(Adopted: 04/07/89; Amended: 02/01/91; Amended: 02/01/91; 

Amended: 07/19/91; Amended: 08/02/91; Amended: 12/04/92; 

Amended: 12/10/93; Amended: 04/11/97; Amended: mm/dd/yy)

AVAQMD Rule 431.1 431.1-1

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

RULE 431.1 

Sulfur Content Of of Gaseous Fuels 

(aA) General

(1) Purpose 

(a) The purpose of this rule is to reduce sulfur oxides (SOx) emissions from the 

burning of gaseous fuels in stationary equipment requiring a permit to operate by 

the South Coast Air Quality Management District (District)..

(2) Applicability

(a) The provisions of this rule shall apply to any burning, transferring, selling or the 

offering for sale of any gaseous fuels containing sulfur compounds in excess of 

16 parts per million by volume (ppmv), calculated as hydrogen sulfide (H2S), in 

stationary equipment requiring a Permit to Operate (PTO) by the Antelope 

Valley Air Quality Management District (District). [Derived from SCAQMD 

Rule 431.1(b)]

(B) Definitions 

(1) BURN means to “Air Pollution Control Officer” (APCO) – The person appointed to the 

position of Air Pollution Control Officer of the District pursuant to the provisions of 

California Health & Safety Code §40750, and his or her designee. [Derived from 

AVAQMD Rule 1301(G)]

(2) “Authority to Construct Permit” (ATC) – A District permit required pursuant to the

provisions of District Rule 201 which must be obtained prior to the building, erecting, 

installation, alteration or replacement of any Permit Unit. Such permit may act as a

temporary PTO pursuant to the provisions of District Rule 202. [Derived from 

AVAQMD Rule 1301(K)]

(3) Burn – To combust any gaseous fuel, whether for useful heat or by incineration without 

heat recovery, except for flaring of emergency vent gases. 
431.1-2 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(2) CONTINUOUS EMISSION MONITORING SYSTEM (CEMS) is a4) “California 

Air Resources Board” (CARB) – The California State Air Resources Board the powers 

and duties of which are described in Part 2 of Division 26 of the California Health & 

Safety Code (commencing with section 39500). [Derived from AVAQMD Rule 

1301(P)]

(5) Continuous Emission Monitoring System (CEMS) – A system of equipment that 

continuously measures and records all parameters necessary to directly determine 

concentrations and/or mass emissions of selected pollutants, and which meets all of the 

requirements of Attachment A, Section II. 

(3) CONTINUOUS FUEL GAS MONITORING SYSTEM6) Continuous Fuel Gas 

Monitoring System” (CFGMS) is a – A system of equipment that continuously 

measures and records total sulfur concentration in the gaseous fuel prior to burning, and 

which meets all the requirements of Attachment A, Section I. 

(4) DAILY AVERAGE is an7) “Continuous Monitor” – a CEMS or CFGMS. [Derived 

from SCAQMD Rule 431.1(c)(4)]

(8) Daily Average – An arithmetic mean of all the of a facility’s sulfur compounds readings 

within a calendar day obtained according to the guideline specified in Attachment A.

(5) EMERGENCY VENT GAS is any(9) “District” – The Antelope Valley Air 

Quality Management District, the geographical area of which is described in District 

Rule 103. [Derived from AVAQMD Rule 1301(X)]

(10) Emergency Vent Gas – Any gas released from a process unit as a result of any process 

upset or breakdown. 

(6) GASEOUS FUEL is any11) Gaseous Fuel – Any gaseous material which releases heat 

when burned including, but not limited to, any natural, refinery, field produced, process, 

synthetic, landfill, sewage digester, or waste gases with a gross heating value of 2670 

kilocalories per cubic meter (300 BTU per cubic foot) or higher, at standard conditions. 

(7) LANDFILL GAS is any12) Landfill Gas – Any gas derived through any biological 

process from the decomposition of organic waste buried within a waste disposal site. 

(8) MONTHLY WEIGHTED AVERAGE SULFUR CONTENT is the 13) Monthly 

Weighted Average Sulfur Content – The result of the summation of average daily sulfur 

contents of the fuel(s) consumed multiplied by the average daily consumption rates of 

the fuel(s) consumed in any month divided by the total gaseous fuel consumption rate 

for that month. 

