verification in Sec.  1065.369 and it must also meet the linearity
verification in Sec.  1065.307. Use an optical wheel configuration that
gives analytical priority to measurement of the least stable components
in the sample. Select a sample integration time of at least 5 seconds.
Take into account sample chamber and sample line volumes when
determining flush times for your instrument.

0
263. Section 1065.270 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.270  Chemiluminescent detector.

* * * * *
    (b) Component requirements. We recommend that you use a CLD that
meets the specifications in Table 1 of Sec.  1065.205. Note that your
CLD-based system must meet the quench verification in Sec.  1065.370
and it must also meet the linearity verification in Sec.  1065.307. You
may use a heated or unheated CLD, and you may use a CLD that operates
at atmospheric pressure or under a vacuum.
* * * * *

0
264. Section 1065.272 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.272  Nondispersive ultraviolet analyzer.

* * * * *
    (b) Component requirements. We recommend that you use an NDUV
analyzer that meets the specifications in Table 1 of Sec.  1065.205.
Note that your NDUV-based system must meet the verifications in Sec.
1065.372 and it must also meet the linearity verification in Sec.
1065.307.
* * * * *

0
265. Section 1065.275 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.275  N[bdi2]O measurement devices.

* * * * *
    (b) Instrument types. You may use any of the following analyzers to
measure N2O:
    (1) Nondispersive infrared (NDIR) analyzer.
    (2) Fourier transform infrared (FTIR) analyzer. Use appropriate
analytical procedures for interpretation of infrared spectra. For
example, EPA Test Method

320 is considered a valid method for spectral interpretation (see
http://www.epa.gov/ttn/emc/methods/method320.html).
    (3) Laser infrared analyzer. Examples of laser infrared analyzers
are pulsed-mode high-resolution narrow band mid-infrared analyzers, and
modulated continuous wave high-resolution narrow band mid-infrared
analyzers.
    (4) Photoacoustic analyzer. Use an optical wheel configuration that
gives analytical priority to measurement of the least stable components
in the sample. Select a sample integration time of at least 5 seconds.
Take into account sample chamber and sample line volumes when
determining flush times for your instrument.
    (5) Gas chromatograph analyzer. You may use a gas chromatograph
with an electron-capture detector (GC-ECD) to measure N2O
concentrations of diluted exhaust for batch sampling.
    (i)You may use a packed or porous layer open tubular (PLOT) column
phase of suitable polarity and length to achieve adequate resolution of
the N2O peak for analysis. Examples of acceptable columns
are a PLOT column consisting of bonded polystyrene-divinylbenzene or a
Porapack Q packed column. Take the column temperature profile and
carrier gas selection into consideration when setting up your method to
achieve adequate N2O peak resolution.
    (ii) Use good engineering judgment to zero your instrument and
correct for drift. You do not need to follow the specific procedures in
Sec. Sec.  1065.530 and 1065.550(b) that would otherwise apply. For
example, you may perform a span gas measurement before and after sample
analysis without zeroing and use the average area counts of the pre-
span and post-span measurements to generate a response factor (area
counts/span gas concentration), which you then multiply by the area
counts from your sample to generate the sample concentration.
* * * * *

0
266. Section 1065.280 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.280  Paramagnetic and magnetopneumatic O[bdi2] detection
analyzers.

* * * * *
    (b) Component requirements. We recommend that you use a PMD or MPD
analyzer that meets the specifications in Table 1 of Sec.  1065.205.
Note that it must meet the linearity verification in Sec.  1065.307.

0
267. Section 1065.284 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.284  Zirconia (ZrO[bdi2]) analyzer.

* * * * *
    (b) Component requirements. We recommend that you use a
ZrO2 analyzer that meets the specifications in Table 1 of
Sec.  1065.205. Note that your ZrO2-based system must meet
the linearity verification in Sec.  1065.307.

0
268. Section 1065.295 is amended by revising paragraph (b) to read as
follows:

Sec.  1065.295  PM inertial balance for field-testing analysis.

* * * * *
    (b) Component requirements. We recommend that you use a balance
that meets the specifications in Table 1 of Sec.  1065.205. Note that
your balance-based system must meet the linearity verification in Sec.
1065.307. If the balance uses an internal calibration process for
routine spanning and linearity verifications, the process must be NIST-
traceable.
* * * * *

Subpart D--[Amended]

0
269. Section 1065.303 is revised to read as follows:

Sec.  1065.303  Summary of required calibration and verifications.

    The following table summarizes the required and recommended
calibrations and verifications described in this subpart and indicates
when these have to be performed:

     Table 1 of Sec.   1065.303--Summary of Required Calibration and
                              Verifications
------------------------------------------------------------------------
  Type of calibration or verification         Minimum frequency \1\
------------------------------------------------------------------------
Sec.   1065.305: Accuracy,               Accuracy: Not required, but
 repeatability and noise.                 recommended for initial
                                          installation.
                                         Repeatability: Not required,
                                          but recommended for initial
                                          installation.
                                         Noise: Not required, but
                                          recommended for initial
                                          installation.
Sec.   1065.307: Linearity verification  Speed: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.
                                         Torque: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.
                                         Electrical power, current, and
                                          voltage: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.\2\
                                         Fuel flow rate: Upon initial
                                          installation, within 370 days
                                          before testing, and after
                                          major maintenance.
                                         Intake-air, dilution air,
                                          diluted exhaust, and batch
                                          sampler flow rates: Upon
                                          initial installation, within
                                          370 days before testing and
                                          after major maintenance,
                                          unless flow is verified by
                                          propane check or by carbon or
                                          oxygen balance.
                                         Raw exhaust flow rate: Upon
                                          initial installation, within
                                          185 days before testing and
                                          after major maintenance,
                                          unless flow is verified by
                                          propane check or by carbon or
                                          oxygen balance.
                                         Gas dividers: Upon initial
                                          installation, within 370 days
                                          before testing, and after
                                          major maintenance.
                                         Gas analyzers (unless otherwise
                                          noted): Upon initial
                                          installation, within 35 days
                                          before testing and after major
                                          maintenance.
                                         FTIR and photoacoustic
                                          analyzers: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.
                                         GC-ECD: Upon initial
                                          installation and after major
                                          maintenance.
                                         PM balance: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.
                                         Pressure, temperature, and
                                          dewpoint: Upon initial
                                          installation, within 370 days
                                          before testing and after major
                                          maintenance.
Sec.   1065.308: Continuous gas          Upon initial installation or
 analyzer system response and updating-   after system modification that
 recording verification--for gas          would affect response.
 analyzers not continuously compensated
 for other gas species.

