The procedures in this part generally follow the International System of Units (SI), as detailed in NIST Special Publication 811, which we incorporate by reference in Sec. 1065.1010. See Sec. 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: ----------------------------------------------------------------------------------------------------------------
Units in terms of
Symbol Quantity Unit Unit symbol SI base units----------------------------------------------------------------------------------------------------------------a............................... atomic hydrogen-to- mole per mole..... mol/mol........... 1
carbon ratio.A............................... area.............. square meter...... m\2\.............. m\2\a0.............................. intercept of least
squares
regression.a1.............................. slope of least
squares
regression.ag.............................. acceleration of meter per square m/s\2\............ m/s\2\
Earth's gravity. second.b............................... ratio of diameters meter per meter... m/m............... 1b............................... atomic oxygen-to- mole per mole..... mol/mol........... 1
carbon ratio.C.............................. number of carbon
atoms in a
molecule.Cd.............................. discharge
coefficient.Cf.............................. flow coefficient..d............................... atomic nitrogen-to- mole per mole..... mol/mol........... 1
carbon ratio.d............................... Diameter.......... meter............. m................. mDR.............................. dilution ratio.... mole per mole..... mol/mol........... 1e............................... error between a
quantity and its
reference.e............................... brake-specific gram per kilowatt g/(kW [middot] hr) g [middot] 3.6-1
emission or fuel hour. [middot] 10\6\
consumption. [middot] m-2
[middot] kg
[middot] s\2\F............................... F-test statistic..f............................... frequency......... hertz............. Hz................ s-1fn.............................. angular speed revolutions per r/min............. 2 [middot] [pi]
(shaft). minute. [middot] 60-1
[middot] m
[middot] m-1
[middot] s-1g............................... ratio of specific (joule per (J/(kg [middot] 1
heats. kilogram kelvin) K))/(J/(kg
per (joule per [middot] K)).
kilogram kelvin).g............................... atomic sulfur-to- mole per mole..... mol/mol........... 1
carbon ratio.K............................... correction factor. .................. .................. 1Kv.............................. calibration .................. m\4\ [middot] s m\4\ [middot] s
coefficient. [middot] K\0.5\/ [middot] K\0.5\
kg. [middot] kg-1l............................... length............ meter............. m................. mm............................... viscosity, dynamic pascal second..... Pa [middot] s..... m-1 [middot] kg
[middot] s-1M............................... molar mass\1\..... gram per mole..... g/mol............. 10-3 [middot] kg
[middot] mol-1m............................... mass.............. kilogram.......... kg................ kgm............................... mass rate......... kilogram per kg/s.............. kg [middot] s-1
second.n............................... viscosity, meter squared per m\2\/s............ m\2\ [middot] s-1
kinematic. second.N............................... total number in
series.n............................... amount of mole.............. mol............... mol
substance.n............................... amount of mole per second... mol/s............. mol [middot] s-1
substance rate.P............................... power............. kilowatt.......... kW................ 10\3\ [middot]
m\2\ [middot] kg
[middot] s-3PF.............................. penetration
fraction.p............................... pressure.......... pascal............ Pa................ m-1 [middot] kg
[middot] s-2r............................... mass density...... kilogram per cubic kg/m\3\........... kg [middot]
meter.Dp.............................. differential pascal............ Pa................ m-3m-1 [middot] kg
static pressure. [middot] s-2r............................... ratio of pressures pascal per pascal. Pa/Pa............. 1r\2\............................ coefficient of
determination.Ra.............................. average surface micrometer........ [micro]m.......... 10-6 m
roughness.Re............................. Reynolds number...RF.............................. response factor...RH.............................. relative humidity.s............................... non-biased
standard
deviation.
