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Subpart ZZZZ—National Emissions Standards for Hazardous Air Pollutants for 

Stationary Reciprocating Internal Combustion Engines

What This Subpart Covers

§63.6580 What is the purpose of subpart ZZZZ?

Subpart ZZZZ establishes national emission limitations and operating limitations for 

hazardous air pollutants (HAP) emitted from stationary reciprocating internal combustion 

engines (RICE) located at major and area sources of HAP emissions. This subpart also 

establishes requirements to demonstrate initial and continuous compliance with the emission 

limitations and operating limitations.

§63.6585 Am I subject to this subpart?

You are subject to this subpart if you own or operate a stationary RICE at a major or area 

source of HAP emissions, except if the stationary RICE is being tested at a stationary RICE test 

cell/stand.

(a) A stationary RICE is any internal combustion engine which uses reciprocating motion 

to convert heat energy into mechanical work and which is not mobile. Stationary RICE differ 

from mobile RICE in that a stationary RICE is not a non-road engine as defined at 40 CFR 

1068.30, and is not used to propel a motor vehicle or a vehicle used solely for competition.

(b) A major source of HAP emissions is a plant site that emits or has the potential to emit 

any single HAP at a rate of 10 tons (9.07 megagrams) or more per year or any combination of 

HAP at a rate of 25 tons (22.68 megagrams) or more per year, except that for oil and gas 

production facilities, a major source of HAP emissions is determined for each surface site.

(c) An area source of HAP emissions is a source that is not a major source.

(d) If you are an owner or operator of an area source subject to this subpart, your status as 

an entity subject to a standard or other requirements under this subpart does not subject you to 

the obligation to obtain a permit under 40 CFR part 70 or 71, provided you are not required to 

obtain a permit under 40 CFR 70.3(a) or 40 CFR 71.3(a) for a reason other than your status as an 

area source under this subpart. Notwithstanding the previous sentence, you must continue to 

comply with the provisions of this subpart as applicable.

(e) If you are an owner or operator of a stationary RICE used for national security 

purposes, you may be eligible to request an exemption from the requirements of this subpart as 

described in 40 CFR part 1068, subpart C.
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(f) The emergency stationary RICE listed in paragraphs (f)(1) through (3) of this section 

are not subject to this subpart. The stationary RICE must meet the definition of an emergency

stationary RICE in §63.6675, which includes operating according to the provisions specified in 

§63.6640(f). 

(1) Existing residential emergency stationary RICE located at an area source of HAP 

emissions. 

(2) Existing commercial emergency stationary RICE located at an area source of HAP 

emissions.

(3) Existing institutional emergency stationary RICE located at an area source of HAP 

emissions.

§63.6590 What parts of my plant does this subpart cover?

This subpart applies to each affected source.

(a) Affected source. An affected source is any existing, new, or reconstructed stationary

RICE located at a major or area source of HAP emissions, excluding stationary RICE being 

tested at a stationary RICE test cell/stand.

(1) Existing stationary RICE.

(i) For stationary RICE with a site rating of more than 500 brake horsepower (HP) 

located at a major source of HAP emissions, a stationary RICE is existing if you commenced 

construction or reconstruction of the stationary RICE before December 19, 2002.

(ii) For stationary RICE with a site rating of less than or equal to 500 brake HP located at 

a major source of HAP emissions, a stationary RICE is existing if you commenced construction 

or reconstruction of the stationary RICE before June 12, 2006.

(iii) For stationary RICE located at an area source of HAP emissions, a stationary RICE 

is existing if you commenced construction or reconstruction of the stationary RICE before June 

12, 2006.

(iv) A change in ownership of an existing stationary RICE does not make that stationary

RICE a new or reconstructed stationary RICE.

(2) New stationary RICE. (i) A stationary RICE with a site rating of more than 500 brake 

HP located at a major source of HAP emissions is new if you commenced construction of the 

stationary RICE on or after December 19, 2002.
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(ii) A stationary RICE with a site rating of equal to or less than 500 brake HP located at a 

major source of HAP emissions is new if you commenced construction of the stationary RICE on 

or after June 12, 2006.

(iii) A stationary RICE located at an area source of HAP emissions is new if you 

commenced construction of the stationary RICE on or after June 12, 2006.

(3) Reconstructed stationary RICE. (i) A stationary RICE with a site rating of more than 

500 brake HP located at a major source of HAP emissions is reconstructed if you meet the 

definition of reconstruction in §63.2 and reconstruction is commenced on or after December 19, 

2002.

(ii) A stationary RICE with a site rating of equal to or less than 500 brake HP located at a 

major source of HAP emissions is reconstructed if you meet the definition of reconstruction in 

§63.2 and reconstruction is commenced on or after June 12, 2006.

(iii) A stationary RICE located at an area source of HAP emissions is reconstructed if you 

meet the definition of reconstruction in §63.2 and reconstruction is commenced on or after June 

12, 2006.

(b) Stationary RICE subject to limited requirements. (1) An affected source which meets 

either of the criteria in paragraphs (b)(1)(i) through (ii) of this section does not have to meet the 

requirements of this subpart and of subpart A of this part except for the initial notification 

requirements of §63.6645(f).

(i) The stationary RICE is a new or reconstructed emergency stationary RICE with a site 

rating of more than 500 brake HP located at a major source of HAP emissions.

(ii) The stationary RICE is a new or reconstructed limited use stationary RICE with a site 

rating of more than 500 brake HP located at a major source of HAP emissions.

(2) A new or reconstructed stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions which combusts landfill or digester gas equivalent to 

10 percent or more of the gross heat input on an annual basis must meet the initial notification 

requirements of §63.6645(f) and the requirements of §§63.6625(c), 63.6650(g), and 63.6655(c). 

These stationary RICE do not have to meet the emission limitations and operating limitations of 

this subpart. (3) The following stationary RICE do not have to meet the requirements of this 

subpart and of subpart A of this part, including initial notification requirements:
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(i) Existing spark ignition 2 stroke lean burn (2SLB) stationary RICE with a site rating of 

more than 500 brake HP located at a major source of HAP emissions;

(ii) Existing spark ignition 4 stroke lean burn (4SLB) stationary RICE with a site rating 

of more than 500 brake HP located at a major source of HAP emissions;

(iii) Existing emergency stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions;

(iv) Existing limited use stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions;

(v) Existing stationary RICE with a site rating of more than 500 brake HP located at a 

major source of HAP emissions that combusts landfill gas or digester gas equivalent to 10 

percent or more of the gross heat input on an annual basis; (c) Stationary RICE subject to 

Regulations under 40 CFR Part 60. An affected source that meets any of the criteria in 

paragraphs (c)(1) through (7) of this section must meet the requirements of this part by meeting 

the requirements of 40 CFR part 60 subpart IIII, for compression ignition engines or 40 CFR part 

60 subpart JJJJ, for spark ignition engines. No further requirements apply for such engines under 

this part.

(1) A new or reconstructed stationary RICE located at an area source;

(2) A new or reconstructed 2SLB stationary RICE with a site rating of less than or equal 

to 500 brake HP located at a major source of HAP emissions;

(3) A new or reconstructed 4SLB stationary RICE with a site rating of less than 250 

brake HP located at a major source of HAP emissions;

(4) A new or reconstructed spark ignition 4 stroke rich burn (4SRB) stationary RICE with 

a site rating of less than or equal to 500 brake HP located at a major source of HAP emissions;

(5) A new or reconstructed stationary RICE with a site rating of less than or equal to 500 

brake HP located at a major source of HAP emissions which combusts landfill or digester gas 

equivalent to 10 percent or more of the gross heat input on an annual basis;

(6) A new or reconstructed emergency or limited use stationary RICE with a site rating of 

less than or equal to 500 brake HP located at a major source of HAP emissions;

(7) A new or reconstructed compression ignition (CI) stationary RICE with a site rating 

of less than or equal to 500 brake HP located at a major source of HAP emissions.

§63.6595 When do I have to comply with this subpart?
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(a) Affected sources.

(1) If you have an existing stationary RICE, excluding existing non-emergency CI 

stationary RICE, with a site rating of more than 500 brake HP located at a major source of HAP 

emissions, you must comply with the applicable emission limitations, operating limitations and 

other requirements no later than June 15, 2007. If you have an existing non-emergency CI 

stationary RICE with a site rating of more than 500 brake HP located at a major source of HAP 

emissions, an existing stationary CI RICE with a site rating of less than or equal to 500 brake HP 

located at a major source of HAP emissions, or an existing stationary CI RICE located at an area 

source of HAP emissions, you must comply with the applicable emission limitations, operating 

limitations, and other requirements no later than May 3, 2013. If you have an existing stationary 

SI RICE with a site rating of less than or equal to 500 brake HP located at a major source of 

HAP emissions, or an existing stationary SI RICE located at an area source of HAP emissions, 

you must comply with the applicable emission limitations, operating limitations, and other 

requirements no later than October 19, 2013.

(2) If you start up your new or reconstructed stationary RICE with a site rating of more than 500 

brake HP located at a major source of HAP emissions before August 16, 2004, you must comply

with the applicable emission limitations and operating limitations in this subpart no later than 

August 16, 2004.

(3) If you start up your new or reconstructed stationary RICE with a site rating of more 

than 500 brake HP located at a major source of HAP emissions after August 16, 2004, you must 

comply with the applicable emission limitations and operating limitations in this subpart upon 

startup of your affected source.

(4) If you start up your new or reconstructed stationary RICE with a site rating of less 

than or equal to 500 brake HP located at a major source of HAP emissions before January 18, 

2008, you must comply with the applicable emission limitations and operating limitations in this 

subpart no later than January 18, 2008.

(5) If you start up your new or reconstructed stationary RICE with a site rating of less 

than or equal to 500 brake HP located at a major source of HAP emissions after January 18, 

2008, you must comply with the applicable emission limitations and operating limitations in this 

subpart upon startup of your affected source.
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(6) If you start up your new or reconstructed stationary RICE located at an area source of 

HAP emissions before January 18, 2008, you must comply with the applicable emission 

limitations and operating limitations in this subpart no later than January 18, 2008.

(7) If you start up your new or reconstructed stationary RICE located at an area source of 

HAP emissions after January 18, 2008, you must comply with the applicable emission 

limitations and operating limitations in this subpart upon startup of your affected source.

(b) Area sources that become major sources. If you have an area source that increases its 

emissions or its potential to emit such that it becomes a major source of HAP, the compliance 

dates in paragraphs (b)(1) and (2) of this section apply to you.

(1) Any stationary RICE for which construction or reconstruction is commenced after the 

date when your area source becomes a major source of HAP must be in compliance with this 

subpart upon startup of your affected source.

(2) Any stationary RICE for which construction or reconstruction is commenced before 

your area source becomes a major source of HAP must be in compliance with the provisions of 

this subpart that are applicable to RICE located at major sources within 3 years after your area 

source becomes a major source of HAP.

(c) If you own or operate an affected source, you must meet the applicable notification 

requirements in §63.6645 and in 40 CFR part 63, subpart A.

Emission and Operating Limitations

§63.6600 What emission limitations and operating limitations must I meet if I own or operate a 

stationary RICE with a site rating of more than 500 brake HP located at a major source of HAP 

emissions?

Compliance with the numerical emission limitations established in this subpart is based 

on the results of testing the average of three 1-hour runs using the testing requirements and 

procedures in §63.6620 and Table 4 to this subpart.

(a) If you own or operate an existing, new, or reconstructed spark ignition 4SRB 

stationary RICE with a site rating of more than 500 brake HP located at a major source of HAP 

emissions, you must comply with the emission limitations in Table 1a to this subpart and the 

operating limitations in Table 1b to this subpart which apply to you.

(b) If you own or operate a new or reconstructed 2SLB stationary RICE with a site rating 

of more than 500 brake HP located at major source of HAP emissions, a new or reconstructed 
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4SLB stationary RICE with a site rating of more than 500 brake HP located at major source of 

HAP emissions, or a new or reconstructed CI stationary RICE with a site rating of more than 500 

brake HP located at a major source of HAP emissions, you must comply with the emission 

limitations in Table 2a to this subpart and the operating limitations in Table 2b to this subpart 

which apply to you.

(c) If you own or operate any of the following stationary RICE with a site rating of more 

than 500 brake HP located at a major source of HAP emissions, you do not need to comply with 

the emission limitations in Tables 1a, 2a, 2c, and 2d to this subpart or operating limitations in 

Tables 1b and 2b to this subpart: an existing 2SLB stationary RICE; an existing 4SLB stationary

RICE; a stationary RICE that combusts landfill gas or digester gas equivalent to 10 percent or 

more of the gross heat input on an annual basis; an emergency stationary RICE; or a limited use 

stationary RICE.

(d) If you own or operate an existing non-emergency stationary CI RICE with a site 

rating of more than 500 brake HP located at a major source of HAP emissions, you must comply

with the emission limitations in Table 2c to this subpart and the operating limitations in Table 2b 

to this subpart which apply to you.

§63.6601 What emission limitations must I meet if I own or operate a new or reconstructed 

4SLB stationary RICE with a site rating of greater than or equal to 250 brake HP and less than or 

equal to 500 brake HP located at a major source of HAP emissions?

Compliance with the numerical emission limitations established in this subpart is based 

on the results of testing the average of three 1-hour runs using the testing requirements and 

procedures in §63.6620 and Table 4 to this subpart. If you own or operate a new or reconstructed 

4SLB stationary RICE with a site rating of greater than or equal to 250 and less than or equal to 

500 brake HP located at major source of HAP emissions manufactured on or after January 1, 

2008, you must comply with the emission limitations in Table 2a to this subpart and the 

operating limitations in Table 2b to this subpart which apply to you.

§63.6602 What emission limitations and other requirements must I meet if I own or operate an 

existing stationary RICE with a site rating of equal to or less than 500 brake HP located at a 

major source of HAP emissions?

If you own or operate an existing stationary RICE with a site rating of equal to or less 

than 500 brake HP located at a major source of HAP emissions, you must comply with the 
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emission limitations and other requirements in Table 2c to this subpart which apply to you. 

Compliance with the numerical emission limitations established in this subpart is based on the 

results of testing the average of three 1-hour runs using the testing requirements and procedures 

in §63.6620 and Table 4 to this subpart.

§63.6603 What emission limitations, operating limitations, and other requirements must I meet 

if I own or operate an existing stationary RICE located at an area source of HAP emissions?

Compliance with the numerical emission limitations established in this subpart is based on the 

results of testing the average of three 1-hour runs using the testing requirements and procedures 

in §63.6620 and Table 4 to this subpart.

(a) If you own or operate an existing stationary RICE located at an area source of HAP 

emissions, you must comply with the requirements in Table 2d to this subpart and the operating 

limitations in Table 1b and Table 2b to this subpart that apply to you.

(b) If you own or operate an existing stationary non-emergency CI RICE with a site 

rating of more than 300 HP located at an area source of HAP that meets either paragraph (b)(1) 

or (b)(2) of this section, you do not have to meet the numerical CO emission limitations specified 

in Table 2d of this subpart. Existing stationary non-emergency CI RICE with a site rating of

more than 300 HP located at an area source of HAP that meet either paragraph (b)(1) or (b)(2) of 

this section must meet the management practices that are shown for stationary non-emergency CI 

RICE with a site rating of less than or equal to 300 HP in Table 2d of this subpart.

(1) The area source is located in an area of Alaska that is not accessible by the Federal 

Aid Highway System (FAHS).

(2) The stationary RICE is located at an area source that meets paragraphs (b)(2)(i), 

(b)(2)(ii), and (b)(2)(iii) of this section.

(i) The only connection to the FAHS is through the Alaska Marine Highway System 

(AMHS), or the stationary RICE operation is within an isolated grid in Alaska that is not 

connected to the statewide electrical grid referred to as the Alaska Railbelt Grid.

(ii) At least 10 percent of the power generated by the stationary RICE on an annual basis 

is used for residential purposes.

