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Vents / Blowdowns / Relief

Venting Calculator

Converts a measured or engineered vented gas volume to pollutant mass using gas composition.

Input assumptions

Activity data
scf/hr
lb/lb-mol

From a representative gas analysis.

%

Weight percent of the selected pollutant (e.g. VOC, CH4) in the gas.

scf/lb-mol

Use the value for the standard temperature and pressure your program or method specifies.

hr/yr

8,760 hr/yr for potential to emit unless an enforceable limit applies.

%

Only claim control you can document and enforce.

Data source

Vent volume comes from metering, engineering calculations (vessel volume and pressure for blowdowns), or a measured rate. Document the basis and the gas analysis date.

Calculation result

Enter vented gas volume, gas molecular weight, pollutant weight fraction, … to see results, or fill demo values to explore.

Calculation methodology

Ideal-gas mass balance. Converts vented volume at standard conditions to moles with the molar volume, to mass with the gas molecular weight, then applies the pollutant's weight fraction from a gas analysis.

E (lb/hr) = V (scf/hr) ÷ MV (scf/lb-mol) × MW (lb/lb-mol) × w
Emission factor
None: mass balance from measured or engineered inputs.
Source / reference
Not provided. Results without a cited factor are not defensible.

Calculation set

Add several sources or pollutants and total them. Stored in this browser tab only until accounts launch.

No calculations added yet.

Native Excel and PDF exports with full methodology arrive with saved accounts. Phase 2

AirPermitHub provides educational, engineering, research, and compliance-support information. Information provided by the platform does not constitute legal advice and should not replace review of applicable regulations, permits, agency guidance, or consultation with qualified professionals. Full disclaimer