Mass Emissions

Mass Emissions (mass per time) are calculated based on measured concentration, molecular weight and volumetric flow:


  • lb/hr is mass emissions in pounds per hour
  • [conc]ppmV is measured concentration, measured in parts per million, volume
  • MW is molecular weight in pounds per pound-mole (lb/lb-mol)
  • VolFlow is Volumetric flow, measured in dry, standard cubic feet per minute (dscfm)
  • 60 signifies 60 minutes per hour
  • 385.4 is the number of cubic feet in a pound-mole of gas at standard temperature and pressure
  • mass_emmissions_02.jpg
  • lb/MMBtu is mass emissions, measured in pounds per million British Thermal Units
  • MMBtu/hr is the heat input to a system, measured in million British Thermal Units per hour

Oxygen-adjusted concentrations

are used to correct measured concentrations under in-situ air-diluted conditions to a reference oxygen concentration level:


  • [poll]@X%O2 is the concentration of a pollutant (poll), corrected to a reference concentration (X%) of oxygen
  • [poll]meas is the measured in-stack concentration of the pollutant
  • %O2(ref) is the reference oxygen concentration, to which the measured concentration will be corrected
  • %O2(meas) is the measured in-stack oxygen concentration

Dry-basis concentration

is what the in-situ measured concentration would be if the water vapor were removed from the gas volume sampled:


  • ppmVd is the dry-basis pollutant concentration (moisture removed from the sampled gas volume)
  • ppmVw is the wet-basis pollutant concentration (moisture included in the sampled gas volume)

Conversion Between Volume and Mass-Based Concentrations:



  • mg/m3 is the mass-per-volume concentration of a gas
  • ppmV is the volume-per-volume concentration of a gas
  • MW is the molecular weight of the species
  • 24.04 is the volume in liters, of one mole of gas at STP

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