40 CFR Appendix Table W-7 to Subpart W of Part 98 - Default Methane Emission Factors for Natural Gas Distribution

Natural gas distribution	Emission factor (scf/hour/ component)
Leaker Emission Factors - Transmission-Distribution Transfer Station 1 Components, Gas Service
Connector	1.69
Block Valve	0.557
Control Valve	9.34
Pressure Relief Valve	0.27
Orifice Meter	0.212
Regulator	0.772
Open-ended Line	26.131
Population Emission Factors - Below Grade Metering-Regulating station 1 Components, Gas Service 2
Below Grade M&R Station, Inlet Pressure >300 psig	1.30
Below Grade M&R Station, Inlet Pressure 100 to 300 psig	0.20
Below Grade M&R Station, Inlet Pressure <100 psig	0.10
Population Emission Factors - Distribution Mains, Gas Service 3
Unprotected Steel	12.58
Protected Steel	0.35
Plastic	1.13
Cast Iron	27.25
Population Emission Factors - Distribution Services, Gas Service 4
Unprotected Steel	0.19
Protected Steel	0.02
Plastic	0.001
Copper	0.03

1 Excluding customer meters.

2 Emission Factor is in units of “scf/hour/station.”

3 Emission Factor is in units of “scf/hour/mile.”

4 Emission Factor is in units of “scf/hour/number of services.”

[76 FR 80594, Dec. 23, 2011]