40 C.F.R. § 1066.610

Current through October 31, 2024
Section 1066.610 - Dilution air background correction
(a) Correct the emissions in a gaseous sample for background using the following equation:

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Where:

x[emission]dexh = measured emission concentration in dilute exhaust (after dry-to-wet correction, if applicable).

x[emission]bkgnd = measured emission concentration in the dilution air (after dry-to-wet correction, if applicable).

DF = dilution factor, as determined in paragraph (b) of this section.

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Where:

xCO2 = amount of CO2 measured in the sample over the test interval.

xNMHC = amount of C1-equivalent NMHC measured in the sample over the test interval.

xCH4 = amount of CH4 measured in the sample over the test interval.

xCO = amount of CO measured in the sample over the test interval.

[ALPHA] = atomic hydrogen-to-carbon ratio of the test fuel. You may measure [ALPHA] or use default values from Table 1 of 40 CFR 1065.655 .

[BETA] = atomic oxygen-to-carbon ratio of the test fuel. You may measure [BETA] or use default values from Table 1 of 40 CFR 1065.655 .

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(c) Determine the dilution factor, DF, over the test interval for partial-flow dilution sample systems using the following equation:

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Where:

Vdexhstd = total dilute exhaust volume sampled over the test interval, corrected to standard reference conditions.

Vexhstd = total exhaust volume sampled from the vehicle, corrected to standard reference conditions.

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(d) Determine the time-weighted dilution factor, DFw, over the duty cycle using the following equation:

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Where:

N = number of test intervals

i = test interval number

t = duration of the test interval

DF = dilution factor over the test interval

Example:

N = 3

DF1 = 14.40

t1 = 505 s

DF2 = 24.48

t2 = 867 s

DF3 = 17.28

t3 = 505 s

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40 C.F.R. §1066.610

79 FR 23823 , Apr. 28, 2014, as amended at 86 FR 34583 , June 29, 2021