(iii) The generating capacity of the area source is less than 12 megawatts, or the 

stationary RICE is used exclusively for backup power for renewable energy and is used less than 

500 hrs per year on a 10 year rolling average.
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(c) If you own or operate an existing non-emergency CI RICE with a site rating of more 

than 300 HP located at an area source of HAP emissions that is certified to the Tier 1 or Tier 2 

emission standards in Table 1 of 40 CFR 89.112 and that is subject to an enforceable state or 

local standard that requires the engine to be replaced no later than June 1, 2018, you may until 

January 1, 2015, or 12 years after the installation date of the engine (whichever is later), but not 

later than June 1, 2018, choose to comply with the management practices that are shown for 

stationary non-emergency CI RICE with a site rating of less than or equal to 300 HP in Table 2d 

of this subpart instead of the applicable emission limitations in Table 2d, operating limitations in 

Table 2b, and crankcase ventilation system requirements in §63.6625(g). You must comply with 

the emission limitations in Table 2d and operating limitations in Table 2b that apply for nonemergency CI RICE with a site rating of more than 300 HP located at an area source of HAP 

emissions by January 1, 2015, or 12 years after the installation date of the engine (whichever is 

later), but not later than June 1, 2018. You must also comply with the crankcase ventilation 

system requirements in §63.6625(g) by January 1, 2015, or 12 years after the installation date of 

the engine (whichever is later), but not later than June 1, 2018.

(d) If you own or operate an existing non-emergency CI RICE with a site rating of more 

than 300 HP located at an area source of HAP emissions that is certified to the Tier 3 (Tier 2 for 

engines above 560 kW) emission standards in Table 1 of 40 CFR 89.112, you may comply with 

the requirements under this part by meeting the requirements for Tier 3 engines (Tier 2 for 

engines above 560 kW) in 40 CFR part 60 subpart IIII instead of the emission limitations and 

other requirements that would otherwise apply under this part for existing non-emergency CI 

RICE with a site rating of more than 300 HP located at an area source of HAP emissions.

(e) An existing non-emergency SI 4SLB and 4SRB stationary RICE with a site rating of 

more than 500 HP located at area sources of HAP must meet the definition of remote stationary

RICE in §63.6675 on the initial compliance date for the engine, October 19, 2013, in order to be 

considered a remote stationary RICE under this subpart. Owners and operators of existing nonemergency SI 4SLB and 4SRB stationary RICE with a site rating of more than 500 HP located at 

area sources of HAP that meet the definition of remote stationary RICE in §63.6675 of this 

subpart as of October 19, 2013 must evaluate the status of their stationary RICE every 12 

months. Owners and operators must keep records of the initial and annual evaluation of the status 

of the engine. If the evaluation indicates that the stationary RICE no longer meets the definition 
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of remote stationary RICE in §63.6675 of this subpart, the owner or operator must comply with 

all of the requirements for existing non-emergency SI 4SLB and 4SRB stationary RICE with a 

site rating of more than 500 HP located at area sources of HAP that are not remote stationary

RICE within one year of the evaluation.

§63.6604 What fuel requirements must I meet if I own or operate an existing stationary CI 

RICE?

If you own or operate an existing non-emergency, non-black start CI stationary RICE with a site 

rating of more than 300 brake HP with a displacement of less than 30 liters per cylinder that uses 

diesel fuel, you must use diesel fuel that meets the requirements in 40 CFR 80.510(b) for 

nonroad diesel fuel. Existing non-emergency CI stationary RICE located in Guam, American 

Samoa, the Commonwealth of the Northern Mariana Islands, or at area sources in areas of 

Alaska that meet either §63.6603(b)(1) or §63.6603(b)(2) are exempt from the requirements of 

this section.

General Compliance Requirements

§63.6605 What are my general requirements for complying with this subpart?

(a) You must be in compliance with the emission limitations, operating limitations, and 

other requirements in this subpart that apply to you at all times.

(b) At all times you must operate and maintain any affected source, including associated 

air pollution control equipment and monitoring equipment, in a manner consistent with safety

and good air pollution control practices for minimizing emissions. The general duty to minimize 

emissions does not require you to make any further efforts to reduce emissions if levels required 

by this standard have been achieved. Determination of whether such operation and maintenance 

procedures are being used will be based on information available to the Administrator which 

may include, but is not limited to, monitoring results, review of operation and maintenance 

procedures, review of operation and maintenance records, and inspection of the source.

Testing and Initial Compliance Requirements

§63.6610 By what date must I conduct the initial performance tests or other initial compliance 

demonstrations if I own or operate a stationary RICE with a site rating of more than 500 brake 

HP located at a major source of HAP emissions?

If you own or operate a stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions you are subject to the requirements of this section.
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(a) You must conduct the initial performance test or other initial compliance 

demonstrations in Table 4 to this subpart that apply to you within 180 days after the compliance 

date that is specified for your stationary RICE in §63.6595 and according to the provisions in 

§63.7(a)(2).

(b) If you commenced construction or reconstruction between December 19, 2002 and 

June 15, 2004 and own or operate stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions, you must demonstrate initial compliance with either 

the proposed emission limitations or the promulgated emission limitations no later than February

10, 2005 or no later than 180 days after startup of the source, whichever is later, according to 

§63.7(a)(2)(ix).

(c) If you commenced construction or reconstruction between December 19, 2002 and 

June 15, 2004 and own or operate stationary RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions, and you chose to comply with the proposed 

emission limitations when demonstrating initial compliance, you must conduct a second 

performance test to demonstrate compliance with the promulgated emission limitations by

December 13, 2007 or after startup of the source, whichever is later, according to §63.7(a)(2)(ix).

(d) An owner or operator is not required to conduct an initial performance test on units 

for which a performance test has been previously conducted, but the test must meet all of the 

conditions described in paragraphs (d)(1) through (5) of this section.

(1) The test must have been conducted using the same methods specified in this subpart, 

and these methods must have been followed correctly.

(2) The test must not be older than 2 years.

(3) The test must be reviewed and accepted by the Administrator.

(4) Either no process or equipment changes must have been made since the test was 

performed, or the owner or operator must be able to demonstrate that the results of the 

performance test, with or without adjustments, reliably demonstrate compliance despite process 

or equipment changes.

(5) The test must be conducted at any load condition within plus or minus 10 percent of 

100 percent load.

§63.6611 By what date must I conduct the initial performance tests or other initial compliance 

demonstrations if I own or operate a new or reconstructed 4SLB SI stationary RICE with a site 
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rating of greater than or equal to 250 and less than or equal to 500 brake HP located at a major 

source of HAP emissions?

If you own or operate a new or reconstructed 4SLB stationary RICE with a site rating of 

greater than or equal to 250 and less than or equal to 500 brake HP located at a major source of 

HAP emissions, you must conduct an initial performance test within 240 days after the 

compliance date that is specified for your stationary RICE in §63.6595 and according to the 

provisions specified in Table 4 to this subpart, as appropriate.

§63.6612 By what date must I conduct the initial performance tests or other initial compliance 

demonstrations if I own or operate an existing stationary RICE with a site rating of less than or 

equal to 500 brake HP located at a major source of HAP emissions or an existing stationary

RICE located at an area source of HAP emissions?

If you own or operate an existing stationary RICE with a site rating of less than or equal 

to 500 brake HP located at a major source of HAP emissions or an existing stationary RICE 

located at an area source of HAP emissions you are subject to the requirements of this section.

(a) You must conduct any initial performance test or other initial compliance 

demonstration according to Tables 4 and 5 to this subpart that apply to you within 180 days after 

the compliance date that is specified for your stationary RICE in §63.6595 and according to the 

provisions in §63.7(a)(2).

(b) An owner or operator is not required to conduct an initial performance test on a unit 

for which a performance test has been previously conducted, but the test must meet all of the 

conditions described in paragraphs (b)(1) through (4) of this section.

(1) The test must have been conducted using the same methods specified in this subpart, 

and these methods must have been followed correctly.

(2) The test must not be older than 2 years.

(3) The test must be reviewed and accepted by the Administrator.

(4) Either no process or equipment changes must have been made since the test was 

performed, or the owner or operator must be able to demonstrate that the results of the 

performance test, with or without adjustments, reliably demonstrate compliance despite process 

or equipment changes.

§63.6615 When must I conduct subsequent performance tests?
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If you must comply with the emission limitations and operating limitations, you must 

conduct subsequent performance tests as specified in Table 3 of this subpart.

§63.6620 What performance tests and other procedures must I use?

(a) You must conduct each performance test in Tables 3 and 4 of this subpart that applies 

to you.

(b) Each performance test must be conducted according to the requirements that this 

subpart specifies in Table 4 to this subpart. If you own or operate a non-operational stationary

RICE that is subject to performance testing, you do not need to start up the engine solely to 

conduct the performance test. Owners and operators of a non-operational engine can conduct the 

performance test when the engine is started up again.

The test must be conducted at any load condition within plus or minus 10 percent of 100 

percent load for the stationary RICE listed in paragraphs (b)(1) through (4) of this section.

(1) Non-emergency 4SRB stationary RICE with a site rating of greater than 500 brake 

HP located at a major source of HAP emissions.

(2) New non-emergency 4SLB stationary RICE with a site rating of greater than or equal 

to 250 brake HP located at a major source of HAP emissions.

(3) New non-emergency 2SLB stationary RICE with a site rating of greater than 500 

brake HP located at a major source of HAP emissions.

(4) New non-emergency CI stationary RICE with a site rating of greater than 500 brake 

HP located at a major source of HAP emissions. 

(c) [Reserved]

(d) You must conduct three separate test runs for each performance test required in this 

section, as specified in §63.7(e)(3). Each test run must last at least 1 hour.

(e)(1) You must use Equation 1 of this section to determine compliance with the percent 

reduction requirement:

Where:

Ci= concentration of CO, THC, or formaldehyde at the control device inlet,
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Co= concentration of CO, THC, or formaldehyde at the control device outlet, and

R = percent reduction of CO, THC, or formaldehyde emissions.

(2) You must normalize the carbon monoxide (CO), total hydrocarbons (THC), or 

formaldehyde concentrations at the inlet and outlet of the control device to a dry basis and to 15 

percent oxygen, or an equivalent percent carbon dioxide (CO2). If pollutant concentrations are to 

be corrected to 15 percent oxygen and CO2 concentration is measured in lieu of oxygen 

concentration measurement, a CO2 correction factor is needed. Calculate the CO2 correction 

factor as described in paragraphs (e)(2)(i) through (iii) of this section.

(i) Calculate the fuel-specific Fo value for the fuel burned during the test using values 

obtained from Method 19, Section 5.2, and the following equation:

Where:

Fo= Fuel factor based on the ratio of oxygen volume to the ultimate CO2 volume produced by the 

fuel at zero percent excess air.

0.209 = Fraction of air that is oxygen, percent/100.

Fd= Ratio of the volume of dry effluent gas to the gross calorific value of the fuel from Method 

19, dsm3/J (dscf/106 Btu).

Fc= Ratio of the volume of CO2 produced to the gross calorific value of the fuel from Method 19, 

dsm3/J (dscf/106 Btu).

(ii) Calculate the CO2 correction factor for correcting measurement data to 15 percent 

oxygen, as follows:

Where:

Xco2= CO2 correction factor, percent.

5.9 = 20.9 percent O2−15 percent O2, the defined O2 correction value, percent.
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(iii) Calculate the CO, THC, and formaldehyde gas concentrations adjusted to 15 percent 

O2 using CO2 as follows:

Where:

%CO2= Measured CO2 concentration measured, dry basis, percent.

(f) If you comply with the emission limitation to reduce CO and you are not using an 

oxidation catalyst, if you comply with the emission limitation to reduce formaldehyde and you 

are not using NSCR, or if you comply with the emission limitation to limit the concentration of 

formaldehyde in the stationary RICE exhaust and you are not using an oxidation catalyst or 

NSCR, you must petition the Administrator for operating limitations to be established during the 

initial performance test and continuously monitored thereafter; or for approval of no operating 

limitations. You must not conduct the initial performance test until after the petition has been 

approved by the Administrator.

(g) If you petition the Administrator for approval of operating limitations, your petition 

must include the information described in paragraphs (g)(1) through (5) of this section.

(1) Identification of the specific parameters you propose to use as operating limitations;

(2) A discussion of the relationship between these parameters and HAP emissions, 

identifying how HAP emissions change with changes in these parameters, and how limitations 

on these parameters will serve to limit HAP emissions;

(3) A discussion of how you will establish the upper and/or lower values for these 

parameters which will establish the limits on these parameters in the operating limitations;

(4) A discussion identifying the methods you will use to measure and the instruments you 

will use to monitor these parameters, as well as the relative accuracy and precision of these 

methods and instruments; and

(5) A discussion identifying the frequency and methods for recalibrating the instruments 

you will use for monitoring these parameters.
16

(h) If you petition the Administrator for approval of no operating limitations, your 

petition must include the information described in paragraphs (h)(1) through (7) of this section.

(1) Identification of the parameters associated with operation of the stationary RICE and 

any emission control device which could change intentionally (e.g., operator adjustment, 

automatic controller adjustment, etc.) or unintentionally (e.g., wear and tear, error, etc.) on a 

routine basis or over time;

(2) A discussion of the relationship, if any, between changes in the parameters and 

changes in HAP emissions;

(3) For the parameters which could change in such a way as to increase HAP emissions, a 

discussion of whether establishing limitations on the parameters would serve to limit HAP 

emissions;

(4) For the parameters which could change in such a way as to increase HAP emissions, a 

discussion of how you could establish upper and/or lower values for the parameters which would 

establish limits on the parameters in operating limitations;

(5) For the parameters, a discussion identifying the methods you could use to measure 

them and the instruments you could use to monitor them, as well as the relative accuracy and 

precision of the methods and instruments;

(6) For the parameters, a discussion identifying the frequency and methods for 

recalibrating the instruments you could use to monitor them; and

(7) A discussion of why, from your point of view, it is infeasible or unreasonable to adopt 

the parameters as operating limitations.

(i) The engine percent load during a performance test must be determined by

documenting the calculations, assumptions, and measurement devices used to measure or 

estimate the percent load in a specific application. A written report of the average percent load 

determination must be included in the notification of compliance status. The following 

information must be included in the written report: the engine model number, the engine 

manufacturer, the year of purchase, the manufacturer's site-rated brake horsepower, the ambient 

temperature, pressure, and humidity during the performance test, and all assumptions that were 

made to estimate or calculate percent load during the performance test must be clearly explained. 

If measurement devices such as flow meters, kilowatt meters, beta analyzers, stain gauges, etc. 
17

are used, the model number of the measurement device, and an estimate of its accurate in 

percentage of true value must be provided.

§63.6625 What are my monitoring, installation, collection, operation, and maintenance 

requirements?

(a) If you elect to install a CEMS as specified in Table 5 of this subpart, you must install, 

operate, and maintain a CEMS to monitor CO and either oxygen or CO2 according to the 

requirements in paragraphs (a)(1) through (4) of this section. If you are meeting a requirement to 

reduce CO emissions, the CEMS must be installed at both the inlet and outlet of the control 

device. If you are meeting a requirement to limit the concentration of CO, the CEMS must be 

installed at the outlet of the control device.

(1) Each CEMS must be installed, operated, and maintained according to the applicable 

performance specifications of 40 CFR part 60, appendix B.

(2) You must conduct an initial performance evaluation and an annual relative accuracy

test audit (RATA) of each CEMS according to the requirements in §63.8 and according to the 

applicable performance specifications of 40 CFR part 60, appendix B as well as daily and 

periodic data quality checks in accordance with 40 CFR part 60, appendix F, procedure 1.

(3) As specified in §63.8(c)(4)(ii), each CEMS must complete a minimum of one cycle of 

operation (sampling, analyzing, and data recording) for each successive 15-minute period. You 

must have at least two data points, with each representing a different 15-minute period, to have a 

valid hour of data.

(4) The CEMS data must be reduced as specified in §63.8(g)(2) and recorded in parts per 

million or parts per billion (as appropriate for the applicable limitation) at 15 percent oxygen or 

the equivalent CO2concentration.

(b) If you are required to install a continuous parameter monitoring system (CPMS) as 

specified in Table 5 of this subpart, you must install, operate, and maintain each CPMS 

according to the requirements in paragraphs (b)(1) through (6) of this section. For an affected 

source that is complying with the emission limitations and operating limitations on March 9, 

2011, the requirements in paragraph (b) of this section are applicable September 6, 2011.

