Code of Federal Regulations (alpha)

CFR /  Title 40  /  Part 1065  /  Sec. 1065.1005 Symbols, abbreviations, acronyms, and units of measure.

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]