Sec.   1065.309: Continuous gas          Upon initial installation or
 analyzer system-response and updating-   after system modification that
 recording verification--for gas          would affect response.
 analyzers continuously compensated for
 other gas species.
Sec.   1065.310: Torque................  Upon initial installation and
                                          after major maintenance.
Sec.   1065.315: Pressure, temperature,  Upon initial installation and
 dewpoint.                                after major maintenance.
Sec.   1065.320: Fuel flow.............  Upon initial installation and
                                          after major maintenance.
Sec.   1065.325: Intake flow...........  Upon initial installation and
                                          after major maintenance.
Sec.   1065.330: Exhaust flow..........  Upon initial installation and
                                          after major maintenance.
Sec.   1065.340: Diluted exhaust flow    Upon initial installation and
 (CVS).                                   after major maintenance.
Sec.   1065.341: CVS and batch sampler   Upon initial installation,
 verification \3\.                        within 35 days before testing,
                                          and after major maintenance.
Sec.   1065.342 Sample dryer             For thermal chillers: upon
 verification.                            installation and after major
                                          maintenance.
                                         For osmotic membranes; upon
                                          installation, within 35 days
                                          of testing, and after major
                                          maintenance.
Sec.   1065.345: Vacuum leak...........  For laboratory testing: upon
                                          initial installation of the
                                          sampling system, 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: 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.
Sec.   1065.350: CO2 NDIR H2O            Upon initial installation and
 interference.                            after major maintenance.
Sec.   1065.355: CO NDIR CO2 and H2O     Upon initial installation and
 interference.                            after major maintenance.
Sec.   1065.360: FID calibration.......  Calibrate all FID analyzers:
THC FID optimization, and THC FID         upon initial installation and
 verification.                            after major maintenance.
                                         Optimize and determine CH4
                                          response for THC FID
                                          analyzers:
                                         upon initial installation and
                                          after major maintenance.
                                         Verify CH4 response for THC FID
                                          analyzers: upon initial
                                          installation, within 185 days
                                          before testing, and after
                                          major maintenance.
Sec.   1065.362: Raw exhaust FID O2      For all FID analyzers: upon
 interference.                            initial installation, and
                                          after major maintenance.
                                         For THC FID analyzers: upon
                                          initial installation, after
                                          major maintenance, and after
                                          FID optimization according to
                                          Sec.   1065.360.
Sec.   1065.365: Nonmethane cutter       Upon initial installation,
 penetration.                             within 185 days before
                                          testing, and after major
                                          maintenance.
Sec.   1065.369: H2O, CO, and CO2        Upon initial installation and
 interference verification for ethanol    after major maintenance.
 photoacoustic analyzers.
Sec.   1065.370: CLD CO2 and H2O quench  Upon initial installation and
                                          after major maintenance.
Sec.   1065.372: NDUV HC and H2O         Upon initial installation and
 interference.                            after major maintenance.
Sec.   1065.375: N2O analyzer            Upon initial installation and
 interference.                            after major maintenance.
Sec.   1065.376: Chiller NO2             Upon initial installation and
 penetration.                             after major maintenance.
Sec.   1065.378: NO2-to-NO converter     Upon initial installation,
 conversion.                              within 35 days before testing,
                                          and after major maintenance.
Sec.   1065.390: PM balance and          Independent verification: upon
 weighing.                                initial installation, within
                                          370 days before testing, and
                                          after major maintenance.
                                         Zero, span, and reference
                                          sample verifications: within
                                          12 hours of weighing, and
                                          after major maintenance.
Sec.   1065.395: Inertial PM balance     Independent verification: upon
 and weighing.                            initial installation, within
                                          370 days before testing, and
                                          after major maintenance.
                                         Other verifications: upon
                                          initial installation and after
                                          major maintenance.
------------------------------------------------------------------------
\1\ Perform calibrations and verifications more frequently than we
  specify, according to measurement system manufacturer instructions and
  good engineering judgment.
\2\ Perform linearity verification either for electrical power or for
  current and voltage.
\3\ The CVS verification described in Sec.   1065.341 is not required
  for systems that agree within 2% based on a chemical
  balance of carbon or oxygen of the intake air, fuel, and diluted
  exhaust.

0
270. Section 1065.305 is amended by revising paragraph (d)(10)(i) to
read as follows:

Sec.  1065.305  Verifications for accuracy, repeatability, and noise.

* * * * *
    (d) * * *
    (10) * * *
    (i) Your measurement systems meet all the other required
calibration, verification, and validation specifications that apply as
specified in the regulations.
* * * * *

0
271. Section 1065.307 is revised to read as follows:

Sec.  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 Sec.  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.
    (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 Sec.  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 Sec.  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, yrefi, 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 Sec.  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 Sec.  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, yi. Refer to Sec.  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, yi, and reference values, yrefi, 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 described in Sec.
1065.602. Using good engineering judgment, you may weight the results
of individual data pairs (i.e. (yrefi, yi,)), 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 Sec.  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 rate. Operate the engine at a series of constant fuel-flow
rates or re-circulate fuel back to a tank through the fuel flow meter
at different flow rates. Use a gravimetric reference measurement (such
as a scale, balance, or mass comparator) at the inlet to the fuel-
measurement system. Use a stopwatch or timer to measure the time
intervals over which reference masses of fuel are introduced to the
fuel measurement system. The reference fuel mass divided by the time
interval is the reference fuel flow rate.
    (5) Flow rates--inlet air, dilution air, diluted exhaust, raw
exhaust, or sample flow. Use a reference flow meter with a blower or
pump to simulate flow rates. Use a restrictor, diverter valve, a
variable-speed blower or a variable-speed pump to control the range of
flow rates. Use the reference meter's response as the reference values.
    (i) Reference flow meters. Because the flow range requirements for
these various flows are large, we allow a variety of reference meters.
For

example, for diluted exhaust flow for a full-flow dilution system, we
recommend a reference subsonic venturi flow meter with a restrictor
valve and a blower to simulate flow rates. For inlet air, dilution air,
diluted exhaust for partial-flow dilution, raw exhaust, or sample flow,
we allow reference meters such as critical flow orifices, critical flow
venturis, laminar flow elements, master mass flow standards, or Roots
meters. Make sure the reference meter is calibrated 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 nrefi for
30 seconds and use the arithmetic mean of the values, nref,
as the reference value. Refer to Sec.  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 Sec.  1065.750. We recommend
using a FID analyzer or a PMD or MPD O2 analyzer because of
their inherent linearity. Operate this analyzer consistent with how you
would operate it during an emission test. Connect a span gas to the
gas-divider inlet. Use the gas-division system to divide the span gas
with purified air or nitrogen. Select gas divisions that you typically
use. Use a selected gas division as the measured value. Use the
analyzer response divided by the span gas concentration as the
reference gas-division value. Because the instrument response is not
absolutely constant, sample and record values of xref for 30
seconds and use the arithmetic mean of the values, xref, as
the reference value. Refer to Sec.  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 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 Sec.  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 Tmax. If you use this option, you
must use sensors that the supplier states are accurate to better than
0.5% of Tmax compared with their standard calibration curve.
    (9) Mass. For linearity verification for gravimetric PM balances,
use external calibration weights that meet the requirements in Sec.
1065.790.
    (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 ``xmin'' 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, a0. 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, xmin is -1 kPa. If the
reference values used to validate a temperature device vary from 290 to
390 K, xmin 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 a0 and SEE. For
example, if the reference values chosen to validate a pressure
transducer vary from -10 to -1 kPa, then pmax is +10 kPa. If
the reference values used to validate a temperature device vary from
290 to 390 K, then Tmax is 390 K. For gas dividers where
``max'' is expressed as, xmax/xspan;
xmax is the maximum gas concentration used during the
verification, xspan 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 with a PM balance, mmax
refers to the typical mass of a PM filter.
    (ii) For linearity verification of torque on the engine's primary
output shaft, Tmax refers to the manufacturer's specified
engine torque peak value of the lowest torque engine to be tested.
    (4) The specified ranges are inclusive. For example, a specified
range of 0.98-1.02 for a1 means 0.98<=a1<=1.02.
    (5) Linearity verification is optional for systems that pass the
flow-rate verification for diluted exhaust as described in Sec.
1065.341 (the propane check) or for systems that agree within 2% based on a chemical balance of carbon or oxygen of the intake
air, fuel, and exhaust.
    (6) You must meet the a1 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 [deg]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.
    (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 Sec.  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.

               Table 1 of Sec.   1065.307--Measurement Systems That Require Linearity Verification
----------------------------------------------------------------------------------------------------------------
                                                                        Linearity criteria
      Measurement system            Quantity    ----------------------------------------------------------------
                                                   xmin(a1-1)+a 0         a1             SEE            r \2\
----------------------------------------------------------------------------------------------------------------
Speed.........................  fn.............  <= 0.05% [middot]     0.98-1.02  <= 2% [middot]        >= 0.990
                                                  fnmax.                           fnmax.
Torque........................  T..............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  Tmax.                            Tmax.
Electrical power..............  P..............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  Pmax                             Pmax
Current.......................  I..............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  Imax                             Imax
Voltage.......................  U..............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  Umax.                            Umax.
Fuel flow rate................  mb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  mbmax.                           mbmax.
Intake-air....................  nb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
 flow rate\1\.................                    nbmax.                           nbmax.
Dilution air flow rate \1\....  nb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  nbmax.                           nbmax.
Diluted exhaust flow rate \1\.  nb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  nbmax.                           nbmax.
Raw exhaust flow rate \1\.....  nb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  nbmax.                           nbmax.
Batch sampler flow rates \1\..  nb.............  <= 1% [middot]        0.98-1.02  <= 2% [middot]        >= 0.990
                                                  nbmax.                           nbmax.
Gas dividers..................  x/xspan........  <= 0.5% [middot]      0.98-1.02  <= 2% [middot]        >= 0.990
                                                  xmax/xspan.                      xmax/xspan.
Gas analyzers for laboratory    x..............  <= 0.5% [middot]      0.99-1.01  <= 1% [middot]        >= 0.998
 testing.                                         xmax.                            xmax.
Gas analyzers for field         x..............  <= 1% [middot]        0.99-1.01  <= 1% [middot]        >= 0.998
 testing.                                         xmax.                            xmax.
PM balance....................  m..............  <= 1% [middot]        0.99-1.01  <= 1% [middot]        >= 0.998
                                                  mmax.                            mmax.
Pressures.....................  p..............  <= 1% [middot]        0.99-1.01  <= 1% [middot]        >= 0.998
                                                  pmax.                            pmax.
Dewpoint for intake air, PM-    Tdew...........  <= 0.5% [middot]      0.99-1.01  <= 0.5% [middot]      >= 0.998
 stabilization and balance                        Tdewmax.                         Tdewmax.
 environments.
Other dewpoint measurements...  Tdew...........  <= 1% [middot]        0.99-1.01  <= 1% [middot]        >= 0.998
                                                  Tdewmax-.                        Tdewmax-.
Analog-to-digital conversion    T..............  <= 1% [middot]        0.99-1.01  <= 1% [middot]        >= 0.998
 of temperature signals.                          Tmax.                            Tmax.
----------------------------------------------------------------------------------------------------------------
\1\ For flow meters that determine volumetric flow rate, Vbstd, you may substitute Vbstd for nb as the quantity
  and substitute Vbstdmax for nbmax.

