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Federal Register / Vol. 86, No. 122 / Tuesday, June 29, 2021 / Rules and Regulations 390. Amend 1066.835 by revising paragraphs a and f2 to read as follows:

1066.835 Exhaust emission test procedure for SC03 emissions.

a Drain and refill the vehicles fuel tanks if testing starts more than 72
hours after the most recent FTP or HFET
measurement with or without evaporative emission measurements.

f

2 Conditions before and after testing.
Use good engineering judgment to demonstrate that you meet the specified temperature and humidity tolerances in paragraph f1 of this section at all times before and between emission measurements.

391. Revise 1066.930 to read as follows:
1066.930 Equipment for point-source measurement of running losses.

34585

meeting the specifications in 40 CFR
86.10796i.
392. Amend 1066.1005 by revising paragraphs a, c, d, e, and f to read as follows:

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

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

For point-source measurement of running loss emissions, use equipment
lotter on DSK11XQN23PROD with RULES2

TABLE 1 OF 1066.1005SYMBOLS FOR QUANTITIES
Unit in terms of SI
base units
Symbol
Quantity
Unit
Unit symbol
a
A
A
ag
am
a0
a1
a

atomic hydrogen to carbon ratio
area
vehicle frictional load
acceleration of Earths gravity
calculated vehicle frictional load
intercept of least squares regression.
slope of least squares regression.
acceleration

mole per mole
square meter
pound force or newton
meters per second squared
pound force or newton

mol/mol
m2
lbf or N
m/s2
lbf or N

1.
m2.
mkgs2.
ms2.
mkgs2.

ft/s2 or m/s2

ms2.

B

lbf/mi/hr or Ns/m ..

kgs1.

b
b
c
C

vehicle load from drag and rolling resistance.
ratio of diameters
atomic oxygen to carbon ratio
conversion factor.
vehicle-specific aerodynamic effects

feet per second squared or meters per second squared.
pound force per mile per hour or newton second per meter.
meter per meter
mole per mole

m/m
mol/mol

1.
1.

lbf/mi/hr2 or Ns2/
m 2.

m1kg.

C

number of carbon atoms in a molecule

pound force per mile per hour squared or newton-second squared per meter squared.
C

number of carbon atoms in a molecule.

C.

Cd
CdA
Cf
Cp
Cv
d
D
D

discharge coefficient.
drag area
flow coefficient.
heat capacity at constant pressure
heat capacity at constant volume
diameter
distance
slope correlation

meter squared

m2

m2.

J/K
J/K
m
mi or m
lbf/mi/hr2 or Ns2/
m 2.

m2kgs2K1.
m2kgs2K1.
m.
m.
m2kg.

DF
e
F
n
FC
FR
g

dilution factor.
mass weighted emission result
force
frequency
angular speed shaft
friction compensation error
road-load force
ratio of specific heats

g/mi.
lbf or N
Hz
r/min
W
lbf or N
J/kgK/J/kgK

1.
kgs2.
s1.
30s1.
m2kgs3.
kgs2.
1.

H

ambient humidity

joule per kelvin
joule per kelvin
meters
miles or meters
pound force per mile per hour squared or newton second squared per meter squared.
grams/mile
pound force or newton
hertz
revolutions per minute
horsepower or watt
pound force or newton
joule per kilogram kelvin per joule per kilogram kelvin.
grams water vapor per kilogram dry air ..

Dh
I
I
i
IR
K
Kv
M
Me
m
N
n

change in height
inertia
current
indexing variable.
inertia work rating.
correction factor
calibration coefficient
viscosity, dynamic
molar mass
effective mass
mass
total number in series.
total number of pulses in a series.

meters
pound mass or kilogram
ampere

g H2O vapor/kg dry air.
m
lbm or kg
A

g H2O vapor/kg dry air.
m.
kg.
A.

pascal second
gram per mole
kilogram
pound mass or kilogram

m4sK0.5/kg
Pas
g/mol
kg
lbm or kg

1.
m4kg1sK0.5.
m1kgs1.
103kgmol1.
kg.
kg.

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