S............................... Sutherland kelvin............ K................. K
constant.SEE............................. standard estimate
of error.T............................... absolute kelvin............ K................. K
temperature.T............................... Celsius degree Celsius.... [deg]C............ K - 273.15
temperature.T............................... torque (moment of newton meter...... N [middot] m...... m\2\ [middot] kg
force). [middot] s-2u............................... plane angle....... degrees........... [deg]............. radt............................... time.............. second............ s................. sDt.............................. time interval, second............ s................. s
period, 1/
frequency.V............................... volume............ cubic meter....... m\3\.............. m\3\V............................... volume rate....... cubic meter per m\3\/s............ m\3\ [middot] s-1
second.W............................... work.............. kilowatt hour..... kW [middot] hr.... 3.6 [middot] 10-6
[middot] m\2\
[middot] kg
[middot] s-2wc.............................. carbon mass gram per gram..... g/g............... 1
fraction.x............................... amount of mole per mole..... mol/mol........... 1
substance mole
fraction \2\.x............................... flow-weighted mean mole per mole..... mol/mol........... 1
concentration.y............................... generic variable..Z............................... compressibility
factor.----------------------------------------------------------------------------------------------------------------\1\ See paragraph (f)(2) of this section for the values to use for molar masses. Note that in the cases of NOX
and HC, the regulations specify effective molar masses based on assumed speciation rather than actual
speciation.\2\ Note that mole fractions for THC, THCE, NMHC, NMHCE, and NOTHC are expressed on a C1 equivalent basis.
(b) Symbols for chemical species. This part uses the following symbols for chemical species and exhaust constituents: ------------------------------------------------------------------------
Symbol Species------------------------------------------------------------------------Ar................................ argon.C................................. carbon.CH2O.............................. formaldehyde.CH3OH............................. methanol.CH4............................... methane.C2H4O............................. acetaldehyde.C2H5OH............................ ethanol.C2H6.............................. ethane.C3H7OH............................ propanol.C3H8.............................. propane.C4H10............................. butane.C5H12............................. pentane.CO................................ carbon monoxide.CO2............................... carbon dioxide.H................................. atomic hydrogen.H2................................ molecular hydrogen.H2O............................... water.H2SO4............................. sulfuric acid.HC................................ hydrocarbon.He................................ helium.\85\Kr............................ krypton 85.N2................................ molecular nitrogen.NH3............................... ammonia.NMHC.............................. nonmethane hydrocarbon.NMHCE............................. nonmethane hydrocarbon equivalent.NO................................ nitric oxide.NO2............................... nitrogen dioxide.NOX............................... oxides of nitrogen.N2O............................... nitrous oxide.NMOG.............................. nonmethane organic gases.NONMHC............................ non-oxygenated nonmethane
hydrocarbon.NOTHC............................. non-oxygenated total hydrocarbon.O2................................ molecular oxygen.OHC............................... oxygenated hydrocarbon.\210\Po........................... polonium 210.PM................................ particulate matter.S................................. sulfur.SVOC.............................. semi-volatile organic compound.THC............................... total hydrocarbon.THCE.............................. total hydrocarbon equivalent.ZrO2.............................. zirconium dioxide.------------------------------------------------------------------------
(c) Prefixes. This part uses the following prefixes to define a quantity: ------------------------------------------------------------------------
Symbol Quantity Value------------------------------------------------------------------------[micro].............................. micro................... 10-6m.................................... milli................... 10-3c.................................... centi................... 10-2k.................................... kilo.................... 10\3\M.................................... mega.................... 10\6\------------------------------------------------------------------------
(d) Superscripts. This part uses the following superscripts to define a quantity: ------------------------------------------------------------------------
Superscript Quantity------------------------------------------------------------------------overbar (such as y)............... arithmetic mean.overdot (such as y)............... quantity per unit time.------------------------------------------------------------------------
(e) Subscripts. This part uses the following subscripts to define a quantity: ------------------------------------------------------------------------
Subscript Quantity------------------------------------------------------------------------abs............................... absolute quantity.act............................... actual condition.air............................... air, dry.amb............................... ambient.atmos............................. atmospheric.bkgnd............................. background.cal............................... calibration quantity.CFV............................... critical flow venturi.comb.............................. combined.composite......................... composite value.cor............................... corrected quantity.dil............................... dilution air.dew............................... dewpoint.