0
272. Section 1065.308 is amended by revising paragraph (d)(2) and
adding paragraph (g) to read as follows:

Sec.  1065.308  Continuous gas analyzer system-response and updating-
recording verification--for gas analyzers not continuously compensated
for other gas species.

* * * * *
    (d) * * *
    (2) Equipment setup. We recommend using minimal lengths of gas
transfer lines between all connections and fast-acting three-way valves
(2 inlets, 1 outlet) to control the flow of zero and blended span gases
to the sample system's probe inlet or a tee near the outlet of the
probe. If you inject the gas at a tee near the outlet of the probe, you
may correct the transformation time, t50, for an estimate of
the transport time from the probe inlet to the tee. Normally the gas
flow rate is higher than the sample flow rate and the excess is
overflowed out the inlet of the probe. If the gas flow rate is lower
than the sample flow rate, the gas concentrations must be adjusted to
account for the dilution from ambient air drawn into the probe. We
recommend you use the final, stabilized analyzer reading as the final
gas concentration. Select span gases for the species being measured.
You may use binary or multi-gas span gases. You may use a gas blending
or mixing device to blend span gases. A gas blending or mixing device
is recommended when blending span gases diluted in N2 with
span gases diluted in air. You may use a multi-gas span gas, such as
NO-CO-CO2-C3H8-CH4, to
verify multiple analyzers at the same time. If you use standard binary
span gases, you must run separate response tests for each analyzer. In
designing your experimental setup, avoid pressure pulsations due to
stopping the flow through the gas-blending device. The change in gas
concentration must be at least 20% of the analyzer's range.
* * * * *
    (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 N2 as the
zero gas and ambient air (plus purified N2 if needed) as the
reference gas. Perform the verification with seven repeat measurements
that each consist of stabilizing with purified N2, switching
to ambient air and observing the analyzer's rise and stabilized
reading, followed by switching back to purified N2 and
observing the analyzer's fall and stabilized reading.

0
273. Section 1065.309 is amended by revising paragraphs (a) and (d)(2)
and adding paragraphs (g) and (h) to read as follows:

Sec.  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 Sec.  1065.308 for
verification procedures that apply to continuous gas analyzers that are
not continuously compensated for other gas species or that use only one
detector for gaseous species. Perform this verification to determine
the system response of the continuous gas analyzer and its sampling
system. This verification is required for continuous gas analyzers used
for transient or ramped-modal testing. You need not perform this
verification for batch gas analyzers or for continuous gas analyzers
that are used only for discrete-mode testing. For this check we
consider water vapor a gaseous constituent. This verification does not
apply to any processing of individual analyzer signals that are time-
aligned to their t50 times and were verified according to
Sec.  1065.308. For example, this verification does not apply to
correction for water removed from the sample done in post-processing
according to Sec.  1065.659 (40 CFR 1066.620 for vehicle testing) and
it does not apply to NMHC determination from THC and CH4
according to Sec.  1065.660. Perform this verification after initial
installation (i.e., test cell commissioning) and after any
modifications to the system that would change the system response.
* * * * *
    (d) * * *
    (2) Equipment setup. We recommend using minimal lengths of gas
transfer lines between all connections and fast-acting three-way valves
(2 inlets, 1 outlet) to control the flow of zero and blended span gases
to the sample system's probe inlet or a tee near the outlet of the
probe. If you inject the gas at a tee near the outlet of the probe, you
may correct the transformation time, t50, for an estimate of
the transport time from the probe inlet to the tee. Normally the gas
flow rate is higher than the sample flow rate and the excess is
overflowed out the inlet of the probe. If the gas flow rate is lower
than the sample flow rate, the gas concentrations must be adjusted to
account for the dilution from ambient air drawn into the probe. We
recommend you use the final, stabilized analyzer reading as the final
gas concentration. Select span gases for the species being continuously
combined, other than H2O. Select concentrations of
compensating species that will yield concentrations of these species at
the analyzer inlet that covers the range of concentrations expected
during testing. You may use binary or multi-gas span gases. You may use
a gas blending or mixing device to blend span gases. A gas blending or
mixing device is recommended when blending span gases diluted in
N2 with span gases diluted in air. You may use a multi-gas
span gas, such as NO-CO-CO2-C3H8-
CH4, to verify multiple analyzers at the same time. In
designing your experimental setup, avoid pressure pulsations due to
stopping the flow through the gas blending device. The change in gas
concentration must be at least 20% of the analyzer's range. If
H2O correction is applicable, then span gases must be
humidified before entering the analyzer; however, you may not humidify
NO2 span gas by passing it through a sealed humidification
vessel that contains water. You must humidify NO2 span gas
with another moist gas stream. We recommend humidifying your NO-CO-
CO2-C3H8-CH4, balance
N2 blended gas by flowing the gas mixture through a sealed
vessel that humidifies the gas by bubbling it through distilled water
and then mixing the gas with dry NO2 gas, balance purified
air. If your system does not use a sample dryer to remove water from
the sample gas, you must humidify your span gas to the highest sample
H2O content that you estimate during emission sampling. If
your system uses a sample dryer during testing, it must pass the sample
dryer verification check in Sec.  1065.342, and you must humidify your
span gas to an H2O content greater than or equal to the
level determined in Sec.  1065.145(e)(2). If you are humidifying span
gases without NO2, use good engineering judgment to ensure
that the wall temperatures in the transfer lines, fittings, and valves
from the humidifying system to the probe are above the dewpoint
required for the target H2O content. If you are humidifying
span gases with NO2, use good engineering judgment to ensure
that there is no condensation in the transfer lines, fittings, or
valves from the point where humidified gas is mixed with NO2
span gas to the probe. We recommend that you design your setup so that
the wall temperatures in the transfer lines, fittings, and valves from
the humidifying system to the probe are at least 5 [deg]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.
* * * * *
    (g) Optional procedure. Follow the optional procedures in Sec.
1065.308(g), noting that you may use compensating gases mixed with
ambient air for oxygen analyzers.
    (h) Analyzers with H2O compensation sampling downstream of a sample
dryer. You may omit humidifying the span gas as described in this
paragraph (h). If an analyzer compensates only for H2O, you
may apply the requirements of Sec.  1065.308 instead of the
requirements of this section. You may omit humidifying the span gas if
you meet the following conditions:

    (1) The analyzer is located downstream of a sample dryer.
    (2) The maximum value for H2O mole fraction downstream
of the dryer must be less than or equal to 0.010. Verify this during
each sample dryer verification according to Sec.  1065.342.

0
274. Section 1065.310 is revised to read as follows:

Sec.  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 Sec.  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.

0
275. Section 1065.315 is amended by revising paragraph (a)(2) to read
as follows:

Sec.  1065.315  Pressure, temperature, and dewpoint calibration.

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

0
276. Section 1065.341 is amended by revising the section heading and
paragraphs (a) introductory text, (d) introductory text, and (f)(3) to
read as follows:

Sec.  1065.341  CVS, PFD, and batch sampler verification (propane
check).

    (a) A propane check serves as a CVS verification to determine if
there is a discrepancy in measured values of diluted exhaust flow. You
may use the same procedure to verify PFDs and batch samplers. For
purposes of PFD and batch sampler verification, read the term CVS to
mean PFD or batch sampler as appropriate. A propane check also serves
as a batch-sampler verification to determine if there is a discrepancy
in a batch sampling system that extracts a sample from a CVS, as
described in paragraph (g) of this section. Using good engineering
judgment and safe practices, this check may be performed using a gas
other than propane, such as CO2 or CO. A failed propane
check might indicate one or more problems that may require corrective
action, as follows:
* * * * *
    (d) If you performed the vacuum-side leak verification of the HC
sampling system as described in paragraph (c)(8) of this section, you
may use the HC contamination procedure in Sec.  1065.520(f) to verify
HC contamination. Otherwise, zero, span, and verify contamination of
the HC sampling system, as follows:
* * * * *
    (f) * * *
    (3) Calculate total C3H8 mass based on your
CVS and HC data as described in Sec.  1065.650 (40 CFR 1066.605 for
vehicle testing) and Sec.  1065.660, using the molar mass of
C3H8, MC3H8, instead the effective
molar mass of HC, MHC.
* * * * *

0
277. Section 1065.350 is amended by revising paragraph (d) and adding
paragraph (e) to read as follows:

Sec.  1065.350  H[bdi2]O interference verification for CO[bdi2] NDIR
analyzers.

