330   Exhaust-flow calibration.
(a) Calibrate exhaust-flow meters upon initial installation. Follow the instrument manufacturer's instructions and use good engineering judgment to repeat the calibration. We recommend that you use a calibration subsonic venturi or ultrasonic flow meter and simulate exhaust temperatures by incorporating a heat exchanger between the calibration meter and the exhaust-flow meter. If you can demonstrate that the flow meter to be calibrated is insensitive to exhaust temperatures, you may use other reference meters such as laminar flow elements, which are not commonly designed to withstand typical raw exhaust temperatures. We recommend using calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
(b) You may remove system components for off-site calibration. When installing a flow meter with an off-site calibration, we recommend that you consider the effects of the tubing configuration upstream and downstream of the flow meter. We recommend specifying calibration reference quantities that are NIST-traceable within ±0.5% uncertainty.
(c) If you use a subsonic venturi or ultrasonic flow meter for raw exhaust flow measurement, we recommend that you calibrate it as described in § 1065.340.
§ 1065.340   Diluted exhaust flow (CVS) calibration.
(a) Overview. This section describes how to calibrate flow meters for diluted exhaust constant-volume sampling (CVS) systems.
(b) Scope and frequency. Perform this calibration while the flow meter is installed in its permanent position, except as allowed in paragraph (c) of this section. Perform this calibration after you change any part of the flow configuration upstream or downstream of the flow meter that may affect the flow-meter calibration. Perform this calibration upon initial CVS installation and whenever corrective action does not resolve a failure to meet the diluted exhaust flow verification ( i.e. , propane check) in § 1065.341.
(c) Ex-situ CFV and SSV calibration. You may remove a CFV or SSV from its permanent position for calibration as long as it meets the following requirements when installed in the CVS:
(1) Upon installation of the CFV or SSV into the CVS, use good engineering judgment to verify that you have not introduced any leaks between the CVS inlet and the venturi.
(2) After ex-situ venturi calibration, you must verify all venturi flow combinations for CFVs or at minimum of 10 flow points for an SSV using the propane check as described in § 1065.341. Your propane check result for each venturi flow point may not exceed the tolerance in § 1065.341(f)(5).
(3) To verify your ex-situ calibration for a CVS with more than a single CFV, perform the following check to verify that there are no flow meter entrance effects that can prevent you from passing this verification.
(i) Use a constant flow device like a CFO kit to deliver a constant flow of propane to the dilution tunnel.
(ii) Measure hydrocarbon concentrations at a minimum of 10 separate flow rates for an SSV flow meter, or at all possible flow combinations for a CFV flow meter, while keeping the flow of propane constant. We recommend selecting CVS flow rates in a random order.
(iii) Measure the concentration of hydrocarbon background in the dilution air at the beginning and end of this test. Subtract the average background concentration from each measurement at each flow point before performing the regression analysis in paragraph (c)(3)(iv) of this section.
(iv) Perform a power regression using all the paired values of flow rate and corrected concentration to obtain a relationship in the form of y = a · x b . Use concentration as the independent variable and flow rate as the dependent variable. For each data point, calculate the difference between the measured flow rate and the value represented by the curve fit. The difference at each point must be less than ±1% of the appropriate regression value. The value of b must be between −1.005 and −0.995. If your results do not meet these limits, take corrective action consistent with § 1065.341(a).
(d) Reference flow meter. Calibrate a CVS flow meter using a reference flow meter such as a subsonic venturi flow meter, a long-radius ASME/NIST flow nozzle, a smooth approach orifice, a laminar flow element, a set of critical flow venturis, or an ultrasonic flow meter. Use a reference flow meter that reports quantities that are NIST-traceable within ±1% uncertainty. Use this reference flow meter's response to flow as the reference value for CVS flow-meter calibration.
(e) Configuration. Calibrate the system with any upstream screens or other restrictions that will be used during testing and that could affect the flow ahead of the CVS flow meter, using good engineering judgment to minimize the effect on the flow distribution. You may not use any upstream screen or other restriction that could affect the flow ahead of the reference flow meter, unless the flow meter has been calibrated with such a restriction. In the case of a free standing SSV reference flow meter, you may not have any upstream screens.
(f) PDP calibration. Calibrate a positive-displacement pump (PDP) to determine a flow-versus-PDP speed equation that accounts for flow leakage across sealing surfaces in the PDP as a function of PDP inlet pressure. Determine unique equation coefficients for each speed at which you operate the PDP. Calibrate a PDP flow meter as follows:
(1) Connect the system as shown in Figure 1 of this section.
(2) Leaks between the calibration flow meter and the PDP must be less than 0.3% of the total flow at the lowest calibrated flow point; for example, at the highest restriction and lowest PDP-speed point.
(3) While the PDP operates, maintain a constant temperature at the PDP inlet within ±2% of the mean absolute inlet temperature, T in .
(4) Set the PDP speed to the first speed point at which you intend to calibrate.
(5) Set the variable restrictor to its wide-open position.
(6) Operate the PDP for at least 3 min to stabilize the system. Continue operating the PDP and record the mean values of at least 30 seconds of sampled data of each of the following quantities:
(i) The mean flow rate of the reference flow meter, n ref . This may include several measurements of different quantities, such as reference meter pressures and temperatures, for calculating n ref .
(ii) The mean temperature at the PDP inlet, T in .
(iii) The mean static absolute pressure at the PDP inlet, p in .
(iv) The mean static absolute pressure at the PDP outlet, p out .
(v) The mean PDP speed, f nPDP .
(7) Incrementally close the restrictor valve to decrease the absolute pressure at the inlet to the PDP, p in .
(8) Repeat the steps in paragraphs (e)(6) and (7) of this section to record data at a minimum of six restrictor positions ranging from the wide open restrictor position to the minimum expected pressure at the PDP inlet or the maximum expected differential (outlet minus inlet) pressure across the PDP during testing.
(9) Calibrate the PDP by using the collected data and the equations in § 1065.640.
(10) Repeat the steps in paragraphs (e)(6) through (9) of this section for each speed at which you operate the PDP.
(11) Use the equations in § 1065.642 to determine the PDP flow equation for emission testing.
(12) Verify the calibration by performing a CVS verification ( i.e. , propane check) as described in § 1065.341.
(13) During emission testing ensure that the PDP is not operated either below the lowest inlet pressure point or above the highest differential pressure point in the calibration data.
(g) SSV calibration. Calibrate a subsonic venturi (SSV) to determine its calibration coefficient, C d, for the expected range of inlet pressures. Calibrate an SSV flow meter as follows:
(1) Connect the system as shown in Figure 1 of this section.
(2) Verify that any leaks between the calibration flow meter and the SSV are less than 0.3% of the total flow at the highest restriction.
(3) Start the blower downstream of the SSV.
(4) While the SSV operates, maintain a constant temperature at the SSV inlet within ±2% of the mean absolute inlet temperature, T in .
(5) Set the variable restrictor or variable-speed blower to a flow rate greater than the greatest flow rate expected during testing. You may not extrapolate flow rates beyond calibrated values, so we recommend that you make sure the Reynolds number, Re # , at the SSV throat at the greatest calibrated flow rate is greater than the maximum Re # expected during testing.
(6) Operate the SSV for at least 3 min to stabilize the system. Continue operating the SSV and record the mean of at least 30 seconds of sampled data of each of the following quantities:
(i) The mean flow rate of the reference flow meter n ref . This may include several measurements of different quantities for calculating n ref , such as reference meter pressures and temperatures.
(ii) Optionally, the mean dewpoint of the calibration air, T dew . See § 1065.640 for permissible assumptions.
(iii) The mean temperature at the venturi inlet, T in .
(iv) The mean static absolute pressure at the venturi inlet, P in .
(v) The mean static differential pressure between the static pressure at the venturi inlet and the static pressure at the venturi throat, Δ P SSV .
(7) Incrementally close the restrictor valve or decrease the blower speed to decrease the flow rate.
(8) Repeat the steps in paragraphs (g)(6) and (7) of this section to record data at a minimum of ten flow rates.
(9) Determine an equation to quantify C d as a function of Re # by using the collected data and the equations in § 1065.640. Section 1065.640 also includes statistical criteria for validating the C d versus Re # equation.
(10) Verify the calibration by performing a CVS verification ( i.e., propane check) as described in § 1065.341 using the new C d versus Re # equation.
(11) Use the SSV only between the minimum and maximum calibrated Re # . If you want to use the SSV at a lower or higher Re # , you must recalibrate the SSV.
(12) Use the equations in § 1065.642 to determine SSV flow during a test.
(h) CFV calibration. Calibrate a critical-flow venturi (CFV) to verify its discharge coefficient, C d, up to the highest expected pressure ratio, r, according to § 1065.640. Calibrate a CFV flow meter as follows:
(1) Connect the system as shown in Figure 1 of this section.
(2) Verify that any leaks between the calibration flow meter and the CFV are less than 0.3% of the total flow at the highest restriction.
(3) Start the blower downstream of the CFV.
(4) While the CFV operates, maintain a constant temperature at the CFV inlet within ±2% of the mean absolute inlet temperature, T in .
(5) Set the variable restrictor to its wide-open position. Instead of a variable restrictor, you may alternately vary the pressure downstream of the CFV by varying blower speed or by introducing a controlled leak. Note that some blowers have limitations on nonloaded conditions.
(6) Operate the CFV for at least 3 min to stabilize the system. Continue operating the CFV and record the mean values of at least 30 seconds of sampled data of each of the following quantities:
(i) The mean flow rate of the reference flow meter, n ref . This may include several measurements of different quantities, such as reference meter pressures and temperatures, for calculating n ref .
(ii) The mean dewpoint of the calibration air, T dew . See § 1065.640 for permissible assumptions during emission measurements.
(iii) The mean temperature at the venturi inlet, T in .
(iv) The mean static absolute pressure at the venturi inlet, P in .
(v) The mean static differential pressure between the CFV inlet and the CFV outlet, Δ P CFV .
(7) Incrementally close the restrictor valve or decrease the downstream pressure to decrease the differential pressure across the CFV, Δp CFV .
(8) Repeat the steps in paragraphs (f)(6) and (7) of this section to record mean data at a minimum of ten restrictor positions, such that you test the fullest practical range of Δ P CFV expected during testing. We do not require that you remove calibration components or CVS components to calibrate at the lowest possible restrictions.
(9) Determine C d and the highest allowable pressure ratio, r, according to § 1065.640.
(10) Use C d to determine CFV flow during an emission test. Do not use the CFV above the highest allowed r, as determined in § 1065.640.
(11) Verify the calibration by performing a CVS verification ( i.e., propane check) as described in § 1065.341.
(12) If your CVS is configured to operate more than one CFV at a time in parallel, calibrate your CVS by one of the following:
(i) Calibrate every combination of CFVs according to this section and § 1065.640. Refer to § 1065.642 for instructions on calculating flow rates for this option.
