STATE OF RHODE ISLAND AND PROVIDENCE PLANTATIONS

DEPARTMENT OF ENVIRONMENTAL MANAGEMENT

OFFICE OF AIR RESOURCES

AIR POLLUTION CONTROL REGULATION NO. 27

CONTROL OF NITROGEN OXIDE EMISSIONS 

Effective 1 February 1994

Last Amended 19 July 2007

AUTHORITY: These regulations are authorized pursuant to R.I. Gen. Laws § 42-17.1-2(s) and 23-23,

as amended, and have been promulgated pursuant to the procedures set forth in the R.I. Administrative 

Procedures Act, R.I. Gen. Laws Chapter 42-35.
RHODE ISLAND DEPARTMENT OF ENVIRONMENTAL MANAGEMENT

OFFICE OF AIR RESOURCES

AIR POLLUTION CONTROL REGULATION NO. 27

CONTROL OF NITROGEN OXIDE EMISSION

TABLE OF CONTENTS

27.1 Definitions....................................................................................................................................................1

27.2 Applicability and Exemptions.......................................................................................................................3

27.3 Reasonably Available Control Technology (RACT) Plan Requirements .......................................................3

27.4 Reasonably Available Control Technology (RACT) Requirements...............................................................6

27.5 Compliance Testing and Emission Monitoring Requirements......................................................................10

27.6 Recordkeeping and Reporting Requirements...............................................................................................12

27.7 General Provisions......................................................................................................................................16

APPENDIX A..............................................................................................................................................................18
Page 1 of 20

RHODE ISLAND DEPARTMENT OF ENVIRONMENTAL MANAGEMENT

OFFICE OF AIR RESOURCES

AIR POLLUTION CONTROL REGULATION NO. 27

CONTROL OF NITROGEN OXIDES EMISSIONS

27.1 Definitions

Unless otherwise expressly defined in this section, the terms used in this regulation shall be 

defined by reference to the Rhode Island Air Pollution Control General Definitions 

Regulation. As used in this regulation, the following terms shall, where the context permits, 

be construed as follows:

27.1.1 "Actual emissions" means the actual rate of emissions of a pollutant from a 

piece of equipment or a pollutant-emitting activity as determined in 

accordance with Subsections (a) through (c) below:

(a) In general, actual emissions as of a particular date shall equal the 

average rate, in tons per year, at which the unit actually emitted the 

pollutant during a two year period which precedes the particular date 

and which is representative of normal stationary source operation. 

Actual emissions shall be calculated using the equipment's or 

activity's actual operating hours, production rates and types of 

materials processed, stored or combusted during the selected time 

period;

(b) The Director may presume that stationary source specific allowable 

emissions for the equipment or activity are equivalent to the actual 

emissions of the equipment or activity;

(c) For any equipment or activity which has not begun normal 

operations on the particular date, actual emissions shall equal the 

potential to emit of the equipment or activity on that date.

27.1. 2 "Combined cycle gas turbine" means any stationary gas turbine which 

recovers heat from the gas turbine exhaust gases to heat water or generate 

steam.

27.1. 3 "Combustion turbine" means any simple cycle gas turbine or any

combined cycle gas turbine including the duct burner portion thereof.

27.1.4 "Emergency standby internal combustion engine" means an internal 

combustion engine operated only as a mechanical or electrical power source 

for a stationary source when the primary power source has been rendered 
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inoperable. This does not include power interruptions pursuant to an 

interruptible power service agreement.

27.1.5 "Equivalent control" means a control system that may be substituted for 

the required control system(s). The stationary source applying to use an 

equivalent control must demonstrate to the satisfaction of the Division and 

EPA that the emission reductions achieved are equal to or greater than the 

emission reductions required by the regulation. Appropriate test methods or 

other replicable criteria in accordance with Department and EPA guidance 

must be used to demonstrate equivalence.

27.1.6 "Industrial-Commercial-Institutional Boiler" means a device that 

combusts any fuel and produces steam or heats water or any other heat 

transfer medium. This term does not include utility boilers used by electric 

utilities to generate electricity.

27.1.7 "Internal combustion engine" means any engine in which power, 

produced by heat and/or pressure developed in the engine cylinder(s) by

burning a mixture of air and fuel, is subsequently converted to mechanical 

work by means of 1 or more pistons.

27.1.8 "Lean-burn engine" means an internal combustion engine where the 

amount of oxygen in the exhaust gases is 1% or more, by weight.

