NOX = (NOXo)(Pr/Po)0.5 e19 (Ho-0.00633) (288 °K/Ta)1.53
Where:
NOX = emission concentration of NOX at 15 percent O2 and ISO standard ambient conditions, ppm by volume, dry basis,
NOXo = mean observed NOX concentration, ppm by volume, dry basis, at 15 percent O2,
Pr = reference combustor inlet absolute pressure at 101.3 kilopascals ambient pressure. Alternatively, you may use 760 mm Hg (29.92 in Hg),
Po = observed combustor inlet absolute pressure at test, mm Hg. Alternatively, you may use the barometric pressure for the date of the test,
Ho = observed humidity of ambient air, g H2O/g air,
e = transcendental constant, 2.718, and
Ta = ambient temperature, °K.
40 C.F.R. §60.335