(ii) Calibrate each CFV according to this section and § 1065.640. Refer to § 1065.642 for instructions on calculating flow rates for this option.
(i) Ultrasonic flow meter calibration. [Reserved]
§ 1065.341   CVS and PFD flow verification (propane check).
This section describes two optional methods, using propane as a tracer gas, to verify CVS and PFD flow streams. You may use good engineering judgment and safe practices to use other tracer gases, such as CO 2 or CO. The first method, described in paragraphs (a) through (e) of this section, applies for the CVS diluted exhaust flow measurement system. The first method may also apply for other single-flow measurement systems as described in Table 2 of § 1065.307. Paragraph (g) of this section describes a second method you may use to verify flow measurements in a PFD for determining the PFD dilution ratio.
(a) A propane check uses either a reference mass or a reference flow rate of C 3 H 8 as a tracer gas in a CVS. Note that if you use a reference flow rate, account for any non-ideal gas behavior of C 3 H 8 in the reference flow meter. Refer to §§ 1065.640 and 1065.642, which describe how to calibrate and use certain flow meters. Do not use any ideal gas assumptions in §§ 1065.640 and 1065.642. The propane check compares the calculated mass of injected C 3 H 8 using HC measurements and CVS flow rate measurements with the reference value.
(b) Prepare for the propane check as follows:
(1) If you use a reference mass of C 3 H 8 instead of a reference flow rate, obtain a cylinder charged with C 3 H 8 . Determine the reference cylinder's mass of C 3 H 8 within ±0.5% of the amount of C 3 H 8 that you expect to use. You may substitute a C 3 H 8 analytical gas mixture (i.e., a prediluted tracer gas) for pure C 3 H 8 . This would be most appropriate for lower flow rates. The analytical gas mixture must meet the specifications in § 1065.750(a)(3).
(2) Select appropriate flow rates for the CVS and C 3 H 8 .
(3) Select a C 3 H 8 injection port in the CVS. Select the port location to be as close as practical to the location where you introduce engine exhaust into the CVS, or at some point in the laboratory exhaust tubing upstream of this location. Connect the C 3 H 8 cylinder to the injection system.
(4) Operate and stabilize the CVS.
(5) Preheat or pre-cool any heat exchangers in the sampling system.
(6) Allow heated and cooled components such as sample lines, filters, chillers, and pumps to stabilize at operating temperature.
(7) You may purge the HC sampling system during stabilization.
(8) If applicable, perform a vacuum side leak verification of the HC sampling system as described in § 1065.345.
(9) You may also conduct any other calibrations or verifications on equipment or analyzers.
(c) If you performed the vacuum-side leak verification of the HC sampling system as described in paragraph (b)(8) of this section, you may use the HC contamination procedure in § 1065.520(g) to verify HC contamination. Otherwise, zero, span, and verify contamination of the HC sampling system, as follows:
(1) Select the lowest HC analyzer range that can measure the C 3 H 8 concentration expected for the CVS and C 3 H 8 flow rates.
(2) Zero the HC analyzer using zero air introduced at the analyzer port.
(3) Span the HC analyzer using C 3 H 8 span gas introduced at the analyzer port.
(4) Overflow zero air at the HC probe inlet or into a tee near the outlet of the probe.
(5) Measure the stable HC concentration of the HC sampling system as overflow zero air flows. For batch HC measurement, fill the batch container (such as a bag) and measure the HC overflow concentration.
(6) If the overflow HC concentration exceeds 2 µmol/mol, do not proceed until contamination is eliminated. Determine the source of the contamination and take corrective action, such as cleaning the system or replacing contaminated portions.
(7) When the overflow HC concentration does not exceed 2 µmol/mol, record this value as x THCinit and use it to correct for HC contamination as described in § 1065.660.
(d) Perform the propane check as follows:
(1) For batch HC sampling, connect clean storage media, such as evacuated bags.
(2) Operate HC measurement instruments according to the instrument manufacturer's instructions.
(3) If you will correct for dilution air background concentrations of HC, measure and record background HC in the dilution air.
(4) Zero any integrating devices.
(5) Begin sampling, and start any flow integrators.
(6) Release the contents of the C 3 H 8 reference cylinder at the rate you selected. If you use a reference flow rate of C 3 H 8 , start integrating this flow rate.
(7) Continue to release the cylinder's contents until at least enough C 3 H 8 has been released to ensure accurate quantification of the reference C 3 H 8 and the measured C 3 H 8 .
(8) Shut off the C 3 H 8 reference cylinder and continue sampling until you have accounted for time delays due to sample transport and analyzer response.
(9) Stop sampling and stop any integrators.
(e) Perform post-test procedure as follows:
(1) If you used batch sampling, analyze batch samples as soon as practical.
(2) After analyzing HC, correct for contamination and background.
(3) Calculate total C 3 H 8 mass based on your CVS and HC data as described in § 1065.650 (40 CFR 1066.605 for vehicle testing) and § 1065.660, using the molar mass of C 3 H 8 , M C3H8 , instead of the effective molar mass of HC, M HC .
(4) If you use a reference mass, determine the cylinder's propane mass within ±0.5% and determine the C 3 H 8 reference mass by subtracting the empty cylinder propane mass from the full cylinder propane mass.
(5) Subtract the reference C 3 H 8 mass from the calculated mass. If this difference is within ±2% of the reference mass, the CVS passes this verification. If not, take corrective action as described in paragraph (f) of this section.
(f) A failed propane check might indicate one or more problems requiring corrective action, as follows:
Table 1 of § 1065.341—Troubleshooting Guide for Propane Checks
(g) You may verify flow measurements in a PFD (usually dilution air and diluted exhaust streams) for determining the dilution ratio in the PFD using the following method:
(1) Configure the HC sampling system to extract a sample from the PFD's diluted exhaust stream (such as near a PM filter). If the absolute pressure at this location is too low to extract an HC sample, you may sample HC from the PFD's pump exhaust. Use caution when sampling from pump exhaust because an otherwise acceptable pump leak downstream of a PFD diluted exhaust flow meter will cause a false failure of the propane check.
(2) Perform the propane check described in paragraphs (b), (c), and (d) of this section, but sample HC from the PFD's diluted exhaust stream. Inject the propane in the same exhaust stream that the PFD is sampling from (either CVS or raw exhaust stack).
(3) Calculate C 3 H 8 mass, taking into account the dilution from the PFD.
(4) Subtract the reference C 3 H 8 mass from the calculated mass. If this difference is within ±2% of the reference mass, all PFD flow measurements for determining PFD dilution ratio pass this verification. If not, take corrective action as described in paragraph (f) of this section. For PFDs sampling only for PM, the allowed difference is ±5%.
(h) Table 2 of § 1065.307 describes optional verification procedures you may perform instead of linearity verification for certain flow-measurement systems. Performing carbon balance error verification also replaces any required propane checks.
§ 1065.342   Sample dryer verification.
(a) Scope and frequency. If you use a sample dryer as allowed in § 1065.145(e)(2) to remove water from the sample gas, verify the performance upon installation, after major maintenance, for thermal chiller. For osmotic membrane dryers, verify the performance upon installation, after major maintenance, and within 35 days of testing.
(b) Measurement principles. Water can inhibit an analyzer's ability to properly measure the exhaust component of interest and thus is sometimes removed before the sample gas reaches the analyzer. For example water can negatively interfere with a CLD's NO X response through collisional quenching and can positively interfere with an NDIR analyzer by causing a response similar to CO.
(c) System requirements. The sample dryer must meet the specifications as determined in § 1065.145(e)(2) for dewpoint, T dew , and absolute pressure, p total , downstream of the osmotic-membrane dryer or thermal chiller.
(d) Sample dryer verification procedure. Use the following method to determine sample dryer performance. Run this verification with the dryer and associated sampling system operating in the same manner you will use for emission testing (including operation of sample pumps). You may run this verification test on multiple sample dryers sharing the same sampling system at the same time. You may run this verification on the sample dryer alone, but you must use the maximum gas flow rate expected during testing. You may use good engineering judgment to develop a different protocol.
(1) Use PTFE or stainless steel tubing to make necessary connections.
(2) Humidify room air, purified N 2 , or purified air by bubbling it through distilled H 2 O in a sealed vessel or use a device that injects distilled H 2 O as vapor into a controlled gas flow to humidify the gas to the highest sample H 2 O content that you estimate during emission sampling.
(3) Introduce the humidified gas upstream of the sample dryer. You may disconnect the transfer line from the probe and introduce the humidified gas at the inlet of the transfer line of the sample system used during testing. You may use the sample pumps in the sample system to draw gas through the vessel.
(4) Maintain the sample lines, fittings, and valves from the location where the humidified gas water content is measured to the inlet of the sampling system at a temperature at least 5 °C above the local humidified gas dewpoint. For dryers used in NO X sample systems, verify the sample system components used in this verification prevent aqueous condensation as required in § 1065.145(d)(1)(i). We recommend that the sample system components be maintained at least 5 °C above the local humidified gas dewpoint to prevent aqueous condensation.
(5) Measure the humidified gas dewpoint, T dew , and absolute pressure, p total , as close as possible to the inlet of the sample dryer or inlet of the sample system to verify the water content is at least as high as the highest value that you estimated during emission sampling. You may verify the water content based on any humidity parameter (e.g. mole fraction water, local dewpoint, or absolute humidity).
(6) Measure the humidified gas dewpoint, T dew , and absolute pressure, p total , as close as possible to the outlet of the sample dryer. Note that the dewpoint changes with absolute pressure. If the dewpoint at the sample dryer outlet is measured at a different pressure, then this reading must be corrected to the dewpoint at the sample dryer absolute pressure, p total .
(7) The sample dryer meets the verification if the dewpoint at the sample dryer pressure as measured in paragraph (d)(6) of this section is less than the dewpoint corresponding to the sample dryer specifications as determined in § 1065.145(e)(2) plus 2 °C or if the mole fraction of water as measured in (d)(6) is less than the corresponding sample dryer specifications plus 0.002 mol/mol.
(e) Alternate sample dryer verification procedure. The following method may be used in place of the sample dryer verification procedure in (d) of this section. If you use a humidity sensor for continuous monitoring of dewpoint at the sample dryer outlet you may skip the performance check in § 1065.342(d), but you must make sure that the dryer outlet humidity is at or below the minimum value used for quench, interference, and compensation checks.
§ 1065.345   Vacuum-side leak verification.
(a) Scope and frequency. Verify that there are no significant vacuum-side leaks using one of the leak tests described in this section. For laboratory testing, perform the vacuum-side leak verification upon initial sampling system installation, within 8 hours before the start of the first test interval of each duty-cycle sequence, and after maintenance such as pre-filter changes. For field testing, perform the vacuum-side leak verification after each installation of the sampling system on the vehicle, prior to the start of the field test, and after maintenance such as pre-filter changes. This verification does not apply to any full-flow portion of a CVS dilution system.