27.1.9 "Liquified petroleum (LP) gas" means liquified petroleum gas as defined 

by the American Society for Testing and Materials in ASTM D1835-82, 

"Standard Specification for Liquified Petroleum Gases".

27.1.10 "Low NOx burner" means a commercially available modified combustion 

burner designed to minimize NOx formation through low excess air firing, 

controlled mixing of primary combustion air and fuel (staged air or staged 

fuel), reducing peak furnace temperature or other burner designs judged to 

be low NOx burners by the Division and EPA based on a review of evidence 

submitted by the subject stationary source.

27.1.11 "Rich-burn engine" means an internal combustion engine where the 

amount of oxygen in the engine exhaust gases is less than 1% by weight.

27.1.12 “Simple cycle gas turbine" means any stationary gas turbine which does 

not recover heat from the gas turbine exhaust gases to preheat the inlet 

combustion air to the gas turbine, or which does not recover heat from the 

gas turbine exhaust gases to heat water or generate steam.

27.1.13 "Utility boiler" means a device, with a heat input capacity of 250 million 

Btu per hour or greater, that combusts any fuel and produces steam for the 
Page 3 of 20

primary purpose of generating electricity. This term does not include 

combustion turbines.

27.2 Applicability and Exemptions

27.2.1 This regulation applies to all stationary sources which have or ever have had, 

since 1 January 1990, the potential to emit 50 tons of nitrogen oxides (NOx) 

per year from all pollutant-emitting equipment or activities.

27.2.2 A stationary source with potential yearly emissions of 50 tons or more of 

NOx, but with actual emissions not exceeding 50 tons per year of NOx any

time after 1 January 1990, may apply to the Director for an exemption from 

Sections 27.4 and 27.5 of this regulation. Application for an exemption 

must be submitted to the Director by 1 July 1994, and must include 

documentation of previous yearly NOx emissions, in tons per year, since 1 

January 1990. Exemption from Section 27.4 of this regulation will be in the 

form of an enforceable document issued by the Director which limits actual 

emissions to less than 50 tons per year of NOx and shall include, but not 

necessarily be limited, to the following conditions:

(a) Actual annual emissions shall not exceed 50 tons of NOx per year, 

and

(b) The stationary source shall meet the emission cap over every

consecutive 12 month period. Recordkeeping to demonstrate 

compliance shall be conducted as provided in Section 27.6.9 and 

shall be kept on a monthly basis. The cap must be consistent with 

the anticipated level of emissions in the approved State 

Implementation Plan (SIP).

Any stationary source that has been issued an emissions cap and fails to 

meet the requirements of the enforceable document must immediately be in 

compliance with RACT.

27.2.3 Any emergency standby internal combustion engines which is operated less 

than 500 hours during any consecutive twelve (12) month period is exempt 

from Section 27.4 of this regulation. Recordkeeping shall be conducted as 

provided in Subsection 27.6.10.

Any emergency standby internal combustion engine operated under the 

provisions of this subsection must immediately be in compliance with 

RACT if the hours of operation in any twelve (12) month period exceeds 

500.

27.3 Reasonably Available Control Technology (RACT) Plan Requirements
Page 4 of 20

27.3.1 Any stationary source subject to the provisions of Section 27.4 of this 

regulation shall, by 3 October 1994 or six months after becoming a potential 

50 tons per year NOx stationary source, whichever is later, submit to the 

Director a RACT proposal for approval which includes all information 

specified in Subsections 27.3.2 or 27.3.3.

27.3.2 All RACT proposals submitted to comply with Subsection 27.4.1, 27.4.2 or 

27.4.3 shall include the following information:

(a) an inventory of all NOx - emitting equipment with a heat input 

capacity greater than or equal to one million Btu per hour at the 

stationary source

(b) the maximum capacity, in millions of Btu per hour, of each piece of 

NOx - emitting equipment

(c) the type of fuel or fuels combusted in each piece of NOx - emitting 

equipment

(d) the maximum NOx emission rate for each piece of NOx - emitting 

equipment in lbs per million Btu for each fuel burned

(e) the actual amount of NOx emitted for each calendar year since 1 

January 1990, from each piece of NOx - emitting equipment

(f) a summary of the applicable emission limits and requirements of this 

regulation and how the stationary source will comply

(g) a schedule for the implementation of RACT, including dates for each 

of the following where applicable: completion of engineering, 

awarding of contracts, initiation of construction, completion of 

construction and final compliance with RACT

(h) any additional information requested by the Director

27.3.3 All RACT proposals submitted to comply with Subsection 27.4.4 or 27.4.9 

shall include the following information:

