# 40 CFR 92.132 - Calculations.

(a) Duty-cycle emissions. This section describes the calculation of duty-cycle emissions, in terms of grams per brake horsepower hour (g/bhp-hr). The calculation involves the weighted summing of the product of the throttle notch mass emission rates and dividing by the weighted sum of the brake horsepower. The final reported duty-cycle emission test results are calculated as follows:

(1)

(i) Eidc = (Σ(Mij)(Fj))/(Σ(BHPj)(Fj))

(ii) Table B132-1 follows:

Table B132-1 - Weighting Factors for Calculating Emission Rates

Throttle notch setting | Test mode | Locomotive not equipped with multiple idle notches | Locomotive equipped with multiple idle notches | ||
---|---|---|---|---|---|

Line-haul | Switch | Line-haul | Switch | ||

Low Idle | 1a | NA | NA | 0.190 | 0.299 |

Normal Idle | 1 | 0.380 | 0.598 | 0.190 | 0.299 |

Dynamic Brake | 2 | 0.125 | 0.000 | 0.125 | 0.000 |

Notch 1 | 3 | 0.065 | 0.124 | 0.065 | 0.124 |

Notch 2 | 4 | 0.065 | 0.123 | 0.065 | 0.123 |

Notch 3 | 5 | 0.052 | 0.058 | 0.052 | 0.058 |

Notch 4 | 6 | 0.044 | 0.036 | 0.044 | 0.036 |

Notch 5 | 7 | 0.038 | 0.036 | 0.038 | 0.036 |

Notch 6 | 8 | 0.039 | 0.015 | 0.039 | 0.015 |

Notch 7 | 9 | 0.030 | 0.002 | 0.030 | 0.002 |

Notch 8 | 10 | 0.162 | 0.008 | 0.162 | 0.008 |

(2) Example: For the line-haul cycle, for locomotives equipped with normal and low idle, and with dynamic brake, the brake-specific emission rate for HC would be calculated as:

(3) In each mode, brake horsepower output is the power that the engine delivers as output (normally at the flywheel), as defined in § 92.2.

(i) For locomotive testing (or engine testing using a locomotive alternator/generator instead of a dynamometer), brake horsepower is calculated as:

(ii) For engine dynamometer testing, brake horsepower is determined from the engine speed and torque.

(4) For locomotive equipped with features that shut the engine off after prolonged periods of idle, the measured mass emission rate Mi1 (and Mi1a as applicable) shall be multiplied by a factor equal to one minus the estimated fraction reduction in idling time that will result in use from the shutdown feature. Application of this adjustment is subject to the Administrator's approval.

(b) Throttle notch emissions. This paragraph (b) describes the calculation of throttle notch emissions for all operating modes, including: idle (normal and low, as applicable); dynamic brake; and traction power points. The throttle notch (operating mode) emission test results, final reported values and values used in paragraph (a)(1) of this section are calculated as follows:

(1) Brake specific emissions (Eij) in grams per brake horsepower-hour of each species i (i.e., HC, CO, NOX or PM and, if appropriate, THCE or NMHC) for each mode j:

(i) EHC mode = HC grams/BHP-hr = MHC mode/Measured BHP in mode.

(ii) ETHCE mode = THCE grams/BHP-hr = MTHCE mode/Measured BHP in mode.

(iii) ENMHC mode = NMHC grams/BHP-hr = MNMHC mode/Measured BHP in mode.

(iv) ECO mode = CO grams/BHP-hr = MCO mode/Measured BHP in mode.

(v) ENOx mode = NOX grams/BHP-hr = MNOx mode/Measured BHP in mode.

(vi) EPM mode = PM grams/BHP-hr = MPM mode/Measured BHP in mode.

(vii) EAL mode = Aldehydes grams/BHP-hr = MAL mode/Measured BHP in mode.

(vii) EAL mode = Aldehydes grams/BHP-hr = MAL mode/Measured BHP in mode.

(2) Mass Emissions - Raw exhaust measurements. For raw exhaust measurements mass emissions (grams per hour) of each species for each mode:

(i) General equations. (A) The mass emission rate, MX mode (g/hr), of each pollutant (HC, NOX. CO2, CO, CH4 CH3OH, CH3CH2OH, CH2O, CH3CH2O) for each operating mode for raw measurements is determined based on one of the following equations:

(B) All measured volumes and volumetric flow rates must be corrected to standard temperature and pressure prior to calculations.

(ii) The following abbreviations and equations apply to this paragraph (b)(2):

(iii) Calculation of individual pollutant masses. Calculations for mass emission are shown here in multiple forms. One set of equations is used when sample is analyzed dry (equations where the concentrations are expressed as DX), and the other set is used when the sample is analyzed wet (equations where the concentrations are expressed as WX). When samples are analyzed for some constituents dry and for some constituents wet, the wet concentrations must be converted to dry concentrations, and the equations for dry concentrations used. Also, the equations for HC, NMHC, CO, and NOX have multiple forms that are algebraically equivalent: An explicit form that requires intermediate calculation of Vm and DVol or WVol; and an implicit form that uses only the concentrations (e.g., DCO) and the mass flow rate of the fuel. For these calculations, either form may be used.

