RULE 4311 FLARES (Adopted June 20, 2002; Amended June 15, 2006) 

1.0 Purpose 

The purpose of this rule is to limit the emissions of volatile organic compounds (VOC) and 

oxides of nitrogen (NOx) from the operation of flares. 

2.0 Applicability 

This rule is applicable to operations involving the use of flares. 

3.0 Definitions 

3.1 Air-Assisted Flare: a combustion device where forced air is injected to promote 

turbulence for mixing and to provide combustion air. 

3.2 Air Pollution Control Officer (APCO): as defined in Rule 1020 (Definitions). 

3.3 Air Resources Board (ARB or CARB): as defined in Rule 1020 (Definitions). 

3.4 Coanda Effect Flare: A flare in which the high pressure flare gas flows along a curved 

surface inspirating air into the gas to promote combustion. 

3.5 Emergency: any situation or a condition arising from a sudden and reasonably 

unforeseeable event beyond the control of the operator. An emergency situation 

requires immediate corrective action to restore safe operation. A planned flaring event 

shall not be considered as an emergency. 

3.6 Enclosed Flare: a flare composed of multiple gas burners that are grouped in an 

enclosure, and are staged to operate at a wide range of flow rates. 

3.7 Flare: a direct combustion device in which air and all combustible gases react at the 

burner with the objective of complete and instantaneous oxidation of the combustible 

gases. Flares are used either continuously or intermittently and are not equipped with 

devices for fuel-air mix control or for temperature control. 

3.8 Flare Gas: gas burned in a flare. 

3.9 Gaseous Fuel: any gases used as combustion fuel which include, but are not limited to, 

any natural, process, synthetic, landfill, sewage digester, or waste gases. Gaseous fuel 

includes produced gas, pilot gas and, when burned, purge gas. 

3.10 Non-Assisted Flare: a combustion device without any auxiliary provision for 

enhancing the mixing of air into its flame. This definition does not include those flares, 

that by design, provide excess air at the flare tip. 

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3.11 NOx: any nitrogen oxide compounds 

3.12 Open Flare: a vertically or horizontally oriented open pipe flare from which gases are 

released into the air before combustion is commenced. 

3.13 Planned Flaring: a flaring operation that constitutes a designed and planned process at 

a source, and which would have been reasonably foreseen ahead of its actual 

occurrence, or is scheduled to occur. The operation of a flare for the purpose of 

performing equipment maintenance provided it does not exceed 200 hours per calendar 

year, or during compliance source testing or visible emission inspections is not 

considered planned flaring. Planned flaring includes, but is not limited to, the 

following flaring activities: 

 

3.13.1 Oil or gas well tests, well related work, tests ordered by a regulatory agency. 

 3.13.2 Equipment depressurization for maintenance purposes. 

 3.13.3 Equipment start-up or shutdown. 

 

3.13.4 Flaring of gas at production sources where no gas handling, gas injection or gas 

transmission facilities exists. 

3.13.5 Flaring of off-specification gas (i.e. non PUC quality gas), unless the operator 

can demonstrate that the gas must be flared for engineering or safety reasons, 

e.g., under emergency. 

3.14 Public Utilities Commission (PUC) Quality Gas: any gaseous fuel, gas containing fuel 

where the sulfur content is no more than one-fourth (0.25) grain of hydrogen sulfide per 

one hundred (100) standard cubic feet and no more than five grains of total sulfur per 

one hundred (100) standard cubic feet. PUC quality gas shall also mean high methane 

(at least 80 % by volume) gas as specified in PUC's General Order 58-A. 

3.15 Purge Gas: Nitrogen, carbon dioxide, liquefied petroleum gas, or natural gas, any of 

which can be used to maintain a non-explosive mixture of gases in the flare header or 

provide sufficient exit velocity to prevent any regressive flame travel back into the flare 

header. 

3.16 Steam-Assisted Flare: a combustion device where steam is injected into the 

combustion zone to promote turbulence for the mixing of the combustion air before it is 

introduced to the flame. 

3.17 Total Organic Gases: all hydrocarbon compounds containing hydrogen and carbon 

with or without other chemical elements. 

3.18 U.S. EPA: the United States Environmental Protection Agency. 

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3.19 Volatile Organic Compound (VOC): as defined in Rule 1020 (Definitions). 

4.0 Exemptions 

4.1 Flares operated in municipal solid waste landfills subject to the requirements of 

Rule 4642 (Solid Waste Disposal Sites) are exempt from this rule. 

4.2 Flares that are subject to the requirements of 40 CFR 60 Subpart WWW 

(Standards of Performance for Municipal Waste Landfills), or Subpart Cc 

(Emission Guidelines and Compliance Times for Municipal Solid Waste 

Landfills) are exempt from this rule. 

4.3 Except for the recordkeeping requirements in Section 6.2.4, the requirements of 

this rule shall not apply to any stationary source that has the potential to emit, for 

all processes, less than ten (10.0) tons per year of VOC and less than ten (10.0) 

tons per year of NOx. 