(1) You must prepare a site-specific monitoring plan that addresses the monitoring 

system design, data collection, and the quality assurance and quality control elements outlined in 

paragraphs (b)(1)(i) through (v) of this section and in §63.8(d). As specified in §63.8(f)(4), you 
18

may request approval of monitoring system quality assurance and quality control procedures 

alternative to those specified in paragraphs (b)(1) through (5) of this section in your site-specific 

monitoring plan.

(i) The performance criteria and design specifications for the monitoring system 

equipment, including the sample interface, detector signal analyzer, and data acquisition and 

calculations;

(ii) Sampling interface ( e.g., thermocouple) location such that the monitoring system will 

provide representative measurements;

(iii) Equipment performance evaluations, system accuracy audits, or other audit 

procedures;

(iv) Ongoing operation and maintenance procedures in accordance with provisions in 

§63.8(c)(1) and (c)(3); and

(v) Ongoing reporting and recordkeeping procedures in accordance with provisions in 

§63.10(c), (e)(1), and (e)(2)(i).

(2) You must install, operate, and maintain each CPMS in continuous operation 

according to the procedures in your site-specific monitoring plan.

(3) The CPMS must collect data at least once every 15 minutes (see also §63.6635).

(4) For a CPMS for measuring temperature range, the temperature sensor must have a 

minimum tolerance of 2.8 degrees Celsius (5 degrees Fahrenheit) or 1 percent of the 

measurement range, whichever is larger.

(5) You must conduct the CPMS equipment performance evaluation, system accuracy

audits, or other audit procedures specified in your site-specific monitoring plan at least annually.

(6) You must conduct a performance evaluation of each CPMS in accordance with your 

site-specific monitoring plan.

(c) If you are operating a new or reconstructed stationary RICE which fires landfill gas or 

digester gas equivalent to 10 percent or more of the gross heat input on an annual basis, you must 

monitor and record your fuel usage daily with separate fuel meters to measure the volumetric 

flow rate of each fuel. In addition, you must operate your stationary RICE in a manner which 

reasonably minimizes HAP emissions.

(d) If you are operating a new or reconstructed emergency 4SLB stationary RICE with a 

site rating of greater than or equal to 250 and less than or equal to 500 brake HP located at a 
19

major source of HAP emissions, you must install a non-resettable hour meter prior to the startup 

of the engine.

(e) If you own or operate any of the following stationary RICE, you must operate and 

maintain the stationary RICE and after-treatment control device (if any) according to the 

manufacturer's emission-related written instructions or develop your own maintenance plan 

which must provide to the extent practicable for the maintenance and operation of the engine in a 

manner consistent with good air pollution control practice for minimizing emissions:

(1) An existing stationary RICE with a site rating of less than 100 HP located at a major 

source of HAP emissions;

(2) An existing emergency or black start stationary RICE with a site rating of less than or 

equal to 500 HP located at a major source of HAP emissions;

(3) An existing emergency or black start stationary RICE located at an area source of 

HAP emissions;

(4) An existing non-emergency, non-black start stationary CI RICE with a site rating less 

than or equal to 300 HP located at an area source of HAP emissions;

(5) An existing non-emergency, non-black start 2SLB stationary RICE located at an area 

source of HAP emissions;

(6) An existing non-emergency, non-black start stationary RICE located at an area source 

of HAP emissions which combusts landfill or digester gas equivalent to 10 percent or more of 

the gross heat input on an annual basis ;

(7) An existing non-emergency, non-black start 4SLB stationary RICE with a site rating 

less than or equal to 500 HP located at an area source of HAP emissions;

(8) An existing non-emergency, non-black start 4SRB stationary RICE with a site rating 

less than or equal to 500 HP located at an area source of HAP emissions;

(9) An existing, non-emergency, non-black start 4SLB stationary RICE with a site rating 

greater than 500 HP located at an area source of HAP emissions that is operated 24 hours or less 

per calendar year; and

(10) An existing, non-emergency, non-black start 4SRB stationary RICE with a site 

rating greater than 500 HP located at an area source of HAP emissions that is operated 24 hours 

or less per calendar year.
20

(f) If you own or operate an existing emergency stationary RICE with a site rating of less 

than or equal to 500 brake HP located at a major source of HAP emissions or an existing 

emergency stationary RICE located at an area source of HAP emissions, you must install a nonresettable hour meter if one is not already installed.

(g) If you own or operate an existing non-emergency, non-black start CI engine greater 

than or equal to 300 HP that is not equipped with a closed crankcase ventilation system, you 

must comply with either paragraph (g)(1) or paragraph (g)(2) of this section. Owners and 

operators must follow the manufacturer's specified maintenance requirements for operating and 

maintaining the open or closed crankcase ventilation systems and replacing the crankcase filters, 

or can request the Administrator to approve different maintenance requirements that are as 

protective as manufacturer requirements. Existing CI engines located at area sources in areas of 

Alaska that meet either §63.6603(b)(1) or §63.6603(b)(2) do not have to meet the requirements 

of paragraph (g) of this section.

(1) Install a closed crankcase ventilation system that prevents crankcase emissions from 

being emitted to the atmosphere, or

(2) Install an open crankcase filtration emission control system that reduces emissions 

from the crankcase by filtering the exhaust stream to remove oil mist, particulates, and metals.

(h) If you operate a new, reconstructed, or existing stationary engine, you must minimize 

the engine's time spent at idle during startup and minimize the engine's startup time to a period 

needed for appropriate and safe loading of the engine, not to exceed 30 minutes, after which time 

the emission standards applicable to all times other than startup in Tables 1a, 2a, 2c, and 2d to 

this subpart apply.

(i) If you own or operate a stationary CI engine that is subject to the work, operation or 

management practices in items 1 or 2 of Table 2c to this subpart or in items 1 or 4 of Table 2d to 

this subpart, you have the option of utilizing an oil analysis program in order to extend the 

specified oil change requirement in Tables 2c and 2d to this subpart. The oil analysis must be 

performed at the same frequency specified for changing the oil in Table 2c or 2d to this subpart. 

The analysis program must at a minimum analyze the following three parameters: Total Base 

Number, viscosity, and percent water content. The condemning limits for these parameters are as 

follows: Total Base Number is less than 30 percent of the Total Base Number of the oil when 

new; viscosity of the oil has changed by more than 20 percent from the viscosity of the oil when 
21

new; or percent water content (by volume) is greater than 0.5. If all of these condemning limits 

are not exceeded, the engine owner or operator is not required to change the oil. If any of the 

limits are exceeded, the engine owner or operator must change the oil within 2 days of receiving 

the results of the analysis; if the engine is not in operation when the results of the analysis are 

received, the engine owner or operator must change the oil within 2 days or before commencing 

operation, whichever is later. The owner or operator must keep records of the parameters that are 

analyzed as part of the program, the results of the analysis, and the oil changes for the engine. 

The analysis program must be part of the maintenance plan for the engine.

(j) If you own or operate a stationary SI engine that is subject to the work, operation or 

management practices in items 6, 7, or 8 of Table 2c to this subpart or in items 5, 6, 7, 9, or 11 of 

Table 2d to this subpart, you have the option of utilizing an oil analysis program in order to 

extend the specified oil change requirement in Tables 2c and 2d to this subpart. The oil analysis 

must be performed at the same frequency specified for changing the oil in Table 2c or 2d to this 

subpart. The analysis program must at a minimum analyze the following three parameters: Total 

Acid Number, viscosity, and percent water content. The condemning limits for these parameters 

are as follows: Total Acid Number increases by more than 3.0 milligrams of potassium 

hydroxide (KOH) per gram from Total Acid Number of the oil when new; viscosity of the oil has 

changed by more than 20 percent from the viscosity of the oil when new; or percent water 

content (by volume) is greater than 0.5. If all of these condemning limits are not exceeded, the 

engine owner or operator is not required to change the oil. If any of the limits are exceeded, the 

engine owner or operator must change the oil within 2 days of receiving the results of the 

analysis; if the engine is not in operation when the results of the analysis are received, the engine 

owner or operator must change the oil within 2 days or before commencing operation, whichever 

is later. The owner or operator must keep records of the parameters that are analyzed as part of 

the program, the results of the analysis, and the oil changes for the engine. The analysis program 

must be part of the maintenance plan for the engine.

§63.6630 How do I demonstrate initial compliance with the emission limitations, operating 

limitations, and other requirements?

(a) You must demonstrate initial compliance with each emission limitation, operating 

limitation, and other requirements that applies to you according to Table 5 of this subpart.
22

(b) During the initial performance test, you must establish each operating limitation in 

Tables 1b and 2b of this subpart that applies to you.

(c) You must submit the Notification of Compliance Status containing the results of the 

initial compliance demonstration according to the requirements in §63.6645.

(d) Non-emergency 4SRB stationary RICE complying with the requirement to reduce 

formaldehyde emissions by 76 percent or more can demonstrate initial compliance with the 

formaldehyde emission limit by testing for THC instead of formaldehyde. The testing must be 

conducted according to the requirements in Table 4 of this subpart. The average reduction of 

emissions of THC determined from the performance test must be equal to or greater than 30 

percent.

(e) The initial compliance demonstration required for existing non-emergency 4SLB and 

4SRB stationary RICE with a site rating of more than 500 HP located at an area source of HAP 

that are not remote stationary RICE and that are operated more than 24 hours per calendar year 

must be conducted according to the following requirements:

(1) The compliance demonstration must consist of at least three test runs.

(2) Each test run must be of at least 15 minute duration, except that each test conducted 

using the method in appendix A to this subpart must consist of at least one measurement cycle 

and include at least 2 minutes of test data phase measurement.

(3) If you are demonstrating compliance with the CO concentration or CO percent 

reduction requirement, you must measure CO emissions using one of the CO measurement 

methods specified in Table 4 of this subpart, or using appendix A to this subpart.

(4) If you are demonstrating compliance with the THC percent reduction requirement, 

you must measure THC emissions using Method 25A of 40 CFR part 60, appendix A.

(5) You must measure O2 using one of the O2 measurement methods specified in Table 4 

of this subpart. Measurements to determine O2 concentration must be made at the same time as 

the measurements for CO or THC concentration.

(6) If you are demonstrating compliance with the CO or THC percent reduction 

requirement, you must measure CO or THC emissions and O2 emissions simultaneously at the 

inlet and outlet of the control device.

Continuous Compliance Requirements

§63.6635 How do I monitor and collect data to demonstrate continuous compliance?
23

(a) If you must comply with emission and operating limitations, you must monitor and 

collect data according to this section.

(b) Except for monitor malfunctions, associated repairs, required performance 

evaluations, and required quality assurance or control activities, you must monitor continuously

at all times that the stationary RICE is operating. A monitoring malfunction is any sudden, 

infrequent, not reasonably preventable failure of the monitoring to provide valid data. 

Monitoring failures that are caused in part by poor maintenance or careless operation are not 

malfunctions.

(c) You may not use data recorded during monitoring malfunctions, associated repairs, 

and required quality assurance or control activities in data averages and calculations used to 

report emission or operating levels. You must, however, use all the valid data collected during all 

other periods.

§63.6640 How do I demonstrate continuous compliance with the emission limitations, operating 

limitations, and other requirements?

(a) You must demonstrate continuous compliance with each emission limitation,

operating limitation, and other requirements in Tables 1a and 1b, Tables 2a and 2b, Table 2c, and 

Table 2d to this subpart that apply to you according to methods specified in Table 6 to this 

subpart.

(b) You must report each instance in which you did not meet each emission limitation or 

operating limitation in Tables 1a and 1b, Tables 2a and 2b, Table 2c, and Table 2d to this subpart 

that apply to you. These instances are deviations from the emission and operating limitations in 

this subpart. These deviations must be reported according to the requirements in §63.6650. If you 

change your catalyst, you must reestablish the values of the operating parameters measured 

during the initial performance test. When you reestablish the values of your operating 

parameters, you must also conduct a performance test to demonstrate that you are meeting the 

required emission limitation applicable to your stationary RICE.

(c) The annual compliance demonstration required for existing non-emergency 4SLB and 

4SRB stationary RICE with a site rating of more than 500 HP located at an area source of HAP 

that are not remote stationary RICE and that are operated more than 24 hours per calendar year 

must be conducted according to the following requirements:

(1) The compliance demonstration must consist of at least one test run.
24

(2) Each test run must be of at least 15 minute duration, except that each test conducted 

using the method in appendix A to this subpart must consist of at least one measurement cycle 

and include at least 2 minutes of test data phase measurement.

(3) If you are demonstrating compliance with the CO concentration or CO percent 

reduction requirement, you must measure CO emissions using one of the CO measurement 

methods specified in Table 4 of this subpart, or using appendix A to this subpart.

(4) If you are demonstrating compliance with the THC percent reduction requirement, 

you must measure THC emissions using Method 25A of 40 CFR part 60, appendix A.

(5) You must measure O2 using one of the O2 measurement methods specified in Table 4 

of this subpart. Measurements to determine O2 concentration must be made at the same time as 

the measurements for CO or THC concentration.

(6) If you are demonstrating compliance with the CO or THC percent reduction 

requirement, you must measure CO or THC emissions and O2 emissions simultaneously at the 

inlet and outlet of the control device.

(7) If the results of the annual compliance demonstration show that the emissions exceed 

the levels specified in Table 6 of this subpart, the stationary RICE must be shut down as soon as 

safely possible, and appropriate corrective action must be taken (e.g., repairs, catalyst cleaning, 

catalyst replacement). The stationary RICE must be retested within 7 days of being restarted and 

the emissions must meet the levels specified in Table 6 of this subpart. If the retest shows that 

the emissions continue to exceed the specified levels, the stationary RICE must again be shut 

down as soon as safely possible, and the stationary RICE may not operate, except for purposes of 

startup and testing, until the owner/operator demonstrates through testing that the emissions do 

not exceed the levels specified in Table 6 of this subpart.

(d) For new, reconstructed, and rebuilt stationary RICE, deviations from the emission or 

operating limitations that occur during the first 200 hours of operation from engine startup 

(engine burn-in period) are not violations. Rebuilt stationary RICE means a stationary RICE that 

has been rebuilt as that term is defined in 40 CFR 94.11(a).

(e) You must also report each instance in which you did not meet the requirements in 

Table 8 to this subpart that apply to you. If you own or operate a new or reconstructed stationary

RICE with a site rating of less than or equal to 500 brake HP located at a major source of HAP 

emissions (except new or reconstructed 4SLB engines greater than or equal to 250 and less than 
25

or equal to 500 brake HP), a new or reconstructed stationary RICE located at an area source of 

HAP emissions, or any of the following RICE with a site rating of more than 500 brake HP 

located at a major source of HAP emissions, you do not need to comply with the requirements in 

Table 8 to this subpart: An existing 2SLB stationary RICE, an existing 4SLB stationary RICE, 

an existing emergency stationary RICE, an existing limited use stationary RICE, or an existing 

stationary RICE which fires landfill gas or digester gas equivalent to 10 percent or more of the 

gross heat input on an annual basis. If you own or operate any of the following RICE with a site 

rating of more than 500 brake HP located at a major source of HAP emissions, you do not need 

to comply with the requirements in Table 8 to this subpart, except for the initial notification 

requirements: a new or reconstructed stationary RICE that combusts landfill gas or digester gas 

equivalent to 10 percent or more of the gross heat input on an annual basis, a new or 

reconstructed emergency stationary RICE, or a new or reconstructed limited use stationary

RICE.

(f) If you own or operate an emergency stationary RICE, you must operate the emergency

stationary RICE according to the requirements in paragraphs (f)(1) through (4) of this section. In 

order for the engine to be considered an emergency stationary RICE under this subpart, any

operation other than emergency operation, maintenance and testing, emergency demand 

response, and operation in non-emergency situations for 50 hours per year, as described in 

paragraphs (f)(1) through (4) of this section, is prohibited. If you do not operate the engine

according to the requirements in paragraphs (f)(1) through (4) of this section, the engine will not 

be considered an emergency engine under this subpart and must meet all requirements for nonemergency engines. An engine that exceeds the calendar year limitations on non-emergency

operation will be considered a non-emergency engine and subject to the requirements for nonemergency engines for the remaining life of the engine.