dexh.............................. diluted exhaust.dry............................... dry condition.dutycycle......................... duty cycle.exh............................... raw exhaust.exp............................... expected quantity.fn................................ feedback speed.frict............................. friction.fuel.............................. fuel consumption.hi, idle.......................... condition at high-idle.i................................. an individual of a series.idle.............................. condition at idle.in................................ quantity in.init.............................. initial quantity, typically before
an emission test.int............................... intake air.j................................. an individual of a series.mapped............................ conditions over which an engine can
operate.max............................... the maximum (i.e., peak) value
expected at the standard over a
test interval; not the maximum of
an instrument range.meas.............................. measured quantity.media............................. PM sample media.mix............................... mixture of diluted exhaust and air.norm.............................. normalized.out............................... quantity out.P................................. power.part.............................. partial quantity.PDP............................... positive-displacement pump.post.............................. after the test interval.pre............................... before the test interval.prod.............................. stoichiometric product.record............................ record rate.ref............................... reference quantity.rev............................... revolution.sat............................... saturated condition.s................................. slip.span.............................. span quantity.SSV............................... subsonic venturi.std............................... standard condition.stroke............................ engine strokes per power stroke.T................................. torque.test.............................. test quantity.test, alt......................... alternate test quantity.uncor............................. uncorrected quantity.vac............................... vacuum side of the sampling system.weight............................ calibration weight.zero.............................. zero quantity.------------------------------------------------------------------------
(f) Constants. (1) This part uses the following constants for the composition of dry air: ------------------------------------------------------------------------
Symbol Quantity mol/mol------------------------------------------------------------------------xArair...................... amount of argon in dry 0.00934
air.xCO2air..................... amount of carbon 0.000375
dioxide in dry air.xN2air...................... amount of nitrogen in 0.78084
dry air.xO2air...................... amount of oxygen in 0.209445
dry air.------------------------------------------------------------------------
(2) This part uses the following molar masses or effective molar masses of chemical species: ------------------------------------------------------------------------
g/mol (10-3
Symbol Quantity [middot] kg
[middot] mol-1)------------------------------------------------------------------------Mair........................ molar mass of dry air 28.96559
\1\.MAr......................... molar mass of argon... 39.948MC.......................... molar mass of carbon.. 12.0107MCH3OH...................... molar mass of methanol 32.04186MC2H5OH..................... molar mass of ethanol. 46.06844MC2H4O...................... molar mass of 44.05256
acetaldehyde.MC3H8....................... molar mass of propane. 44.09562MC3H7OH..................... molar mass of propanol 60.09502MCO......................... molar mass of carbon 28.0101
monoxide.MCH4........................ molar mass of methane. 16.0425MCO2........................ molar mass of carbon 44.0095
dioxide.MH.......................... molar mass of atomic 1.00794
hydrogen.MH2......................... molar mass of 2.01588
molecular hydrogen.MH2O........................ molar mass of water... 18.01528MCH2O....................... molar mass of 30.02598
formaldehyde.MHe......................... molar mass of helium.. 4.002602MN.......................... molar mass of atomic 14.0067
nitrogen.MN2......................... molar mass of 28.0134
molecular nitrogen.MNH3........................ molar mass of ammonia. 17.03052MNMHC....................... effective C1 molar 13.875389
mass of nonmethane
hydrocarbon \2\.MNMHCE...................... effective C1 molar 13.875389
mass of nonmethane
hydrocarbon
equivalent \2\.MNOX........................ effective molar mass 46.0055
of oxides of nitrogen
\3\.MN2O........................ molar mass of nitrous 44.0128
oxide.MO.......................... molar mass of atomic 15.9994
oxygen.MO2......................... molar mass of 31.9988
molecular oxygen.MS.......................... molar mass of sulfur.. 32.065MTHC........................ effective C1 molar 13.875389
mass of total
hydrocarbon \2\.MTHCE....................... effective C1 molar 13.875389
mass of total
hydrocarbon
equivalent \2\.------------------------------------------------------------------------\1\ See paragraph (f)(1) of this section for the composition of dry air.\2\ The effective molar masses of THC, THCE, NMHC, and NMHCE are defined
on a C1 basis and are based on an atomic hydrogen-to-carbon ratio, a,
of 1.85 (with [beta], [gamma], and [delta] equal to zero).\3\ The effective molar mass of NOX is defined by the molar mass of
nitrogen dioxide, NO2.