(a) an inventory of all NOx - emitting equipment with a heat input 

capacity greater than or equal to one million Btu per hour at the 

stationary source

(b) the maximum capacity, in million of Btu per hour, of each piece of 

NOx - emitting equipment
Page 5 of 20

(c) the type of fuel or fuels combusted in each piece of NOx - emitting 

equipment

(d) the maximum NOx emission rate for each piece of NOx - emitting 

equipment, in lbs per million Btu, for each fuel burned

(e) the actual amount of NOx emitted for each calendar year since 1 

January 1990, from each piece of NOx - emitting equipment

(f) an examination of the technical and economic feasibility of available 

NOx control techniques for each piece of NOx - emitting equipment 

with the potential to emit 10 tons or more of NOx per year.

(g) the control option or combination of control options selected as 

RACT, including emission limits and the test methods to be used to 

demonstrate compliance

(h) the amount of reduction in NOx emissions that will be associated 

with implementing the selected control option(s)

(i) a schedule for the implementation of RACT, including dates for each 

of the following where applicable: completion of engineering, 

awarding of contracts, initiation of construction, completion of 

construction and final compliance with RACT

(j) the testing, monitoring, record keeping and reporting procedures to 

be used to demonstrate continuous compliance

(k) any additional information requested by the Director that is deemed 

necessary to determine RACT

27.3.4 After reviewing a RACT proposal submitted to comply with Subsection 

27.4.1, 27.4.2 or 27.4.3 the Division will issue a final approval or 

disapproval of the proposal.

27.3.5 After reviewing a RACT proposal submitted to comply with Subsection 

27.4.4, the Division, in consultation with the EPA, shall prepare a proposed 

enforceable document specifying RACT for the stationary source. The 

enforceable document shall be subject to a thirty day public comment 

period. A public hearing for interested persons to appear and to submit 

written or oral comments on the enforceable document shall be held upon 

request. The Director may also hold a hearing at his or her discretion, 

whenever he or she believes there is a significant degree of public interest in 

the proposed action. If held, a hearing shall take place no earlier than thirty
Page 6 of 20

(30) days nor later than sixty (60) days following initial public notice. 

Comments from the stationary source and/or any interested persons shall be 

recorded at the public hearing. Written comments, to be considered part of 

the record, must be submitted during the public comment period. The public 

comment period shall commence on the date of initial public notice. The 

public comment period shall close thirty (30) days later, if no public hearing 

is held. If a public hearing is held, the public comment period shall close at 

the close of the public hearing or on a later date set by the Division. The 

final enforceable document shall be submitted to the EPA for approval as a 

source specific revision to the State Implementation Plan.

27.4 Reasonably Available Control Technology (RACT) Requirements

27.4.1 Utility Boilers

On and after 31 May 1995, no person shall cause or allow the emission of 

NOx from any utility boiler in excess of the following emission limitations:

(a) 0.20 lbs per million Btu of actual heat input when operated on 

natural gas or liquified petroleum gas (LP)

(b) 0.25 lbs per million Btu of actual heat input when operated on fuel 

oil

27.4.2 Industrial - Commercial - Institutional Boilers

(a) On and after 31 May 1995, no person shall cause or allow the 

emission of NOx from any Industrial - Commercial - Institutional 

boiler, fired with natural gas or distillate oil, with a heat input 

capacity of 50 million Btu per hour or greater, in excess of the 

following emission limitations:

1. 0.10 lbs per million Btu of actual heat input when operated 

on natural gas

2. 0.12 lbs per million Btu of actual heat input when operated 

on distillate oil or liquified petroleum gas (LP)

(b) On and after 31 May 1995, no person shall cause or allow the 

emission of NOx from any Industrial - Commercial - Institutional 

boiler, fired with residual oil, with a heat input capacity of 50 million 

Btu per hour or greater, unless the boiler is equipped with low - NOx

burners and flue gas recirculation (with a minimum of 10% flue gas 

recirculation) or equivalent control.
Page 7 of 20

(c) On and after 31 May 1995, no person shall cause or permit the 

emission of NOx from any Industrial - Commercial - Institutional 

boiler, with a heat input capacity of 1 million Btu per hour or greater, 

but less than 50 million Btu per hour, unless the boiler is tuned at 

least once per year in accordance with the procedure described in 

Appendix A.