(9) NATURAL GAS is a14) Natural Gas – A mixture of gaseous hydrocarbons, with at 

least 80 percent methane (by volume), and of pipeline quality, such as the gas sold or 
AVAQMD Rule 431.1 431.1-3

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

distributed by any utility company regulated by the California Public Utilities 

Commission. 

(10) RECLAIM SOx FACILITY is a facility that has been included in the RECLAIM 

(Regional Clean Air Incentives Market)15) “Permit to Operate” (PTO) – A District 

permit required pursuant to the provisions of District Rule 203 which must be obtained 

prior to operation of a Permit Unit. An ATC may function as a temporary PTO pursuant 

to the provisions of District Rule 202. [Derived from AVAQMD Rule 1301(BBB)]

[Deleted-SCAQMD legacy program in accordance with the requirements of Rule 2001 

"Applicability", and/or which has been issued a RECLAIM Facility Permit and is 

subject to the requirements of Rule 2011, "Requirements for Monitoring, 

Reporting,recinded from AVAQMD by its removal from AVAQMD Rules and 

Recordkeeping for Oxides of Sulfur (SOx) Emissions".

(11) REFINERY GAS is anyRegulations](16) Refinery Gas – Any combustible gaseous 

by-product generated from a petroleum refinery process unit operation, with a gross 

heating value of 2670 kilocalories per cubic meter (300 BTU per cubic foot) or higher, 

at standard conditions.

(12) SEWAGE DIGESTER GAS is any(17) Sewage Digester Gas – Any gas derived 

from anaerobic decomposition of organic sewage within its containment. 

(13) SMALL REFINER means any person owning or operating a facility in California that 

produces materials from processing of petroleum crude provided such facility:18)

 “South Coast Air Quality Management District” – The air quality district created 

pursuant to Division 26, Part 3, Chapter 5.5 of the California Health & Safety Code 

(commencing with §40400). [Derived from AVAQMD Rule 1124.]

(A) has and at(18) [Deleted-Consolidated all times had since January 1, 1978, a 

crude oil capacity of not more than 55,000 barrels per stream day; and

(B) has not been, at any time since September 1, 1988, owned or controlled by any 

refiner that at the same time owned or controlled refineries in California with a total 

combined crude oil capacity of more than 55,000 barrels per stream day; and

(C) has not been at any time since September 1, 1988, owned or controlled by any 

refiner that at the same time owned or controlled refineries in the United States with a 

total combined crude oil capacity of more than 137,500 barrels per stream day; and

(D) has received a two-year extension forrefinery gas due to expiration of extra

compliance with California Air Resources Board's Phase II Reformulated Gasoline 

Requirements.time]
431.1-4 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(14) STANDARD CONDITIONS is the(19) Standard Conditions – The atmospheric 

state where the temperature is 60o°F and barometric pressure is 14.7 pounds per square

inch absolute.

(15) STREAM DAY is any(20) Stream Day – Any day or part of a day when a facility or a 

process unit is in operation. 

(21) “United States Environmental Protection Agency” (USEPA) - The United States

Environmental Protection Agency, the Administrator of the USEPA and his or her

authorized representative. [Derived from AVAQMD Rule 1301(YYY)]

(c) Sulfur Content C) Requirements 

(1) Natural gas 

A person shall not sell or offer for sale for use in the jurisdiction covered 

by of the District natural gas containing sulfur compounds, calculated as H2S, in excess 

of 16 parts per million by volume (ppmv) calculated as hydrogen sulfide. 

[Deleted- Provision expired by its own terms](2) Small Refiners Refinery gas

Anytime prior to May 4, 1996, a small refiner shall not:

(A) sell any refinery gas containing sulfur compounds in excess of 80 ppmv 

calculated as hydrogen sulfide, or

(B) burn or discharge to any fuel gas system or vent gas disposal system, refinery gas 

containing sulfur compounds in excess of 800 ppmv calculated as hydrogen 

sulfide, unless sulfur compounds in the stack gases are reduced to a level below 

that which would be emitted when using a fuel which complies with the 

requirements of this paragraph.