(1) There is no time limit on the use of emergency stationary RICE in emergency

situations.

(2) You may operate your emergency stationary RICE for any combination of the 

purposes specified in paragraphs (f)(2)(i) through (iii) of this section for a maximum of 100 

hours per calendar year. Any operation for non-emergency situations as allowed by paragraphs 

(f)(3) and (4) of this section counts as part of the 100 hours per calendar year allowed by this 

paragraph (f)(2).
26

(i) Emergency stationary RICE may be operated for maintenance checks and readiness 

testing, provided that the tests are recommended by federal, state or local government, the 

manufacturer, the vendor, the regional transmission authority or equivalent balancing authority 

and transmission operator, or the insurance company associated with the engine. The owner or 

operator may petition the Administrator for approval of additional hours to be used for 

maintenance checks and readiness testing, but a petition is not required if the owner or operator 

maintains records indicating that federal, state, or local standards require maintenance and testing 

of emergency RICE beyond 100 hours per calendar year.

(ii) Emergency stationary RICE may be operated for emergency demand response for 

periods in which the regional transmission authority or equivalent balancing authority and 

transmission operator has declared an Energy Emergency Alert Level 2 (EEA Level 2) as 

defined in the North American Electric Reliability Corporation Reliability Standard EOP-002-3, 

Capacity and Energy Emergencies. 

(iii) Emergency stationary RICE may be operated for periods where there is a deviation 

of voltage or frequency of 5 percent or greater below standard voltage or frequency.

(3) Emergency stationary RICE located at major sources of HAP may be operated for up 

to 50 hours per calendar year in non-emergency situations. The 50 hours of operation in nonemergency situations are counted as part of the 100 hours per calendar year for maintenance and 

testing and emergency demand response provided in paragraph (f)(2) of this section. The 50 

hours per year for non-emergency situations cannot be used for peak shaving or non-emergency

demand response, or to generate income for a facility to supply power to an electric grid or 

otherwise supply power as part of a financial arrangement with another entity. 

(4) Existing emergency stationary RICE located at area sources of HAP may be operated 

for up to 50 hours per calendar year in non-emergency situations. The 50 hours of operation in 

non-emergency situations are counted as part of the 100 hours per calendar year for maintenance 

and testing and emergency demand response provided in paragraph (f)(2) of this section. 

(i) Prior to April 16, 2017, the 50 hours per year for non-emergency situations can be 

used for peak shaving or non-emergency demand response to generate income for a facility, or to 

otherwise supply power as part of a financial arrangement with another entity if engines is 

operated as part of a peak shaving (load management program) with the local distribution system 
27

operator and the power is provided only to the facility itself or to support the local distribution 

system.

(ii) On or after April 16, 2017, the 50 hours per year for non-emergency situations cannot 

be used for peak shaving or non-emergency demand response, or to otherwise supply power as 

part of a financial arrangement with another entity.

Notifications, Reports, and Records

§63.6645 What notifications must I submit and when?

(a) You must submit all of the notifications in §§63.7(b) and (c), 63.8(e), (f)(4) and (f)(6), 

63.9(b) through (e), and (g) and (h) that apply to you by the dates specified if you own or operate 

any of the following;

(1) An existing stationary RICE with a site rating of less than or equal to 500 brake HP 

located at a major source of HAP emissions.

(2) An existing stationary RICE located at an area source of HAP emissions.

(3) A stationary RICE with a site rating of more than 500 brake HP located at a major 

source of HAP emissions.

(4) A new or reconstructed 4SLB stationary RICE with a site rating of greater than or 

equal to 250 HP located at a major source of HAP emissions.

(5) This requirement does not apply if you own or operate an existing stationary RICE 

less than 100 HP, an existing stationary emergency RICE, or an existing stationary RICE that is 

not subject to any numerical emission standards.

(b) As specified in §63.9(b)(2), if you start up your stationary RICE with a site rating of 

more than 500 brake HP located at a major source of HAP emissions before the effective date of 

this subpart, you must submit an Initial Notification not later than December 13, 2004.

(c) If you start up your new or reconstructed stationary RICE with a site rating of more 

than 500 brake HP located at a major source of HAP emissions on or after August 16, 2004, you 

must submit an Initial Notification not later than 120 days after you become subject to this 

subpart.

(d) As specified in §63.9(b)(2), if you start up your stationary RICE with a site rating of 

equal to or less than 500 brake HP located at a major source of HAP emissions before the 
28

effective date of this subpart and you are required to submit an initial notification, you must 

submit an Initial Notification not later than July 16, 2008.

(e) If you start up your new or reconstructed stationary RICE with a site rating of equal to 

or less than 500 brake HP located at a major source of HAP emissions on or after March 18, 

2008 and you are required to submit an initial notification, you must submit an Initial 

Notification not later than 120 days after you become subject to this subpart.

(f) If you are required to submit an Initial Notification but are otherwise not affected by

the requirements of this subpart, in accordance with §63.6590(b), your notification should 

include the information in §63.9(b)(2)(i) through (v), and a statement that your stationary RICE 

has no additional requirements and explain the basis of the exclusion (for example, that it 

operates exclusively as an emergency stationary RICE if it has a site rating of more than 500 

brake HP located at a major source of HAP emissions).

(g) If you are required to conduct a performance test, you must submit a Notification of 

Intent to conduct a performance test at least 60 days before the performance test is scheduled to 

begin as required in §63.7(b)(1).

(h) If you are required to conduct a performance test or other initial compliance 

demonstration as specified in Tables 4 and 5 to this subpart, you must submit a Notification of 

Compliance Status according to §63.9(h)(2)(ii).

(1) For each initial compliance demonstration required in Table 5 to this subpart that does 

not include a performance test, you must submit the Notification of Compliance Status before the 

close of business on the 30th day following the completion of the initial compliance 

demonstration.

(2) For each initial compliance demonstration required in Table 5 to this subpart that 

includes a performance test conducted according to the requirements in Table 3 to this subpart, 

you must submit the Notification of Compliance Status, including the performance test results, 

before the close of business on the 60th day following the completion of the performance test 

according to §63.10(d)(2).

(i) If you own or operate an existing non-emergency CI RICE with a site rating of more 

than 300 HP located at an area source of HAP emissions that is certified to the Tier 1 or Tier 2 

emission standards in Table 1 of 40 CFR 89.112 and subject to an enforceable state or local 

standard requiring engine replacement and you intend to meet management practices rather than 
29

emission limits, as specified in §63.6603(c), you must submit a notification by March 3, 2013, 

stating that you intend to use the provision in §63.6603(c) and identifying the state or local 

regulation that the engine is subject to.

§63.6650 What reports must I submit and when?

(a) You must submit each report in Table 7 of this subpart that applies to you.

(b) Unless the Administrator has approved a different schedule for submission of reports 

under §63.10(a), you must submit each report by the date in Table 7 of this subpart and 

according to the requirements in paragraphs (b)(1) through (b)(9) of this section.

(1) For semiannual Compliance reports, the first Compliance report must cover the period 

beginning on the compliance date that is specified for your affected source in §63.6595 and 

ending on June 30 or December 31, whichever date is the first date following the end of the first 

calendar half after the compliance date that is specified for your source in §63.6595.

(2) For semiannual Compliance reports, the first Compliance report must be postmarked 

or delivered no later than July 31 or January 31, whichever date follows the end of the first

calendar half after the compliance date that is specified for your affected source in §63.6595.

(3) For semiannual Compliance reports, each subsequent Compliance report must cover 

the semiannual reporting period from January 1 through June 30 or the semiannual reporting 

period from July 1 through December 31.

(4) For semiannual Compliance reports, each subsequent Compliance report must be 

postmarked or delivered no later than July 31 or January 31, whichever date is the first date 

following the end of the semiannual reporting period.

(5) For each stationary RICE that is subject to permitting regulations pursuant to 40 CFR 

part 70 or 71, and if the permitting authority has established dates for submitting semiannual 

reports pursuant to 40 CFR 70.6(a)(3)(iii)(A) or 40 CFR 71.6 (a)(3)(iii)(A), you may submit the 

first and subsequent Compliance reports according to the dates the permitting authority has 

established instead of according to the dates in paragraphs (b)(1) through (b)(4) of this section.

(6) For annual Compliance reports, the first Compliance report must cover the period 

beginning on the compliance date that is specified for your affected source in §63.6595 and 

ending on December 31.
30

(7) For annual Compliance reports, the first Compliance report must be postmarked or 

delivered no later than January 31 following the end of the first calendar year after the 

compliance date that is specified for your affected source in §63.6595.

(8) For annual Compliance reports, each subsequent Compliance report must cover the 

annual reporting period from January 1 through December 31.

(9) For annual Compliance reports, each subsequent Compliance report must be 

postmarked or delivered no later than January 31.

(c) The Compliance report must contain the information in paragraphs (c)(1) through (6) 

of this section.

(1) Company name and address.

(2) Statement by a responsible official, with that official's name, title, and signature, 

certifying the accuracy of the content of the report.

(3) Date of report and beginning and ending dates of the reporting period.

(4) If you had a malfunction during the reporting period, the compliance report must 

include the number, duration, and a brief description for each type of malfunction which 

occurred during the reporting period and which caused or may have caused any applicable 

emission limitation to be exceeded. The report must also include a description of actions taken 

by an owner or operator during a malfunction of an affected source to minimize emissions in 

accordance with §63.6605(b), including actions taken to correct a malfunction.

(5) If there are no deviations from any emission or operating limitations that apply to you, 

a statement that there were no deviations from the emission or operating limitations during the 

reporting period.

(6) If there were no periods during which the continuous monitoring system (CMS), 

including CEMS and CPMS, was out-of-control, as specified in §63.8(c)(7), a statement that 

there were no periods during which the CMS was out-of-control during the reporting period.

(d) For each deviation from an emission or operating limitation that occurs for a 

stationary RICE where you are not using a CMS to comply with the emission or operating 

limitations in this subpart, the Compliance report must contain the information in paragraphs 

(c)(1) through (4) of this section and the information in paragraphs (d)(1) and (2) of this section.

(1) The total operating time of the stationary RICE at which the deviation occurred 

during the reporting period.
31

(2) Information on the number, duration, and cause of deviations (including unknown 

cause, if applicable), as applicable, and the corrective action taken.

(e) For each deviation from an emission or operating limitation occurring for a stationary

RICE where you are using a CMS to comply with the emission and operating limitations in this 

subpart, you must include information in paragraphs (c)(1) through (4) and (e)(1) through (12) of 

this section.

(1) The date and time that each malfunction started and stopped.

(2) The date, time, and duration that each CMS was inoperative, except for zero (lowlevel) and high-level checks.

(3) The date, time, and duration that each CMS was out-of-control, including the 

information in §63.8(c)(8).

(4) The date and time that each deviation started and stopped, and whether each deviation 

occurred during a period of malfunction or during another period.

(5) A summary of the total duration of the deviation during the reporting period, and the 

total duration as a percent of the total source operating time during that reporting period.

(6) A breakdown of the total duration of the deviations during the reporting period into 

those that are due to control equipment problems, process problems, other known causes, and 

other unknown causes.

(7) A summary of the total duration of CMS downtime during the reporting period, and 

the total duration of CMS downtime as a percent of the total operating time of the stationary

RICE at which the CMS downtime occurred during that reporting period.

(8) An identification of each parameter and pollutant (CO or formaldehyde) that was 

monitored at the stationary RICE.

(9) A brief description of the stationary RICE.

(10) A brief description of the CMS.

(11) The date of the latest CMS certification or audit.

(12) A description of any changes in CMS, processes, or controls since the last reporting 

period.

(f) Each affected source that has obtained a title V operating permit pursuant to 40 CFR 

part 70 or 71 must report all deviations as defined in this subpart in the semiannual monitoring 

report required by 40 CFR 70.6 (a)(3)(iii)(A) or 40 CFR 71.6(a)(3)(iii)(A). If an affected source 
32

submits a Compliance report pursuant to Table 7 of this subpart along with, or as part of, the 

semiannual monitoring report required by 40 CFR 70.6(a)(3)(iii)(A) or 40 CFR 

71.6(a)(3)(iii)(A), and the Compliance report includes all required information concerning 

deviations from any emission or operating limitation in this subpart, submission of the 

Compliance report shall be deemed to satisfy any obligation to report the same deviations in the 

semiannual monitoring report. However, submission of a Compliance report shall not otherwise 

affect any obligation the affected source may have to report deviations from permit requirements 

to the permit authority.

(g) If you are operating as a new or reconstructed stationary RICE which fires landfill gas 

or digester gas equivalent to 10 percent or more of the gross heat input on an annual basis, you 

must submit an annual report according to Table 7 of this subpart by the date specified unless the 

Administrator has approved a different schedule, according to the information described in 

paragraphs (b)(1) through (b)(5) of this section. You must report the data specified in (g)(1) 

through (g)(3) of this section.

(1) Fuel flow rate of each fuel and the heating values that were used in your calculations. 

You must also demonstrate that the percentage of heat input provided by landfill gas or digester 

gas is equivalent to 10 percent or more of the total fuel consumption on an annual basis.

(2) The operating limits provided in your federally enforceable permit, and any

deviations from these limits.

(3) Any problems or errors suspected with the meters.

§63.6655 What records must I keep?

(a) If you must comply with the emission and operating limitations, you must keep the 

records described in paragraphs (a)(1) through (a)(5), (b)(1) through (b)(3) and (c) of this 

section.

(1) A copy of each notification and report that you submitted to comply with this subpart, 

including all documentation supporting any Initial Notification or Notification of Compliance 

Status that you submitted, according to the requirement in §63.10(b)(2)(xiv).

(2) Records of the occurrence and duration of each malfunction of operation (i.e.,process 

equipment) or the air pollution control and monitoring equipment.

(3) Records of performance tests and performance evaluations as required in 

§63.10(b)(2)(viii).
33

(4) Records of all required maintenance performed on the air pollution control and 

monitoring equipment.

(5) Records of actions taken during periods of malfunction to minimize emissions in 

accordance with §63.6605(b), including corrective actions to restore malfunctioning process and 

air pollution control and monitoring equipment to its normal or usual manner of operation.

(b) For each CEMS or CPMS, you must keep the records listed in paragraphs (b)(1) 

through (3) of this section.

(1) Records described in §63.10(b)(2)(vi) through (xi).

(2) Previous ( i.e., superseded) versions of the performance evaluation plan as required in 

§63.8(d)(3).

(3) Requests for alternatives to the relative accuracy test for CEMS or CPMS as required 

in §63.8(f)(6)(i), if applicable.

(c) If you are operating a new or reconstructed stationary RICE which fires landfill gas or 

digester gas equivalent to 10 percent or more of the gross heat input on an annual basis, you must 

keep the records of your daily fuel usage monitors.

(d) You must keep the records required in Table 6 of this subpart to show continuous 

compliance with each emission or operating limitation that applies to you.

(e) You must keep records of the maintenance conducted on the stationary RICE in order 

to demonstrate that you operated and maintained the stationary RICE and after-treatment control 

device (if any) according to your own maintenance plan if you own or operate any of the

following stationary RICE;

(1) An existing stationary RICE with a site rating of less than 100 brake HP located at a 

major source of HAP emissions.

(2) An existing stationary emergency RICE.

(3) An existing stationary RICE located at an area source of HAP emissions subject to 

management practices as shown in Table 2d to this subpart.

(f) If you own or operate any of the stationary RICE in paragraphs (f)(1) or (2) of this 

section, you must keep records of the hours of operation of the engine that is recorded through 

the non-resettable hour meter. The owner or operator must document how many hours are spent 

for emergency operation, including what classified the operation as emergency and how many

hours are spent for non-emergency operation. If the engines are used for demand response 
34

operation, the owner or operator must keep records of the notification of the emergency situation, 

and the time the engine was operated as part of demand response.

(1) An existing emergency stationary RICE with a site rating of less than or equal to 500 

brake HP located at a major source of HAP emissions that does not meet the standards applicable 

to non-emergency engines.