(3) This part uses the following molar gas constant for ideal gases: ------------------------------------------------------------------------
J/(mol [middot] K)
(m\2\ [middot] kg
Symbol Quantity [middot] s-2
[middot] mol-1
[middot] K-1)------------------------------------------------------------------------R........................... molar gas constant.... 8.314472------------------------------------------------------------------------
(4) This part uses the following ratios of specific heats for dilution air and diluted exhaust: ------------------------------------------------------------------------
[J/(kg [middot]
Symbol Quantity K)]/[J/(kg
[middot] K)]------------------------------------------------------------------------gair........................ ratio of specific 1.399
heats for intake air
or dilution air.gdil........................ ratio of specific 1.399
heats for diluted
exhaust.gexh........................ ratio of specific 1.385
heats for raw exhaust.------------------------------------------------------------------------
(g) Other acronyms and abbreviations. This part uses the following additional abbreviations and acronyms: ------------------------------------------------------------------------
------------------------------------------------------------------------ABS............................... acrylonitrile-butadiene-styrene.ASTM.............................. American Society for Testing and
Materials.BMD............................... bag mini-diluter.BSFC.............................. brake-specific fuel consumption.CARB.............................. California Air Resources Board.CFR............................... Code of Federal Regulations.CFV............................... critical-flow venturi.CI................................ compression-ignition.CITT.............................. Curb Idle Transmission Torque.CLD............................... chemiluminescent detector.CVS............................... constant-volume sampler.DF................................ deterioration factor.ECM............................... electronic control module.EFC............................... electronic flow control.e.g............................... for example.EGR............................... exhaust gas recirculation.EPA............................... Environmental Protection Agency.FEL............................... Family Emission Limit.FID............................... flame-ionization detector.FTIR.............................. Fourier transform infrared.GC................................ gas chromatograph.GC-ECD............................ gas chromatograph with an electron-
capture detector.GC-FID............................ gas chromatograph with a flame
ionization detector.HEPA.............................. high-efficiency particulate air.IBP............................... initial boiling point.IBR............................... incorporated by reference.i.e............................... in other words.ISO............................... International Organization for
Standardization.LPG............................... liquefied petroleum gas.MPD............................... magnetopneumatic detection.NDIR.............................. nondispersive infrared.NDUV.............................. nondispersive ultraviolet.NIST.............................. National Institute for Standards and
Technology.NMC............................... nonmethane cutter.PDP............................... positive-displacement pump.PEMS.............................. portable emission measurement
system.PFD............................... partial-flow dilution.PLOT.............................. porous layer open tubular.PMD............................... paramagnetic detection.PMP............................... Polymethylpentene.pt................................ a single point at the mean value
expected at the standard.psi............................... pounds per square inch.PTFE.............................. polytetrafluoroethylene (commonly
known as TeflonTM).RE................................ rounding error.RESS.............................. rechargeable energy storage system.RFPF.............................. response factor penetration
fraction.RMC............................... ramped-modal cycle.rms............................... root-mean square.RTD............................... resistive temperature detector.SAW............................... surface acoustic wave.SEE............................... standard estimate of error.SSV............................... subsonic venturi.SI................................ spark-ignition.THC-FID........................... total hydrocarbon flame ionization
detector.TINV.............................. inverse student t-test function in
Microsoft Excel.UCL............................... upper confidence limit.UFM............................... ultrasonic flow meter.U.S.C............................. United States Code.------------------------------------------------------------------------ [79 FR 23815, Apr. 28, 2014]