For purposes of this paragraph, the 80 or 800 ppmv limit shall apply to any gaseous fuel 

vented from a process unit or, if applicable, as vented from a sulfur removal unit. On or 

after May 4, 1996, the applicable sulfur compounds content limit for small refiners 

refinery gas shall be as specified in paragraph (c)(3) of this rule.

(3) Other Gaseous Fuels 

On or after the applicable compliance dates specified in Table 1, aA person shall 

not burn in equipment requiring a PTO, purchase, transfer, sell or offer for sale for use 

in the jurisdiction of the District, any gaseous fuel containing sulfur compounds,

calculated as ppmv hydrogen sulfideasH2S, in excess of the concentration limits as 

measured over the averaging periods for various gaseous fuels as specified in Table 1.

[Derived from SCAQMD Rule 431.1(d]
AVAQMD Rule 431.1 431.1-5

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

TABLE 1

Fuel Type Sulfur Limits 

ppmv 

Averaging Periods Compliance Date On or 

After

Refinery Gas 40 4 hrs

 Small Refiners 40 4 hrs May 4, 1996

 Other Refiners 40 4 hrs May 4, 1994

Landfill Gas 150 Daily November 17, 1995

40 or Daily or July 1, 1997

40 and 200 Monthly and15-

minutes

July 1, 1997

Sewage Digester 

Gas

40 or250 Daily or November 17, 1995

Sewage Digester 

Gas

40 and 500or Monthly and 15-

minutesDaily or

November 17, 1995

Other Gases 40 and 500 4 hrsMonthly and

15-minutes

May 4, 1994

(A) Landfill gas and sewage digester gas

(i)

A 

person who 

complies through 

monthly averaging 

shall install and 

properly operate a 

continuous 

monitor that 

compliesOther 

Gases

40 4 hrs

[Deleted column with the requirements specified in subdivision (d) of this rule. Compliance 

shall be determined based on readings obtained from the approved 

CFGMS or as calculated from the approved CEMS reading.

(B) Optional Facility Compliance Plan ("OFCP")
431.1-6 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

A person may comply with paragraph (c)(3) by achieving equivalent sulfur 

oxides (SOx) emission reductions within the facility, provided that the applicant 

submits and complies with an Optional Facility Compliance Plan ("OFCP") 

which has been approved in writing by the Executive Officer or designee. The 

OFCP shall:

(i) Contain, at a minimum, all data, records, and other information necessary 

to determine eligibility for alternative emission control, including but not 

limited to:

(I) A list of equipment and a description of the equipment where the 

gaseous fuel is being produced and/or burned;

(II) Amount of fuel produced by and/or to be burned in each of the 

equipment listed above;

(III) The estimated emission of sulfur dioxide from each equipment; 

and

(IV) Historical and projected information on fuel usage;

(ii) Demonstrate that daily total SOx emissions under the OFCP from all 

sources within the facility regulated under Rule 431.1 would be less than or 

equal to SOx emissions that would have been emitted based on actual total SOx

emissions from each source, or the sulfur content limits of this rule, whichever 

results in lower SOx emissions. The total SOx emissions generated from the 

subject fuel shall be determined using a continuous emission monitoring system 

(CEMS) specified in subdivision (d). The total emissions may be determined by 

monitoring the sulfur dioxide emissions from at least 70 percent of the total fuel 

gas consumed as obtained from a totalizing meter, and calculating the total 

emissions using the CEMS data;

(iii) Demonstrate that the permit units subject to the specified rule emission 

limitations are inexpired compliance with all applicable District rules or 

are on an approved schedule of compliance; anddates]

(iv) Demonstrate that continuous monitoring requirements of SOx emissions 

specified in subdivision (d) of this rule are complied with.