(2) An existing emergency stationary RICE located at an area source of HAP emissions 

that does not meet the standards applicable to non-emergency engines.

§63.6660 In what form and how long must I keep my records?

(a) Your records must be in a form suitable and readily available for expeditious review 

according to §63.10(b)(1).

(b) As specified in §63.10(b)(1), you must keep each record for 5 years following the 

date of each occurrence, measurement, maintenance, corrective action, report, or record.

(c) You must keep each record readily accessible in hard copy or electronic form for at 

least 5 years after the date of each occurrence, measurement, maintenance, corrective action, 

report, or record, according to §63.10(b)(1).

Other Requirements and Information

§63.6665 What parts of the General Provisions apply to me?

Table 8 to this subpart shows which parts of the General Provisions in §§63.1 through 63.15 

apply to you. If you own or operate a new or reconstructed stationary RICE with a site rating of 

less than or equal to 500 brake HP located at a major source of HAP emissions (except new or 

reconstructed 4SLB engines greater than or equal to 250 and less than or equal to 500 brake HP), 

a new or reconstructed stationary RICE located at an area source of HAP emissions, or any of the 

following RICE with a site rating of more than 500 brake HP located at a major source of HAP 

emissions, you do not need to comply with any of the requirements of the General Provisions 

specified in Table 8: An existing 2SLB stationary RICE, an existing 4SLB stationary RICE, an 

existing stationary RICE that combusts landfill or digester gas equivalent to 10 percent or more 

of the gross heat input on an annual basis, an existing emergency stationary RICE, or an existing 

limited use stationary RICE. If you own or operate any of the following RICE with a site rating 

of more than 500 brake HP located at a major source of HAP emissions, you do not need to 

comply with the requirements in the General Provisions specified in Table 8 except for the initial 

notification requirements: A new stationary RICE that combusts landfill gas or digester gas 
35

equivalent to 10 percent or more of the gross heat input on an annual basis, a new emergency

stationary RICE, or a new limited use stationary RICE.

§63.6670 Who implements and enforces this subpart?

(a) This subpart is implemented and enforced by the U.S. EPA, or a delegated authority

such as your State, local, or tribal agency. If the U.S. EPA Administrator has delegated authority 

to your State, local, or tribal agency, then that agency (as well as the U.S. EPA) has the authority 

to implement and enforce this subpart. You should contact your U.S. EPA Regional Office to 

find out whether this subpart is delegated to your State, local, or tribal agency.

(b) In delegating implementation and enforcement authority of this subpart to a State, 

local, or tribal agency under 40 CFR part 63, subpart E, the authorities contained in paragraph (c) 

of this section are retained by the Administrator of the U.S. EPA and are not transferred to the 

State, local, or tribal agency.

(c) The authorities that will not be delegated to State, local, or tribal agencies are:

(1) Approval of alternatives to the non-opacity emission limitations and operating 

limitations in §63.6600 under §63.6(g).

(2) Approval of major alternatives to test methods under §63.7(e)(2)(ii) and (f) and as 

defined in §63.90.

(3) Approval of major alternatives to monitoring under §63.8(f) and as defined in §63.90.

(4) Approval of major alternatives to recordkeeping and reporting under §63.10(f) and as 

defined in §63.90.

(5) Approval of a performance test which was conducted prior to the effective date of the 

rule, as specified in §63.6610(b).

§63.6675 What definitions apply to this subpart?

Terms used in this subpart are defined in the Clean Air Act (CAA); in 40 CFR 63.2, the General 

Provisions of this part; and in this section as follows:

Alaska Railbelt Grid means the service areas of the six regulated public utilities that 

extend from Fairbanks to Anchorage and the Kenai Peninsula. These utilities are Golden Valley

Electric Association; Chugach Electric Association; Matanuska Electric Association; Homer 

Electric Association; Anchorage Municipal Light & Power; and the City of Seward Electric 

System.
36

Area source means any stationary source of HAP that is not a major source as defined in 

part 63.

Associated equipment as used in this subpart and as referred to in section 112(n)(4) of the 

CAA, means equipment associated with an oil or natural gas exploration or production well, and 

includes all equipment from the well bore to the point of custody transfer, except glycol 

dehydration units, storage vessels with potential for flash emissions, combustion turbines, and 

stationary RICE.

Black start engine means an engine whose only purpose is to start up a combustion 

turbine.

CAA means the Clean Air Act (42 U.S.C. 7401 et seq., as amended by Public Law 101–

549, 104 Stat. 2399).

Commercial emergency stationary RICE means an emergency stationary RICE used in 

commercial establishments such as office buildings, hotels, stores, telecommunications facilities, 

restaurants, financial institutions such as banks, doctor's offices, and sports and performing arts 

facilities.

Compression ignition means relating to a type of stationary internal combustion engine 

that is not a spark ignition engine.

Custody transfer means the transfer of hydrocarbon liquids or natural gas: After 

processing and/or treatment in the producing operations, or from storage vessels or automatic 

transfer facilities or other such equipment, including product loading racks, to pipelines or any 

other forms of transportation. For the purposes of this subpart, the point at which such liquids or 

natural gas enters a natural gas processing plant is a point of custody transfer.

Deviation means any instance in which an affected source subject to this subpart, or an 

owner or operator of such a source:

(1) Fails to meet any requirement or obligation established by this subpart, including but 

not limited to any emission limitation or operating limitation;

(2) Fails to meet any term or condition that is adopted to implement an applicable 

requirement in this subpart and that is included in the operating permit for any affected source 

required to obtain such a permit; or

(3) Fails to meet any emission limitation or operating limitation in this subpart during 

malfunction, regardless or whether or not such failure is permitted by this subpart.
37

(4) Fails to satisfy the general duty to minimize emissions established by §63.6(e)(1)(i).

Diesel engine means any stationary RICE in which a high boiling point liquid fuel 

injected into the combustion chamber ignites when the air charge has been compressed to a 

temperature sufficiently high for auto-ignition. This process is also known as compression 

ignition.

Diesel fuel means any liquid obtained from the distillation of petroleum with a boiling 

point of approximately 150 to 360 degrees Celsius. One commonly used form is fuel oil number 

2. Diesel fuel also includes any non-distillate fuel with comparable physical and chemical 

properties ( e.g. biodiesel) that is suitable for use in compression ignition engines.

Digester gas means any gaseous by-product of wastewater treatment typically formed 

through the anaerobic decomposition of organic waste materials and composed principally of 

methane and CO2.

Dual-fuel engine means any stationary RICE in which a liquid fuel (typically diesel fuel) 

is used for compression ignition and gaseous fuel (typically natural gas) is used as the primary

fuel.

Emergency stationary RICE means any stationary reciprocating internal combustion 

engine that meets all of the criteria in paragraphs (1) through (3) of this definition. All 

emergency stationary RICE must comply with the requirements specified in §63.6640(f) in order 

to be considered emergency stationary RICE. If the engine does not comply with the 

requirements specified in §63.6640(f), then it is not considered to be an emergency stationary

RICE under this subpart.

(1) The stationary RICE is operated to provide electrical power or mechanical work 

during an emergency situation. Examples include stationary RICE used to produce power for 

critical networks or equipment (including power supplied to portions of a facility) when electric 

power from the local utility (or the normal power source, if the facility runs on its own power 

production) is interrupted, or stationary RICE used to pump water in the case of fire or flood, etc.

(2) The stationary RICE is operated under limited circumstances for situations not 

included in paragraph (1) of this definition, as specified in §63.6640(f). 

(3) The stationary RICE operates as part of a financial arrangement with another entity in 

situations not included in paragraph (1) of this definition only as allowed in §63.6640(f)(2)(ii) or 

(iii) and §63.6640(f)(4)(i).
38

Engine startup means the time from initial start until applied load and engine and 

associated equipment reaches steady state or normal operation. For stationary engine with 

catalytic controls, engine startup means the time from initial start until applied load and engine 

and associated equipment, including the catalyst, reaches steady state or normal operation.

Four-stroke engine means any type of engine which completes the power cycle in two 

crankshaft revolutions, with intake and compression strokes in the first revolution and power and 

exhaust strokes in the second revolution.

Gaseous fuel means a material used for combustion which is in the gaseous state at 

standard atmospheric temperature and pressure conditions.

Gasoline means any fuel sold in any State for use in motor vehicles and motor vehicle 

engines, or nonroad or stationary engines, and commonly or commercially known or sold as 

gasoline.

Glycol dehydration unit means a device in which a liquid glycol (including, but not 

limited to, ethylene glycol, diethylene glycol, or triethylene glycol) absorbent directly contacts a 

natural gas stream and absorbs water in a contact tower or absorption column (absorber). The 

glycol contacts and absorbs water vapor and other gas stream constituents from the natural gas 

and becomes “rich” glycol. This glycol is then regenerated in the glycol dehydration unit 

reboiler. The “lean” glycol is then recycled.

Hazardous air pollutants (HAP) means any air pollutants listed in or pursuant to section 

112(b) of the CAA.

Institutional emergency stationary RICE means an emergency stationary RICE used in 

institutional establishments such as medical centers, nursing homes, research centers, institutions 

of higher education, correctional facilities, elementary and secondary schools, libraries, religious 

establishments, police stations, and fire stations.

ISO standard day conditions means 288 degrees Kelvin (15 degrees Celsius), 60 percent 

relative humidity and 101.3 kilopascals pressure.

Landfill gas means a gaseous by-product of the land application of municipal refuse 

typically formed through the anaerobic decomposition of waste materials and composed 

principally of methane and CO2.

Lean burn engine means any two-stroke or four-stroke spark ignited engine that does not 

meet the definition of a rich burn engine.
39

Limited use stationary RICE means any stationary RICE that operates less than 100 hours 

per year.

Liquefied petroleum gas means any liquefied hydrocarbon gas obtained as a by-product 

in petroleum refining of natural gas production.

Liquid fuel means any fuel in liquid form at standard temperature and pressure, including 

but not limited to diesel, residual/crude oil, kerosene/naphtha (jet fuel), and gasoline.

Major Source, as used in this subpart, shall have the same meaning as in §63.2, except 

that:

(1) Emissions from any oil or gas exploration or production well (with its associated 

equipment (as defined in this section)) and emissions from any pipeline compressor station or 

pump station shall not be aggregated with emissions from other similar units, to determine 

whether such emission points or stations are major sources, even when emission points are in a 

contiguous area or under common control;

(2) For oil and gas production facilities, emissions from processes, operations, or 

equipment that are not part of the same oil and gas production facility, as defined in §63.1271 of 

subpart HHH of this part, shall not be aggregated;

(3) For production field facilities, only HAP emissions from glycol dehydration units, 

storage vessel with the potential for flash emissions, combustion turbines and reciprocating 

internal combustion engines shall be aggregated for a major source determination; and

(4) Emissions from processes, operations, and equipment that are not part of the same 

natural gas transmission and storage facility, as defined in §63.1271 of subpart HHH of this part, 

shall not be aggregated.

Malfunction means any sudden, infrequent, and not reasonably preventable failure of air 

pollution control equipment, process equipment, or a process to operate in a normal or usual 

manner which causes, or has the potential to cause, the emission limitations in an applicable 

standard to be exceeded. Failures that are caused in part by poor maintenance or careless 

operation are not malfunctions.

Natural gas means a naturally occurring mixture of hydrocarbon and non-hydrocarbon 

gases found in geologic formations beneath the Earth's surface, of which the principal constituent 

is methane. Natural gas may be field or pipeline quality.
40

Non-selective catalytic reduction (NSCR) means an add-on catalytic nitrogen oxides 

(NOX) control device for rich burn engines that, in a two-step reaction, promotes the conversion 

of excess oxygen, NOX, CO, and volatile organic compounds (VOC) into CO2, nitrogen, and 

water.

Oil and gas production facility as used in this subpart means any grouping of equipment

where hydrocarbon liquids are processed, upgraded ( i.e., remove impurities or other constituents 

to meet contract specifications), or stored prior to the point of custody transfer; or where natural 

gas is processed, upgraded, or stored prior to entering the natural gas transmission and storage 

source category. For purposes of a major source determination, facility (including a building, 

structure, or installation) means oil and natural gas production and processing equipment that is 

located within the boundaries of an individual surface site as defined in this section. Equipment 

that is part of a facility will typically be located within close proximity to other equipment 

located at the same facility. Pieces of production equipment or groupings of equipment located 

on different oil and gas leases, mineral fee tracts, lease tracts, subsurface or surface unit areas, 

surface fee tracts, surface lease tracts, or separate surface sites, whether or not connected by a 

road, waterway, power line or pipeline, shall not be considered part of the same facility. 

Examples of facilities in the oil and natural gas production source category include, but are not 

limited to, well sites, satellite tank batteries, central tank batteries, a compressor station that 

transports natural gas to a natural gas processing plant, and natural gas processing plants.

Oxidation catalyst means an add-on catalytic control device that controls CO and VOC 

by oxidation.

Peaking unit or engine means any standby engine intended for use during periods of high 

demand that are not emergencies.

Percent load means the fractional power of an engine compared to its maximum 

manufacturer's design capacity at engine site conditions. Percent load may range between 0 

percent to above 100 percent.

Potential to emit means the maximum capacity of a stationary source to emit a pollutant 

under its physical and operational design. Any physical or operational limitation on the capacity

of the stationary source to emit a pollutant, including air pollution control equipment and 

restrictions on hours of operation or on the type or amount of material combusted, stored, or 

processed, shall be treated as part of its design if the limitation or the effect it would have on 
41

emissions is federally enforceable. For oil and natural gas production facilities subject to subpart 

HH of this part, the potential to emit provisions in §63.760(a) may be used. For natural gas 

transmission and storage facilities subject to subpart HHH of this part, the maximum annual 

facility gas throughput for storage facilities may be determined according to §63.1270(a)(1) and 

the maximum annual throughput for transmission facilities may be determined according to 

§63.1270(a)(2).

Production field facility means those oil and gas production facilities located prior to the 

point of custody transfer.

Production well means any hole drilled in the earth from which crude oil, condensate, or 

field natural gas is extracted.

Propane means a colorless gas derived from petroleum and natural gas, with the molecular 

structure C3H8.

Remote stationary RICE means stationary RICE meeting any of the following criteria: 

(1) Stationary RICE located in an offshore area that is beyond the line of ordinary low 

water along that portion of the coast of the United States that is in direct contact with the open 

seas and beyond the line marking the seaward limit of inland waters.

(2) Stationary RICE located on a pipeline segment that meets both of the criteria in 

paragraphs (2)(i) and (ii) of this definition.

(i) A pipeline segment with 10 or fewer buildings intended for human occupancy within 

220 yards (200 meters) on either side of the centerline of any continuous 1-mile (1.6 kilometers) 

length of pipeline. Each separate dwelling unit in a multiple dwelling unit building is counted as 

a separate building intended for human occupancy.

(ii) The pipeline segment does not lie within 100 yards (91 meters) of either a building or 

a small, well-defined outside area (such as a playground, recreation area, outdoor theater, or 

other place of public assembly) that is occupied by 20 or more persons on at least 5 days a week 

for 10 weeks in any 12-month period. The days and weeks need not be consecutive. The building 

or area is considered occupied for a full day if it is occupied for any portion of the day. 

(iii) For purposes of this paragraph (2), the term pipeline segment means all parts of 

those physical facilities through which gas moves in transportation, including but not limited to 

pipe, valves, and other appurtenance attached to pipe, compressor units, metering stations, 

regulator stations, delivery stations, holders, and fabricated assemblies. Stationary RICE located 
42

within 50 yards (46 m) of the pipeline segment providing power for equipment on a pipeline 

segment are part of the pipeline segment. Transportation of gas means the gathering, 

transmission, or distribution of gas by pipeline, or the storage of gas. A building is intended for 

human occupancy if its primary use is for a purpose involving the presence of humans.

(3) Stationary RICE that are not located on gas pipelines and that have 5 or fewer 

buildings intended for human occupancy within a 0.25 mile radius around the engine. A building 

is intended for human occupancy if its primary use is for a purpose involving the presence of 

humans.

