40 CFR § 1066.615 - NOX intake-air humidity correction.
§ 1066.615 NOX intake-air humidity correction.
You may correct NOX emissions for intake-air humidity as described in this section if the standard-setting part allows it. See § 1066.605(c) for the proper sequence for applying the NOX intake-air humidity correction.
MH2O = molar mass of H2O.
pd = saturated vapor pressure at the ambient dry bulb temperature.
RH = relative humidity of ambient air
Mair = molar mass of air.
patmos = atmospheric pressure.
MH2O = 18.01528 g/mol
pd = 2.93 kPa
RH = 37.5% = 0.375
Mair = 28.96559 g/mol
patmos = 96.71 kPa
χNOx = measured NOX emission concentration in the sample, after dry-to-wet and background corrections.
Hs = humidity scale. Set = 1 for FTP, US06, LA-92, and HFET test cycles. Set = 0.8825 for the SC03 test cycle.
H = ambient humidity, as determined in paragraph (a)(1) of this section.
H = 7.14741 g H2O vapor/kg dry air time weighted over the FTP test cycle
χNOx = 1.21 ppm