(b) Measurement principles. A leak may be detected either by measuring a small amount of flow when there should be zero flow, or by detecting the dilution of a known concentration of span gas when it flows through the vacuum side of a sampling system.
(c) Low-flow leak test. Test a sampling system for low-flow leaks as follows:
(1) Seal the probe end of the system by taking one of the following steps:
(i) Cap or plug the end of the sample probe.
(ii) Disconnect the transfer line at the probe and cap or plug the transfer line.
(iii) Close a leak-tight valve located in the sample transfer line within 92 cm of the probe.
(2) Operate all vacuum pumps. After stabilizing, verify that the flow through the vacuum-side of the sampling system is less than 0.5% of the system's normal in-use flow rate. You may estimate typical analyzer and bypass flows as an approximation of the system's normal in-use flow rate.
(d) Dilution-of-span-gas leak test. You may use any gas analyzer for this test. If you use a FID for this test, correct for any HC contamination in the sampling system according to § 1065.660. If you use an O 2 analyzer described in § 1065.280 for this test, you may use purified N 2 to detect a leak. To avoid misleading results from this test, we recommend using only analyzers that have a repeatability of 0.5% or better at the reference gas concentration used for this test. Perform a vacuum-side leak test as follows:
(1) Prepare a gas analyzer as you would for emission testing.
(2) Supply reference gas to the analyzer span port and record the measured value.
(3) Route overflow reference gas to the inlet of the sample probe or at a tee fitting in the transfer line near the exit of the probe. You may use a valve upstream of the overflow fitting to prevent overflow of reference gas out of the inlet of the probe, but you must then provide an overflow vent in the overflow supply line.
(4) Verify that the measured overflow reference gas concentration is within ±0.5% of the concentration measured in paragraph (d)(2) of this section. A measured value lower than expected indicates a leak, but a value higher than expected may indicate a problem with the reference gas or the analyzer itself. A measured value higher than expected does not indicate a leak.
(e) Vacuum-decay leak test. To perform this test you must apply a vacuum to the vacuum-side volume of your sampling system and then observe the leak rate of your system as a decay in the applied vacuum. To perform this test you must know the vacuum-side volume of your sampling system to within ±10% of its true volume. For this test you must also use measurement instruments that meet the specifications of subpart C of this part and of this subpart D. Perform a vacuum-decay leak test as follows:
(1) Seal the probe end of the system as close to the probe opening as possible by taking one of the following steps:
(i) Cap or plug the end of the sample probe.
(ii) Disconnect the transfer line at the probe and cap or plug the transfer line.
(iii) Close a leak-tight valve located in the sample transfer line within 92 cm of the probe.
(2) Operate all vacuum pumps. Draw a vacuum that is representative of normal operating conditions. In the case of sample bags, we recommend that you repeat your normal sample bag pump-down procedure twice to minimize any trapped volumes.
(3) Turn off the sample pumps and seal the system. Measure and record the absolute pressure of the trapped gas and optionally the system absolute temperature. Wait long enough for any transients to settle and long enough for a leak at 0.5% to have caused a pressure change of at least 10 times the resolution of the pressure transducer, then again record the pressure and optionally temperature.
(4) Calculate the leak flow rate based on an assumed value of zero for pumped-down bag volumes and based on known values for the sample system volume, the initial and final pressures, optional temperatures, and elapsed time. Using the calculations specified in § 1065.644, verify that the vacuum-decay leak flow rate is less than 0.5% of the system's normal in-use flow rate.
§ 1065.350   H2O interference verification for CO2NDIR analyzers.
(a) Scope and frequency. If you measure CO 2 using an NDIR analyzer, verify the amount of H 2 O interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. H 2 O can interfere with an NDIR analyzer's response to CO 2 . If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. A CO 2 NDIR analyzer must have an H 2 O interference that is within (0.0 ±0.4) mmol/mol, though we strongly recommend a lower interference that is within (0.0 ±0.2) mmol/mol.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the CO 2 NDIR analyzer as you would before an emission test. 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 H 2 O in a sealed vessel or use a device that introduces distilled H 2 O as vapor into a controlled gas flow. If the sample does not pass through a dryer during emission testing, humidify your test gas to an H 2 O level at or above the maximum expected during emission testing. If the sample passes through a dryer during emission testing, you must humidify your test gas to an H 2 O level at or above 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 H 2 O mole fraction, x H2O , of the humidified test gas, as close as possible to the inlet of the analyzer. For example, measure dewpoint, T dew , and absolute pressure, p total , to calculate x H2O . Verify that the H 2 O 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 H 2 O 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 H 2 O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature. Use good engineering judgment to estimate the H 2 O content. For example, you may use previous direct measurements of H 2 O 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 x H2O 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 x H2O is measured to the analyzer are at least 5 °C 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) Operate the analyzer to get a reading for CO 2 concentration and record results 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.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your CO 2 sampling system and your emission-calculation procedures, the H 2 O interference for your CO 2 NDIR analyzer always affects your brake-specific emission results within ±0.5% of each of the applicable standards in this chapter. 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 CO 2 NDIR analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.355   H2O and CO2interference verification for CO NDIR analyzers.
(a) Scope and frequency. If you measure CO using an NDIR analyzer, verify the amount of H 2 O and CO 2 interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. H 2 O and CO 2 can positively interfere with an NDIR analyzer by causing a response similar to CO. If the NDIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. A CO NDIR analyzer must have combined H 2 O and CO 2 interference that is within ±2 % of the flow-weighted mean concentration of CO expected at the standard, though we strongly recommend a lower interference that is within ±1%.
(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 CO 2 test gas by bubbling a CO 2 span gas that meets the specifications in § 1065.750 through distilled H 2 O in a sealed vessel or use a device that introduces distilled H 2 O as vapor into a controlled gas flow. If the sample does not pass through a dryer during emission testing, humidify your test gas to an H 2 O level at or above the maximum expected during emission testing. If the sample passes through a dryer during emission testing, you must humidify your test gas to an H 2 O at or above the level determined in § 1065.145(e)(2) for that dryer. Use a CO 2 span gas concentration at least as high as the maximum expected during testing.
(3) Introduce the humidified CO 2 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 H 2 O mole fraction, x H2O , of the humidified CO 2 test gas as close as possible to the inlet of the analyzer. For example, measure dewpoint, T dew , and absolute pressure, p total , to calculate x H 2 O . Verify that the H 2 O 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 H 2 O 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 H 2 O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature. Use good engineering judgment to estimate the H 2 O content. For example, you may use previous direct measurements of H 2 O 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 x H2O 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 x H2O is measured to the analyzer are at least 5 °C 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) Operate the analyzer to get a reading for CO concentration and record results 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 CO 2 and H 2 O separately. If the CO 2 and H 2 O 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 H 2 O (down to 0.025 mol/mol H 2 O content) that are lower than the maximum levels expected during testing, but you must scale up the observed H 2 O interference by multiplying the observed interference by the ratio of the maximum expected H 2 O 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.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your CO sampling system and your emission-calculation procedures, the combined CO 2 and H 2 O interference for your CO NDIR analyzer always affects your brake-specific CO emission results within ±0.5% of the applicable CO standard.
(2) You may use a CO NDIR analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.357   CO2interference verification for H2O FTIR analyzers.
(a) Scope and frequency. If you measure H 2 O using an FTIR analyzer, verify the amount of CO 2 interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. CO 2 can interfere with an FTIR analyzer's response to H 2 O. If the FTIR analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. An H 2 O FTIR analyzer must have a CO 2 interference that is within (0.0 ± 0.4) mmol/mol, though we strongly recommend a lower interference that is within (0.0 ± 0.2) mmol/mol.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the H 2 O FTIR analyzer as you would before an emission test.
(2) Use a CO 2 span gas that meets the specifications of § 1065.750 and a concentration that is approximately the maximum CO 2 concentration expected during emission testing.
(3) Introduce the CO 2 test gas into the sample system.
(4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.
(5) Operate the analyzer to get a reading for H 2 O concentration and record results for 30 seconds. Calculate the arithmetic mean of these data.
(6) The analyzer meets the interference verification if the result of paragraph (d)(5) of this section meets the tolerance in paragraph (c) of this section.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification for CO 2 for engines operating on fuels other than carbon-containing fuels.
(2) You may omit this verification if you can show by engineering analysis that for your H 2 O sampling system and your emission-calculation procedures, the CO 2 interference for your H 2 O FTIR analyzer always affects your brake-specific emission results within ±0.5% of each of the applicable standards in this chapter. This specification also applies for vehicle testing, except that it relates to emission results in g/mile or g/kilometer.
(3) You may use an H 2 O FTIR analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.360   FID optimization and verification.
(a) Scope and frequency. For all FID analyzers, calibrate the FID upon initial installation. Repeat the calibration as needed using good engineering judgment. For a FID that measures THC, perform the following steps:
(1) Optimize the response to various hydrocarbons after initial analyzer installation and after major maintenance as described in paragraph (c) of this section.
(2) Determine the methane (CH 4 ) response factor after initial analyzer installation and after major maintenance as described in paragraph (d) of this section.
(3) If you determine NMNEHC by subtracting from measured THC, determine the ethane (C 2 H 6 ) response factor after initial analyzer installation and after major maintenance as described in paragraph (f) of this section. Verify the C 2 H 6 response within 185 days before testing as described in paragraph (f) of this section.
(4) You may determine the methane (CH 4 ) and ethane (C 2 H 6 ) response factors as a function of the molar water concentration in the raw or diluted exhaust. If you choose the option in this paragraph (a)(4), generate and verify the humidity level (or fraction) as described in § 1065.365(g).
(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 C 3 H 8 calibration gases that meet the specifications of § 1065.750. For a FID that measures CH 4 , calibrate using CH 4 calibration gases that meet the specifications of § 1065.750. We recommend FID analyzer zero and span gases that contain approximately the flow-weighted mean concentration of O 2 expected during testing. If you use a FID to measure CH 4 downstream of a nonmethane cutter (NMC), you may calibrate that FID using CH 4 calibration gases with the NMC. Regardless of the calibration gas composition, calibrate on a carbon number basis of one (C 1 ). For example, if you use a C 3 H 8 span gas of concentration 200 µmol/mol, span the FID to respond with a value of 600 µmol/mol. As another example, if you use a CH 4 span gas with a concentration of 200 µmol/mol, span the FID to respond with a value of 200 µmol/mol.