Residential emergency stationary RICE means an emergency stationary RICE used in 

residential establishments such as homes or apartment buildings.

Responsible official means responsible official as defined in 40 CFR 70.2.

Rich burn engine means any four-stroke spark ignited engine where the manufacturer's 

recommended operating air/fuel ratio divided by the stoichiometric air/fuel ratio at full load 

conditions is less than or equal to 1.1. Engines originally manufactured as rich burn engines, but 

modified prior to December 19, 2002 with passive emission control technology for NOX(such as 

pre-combustion chambers) will be considered lean burn engines. Also, existing engines where 

there are no manufacturer's recommendations regarding air/fuel ratio will be considered a rich 

burn engine if the excess oxygen content of the exhaust at full load conditions is less than or 

equal to 2 percent.

Site-rated HP means the maximum manufacturer's design capacity at engine site 

conditions.

Spark ignition means relating to either: A gasoline-fueled engine; or any other type of 

engine with a spark plug (or other sparking device) and with operating characteristics 

significantly similar to the theoretical Otto combustion cycle. Spark ignition engines usually use 

a throttle to regulate intake air flow to control power during normal operation. Dual-fuel engines 

in which a liquid fuel (typically diesel fuel) is used for CI and gaseous fuel (typically natural gas) 

is used as the primary fuel at an annual average ratio of less than 2 parts diesel fuel to 100 parts 

total fuel on an energy equivalent basis are spark ignition engines.

Stationary reciprocating internal combustion engine (RICE) means any reciprocating 

internal combustion engine which uses reciprocating motion to convert heat energy into 

mechanical work and which is not mobile. Stationary RICE differ from mobile RICE in that a 
43

stationary RICE is not a non-road engine as defined at 40 CFR 1068.30, and is not used to propel 

a motor vehicle or a vehicle used solely for competition.

Stationary RICE test cell/stand means an engine test cell/stand, as defined in subpart 

PPPPP of this part, that tests stationary RICE.

Stoichiometric means the theoretical air-to-fuel ratio required for complete combustion.

Storage vessel with the potential for flash emissions means any storage vessel that 

contains a hydrocarbon liquid with a stock tank gas-to-oil ratio equal to or greater than 0.31 

cubic meters per liter and an American Petroleum Institute gravity equal to or greater than 40 

degrees and an actual annual average hydrocarbon liquid throughput equal to or greater than 

79,500 liters per day. Flash emissions occur when dissolved hydrocarbons in the fluid evolve 

from solution when the fluid pressure is reduced.

Subpart means 40 CFR part 63, subpart ZZZZ.

Surface site means any combination of one or more graded pad sites, gravel pad sites, 

foundations, platforms, or the immediate physical location upon which equipment is physically 

affixed.

Two-stroke engine means a type of engine which completes the power cycle in single 

crankshaft revolution by combining the intake and compression operations into one stroke and 

the power and exhaust operations into a second stroke. This system requires auxiliary scavenging 

and inherently runs lean of stoichiometric.

Table 1a to Subpart ZZZZ of Part 63—Emission Limitations for Existing, New, and 

Reconstructed Spark Ignition, 4SRB Stationary RICE >500 HP Located at a Major Source 

of HAP Emissions

As stated in §§63.6600 and 63.6640, you must comply with the following emission limitations at 

100 percent load plus or minus 10 percent for existing, new and reconstructed 4SRB stationary

RICE >500 HP located at a major source of HAP emissions:

For each . 

. .

You must meet the following emission 

limitation, except during periods of 

startup . . .

During periods of startup you must . . 

.
44

1. 4SRB 

stationary

RICE

a. Reduce formaldehyde emissions by 76 

percent or more. If you commenced 

construction or reconstruction between 

December 19, 2002 and June 15, 2004, you 

may reduce formaldehyde emissions by 75 

percent or more until June 15, 2007 or

Minimize the engine's time spent at idle 

and minimize the engine's startup time at 

startup to a period needed for 

appropriate and safe loading of the

engine, not to exceed 30 minutes, after 

which time the non-startup emission 

limitations apply.

1

 b. Limit the concentration of formaldehyde 

in the stationary RICE exhaust to 350 

ppbvd or less at 15 percent O2

1

Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.6(g) for 

alternative work practices.

Table 1b to Subpart ZZZZ of Part 63. Operating Limitations for Existing, New, and 

Reconstructed SI 4SRB Stationary RICE >500 HP Located at a Major Source of HAP 

Emissions 

As stated in §§63.6600, 63.6603, 63.6630 and 63.6640, you must comply with the following 

operating limitations for existing, new and reconstructed 4SRB stationary RICE >500 HP located 

at a major source of HAP emissions:

For each... You must meet the following operating 

limitation, except during periods of 

startup...

1. existing, new and reconstructed 4SRB 

stationary RICE >500 HP located at a major 

source of HAP emissions complying with the 

requirement to reduce formaldehyde emissions 

by 76 percent or more (or by 75 percent or 

a. maintain your catalyst so that the pressure 

drop across the catalyst does not change by

more than 2 inches of water at 100 percent load 

plus or minus 10 percent from the pressure 

drop across the catalyst measured during the 
45

more, if applicable) and using NSCR; 

or 

existing, new and reconstructed 4SRB 

stationary RICE >500 HP located at a major 

source of HAP emissions complying with the 

requirement to limit the concentration of 

formaldehyde in the stationary RICE exhaust 

to 350 ppbvd or less at 15 percent O2 and using 

NSCR;

initial performance test; and

b. maintain the temperature of your stationary

RICE exhaust so that the catalyst inlet 

temperature is greater than or equal to 750°F 

and less than or equal to 1250°F.1

2. existing, new and reconstructed 4SRB 

stationary RICE >500 HP located at a major 

source of HAP emissions complying with the 

requirement to reduce formaldehyde emissions 

by 76 percent or more (or by 75 percent or 

more, if applicable) and not using NSCR; 

or 

existing, new and reconstructed 4SRB 

stationary RICE >500 HP located at a major 

source of HAP emissions complying with the 

requirement to limit the concentration of 

formaldehyde in the stationary RICE exhaust 

to 350 ppbvd or less at 15 percent O2 and not 

using NSCR.

Comply with any operating limitations 

approved by the Administrator.

1

Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.8(f) for a 

different temperature range.

Table 2b to Subpart ZZZZ of Part 63. Operating Limitations for New and Reconstructed 

2SLB and CI Stationary RICE >500 HP Located at a Major Source of HAP Emissions, 

New and Reconstructed 4SLB Stationary RICE ≥250 HP Located at a Major Source of 
46

HAP Emissions, Existing CI Stationary RICE >500 HP, and Existing 4SLB Stationary 

RICE >500 HP Located at an Area Source of HAP Emissions 

As stated in §§63.6600, 63.6601, 63.6603, 63.6630, and 63.6640, you must comply with the 

following operating limitations for new and reconstructed 2SLB and CI stationary RICE >500 

HP located at a major source of HAP emissions; new and reconstructed 4SLB stationary RICE 

≥250 HP located at a major source of HAP emissions; and existing CI stationary RICE >500 HP:

For each... You must meet the following operating 

limitation, except during periods of 

startup...

1. New and reconstructed 2SLB and CI

stationary RICE >500 HP located at a major 

source of HAP emissions and new and 

reconstructed 4SLB stationary RICE ≥250 HP 

located at a major source of HAP emissions 

complying with the requirement to reduce CO 

emissions and using an oxidation catalyst; 

and 

New and reconstructed 2SLB and CI stationary

RICE >500 HP located at a major source of 

HAP emissions and new and reconstructed 

4SLB stationary RICE ≥250 HP located at a 

major source of HAP emissions complying 

with the requirement to limit the concentration 

of formaldehyde in the stationary RICE 

exhaust and using an oxidation catalyst

a. maintain your catalyst so that the pressure 

drop across the catalyst does not change by

more than 2 inches of water at 100 percent load 

plus or minus 10 percent from the pressure 

drop across the catalyst that was measured 

during the initial performance test; and

b. maintain the temperature of your stationary

RICE exhaust so that the catalyst inlet 

temperature is greater than or equal to 450°F 

and less than or equal to 1350°F.1
47

2. Existing CI stationary RICE >500 HP 

complying with the requirement to limit or 

reduce the concentration of CO in the 

stationary RICE exhaust and using an 

oxidation catalyst 

a. maintain your catalyst so that the pressure 

drop across the catalyst does not change by

more than 2 inches of water from the pressure 

drop across the catalyst that was measured 

during the initial performance test; and

b. maintain the temperature of your stationary

RICE exhaust so that the catalyst inlet 

temperature is greater than or equal to 450°F 

and less than or equal to 1350°F.1
48

3. New and reconstructed 2SLB and CI

stationary RICE >500 HP located at a major 

source of HAP emissions and new and 

reconstructed 4SLB stationary RICE ≥250 HP 

located at a major source of HAP emissions 

complying with the requirement to reduce CO 

emissions and not using an oxidation catalyst; 

and 

New and reconstructed 2SLB and CI stationary

RICE >500 HP located at a major source of 

HAP emissions and new and reconstructed 

4SLB stationary RICE ≥250 HP located at a 

major source of HAP emissions complying 

with the requirement to limit the concentration 

of formaldehyde in the stationary RICE 

exhaust and not using an oxidation catalyst

and

existing CI stationary RICE >500 HP 

complying with the requirement to limit or 

reduce the concentration of CO in the 

stationary RICE exhaust and not using an 

oxidation catalyst

Comply with any operating limitations 

approved by the Administrator.

1

Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.8(f) for a 

different temperature range.

Table 2c to Subpart ZZZZ of Part 63. Requirements for Existing Compression Ignition 

Stationary RICE Located at a Major Source of HAP Emissions and Existing Spark 

Ignition Stationary RICE ≤500 HP Located at a Major Source of HAP Emissions
49

As stated in §§63.6600, 63.6602, and 63.6640, you must comply with the following requirements

for existing compression ignition stationary RICE located at a major source of HAP emissions 

and existing spark ignition stationary RICE ≤500 HP located at a major source of HAP 

emissions:

For each... You must meet the following 

requirement, except during periods 

of startup...

During periods of startup 

you must...

1. Emergency

stationary CI RICE and 

black start stationary CI 

RICE.1 

a. Change oil and filter every 500 

hours of operation or annually, 

whichever comes first;2

b. Inspect air cleaner every 1,000 

hours of operation or annually, 

whichever comes first, and replace as 

necessary; 

c. Inspect all hoses and belts every

500 hours of operation or annually, 

whichever comes first, and replace 

as necessary.

3

Minimize the engine’s time 

spent at idle and minimize the 

engine’s startup time at 

startup to a period needed for 

appropriate and safe loading 

of the engine, not to exceed 

30 minutes, after which time 

the non-startup emission 

limitations apply.

3
50

2. Non-Emergency, 

non-black start 

stationary CI RICE 

<100 HP. 

a. Change oil and filter every 1,000 

hours of operation or annually, 

whichever comes first2;

b. Inspect air cleaner every 1,000 

hours of operation or annually, 

whichever comes first, and replace as 

necessary; 

c. Inspect all hoses and belts every 

500 hours of operation or annually, 

whichever comes first, and replace 

as necessary.

3

3. Non-Emergency, 

non-black start CI 

stationary RICE 

100<HP<300 HP.

Limit concentration of CO in the 

stationary RICE exhaust to 230 

ppmvd or less at 15 percent O2.

4. Non-Emergency, 

non- black start CI 

stationary RICE 

300<HP<500.

a. Limit concentration of CO in the 

stationary RICE exhaust to 49 ppmvd 

or less at 15 percent O2; or

b. Reduce CO emissions by 70 

percent or more. 

5. Non-Emergency, 

non-black start 

stationary CI RICE 

>500 HP.

a. Limit concentration of CO in the 

stationary RICE exhaust to 23 ppmvd 

or less at 15 percent O2; or

b. Reduce CO emissions by 70 

percent or more.
51

6. Emergency

stationary SI RICE and 

black start stationary SI 

RICE.1

a. Change oil and filter every 500 

hours of operation or annually, 

whichever comes first;2

b. Inspect spark plugs every 1,000 

hours of operation or annually, 

whichever comes first, and replace as 

necessary; 

c. Inspect all hoses and belts every

500 hours of operation or annually, 

whichever comes first, and replace 

as necessary.

3

7. Non-Emergency, 

non-black start 

stationary SI RICE 

<100 HP that are not 

2SLB stationary RICE. 

a. Change oil and filter every 1,440 

hours of operation or annually, 

whichever comes first

2

;

b. Inspect spark plugs every 1,440 

hours of operation or annually, 

whichever comes first, and replace as 

necessary; 

c. Inspect all hoses and belts every

1,440 hours of operation or annually, 

whichever comes first, and replace 

as necessary.

3
52

8. Non-Emergency, 

non-black start 2SLB 

stationary SI RICE 

<100 HP.

a. Change oil and filter every 4,320 

hours of operation or annually, 

whichever comes first2;

b. Inspect spark plugs every 4,320 

hours of operation or annually, 

whichever comes first, and replace as 

necessary; 

c. Inspect all hoses and belts every

4,320 hours of operation or annually, 

whichever comes first, and replace 

as necessary.

3

9. Non-emergency, 

non-black start 2SLB 

stationary RICE 

100≤HP≤500

Limit concentration of CO in the 

stationary RICE exhaust to 225 

ppmvd or less at 15 percent O2

10. Non-emergency, 

non-black start 4SLB 

stationary RICE 

100≤HP≤500

Limit concentration of CO in the 

stationary RICE exhaust to 47 ppmvd 

or less at 15 percent O2

11. Non-emergency, 

non-black start 4SRB 

stationary RICE 

100≤HP≤500

Limit concentration of formaldehyde 

in the stationary RICE exhaust to 

10.3 ppmvd or less at 15 percent O2
53

12. Non-emergency, 

non-black start 

stationary RICE 

100≤HP≤500 which 

combusts landfill or 

digester gas equivalent 

to 10 percent or more 

of the gross heat input 

on an annual basis

Limit concentration of CO in the 

stationary RICE exhaust to 177 

ppmvd or less at 15 percent O2

1

If an emergency engine is operating during an emergency and it is not possible to shut down the 

engine in order to perform the work practice requirements on the schedule required in Table 2c 

of this subpart, or if performing the work practice on the required schedule would otherwise pose 

an unacceptable risk under federal, state, or local law, the work practice can be delayed until the 

emergency is over or the unacceptable risk under federal, state, or local law has abated. The 

work practice should be performed as soon as practicable after the emergency has ended or the 

unacceptable risk under federal, state, or local law has abated. Sources must report any failure to 

perform the work practice on the schedule required and the federal, state or local law under 

which the risk was deemed unacceptable.

2

Sources have the option to utilize an oil analysis program as described in §63.6625(i) in order to 

extend the specified oil change requirement in Table 2c of this subpart. 

3 Sources can petition the Administrator pursuant to the requirements of 40 CFR 63.6(g) for 

alternative work practices.

Table 2d to Subpart ZZZZ of Part 63. Requirements for Existing Stationary RICE 

Located at Area Sources of HAP Emissions 

As stated in §§63.6603 and 63.6640, you must comply with the following requirements for 

existing stationary RICE located at area sources of HAP emissions:
54

For each... You must meet the 

following requirement, 

except during periods of 

startup...

During periods of startup you 

must...

1. Non-Emergency, nonblack start CI stationary

RICE <300 HP

a. Change oil and filter every

1,000 hours of operation or 

annually, whichever comes 

first;1

b. Inspect air cleaner every

1,000 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; 

c. Inspect all hoses and belts 

every 500 hours of operation 

or annually, whichever 

comes first, and replace as 

necessary.

Minimize the engine’s time spent 

at idle and minimize the engine’s 

startup time at startup to a period 

needed for appropriate and safe 

loading of the engine, not to 

exceed 30 minutes, after which 

time the non-startup emission 

limitations apply.

2. Non-Emergency, nonblack start CI stationary

RICE 300<HP<500

a. Limit concentration of CO 

in the stationary RICE 

exhaust to 49 ppmvd at 15 

percent O2;

or 

b. Reduce CO emissions by

70 percent or more.
55

3. Non-Emergency, nonblack start CI stationary

RICE >500 HP

a. Limit concentration of CO 

in the stationary RICE 

exhaust to 23 ppmvd at 15 

percent O2;

or 

b. Reduce CO emissions by

70 percent or more.