27.4.3 Internal Combustion Engines

On and after 31 May 1995, no person shall cause or permit the emission of 

NOx from any internal combustion engine, capable of producing 400 

horsepower (HP) or more, in excess of the following emission limitations:

(a) Rich-burn Engines

1. 1.5 grams per brake horsepower-hour when operated on 

natural gas

(b) Lean-burn Engines

1. 2.5 grams per brake horsepower-hour when operated on 

natural gas

2. 9.0 grams per brake horsepower-hour when operated on fuel 

oil

27.4.4 Miscellaneous Stationary Sources

(a) Any stationary source, equipment or pollutant emitting activity, with 

the potential to emit 10 tons or more of NOx per year, that is not 

covered by Subsection 27.4.1, 27.4.2 or 27.4.3 shall install and 

operate in compliance with RACT, as specified in an enforceable 

document issued by the Director, by 31 May 1995.

(b) Any stationary source that becomes a potential 50 ton per year NOx

stationary source after 30 November 1993 shall install and operate in 

compliance with RACT, within 18 months of the date that the 

stationary source first becomes a potential 50 ton per year NOx

stationary source. RACT shall be specified in an enforceable 

document issued by the Director.

27.4.5 The RACT requirements in Subsections 27.4.1 - 27.4.4 do not apply to equipment 

and pollutant - emitting activities that have been determined to be BACT or 

LAER in any permit issued by the Division pursuant to Air Pollution 

Control Regulation No. 9 since 15 November 1992.
Page 8 of 20

27.4.6 The RACT requirements in Subsection 27.4.3 or 27.4.4 do not apply to 

equipment and pollutant emitting activities listed below, that have been 

issued a permit for the construction/installation of new equipment by the 

Division, pursuant to Air Pollution Control Regulation No.9, since the 

indicated date.

(a) Combustion turbine facilities - 6 January 1989

(b) Internal combustion engines - 28 September 1989

(c) Fluidized bed boilers - 11 March 1991

27.4.7 The RACT requirements in Subsection 27.4.1 do not apply to any utility

boiler that commits, by 3 October 1994, in an enforceable document, to 

either permanently shut down and dismantle that existing utility boiler by 31 

May 1995 or replace that existing utility boiler by 31 December 1996 as part 

of a repowering project. The repowered emissions unit(s) must meet a NOx

emission limitation that has been determined to be BACT or LAER in a 

permit issued by the Division pursuant to Air Pollution Control Regulation 

No. 9. In addition to the commitment, the source must comply with the 

alternative RACT requirements of 27.4.8. The final enforceable document 

and the alternative RACT determination shall be submitted to the EPA for 

approval as a source specific revision to the State Implementation Plan 

(SIP).

27.4.8 Alternative RACT

(a) The RACT requirements in Subsection 27.4.1 -27.4.3 may be 

relaxed on a case-by-case basis, if by 3 October 1994 or six months 

after becoming a potential 50 ton per year NOx stationary source, the 

owner or operator makes application to the Division for an 

alternative RACT determination. An application for an alternative 

RACT determination must include the following:

1. an inventory of all NOx - emitting equipment with a heat 

input capacity greater than or equal to one million Btu per 

hour at the stationary source

2. the maximum capacity, in million of Btu per hour, of each 

piece of NOx - emitting equipment

3. the type of fuel or fuels combusted in each piece of NOx -

emitting equipment
Page 9 of 20

4. the maximum NOx emission rate for each piece of NOx -

emitting equipment, in lbs per million Btu, for each fuel 

burned

5. the actual amount of NOx emitted for each calendar year 

since 1 January 1990, from each piece of NOx - emitting 

equipment

6. economic and/or technical documentation that demonstrates 

to the satisfaction of the Division and EPA that the 

applicable emission limitations cannot feasibly be met.

7. an examination of the technical and economic feasibility of 

alternative NOx control techniques for each piece of NOx

emitting equipment

8. The control option or combination of control options 

proposed as alternative RACT, including emission limits and 

test methods to demonstrate compliance.

9. The amount of reduction in NOx emissions that will be 

associated with implementing the selected control option(s).

10. A schedule for the implementation of alternative RACT, 

including dates for each of the following where applicable: 

completion of engineering, awarding of contracts, initiation 

of construction, completion of construction and final 

compliance with alternative RACT by 31 May 1995.

11. The testing, monitoring, recordkeeping and reporting 

procedures to be used to demonstrate continuous compliance.

12. Any additional information requested by the Director that is 

deemed necessary to determine alternative RACT.