(c) THC FID response optimization. This procedure is only for FID analyzers that measure THC. Use good engineering judgment for initial instrument start-up and basic operating adjustment using FID fuel and zero air. Heated FIDs must be within their required operating temperature ranges. Optimize FID response at the most common analyzer range expected during emission testing. Optimization involves adjusting flows and pressures of FID fuel, burner air, and sample to minimize response variations to various hydrocarbon species in the exhaust. Use good engineering judgment to trade off peak FID response to propane calibration gases to achieve minimal response variations to different hydrocarbon species. For an example of trading off response to propane for relative responses to other hydrocarbon species, see SAE 770141 (incorporated by reference, see § 1065.1010). Determine the optimum flow rates and/or pressures for FID fuel, burner air, and sample and record them for future reference.
(d) THC FID CH 4 response factor determination. This procedure is only for FID analyzers that measure THC. Since FID analyzers generally have a different response to CH 4 versus C 3 H 8 , determine the THC-FID analyzer's CH 4 response factor, RF CH4[THC-FID], after FID optimization. Use the most recent RF CH4[THC-FID] measured according to this section in the calculations for HC determination described in § 1065.660 to compensate for CH 4 response. Determine RF CH4[THC-FID] as follows, noting that you do not determine RF CH4[THC-FID] for FIDs that are calibrated and spanned using CH 4 with an NMC:
(1) Select a C 3 H 8 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 C 3 H 8 concentration of the gas.
(2) Select a CH 4 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 CH 4 concentration of the gas.
(3) Start and operate the FID analyzer according to the manufacturer's instructions.
(4) Confirm that the FID analyzer has been calibrated using C 3 H 8 . Calibrate on a carbon number basis of one (C 1 ). For example, if you use a C 3 H 8 span gas of concentration 200 µmol/mol, span the FID to respond with a value of 600 µmol/mol.
(5) Zero the FID with a zero gas that you use for emission testing.
(6) Span the FID with the C 3 H 8 span gas that you selected under paragraph (d)(1) of this section.
(7) Introduce the CH 4 span gas that you selected under paragraph (d)(2) of this section into the FID analyzer.
(8) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the analyzer and to account for its response.
(9) While the analyzer measures the CH 4 concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of these values.
(10) 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 CH 4 calibration gas. The result is the FID analyzer's response factor for CH 4 , RF CH4[THC-FID] .
(12) You may determine the response factor as a function of molar water concentration using the following procedures and use this response factor to account for the CH 4 response for NMHC determination described in § 1065.660(b)(2)(iii):
(i) Humidify the CH 4 span gas as described in § 1065.365(g) and repeat the steps in paragraphs (d)(7) through (9) of this section until measurements are complete for each setpoint in the selected range.
(ii) Divide each mean measured CH 4 concentration by the recorded span concentration of the CH 4 calibration gas, adjusted for water content, to determine the FID analyzer's CH 4 response factor, RF CH4[THC-FID].
(iii) Use the CH 4 response factors at the different setpoints to create a functional relationship between response factor and molar water concentration, downstream of the last sample dryer if any sample dryers are present.
(iv) Use this functional relationship to determine the response factor during an emission test.
(e) THC FID CH 4 response verification. This procedure is only for FID analyzers that measure THC. Verify RF CH4[THC-FID] as follows:
(1) Perform a CH 4 response factor determination as described in paragraph (d) of this section. If the resulting value of RF CH4[THC-FID] is within ±5% of its most recent previously determined value, the THC FID passes the CH 4 response verification. For example, if the most recent previous value for RF CH4[THC-FID] was 1.05 and it increased by 0.05 to become 1.10 or it decreased by 0.05 to become 1.00, either case would be acceptable because ±4.8% is less than ±5%.
(2) If RF CH4[THC-FID] is not within the tolerance specified in paragraph (e)(1) of this section, use good engineering judgment to verify that the flow rates and/or pressures of FID fuel, burner air, and sample are at their most recent previously recorded values, as determined in paragraph (c) of this section. You may adjust these flow rates as necessary. Then determine the RF CH4[THC-FID] as described in paragraph (d) of this section and verify that it is within the tolerance specified in this paragraph (e).
(3) If RF CH4[THC-FID] is not within the tolerance specified in this paragraph (e), re-optimize the FID response as described in paragraph (c) of this section.
(4) Determine a new RF CH4[THC-FID] as described in paragraph (d) of this section. Use this new value of RF CH4[THC-FID] in the calculations for HC determination, as described in § 1065.660.
(5) For analyzers with multiple ranges, you need to perform the procedure in this paragraph (e) only on a single range.
(f) THC FID C 2 H 6 response factor determination. This procedure is only for FID analyzers that measure THC. Since FID analyzers generally have a different response to C 2 H 6 than C 3 H 8 , determine the THC-FID analyzer's C 2 H 6 response factor, RF C2H6[THC-FID], after FID optimization using the procedure described in paragraph (d) of this section, replacing CH 4 with C 2 H 6 . Use the most recent RF C2H6[THC-FID] measured according to this section in the calculations for HC determination described in § 1065.660 to compensate for C 2 H 6 response.
§ 1065.362   Non-stoichiometric raw exhaust FID O2interference verification.
(a) Scope and frequency. If you use FID analyzers for raw exhaust measurements from engines that operate in a non-stoichiometric mode of combustion (e.g., compression-ignition, lean-burn), verify the amount of FID O 2 interference upon initial installation and after major maintenance.
(b) Measurement principles. Changes in O 2 concentration in raw exhaust can affect FID response by changing FID flame temperature. Optimize FID fuel, burner air, and sample flow to meet this verification. Verify FID performance with the compensation algorithms for FID O 2 interference that you have active during an emission test.
(c) System requirements. Any FID analyzer used during testing must meet the FID O 2 interference verification according to the procedure in this section.
(d) Procedure. Determine FID O 2 interference as follows, noting that you may use one or more gas dividers to create the reference gas concentrations that are required to perform this verification:
(1) Select three span reference gases that contain a C 3 H 8 concentration that you use to span your analyzers before emission testing. Use only span gases that meet the specifications of § 1065.750. You may use CH 4 span reference gases for FIDs calibrated on CH 4 with a nonmethane cutter. Select the three balance gas concentrations such that the concentrations of O 2 and N 2 represent the minimum, maximum, and average O 2 concentrations expected during testing. The requirement for using the average O 2 concentration can be removed if you choose to calibrate the FID with span gas balanced with the average expected oxygen concentration.
(2) Confirm that the FID analyzer meets all the specifications of § 1065.360.
(3) Start and operate the FID analyzer as you would before an emission test. Regardless of the FID burner's air source during testing, use zero air as the FID burner's air source for this verification.
(4) Zero the FID analyzer using the zero gas used during emission testing.
(5) Span the FID analyzer using a span gas that you use during emission testing.
(6) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of sampled data is within ±0.5% of the span reference value used in paragraph (d)(5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph (d)(4) of this section.
(7) Check the analyzer response using the span gas that has the minimum concentration of O 2 expected during testing. Record the mean response of 30 seconds of stabilized sample data as x O2minHC .
(8) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of stabilized sample data is within ±0.5% of the span reference value used in paragraph (d)(5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph (d)(4) of this section.
(9) Check the analyzer response using the span gas that has the average concentration of O 2 expected during testing. Record the mean response of 30 seconds of stabilized sample data as x O2avgHC .
(10) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of stabilized sample data is within ±0.5% of the span reference value used in paragraph (d)(5) of this section, proceed to the next step; otherwise restart the procedure at paragraph (d)(4) of this section.
(11) Check the analyzer response using the span gas that has the maximum concentration of O 2 expected during testing. Record the mean response of 30 seconds of stabilized sample data as x O2maxHC .
(12) Check the zero response of the FID analyzer using the zero gas used during emission testing. If the mean zero response of 30 seconds of stabilized sample data is within ±0.5% of the span reference value used in paragraph (d)(5) of this section, then proceed to the next step; otherwise restart the procedure at paragraph (d)(4) of this section.
(13) Calculate the percent difference between x O2maxHC and its reference gas concentration. Calculate the percent difference between x O2avgHC and its reference gas concentration. Calculate the percent difference between x O2minHC and its reference gas concentration. Determine the maximum percent difference of the three. This is the O 2 interference.
(14) If the O 2 interference is within ±2%, the FID passes the O 2 interference verification; otherwise perform one or more of the following to address the deficiency:
(i) Repeat the verification to determine if a mistake was made during the procedure.
(ii) Select zero and span gases for emission testing that contain higher or lower O 2 concentrations and repeat the verification.
(iii) Adjust FID burner air, fuel, and sample flow rates. Note that if you adjust these flow rates on a THC FID to meet the O 2 interference verification, you have reset RF CH4 for the next RF CH4 verification according to § 1065.360. Repeat the O 2 interference verification after adjustment and determine RF CH4 .
(iv) Repair or replace the FID and repeat the O 2 interference verification.
(v) Demonstrate that the deficiency does not adversely affect your ability to demonstrate compliance with the applicable emission standards.
(15) For analyzers with multiple ranges, you need to perform the procedure in this paragraph (d) only on a single range.
§ 1065.365   Nonmethane cutter penetration fractions and NMC FID response factors.
(a) Scope and frequency. If you use a FID analyzer and an NMC to measure methane (CH 4 ), verify that the catalytic activity of the NMC has not deteriorated as described in this section. Determine the NMC's penetration fractions (PF) of CH 4 and ethane (C 2 H 6 ) and, if applicable, the FID analyzer response factors using the appropriate procedures of paragraph (d), (e), or (f) of this section. 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 NMC and repeat this verification within 185 days of testing. Note that because NMCs 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 an NMC's penetration fractions more frequently. Use the most recently determined penetration fraction from this section to calculate HC emissions according to § 1065.660 as applicable.
(b) Measurement principles. An NMC is a heated catalyst that removes nonmethane hydrocarbons from an exhaust sample stream before the FID analyzer measures the remaining hydrocarbon concentration. An ideal NMC would have a CH 4 penetration fraction, PF CH4, of 1.000, and the penetration fraction for all other nonmethane hydrocarbons would be 0.000, as represented by PF C2H6. The emission calculations in § 1065.660 use the measured values from this verification to account for less than ideal NMC performance.
(c) System requirements. We do not require that you limit NMC penetration fractions to a certain range. However, we recommend that you optimize an NMC by adjusting its temperature to achieve a PF C2H6 <0.02, as determined by paragraph (d), (e), or (f) of this section, as applicable, using dry gases. If adjusting NMC temperature does not result in achieving the recommended PF C2H6 level, we recommend that you replace the catalyst material. Note that, if we use an NMC for testing, we will optimize it to achieve a PF C2H6 <0.02.
(d) Procedure for a FID calibrated with the NMC. The following procedure describes the recommended method for verifying NMC performance and the required method for any gaseous-fueled engine, including dual-fuel and flexible-fuel engines.
(1) Select CH 4 and C 2 H 6 analytical gas mixtures and ensure that both mixtures meet the specifications of § 1065.750. Select a CH 4 concentration that you would use for spanning the FID during emission testing and select a C 2 H 6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value. For CH 4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
(2) Start, operate, and optimize the NMC according to the manufacturer's instructions, including any temperature optimization.