* * * * *
    (d) Procedure. Perform the interference verification as follows:
    (1) Start, operate, zero, and span the CO2 NDIR analyzer
as you would before an emission test. If the sample is passed through a
dryer during emission testing, you may run this verification test with
the dryer if it meets the requirements of Sec.  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 Sec.  1065.750 through distilled H2O
in a sealed vessel. If the sample is not passed through a dryer during
emission testing, control the vessel temperature to generate an
H2O level at least as high as the maximum expected during
emission testing. If the sample is passed through a dryer during
emission testing, control the vessel temperature to generate an
H2O level at

least as high as the level determined in Sec.  1065.145(e)(2) for that
dryer.
    (3) Introduce the humidified test gas into the sample system. You
may introduce it downstream of any sample dryer, if one is used during
testing.
    (4) If the sample is not passed through a dryer during this
verification test, measure the H2O mole fraction,
xH2O, of the humidified test gas, as close as possible to
the inlet of the analyzer. For example, measure dewpoint,
Tdew, and absolute pressure, ptotal, to calculate
xH2O. Verify that the H2O content meets the
requirement in paragraph (d)(2) of this section. If the sample is
passed through a dryer during this verification test, you must verify
that the H2O content of the humidified test gas downstream
of the vessel meets the requirement in paragraph (d)(2) of this section
based on either direct measurement of the H2O content (e.g.,
dewpoint and pressure) or an estimate based on the vessel pressure and
temperature. Use good engineering judgment to estimate the
H2O content. For example, you may use previous direct
measurements of H2O content to verify the vessel's level of
saturation.
    (5) If a sample dryer is not used in this verification test, use
good engineering judgment to prevent condensation in the transfer
lines, fittings, or valves from the point where xH2O is
measured to the analyzer. We recommend that you design your system so
the wall temperatures in the transfer lines, fittings, and valves from
the point where xH2O is measured to the analyzer are at
least 5 [deg]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) While the analyzer measures the sample's concentration, record
30 seconds of sampled data. Calculate the arithmetic mean of this data.
The analyzer meets the interference verification if this value is
within (0.0 0.4) mmol/mol.
    (e) Exceptions. The following exceptions apply:
    (1) You may omit this verification if you can show by engineering
analysis that for your CO2 sampling system and your
emission-calculation procedures, the H2O interference for
your CO2 NDIR analyzer always affects your brake-specific
emission results within 0.5% of each of the applicable
standards. This specification also applies for vehicle testing, except
that it relates to emission results in g/mile or g/kilometer.
    (2) You may use a CO2 NDIR analyzer that you determine
does not meet this verification, as long as you try to correct the
problem and the measurement deficiency does not adversely affect your
ability to show that engines comply with all applicable emission
standards.
0
278. Section 1065.355 is amended by revising paragraphs (d)(2) and
(d)(4) to read as follows:

Sec.  1065.355  H[bdi2]O and CO[bdi2] interference verification for CO
NDIR analyzers.

* * * * *
    (d) * * *
    (2) Create a humidified CO2 test gas by bubbling a
CO2 span gas that meets the specifications in Sec.  1065.750
through distilled H2O in a sealed vessel. If the sample is
not passed through a dryer during emission testing, control the vessel
temperature to generate an H2O level at least as high as the
maximum expected during emission testing. If the sample is passed
through a dryer during emission testing, control the vessel temperature
to generate an H2O level at least as high as the level
determined in Sec.  1065.145(e)(2) for that dryer. Use a CO2
span gas concentration at least as high as the maximum expected during
testing.
* * * * *
    (4) If the sample is not passed through a dryer during this
verification test, measure the H2O mole fraction,
xH2O, of the humidified CO2 test gas as close as
possible to the inlet of the analyzer. For example, measure dewpoint,
Tdew, and absolute pressure, ptotal, to calculate
xH2O. Verify that the H2O content
meets the requirement in paragraph (d)(2) of this section. If the
sample is passed through a dryer during this verification test, you
must verify that the H2O content of the humidified test gas
downstream of the vessel meets the requirement in paragraph (d)(2) of
this section based on either direct measurement of the H2O
content (e.g., dewpoint and pressure) or an estimate based on the
vessel pressure and temperature. Use good engineering judgment to
estimate the H2O content. For example, you may use previous
direct measurements of H2O content to verify the vessel's
level of saturation.
* * * * *
    279. Section 1065.360 is amended by revising paragraphs (a)(3),
(b), (d), and (e) to read as follows:

Sec.  1065.360  FID optimization and verification.

    (a) * * *
    (3) Verify the CH4 response within 185 days before
testing as described in paragraph (e) of this section.
    (b) Calibration. Use good engineering judgment to develop a
calibration procedure, such as one based on the FID-analyzer
manufacturer's instructions and recommended frequency for calibrating
the FID. Alternately, you may remove system components for off-site
calibration. For a FID that measures THC, calibrate using
C3H8 calibration gases that meet the
specifications of Sec.  1065.750. For a FID that measures
CH4, calibrate using CH4 calibration gases that
meet the specifications of Sec.  1065.750. We recommend FID analyzer
zero and span gases that contain approximately the flow-weighted mean
concentration of O2 expected during testing. If you use a
FID to measure CH4 downstream of a nonmethane cutter, you
may calibrate that FID using CH4 calibration gases with the
cutter. Regardless of the calibration gas composition, calibrate on a
carbon number basis of one (C1). For example, if you use a
C3H8 span gas of concentration 200 [mu]mol/mol,
span the FID to respond with a value of 600 [mu]mol/mol. As another
example, if you use a CH4 span gas with a concentration of
200 [mu]mol/mol, span the FID to respond with a value of 200 [mu]mol/
mol.
* * * * *
    (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 CH4 versus
C3H8, determine each THC-FID analyzer's
CH4 response factor, RF CH4[THC-FID], after FID
optimization. Use the most recent RFCH4[THC-FID] measured
according to this section in the calculations for HC determination
described in Sec.  1065.660 to compensate for CH4 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 CH4 with a nonmethane cutter:
    (1) Select a C3 H8 span gas concentration
that you use to span your analyzers before emission testing. Use only
span gases that meet the specifications of Sec.  1065.750. Record the
C3H8 concentration of the gas.
    (2) Select a CH4 span gas concentration that you use to
span your analyzers before emission testing. Use only span gases that
meet the specifications of Sec.  1065.750. Record the CH4
concentration of the gas.
    (3) Start and operate the FID analyzer according to the
manufacturer's instructions.
    (4) Confirm that the FID analyzer has been calibrated using
C3H8. Calibrate on a carbon number basis of one
(C1). For example, if you use a C3 H8
span gas of concentration 200 [mu]mol/mol, span the FID to respond with
a value of 600 [mu]mol/mol.

    (5) Zero the FID with a zero gas that you use for emission testing.
    (6) Span the FID with the C3H8 span gas that
you selected under paragraph (d)(1) of this section.
    (7) Introduce at the sample port of the FID analyzer, the
CH4 span gas that you selected under paragraph (d)(2) of
this section.
    (8) Allow time for the analyzer response to stabilize.
Stabilization time may include time to purge the analyzer and to
account for its response.
    (9) While the analyzer measures the CH4 concentration,
record 30 seconds of sampled data. Calculate the arithmetic mean of
these values.
    (10) For analyzers with multiple ranges, you need to perform the
procedure in this paragraph (d) only on a single range.
    (11) Divide the mean measured concentration by the recorded span
concentration of the CH4 calibration gas. The result is the
FID analyzer's response factor for CH4, RF
CH4[THC-FID].
    (e) THC FID CH4 response verification. This procedure is
only for FID analyzers that measure THC. Verify
RFCH4[THC-FID] as follows:
    (1) Perform a CH4 response factor determination as
described in paragraph (d) of this section. If the resulting value of
RFCH4[THC-FID] is within 5% of its most recent
previously determined value, the THC FID passes the CH4
response verification. For example, if the most recent previous value
for 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 RFCH4[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 Sec.  1065.660.
    (5) For analyzers with multiple ranges, you need to perform the
procedure in this paragraph (e) only on a single range.
    280. Section 1065.362 is amended by adding paragraph (d)(15) to
read as follows:

Sec.  1065.362  Non-stoichiometric raw exhaust FID O[bdi2] interference
verification.