(b) Any alternative RACT determination will not become final until 

approved by EPA as a source specific State Implementation Plan 

(SIP) revision;

(c) The stationary source shall conduct a RACT review every three years 

after the final compliance date until the RACT requirements in 

Subsections 27.4.1, 27.4.2 or 27.4.3 are achieved. This RACT 

review must include the same information required in an application 

for an alternative RACT determination. This RACT review will not 

become final until approved by EPA as a source specific State 
Page 10 of 20

Implementation Plan (SIP) revision.

27.4.9 Fuel Switching

Any facility subject to the RACT requirements in Subsections 27.4.1 -

27.4.4 may propose to comply with those requirements by fuel switching. 

Fuel switching refers to instances where a piece of NOx emitting equipment 

historically burned one primary fuel, such as residual oil, and under a fuel 

switching program, the equipment would burn a cleaner fuel, such as natural 

gas, during the ozone season (May 1 - September 30) and may switch back 

to the historic fuel for some or all of the non-ozone season.

(a) The owner or operator of a stationary source proposing a fuel 

switching program must file an application with the Division for 

approval of a fuel switching program no later than 3 October 1994 or 

six months after becoming a potential 50 ton per year NOx facility, 

whichever is later.

(b) An application for approval of a fuel switching program must 

demonstrate that the NOx reductions achieved will be the equivalent 

of that which would be achieved if the stationary source were 

operating in compliance with its applicable emission limitations 

throughout the year.

(c) An application for approval of a fuel switching program must 

demonstrate that the program uses a long term emissions averaging 

approach consistent with the Environmental Protection Agency's 

guidance. This guidance is contained in a 30 July 1993 memo from 

Michael Shapiro entitled "Fuel Switching to Meet the Reasonably

Available Control Technology Requirements for Nitrogen Oxides".

(d) Any fuel switching program will not become final until approved by

EPA as a source specific State Implementation Plan (SIP) revision.

27.5 Compliance Testing and Emission Monitoring Requirements

27.5.1 Compliance with Subsections 27.4.1 and 27.4.9 shall be demonstrated by

installation calibration, maintenance and operation of a continuous emission 

monitoring system for NOx and O2 or CO2.

27.5.2 Compliance with Subsections 27.4.2(a) - (b), 27.4.3, 27.4.4, and 27.4.8 shall 

be demonstrated either by emission testing or by installation calibration, 

maintenance and operation of a continuous emission monitoring system for 

NOx and O2 or CO2.
Page 11 of 20

27.5.3 Compliance with Subsection 27.4.2 (c) shall be demonstrated by record 

keeping as specified in Subsection 27.6.8.

27.5.4 Compliance with the emission limitations in Subsections 27.4.1 shall be 

based on 24 hour average concentrations.

27.5.5 Compliance with the emission limitations in Subsections 27.4.2 and 27.4.3 

shall be based on one hour average concentrations. Emission testing shall 

consist of 3 - one hour test runs. Compliance with the emission limitation 

must be demonstrated for each test run.

27.5.6 Continuous emission monitoring systems shall comply with the following 

requirements:

(a) Performance specification, monitor location, calibration and 

operating procedures, quality assurance procedures for each monitor 

and a sample calculation showing how the concentrations from the 

NOx CEMs will be converted in to the applicable units and 

averaging time of the emission limit must be submitted to the 

Division for review and approval at least 180 days prior to expected 

installation.

(b) All emission data shall be continuously monitored and recorded.

(c) The continuous emission monitors must satisfy the requirements of 

40 CFR 60 Appendix B, Performance Specification 2.

(d) The continuous emission monitors must satisfy the quality assurance 

requirements of 40 CFR 60, Appendix F.

(e) The continuous emission monitoring system will be used to 

determine compliance with the applicable allowable NOx emission 

rates.

(f) The stationary source shall have the capability of transmitting all of 

the collected continuous emission monitoring data to the Division's

office via a telemetry system.

(g) Each continuous emission monitoring system shall be operated at all 

times except for periods of CEMs calibration checks, zero and span 

adjustment and preventative maintenance. Notwithstanding such 

exceptions, in all cases valid CEMs data shall be obtained for at least 

75% of the hours per day, 75% of the days of the month and 90% of 

the hours per quarter that the stationary source is operating.
Page 12 of 20

27.5.7 Emissions testing shall comply with the following requirements:

(a) Emissions testing shall be conducted by 30 November 1995, initially

and annually thereafter to demonstrate compliance with the 

applicable NOx emission limitation

(b) An emissions testing protocol shall be submitted to the Division for 

review and approval prior to the performance of any tests. The 

Division shall be notified at least 60 days prior to any emissions test.