(3) Confirm that the FID analyzer meets all the specifications of § 1065.360.
(4) Start and operate the FID analyzer according to the manufacturer's instructions.
(5) Zero and span the FID with the NMC as you would during emission testing. Span the FID through the NMC by using CH 4 span gas.
(6) Introduce the C 2 H 6 analytical gas mixture upstream of the NMC. Use good engineering judgment to address the effect of hydrocarbon contamination if your point of introduction is vastly different from the point of zero/span gas introduction.
(7) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the NMC and to account for the analyzer's response.
(8) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of the analytical gas mixture.
(9) Calculate a reference concentration of C 2 H 6 , by converting C 2 H 6 to a C 1 basis and adjusted for water content, if necessary. Calculate the combined C 2 H 6 response factor and penetration fraction, RFPF C2H6[NMC-FID], by dividing the mean C 2 H 6 concentration from paragraph (d)(8) of this section by the reference concentration of C 2 H 6 . For any gaseous-fueled engine, including dual-fuel and flexible-fuel engines, you must determine RFPF C2H6[NMC-FID] as a function of the molar water concentration in the raw or diluted exhaust using paragraph (g) of this section. Use RFPF C2H6[NMC-FID] at the different setpoints to create a functional relationship between RFPF C2H6[NMC-FID] and molar water concentration, downstream of the last sample dryer if any sample dryers are present. Use this functional relationship to determine the combined response factor and penetration fraction during the emission test. For any other engine you may use the same procedure or you may determine RFPF C2H6[NMC-FID] at zero molar water concentration.
(10) For any gaseous-fueled engine, including dual-fuel and flexible-fuel engines, repeat the steps in paragraphs (d)(6) through (9) of this section, but with the CH 4 analytical gas mixture instead of C 2 H 6 and determine RFPF CH4[NMC-FID] as a function of the molar water concentration in the raw or diluted exhaust using paragraph (g) of this section. Note that RFPF CH4[NMC-FID] is set equal to 1.0 only for zero molar water concentration. For any other engine you may use the same procedure, or you may set RFPF CH4[NMC-FID] equal to 1.0.
(11) Use RFPF C2H6[NMC-FID] and RFPF CH4[NMC-FID] in emission calculations according to § 1065.660(b)(2)(i) and (d)(1)(i).
(e) Procedure for a FID calibrated with propane, bypassing the NMC. If you use a single FID for THC and CH 4 determination with an NMC that is calibrated with propane, C 3 H 8 , by bypassing the NMC, determine its penetration fractions, PF C2H6[NMC-FID] and PF CH4[NMC-FID], as follows:
(1) Select CH 4 and C 2 H 6 analytical gas mixtures and ensure that both mixtures meet the specifications of § 1065.750. Select a CH 4 concentration that you would use for spanning the FID during emission testing and select a C 2 H 6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard and the C 2 H 6 concentration typical of the peak total hydrocarbon (THC) concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value. For CH 4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
(2) Start and operate the NMC according to the manufacturer's instructions, including any temperature optimization.
(3) Confirm that the FID analyzer meets all the specifications of § 1065.360.
(4) Start and operate the FID analyzer according to the manufacturer's instructions.
(5) Zero and span the FID as you would during emission testing. Span the FID by bypassing the NMC and by using C 3 H 8 span gas. Note that you must span the FID on a C 1 basis. For example, if your span gas has a propane reference value of 100 µmol/mol, the correct FID response to that span gas is 300 µmol/mol because there are three carbon atoms per C 3 H 8 molecule.
(6) Introduce the C 2 H 6 analytical gas mixture upstream of the NMC. Use good engineering judgment to address the effect of hydrocarbon contamination if your point of introduction is vastly different from the point of zero/span gas introduction.
(7) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the NMC and to account for the analyzer's response.
(8) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of the analytical gas mixture.
(9) Reroute the flow path to bypass the NMC, introduce the C 2 H 6 analytical gas mixture, and repeat the steps in paragraphs (e)(7) and (8) of this section.
(10) Divide the mean C 2 H 6 concentration measured through the NMC by the mean C 2 H 6 concentration measured after bypassing the NMC. The result is the C 2 H 6 penetration fraction, PF C2H6[NMC-FID]. Use this penetration fraction according to § 1065.660(b)(2)(ii) and (d)(1)(ii).
(11) Repeat the steps in paragraphs (e)(6) through (10) of this section, but with the CH 4 analytical gas mixture instead of C 2 H 6 . The result will be the CH 4 penetration fraction, PF CH4[NMC-FID]. Use this penetration fraction according to § 1065.660(b)(2)(ii) or § 1065.665, as applicable.
(f) Procedure for a FID calibrated with CH 4, bypassing the NMC . If you use a FID with an NMC that is calibrated with CH 4 by bypassing the NMC, determine its combined C 2 H 6 response factor and penetration fraction, RFPF C2H6[NMC-FID], as well as its CH 4 penetration fraction, PF CH4[NMC-FID ], as follows:
(1) Select CH 4 and C 2 H 6 analytical gas mixtures and ensure that both mixtures meet the specifications of § 1065.750. Select a CH 4 concentration that you would use for spanning the FID during emission testing and select a C 2 H 6 concentration that is typical of the peak NMHC concentration expected at the hydrocarbon standard or equal to the THC analyzer's span value. For CH 4 analyzers with multiple ranges, perform this procedure on the highest range used for emission testing.
(2) Start and operate the NMC according to the manufacturer's instructions, including any temperature optimization.
(3) Confirm that the FID analyzer meets all the specifications of § 1065.360.
(4) Start and operate the FID analyzer according to the manufacturer's instructions.
(5) Zero and span the FID as you would during emission testing. Span the FID by bypassing the NMC and by using CH 4 span gas.
(6) Introduce the C 2 H 6 analytical gas mixture upstream of the NMC. Use good engineering judgment to address the effect of hydrocarbon contamination if your point of introduction is vastly different from the point of zero/span gas introduction.
(7) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the NMC and to account for the analyzer's response.
(8) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of the analytical gas mixture.
(9) Divide the mean C 2 H 6 concentration by the reference concentration of C 2 H 6 , converted to a C 1 basis. The result is the combined C 2 H 6 response factor and C 2 H 6 penetration fraction, RFPF C2H6[NMC-FID]. Use this combined C 2 H 6 response factor and penetration fraction according to § 1065.660(b)(2)(iii) and (d)(1)(iii).
(10) Introduce the CH 4 analytical gas mixture upstream of the NMC. Use good engineering judgment to address the effect of hydrocarbon contamination if your point of introduction is vastly different from the point of zero/span gas introduction.
(11) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the NMC and to account for the analyzer's response.
(12) While the analyzer measures a stable concentration, record 30 seconds of sampled data. Calculate the arithmetic mean of these data points.
(13) Reroute the flow path to bypass the NMC, introduce the CH 4 analytical gas mixture, and repeat the steps in paragraphs (e)(11) and (12) of this section.
(14) Divide the mean CH 4 concentration measured through the NMC by the mean CH 4 concentration measured after bypassing the NMC. The result is the CH 4 penetration fraction, PF CH4[NMC-FID]. Use this CH 4 penetration fraction according to § 1065.660(b)(2)(iii) and (d)(1)(iii).
(g) Test gas humidification. If you are generating gas mixtures as a function of the molar water concentration in the raw or diluted exhaust according to paragraph (d) of this section, create a humidified test gas by bubbling the analytical gas mixture that meets the specifications in § 1065.750 through distilled H 2 O in a sealed vessel or use a device that introduces distilled H 2 O as vapor into a controlled gas flow. Determine the mole fraction of H 2 O in the humidified calibration gas, x H2Oref, as an average value over intervals of at least 30 seconds. We recommend that you design your system to maintain temperatures at least 5  °C above the local calibration gas dewpoint in any transfer lines, fittings, and valves between the point at which you determine x H2Oref and the analyzer. Verify the humidity generator's uncertainty upon initial installation, within 370 days before verifying response factors and penetration fractions, and after major maintenance. Use the uncertainties from the calibration of the humidity generator's measurements and follow NIST Technical Note 1297 (incorporated by reference, see § 1065.1010) to verify that the amount of H 2 O in x H2Oref is determined within ±3% uncertainty, U xH2O, for one of the options described in § 1065.750(a)(6). If the humidity generator requires assembly before use, after assembly follow the instrument manufacturer's instructions to check for leaks.
(1) If the sample does not pass through a dryer during emission testing, generate at least five different H 2 O concentrations that cover the range from less than the minimum expected to greater than the maximum expected water concentration during testing. Use good engineering judgment to determine the target concentrations.
(2) If the sample passes through a dryer during emission testing, humidify your test gas to an H 2 O level at or above the level determined in § 1065.145(e)(2) for that dryer and determine a single wet analyzer response to the dehumidified sample.
§ 1065.366   Interference verification for FTIR analyzers.
(a) Scope and frequency. If you measure CH 4 , C 2 H 6 , NMHC, or NMNEHC using an FTIR analyzer, verify the amount of interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. Certain species can interfere with analyzers by causing a response similar to the target analyte. If the analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. An FTIR analyzer must have combined interference that is within ±2% of the flow-weighted mean concentration of CH 4 , NMHC, or NMNEHC expected at the standard, though we strongly recommend a lower interference that is within ±1%.
(d) Procedure. Perform the interference verification for an FTIR analyzer using the same procedure that applies for N 2 O analyzers in § 1065.375(d).
§ 1065.369   H2O, CO, and CO2interference verification for photoacoustic alcohol analyzers.
(a) Scope and frequency. If you measure ethanol or methanol using a photoacoustic analyzer, verify the amount of H 2 O, CO, and CO 2 interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. H 2 O, CO, and CO 2 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, a correct result depends on simultaneously conducting 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) µmol/mol. We strongly recommend a lower interference that is within (0.0 ±0.25) µmol/mol.
(d) Procedure. Perform the interference verification by following the procedure in § 1065.375(d), comparing the results to paragraph (c) of this section.
§ 1065.370   CLD CO2and H2O quench verification.
(a) Scope and frequency. If you use a CLD analyzer to measure NO X , verify the amount of H 2 O and CO 2 quench after installing the CLD analyzer and after major maintenance.
(b) Measurement principles. H 2 O and CO 2 can negatively interfere with a CLD's NO X response by collisional quenching, which inhibits the chemiluminescent reaction that a CLD utilizes to detect NO X . This procedure and the calculations in § 1065.675 determine quench and scale the quench results to the maximum mole fraction of H 2 O and the maximum CO 2 concentration expected during emission testing. If the CLD analyzer uses quench compensation algorithms that utilize H 2 O and/or CO 2 measurement instruments, evaluate quench with these instruments active and evaluate quench with the compensation algorithms applied.