(A) Hydrocarbons and nonmethane hydrocarbons.

(1) Hydrocarbons. (i) For petroleum-fueled engines:

(ii) For alcohol-fueled engines:

(2) Nonmethane hydrocarbons:

(B) Carbon monoxide:

(C) Oxides of nitrogen:

(D) Methanol:

(E) Ethanol:

(F) Formaldehyde:

(1) If aldehydes are measured using impingers:

(2) If aldehydes are measured using cartridges:

(3) The following definitions apply to this paragraph (b)(2)(iii)(F):

(G) Acetaldehyde:

(1) If aldehydes are measured using impingers:

(2) If aldehydes are measured using cartridges:

(3) The following definitions apply to this paragraph (b)(2)(iii)(G):

(iv) Conversion of wet concentrations to dry concentrations. Wet concentrations are converted to dry concentrations using the following equation:

(A) Iterative calculation of conversion factor. The conversion factor KW is calculated from the fractional volume of water in the exhaust on a dry basis (DH2O = volume of water in exhaust/dry volume of exhaust). Precise calculation of the conversion factor KW must be done by iteration, since it requires the dry concentration of HC, but HC emissions are measured wet.

(1) The conversion factor is calculated by first assuming DHC = WHC to calculate DVol:

(2) This estimate is then used in the following equations to calculate DVolair, then DH2O, then KW, which allows DHC to be determined more accurately from WHC:

(3) The calculations are repeated using this estimate of DHC. If the new estimate for KW is not within one percent of the previous estimate, the iteration is repeated until the difference in KW between iterations is less than one percent.

(B) Alternate calculation of DH2O (approximation). The following approximation may be used for DH2O instead of the calculation in paragraph (b)(2)(iv)(A) of this section:

(3) Mass Emissions - Dilute exhaust measurements. For dilute exhaust measurements mass emissions (grams per hour) of each species for each mode:

(i) General equations. The mass emission rate, Mx mode (g/hr) of each pollutant (HC, NOX. CO2, CO, CH4 CH3OH, CH3CH2OH, CH2O, CH3CH2O) for each operating mode for bag measurements and diesel continuously heated sampling system measurements is determined from the following equation:

(ii) The following abbreviations and equations apply to paragraphs (b)(3)(i) through (b)(3)(iii)(J) of this section:

(A) DF = Dilution factor, which is the volumetric ratio of the dilution air to the raw exhaust sample for total dilution, calculated as:

(B) Vmix = Diluted exhaust volumetric flow rate in cubic feet per hour corrected to standard conditions (528°R, and 760 mm Hg).

(C) Vf = Fraction of the total raw exhaust that is diluted for analysis.

(iii) Calculation of individual pollutants.

(A) MHC mode = Hydrocarbon emissions, in grams per hour by mode, are calculated using the following equations:

(B) MNOx mode = Oxides of nitrogen emissions, in grams per hour by mode, are calculated using the following equations:

(C) MCO2 mode = Carbon dioxide emissions, in grams per hour by mode, are calculated using the following equations:

(D)(1) MCO mode = Carbon monoxide emissions, in grams per hour by mode, are calculated using the following equations:

(2) If a CO instrument that meets the criteria specified in 40 CFR part 1065, subpart C, is used without a sample dryer according to 40 CFR 1065.145, COem must be substituted directly for COe and COdm must be substituted directly for COd.

(E) MCH4 mode = Methane emissions corrected for background, in gram per hour by mode, are calculated using the following equations:

(F) MCH3OH mode = Methanol emissions corrected for background, in gram per hour by mode, are calculated using the following equations:

1 = first impinger.

2 = second impinger.

(G) MC2H5OH mode = Ethanol emissions corrected for background, in gram per hour by mode, are calculated using the following equations:

1 = first impinger.

2 = second impinger.

(H) MCH2O mode = Formaldehyde emissions corrected for background, in gram per hour by mode, are calculated using the following equations:

(I) MCH3CHO mode = Acetaldehyde emissions corrected for background, in grams per hour by mode, are calculated using the following equations:

(J) MNMHC mode = Nonmethane hydrocarbon emissions, in grams per hour by mode.

(4) Particulate exhaust emissions. The mass of particulate for a test mode determined from the following equations when a heat exchanger is used (i.e., no flow compensation), and when background filters are used to correct for background particulate levels:

(c) Humidity calculations.

(1) The following abbreviations (and units) apply to paragraph (b) of this section:

(2) The specific humidity on a dry basis of the intake air (H) is defined as:

(3) The partial pressure of water vapor may be determined using a dew point device. In that case:

(4) The percent of relative humidity (RH) is defined as:

(5) The water-vapor volume concentration on a dry basis of the engine intake air (Y) is defined as:

(d) NO X correction factor.

(1) NOX emission rates (MNOx mode) shall be adjusted to account for the effects of humidity and temperature by multiplying each emission rate by KNOx, which is calculated from the following equations:

(e) Other calculations. Calculations other than those specified in this section may be used with the advance approval of the Administrator.