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Title 40Chapter ISubchapter UPart 1066 → Subpart K

Title 40: Protection of Environment

Subpart K—Definitions and Other Reference Material

§1066.1001   Definitions.
§1066.1005   Symbols, abbreviations, acronyms, and units of measure.
§1066.1010   Incorporation by reference.

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§1066.1001   Definitions.

The definitions in this section apply to this part. The definitions apply to all subparts unless we note otherwise. Other terms have the meaning given in 40 CFR part 1065. The definitions follow:

Average means the arithmetic mean of a sample.

Bag 1 means relating to the first 505 seconds of the FTP cold-start test interval. Note that the term bag 1 may also apply to measurement of constituents that are not collected in a bag, such as PM and continuously measured THC.

Bag 2 means relating to the last 867 seconds of the FTP cold-start test interval.

Bag 3 means relating to the first 505 seconds of the FTP hot-start test interval.

Bag 4 means relating to the last 867 seconds of the FTP hot-start test interval, if run. Note that bag 2 is generally used in place of bag 4.

Base inertia means a value expressed in mass units to represent the rotational inertia of the rotating dynamometer components between the vehicle driving tires and the dynamometer torque-measuring device, as specified in §1066.250.

C1-equivalent means a convention of expressing HC concentrations based on the total number of carbon atoms present, such that the C1-equivalent of an HC concentration equals the concentration multiplied by the mean number of carbon atoms in each HC molecule. For example, the C1-equivalent of 10 ppm of propane (C3H8) is 30 ppm. C1-equivalent concentration values may be denoted as “ppmC” in the standard-setting part. Densities may also be expressed on a C1 basis. Note that calculating HC masses from concentrations and densities is only valid where they are each expressed on the same carbon basis.

Driving schedule means a series of vehicle speeds that a vehicle must follow during a test. Driving schedules are specified in the standard-setting part. A driving schedule may consist of multiple test intervals.

Duty cycle means a set of weighting factors and the corresponding test cycles, where the weighting factors are used to combine the results of multiple test intervals into a composite result.

FTP means one of the following:

(1) The test cycle consisting of one UDDS as specified in paragraph (a) of Appendix I of 40 CFR part 86, followed by a 10-minute soak with the engine off and repeat driving through the first 505 seconds of the UDDS. See §1066.801(c)(1).

(2) The entire test procedure for measuring exhaust and/or evaporative emissions as described in §1066.801(c).

Footprint has the meaning given in the standard-setting part.

HFET means the test cycle specified in Appendix I of 40 CFR part 600.

Hot LA-92 means the first 1435 seconds of the LA-92 driving schedule.

LA-92 means the test cycle specified in Appendix I, paragraph (c), of 40 CFR part 86.

Nonmethane organic gas (NMOG) means the combination of organic gases other than methane as calculated in §1066.635. Note that for this part, the organic gases are summed on a mass basis without any adjustment for photochemical reactivity.

Parts-per-million (ppm) means ppm on a molar basis. For hydrocarbon concentrations including HC, THC, NMHC, and NMOG, ppm means ppm on a C1-equivalent molar basis.

Road-load coefficients means sets of A, B, and C road-load force coefficients that are used in the dynamometer road-load simulation, where road-load force at speed v equals A + B · v + C · v2.

SC03 means the test cycle specified in Appendix I, paragraph (h), of 40 CFR part 86.

SFTP means the collection of test cycles as given in 1066.801(c)(2).

Standard reference conditions means the following:

(1) Standard pressure is 101.325 kPa.

(2) Standard temperature is 293.15 K.

Test interval means a period over which a vehicle's emission rates are determined separately. For many standards, compliance with the standard is based on a weighted average of the mass emissions from multiple test intervals. For example, the standard-setting part may specify a complete duty cycle as a cold-start test interval and a hot-start test interval. In cases where multiple test intervals occur over a duty cycle, the standard-setting part may specify additional calculations that weight and combine results to arrive at composite values for comparison against the applicable standards.

Test weight has the meaning given in §§1066.410(b) or 1066.805.

UDDS means the test cycle specified in Appendix I, paragraph (a), of 40 CFR part 86.

US06 means the test cycle specified in Appendix I, paragraph (g), of 40 CFR part 86.

Unloaded coastdown means a dynamometer coastdown run with the vehicle wheels removed from the roll surface.

We (us, our) means the Administrator of the Environmental Protection Agency and any authorized representatives.

[79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015]

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§1066.1005   Symbols, abbreviations, acronyms, and units of measure.