4. Emergency stationary CI

RICE and black start 

stationary CI RICE2

a. Change oil and filter every

500 hours of operation or 

annually, whichever comes 

first;1

b. Inspect air cleaner every

1,000 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 500 hours of operation 

or annually, whichever 

comes first, and replace as 

necessary.
56

5. Emergency stationary SI

RICE; black start 

stationary SI RICE; nonemergency, non-black start 

4SLB stationary RICE 

>500 HP that operate 24 

hours or less per calendar 

year; non-emergency, nonblack start 4SRB stationary

RICE >500 HP that operate 

24 hours or less per 

calendar year2

a. Change oil and filter every

500 hours of operation or 

annually, whichever comes 

first;1

b. Inspect spark plugs every

1,000 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 500 hours of operation 

or annually, whichever 

comes first, and replace as 

necessary.

6. Non-emergency, nonblack start 2SLB stationary

RICE

a. Change oil and filter every

4,320 hours of operation or 

annually, whichever comes 

first;1

b. Inspect spark plugs every

4,320 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 4,320 hours of 

operation or annually, 

whichever comes first, and 

replace as necessary.
57

7. Non-emergency, nonblack start 4SLB stationary

RICE ≤500 HP; nonemergency, non-black start 

4SLB remote stationary

RICE >500 HP

a. Change oil and filter every

1,440 hours of operation or 

annually, whichever comes 

first;1

b. Inspect spark plugs every

1,440 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 1,440 hours of 

operation or annually, 

whichever comes first, and 

replace as necessary.

8. Non-emergency, nonblack start 4SLB stationary

RICE >500 HP that are not 

remote stationary RICE 

and that operate more than 

24 hours per calendar year

Install an oxidation catalyst 

to reduce HAP emissions 

from the stationary RICE
58

9. Non-emergency, nonblack start 4SRB stationary

RICE ≤500 HP; nonemergency, non-black start 

4SRB remote stationary

RICE >500 HP

a. Change oil and filter every

1,440 hours of operation or 

annually, whichever comes 

first;

1

b. Inspect spark plugs every

1,440 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 1,440 hours of 

operation or annually, 

whichever comes first, and 

replace as necessary.

10. Non-emergency, nonblack start 4SRB stationary

RICE >500 HP that are not 

remote stationary RICE 

and that operate more than 

24 hours per calendar year

Install NSCR to reduce HAP 

emissions from the 

stationary RICE 
59

11. Non-emergency, nonblack start stationary RICE 

which combusts landfill or 

digester gas equivalent to 

10 percent or more of the 

gross heat input on an 

annual basis

a. Change oil and filter every

1,440 hours of operation or 

annually, whichever comes 

first;1

b. Inspect spark plugs every

1,440 hours of operation or 

annually, whichever comes 

first, and replace as 

necessary; and

c. Inspect all hoses and belts 

every 1,440 hours of 

operation or annually, 

whichever comes first, and 

replace as necessary.

1 Sources have the option to utilize an oil analysis program as described in §63.6625(i) in order 

to extend the specified oil change requirement in Table 2d of this subpart.

2 If an emergency engine is operating during an emergency and it is not possible to shut down the 

engine in order to perform the management practice requirements on the schedule required in 

Table 2d of this subpart, or if performing the management practice on the required schedule 

would otherwise pose an unacceptable risk under federal, state, or local law, the management 

practice can be delayed until the emergency is over or the unacceptable risk under federal, state, 

or local law has abated. The management practice should be performed as soon as practicable 

after the emergency has ended or the unacceptable risk under federal, state, or local law has 

abated. Sources must report any failure to perform the management practice on the schedule 

required and the federal, state or local law under which the risk was deemed unacceptable.

Table 3 to Subpart ZZZZ of Part 63. Subsequent Performance Tests 

As stated in §§63.6615 and 63.6620, you must comply with the following subsequent 

performance test requirements:
60

For each... Complying with the 

requirement to...

You must...

1. New or reconstructed 

2SLB stationary RICE >500 

HP located at major 

sources; new or 

reconstructed 4SLB 

stationary RICE ≥250 HP 

located at major sources; 

and new or reconstructed CI

stationary RICE >500 HP 

located at major sources. 

Reduce CO emissions and 

not using a CEMS

Conduct subsequent 

performance tests 

semiannually1.

2. 4SRB stationary RICE 

≥5,000 HP located at major 

sources.

Reduce formaldehyde 

emissions

Conduct subsequent 

performance tests 

semiannually1.

3. Stationary RICE >500

HP located at major sources 

and new or reconstructed 

4SLB stationary RICE with 

a brake horsepower 

250≤HP≤500 located at 

major sources. 

Limit the concentration of 

formaldehyde in the 

stationary RICE exhaust

Conduct subsequent 

performance tests 

semiannually1.

4. Existing non-emergency, 

non-black start CI 

stationary RICE >500 HP 

that are not limited use 

stationary RICE

Limit or reduce CO 

emissions and not using a 

CEMS

Conduct subsequent 

performance tests every

8,760 hrs or 3 years, 

whichever comes first.
61

5. Existing non-emergency, 

non-black start CI 

stationary RICE >500 HP

that are limited use 

stationary RICE

Limit or reduce CO 

emissions and not using a 

CEMS

Conduct subsequent 

performance tests every

8,760 hrs or 5 years, 

whichever comes first.

1 After you have demonstrated compliance for two consecutive tests, you may reduce the 

frequency of subsequent performance tests to annually. If the results of any subsequent annual 

performance test indicate the stationary RICE is not in compliance with the CO or formaldehyde 

emission limitation, or you deviate from any of your operating limitations, you must resume 

semiannual performance tests.

Table 4 to Subpart ZZZZ of Part 63. Requirements for Performance Tests

As stated in §§63.6610, 63.6611, 63.6612, 63.6620, and 63.6640, you must comply with the 

following requirements for performance tests for stationary RICE:

For each... Complying with 

the 

requirement 

to...

You must... Using... According to the 

following 

requirements...

1. 2SLB, 

4SLB, and CI 

stationary

RICE

a. reduce CO 

emissions

i. Measure the 

O2 at the inlet 

and outlet of 

the control 

device; and

(1) Method 

3 or 3A or 

3B of 40 

CFR part 

60, 

appendix A, 

or ASTM 

Method 

D6522-00 

(a) Measurements 

to determine O2

must be made at 

the same time as 

the measurements 

for CO concentration.
62

(2005)a

(incorporate

d by

reference, 

see §63.14).

ii. Measure

the CO at the 

inlet and the 

outlet of the 

control device

(1) ASTM 

D6522-00 

(2005)a,b

(incorporated by

reference, 

see §63.14) 

or Method 

10 of 40 

CFR part 

60, 

appendix A.

(a) The CO 

concentra-tion 

must be at 15 

percent O2, dry

basis.

2. 4SRB 

stationary

RICE

a. reduce 

formaldehyde 

emissions

i. Select the 

sampling port 

location and 

the number of 

traverse 

points; and

(1) Method 

1 or 1A of 

40 CFR part 

60, 

appendix A 

§63.7(d)(1)(

i)

(a) sampling sites 

must be located at 

the inlet and outlet 

of the control 

device.
63

ii. Measure

O2 at the inlet 

and outlet of 

the control 

device; and

(1) Method 

3 or 3A or 

3B of 40 

CFR part 

60, 

appendix A, 

or ASTM 

Method 

D6522-

00(2005).

(a) measurements 

to determine O2 

concentration

must be made at 

the same time as 

the measurements 

for formaldehyde 

or THC 

concentration.

iii. Measure

moisture 

content at the 

inlet and 

outlet of the 

control 

device; and

(1) Method 

4 of 40 CFR 

part 60, 

appendix A, 

or Test 

Method 320 

of 40 CFR 

part 63, 

appendix A, 

or ASTM D 

6348-03

(a) measurements

to determine 

moisture content 

must be made at 

the same time and 

location as the 

measurements for 

formaldehyde or 

THC 

concentration.
64

iv. If 

demonstrating 

compliance 

with the 

formaldehyde 

percent 

reduction 

requirement,

measure 

formaldehyde at the 

inlet and the 

outlet of the 

control device

(1) Method 

320 or 323 

of 40 CFR 

part 63, 

appendix A; 

or ASTM 

D6348-03c, 

provided in 

ASTM 

D6348-03 

Annex A5 

(Analyte

Spiking 

Technique), 

the percent 

R must be 

greater than 

or equal to 

70 and less 

than or 

equal to 

130.

(a) formaldehyde 

concentra-tion 

must be at 15 

percent O2, dry

basis. Results of 

this test consist of 

the average of the 

three 1-hour or 

longer runs.
65

v. If 

demonstrating 

compliance 

with the THC 

percent 

reduction 

requirement, 

measure THC 

at the inlet 

and the outlet 

of the control 

device

(1) Method 

25A of 40 

CFR part 

60, 

appendix A

(a) THC 

concentra-tion 

must be at 15 

percent O2, dry

basis. Results of 

this test consist of 

the average of the 

three 1-hour or 

longer runs.

3. Stationary

RICE 

a. limit the 

concentra-tion of 

formalde-hyde

or CO in the 

stationary RICE 

exhaust

i. Select the 

sampling port 

location and 

the number of 

traverse 

points; and

(1) Method 

1 or 1A of 

40 CFR part 

60, 

appendix A 

§63.7(d)(1)(

i)

(a) if using a 

control device, the 

sampling site must 

be located at the 

outlet of the 

control device.

ii. Determine

the O2

concentration 

of the 

stationary

RICE exhaust 

at the 

sampling port 

location; and

(1) Method 

3 or 3A or 

3B of 40 

CFR part 

60, 

appendix A, 

or ASTM 

Method 

D6522-

00(2005).

(a) measurements 

to determine O2 

concentra-tion 

must be made at 

the same time and 

location as the 

measurements for 

formaldehyde or 

CO concentration.

iii. Measure (1) Method (a) measurements 
66

moisture 

content of the 

station-ary 

RICE exhaust 

at the 

sampling port 

location; and

4 of 40 CFR 

part 60, 

appendix A, 

or Test 

Method 320 

of 40 CFR 

part 63, 

appendix A, 

or ASTM D 

6348-03

to determine 

moisture content 

must be made at 

the same time and 

location as the 

measurements for 

formaldehyde or 

CO concentration.

iv. Measure

formaldehyde at the 

exhaust of the 

station-ary 

RICE; or

(1) Method 

320 or 323 

of 40 CFR 

part 63, 

appendix A; 

or ASTM 

D6348-03c, 

provided in 

ASTM 

D6348-03 

Annex A5 

(Analyte 

Spiking 

Technique), 

the percent 

R must be 

greater than 

or equal to 

70 and less 

than or 

equal to 

(a) Formaldehyde 

concentration 

must be at 15 

percent O2, dry

basis. Results of 

this test consist of 

the average of the 

three 1-hour or 

longer runs.
67

130.

v. measure 

CO at the 

exhaust of the 

station-ary 

RICE.

(1) Method 

10 of 40 

CFR part 

60, 

appendix A, 

ASTM 

Method 

D6522-00 

(2005)a, 

Method 320 

of 40 CFR 

part 63, 

appendix A, 

or ASTM 

D6348-03.

(a) CO 

concentration 

must be at 15 

percent O2, dry

basis. Results of 

this test consist of 

the average of the 

three 1-hour or 

longer runs.

aYou may obtain a copy of ASTM-D6522-00 (2005) from at least one of the following 

addresses: American Society for Testing and Materials, 100 Barr Harbor Drive, West 

Conshohocken, PA 19428-2959, or University Microfilms International, 300 North Zeeb Road, 

Ann Arbor, MI 48106. ASTM-D6522-00 (2005) may be used to test both CI and SI stationary

RICE. 

bYou may also use Method 320 of 40 CFR part 63, appendix A, or ASTM D6348-03.

cYou may obtain a copy of ASTM-D6348-03 from at least one of the following addresses: 

American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 

19428-2959, or University Microfilms International, 300 North Zeeb Road, Ann Arbor, MI 

48106.

Table 5 to Subpart ZZZZ of Part 63. Initial Compliance with Emission Limitations and 

Operating Limitations
68

As stated in §§63.6612, 63.6625 and 63.6630, you must initially comply with the emission and 

operating limitations as required by the following: 

For each . . . Complying with the 

requirement to . . .

You have demonstrated 

initial compliance if . . .

1. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source 

of HAP, new or 

reconstructed nonemergency 4SLB 

stationary RICE ≥250 HP 

located at a major source 

of HAP, non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP. 

a. Reduce CO emissions 

and using oxidation 

catalyst, and using a CPMS

i. The average reduction of 

emissions of CO determined 

from the initial performance 

test achieves the required 

CO percent reduction; and

ii. You have installed a 

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 

catalyst pressure drop and 

catalyst inlet temperature 

during the initial

performance test.
69

2. Non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP.

a. Limit the concentration 

of CO, using oxidation 

catalyst, and using a CPMS

i. The average CO 

concentration determined 

from the initial performance 

test is less than or equal to 

the CO emission limitation; 

and

ii. You have installed a 

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 

catalyst pressure drop and 

catalyst inlet temperature 

during the initial 

performance test.

3. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source 

of HAP, new or 

reconstructed nonemergency 4SLB 

stationary RICE ≥250 HP 

located at a major source 

a. Reduce CO emissions 

and not using oxidation 

catalyst

i. The average reduction of 

emissions of CO determined 

from the initial performance 

test achieves the required 

CO percent reduction; and

ii. You have installed a 

CPMS to continuously
70

of HAP, non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP.

monitor operating 

parameters approved by the 

Administrator (if any) 

according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 

approved operating 

parameters (if any) during 

the initial performance test.

4. Non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP.

a. Limit the concentration 

of CO, and not using 

oxidation catalyst

i. The average CO 

concentration determined 

from the initial performance 

test is less than or equal to 

the CO emission limitation; 

and

ii. You have installed a 

CPMS to continuously

monitor operating 

parameters approved by the 

Administrator (if any) 

according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 
71

approved operating 

parameters (if any) during 

the initial performance test.
72

5. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source 

of HAP, new or 

reconstructed nonemergency 4SLB 

stationary RICE ≥250 HP 

located at a major source 

of HAP, non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP.

a. Reduce CO emissions, 

and using a CEMS

i. You have installed a 

CEMS to continuously

monitor CO and either O2 or 

CO2 at both the inlet and 

outlet of the oxidation 

catalyst according to the 

requirements in 

§63.6625(a); and

ii. You have conducted a 

performance evaluation of 

your CEMS using PS 3 and 

4A of 40 CFR part 60, 

appendix B; and

iii. The average reduction of 

CO calculated using 

§63.6620 equals or exceeds 

the required percent 

reduction. The initial test 

comprises the first 4-hour 

period after successful 

validation of the CEMS. 

Compliance is based on the 

average percent reduction 

achieved during the 4-hour 

period.
73

6. Non-emergency

stationary CI RICE >500 

HP located at a major 

source of HAP, and 

existing non-emergency

stationary CI RICE >500 

HP located at an area 

source of HAP.

a. Limit the concentration 

of CO, and using a CEMS

i. You have installed a 

CEMS to continuously

monitor CO and either O2 or 

CO2 at the outlet of the 

oxidation catalyst according 

to the requirements in 

§63.6625(a); and

ii. You have conducted a 

performance evaluation of 

your CEMS using PS 3 and 

4A of 40 CFR part 60, 

appendix B; and

iii. The average 

concentration of CO 

calculated using §63.6620 is 

less than or equal to the CO 

emission limitation. The 

initial test comprises the 

first 4-hour period after 

successful validation of the 

CEMS. Compliance is 

based on the average 

concentration measured 

during the 4-hour period.