5.0 Requirements 

The owner or operator of any source subject to this rule shall comply with the following 

requirements: 

5.1 Flares that are permitted to operate only during an emergency are not subject to the 

requirements of Sections 5.6 and 5.7. 

5.2 The flame shall be present at all times when combustible gases are vented through the 

flare. 

5.3 The outlet shall be equipped with an automatic ignition system, or, shall operate with a 

pilot flame present at all times when combustible gases are vented through the flare, 

except during purge periods for automatic-ignition equipped flares. 

5.4 Except for flares equipped with a flow-sensing ignition system, a heat sensing device 

such as a thermocouple, ultraviolet beam sensor, infrared sensor, or an equivalent 

device, capable of continuously detecting at least one pilot flame or the flare flame is 

present shall be installed and operated. 

5.5 Flares that use flow-sensing automatic ignition systems and which do not use a 

continuous flame pilot shall use purge gas for purging. 

5.6 Open flares (air-assisted, steam-assisted, or non-assisted) in which the flare gas 

pressure is less than 5 psig shall be operated in such a manner that meets the provisions 

of 40 CFR 60.18. The requirements of this section shall not apply to Coanda effect 

flares. 

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5.7 Ground-level enclosed flares shall meet the following emission standards: 

Type of Flare and Heat Release 

Rate in MMBtu/hr 

VOC (lb/MMBtu) NOx (lb/MMBtu) 

Without Steam-assist 

 <10 MMBtu 0.0051 0.0952 

 10-100 MMBtu 0.0027 0.1330 

 >100 MMBtu 0.0013 0.5240 

With Steam-assist 

All 0.14 as TOG 0.068 

6.0 Administrative Requirements 

 6.1 Compliance Determination 

6.1.1 Upon request the operator of flares that are subject to Section 5.6 shall make 

available to the APCO the compliance determination records that demonstrate 

compliance with the provisions of 40 CFR 60.18, (c)(3) through (c)(5). 

6.1.2 The operator of ground-level enclosed flares shall conduct source testing at 

least once every 12 months to demonstrate compliance with Section 5.7. The 

operator shall submit a copy of the testing protocol to the APCO at least 30 

days in advance of the scheduled testing. The operator shall submit the source 

test results not later than 45 days after completion of the source testing. 

6.2 Recordkeeping 

The following records shall be maintained, retained on-site for a minimum of five 

years, and made available to the APCO, ARB, and U.S. EPA upon request: 

 

6.2.1 Copy of the compliance determination conducted pursuant to Section 6.1.1. 

6.2.2 Copy of the source testing result conducted pursuant to Section 6.1.2. 

6.2.3 For flares used during an emergency, record of the duration of flare operation, 

amount of gas burned, and the nature of the emergency situation. 

6.2.4 Beginning January 1, 2007, facilities claiming an exemption pursuant to 

Section 4.3 shall record annual throughput, material usage, or other information 

necessary to demonstrate an exemption under that section. 

6.3 Test Methods 

The test methods listed below shall be used to demonstrate compliance with this rule. 

Alternate equivalent test methods may be used provided the test methods have been 

approved by the APCO and EPA. 

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6.3.1 VOC, measured and calculated as carbon, shall be determined by EPA Method 

25, except when the outlet concentration must be below 50 ppm in order to 

meet the standard, in which case Method 25a may be used, and analysis of 

halogenated exempt compounds shall be analyzed by EPA Method 18 or ARB 

Method 422 “Determination of Volatile organic Compounds in Emission from 

Stationary Sources”. The VOC concentration in ppmv shall be converted to 

pounds per million Btu (lb/MMBtu) by using the following equation: 

 VOC in lb/MMBtu = 

)%9.20()10135.1(

)/,()(

2

6

xx O

dscfFxdryppmv MMBtu

−

 

 Where: F = As determined by EPA Method 19 

6.3.2 NOx emissions in pounds per million BTU shall be determined by using EPA 

Method 19. 

 

 6.3.3 NOx and O2 concentrations shall be determined by using EPA Method 3A, 

EPA Method 7E, or ARB 100. 

7.0 Compliance Schedule 

7.1 Flares at facilities with a potential to emit more than 25 tons per year of VOC or NOx 

that are installed and in operation before June 20, 2002 shall be in compliance with this 

rule by December 20, 2003. 

7.2 Flares, at facilities with a potential to emit more than 25 tons per year of VOCs or NOx, 

that are installed or constructed on or after June 20, 2002, shall be in compliance with 

this rule upon initial operation and thereafter. 

7.3 Flares that are installed before June 15, 2006 at facilities, which have the potential to 

emit between 10 tons per year and 25 tons per year of VOC or NOX shall demonstrate 

compliance with this rule by January 1, 2008. 

7.4 Flares, at facilities with a potential to emit between 10 tons per year and 25 tons per 

year of VOC or NOx that are installed or constructed on or after June 15, 2006, shall be 

in compliance with this rule upon initial operation and thereafter. 

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