The procedures in this part generally follow either the International System of Units (SI) or the United States customary units, as detailed in NIST Special Publication 811, which we incorporate by reference in §1066.1010. See 40 CFR 1065.20 for specific provisions related to these conventions. This section summarizes the way we use symbols, units of measure, and other abbreviations.

(a) Symbols for quantities. This part uses the following symbols and units of measure for various quantities:

SymbolQuantityUnitUnit symbolUnit in terms of SI base units
αatomic hydrogen to carbon ratiomole per molemol/mol1.
Aareasquare meterm2m2.
Avehicle frictional loadpound force or newtonlbf or Nm·kg·s−2.
agacceleration of Earth's gravitymeters per second squaredm/s2m·s−2.
Amcalculated vehicle frictional loadpound force or newtonlbf or Nm·kg·s−2.
a0intercept of least squares regression
a1slope of least squares regression
aaccelerationfeet per second squared or meters per second squaredft/s2 or m/s2m·s−2.
Bvehicle load from drag and rolling resistancepound force per mile per hour or newton second per meterlbf/(mi/hr) or N·s/mkg·s−1.
βratio of diametersmeter per meterm/m1.
βatomic oxygen to carbon ratiomole per molemol/mol1.
cconversion factor
Cvehicle-specific aerodynamic effectspound force per mile per hour squared or newton-second squared per meter squaredlbf/(mi/hr)2 or N·s2/m2m−1·kg.
C#number of carbon atoms in a moleculeC#number of carbon atoms in a moleculeC#.
Cddischarge coefficient
CdAdrag areameter squaredm2m2.
Cfflow coefficient
Cpheat capacity at constant pressurejoule per kelvinJ/Km2·kg·s−2·K−1.
Cvheat capacity at constant volumejoule per kelvinJ/Km2·kg·s−2·K−1.
Ddistancemiles or metersmi or mm.
Dslope correlationpound force per mile per hour squared or newton second squared per meter squaredlbf/(mi/hr)2 or N·s2/m2m−2·kg.
DFdilution factor1.
emass weighted emission resultgrams/mileg/mi
Fforcepound force or newtonlbf or Nkg·s−2.
fnangular speed (shaft)revolutions per minuter/minπ·30·s−1.
FCfriction compensation errorhorsepower or wattWm2·kg·s−3.
FRroad-load forcepound force or newtonlbf or Nkg·s−2.
γratio of specific heats(joule per kilogram kelvin) per (joule per kilogram kelvin)(J/(kg·K))/(J/(kg·K))1.
Ηambient humiditygrams water vapor per kilogram dry airg H2O vapor/kg dry airg H2O vapor/kg dry air.
Δhchange in heightmetersmm.
Iinertiapound mass or kilogramlbm or kgkg.
iindexing variable
IRinertia work rating
Kcorrection factor1.
Kvcalibration coefficientm4·s·K0.5/kgm4·kg−1·s·K0.5.
μviscosity, dynamicpascal secondPa·sm−1·kg·s−1.
Mmolar massgram per moleg/mol10−3·kg·mol−1.
Meeffective masskilogramkgkg.
mmasspound mass or kilogramlbm or kgkg.
Ntotal number in series
ntotal number of pulses in a series
Δpdifferential static pressurepascalPam−1·kg·s−2.
pdsaturated vapor pressure at ambient dry bulb temperaturekilopascalkPam−1·kg·s−2.
PFpenetration fraction
ρmass densitykilogram per cubic meterkg/m3m−3·kg.
Rdynamometer roll revolutionsrevolutions per minuterpmπ·30−1·s−1.
rratio of pressurespascal per pascalPa/Pa1.
r2coefficient of determination
Re#Reynolds number
RFresponse factor
RHrelative humidity
SSutherland constantkelvinKK.
SEEstandard estimate of error
SGspecific gravity
Δsdistance traveled during measurement intervalmetersmm.
Tabsolute temperaturekelvinKK.
TCelsius temperaturedegree Celsius °CK−273.15.
Ttorque (moment of force)newton meterN·mm2·kg·s−2.
ttimehour or secondhr or ss.
Δttime interval, period, 1/frequencysecondss.
vspeedmiles per hour or meters per secondmi/hr or m/sm · s−1.
Vvolumecubic meterm3m3.
flow volume ratecubic feet per minute or cubic meter per secondft3min or ms3m3 · s1.
VPvolume percent
xconcentration of emission over a test intervalpart per millionppm
ygeneric variable
Zcompressibility factor

(b) Symbols for chemical species. This part uses the following symbols for chemical species and exhaust constituents:

COcarbon monoxide.
CO2carbon dioxide.
N2molecular nitrogen.
NMHCnonmethane hydrocarbon.
NMHCEnonmethane hydrocarbon equivalent.
NMOGnonmethane organic gas.
NOnitric oxide.
NO2nitrogen dioxide.
NOXoxides of nitrogen.
N2Onitrous oxide.
O2molecular oxygen.
OHCoxygenated hydrocarbon.
PMparticulate matter.
THCtotal hydrocarbon.
THCEtotal hydrocarbon equivalent.