(c) All test procedures used for emissions testing shall be in accordance 

with the methods set forth in Appendix A of 40 CFR 60 or another 

method approved by the Division and the EPA.

(d) The owner or operator of the stationary source shall install any and 

all test ports or platforms necessary to conduct the required 

emissions testing, provide safe access to any platforms and provide 

the necessary utilities for sampling and testing equipment.

(e) All testing shall be conducted under operating conditions deemed 

acceptable and representative for the purpose of assessing 

compliance with the applicable emission limitation.

(f) All emissions testing must be observed by the Division or its 

authorized representative to be considered acceptable.

(g) A final report of the results of emissions testing shall be submitted to 

the Division no later than 60 days following completion of the 

testing.

27.6 Recordkeeping and Reporting Requirements

27.6.1 A record of all measurements, performance evaluations, calibration checks, 

and maintenance or adjustments for each continuous emission monitor shall 

be maintained.

27.6.2 A written report of excess emissions as measured by a continuous emission 

monitor shall be submitted to the Division for every calendar quarter. All 

quarterly reports shall be received no later than 30 days following the end of 

each calendar quarter and shall include the following information:

(a) The date and time of commencement and completion of each period 

of excess emissions and the magnitude of the excess emissions

(b) Identification of the suspected reason for the excess emissions and 
Page 13 of 20

any corrective action taken.

(c) The date and time period any continuous emission monitor was 

inoperative, except for zero and span checks and the nature of system

repairs or adjustments.

(d) The date and time periods of any missing data or periods where 

compliance could not be determined and the steps taken to cure the 

cause of the missing data.

In the event none of the above items have occurred such information shall be 

stated in the report.

27.6.3 The fuel used in each combustion unit subject to RACT must be measured 

and recorded monthly.

As an alternative to measuring and recording fuel used in each combustion 

unit, a stationary source may petition the Division to use one of the 

following methods to demonstrate compliance with RACT:

(a) The fuel used in multiple combustion units which have equivalent 

NOx emission rates may be measured and recorded monthly using a 

single metering device. If more than one type of fuel is used in the 

multiple combustion units the amount of each type fuel must be 

measured and recorded monthly;

(b) The fuel used in multiple combustion units which have different 

NOx emission rates may be measured and recorded monthly using a 

single metering device. If more than one type of fuel is used in the 

multiple combustion units the amount of each type fuel must be 

measured and recorded monthly. The total NOx emissions for these 

units will be determined using the emission rate of the highest NOx

emitting combustion unit.

27.6.4 Stationary sources subject to Subsection 27.4.2 (a)(2) shall obtain a 

certification from the fuel supplier for each shipment of distillate oil that 

includes the following information:

(a) The name of the oil supplier, and;

(b) That the oil complies with the specification for fuel oil numbers 1 or 

2, as defined by the American Society for Testing and Materials in 

ASTM D396-78 "Standard Specification for Fuel Oils"

27.6.5 All stationary sources combusting residual fuel oil shall obtain a certification 
Page 14 of 20

from the fuel supplier for each shipment of residual oil that includes the 

following information:

(a) The name of the oil supplier;

(b) The nitrogen content of the oil from which the shipment came or of 

the shipment itself;

(c) The method used to determine the nitrogen content of the oil. 

ASTM test methods D3228, D4629 or any other method approved 

by the Division and the EPA may be used; and,

(d) The location of the oil when the sample was drawn for analysis to 

determine the nitrogen content of the oil, specifically including 

whether the oil was sampled as delivered to the stationary source or 

whether the sample was drawn from oil in storage at the oil 

supplier's or oil refiner's facility or another location.

27.6.6 As an alternative to the fuel supplier certification required in Subsection 

27.6.5, a stationary source may elect to sample the fuel oil prior to 

combustion. Sampling and analysis shall be conducted after each new 

shipment of residual oil is received. Samples shall be collected from the fuel

tank immediately after the fuel tank is filled and before any oil is combusted. 

The residual oil must be sampled and analyzed according to ASTM 

methods which have the prior approval of or are required by the Director.

27.6.7 Copies of all fuel supplier certifications or fuel oil analyses shall be 

maintained at the facility and be made accessible for review by the Director 

or the designated personnel of the Director and EPA. These records shall 

include a certified statement, signed by the owner or operator of the 

stationary source, that the records represent all of the fuel combusted during 

the quarter.