* * * * *
    (d) * *
    (15) For analyzers with multiple ranges, you need to perform the
procedure in this paragraph (d) only on a single range.
    281. Section 1065.365 is amended by revising paragraphs (a), (b),
(d)(1), (e)(1), (f) introductory text, and (f)(1) to read as follows:

Sec.  1065.365  Nonmethane cutter penetration fractions.

    (a) Scope and frequency. If you use a FID analyzer and a nonmethane
cutter (NMC) to measure methane (CH4), determine the
nonmethane cutter's penetration fractions of CH4,
PFCH4, and ethane, PFC2H6. As detailed in this
section, these penetration fractions may be determined as a combination
of NMC penetration fractions and FID analyzer response factors,
depending on your particular NMC and FID analyzer configuration.
Perform this verification after installing the nonmethane cutter.
Repeat this verification within 185 days of testing to verify that the
catalytic activity of the cutter has not deteriorated. Note that
because nonmethane cutters can deteriorate rapidly and without warning
if they are operated outside of certain ranges of gas concentrations
and outside of certain temperature ranges, good engineering judgment
may dictate that you determine a nonmethane cutter's penetration
fractions more frequently.
    (b) Measurement principles. A nonmethane cutter is a heated
catalyst that removes nonmethane hydrocarbons from an exhaust sample
stream before the FID analyzer measures the remaining hydrocarbon
concentration. An ideal nonmethane cutter would have a CH4
penetration fraction, PFCH4, of 1.000, and the penetration
fraction for all other nonmethane hydrocarbons would be 0.000, as
represented by PFC2H6. The emission calculations in Sec.
1065.660 use the measured values from this verification to account for
less than ideal NMC performance.
* * * * *
    (d) * * *
    (1) Select CH4 and C2H6 analytical
gas mixtures and ensure that both mixtures meet the specifications of
Sec.  1065.750. Select a CH4 concentration that you would
use for spanning the FID during emission testing and select a
C2H6 concentration that is typical of the peak
NMHC concentration expected at the hydrocarbon standard or equal to the
THC analyzer's span value. For CH4 analyzers with multiple
ranges, perform this procedure on the highest range used for emission
testing.
* * * * *
    (e) * * *
    (1) Select CH4 and C2H6 analytical
gas mixtures and ensure that both mixtures meet the specifications of
Sec.  1065.750. Select a CH4 concentration that you would
use for spanning the FID during emission testing and select a
C2H6 concentration that is typical of the peak
NMHC concentration expected at the hydrocarbon standard and the
C2H6 concentration typical of the peak total
hydrocarbon (THC) concentration expected at the hydrocarbon standard or
equal to the THC analyzer's span value. For CH4 analyzers
with multiple ranges, perform this procedure on the highest range used
for emission testing.
* * * * *
    (f) Procedure for a FID calibrated with CH4, bypassing
the NMC. If you use a FID with an NMC that is calibrated with
CH4, by bypassing the NMC, determine its combined ethane
(C2H6) response factor and penetration fraction,
RFPFC2H6[NMC-FID], as well as its CH4 penetration
fraction, PFCH4[NMC-FID], as follows:
    (1) Select CH4 and C2H6 analytical
gas mixtures and ensure that both mixtures meet the specifications of
Sec.  1065.750. Select a CH4 concentration that you would
use for spanning the FID during emission testing and select a
C2H6 concentration that is typical of the peak
NMHC concentration expected at the hydrocarbon standard or equal to the
THC analyzer's span value. For CH4 analyzers with multiple
ranges, perform this procedure on the highest range used for emission
testing.
* * * * *

0
282. A new Sec.  1065.369 is added to subpart D under the center header
``Hydrocarbon Measurements'' to read as follows:

Sec.  1065.369  H[bdi2]O, CO, and CO[bdi2] interference verification
for photoacoustic alcohol analyzers.

    (a) Scope and frequency. If you measure ethanol or methanol using a
photoacoustic analyzer, verify the amount of H2O, CO, and
CO2 interference after initial analyzer installation and
after major maintenance.
    (b) Measurement principles. H2O, CO, and CO2
can positively interfere with a

photoacoustic analyzer by causing a response similar to ethanol or
methanol. If the photoacoustic analyzer uses compensation algorithms
that utilize measurements of other gases to meet this interference
verification, simultaneously conduct these other measurements to test
the compensation algorithms during the analyzer interference
verification.
    (c) System requirements. Photoacoustic analyzers must have combined
interference that is within (0.0  0.5) [micro]mol/mol. We
strongly recommend a lower interference that is within (0.0  0.25) [micro]mol/mol.
    (d) Procedure. Perform the interference verification by following
the procedure in Sec.  1065.375(d), comparing the results to paragraph
(c) of this section.

0
283. Section 1065.370 is amended by revising paragraphs (d)(9) and
(e)(5) to read as follows:

Sec.  1065.370  CLD CO[bdi2] and H[bdi2]O quench verification.

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

0
284. Section 1065.375 is amended by revising paragraph (d) to read as
follows:

Sec.  1065.375  Interference verification for N[bdi2]O analyzers.

* * * * *
    (d) Procedure. Perform the interference verification as follows:
    (1) Start, operate, zero, and span the N2O analyzer as
you would before an emission test. If the sample is passed through a
dryer during emission testing, you may run this verification test with
the dryer if it meets the requirements of Sec.  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 Sec.  1065.750 through distilled H2O in a
sealed vessel. If the sample is not passed through a dryer during
emission testing, control the vessel temperature to generate an
H2O level at least as high as the maximum expected during
emission testing. If the sample is passed through a dryer during
emission testing, control the vessel temperature to generate an
H2O level at least as high as the level determined in Sec.
1065.145(e)(2) for that dryer. Use interference span gas concentrations
that are at least as high as the maximum expected during testing.
    (3) Introduce the humidified interference test gas into the sample
system. You may introduce it downstream of any sample dryer, if one is
used during testing.
    (4) If the sample is not passed through a dryer during this
verification test, measure the H2O mole fraction,
xH2O, of the humidified interference test gas as
close as possible to the inlet of the analyzer. For example, measure
dewpoint, Tdew, and absolute pressure, ptotal, to
calculate xH2O. Verify that the H2O
content meets the requirement in paragraph (d)(2) of this section. If
the sample is passed through a dryer during this verification test, you
must verify that the H2O content of the humidified test gas
downstream of the vessel meets the requirement in paragraph (d)(2) of
this section based on either direct measurement of the H2O
content (e.g., dewpoint and pressure) or an estimate based on the
vessel pressure and temperature. Use good engineering judgment to
estimate the H2O content. For example, you may use previous
direct measurements of H2O content to verify the vessel's
level of saturation.
    (5) If a sample dryer is not used in this verification test, use
good engineering judgment to prevent condensation in the transfer
lines, fittings, or valves from the point where
xH2O is measured to the analyzer. We recommend
that you design your system so that the wall temperatures in the
transfer lines, fittings, and valves from the point where
xH2O is measured to the analyzer are at least 5
[ordm]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) While the analyzer measures the sample's concentration, record
its output for 30 seconds. Calculate the arithmetic mean of this data.
When performed with all the gases simultaneously, this is the combined
interference.
    (8) The analyzer meets the interference verification if the result
of paragraph (d)(7) of this section meets the tolerance in paragraph
(c) of this section.
    (9) You may also run interference procedures separately for
individual interference gases. If the interference gas levels used are
higher than the maximum levels expected during testing, you may scale
down each observed interference value (the arithmetic mean of 30 second
data described in paragraph (d)(7) of this section) by multiplying the
observed interference by the ratio of the maximum expected
concentration value to the actual value used during this procedure. You
may run separate interference concentrations of H2O (down to
0.025 mol/mol H2O content) that are lower than the maximum
levels expected during testing, but you must scale up the observed
H2O interference by multiplying the observed interference by
the ratio of the maximum expected H2O concentration value to
the actual value used during this procedure. The sum of the scaled
interference values must meet the tolerance for combined interference
as specified in paragraph (c) of this section.

0
285. Section 1065.376 is amended by revising paragraphs (b),
(d)(2)(vi), and (d)(2)(viii) to read as follows:

Sec.  1065.376  Chiller NO[bdi2] penetration.