(c) Superscripts. This part uses the following superscripts to define a quantity:

overbar (such as )arithmetic mean.
overdot (such as )quantity per unit time.

(d) Subscripts. This part uses the following subscripts to define a quantity:

absabsolute quantity.
AC17air conditioning 2017 test interval.
actactual or measured condition.
actintactual or measured condition over the speed interval.
airair, dry.
cscold stabilized.
ctcold transient.
cUDDScold-start UDDS.
dexhdilute exhaust quantity.
emissionemission specie.
exhraw exhaust quantity.
expexpected quantity.
flowflow measurement device type.
HFEThighway fuel economy test.
hshot stabilized.
hthot transient.
hUDDShot-start UDDS.
ian individual of a series.
IDdriven inertia.
initinitial quantity, typically before an emission test.
ITtarget inertia.
maxthe maximum (i.e. peak) value expected at the standard over a test interval; not the maximum of an instrument range.
measmeasured quantity.
mixdilute exhaust gas mixture.
PMparticulate matter.
refreference quantity.
rolldynamometer roll.
satsaturated condition.
SC03air conditioning driving schedule.
spanspan quantity.
sdasecondary dilution air.
stdstandard conditions.
testtest quantity.
uncoruncorrected quantity.
zerozero quantity.

(e) Other acronyms and abbreviations. This part uses the following additional abbreviations and acronyms:

A/Cair conditioning.
AC17air conditioning 2017 test interval.
ALVWadjusted loaded vehicle weight.
ASMEAmerican Society of Mechanical Engineers.
CFRCode of Federal Regulations.
CFVcritical-flow venturi.
CNGcompressed natural gas.
CVSconstant-volume sampler.
EPAEnvironmental Protection Agency.
ETWequivalent test weight.
EVelectric vehicle.
FIDflame-ionization detector.
FTPFederal test procedure.
GCgas chromatograph.
GEMgreenhouse gas emissions model.
GHGgreenhouse gas (including CO2, N2O, and CH4).
GPSglobal positioning system.
GVWRgross vehicle weight rating.
HEVhybrid electric vehicle, including plug-in hybrid electric vehicles.
HFEThighway fuel economy test.
HLDTheavy light-duty truck.
HPLChigh pressure liquid chromatography.
IBRincorporated by reference.
LA-92Los Angeles 1992 driving schedule.
MDPVmedium-duty passenger vehicle.
NISTNational Institute for Standards and Technology.
NMCnonmethane cutter.
PDPpositive-displacement pump.
PHEVplug-in hybrid electric vehicle.
PMparticulate matter.
RESSrechargeable energy storage system.
ppmparts per million.
SAESociety of Automotive Engineers.
SC03air conditioning driving schedule.
SEAselective enforcement audit.
SFTPsupplemental federal test procedure.
SIInternational System of Units.
SSVsubsonic venturi.
UDDSurban dynamometer driving schedule.
US06aggressive driving schedule.
U.S.C.United States Code.
WWVNIST radio station call sign.

(f) This part uses the following densities of chemical species:

SymbolQuantity1 2g/m3g/ft3
ρCH4density of methane666.90518.8847
ρCH3OHdensity of methanol1332.0237.7185
ρC2H5OHC1-equivalent density of ethanol957.55927.1151
ρC2H4OC1-equivalent density of acetaldehyde915.65825.9285
ρC3H8density of propane611.03517.3026
ρC3H7OHC1-equivalent density of propanol832.7423.5806
ρCOdensity of carbon monoxide1164.4132.9725
ρCO2density of carbon dioxide1829.5351.8064
ρHC-gaseffective density of hydrocarbon—gaseous fuel3(see 3)(see 3)
ρCH2Odensity of formaldehyde1248.2135.3455
ρHC-liqeffective density of hydrocarbon—liquid fuel4576.81616.3336
ρNMHC-gaseffective density of nonmethane hydrocarbon—gaseous fuel3(see 3)(see 3)
ρNMHC-liqeffective density of nonmethane hydrocarbon—liquid fuel4576.81616.3336
ρNMHCE-gaseffective density of nonmethane equivalent hydrocarbon—gaseous fuel3(see 3)(see 3)
ρNMHCE-liqeffective density of nonmethane equivalent hydrocarbon—liquid fuel4576.81616.3336
ρNOxeffective density of oxides of nitrogen51912.554.156
ρN2Odensity of nitrous oxide1829.6651.8103
ρTHC-liqeffective density of total hydrocarbon—liquid fuel4576.81616.3336
ρTHCE-liqeffective density of total equivalent hydrocarbon—liquid fuel4576.81616.3336

1Densities are given at 20 °C and 101.325 kPa.

