Methane & VOC Emissions from Controllers & Pumps
EPA default: 37.3 scf/hr per device (>6 scf/hr bleed rate)
EPA default: 1.39 scf/hr per device (<6 scf/hr bleed rate)
EPA default: 13.5 scf/hr average (includes actuation events)
EPA default: 70.4 scf/hr per pump
EPA default: 168.4 scf/hr per pump
OOOOa: After 2023, all new/modified controllers must be zero-emission or <6 scf/hr. Existing high-bleed controllers must be replaced per compliance schedule.
Understand pneumatic device types, EPA emission factors, OOOOa requirements, and reduction technologies
Pneumatic devices at oil and gas facilities use pressurized natural gas to operate control valves and pumps. When they actuate, they vent natural gas (primarily methane) to the atmosphere. EPA classifies these as high-bleed (>6 scf/hr, avg 37.3 scf/hr), low-bleed (<6 scf/hr, avg 1.39 scf/hr), and intermittent-vent (avg 13.5 scf/hr) controllers.
Under EPA NSPS OOOOa (finalized 2024), all new, modified, or reconstructed pneumatic controllers at oil and gas facilities must be zero-emission or emit less than 6 scf/hr. Existing high-bleed controllers must be replaced according to the compliance schedule. This effectively requires conversion to instrument air, electric, or low-bleed devices.
Methane emissions are calculated as: Device Count x Emission Factor (scf/hr) x Operating Hours/Year x Methane Fraction x Gas Density (0.0424 lb/scf). EPA provides default emission factors: 37.3 scf/hr for high-bleed, 1.39 scf/hr for low-bleed, and 13.5 scf/hr for intermittent-vent controllers. Results are converted to tons/year and metric tonnes for reporting.
Facilities emitting 25,000 metric tonnes of CO2-equivalent per year or more must report under 40 CFR Part 98 Subpart W. Pneumatic device emissions are converted to CO2e using the Global Warming Potential (GWP) for methane: 25 (AR4), 28 (AR5), or 80 (20-year horizon). A single continuous high-bleed controller (37.3 scf gas/hr, 8,760 hr/yr, ~85% methane) emits on the order of 130 MT CO2e/yr at GWP=25 (about 150 MT at the AR5 GWP=28) — so even a handful of such controllers is significant against the 25,000 MT threshold.