(c) System requirements. A CLD analyzer must have a combined H 2 O and CO 2 quench of ±2% or less, though we strongly recommend a quench of ±1% or less. Combined quench is the sum of the CO 2 quench determined as described in paragraph (d) of this section, plus the H 2 O quench determined in paragraph (e) of this section.
(d) CO 2 quench verification procedure. Use the following method to determine CO 2 quench by using a gas divider that blends binary span gases with zero gas as the diluent and meets the specifications in § 1065.248, or use good engineering judgment to develop a different protocol:
(1) Use PTFE or stainless steel tubing to make necessary connections.
(2) Configure the gas divider such that nearly equal amounts of the span and diluent gases are blended with each other.
(3) If the CLD analyzer has an operating mode in which it detects NO-only, as opposed to total NO X , operate the CLD analyzer in the NO-only operating mode.
(4) Use a CO 2 span gas that meets the specifications of § 1065.750 and a concentration that is approximately twice the maximum CO 2 concentration expected during emission testing.
(5) Use an NO span gas that meets the specifications of § 1065.750 and a concentration that is approximately twice the maximum NO concentration expected during emission testing.
(6) Zero and span the CLD analyzer. Span the CLD analyzer with the NO span gas from paragraph (d)(5) of this section through the gas divider. Connect the NO span gas to the span port of the gas divider; connect a zero gas to the diluent port of the gas divider; use the same nominal blend ratio selected in paragraph (d)(2) of this section; and use the gas divider's output concentration of NO to span the CLD analyzer. Apply gas property corrections as necessary to ensure accurate gas division.
(7) Connect the CO 2 span gas to the span port of the gas divider.
(8) Connect the NO span gas to the diluent port of the gas divider.
(9) While flowing NO and CO 2 through the gas divider, stabilize the output of the gas divider. Determine the CO 2 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, x CO2act , 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 CO 2 concentration. If you use an NDIR, it must meet the requirements of this part for laboratory testing and you must span it with the CO 2 span gas from paragraph (d)(4) of this section.
(10) Measure the NO concentration downstream of the gas divider with the CLD analyzer. Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response. While the analyzer measures the sample's concentration, record the analyzer's output for 30 seconds. Calculate the arithmetic mean concentration from these data, x NOmeas . Record x NOmeas , and use it in the quench verification calculations in § 1065.675.
(11) Calculate the actual NO concentration at the gas divider's outlet, x NOact , based on the span gas concentrations and x CO2act according to Eq. 1065.675-2. Use the calculated value in the quench verification calculations in Eq. 1065.675-1.
(12) Use the values recorded according to this paragraph (d) and paragraph (e) of this section to calculate quench as described in § 1065.675.
(e) H 2 O quench verification procedure. Use the following method to determine H 2 O quench, or use good engineering judgment to develop a different protocol:
(1) Use PTFE or stainless steel tubing to make necessary connections.
(2) If the CLD analyzer has an operating mode in which it detects NO-only, as opposed to total NO X , operate the CLD analyzer in the NO-only operating mode.
(3) Use an NO span gas that meets the specifications of § 1065.750 and a concentration that is near the maximum concentration expected during emission testing.
(4) Zero and span the CLD analyzer. Span the CLD analyzer with the NO span gas from paragraph (e)(3) of this section, record the span gas concentration as x NOdry , and use it in the quench verification calculations in § 1065.675.
(5) Create a humidified NO span gas by bubbling a NO gas that meets the specifications in § 1065.750 through distilled H 2 O in a sealed vessel or use a device that introduces distilled H 2 O as vapor into a controlled gas flow. If the sample does not pass through a dryer during emission testing, humidify your test gas to an H 2 O level approximately equal to the maximum mole fraction of H 2 O 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 H 2 O quench to the highest mole fraction of H 2 O expected during emission testing. If the sample passes through a dryer during emission testing, you must humidify your test gas to an H 2 O level at or above the level determined in § 1065.145(e)(2) for that dryer. For this case, the quench verification calculations in § 1065.675 do not scale the measured H 2 O quench.
(6) Introduce the humidified NO test gas into the sample system. You may introduce it upstream or downstream of any sample dryer that is used during emission testing. Note that the sample dryer must meet the sample dryer verification check in § 1065.342.
(7) Measure the mole fraction of H 2 O in the humidified NO span gas downstream of the sample dryer, x H2Omeas . We recommend that you measure x H 2Omeas as close as possible to the CLD analyzer inlet. You may calculate x H2Omeas from measurements of dew point, T dew , and absolute pressure, p total.
(8) Use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves from the point where x H2Omeas 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 x H2Omeas is measured to the analyzer are at least 5 °C above the local sample gas dew point.
(9) Measure the humidified NO span gas concentration with the CLD analyzer. Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response. While the analyzer measures the sample's concentration, record the analyzer's output for 30 seconds. Calculate the arithmetic mean of these data, x NOwet . Record x NOwet and use it in the quench verification calculations in § 1065.675.
(f) Corrective action. If the sum of the H 2 O quench plus the CO 2 quench is less than −2% or greater than + 2%, take corrective action by repairing or replacing the analyzer. Before running emission tests, verify that the corrective action successfully restored the analyzer to proper functioning.
(g) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your NO X sampling system and your emission calculation procedures, the combined CO 2 and H 2 O interference for your NO X CLD analyzer always affects your brake-specific NO X emission results within no more than ±1% of the applicable NO X standard. If you certify to a combined emission standard (such as a NO X + NMHC standard), scale your NO X results to the combined standard based on the measured results (after incorporating deterioration factors, if applicable). For example, if your final NO X + NMHC value is half of the emission standard, double the NO X result to estimate the level of NO X emissions corresponding to the applicable standard.
(2) You may use a NO X CLD analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.372   NDUV analyzer HC and H2O interference verification.
(a) Scope and frequency. If you measure NO X using an NDUV analyzer, verify the amount of H 2 O and hydrocarbon interference after initial analyzer installation and after major maintenance.
(b) Measurement principles. Hydrocarbons and H 2 O can positively interfere with an NDUV analyzer by causing a response similar to NO X . If the NDUV analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting such measurements to test the algorithms during the analyzer interference verification.
(c) System requirements. A NO X NDUV analyzer must have combined H 2 O and HC interference within ±2% of the flow-weighted mean concentration of NO X expected at the standard, though we strongly recommend keeping interference within ±1%.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the NO X NDUV analyzer according to the instrument manufacturer's instructions.
(2) We recommend that you extract engine exhaust to perform this verification. Use a CLD that meets the specifications of subpart C of this part to quantify NO X in the exhaust. Use the CLD response as the reference value. Also measure HC in the exhaust with a FID analyzer that meets the specifications of subpart C of this part. Use the FID response as the reference hydrocarbon value.
(3) Upstream of any sample dryer, if one is used during testing, introduce the engine exhaust to the NDUV analyzer.
(4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.
(5) While all analyzers measure the sample's concentration, record 30 seconds of sampled data, and calculate the arithmetic means for the three analyzers.
(6) Subtract the CLD mean from the NDUV mean.
(7) Multiply this difference by the ratio of the flow-weighted mean HC concentration expected at the standard to the HC concentration measured during the verification.
(8) The analyzer meets the interference verification of this section if the result of paragraph (d)(7) of this section meets the tolerance in paragraph (c) of this section.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your NO X sampling system and your emission calculation procedures, the combined HC and H 2 O interference for your NO X NDUV analyzer always affects your brake-specific NO X emission results by less than 0.5% of the applicable NO X standard.
(2) You may use a NO X NDUV analyzer that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.375   Interference verification for N2O analyzers.
(a) Scope and frequency. This section describes how to perform interference verification for certain analyzers as described in § 1065.275. Perform interference verification after initial analyzer installation and after major maintenance.
(b) Measurement principles. Certain species can positively interfere with analyzers by causing a response similar to N 2 O. If the analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. Analyzers must have combined interference that is within (0.0 ±1.0) µmol/mol. We strongly recommend a lower interference that is within (0.0 ±0.5) µmol/mol.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the N 2 O 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 H 2 O in a sealed vessel or use a device that introduces distilled H 2 O as vapor into a controlled gas flow. If the sample does not pass through a dryer during emission testing, humidify your test gas to an H 2 O level at or above the maximum expected during emission testing. If the sample passes through a dryer during emission testing, you must humidify your test gas to an H 2 O level at or above 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 upstream or 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 H 2 O mole fraction, x H 2 O , of the humidified interference test gas as close as possible to the inlet of the analyzer. For example, measure dewpoint, T dew , and absolute pressure, p total , to calculate x H 2 O . Verify that the H 2 O 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 H 2 O 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 H 2 O content (e.g., dewpoint and pressure) or an estimate based on the vessel pressure and temperature. Use good engineering judgment to estimate the H 2 O content. For example, you may use previous direct measurements of H 2 O 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 x H 2 O 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 x H 2 O 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 species. If the concentrations of the interference species 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 H 2 O (down to 0.025 mol/mol H 2 O content) that are lower than the maximum levels expected during testing, but you must scale up the observed H 2 O interference by multiplying the observed interference by the ratio of the maximum expected H 2 O 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.
§ 1065.376   Chiller NO2penetration.
(a) Scope and frequency. If you use a chiller to dry a sample upstream of a NO X measurement instrument, but you don't use an NO 2 -to-NO converter upstream of the chiller, you must perform this verification for chiller NO 2 penetration. Perform this verification after initial installation and after major maintenance.
(b) Measurement principles. A chiller removes H 2 O, which can otherwise interfere with a NO X measurement. However, liquid H 2 O remaining in an improperly designed chiller can remove NO 2 from the sample. If a chiller is used without an NO 2 -to-NO converter upstream, it could remove NO 2 from the sample prior NO X measurement.
(c) System requirements. A chiller must allow for measuring at least 95% of the total NO 2 at the maximum expected concentration of NO 2 .
(d) Procedure. Use the following procedure to verify chiller performance:
(1) Instrument setup. Follow the analyzer and chiller manufacturers' start-up and operating instructions. Adjust the analyzer and chiller as needed to optimize performance.
(2) Equipment setup and data collection. (i) Zero and span the total NO X gas analyzer(s) as you would before emission testing.
(ii) Select an NO 2 calibration gas, balance gas of dry air, that has an NO 2 concentration within ±5% of the maximum NO 2 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 NO X response, accounting only for transport delays and instrument response.
(iv) Calculate the mean of 30 seconds of recorded total NO X data and record this value as x NOXref .
(v) Stop flowing the NO 2 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 H 2 O.
(vii) Immediately switch back to overflowing the NO 2 calibration gas used to establish x NOxref . Allow for stabilization of the total NO X response, accounting only for transport delays and instrument response. Calculate the mean of 30 seconds of recorded total NO X data and record this value as x NOxmeas .
