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Fugitive Emissions Calculator

EPA Equipment Leak Estimation & LDAR Compliance

Fugitive Emissions Estimator
Estimate fugitive VOC and methane emissions from equipment components using EPA average emission factors. Enter component counts by type and service to calculate total emissions, check regulatory thresholds, and evaluate LDAR program benefits per 40 CFR Part 98 Subpart W, EPA Method 21, and NSPS OOOOa.

Facility & Method

Gas Properties

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%
hr/yr
$/MCF

LDAR Program & GWP

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EPA AR4: 25 • AR5: 28 • AR6: 29.8

Valves

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Pump Seals

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Other Components

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Understanding Fugitive Emissions

What Are Fugitive Emissions?
Unintentional leaks of VOCs and methane from process equipment components including valves, pump seals, compressor seals, flanges, and open-ended lines. EPA estimates these account for 5-15% of total facility GHG emissions.
EPA Estimation Methods:
Average Emission Factor: Component count-based (simplest)
Screening Value: Based on measured ppm levels
Correlation Equation: ppm-to-mass relationship
Regulatory Framework:
40 CFR Part 98 Subpart W (GHG reporting), EPA Method 21 (leak detection), NSPS OOOOa (new source standards), Clean Air Act Title V (major source permitting), API 2517 (evaporative loss from tanks).

Formula

E = N x EF x t
E = Annual emissions (kg/yr)
N = Number of components
EF = Emission factor (kg/hr/component)
t = Operating hours/year
VOC = E x VOC fraction
CH4 = E x CH4 fraction

Standards & References

  • EPA 40 CFR Part 98 Subpart W
    Petroleum & Natural Gas Systems GHG Reporting
  • EPA Method 21
    Determination of VOC Leaks
  • NSPS OOOOa
    Standards for New O&G Sources
  • API 2517
    Evaporative Loss from External Floating-Roof Tanks
  • EPA-453/R-95-017
    Protocol for Equipment Leak Emission Estimates

Engineering Notes

  • Accuracy: EPA average factors are facility-level estimates; actual emissions vary by equipment age and condition
  • LDAR savings: Monthly programs typically reduce fugitive emissions by ~63% (EPA guidance)
  • Major source: 10 TPY single HAP or 25 TPY combined HAPs triggers MACT requirements
  • Title V: 100 TPY of any criteria pollutant requires Title V permit
  • Compressor seals: Highest per-component emission factor; upgrade to dry gas seals for 95%+ reduction
  • OOOOa: Applies to affected facilities at well sites and compressor stations constructed after Sept 18, 2015

Quick Reference — EPA Emission Factors

  • Valves (gas): 0.0268 kg/hr/component
  • Compressor seals: 0.228 kg/hr/component
  • PRVs (gas): 0.0448 kg/hr/component
  • Connectors: 0.00025 kg/hr/component
  • Pump seals (light): 0.0199 kg/hr/component
  • Open-ended lines: 0.0023 kg/hr/component