* * * * *
    (b) Measurement principles. A chiller removes H2O, which
can otherwise

interfere with a NOX measurement. However, liquid
H2O remaining in an improperly designed chiller can remove
NO2 from the sample. If a chiller is used without an
NO2-to-NO converter upstream, it could remove NO2
from the sample prior NOX measurement.
* * * * *
    (d) * * *
    (2) * * *
    (vi) Next saturate the sampling system by overflowing a dewpoint
generator's output, set at a dewpoint of 50 [deg]C, to the gas sampling
system's probe or overflow fitting. Sample the dewpoint generator's
output through the sampling system and chiller for at least 10 minutes
until the chiller is expected to be removing a constant rate of
H2O.
* * * * *
    (viii) Correct x NOXmeas to x NOXdry based
upon the residual H2O vapor that passed through the chiller
at the chiller's outlet temperature and pressure.
* * * * *

Subpart E--[Amended]

0
286. Section 1065.405 is revised to read as follows:

Sec.  1065.405  Test engine preparation and maintenance.

    This part 1065 describes how to test engines for a variety of
purposes, including certification testing, production-line testing, and
in-use testing. Depending on which type of testing is being conducted,
different preparation and maintenance requirements apply for the test
engine.
    (a) If you are testing an emission-data engine for certification,
make sure it is built to represent production engines, consistent with
paragraph (f) of this section. This includes governors that you
normally install on production engines. Production engines should also
be tested with their installed governors. If 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. See
paragraph (b) of this section for guidance on setting adjustable
parameters. If you do not install governors on production engines,
simulate a governor that is representative of a governor that others
will install on your production engines. In certain circumstances, you
may incorporate test cell components to simulate an in-use
configuration, consistent with good engineering judgment. For example,
Sec. Sec.  1065.122 and 1065.125 allow the use of test cell components
to represent engine cooling and intake air systems. The provisions in
Sec.  1065.110(e) also apply to emission-data engines for
certification.
    (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 Sec.  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.

0
287. Section 1065.410 is amended by revising paragraph (c) to read as
follows:

Sec.  1065.410  Maintenance limits for stabilized test engines.

* * * * *
    (c) If you inspect an engine, keep a record of the inspection and
update your application to document any changes that result. You may
use any kind of equipment, instrument, or tool to identify bad engine
components or perform maintenance if it is available at dealerships and
other service outlets.
* * * * *

Subpart F--[Amended]

0
288. Section 1065.501 is revised to read as follows:

Sec.  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. 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 Sec.  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.

0
289. Section 1065.510 is amended by revising paragraph (d)(5)(ii) to
read as follows:

Sec.  1065.510  Engine mapping.

* * * * *
    (d) * * *

    (5) * * *
    (ii) For any constant-speed engine, you may perform an engine map
with a continuous torque sweep by continuing to record the mean
feedback speed and torque at 1 Hz or more frequently. Use the
dynamometer to increase torque. Increase the reference torque at a
constant rate from no-load to the endpoint torque as defined in
paragraph (d)(5)(i) of this section. You may continue mapping at higher
torque setpoints. Unless the standard-setting part specifies otherwise,
target a torque sweep rate equal to the manufacturer-declared test
torque (or a torque derived from your published power level if the
declared test torque is not known) divided by 180 seconds. Stop
recording after you complete the sweep. Verify that the average torque
sweep rate over the entire map is within 7% of the target
torque sweep rate. Use linear interpolation to determine intermediate
values from this series of mean feedback speed and torque values. Use
this series of mean feedback speeds and torques to generate the power
map as described in paragraph (e) of this section.
* * * * *

0
290. Section 1065.512 is amended by revising paragraph (b)(5) to read
as follows:

Sec.  1065.512  Duty cycle generation.

* * * * *
    (b) * * *
    (5) Ramped-modal cycles. For ramped-modal cycles, generate
reference speed and torque values at 1 Hz and use this sequence of
points to run the cycle and validate it in the same manner as with a
transient cycle. During the transition between modes, linearly ramp the
denormalized reference speed and torque values between modes to
generate reference points at 1 Hz. Do not linearly ramp the normalized
reference torque values between modes and then denormalize them. Do not
linearly ramp normalized or denormalized reference power points. These
cases will produce nonlinear torque ramps in the denormalized reference
torques. If the speed and torque ramp runs through a point above the
engine's torque curve, continue to command the reference torques and
allow the operator demand to go to maximum. Note that you may omit
power and either torque or speed points from the cycle-validation
criteria under these conditions as specified in Sec.  1065.514.
* * * * *

0
291. A new Sec.  1065.516 is added to subpart F to read as follows:

Sec.  1065.516  Sample system decontamination and preconditioning.

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

0
292. A new Sec.  1065.518 is added to subpart F to read as follows:

Sec.  1065.518  Engine preconditioning.

    (a) This section applies for engines where measured emissions are
affected by prior operation, such as with a diesel engine that relies
on urea-based selective catalytic reduction. Note that Sec.
1065.520(e) allows you to run practice duty cycles before the emission
test; this section recommends how to do this for the purpose of
preconditioning the engine. Follow the standard-setting part if it
specifies a different engine preconditioning procedure.
    (b) The intent of engine preconditioning is to manage the
representativeness of emissions and emission controls over the duty
cycle and to reduce bias.
    (c) This paragraph (c) specifies the engine preconditioning
procedures for different types of duty cycles. You must identify the
amount of preconditioning before starting to precondition. You must run
the predefined amount of preconditioning. You may measure emissions
during preconditioning. You may not abort an emission test sequence
based on emissions measured during preconditioning. For confirmatory
testing, you may ask us to run more preconditioning cycles than we
specify in this paragraph (c); we will agree to this only if you show
that additional preconditioning cycles are required to meet the intent
of paragraph (b) of this section, for example, due to the effect of DPF
regeneration on NH3 storage in the SCR catalyst. Perform
preconditioning as follows, noting that the specific cycles for
preconditioning are the same ones that apply for emission testing:

    (1) Cold-start transient cycle. Precondition the engine by running
at least one hot-start transient cycle. We will precondition your
engine by running two hot-start transient cycles. Immediately after
completing each preconditioning cycle, shut down the engine and
complete the engine-off soak period. Immediately after completing the
last preconditioning cycle, shut down the engine and begin the cold
soak as described in Sec.  1065.530(a)(1).
    (2) Hot-start transient cycle. Precondition the engine by running
at least one hot-start transient cycle. We will precondition your
engine by running two hot-start transient cycles. Immediately after
completing each preconditioning cycle, shut down the engine, then start
the next cycle (including the emission test) as soon as practical. For
any repeat cycles, start the next cycle within 60 seconds after
completing the last preconditioning cycle (this is optional for
manufacturer testing).
    (3) Hot-running transient cycle. Precondition the engine by running
at least one hot-running transient cycle. We will precondition your
engine by running two hot-running transient cycles. Do not shut down
the engine between cycles. Immediately after completing each
preconditioning cycle, start the next cycle (including the emission
test) as soon as practical. For any repeat cycles, start the next cycle
within 60 seconds after completing the last preconditioning cycle (this
is optional for manufacturer testing). See Sec.  1065.530(a)(1)(iii)
for additional instructions if the cycle begins and ends under
different operating conditions.
    (4) Discrete-mode cycle for steady-state testing. Precondition the
engine at the same operating condition as the next test mode, unless
the standard-setting part specifies otherwise. We will precondition
your engine by running it for at least five minutes before sampling.
    (5) Ramped-modal cycle for steady-state testing. Precondition the
engine by running at least the second half of the ramped-modal cycle,
based on the number of test modes. For example, for the five-mode cycle
specified in 40 CFR 1039.505(b)(1), the second half of the cycle
consists of modes three through five. We will precondition your engine
by running one complete ramped-modal cycle. Do not shut down the engine
between cycles. Immediately after completing each preconditioning
cycle, start the next cycle (including the emission test) as soon as
practical. For any repeat cycles, start the next cycle within 60
seconds after completing the last preconditioning cycle. See Sec.
1065.530(a)(1)(iii) for additional instructions if the cycle begins and
ends under different operating conditions.
    (d) You may conduct calibrations or verifications on any idle
equipment or analyzers during engine preconditioning.

0
293. Section 1065.520 is revised to read as follows:

Sec.  1065.520  Pre-test verification procedures and pre-test data
collection.

