Regulations last checked for updates: Jan 31, 2025

Title 40 - Protection of Environment last revised: Nov 08, 2025
All TitlesTitle 40Chapter IPart 98Subpart WAppendix - Table W-1 to Subpart W of Part 98—Default Whole Gas Population Emission Factors
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Appendix - Table W-1 to Subpart W of Part 98—Default Whole Gas Population Emission Factors
Industry segment Source type/component Emission factor
(scf whole gas/
hour/unit)
Population Emission Factors—Pneumatic Device Vents and Pneumatic Pumps, Gas Service 1
• Onshore petroleum and natural gas productionContinuous Low Bleed Pneumatic Device Vents 26.8
• Onshore petroleum and natural gas gathering and boostingContinuous High Bleed Pneumatic Device Vents 221
Intermittent Bleed Pneumatic Device Vents 28.8
Pneumatic Pumps 313.3
• Onshore natural gas processingContinuous Low Bleed Pneumatic Device Vents 26.8
• Onshore natural gas transmission compressionContinuous High Bleed Pneumatic Device Vents 230
• Underground natural gas storageIntermittent Bleed Pneumatic Device Vents 22.3
• Natural gas distribution
Population Emission Factors—Major Equipment, Gas Service 1
• Onshore petroleum and natural gas productionWellhead8.87
• Onshore petroleum and natural gas gathering and boostingSeparator9.65
Meters/Piping7.04
Compressor13.8
Dehydrator8.09
Heater5.22
Storage Vessel1.83
Population Emission Factors—Major Equipment, Crude Service
Onshore petroleum and natural gas productionWellhead4.13
Separator4.77
Meters/Piping12.4
Compressor13.8
Dehydrator8.09
Heater3.2
Storage Vessel1.91
Population Emission Factors—Gathering Pipelines, by Material Type 4
Onshore petroleum and natural gas gathering and boostingProtected Steel0.93
Unprotected Steel8.2
Plastic/Composite0.28
Cast Iron8.4

1 For multi-phase flow that includes gas, use the gas service emission factors.

2 Emission factor is in units of “scf whole gas/hour/device.”

3 Emission factor is in units of “scf whole gas/hour/pump.”

4 Emission factors are in units of “scf whole gas/hour/mile of pipeline.”

[89 FR 42323, May 14, 2024]
authority: 42 U.S.C. 7401-7671q.
source: 74 FR 56374, Oct. 30, 2009, unless otherwise noted.
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