27.6.8 All stationary sources subject to Subsection 27.4.2 (c) shall maintain records 

verifying that a tune-up has been performed in accordance with the 

procedure described in Appendix A that includes the following information:

(a) The date the tune-up was performed;

(b) The name of the person who performed the tune-up; and,

(c) The final excess oxygen setting.

(d) The O2/CO curve or O2/smoke curve that has been developed as part 

of this procedure.
Page 15 of 20

27.6.9 Stationary sources subject to an emissions cap pursuant to the provisions of

Subsection 27.2.2 shall:

(a) Measure and record monthly the fuel used in each combustion unit 

with a heat input capacity greater than or equal to one million Btu 

per hour;

(b) On a monthly basis, no later than fifteen (15) days after the first of 

each month, determine the fuel usage and quantity of NOx emitted 

for the previous twelve (12) month period for each combustion unit 

or for the stationary source;

(c) Notify the Division, in writing within 30 days of the end of the 

month, whenever NOx emissions exceed the emissions cap; or,

(d) As an alternative to measuring and recording fuel used in each 

combustion unit as required in 27.6.9 (a), a stationary source may

petition the Division to use one of the following methods to 

demonstrate compliance with an emissions cap:

(1) The fuel used in multiple combustion units which have 

equivalent NOx emission rates may be measured and 

recorded monthly using a single metering device. If more 

than one type of fuel is used in the multiple combustion units 

the amount of each type fuel must be measured and recorded 

monthly;

(2) The fuel used in multiple combustion units which have 

different NOx emission rates may be measured and recorded 

monthly using a single metering device. If more than one 

type of fuel is used in the multiple combustion units the 

amount of each type fuel must be measured and recorded 

monthly. The total NOx emissions for these units will be 

determined using the emission rate of the highest NOx

emitting unit.

27.6.10 All stationary sources with emergency standby internal combustion engines 

satisfying the provisions of Subsection 27.2.3 shall:

(a) Notify the Division, in writing, by 31 May 1995 of:

(1) the maximum capacity, in millions of Btu per hour, of each 

emergency standby internal combustion engine at the 

stationary source; and,
Page 16 of 20

(2) the type of fuel or fuels combusted in each engine;

(b) Install and maintain a non-resetable elapsed time meter to indicate, 

in cumulative hours, the elapsed engine operating time;

(c) On a monthly basis, no later than five (5) days after the first of each 

month, determine and record the hours of operation for each engine 

for the previous twelve (12) month period;

(d) Notify the Division, in writing, whenever the hours of operation in 

any twelve (12) month period exceeds 500 hours; and

(e) Maintain records to certify that the ignition timing of the engine has 

been inspected and adjusted at least once every three (3) years.

27.6.11 All records required in this Subsection shall be maintained at the stationary

source for a minimum of five (5) years and shall be made available to 

representatives of the Department or EPA upon request.

27.7 General Provisions

27.7.1 Purpose

The purpose of this regulation is to limit emissions of nitrogen oxides from 

stationary sources

27.7.2 Authority

These regulations are authorized pursuant to R.I. Gen. Laws § 42-17.1-2(s) 

and 23-23, as amended, and have been promulgated pursuant to the 

procedures set forth in the R.I. Administrative Procedures Act, R.I. Gen. 

Laws Chapter 42-35

27.7.3 Application

The terms and provisions of this regulation shall be liberally construed to 

permit the Department to effectuate the purposes of state law, goals and 

policies.

27.7.4 Severability

If any provision of this regulation or the application thereof to any person or 

circumstance, is held invalid by a court of competent jurisdiction, the 
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validity of the remainder of the regulation shall not be affected thereby.

27.7.5 Effective Date

The foregoing regulation, "Control of Nitrogen Oxide Emissions”, as 

amended, after due notice, is hereby adopted and filed with the Secretary of 

State this __29th___ day of __June_________, 2007_ to become effective 

twenty (20) days thereafter, in accordance with the provisions of Chapters 

23-23, 42-35, 42-17.1, 42-17.6, of the General Laws of Rhode Island of 

1956, as amended.

W. Michael Sullivan, PhD., Director

Department of Environmental Management

Notice Given on: February 21, 2007

Public Hearing held: March 23, 2007

Filing Date: June 29, 2007

Effective Date: July 19, 2007
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APPENDIX A

EQUIPMENT TUNING PROCEDURE1

Nothing in this Equipment Tuning Procedure shall be construed to require any act or omission that 

would result in unsafe conditions or would be in violation of any regulation or requirement 

established by Factory Mutual, National Fire Prevention Association, the Rhode Island Department 

of Labor (Division of Occupational Safety), the Federal Occupational Safety and Health 

Administration or other relevant regulations or requirements.