    (a) For tests in which you measure PM emissions, follow the
procedures for PM sample preconditioning and tare weighing according to
Sec.  1065.590.
    (b) Unless the standard-setting part specifies different
tolerances, verify at some point before the test that ambient
conditions are within the tolerances specified in this paragraph (b).
For purposes of this paragraph (b), ``before the test'' means any time
from a point just prior to engine starting (excluding engine restarts)
to the point at which emission sampling begins.
    (1) Ambient temperature of (20 to 30) [deg]C. See Sec.  1065.530(j)
for circumstances under which ambient temperatures must remain within
this range during the test.
    (2) Atmospheric pressure of (80.000 to 103.325) kPa and within
5 kPa of the value recorded at the time of the last engine
map. You are not required to verify atmospheric pressure prior to a hot
start test interval for testing that also includes a cold start.
    (3) Dilution air conditions as specified in Sec.  1065.140, except
in cases where you preheat your CVS before a cold start test. We
recommend verifying dilution air conditions just prior to the start of
each test interval.
    (c) You may test engines at any intake-air humidity, and we may
test engines at any intake-air humidity.
    (d) Verify that auxiliary-work inputs and outputs are configured as
they were during engine mapping, as described in Sec.  1065.510(a).
    (e) You may perform a final calibration of the speed, torque, and
proportional-flow control systems, which may include performing
practice duty cycles (or portions of duty cycles). This may be done in
conjunction with the preconditioning in Sec.  1065.518.
    (f) Verify the amount of nonmethane hydrocarbon contamination in
the exhaust and background HC sampling systems within 8 hours before
the start of the first test interval of each duty-cycle sequence for
laboratory tests. You may verify the contamination of a background HC
sampling system by reading the last bag fill and purge using zero gas.
For any NMHC measurement system that involves separately measuring
CH4 and subtracting it from a THC measurement or for any
CH4 measurement system that uses an NMC, verify the amount
of THC contamination using only the THC analyzer response. There is no
need to operate any separate CH4 analyzer for this
verification; however, you may measure and correct for THC
contamination in the CH4 sample path for the cases where
NMHC is determined by subtracting CH4 from THC or, where
CH4 is determined, using an NMC as configured in Sec.
1065.365(d), (e), and (f); and using the calculations in Sec.
1065.660(b)(2). Perform this verification as follows:
    (1) Select the HC analyzer range for measuring the flow-weighted
mean concentration expected at the HC standard.
    (2) Zero the HC analyzer at the analyzer zero or sample port. Note
that FID zero and span balance gases may be any combination of purified
air or purified nitrogen that meets the specifications of Sec.
1065.750. We recommend FID analyzer zero and span gases that contain
approximately the flow-weighted mean concentration of O2
expected during testing.
    (3) Span the HC analyzer using span gas introduced at the analyzer
span or sample port. Span on a carbon number basis of one
(C1). For example, if you use a C3H8
span gas of concentration 200 [mu]mol/mol, span the FID to respond with
a value of 600 [mu]mol/mol.
    (4) Overflow zero gas at the HC probe inlet or into a tee near the
probe outlet.
    (5) Measure the THC concentration in the sampling and background
systems as follows:
    (i) For continuous sampling, record the mean THC concentration as
overflow zero gas flows.
    (ii) For batch sampling, fill the sample medium (e.g., bag) and
record its mean THC concentration.
    (iii) For the background system, record the mean THC concentration
of the last fill and purge.
    (6) Record this value as the initial THC concentration,
xTHC[THC-FID]init, and use it to correct measured values as
described in Sec.  1065.660.
    (7) You may correct the measured initial THC concentration for
drift as follows:
    (i) For batch and continuous HC analyzers, after determining the
initial THC concentration, flow zero gas to the analyzer zero or sample
port. When the analyzer reading is stable, record the mean analyzer
value.
    (ii) Flow span gas to the analyzer span or sample port. When the
analyzer reading is stable, record the mean analyzer value.
    (iii) Use mean analyzer values from paragraphs (f)(2), (f)(3),
(f)(7)(i), and

(f)(7)(ii) of this section to correct the initial THC concentration
recorded in paragraph (f)(6) of this section for drift, as described in
Sec.  1065.550.
    (8) If any of the xTHC[THC-FID]init values exceed the
greatest of the following values, determine the source of the
contamination and take corrective action, such as purging the system
during an additional preconditioning cycle or replacing contaminated
portions:
    (i) 2% of the flow-weighted mean concentration expected at the HC
(THC or NMHC) standard.
    (ii) 2% of the flow-weighted mean concentration of HC (THC or NMHC)
measured during testing.
    (iii) 2 [mu]mol/mol.
    (9) If corrective action does not resolve the deficiency, you may
request to use the contaminated system as an alternate procedure under
Sec.  1065.10.

0
294. Section 1065.526 is revised to read as follows:

Sec.  1065.526  Repeating of void modes or test intervals.

    (a) Test modes and test intervals can be voided because of
instrument malfunction, engine stalling, emissions exceeding instrument
ranges, and other unexpected deviations from the specified procedures.
This section specifies circumstances for which a test mode or test
interval can be repeated without repeating the entire test.
    (b) This section is intended to result in replicate test modes and
test intervals that are identical to what would have occurred if the
cause of the voiding had not occurred. It does not allow you to repeat
test modes or test intervals in any circumstances that would be
inconsistent with good engineering judgment. For example, the
procedures specified here for repeating a mode or interval may not
apply for certain engines that include hybrid energy storage features
or emission controls that involve physical or chemical storage of
pollutants. This section applies for circumstances in which emission
concentrations exceed the analyzer range only if it is due to operator
error or analyzer malfunction. It does not apply for circumstances in
which the emission concentrations exceed the range because they were
higher than expected.
    (c) If one of the modes of a discrete-mode duty cycle is voided
while running the duty cycle as provided in this section, you may void
the results for that individual mode and continue the duty cycle as
follows:
    (1) If the engine has stalled or been shut down, restart the
engine.
    (2) Use good engineering judgment to restart the duty cycle using
the appropriate steps in Sec.  1065.530(b).
    (3) Stabilize the engine by operating it at the mode at which the
duty cycle was interrupted and continue with the duty cycle as
specified in the standard-setting part.
    (d) If an individual mode of a discrete-mode duty cycle sequence is
voided after running the full duty cycle, you may void results for that
mode and repeat testing for that mode as follows:
    (1) Use good engineering judgment to restart the test sequence
using the appropriate steps in Sec.  1065.530(b).
    (2) Stabilize the engine by operating it at that mode.
    (3) Sample emissions over an appropriate test interval.
    (4) If you sampled gaseous and PM emissions over separate test
intervals for a voided mode, you must void both test intervals and
repeat sampling of both gaseous and PM emissions for that mode.
    (e) If a transient or ramped-modal cycle test interval is voided as
provided in this section, you may repeat the test interval as follows:
    (1) Use good engineering judgment to restart (as applicable) and
precondition the engine to the same condition as would apply for normal
testing. This may require you to complete the voided test interval. For
example, you may generally repeat a hot-start test of a heavy-duty
highway engine after completing the voided hot-start test and allowing
the engine to soak for 20 minutes.
    (2) Complete the remainder of the test according to the provisions
in this subpart.
    (f) Keep records from the voided test mode or test interval in the
same manner as required for unvoided tests.

0
295. Section 1065.530 is amended by revising paragraphs (a), (b), and
(c) to read as follows:

Sec.  1065.530  Emission test sequence.

    (a) Time the start of testing as follows:
    (1) Perform one of the following if you precondition the engine as
described in Sec.  1065.518:
    (i) For cold-start duty cycles, shut down the engine. Unless the
standard-setting part specifies that you may only perform a natural
engine cooldown, you may perform a forced engine cooldown. Use good
engineering judgment to set up systems to send cooling air across the
engine, to send cool oil through the engine lubrication system, to
remove heat from coolant through the engine cooling system, and to
remove heat from any exhaust aftertreatment systems. In the case of a
forced aftertreatment cooldown, good engineering judgment would
indicate that you not start flowing cooling air until the
aftertreatment system has cooled below its catalytic activation
temperature. For platinum-group metal catalysts, this temperature is
about 200 [deg]C. Once the aftertreatment system has naturally cooled
below its catalytic activation temperature, good engineering judgment
would indicate that you use clean air with a temperature of at least 15
[deg]C, and direct the air through the aftertreatment system in the
normal direction of exhaust flow. Do not use any cooling procedure that
results in unrepresentative emissions (see Sec.  1065.10(c)(1)). You
may start a cold-start duty cycle when the temperatures of an engine's
lubricant, coolant, and aftertreatment systems are all between (20 and
30) [deg]C.
    (ii) For hot-start emission measurements, shut down the engine
immediately after completing the last preconditioning cycle. For any
repeat cycles, start the hot-start transient emission test within 60
seconds after completing the last preconditioning cycle (this is
optional for manufacturer testing).
    (iii) For testing that involves hot-stabilized emission
measurements, such as any steady-state testing with a ramped-modal
cycle, start the hot-stabilized emission test within 60 seconds after
completing the last preconditioning cycle (the time between cycles is
optional for manufacturer testing). If the hot-stabilized cycle begins
and ends with different operating conditions, add a linear transition
period of 20 seconds between hot-stabilized cycles where you linearly
ramp the (denormalized) reference speed and torque values over the
transition period. See Sec.  1065.501(c)(2)(i) for discrete-mode
cycles.
    (2) If you do not precondition the engine as described in Sec.
1065.518, perform one of the following:
    (i) For cold-start duty cycles, prepare the engine according to
paragraph (a)(1)(i) of this section.
    (ii) For hot-start duty cycles, first operate the engine at any
speed above peak-torque speed and at (65 to 85) % of maximum mapped
power until either the engine coolant, block, or head absolute
temperature is within 2% of its mean value for at least 2
min or until the engine thermostat controls engine temperature. Shut
down the engine. Start the duty cycle within 20 min of engine shutdown.
    (iii) For testing that involves hot-stabilized emission
measurements, bring the engine either to warm idle or the first
operating point of the duty cycle.