(viii) Correct x NOxmeas to x NOxdry based upon the residual H 2 O vapor that passed through the chiller at the chiller's outlet temperature and pressure.
(3) Performance evaluation. If x NOxdry is less than 95% of x NOxref , repair or replace the chiller.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your NO X sampling system and your emission calculations procedures, the chiller always affects your brake-specific NO X emission results by less than 0.5% of the applicable NO X standard.
(2) You may use a chiller that you determine does not meet this verification, as long as you try to correct the problem and the measurement deficiency does not adversely affect your ability to show that engines comply with all applicable emission standards.
§ 1065.377   Interference verification for NH3analyzers.
(a) Scope and frequency. This section describes how to perform interference verification for certain analyzers as described in § 1065.277. Perform interference verification after initial analyzer installation and after major maintenance.
(b) Measurement principles. Certain compounds can positively interfere with analyzers by causing a response similar to NH 3 . If the analyzer uses compensation algorithms that utilize measurements of other gases to meet this interference verification, a correct result depends on simultaneously conducting these other measurements to test the compensation algorithms during the analyzer interference verification.
(c) System requirements. Analyzers must have combined interference that is within (0.0 ±2.0) µmol/mol.
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the NH 3 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) Except as specified in paragraph (d)(9) of this section, select a multi-component span gas meeting the specification of § 1065.750 that incorporates the all the appropriate interference species. Use a humidity generator that meets the requirements in § 1065.750(a)(6) to humidify the span gas. If the sample does not pass through a dryer during emission testing, humidify your test gas to an H 2 O level at or above the maximum expected during emission testing. If the sample passes through a dryer during emission testing, humidify your test gas to an H 2 O level at or above 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 upstream or downstream of any sample dryer, if one is used during testing.
(4) If the sample does not pass through a dryer during this verification test, measure the H 2 O mole fraction, x H2O, of the humidified interference test gas as close as possible to the analyzer inlet. You may measure dewpoint, T dew, and absolute pressure, p total, to calculate x H2O. Verify that the H 2 O content meets the requirement in paragraph (d)(2) of this section. If the sample passes through a dryer during this verification test, either measure dewpoint, T dew, and absolute pressure, p total, to calculate x H2O or use good engineering judgment to estimate the value of x H2O based on the vessel pressure and temperature. For example, you may use previous direct measurements of H 2 O content at certain vessel pressures and temperatures to estimate x H2O.
(5) If the verification procedure does not include a sample dryer, use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves between the point of x H2O measurement and the analyzer. We recommend that you design your system so that the wall temperatures in those transfer lines, fittings, and valves are at least 5  °C 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) Operate the analyzer to measures the sample's NH 3 concentration and record results for 30 seconds. Calculate the arithmetic mean of these data to determine the interference value. When performed with all the interference species 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 instead perform interference verification procedures separately for individual interference species. The interference verification specified in paragraph (c) of this section applies based on the sum of the interference values from separate interference species. If the concentration of any interference species used is higher than the maximum levels expected during testing, you may scale down each observed interference value by multiplying the observed interference value by the ratio of the maximum expected concentration value to the concentration in the span gas. You may run separate H 2 O interference concentrations (down to 0.025 mol/mol H 2 O content) that are lower than the maximum levels expected during testing, but you must scale up the observed H 2 O interference value by multiplying the observed interference value by the ratio of the maximum expected H 2 O concentration value to the concentration in the span gas. The sum of the scaled interference values must meet the tolerance for combined interference as specified in paragraph (c) of this section.
§ 1065.378   NO2-to-NO converter conversion verification.
(a) Scope and frequency. If you use an analyzer that measures only NO to determine NO X , you must use an NO 2 -to-NO converter upstream of the analyzer. Perform this verification after installing the converter, after major maintenance and within 35 days before an emission test. This verification must be repeated at this frequency to verify that the catalytic activity of the NO 2 -to-NO converter has not deteriorated.
(b) Measurement principles. An NO 2 -to-NO converter allows an analyzer that measures only NO to determine total NO X by converting the NO 2 in exhaust to NO.
(c) System requirements. An NO 2 -to-NO converter must allow for measuring at least 95% of the total NO 2 at the maximum expected concentration of NO 2 .
(d) Procedure. Use the following procedure to verify the performance of a NO 2 -to-NO converter:
(1) Instrument setup. Follow the analyzer and NO 2 -to-NO converter manufacturers' start-up and operating instructions. Adjust the analyzer and converter as needed to optimize performance.
(2) Equipment setup. Connect an ozonator's inlet to a zero-air or oxygen source and connect its outlet to one port of a three-way tee fitting. Connect an NO span gas to another port, and connect the NO 2 -to-NO converter inlet to the last port.
(3) Adjustments and data collection. Perform this check as follows:
(i) Set ozonator air off, turn ozonator power off, and set the analyzer to NO mode. Allow for stabilization, accounting only for transport delays and instrument response.
(ii) Use an NO concentration that is representative of the peak total NO X concentration expected during testing. The NO 2 content of the gas mixture shall be less than 5% of the NO concentration. Record the concentration of NO by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NOref .
(iii) Turn on the ozonator O 2 supply and adjust the O 2 flow rate so the NO indicated by the analyzer is about 10 percent less than x NOref . Record the concentration of NO by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NO + O2mix .
(iv) Switch the ozonator on and adjust the ozone generation rate so the NO measured by the analyzer is 20 percent of x NOref or a value which would simulate the maximum concentration of NO 2 expected during testing, while maintaining at least 10 percent unreacted NO. This ensures that the ozonator is generating NO 2 at the maximum concentration expected during testing. Record the concentration of NO by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NOmeas .
(v) Switch the NO X analyzer to NO X mode and measure total NO X . Record the concentration of NO X by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NOxmeas .
(vi) Switch off the ozonator but maintain gas flow through the system. The NO X analyzer will indicate the NO X in the NO + O 2 mixture. Record the concentration of NO X by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NOx + O2mix .
(vii) Turn off the ozonator O 2 supply. The NO X analyzer will indicate the NO X in the original NO-in-N 2 mixture. Record the concentration of NO X by calculating the mean of 30 seconds of sampled data from the analyzer and record this value as x NOxref . This value should be no more than 5 percent above the x NOref value.
(4) Performance evaluation. Calculate the efficiency of the NO X converter by substituting the concentrations obtained into the following equation:
(5) If the result is less than 95%, repair or replace the NO 2 -to-NO converter.
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your NO X sampling system and your emission calculations procedures, the converter always affects your brake-specific NO X emission results by less than 0.5% of the applicable NO X standard.
(2) You may use a converter 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.
(3) You may request to verify converter conversion efficiency using an NO 2 concentration whose value is representative of the peak total NO 2 concentration expected during testing, in place of the procedure in paragraph (d) of this section, with our approval.
§ 1065.390   PM balance verifications and weighing process verification.
(a) Scope and frequency. This section describes three verifications.
(1) Independent verification of PM balance performance within 370 days before weighing any filter.
(2) Zero and span the balance within 12 h before weighing any filter.
(3) Verify that the mass determination of reference filters before and after a filter weighing session are less than a specified tolerance.
(b) Independent verification. Have the balance manufacturer (or a representative approved by the balance manufacturer) verify the balance performance within 370 days of testing. Balances have internal weights that compensate for drift due to environmental changes. These internal weights must be verified as part of this independent verification with external, certified calibration weights that meet the specifications in § 1065.790.
(c) Zeroing and spanning. You must verify balance performance by zeroing and spanning it with at least one calibration weight. Also, any external weights you use must meet the specifications in § 1065.790. Any weights internal to the PM balance used for this verification must be verified as described in paragraph (b) of this section.
(1) Use a manual procedure in which you zero the balance and span the balance with at least one calibration weight. If you normally use mean values by repeating the weighing process to improve the accuracy and precision of PM measurements, use the same process to verify balance performance.
(2) You may use an automated procedure to verify balance performance. For example most balances have internal weights for automatically verifying balance performance.
(d) Reference sample weighing. Verify all mass readings during a weighing session by weighing reference PM sample media (e.g., filters) before and after a weighing session. A weighing session may be as short as desired, but no longer than 80 hours, and may include both pre-test and post-test mass readings. We recommend that weighing sessions be eight hours or less. Successive mass determinations of each reference PM sample media (e.g., filter) must return the same value within ±10 µg or ±10% of the net PM mass expected at the standard (if known), whichever is higher. If successive reference PM sample media (e.g., filter) weighing events fail this criterion, invalidate all individual test media (e.g., filter) mass readings occurring between the successive reference media (e.g., filter) mass determinations. You may reweigh these media (e.g., filter) in another weighing session. If you invalidate a pre-test media (e.g., filter) mass determination, that test interval is void. Perform this verification as follows:
(1) Keep at least two samples of unused PM sample media (e.g., filters) in the PM-stabilization environment. Use these as references. If you collect PM with filters, select unused filters of the same material and size for use as references. You may periodically replace references, using good engineering judgment.
(2) Stabilize references in the PM stabilization environment. Consider references stabilized if they have been in the PM-stabilization environment for a minimum of 30 min, and the PM-stabilization environment has been within the specifications of § 1065.190(d) for at least the preceding 60 min.
(3) Exercise the balance several times with a reference sample. We recommend weighing ten samples without recording the values.
(4) Zero and span the balance. Using good engineering judgment, place a test mass such as a calibration weight on the balance, then remove it. After spanning, confirm that the balance returns to a zero reading within the normal stabilization time.
(5) Weigh each of the reference media (e.g., filters) and record their masses. We recommend using substitution weighing as described in § 1065.590(j). If you normally use mean values by repeating the weighing process to improve the accuracy and precision of the reference media (e.g., filter) mass, you must use mean values of sample media (e.g., filter) masses.
(6) Record the balance environment dewpoint, ambient temperature, and atmospheric pressure.
(7) Use the recorded ambient conditions to correct results for buoyancy as described in § 1065.690. Record the buoyancy-corrected mass of each of the references.
(8) Subtract each reference media's (e.g., filter's) buoyancy-corrected reference mass from its previously measured and recorded buoyancy-corrected mass.
(9) If any of the reference filters' observed mass changes by more than that allowed under this paragraph, you must invalidate all PM mass determinations made since the last successful reference media ( e.g. filter) mass validation. You may discard reference PM media ( e.g. filters) if only one of the filter's mass changes by more than the allowable amount and you can positively identify a special cause for that filter's mass change that would not have affected other in-process filters. Thus, the validation can be considered a success. In this case, you do not have to include the contaminated reference media when determining compliance with paragraph (d)(10) of this section, but the affected reference filter must be immediately discarded and replaced prior to the next weighing session.