2Densities for all hydrocarbon containing quantities are given in g/m3-carbon atom and g/ft3-carbon atom.

3The effective density for natural gas fuel and liquefied petroleum gas fuel are defined by an atomic hydrogen-to-carbon ratio, α, of the hydrocarbon components of the test fuel. ρHCgas = 41.57 · (12.011 + (α · 1.008)).

4The effective density for gasoline and diesel fuel are defined by an atomic hydrogen-to-carbon ratio, α, of 1.85.

5The effective density of NOX is defined by the molar mass of nitrogen dioxide, NO2.

(g) Constants. (1) This part uses the following constants for the composition of dry air:

xArairamount of argon in dry air0.00934
xCO2airamount of carbon dioxide in dry air0.000375
xN2airamount of nitrogen in dry air0.78084
xO2airamount of oxygen in dry air0.209445

(2) This part uses the following molar masses or effective molar masses of chemical species:

(10−3 · kg · mol−1)
Mairmolar mass of dry air128.96559
MH2Omolar mass of water18.01528

1See paragraph (g)(1) of this section for the composition of dry air.

(3) This part uses the following molar gas constant for ideal gases:

SymbolQuantityJ/(mol · K)
(m2 · kg · s−2 · mol−1 · K−1)
Rmolar gas constant8.314472

(h) Prefixes. This part uses the following prefixes to define a quantity:


[79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74215, Oct. 25, 2016]

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§1066.1010   Incorporation by reference.

(a) Certain material is incorporated by reference into this part with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that specified in this section, a document must be published in the Federal Register and the material must be available to the public. All approved material is available for inspection at U.S. EPA, Air and Radiation Docket and Information Center, 1301 Constitution Ave. NW., Room B102, EPA West Building, Washington, DC 20460, (202) 202-1744, and is available from the sources listed below. It is also available for inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to http://www.archives.gov/federal__register/code__of__federal__regulations/ibr__locations.html.

(b) SAE International material. The following standards are available from SAE International, 400 Commonwealth Dr., Warrendale, PA 15096-0001, (877) 606-7323 (U.S. and Canada) or (724) 776-4970 (outside the U.S. and Canada), or http://www.sae.org:

(1) SAE J1263, Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques, revised March 2010, IBR approved for §§1066.301(b), 1066.305(a), and 1066.310(b).

(2) SAE J1634, Battery Electric Vehicle Energy Consumption and Range Test Procedure, revised October 2012, IBR approved for §1066.501(a).

(3) SAE J1711, Recommended Practice for Measuring the Exhaust Emissions and Fuel Economy of Hybrid-Electric Vehicles, Including Plug-In Hybrid Vehicles, revised June 2010, IBR approved for §1066.501(a).

(4) SAE J2263, Road Load Measurement Using Onboard Anemometry and Coastdown Techniques, revised December 2008, IBR approved for §§1066.301(b), 1066.305, and 1066.310(b).

(5) SAE J2264, Chassis Dynamometer Simulation of Road Load Using Coastdown Techniques, revised January 2014, IBR approved for §1066.315.

(6) SAE J2711, Recommended Practice for Measuring Fuel Economy and Emissions of Hybrid-Electric and Conventional Heavy-Duty Vehicles, issued September 2002, IBR approved for §1066.501(a).

(7) SAE J2951, Drive Quality Evaluation for Chassis Dynamometer Testing, revised January 2014, IBR approved for §1066.425(j).

(c) National Institute of Standards and Technology material. The following documents are available from National Institute of Standards and Technology, 100 Bureau Drive, Stop 1070, Gaithersburg, MD 20899-1070, (301) 975-6478, or www.nist.gov:

(1) NIST Special Publication 811, 2008 Edition, Guide for the Use of the International System of Units (SI), Physics Laboratory, March 2008, IBR approved for §§1066.20(a) and 1066.1005.

(2) [Reserved]

[79 FR 23823, Apr. 28, 2014, as amended at 80 FR 9124, Feb. 19, 2015; 81 FR 74217, Oct. 25, 2016]

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