(4) [“OFCP” provision eliminated because in its present form did not conform to USEPAs economic 

incentive program (EIP). There are currently no facilities in the District opting to use an OFCP as a

means to comply with the emission limits of Rule 431.1.] (3) Previously Exempt or Previously 

Compliant Facilities 

A person burning gaseous fuel containing sulfur compounds in excess of the 

limits specified in Table 1 and whose facility had been previously exempt from this rule 

pursuant to paragraph (g)(8subsection (G)(6); or any person who, without the use of any 

sulfur removal or control system, had been previously in compliance with the limits 

specified in Table 1, shall: 
AVAQMD Rule 431.1 431.1-7

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(A) submit(a) Submit for approval by the Executive Officer or 

designeeAPCO within 30 days from the time of exceedance or non-compliance, 

a plan to demonstrate compliance with the requirements of the rule; 

(B) submit(b) Submit to the Executive Officer or designeeAPCO an 

application for a fuel gas control system within six months of the time of 

exceedance of the exemption criteria specified in paragraph (g)(8subsection

(G)(6), or non-compliance with the limit; 

(C) demonstrate (c) Demonstrate compliance with the limit specified 

in Table 1 no later than eighteen (18) months after the time of exceedance, or by 

July 1, 1997, whichever is later; and 

(D) comply with paragraph (d)(3).

(d(d) Comply with subsections (D)(1)and (D)(2), or (D)(3).

(D) Monitoring Requirements 

(1) A person burning landfill gas or sewage digester gasExcept as provided in subsection 

(D)(3), a person burning gaseous fuels, other than exclusively natural gas, in stationary 

equipment requiring a permit to operatePTO by the District shall install andhave a

properly operate aoperating continuous fuel gas monitoring system (CFGMS) to 

determine the sulfur content, calculated as H2S, of the fuel gas prior to burning, or a 

continuous emission monitoring system (CEMS) to determine SOx emissions after 

burning. SuchAll continuous monitormonitors, require District approval, which shall 

be approved according tobased on the requirements as set forth specified in Attachment 

A. An alternative method that ensures adequate compliance with the daily total sulfur 

content limitation of paragraphs (c)(1), (2) and (3) of this rule may be used upon written 

approval by the Executive Officers of the District, the California Air Resources Board 

(CARB), and the Regional Administrator of the Environmental Protection Agency 

(EPA), Region IX, or their designees. At a minimum, the alternative method shall meet 

the specifications of Attachment A, Section III.

Prior to the final compliance date specified for landfill gas in Table 1, (a person burning 

landfill gas may comply with the monitoring requirements specified in this paragraph, if 

data regarding total sulfur content of the landfill gas is contained and submitted to the 

District in a Rule 1150.1 plan.

(2) A person burning gaseous fuels other than natural gas, landfill gas, or sewage digester 

gas in stationary equipment requiring a District permit to operate shall install and 

properly operate a the CFGMS to determine the total sulfur contentupstream of any 

mixing of the gaseous fuel prior to burning, or a CEMS to determine the sulfur oxides 
431.1-8 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(SOx) emissions after burning according to the applicable requirements set forth in 

Attachment A. A person shall not mix refinery gases with natural gas, propane or other 

fuels upstream of the monitoring device. 

(3)b) A person subject to (c)(4)subsection (C)(3) of this rule who burns gaseous fuels 

containing sulfur compounds in excess of the limits specified in Table 1, shall 

installcomply with subsections (D)(1) and properly operate a CFGMS to 

determine the sulfur content in the fuel gas prior to combustion, or CEMS to 

determine the sulfur oxide emissions after burning, within(D)(2) no later than

twelve months from after the date a Permit to Construct a sulfur removal system 

an ATC is issued. Such monitor shall be approved according to the 

requirements of Attachment A, or an alternative method may be used upon 

approval by the Executive Officers of the District and CARB, and the Regional 

Administrator of the EPA, Region IX, or their designeesfor a sulfur removal 

system or comply with subsection (D)(3). 

(4c) Compliance with the Table 1 sulfur limits shall be determined based on readings 

obtained from an approved Continuous Monitor.

[Moved to section (D)(1)] [Moved to section (D)(1)] [Moved to section (D)(1)](2) A 

person installing a continuous monitorContinuous Monitor shall submit to the District 

for approval, a quality assurance procedure as specified in USEPA 40 CFR Part 60, 

Appendix F, Procedure 1 for CEMS and, as applicable, for CFGMS. 

