Link to an amendment published at 89 FR 29765, Apr. 22, 2024.
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 (incorporated by reference in § 1036.810). 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 chemical species. This part uses the following symbols for chemical species and exhaust constituents:
Table 1 to Paragraph (a) of § 1036.805—Symbols for Chemical Species and Exhaust Constituents
| Symbol
| Species
|
|---|
| C | carbon.
|
| CH4 | methane.
|
| CH4N2O | urea.
|
| CO | carbon monoxide.
|
| CO2 | carbon dioxide.
|
| H2O | water.
|
| HC | hydrocarbon.
|
| NMHC | nonmethane hydrocarbon.
|
| NMHCE | nonmethane hydrocarbon equivalent.
|
| NMNEHC | nonmethane nonethane hydrocarbon.
|
| NO | nitric oxide.
|
| NO2 | nitrogen dioxide.
|
| NOX | oxides of nitrogen.
|
| N2O | nitrous oxide.
|
| PM | particulate matter. |
(b) Symbols for quantities. This part uses the following symbols and units of measure for various quantities:
Table 2 to Paragraph (b) of § 1036.805—Symbols for Quantities
| Symbol
| Quantity
| Unit
| Unit symbol
| Unit in terms of SI base units
|
|---|
| α | atomic hydrogen-to-carbon ratio | mole per mole | mol/mol | 1
|
| Α | Area | square meter | m
2 | m
2
|
| β | atomic oxygen-to-carbon ratio | mole per mole | mol/mol | 1
|
| CdΑ | drag area | meter squared | m
2 | m
2
|
| Crr | coefficient of rolling resistance | newton per kilonewton | N/kN | 10−
3
|
| D | distance | miles or meters | mi or m | m
|
| e | efficiency
| | | |
| ∈ | Difference or error quantity
| | | |
| E | mass weighted emission result | grams/ton-mile | g/ton-mi | g/kg-km
|
| Eff | efficiency
| | | |
| Em | mass-specific net energy content | megajoules/kilogram | MJ/kg | m
2·s−
2
|
| fn | angular speed (shaft) | revolutions per minute | r/min | π·30·s−
1
|
| g | gravitational acceleration | meters per second squared | m/s
2 | m·s−
2
|
| i | indexing variable
| | | |
| ka | drive axle ratio | | | 1
|
| ktopgear | highest available transmission gear
| | | |
| m | Mass | pound mass or kilogram | lbm or kg | kg
|
| M | molar mass | gram per mole | g/mol | 10−
3·kg·mol−
1
|
| M | total number in a series
| | | |
| M | vehicle mass | kilogram | kg | kg
|
| Mrotating | inertial mass of rotating components | kilogram | kg | kg
|
| N | total number in a series
| | | |
| Q | total number in a series
| | | |
| P | Power | kilowatt | kW | 10
3·m
2·kg·s−
3
|
| ρ | mass density | kilogram per cubic meter | kg/m
3 | m−
3·kg
|
| r | tire radius | meter | m | m
|
| SEE | standard error of the estimate
| | | |
| σ | standard deviation
| | | |
| T | torque (moment of force) | newton meter | N·m | m
2·kg·s−
2
|
| t | Time | second | s | s
|
| Δt | time interval, period, 1/frequency | second | s | s
|
| UF | utility factor
| | | |
| v | Speed | miles per hour or meters per second | mi/hr or m/s | m·s−
1
|
| W | Work | kilowatt-hour | kW·hr | 3.6·m
2·kg·s−
1
|
| wC | carbon mass fraction | gram/gram | g/g | 1
|
| wCH4N2O | urea mass fraction | gram/gram | g/g | 1
|
| x | amount of substance mole fraction | mole per mole | mol/mol | 1
|
| xb | brake energy fraction
| | | |
| xbl | brake energy limit | | | |
(c) Superscripts. This part uses the following superscripts for modifying quantity symbols:
Table 3 to Paragraph (c) of § 1036.805—Superscripts
| Superscript
| Meaning
|
|---|
| overbar (such as y
) | arithmetic mean.
|
| overdot (such as y
) | quantity per unit time. |
(d) Subscripts. This part uses the following subscripts for modifying quantity symbols:
| Subscript
| Meaning
|
|---|
| 65 | 65 miles per hour.
|
| A | A speed.
|
| a | absolute (e.g., absolute difference or error).
|
| acc | accessory.
|
| app | approved.
|
| axle | axle.
|
| B | B speed.
|
| C | C speed.