Start the test within 10 min of achieving temperature stability.
Determine temperature stability either as the point at which the engine
coolant, block, or head absolute temperature is within 2%
of its mean value for at least 2 min, or as the point at which the
engine thermostat controls engine temperature.
    (b) Take the following steps before emission sampling begins:
    (1) For batch sampling, connect clean storage media, such as
evacuated bags or tare-weighed filters.
    (2) Start all measurement instruments according to the instrument
manufacturer's instructions and using good engineering judgment.
    (3) Start dilution systems, sample pumps, cooling fans, and the
data-collection system.
    (4) Pre-heat or pre-cool heat exchangers in the sampling system to
within their operating temperature tolerances for a test.
    (5) Allow heated or cooled components such as sample lines,
filters, chillers, and pumps to stabilize at their operating
temperatures.
    (6) Verify that there are no significant vacuum-side leaks
according to Sec.  1065.345.
    (7) Adjust the sample flow rates to desired levels, using bypass
flow, if desired.
    (8) Zero or re-zero any electronic integrating devices, before the
start of any test interval.
    (9) Select gas analyzer ranges. You may automatically or manually
switch gas analyzer ranges during a test only if switching is performed
by changing the span over which the digital resolution of the
instrument is applied. During a test you may not switch the gains of an
analyzer's analog operational amplifier(s).
    (10) Zero and span all continuous analyzers using NIST-traceable
gases that meet the specifications of Sec.  1065.750. Span FID
analyzers on a carbon number basis of one (1), C1. For
example, if you use a C3H8 span gas of
concentration 200 [mu]mol/mol, span the FID to respond with a value of
600 [mu]mol/mol. Span FID analyzers consistent with the determination
of their respective response factors, RF, and penetration fractions,
PF, according to Sec.  1065.365.
    (11) We recommend that you verify gas analyzer responses after
zeroing and spanning by sampling a calibration gas that has a
concentration near one-half of the span gas concentration. Based on the
results and good engineering judgment, you may decide whether or not to
re-zero, re-span, or re-calibrate a gas analyzer before starting a
test.
    (12) Drain any accumulated condensate from the intake air system
before starting a duty cycle, as described in Sec.  1065.125(e)(1). If
engine and aftertreatment preconditioning cycles are run before the
duty cycle, treat the preconditioning cycles and any associated soak
period as part of the duty cycle for the purpose of opening drains and
draining condensate. Note that you must close any intake air condensate
drains that are not representative of those normally open during in-use
operation.
    (c) Start and run each test interval as described in this paragraph
(c). The procedure varies depending on whether the test interval is
part of a discrete-mode cycle, and whether the test interval includes
engine starting. Note that the standard-setting part may apply
different requirements for running test intervals. For example, 40 CFR
part 1033 specifies a different way to perform discrete-mode testing.
    (1) For steady-state discrete-mode duty cycles, start the duty
cycle with the engine warmed-up and running as described in Sec.
1065.501(c)(2)(i). Run each mode in the sequence specified in the
standard-setting part. This will require controlling engine speed,
engine load, or other operator demand settings as specified in the
standard-setting part. Simultaneously start any electronic integrating
devices, continuous data recording, and batch sampling. We recommend
that you stabilize the engine for at least 5 minutes for each mode.
Once sampling begins, sample continuously for at least 1 minute. Note
that longer sample times may be needed for accurately measuring very
low emission levels.
    (2) For transient and steady-state ramped-modal duty cycles that do
not include engine starting, start the test interval with the engine
running as soon as practical after completing engine preconditioning.
Simultaneously start any electronic integrating devices, continuous
data recording, batch sampling, and execution of the duty cycle.
    (3) If engine starting is part of the test interval, simultaneously
start any electronic integrating devices, continuous data recording,
and batch sampling before attempting to start the engine. Initiate the
sequence of points in the duty cycle when the engine starts.
    (4) For batch sampling systems, you may advance or delay the start
and end of sampling at the beginning and end of the test interval to
improve the accuracy of the batch sample, consistent with good
engineering judgment.
* * * * *
0
296. Section 1065.545 is revised to read as follows:

Sec.  1065.545  Verification of proportional flow control for batch
sampling.

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

both sample flow and total dilute exhaust (CVS) flow and demonstrate
that they always have the same inlet pressures and temperatures and
that they always operate under critical-flow conditions.

0
297. Section 1065.546 is amended by revising the section heading and
the introductory text to read as follows:

Sec.  1065.546  Verification of minimum dilution ratio for PM batch
sampling.

    Use continuous flows and/or tracer gas concentrations for transient
and ramped-modal cycles to verify the minimum dilution ratios for PM
batch sampling as specified in Sec.  1065.140(e)(2) over the test
interval. You may use mode-average values instead of continuous
measurements for discrete mode steady-state duty cycles. Determine the
minimum primary and minimum overall dilution ratios using one of the
following methods (you may use a different method for each stage of
dilution):
* * * * *

0
298. Section 1065.550 is revised to read as follows:

Sec.  1065.550  Gas analyzer range verification and drift verification.

    (a) Range verification. If an analyzer operated above 100% of its
range at any time during the test, perform the following steps:
    (1) For batch sampling, re-analyze the sample using the lowest
analyzer range that results in a maximum instrument response below
100%. Report the result from the lowest range from which the analyzer
operates below 100% of its range.
    (2) For continuous sampling, repeat the entire test using the next
higher analyzer range. If the analyzer again operates above 100% of its
range, repeat the test using the next higher range. Continue to repeat
the test until the analyzer always operates at less than 100% of its
range.
    (b) Drift verification. Gas analyzer drift verification is required
for all gaseous exhaust constituents for which an emission standard
applies. It is also required for CO2 even if there is no
CO2 emission standard. It is not required for other gaseous
exhaust constituents for which only a reporting requirement applies
(such as CH4 and N2O).
    (1) Verify drift using one of the following methods:
    (i) For regulated exhaust constituents determined from the mass of
a single component, perform drift verification based on the regulated
constituent. For example, when NOX mass is determined with a
dry sample measured with a CLD and the removed water is corrected based
on measured CO2, CO, THC, and NOX concentrations,
you must verify the calculated NOX value.
    (ii) For regulated exhaust constituents determined from the masses
of multiple subcomponents, perform the drift verification based on
either the regulated constituent or all the mass subcomponents. For
example, when NOX is measured with separate NO and
NO2 analyzers, you must verify either the NOX
value or both the NO and NO2 values.
    (iii) For regulated exhaust constituents determined from the
concentrations of multiple gaseous emission subcomponents prior to
performing mass calculations, perform drift verification on the
regulated constituent. You may not verify the concentration
subcomponents (e.g., THC and CH4 for NMHC) separately. For
example, for NMHC measurements, perform drift verification on NMHC; do
not verify THC and CH4 separately.
    (2) Drift verification requires two sets of emission calculations.
For each set of calculations, include all the constituents in the drift
verification. Calculate one set using the data before drift correction
and calculate the other set after correcting all the data for drift
according to Sec.  1065.672. Note that for purposes of drift
verification, you must leave unaltered any negative emission results
over a given test interval (i.e., do not set them to zero). These
unaltered results are used when verifying either test interval results
or composite brake-specific emissions over the entire duty cycle for
drift. For each constituent to be verified, both sets of calculations
must include the following:
    (i) Calculated mass (or mass rate) emission values over each test
interval.
    (ii) If you are verifying each test interval based on brake-
specific values, calculate brake-specific emission values over each
test interval.