1. Operate the unit at the firing rate most typical of normal operation. If the unit experiences 

significant load variations during normal operation, operate it at its average firing rate.

2. At this firing rate, record stack gas temperature, oxygen concentration and CO concentration 

(for gaseous fuels) or smoke-spot number2(for liquid fuels) and observe flame conditions 

after the unit stabilizes at the firing rate selected. If the excess oxygen in the stack gas is at 

the lower end of the range of typical minimum values3, and if the CO emissions are low and 

there is no smoke, the unit is probably operating at near optimum efficiency - at this 

particular firing rate. However, complete the remaining portion of this procedure to 

determine whether still lower oxygen levels are practical.

3. Increase combustion air flow to the furnace until stack gas oxygen levels increase by one to 

two percent over the value measured in Step 2. As in Step 2, record the stack gas 

temperature, CO concentration (for gaseous fuels) or smoke-spot number (for liquid fuels) 

and observe flame conditions for these higher oxygen levels after boiler operation stabilizes.

4. Decrease combustion air flow until the stack gas oxygen concentration is at the level 

measured in Step 2. From this level gradually reduce the combustion air flow in small 

increments. After each increment, record the stack gas temperature, oxygen concentration, 

CO concentration (for gaseous fuels) and smoke-spot number (for liquid fuels). Also 

observe the flame and record any changes in its condition.

5. Continue to reduce combustion air flow stepwise until one of these limits is reached:

a. Unacceptable flame conditions - such as flame impingement on furnace walls or 

burner parts, excessive flame carryover or flame instability.

b. Stack gas CO concentration greater than 400 ppm.

c. Smoking at the stack.

d. Equipment related limitations - such as low windbox/furnace pressure differential, 

built in air flow limits, etc.

6. Develop an O2/CO curve (for gaseous fuels) or O2/smoke curve (for liquid fuels) similar to 
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those in Figures 1 and 2 using the excess oxygen and CO or smoke-spot number data 

obtained at each combustion air flow setting.

7. From the curves prepared in Step 6, find the stack gas oxygen levels where the CO 

emissions or smoke-spot number equal the following values:

Fuel Measurement Value

Gaseous CO emissions 400 ppm

#1 & #2 oils smoke-spot number number 1

#4 oil smoke-spot number number 2

#5 oil smoke-spot number number 3

#6 oil smoke-spot number number 4

The above conditions are referred to as CO or smoke threshold, or as the minimum excess 

oxygen level.

Compare this minimum value of excess oxygen to the expected value provided by the 

combustion unit manufacturer. If the minimum value found is substantially higher than the 

value provided by the combustion unit manufacturer, burner adjustments shall be made to 

improve fuel and air mixing, thereby allowing operation with less air.

8. Add 0.5 to 2.0 percent to the minimum excess oxygen level found in Step 7 and reset burner 

controls to operate automatically at this higher stack gas oxygen level. This margin above 

the level accounts for fuel variations, variations in atmospheric conditions, load changes and 

non repeatability or play in automatic controls.

9. If the load of the combustion unit varies significantly during normal operation, repeat Steps 

1-8 for firing rates that represent the upper and lower limits of the range of the load. 

Because control adjustments at one firing rate may affect conditions at other firing rates, it 

may not be possible to establish the optimum excess oxygen level at all firing rates. If this 

is the case, choose the burner control settings that give the best performance over the range 

of firing rates. If one firing rate predominates, settings should optimize conditions at that 

rate.

10. Verify that the new settings can accommodate the sudden changes that may occur in daily

operation without adverse affects. Do this by increasing and decreasing load rapidly while 

observing the flame and stack. If any of the conditions in Step 5 result, reset the 

combustion controls to provide a slightly higher level of excess oxygen at the affect firing 

rates. Next, verify these new settings in a similar fashion. Then make sure that the final 

control settings are recorded at steady state operating conditions for future reference.
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_________________________________________________________________

1. This tuning procedure is based on a tune-up procedure developed by KVB Inc. for the EPA.

2. The smoke-spot number can be determined with ASTM Test Method D-2156 or with the 

Bacharach method. ASTM Test Method D-2156 is included in a tune-up kit that can be 

purchased from the Bacharach Company

3. Typical minimum oxygen levels for boilers at high firing rates are:

For natural gas: 0.5% - 3.0%

For liquid fuels: 2.0% - 4.0%