|
| C | carbon mass.
|
| Ccombdry | carbon from fuel per mole of dry exhaust.
|
| CD | charge-depleting.
|
| CO2DEF | CO2 resulting from diesel exhaust fluid decomposition.
|
| comb | combustion.
|
| comp | composite.
|
| cor | corrected.
|
| CS | charge-sustaining.
|
| cycle | cycle.
|
| D | distance.
|
| D | D speed.
|
| DEF | diesel exhaust fluid.
|
| engine | engine.
|
| exh | raw exhaust.
|
| front | frontal.
|
| fuel | fuel.
|
| H2Oexhaustdry | H2O in exhaust per mole of exhaust.
|
| hi | high.
|
| i | an individual of a series.
|
| idle | idle.
|
| int | test interval.
|
| j | an individual of a series.
|
| k | an individual of a series.
|
| m | mass.
|
| max | maximum.
|
| mapped | mapped.
|
| meas | measured quantity.
|
| MY | model year.
|
| neg | negative.
|
| pos | positive.
|
| R | range.
|
| r | relative (e.g., relative difference or error).
|
| rate | rate (divided by time).
|
| rated | rated.
|
| record | record.
|
| ref | reference quantity.
|
| speed | speed.
|
| stall | stall.
|
| test | test.
|
| tire | tire.
|
| transient | transient.
|
| µ | vector.
|
| UF | utility factor.
|
| vehicle | vehicle. |
(e) Other acronyms and abbreviations. This part uses the following additional abbreviations and acronyms:
Table 5 to Paragraph (e) of § 1036.805—Other Acronyms and Abbreviations
| Acronym
| Meaning
|
|---|
| ABT | averaging, banking, and trading.
|
| AECD | auxiliary emission control device.
|
| ASTM | American Society for Testing and Materials.
|
| BTU | British thermal units.
|
| CD | charge-depleting.
|
| CFR | Code of Federal Regulations.
|
| CI | compression-ignition.
|
| COV | coefficient of variation.
|
| CS | charge-sustaining.
|
| DEF | diesel exhaust fluid.
|
| DF | deterioration factor.
|
| DOT | Department of Transportation.
|
| E85 | gasoline blend including nominally 85 percent denatured ethanol.
|
| ECM | Electronic Control Module.
|
| EGR | exhaust gas recirculation.
|
| EPA | Environmental Protection Agency.
|
| FCL | Family Certification Level.
|
| FEL | family emission limit.
|
| FTP | Federal Test Procedure.
|
| GEM | Greenhouse gas Emissions Model.
|
| g/hp·hr | grams per brake horsepower-hour.
|
| GPS | global positioning system.
|
| GVWR | gross vehicle weight rating.
|
| Heavy HDE | heavy heavy-duty engine (see § 1036.140).
|
| Heavy HDV | heavy heavy-duty vehicle (see 40 CFR 1037.140).
|
| Light HDE | light heavy-duty engine (see § 1036.140).
|
| Light HDV | light heavy-duty vehicle (see 40 CFR 1037.140).
|
| LLC | Low Load Cycle.
|
| LPG | liquefied petroleum gas.
|
| Medium HDE | medium heavy-duty engine (see § 1036.140).
|
| Medium HDV | medium heavy-duty vehicle (see 40 CFR 1037.140).
|
| NARA | National Archives and Records Administration.
|
| NHTSA | National Highway Traffic Safety Administration.
|
| NTE | not-to-exceed.
|
| PEMS | portable emission measurement system.
|
| RESS | rechargeable energy storage system.
|
| SCR | selective catalytic reduction.
|
| SEE | standard error of the estimate.
|
| SET | Supplemental Emission Test.
|
| Spark-ignition HDE | spark-ignition heavy-duty engine (see § 1036.140).
|
| SI | spark-ignition.
|
| UL | useful life.
|
| U.S | United States.
|
| U.S.C | United States Code. |
(f) Constants. This part uses the following constants:
| Symbol
| Quantity
| Value
|
|---|
| g | gravitational constant | 9.80665 m·s−
2.
|
| R | molar gas constant | 8.314472 J/(mol·K) (m
2·kg·s−
2·mol−
1·K−
1). |
(g) Prefixes. This part uses the following prefixes to define a quantity:
| Symbol
| Quantity
| Value
|
|---|
| µ | micro | 10−
6
|
| m | milli | 10−
3
|
| c | centi | 10−
2
|
| k | kilo | 10
3
|
| M | mega | 10
6 |