Pollutant PPMV Mass Concentration Emission Rate Calculator

The Pollutant ppmv, Mass Concentration and Emission Rate Calculator converts a gas-phase pollutant concentration between parts per million by volume and mass concentration, then multiplies the result by volumetric flow to give a mass emission rate. The conversion runs through the ideal-gas molar density, absolute pressure divided by the product of the molar gas constant and absolute temperature, and a molecular weight you enter.

It runs in either direction. Enter ppmv and it returns mass concentration; enter mass concentration and it returns ppmv. The inactive concentration field is hidden and takes no part in the calculation. It also reports the pollutant mole fraction, which is the ppmv divided by one million.

Two unit systems are offered. SI metric takes degrees Celsius, kPa absolute, cubic metres per minute and mg/m^3, and reports kg/h. US customary takes degrees Fahrenheit, psia, actual cubic feet per minute and lbm/MMft^3, and reports lbm/h. Internally every case is worked in kelvins, pascals, cubic metres, milligrams and kilograms.

The temperature and pressure it uses are the ones you type. There is no standard state anywhere in this calculator: it does not substitute a reference temperature or a reference pressure, and the flow it multiplies by is actual flow at that same state. There is no pollutant property table either, so the molecular weight is yours to supply and yours to be right about.

Purpose and model boundary

This model converts one gas pollutant between ppmv and mass concentration at an explicitly entered actual gas temperature and absolute pressure, then multiplies the matching-basis mass concentration by actual volumetric flow to calculate mass emission rate. It is an ideal-gas unit and basis conversion and supplies no emission factor or pollutant property lookup.

Inputs and units

Input basis is ppmv or mass concentration. The unit system is SI or U.S. customary. SI inputs use mg/m³, m³/min, °C, and kPa absolute; U.S. inputs use lbm/MMft³, acfm, °F, and psia. Pollutant molecular weight is a positive user input in g/mol. Flow is nonnegative and must describe the same actual wet/dry gas basis as the concentration.

Only the concentration field visible for the selected input basis participates. Temperature is converted to kelvin and pressure to pascals internally. Gauge pressure is not accepted.

Governing relationships

The workbook uses exact molar gas constant R = 8.31446261815324 J/(mol·K) and calculates gas molar density:

n/V = P / (R × T)

For entered ppmv:

x = ppmv / 1,000,000

C_mg/m3 = x × MW_g/mol × (P/(R T)) × 1000

which is implemented equivalently as:

C_mg/m3 = (ppmv/1000) × MW × molar density

For entered mass concentration, the inverse is:

ppmv = C_mg/m3 / (MW × molar density) × 1000

Mass emission rate is:

E_kg/h = C_mg/m3 × Q_m3/min × 60 / 1,000,000

U.S. customary inputs and outputs are converted using exact foot and pound identities before and after the same internal SI equations.

Calculation sequence

1. Validate the unit system, input basis, visible concentration, positive molecular weight, temperature, absolute pressure, and nonnegative actual flow.
2. Convert °C or °F to kelvin, pressure to pascals, flow to m³/min, and any entered U.S. mass concentration to mg/m³.
3. Calculate ideal-gas molar density P/(RT).
4. Convert the visible input concentration to both ppmv and mg/m³.
5. Divide ppmv by one million to obtain mole fraction.
6. Multiply mass concentration by matching-basis flow and convert to kg/h or lbm/h.
7. Verify physical/numeric ranges, populate the concentration-ramp chart, and evaluate status.

Outputs and interpretation

Primary outputs are pollutant ppmv, mass concentration in the selected unit system, and mass emission rate. Mole fraction is supporting evidence. The chart is a seven-point linear ramp from zero to the calculated mass concentration; it illustrates scale and does not represent a time series, probability distribution, measurement trace, or regulatory limit.

The emission rate is valid only when concentration and actual flow describe the same gas state and wet/dry basis.

Validation and status logic

The workbook evaluates status in this order:

Zero flow takes precedence over zero concentration. The derived gate also requires ppmv from 0 through 1,000,000, mole fraction from 0 through 1, and nonnegative public concentration and emission outputs.

Assumptions and limitations

• The gas is ideal at the entered actual pressure and temperature; no compressibility factor is applied.
• Molecular weight is user-entered and is not checked against a pollutant identity.
• Concentration and flow must share one actual pressure, temperature, and wet/dry basis.
• No humidity conversion, chemical speciation, sampling correction, measurement uncertainty, emission factor, destruction efficiency, annualization, or limit comparison is included.
• ppmv is constrained to the physical mole-fraction interval from zero through one million ppmv.
• All shipped values are synthetic demonstrations.

Restrictions and non-computing states

Temperature must be strictly above -273.15 °C or -459.67 °F, absolute pressure and molecular weight must be positive, and flow must be nonnegative. The hidden concentration input is inert. A mass-concentration entry that would imply more than 1,000,000 ppmv fails the derived physical gate even though its visible scalar input is nonnegative.

Zero flow and zero concentration are valid computing states and return CHECK, not NOT VALID.

Errors and warnings

Input checking can reject unknown modes or numeric bounds before the workbook runs. Workbook NOT VALID distinguishes input-domain failures from derived numeric/physical failures. Workbook CHECK preserves calculated zeros for zero flow or concentration. A connection or calculation-service failure is not an emission result. OK does not establish regulatory compliance or measurement quality.

This calculator implements the ordinary textbook ideal-gas relation between volumetric and mass concentration, and the mass balance that turns a concentration and a flow into a rate. No pollutant property table, emission factor set or limit table is embedded. The molecular weight, the gas state and the flow are user inputs, and every shipped value is synthetic. The workbook cites these sources for the equations and constants it uses.

• United States Environmental Protection Agency, unit conversion guidance for gas concentrations, for the ideal-gas relation among ppmv, molecular weight, absolute temperature and pressure, and mass. https://www3.epa.gov/ceampubl/learn2model/part-two/onsite/ia_unit_conversion.html
• United States Environmental Protection Agency, protocol for equipment leak emission estimates, for the concentration and flow relation. https://www.epa.gov/sites/default/files/2020-09/documents/protocol_for_equipment_leak_emission_estimates.pdf
• National Institute of Standards and Technology, CODATA recommended values of the fundamental physical constants, for the molar gas constant. https://physics.nist.gov/cuu/pdf/all.pdf
• National Institute of Standards and Technology, Special Publication 811 Appendix B.8, for the exact foot, pound, pressure and temperature identities used in both unit systems. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8

Naming these sources records provenance. It is not endorsement, certification or approval by any agency. The temperature and pressure your work is stated at, the molecular weight, the averaging provisions, and any limit the result is compared against must come from the governing rule or permit and from the test method.