(Aa) The quality assurance procedure specified above shall be approved in writing by 

the Executive Officer or designee before submitted to the District for written 

approval by the APCO prior to the CFGMS or CEMS final certification. 

(Bb) Any CFGMS or CEMS deemed to be out of control, as specified in Attachment 

A, according to the facility quality assurance procedure approved by the 

Executive Officer or designeeAPCO shall be corrected within 72 hours, as 

demonstrated by meeting the performance specification for which it was deemed 

out of control. 

(i) The person operating the CFGMS or CEMS shall notify the Executive 

Officer or designeeAPCO by telephone or facsimile of any breakdown(s) 

of the monitoring systems if the duration of the breakdown is in excess 

of 60 minutes or if there are three (3) or more breakdowns in any one day 

within 24 hours of the occurrence of the breakdown which triggers 

notification. Such report shall identify the time, location, equipment 

involved, and contact person. 

(ii) The person shall keep a record of any breakdown of the monitors and 

shall maintain such record for at least two years, and make it available to 

the District staff upon request.
AVAQMD Rule 431.1 431.1-9

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(iii) The person who complies with the provisions of clauses (d)(4)(B)(i) and 

(iisubsection (D)(2)(b)(i) and subsection (E) (3) shall not be considered 

in violation of this rule for the 72 hour period of breakdown provided 

that the breakdown did not result from operator error, neglect or 

improper operation or maintenance procedures. 

(3) A person burning landfill gas or sewage digester gas, or who is subject to subsection 

(C)(3) of this rule may use an alternative monitoring method, in lieu of the requirements 

in subsections (D)(1) and (D)(2), that ensures compliance with the daily total sulfur 

content limitation as specified in Table 1. Alternative monitoring methods shall not be 

used unless first approved in writing by the APCO, the California Air Resources Board 

(CARB), and the Regional Administrator of the Environmental Protection Agency 

(EPA), Region IX, or their designees.

(a) At a minimum, the alternative monitoring method shall meet the guidelines of 

Attachment A, Section III.

(b) A person subject to subsection (C)(3) of this rule shall submit an alternative 

monitoring method for approval no later than 45 days after the date an ATC for a 

sulfur removal system is issued.

(c) All monitoring must comply with the approved alternative monitoring method.

(d) District personnel shall use the approved alternative monitoring method to 

determine compliance with the limits of this rule.

[Derived from SCAQMD Rule 431.1 (e)(1 through 3)] 

(E) Reporting and Recordkeeping Requirements 

(1) All records required by this rule shall be maintained at the facility for at least five (5) 

years, and be made available to District staff upon request.

(2) Except at electric utility generating facilities and refineries, a person burning gaseous 

fuel, other than exclusively natural gas, in stationary equipment requiring a District 

permit to operatePTO, shall submit to the Executive Officer or designeeAPCO annual 

reports of the monthly fuel consumption and the total sulfur content of the fuel 

consumed. SuchThe annual report shall be submitted no later than 60 days following 

the end of the reporting year, and shall consist of the amount of any gaseous fuel 

consumed monthly, the applicable hourly, daily or monthly average sulfur content as 

determined by the deviceContinuous Monitor or approved alternative monitoring 

method as specified in paragraph (dsubsections (D)(1), (dD)(2), or (dD)(3) of this rule, 

and total SOx emissions, calculated as SO2. 

(2)3) A person burning gaseous fuel in stationary equipment located at electric utility 

generating facilities or refineries shall submit to the Executive Officer or 

designeeAPCO monthly reports of the daily fuel consumption, the monthly weighted 
431.1-10 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

average sulfur content (except for natural gas), and the maximum four (4)-hour average 

sulfur content of the fuel consumed, as determined by the device specified in paragraph 

(dsubsection (D)(2) of this rule and the total SOx emissions, calculated as SO2. The 

report shall be submitted withinno later than 30 days following the end of the reporting 

month. 

(3) The information specified in paragraphs (e)(1) and (e)(2) shall be maintained at the 

facility for at least two years, and be made available to the District staff upon request.