(10) If any of the reference masses change by more than that allowed under this paragraph (d), invalidate all PM results that were determined between the two times that the reference masses were determined. If you discarded reference PM sample media according to paragraph (d)(9) of this section, you must still have at least one reference mass difference that meets the criteria in this paragraph (d). Otherwise, you must invalidate all PM results that were determined between the two times that the reference media (e.g., filters) masses were determined.
§ 1065.395   Inertial PM balance verifications.
This section describes how to verify the performance of an inertial PM balance.
(a) Independent verification. Have the balance manufacturer (or a representative approved by the balance manufacturer) verify the inertial balance performance within 370 days before testing.
(b) Other verifications. Perform other verifications using good engineering judgment and instrument manufacturer recommendations.
§ 1065.401   Test engine selection.
While all engine configurations within a certified engine family must comply with the applicable standards in the standard-setting part, you need not test each configuration for certification.
(a) Select an engine configuration within the engine family for testing, as follows:
(1) Test the engine that we specify, whether we issue general guidance or give you specific instructions.
(2) If we do not tell you which engine to test, follow any instructions in the standard-setting part.
(3) If we do not tell you which engine to test and the standard-setting part does not include specifications for selecting test engines, use good engineering judgment to select the engine configuration within the engine family that is most likely to exceed an emission standard.
(b) In the absence of other information, the following characteristics are appropriate to consider when selecting the engine to test:
(1) Maximum fueling rates.
(2) Maximum loads.
(3) Maximum in-use speeds.
(4) Highest sales volume.
(c) For our testing, we may select any engine configuration within the engine family.
§ 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.
(1) This includes governors that you normally install on production engines. Production engines should also be tested with their installed governors. If your engine is equipped with multiple user-selectable governor types and if the governor does not manipulate the emission control system ( i.e., the governor only modulates an “operator demand” signal such as commanded fuel rate, torque, or power), choose the governor type that allows the test cell to most accurately follow the duty cycle. If the governor manipulates the emission control system, treat it as an adjustable parameter. 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.
(2) 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.
(3) The provisions in § 1065.110(e) also apply to emission-data engines for certification.
(4) For engines using SCR, use any size DEF tank and fuel tank. We may require you to give us a production-type DEF tank, including any associated sensors, for our testing.
(b) We may set adjustable parameters to any value in the valid range, and you are responsible for controlling emissions over the full valid range. For each adjustable parameter, if the standard-setting part has no unique requirements and if we have not specified a value, use good engineering judgment to select the most common setting. If information on the most common setting is not available, select the setting representing the engine's original shipped configuration. If information on the most common and original settings is not available, set the adjustable parameter in the middle of the valid range.
(c) Testing generally occurs only after the test engine has undergone a stabilization step (or in-use operation). If the engine has not already been stabilized, run the test engine, with all emission control systems operating, long enough to stabilize emission levels. Note that you must generally use the same stabilization procedures for emission-data engines for which you apply the same deterioration factors so low-hour emission-data engines are consistent with the low-hour engine used to develop the deterioration factor.
(1) Unless otherwise specified in the standard-setting part, you may consider emission levels stable without measurement after 50 h of operation. If the engine needs less operation to stabilize emission levels, record your reasons and the methods for doing this, and give us these records if we ask for them. If the engine will be tested for certification as a low-hour engine, see the standard-setting part for limits on testing engines to establish low-hour emission levels.
(2) You may stabilize emissions from a catalytic exhaust aftertreatment device by operating it on a different engine, consistent with good engineering judgment. Note that good engineering judgment requires that you consider both the purpose of the test and how your stabilization method will affect the development and application of deterioration factors. For example, this method of stabilization is generally not appropriate for production engines. We may also allow you to stabilize emissions from a catalytic exhaust aftertreatment device by operating it on an engine-exhaust simulator.
(d) Record any maintenance, modifications, parts changes, diagnostic or emissions testing and document the need for each event. You must provide this information if we request it.
(e) For accumulating operating hours on your test engines, select engine operation that represents normal in-use operation for the engine family.
(f) If your engine will be used in a vehicle equipped with a canister for storing evaporative hydrocarbons for eventual combustion in the engine and the test sequence involves a cold-start or hot-start duty cycle, attach a canister to the engine before running an emission test. You may omit using an evaporative canister for any hot-stabilized duty cycles. You may request to omit using an evaporative canister during testing if you can show that it would not affect your ability to show compliance with the applicable emission standards. You may operate the engine without an installed canister for service accumulation. Prior to an emission test, use the following steps to precondition a canister and attach it to your engine:
(1) Use a canister and plumbing arrangement that represents the in-use configuration of the largest capacity canister in all expected applications.
(2) Precondition the canister as described in 40 CFR 86.132-96(j).
(3) Connect the canister's purge port to the engine.
(4) Plug the canister port that is normally connected to the fuel tank.
(g) This paragraph (g) 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 (g)(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. Except as specified in paragraph (g)(2) of this section, an engine-related component meeting both 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 controlling 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.
(2) This paragraph (g)(2) applies for engine-related components that meet the criteria of paragraph (g)(1) of this section, but that are part of the laboratory setup or are used for other engines. Such components are considered to be part of the test engine for preconditioning, but not for engine stabilization. For example, if you test your engines using the same laboratory exhaust tubing for all tests, there would be no restrictions on the number of test hours that could be accumulated with the tubing, but it would need to be preconditioned separately for each engine.
§ 1065.410   Maintenance limits for stabilized test engines.
(a) After you stabilize the test engine's emission levels, you may do maintenance as allowed by the standard-setting part. However, you may not do any maintenance based on emission measurements from the test engine (i.e., unscheduled maintenance).
(b) For any critical emission-related maintenance—other than what we specifically allow in the standard-setting part—you must completely test an engine for emissions before and after doing any maintenance that might affect emissions, unless we waive this requirement.
(c) If you inspect an engine, keep a record of the inspection and update your application for certification to document any changes that result. You may use any kind of equipment, instrument, or tool that is available at dealerships and other service outlets to identify malfunctioning components or perform maintenance. You may inspect using electronic tools or internal engine systems to monitor engine performance, but only if the information is readable without specialized equipment.
(d) You may repair defective parts from a test engine if they are unrelated to emission control. You must ask us to approve repairs that might affect the engine's emission controls. If we determine that a part failure, system malfunction, or associated repair makes the engine's emission controls unrepresentative of production engines, you may not use it as an emission-data engine. Also, if your test engine has a major mechanical failure that requires you to take it apart, you may no longer use it as an emission-data engine.
§ 1065.415   Durability demonstration.
If the standard-setting part requires durability testing, you must accumulate service in a way that represents how you expect the engine to operate in use. You may accumulate service hours using an accelerated schedule, such as through continuous operation or by using duty cycles that are more aggressive than in-use operation, subject to any pre-approval requirements established in the applicable standard-setting part.
(a) Maintenance. The following limits apply to the maintenance that we allow you to do on an emission-data engine:
(1) You may perform scheduled maintenance that you recommend to operators, but only if it is consistent with the standard-setting part's restrictions.
(2) You may perform additional maintenance only as specified in § 1065.410 or allowed by the standard-setting part.
(b) Emission measurements. Perform emission tests following the provisions of the standard setting part and this part, as applicable. Perform emission tests to determine deterioration factors consistent with good engineering judgment. Evenly space any tests between the first and last test points throughout the durability period, unless we approve otherwise.
§ 1065.501   Overview.
(a) Use the procedures detailed in this subpart to measure engine emissions over a specified duty cycle. Refer to subpart J of this part for field test procedures that describe how to measure emissions during in-use engine operation. Refer to subpart L of this part for measurement procedures for testing related to standards other than brake-specific emission standards. This section describes how to—
(1) Map your engine, if applicable, by recording specified speed and torque data, as measured from the engine's primary output shaft.
(2) Transform normalized duty cycles into reference duty cycles for your engine by using an engine map.
(3) Prepare your engine, equipment, and measurement instruments for an emission test.
(4) Perform pre-test procedures to verify proper operation of certain equipment and analyzers.
(5) Record pre-test data.
(6) Start or restart the engine and sampling systems.
(7) Sample emissions throughout the duty cycle.
(8) Record post-test data.
(9) Perform post-test procedures to verify proper operation of certain equipment and analyzers.
(10) Weigh PM samples.
(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 also allows you to ensure that a regeneration event does not occur during an emission test.
(c) An emission test generally consists of measuring emissions and other parameters while an engine follows one or more duty cycles that are specified in the standard-setting part. There are two general types of duty cycles:
(1) Transient cycles. Transient duty cycles are typically specified in the standard-setting part as a second-by-second sequence of speed commands and normalized torque (or power) commands. Operate an engine over a transient cycle such that the speed and torque of the engine's primary output shaft follows the target values. Proportionally sample emissions and other parameters and use the calculations in subpart G of this part to calculate emissions. Start a transient test according to the standard-setting part, as follows:
(i) A cold-start transient cycle where you start to measure emissions just before starting an engine that has not been warmed up.
(ii) A hot-start transient cycle where you start to measure emissions just before starting a warmed-up engine.
(iii) A hot running transient cycle where you start to measure emissions after an engine is started, warmed up, and running.
(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:
(i) Discrete-mode cycles. Before emission sampling, stabilize an engine at the first discrete mode of the duty cycle specified in the standard-setting part. Sample emissions and other parameters for that mode in the same manner as a transient cycle, with the exception that reference speed and torque values are constant. Record data for that mode, transition to the next mode, and then stabilize the engine at the next mode. Continue to sample each mode discretely as a separate test interval and calculate composite brake-specific emission results according to § 1065.650(g)(2).
(A) Use good engineering judgment to determine the time required to stabilize the engine. You may make this determination before starting the test based on prior experience, or you may make this determination in real time based an automated stability criteria. If needed, you may continue to operate the engine after reaching stability to get laboratory equipment ready for sampling.
(B) Collect PM on separate PM sample media for each mode.
(C) The minimum sample time is 60 seconds. We recommend that you sample both gaseous and PM emissions over the same test interval. If you sample gaseous and PM emissions over different test intervals, there must be no change in engine operation between the two test intervals. These two test intervals may completely or partially overlap, they may run consecutively, or they may be separated in time.
(ii) Ramped-modal cycles. Perform ramped-modal cycles similar to the way you would perform transient cycles, except that ramped-modal cycles involve mostly steady-state engine operation. Generate a ramped-modal duty cycle as a sequence of second-by-second (1 Hz) reference speed and torque points. Run the ramped-modal duty cycle in the same manner as a transient cycle and use the 1 Hz reference speed and torque values to validate the cycle, even for cycles with % power. Proportionally sample emissions and other parameters during the cycle and use the calculations in subpart G of this part to calculate emissions.
(d) Other subparts in this part identify how to select and prepare an engine for testing (subpart E), how to perform the required engine service accumulation (subpart E), and how to calculate emission results (subpart G).
(e) Subpart J of this part describes how to perform field testing.