(4) The person operating a continuous monitor shall keep records as specified in clause 

(D)(2)(b)(i) for monitor breakdown (s)

[Derived from SCAQMD Rule 431.1 (f)(1 through 4)] 

(F) Test Methods 

The following may be used by the Executive Officer or designeeAPCO to verify compliance 

with the provisions of this rule: 

(1) For determination of compliance with sulfur content requirements of subdivision 

(csection (C): 

(A(a) The reference method for determining the concentration of sulfur compounds in 

a gaseous fuel, calculated as hydrogen sulfide, shall be DistrictH2S, shall be South Coast 

Air Quality Management District (SCAQMD) Method 307-91 - Determination of Sulfur 

in a Gaseous Matrix, or any other method demonstrated by the applicant to be 

equivalent and approved in writing by the Executive Officers of the DistrictAPCO, the 

CARB, and the Regional Administrator of the EPA, Region IX, or their designees, or 

(B(b) Data obtained from a continuous monitor, which is required to be installed and 

properly operated according to subdivision (dsection (D) and as approved by the 

Executive Officer or designeeAPCO pursuant to the guidelinesrequirements specified in 

Attachment A. 

(2) The gross heating value of gaseous fuels shall be determined by ASTM Method D 3588-

91 or, if applicable, ASTM Method D 4891-89. 

(3) The methane content of gaseous fuels shall be determined by ASTM Method D 1945-

81. 
AVAQMD Rule 431.1 431.1-11

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(g(G) Exemptions 

Unless otherwise specified, and provided that the person seeking the exemption supplies proof 

and verification upon request of applicable criteria to the satisfaction of the Executive Officer 

or designeeAPCO, the provisions of this rule shall not apply to the following cases: 

(1) A person selling, for use in the jurisdiction of the District, any gaseous fuel not 

complying with paragraphs (c)subsections (C)(1) through (cand (C)(3) provided that: 

(Aa) The gaseous fuel is delivered directly to a sulfur removal unit which is in full 

operation and which reduces the sulfur content to the limits specified in 

paragraphs (csubsections (C)(1) through (cand (C)(3); and 

(Bb) The seller notifies the Executive Officer or designeeAPCO prior to any such sale 

of the quantity, heating value, and composition of the gaseous fuel to be sold; 

and 

(C)c) The buyer has an approved Permit to ConstructATC and/or OperatePTO for the 

sulfur removal unit that will be used to treat the purchased gas. 

(2) Gaseous fuels containing sulfur used in the production of sulfur or sulfur compounds. 

(3) Waste gases being burned provided that: 

(Aa) The gross heating value of such gases is less than 2670 kilocalories per cubic 

meter (300 British Thermal Units per cubic foot) at standard conditions; and 

(Bb) Any supplemental fuel used to burn such waste gases does not contain sulfur or 

sulfur compounds in excess of the amount specified in this rule. 

(4) Gases being burned from fluidized catalytic cracking unit (FCCU) regenerators subject 

to District [Deleted-Rule 1105 or and Regulation XX.rescinded]

(5) Gases vented during refinery turnaround pursuant to District [Deleted-Rule 1123 

or and Regulation XX.rescinded]

(64) Gases vented to a control system pursuant to District Rule1173.[Deleted-Rule 466 and 

1173 or Regulation XX.rescinded]

(75) Gases vented intermittently to fuel gas or waste disposal system from pressure control 

valves, sight glasses, compressor bottles, sampling systems, and pump and compressor 

case vents. 

(86) Any facility which emits less than five (5) pounds per day total sulfur compounds, 

calculated as hydrogen sulfideH2S, from the burning of gaseous fuels other than natural 

gas. Emissions of total sulfur compounds shall be measured based on fuel analysis, 

using the test method specified in paragraph (fsubsection (F)(1), and the maximum daily 
431.1-12 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

gaseous fuel consumption. This exemption shall not apply to the requirement of 

paragraph (csubsection (C)(1). 

(97) A person is exempt from the requirements of paragraph (dsubsection (D)(1) and (d)(2) if 

the person demonstrates to the satisfaction of the Executive Officer or designeeAPCO

that the supplier of the gaseous fuel has complied with the requirements of subdivision 

(dsection (D) for such fuel. 

(10) Until November 17, 1997, any gaseous fuel sold or purchased in a transaction between a 

RECLAIM SOx facility and a Non-RECLAIM SOx facility is exempt from the sulfur 

content requirements specified in paragraphs (c)(1), (2) and (3), provided that:

(A) both the buyer and seller of the gaseous fuel submit to the Executive Officer or 

designee monthly written report of the quantities and daily averages of the total 

sulfur contents of the gaseous fuel sold to the buyer or purchased from the seller. 

 The daily average of total sulfur contents of gaseous fuels shall be monitored 

and reported to the District in a manner and format specified by the Executive 

Officer or designee. Such report shall be submitted within 30 calendar days 

following the end of the reporting month; and

(B) the RECLAIM SOx facility reports to the District and includes all SOx emissions 

generated from the burning of such gaseous fuel, as part of the facility's total 

SOx emissions pursuant to Rule 2004.

(11() [Deleted-RECLAIM program recinded from District Rules and Regulations]

(8) On or after July 1, 1997, a person previously in compliance with the limits specified in 

Table 1 of this rule shall be exempt from the requirements of paragraph (csubsection

(C)(43) provided that: the alternative monitoring method pursuant to paragraph 

(dsection (D) yields no more than three individual readings in a calendar year in excess 

of the limits specified in Table 1; that no single reading exceeds a fuel sulfur limit of 50 

ppmby 25 percent; and that the sampling frequency is no longer than once per week.

[Derived from SCAQMD Rule 431.1(h)(11)]

See SIP Table at http://www.avaqmd.ca.gov/Modules/ShowDocument.aspx?documentid=921

[SIP: Submitted as amended 11/17/95 on 1/31/96; Submitted as amended 10/2/92 on 1/11/93; 

Submitted as amended 5/4/90 on 12/31/90; Approved 10/19/84, 49 FR 41028, 40 CFR 

52.220(c)(137)(vii)(B); Approved _______, ______, 40 CFR 52.220(c)(125)(ii)(A); approved 

9/28/81, 46 FR 47451, 40 CFR 52.220(c)(65)(ii)]
AVAQMD Rule 431.1 431.1-13

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

ATTACHMENT A 

SECTION I - 

REQUIREMENTS FOR CONTINUOUS 

FUEL GAS MONITORING SYSTEM (CFGMS) 

A continuous fuel gas monitor used for determining the sulfur content of any gaseous fuel shall: 

(1) Continuously monitor and record the concentration by volume (dry basis) of sulfur compounds 

in ppmv as H2S in the gaseous fuel. 

(2) Have the span value of the monitor set so that all readings fall between 20 and 95 percent of 

scale. 

(3) Check for calibration drift of the monitoring system at least once daily (approximately 24-hr 

interval) at two concentrations, one high level and one low level. Whenever the daily high level 

or low level calibration drift exceeds 5% of analyzer full scale span, the monitoring system 

shall be deemed to be out of control and subject to the requirements of subparagraph 

(dsubsection (D)(4)(Bb) of this rule. 

(4) Determine the relative accuracy of the monitor which shall be no greater than 20 percent of the 

mean value of the reference method test data. 

(5) Be able to record negative values of zero drift. 

(6) Report the concentration of the sulfur compounds calculated as hydrogen sulfideH2S. 

SECTION II - 

REQUIREMENTS FOR CONTINUOUS 

EMISSIONS MONITORING SYSTEMS (CEMS) 

A stack CEMS used for monitoring the sulfur dioxide emissions from the burning of any gaseous fuel 

shall: 

(1) Continuously monitor and record the concentration by volume (dry basis, zero percent excess 

air) of sulfur compounds in ppmv as SO2 emitted into the atmosphere; 

(2) Include either an oxygen monitor for correcting the data for excess air or a fuel gas and exhaust 

gas flowmeter for the determination of mass emissions; 

(3) Have the span value of all the monitors set so that all readings fall between 20 and 95 percent, 

for four-hour and daily averages, and between 10 and 95 percent, for monthly averages, of full 

scale; 

(4) When using an oxygen monitor for the correction of excess air, be able to measure a sulfur 

compound concentration emission limit of 5 ppm (dry basis, zero percent excess air), which is 

stoichiometrically equivalent to the limit of sulfur compound content of 40 ppm calculated as 

hydrogen sulfide in the gaseous fuels; 

(5) Use District Methods 100.1 or 6.1 (as applicable for sulfur compound analysis) and 

DistrictSCAQMD Method 3.1 (for oxygen content analysis), or DistrictSCAQMD Method 2.1 
431.1-14 AVAQMD Rule 431.1 

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(for flowrate determination), whichever is applicable, or any other methods demonstrated by the 

applicant to be equivalent and approved in writing by the Executive Officers of the 

DistrictAPCO and the CARB, and the Regional Administrator of the EPA, Region IX, or their 

designees, for conducting the relative accuracy evaluations. The relative accuracy limit shall be 

1 ppm and zero drift (2-hour and 24-hour) and calibration drift (2-hour and 24-hour) limits for 

sulfur compounds monitor shall be 5 percent of the span range; and 

(6) Check for calibration drift of the monitoring system at least once daily (approximately 24-hr 

interval) at two concentrations, one high level and one low level. Whenever the daily high level 

or low level calibration drift exceeds 5% of analyzer full scale span, the monitoring system 

shall be deemed to be out of control and subject to the requirements of subparagraph 

(dsubsection (D)(4)(Bb) of this rule. 

(7) Facilities burning fuel gas subject to this rule shall comply with the requirements of Rule 218 

and 218.1(proposed) except where specific requirements have been incorporated into this rule. 

SECTION III - –

GUIDELINES FOR APPROVAL OF 

ALTERNATIVE MONITORING PLAN

BY THE EXECUTIVE OFFICERAPCO

In lieu of a continuous fuel gas monitoring system (CFGMS) or a continuous emission monitoring 

system (CEMS), a person subject to this rule may submit an alternative monitoring plan to the 

Executive Officer or designeeAPCO, the California Air Resources Board (CARB), and the Regional 

Administrator of the Environmental Protection Agency (EPA), Region IX, or their designees. for 

histheir review and decision. Submittal of such a plan must be at least 180 days prior to the applicable 

compliance date set forth in Table 1. The Executive Officer or designee shall approve or disapprove of 

such plan no later than 90 days prior to the applicable compliance date set forth in Table 1 based upon 

whether the alternative monitoring plan includes all of the following:

(1) A test program to determine the correlation between hydrogen sulfideH2S and total sulfur in the 

fuel gas using DistrictSCAQMD Method 307-91. If a correlation is established, a colorimetric 

test, or other alternative method approved by the Executive Officer or designeeAPCO as being 

equivalent or better in establishing such correlation, may be conducted regularly to determine 

total sulfur using hydrogen sulfideH2S as a surrogate. 

(2) An error analysis between colorimetric, or other approved alternative method readings and the 

total reduced sulfur analysis obtained from DistrictSCAQMD Method 307-91. To demonstrate 

equivalency between the two methods of analyses, the relative accuracy shall not exceed 20 

percent of average DistrictSCAQMD Method 307-91 readings. 

(3) A schedule for a daily or more frequent analysis of the fuel gas for hydrogen sulfide (H2S)

using the colorimetric test, or other approved alternative method, and a minimum weekly 

analysis of the fuel gas using DistrictSCAQMD Method 307-91. A different frequency of 

analysis may be used if the Executive Officer or designeeAPCO determines that such frequency 

is adequate towill ensure compliance with the daily total sulfur limits of this rule. 
AVAQMD Rule 431.1 431.1-15

Sulfur Content of Gaseous Fuels 

D1b: 03/29/12 

(4) When the sulfur level is suspected to be at or above the 40 ppmv levelsulfur content 

requirements of Table 1 as determined by the colorimetric or other alternative method, a 

procedure to obtain at minimum a daily sample to be tested according to DistrictSCAQMD

Method 307-91 until three consecutive daily samples show that total sulfur is below the 40 

ppmv limitsulfur content requirements of Table 1.