7. Non-emergency 4SRB 

stationary RICE >500 HP 

a. Reduce formaldehyde 

emissions and using NSCR

i. The average reduction of 

emissions of formaldehyde 
74

located at a major source 

of HAP.

determined from the initial 

performance test is equal to 

or greater than the required 

formaldehyde percent 

reduction or the average 

reduction of emissions of 

THC determined from the 

initial performance test is 

equal to or greater than 30 

percent; and

ii. You have installed a 

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 

§63.6625(b); and

iii. You have recorded the 

catalyst pressure drop and 

catalyst inlet temperature 

during the initial 

performance test.

8. Non-emergency 4SRB 

stationary RICE >500 HP 

located at a major source of 

HAP.

a. Reduce formaldehyde 

emissions and not using 

NSCR

i. The average reduction of 

emissions of formaldehyde 

determined from the initial 

performance test is equal to 

or greater than the required 

formaldehyde percent 
75

reduction; and

ii. You have installed a 

CPMS to continuously

monitor operating 

parameters approved by the 

Administrator (if any) 

according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 

approved operating 

parameters (if any) during 

the initial performance test.

9. New or reconstructed 

non-emergency stationary

RICE >500 HP located at a 

major source of HAP, new 

or reconstructed nonemergency 4SLB stationary

RICE 250≤HP≤500 located 

at a major source of HAP, 

and existing nonemergency 4SRB 

stationary RICE >500 HP

located at a major source of 

HAP.

a. Limit the concentration of 

formaldehyde in the 

stationary RICE exhaust and 

using oxidation catalyst or 

NSCR

i. The average formaldehyde 

concentration, corrected to 

15 percent O2, dry basis, 

from the three test runs is 

less than or equal to the 

formaldehyde emission 

limitation; and

ii. You have installed a 

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 
76

§63.6625(b); and 

iii. You have recorded the 

catalyst pressure drop and 

catalyst inlet temperature 

during the initial 

performance test.

10. New or reconstructed 

non-emergency stationary

RICE >500 HP located at a 

major source of HAP, new 

or reconstructed nonemergency 4SLB stationary

RICE 250≤HP≤500 located 

at a major source of HAP, 

and existing nonemergency 4SRB 

stationary RICE >500 HP

located at a major source of 

HAP.

a. Limit the concentration of 

formaldehyde in the 

stationary RICE exhaust and 

not using oxidation catalyst 

or NSCR

i. The average formaldehyde 

concentration, corrected to 

15 percent O2, dry basis, 

from the three test runs is 

less than or equal to the 

formaldehyde emission 

limitation; and

ii. You have installed a 

CPMS to continuously

monitor operating 

parameters approved by the 

Administrator (if any) 

according to the 

requirements in 

§63.6625(b); and 

iii. You have recorded the 

approved operating 

parameters (if any) during 

the initial performance test.
77

11. Existing nonemergency stationary RICE 

100≤HP≤500 located at a 

major source of HAP, and 

existing non-emergency

stationary CI RICE 

300<HP≤500 located at an 

area source of HAP. 

a. Reduce CO emissions. i. The average reduction of 

emissions of CO or 

formaldehyde, as applicable 

determined from the initial 

performance test is equal to 

or greater than the required 

CO or formaldehyde, as 

applicable, percent 

reduction.

12. Existing nonemergency stationary RICE 

100≤HP≤500 located at a 

major source of HAP, and 

existing non-emergency

stationary CI RICE 

300<HP≤500 located at an 

area source of HAP. 

a. Limit the concentration of 

formaldehyde or CO in the 

stationary RICE exhaust.

i. The average formaldehyde 

or CO concentration, as 

applicable, corrected to 15 

percent O2, dry basis, from 

the three test runs is less 

than or equal to the 

formaldehyde or CO 

emission limitation, as 

applicable.

13. Existing nonemergency 4SLB stationary

RICE >500 HP located at 

an area source of HAP that 

are not remote stationary

RICE and that are operated 

more than 24 hours per 

calendar year

a. Install an oxidation 

catalyst

i. You have conducted an 

initial compliance 

demonstration as specified 

in §63.6630(e) to show that 

the average reduction of 

emissions of CO is 93 

percent or more, or the 

average CO concentration is 

less than or equal to 47 

ppmvd at 15 percent O2

ii. You have installed a 
78

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 

§63.6625(b), or you have 

installed equipment to 

automatically shut down the 

engine if the catalyst inlet 

temperature exceeds 1350°F

14. Existing nonemergency 4SRB 

stationary RICE >500 HP 

located at an area source of 

HAP that are not remote 

stationary RICE and that 

are operated more than 24 

hours per calendar year

a. Install NSCR i. You have conducted an 

initial compliance 

demonstration as specified 

in §63.6630(e) to show that

the average reduction of 

emissions of CO is 75 

percent or more, or the 

average reduction of 

emissions of THC is 30 

percent or more 

ii. You have installed a 

CPMS to continuously

monitor catalyst inlet 

temperature according to the 

requirements in 

§63.6625(b), or you have 

installed equipment to 

automatically shut down the 

engine if the catalyst inlet 
79

temperature exceeds 1250°F

Table 6 to Subpart ZZZZ of Part 63. Continuous Compliance with Emission Limitations, 

Operating Limitations, Work Practices, and Management Practices

As stated in §63.6640, you must continuously comply with the emissions and operating 

limitations and work or management practices as required by the following:

For each . . . Complying with the 

requirement to . . .

You must demonstrate 

continuous compliance by 

. . .

1. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source of 

HAP, new or reconstructed 

non-emergency 4SLB 

stationary RICE ≥250 HP 

located at a major source of 

HAP, and new or 

reconstructed nonemergency CI stationary

RICE >500 HP located at a 

major source of HAP.

a. Reduce CO emissions and 

using an oxidation catalyst, 

and using a CPMS

i. Conducting semiannual 

performance tests for CO to 

demonstrate that the 

required CO percent 

reduction is achieveda; and

ii. Collecting the catalyst 

inlet temperature data 

according to §63.6625(b); 

and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 
80

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; 

and 

v. Measuring the pressure 

drop across the catalyst once 

per month and 

demonstrating that the 

pressure drop across the 

catalyst is within the 

operating limitation 

established during the 

performance test.

2. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source of 

HAP, new or reconstructed 

non-emergency 4SLB 

stationary RICE ≥250 HP 

located at a major source of 

HAP, and new or 

reconstructed nonemergency CI stationary

RICE >500 HP located at a 

major source of HAP.

a. Reduce CO emissions and 

not using an oxidation 

catalyst, and using a CPMS

i. Conducting semiannual 

performance tests for CO to 

demonstrate that the 

required CO percent 

reduction is achieveda; and

ii. Collecting the approved 

operating parameter (if any) 

data according to 

§63.6625(b); and

iii. Reducing these data to 4-

hour rolling averages; and
81

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

operating parameters 

established during the 

performance test.

3. New or reconstructed 

non-emergency 2SLB 

stationary RICE >500 HP 

located at a major source of 

HAP, new or reconstructed 

non-emergency 4SLB 

stationary RICE ≥250 HP 

located at a major source of 

HAP, new or reconstructed 

non-emergency stationary

CI RICE >500 HP located 

at a major source of HAP, 

and existing nonemergency stationary CI 

RICE >500 HP.

a. Reduce CO emissions or 

limit the concentration of 

CO in the stationary RICE 

exhaust, and using a CEMS

i. Collecting the monitoring 

data according to 

§63.6625(a), reducing the 

measurements to 1-hour 

averages, calculating the 

percent reduction or 

concentration of CO 

emissions according to 

§63.6620; and 

ii. Demonstrating that the 

catalyst achieves the 

required percent reduction 

of CO emissions over the 4-

hour averaging period, or 

that the emission remain at 

or below the CO 

concentration limit; and

iii. Conducting an annual 

RATA of your CEMS using 
82

PS 3 and 4A of 40 CFR part 

60, appendix B, as well as 

daily and periodic data 

quality checks in 

accordance with 40 CFR 

part 60, appendix F, 

procedure 1.

4. Non-emergency 4SRB 

stationary RICE >500 HP 

located at a major source of 

HAP.

a. Reduce formaldehyde 

emissions and using NSCR

i. Collecting the catalyst 

inlet temperature data 

according to §63.6625(b); 

and

ii. reducing these data to 4-

hour rolling averages; and

iii. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; 

and 

iv. Measuring the pressure 

drop across the catalyst once 

per month and 

demonstrating that the 

pressure drop across the 

catalyst is within the 

operating limitation 
83

established during the 

performance test.

5. Non-emergency 4SRB 

stationary RICE >500 HP 

located at a major source of 

HAP.

a. Reduce formaldehyde 

emissions and not using 

NSCR

i. Collecting the approved 

operating parameter (if any) 

data according to 

§63.6625(b); and

ii. Reducing these data to 4-

hour rolling averages; and

iii. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

operating parameters 

established during the 

performance test.

6. Non-emergency 4SRB 

stationary RICE with a 

brake HP ≥5,000 located at 

a major source of HAP.

a. Reduce formaldehyde 

emissions

Conducting semiannual 

performance tests for 

formaldehyde to 

demonstrate that the 

required formaldehyde 

percent reduction is 

achieved, or to demonstrate 

that the average reduction of 

emissions of THC 

determined from the 

performance test is equal to 

or greater than 30 percent.a
84

7. New or reconstructed 

non-emergency stationary

RICE >500 HP located at a 

major source of HAP and 

new or reconstructed nonemergency 4SLB stationary

RICE 250≤HP≤500 located 

at a major source of HAP.

a. Limit the concentration of 

formaldehyde in the 

stationary RICE exhaust and 

using oxidation catalyst or 

NSCR

i. Conducting semiannual 

performance tests for 

formaldehyde to 

demonstrate that your 

emissions remain at or 

below the formaldehyde 

concentration limita; and

ii. Collecting the catalyst 

inlet temperature data 

according to §63.6625(b); 

and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; 

and 

v. Measuring the pressure 

drop across the catalyst once 

per month and 

demonstrating that the 

pressure drop across the 
85

catalyst is within the 

operating limitation 

established during the 

performance test.

8. New or reconstructed 

non-emergency stationary

RICE >500 HP located at a 

major source of HAP and 

new or reconstructed nonemergency 4SLB stationary 

RICE 250≤HP≤500 located 

at a major source of HAP.

a. Limit the concentration of 

formaldehyde in the 

stationary RICE exhaust and 

not using oxidation catalyst 

or NSCR

i. Conducting semiannual 

performance tests for 

formaldehyde to 

demonstrate that your 

emissions remain at or 

below the formaldehyde 

concentration limita; and

ii. Collecting the approved 

operating parameter (if any) 

data according to 

§63.6625(b); and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

operating parameters 

established during the 

performance test.

9. Existing emergency and 

black start stationary RICE 

a. Work or Management i. Operating and maintaining 

the stationary RICE 
86

≤500 HP located at a major 

source of HAP, existing 

non-emergency stationary

RICE <100 HP located at a 

major source of HAP, 

existing emergency and 

black start stationary RICE 

located at an area source of 

HAP, existing nonemergency stationary CI 

RICE ≤300 HP located at 

an area source of HAP, 

existing non-emergency

2SLB stationary RICE 

located at an area source of 

HAP, existing nonemergency stationary SI 

RICE located at an area 

source of HAP which 

combusts landfill or 

digester gas equivalent to 

10 percent or more of the 

gross heat input on an 

annual basis, existing nonemergency 4SLB and 

4SRB stationary RICE 

≤500 HP located at an area 

source of HAP, existing 

non-emergency 4SLB and 

4SRB stationary RICE 

>500 HP located at an area 

practices. according to the 

manufacturer’s emissionrelated operation and 

maintenance instructions;

or

ii. Develop and follow your 

own maintenance plan 

which must provide to the 

extent practicable for the 

maintenance and operation 

of the engine in a manner 

consistent with good air 

pollution control practice 

for minimizing emissions.
87

source of HAP that operate 

24 hours or less per 

calendar year, and existing 

non-emergency 4SLB and 

4SRB stationary RICE 

>500 HP located at an area 

source of HAP that are 

remote stationary RICE.

10. Existing stationary CI 

RICE >500 HP that are not 

limited use stationary

RICE.

a. Reduce CO emissions, or 

limit the concentration of 

CO in the stationary RICE 

exhaust, and using oxidation 

catalyst

i. Conducting performance 

tests every 8,760 hours or 3 

years, whichever comes 

first, for CO or 

formaldehyde, as 

appropriate, to demonstrate 

that the required CO or 

formaldehyde, as 

appropriate, percent 

reduction is achieved or that 

your emissions remain at or 

below the CO or 

formaldehyde concentration 

limit; and

ii. Collecting the catalyst 

inlet temperature data 

according to §63.6625(b); 

and

iii. Reducing these data to 4-

hour rolling averages; and
88

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; 

and 

v. Measuring the pressure 

drop across the catalyst once 

per month and 

demonstrating that the 

pressure drop across the 

catalyst is within the 

operating limitation 

established during the 

performance test.

11. Existing stationary CI 

RICE >500 HP that are not 

limited use stationary

RICE.

a. Reduce CO emissions, or 

limit the concentration of 

CO in the stationary RICE 

exhaust, and not using 

oxidation catalyst

i. Conducting performance 

tests every 8,760 hours or 3 

years, whichever comes 

first, for CO or 

formaldehyde, as 

appropriate, to demonstrate 

that the required CO or 

formaldehyde, as 

appropriate, percent 

reduction is achieved or that 

your emissions remain at or 

below the CO or 

formaldehyde concentration 

limit; and
89

ii. Collecting the approved 

operating parameter (if any) 

data according to 

§63.6625(b); and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

operating parameters 

established during the 

performance test.

12. Existing limited use CI

stationary RICE >500 HP.

a. Reduce CO emissions or 

limit the concentration of 

CO in the stationary RICE 

exhaust, and using an 

oxidation catalyst

i. Conducting performance 

tests every 8,760 hours or 5 

years, whichever comes 

first, for CO or 

formaldehyde, as 

appropriate, to demonstrate 

that the required CO or 

formaldehyde, as 

appropriate, percent 

reduction is achieved or

that your emissions remain 

at or below the CO or 

formaldehyde concentration 

limit; and 

ii. Collecting the catalyst 

inlet temperature data 
90

according to §63.6625(b); 

and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; 

and 

v. Measuring the pressure 

drop across the catalyst once 

per month and 

demonstrating that the 

pressure drop across the 

catalyst is within the 

operating limitation 

established during the 

performance test.

13. Existing limited use CI

stationary RICE >500 HP.

a. Reduce CO emissions or 

limit the concentration of 

CO in the stationary RICE 

exhaust, and not using an 

oxidation catalyst

i. Conducting performance 

tests every 8,760 hours or 5 

years, whichever comes 

first, for CO or 

formaldehyde, as 

appropriate, to demonstrate 

that the required CO or 

formaldehyde, as 

appropriate, percent 

reduction is achieved or
91

that your emissions remain 

at or below the CO or 

formaldehyde concentration 

limit; and 

ii. Collecting the approved 

operating parameter (if any) 

data according to 

§63.6625(b); and

iii. Reducing these data to 4-

hour rolling averages; and

iv. Maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

operating parameters 

established during the 

performance test.

14. Existing nonemergency 4SLB stationary

RICE >500 HP located at 

an area source of HAP that 

are not remote stationary

RICE and that are operated 

more than 24 hours per 

calendar year

a. Install an oxidation 

catalyst

i. Conducting annual 

compliance demonstrations 

as specified in §63.6640(c) 

to show that the average 

reduction of emissions of 

CO is 93 percent or more, or 

the average CO 

concentration is less than or 

equal to 47 ppmvd at 15 

percent O2; and either

ii. Collecting the catalyst 

inlet temperature data 
92

according to §63.6625(b), 

reducing these data to 4-

hour rolling averages; and 

maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; or

iii. Immediately shutting

down the engine if the 

catalyst inlet temperature 

exceeds 1350°F.

15. Existing nonemergency 4SRB 

stationary RICE >500 HP 

located at an area source of 

HAP that are not remote 

stationary RICE and that 

are operated more than 24 

hours per calendar year

a. Install NSCR i. Conducting annual 

compliance demonstrations 

as specified in §63.6640(c) 

to show that the average 

reduction of emissions of 

CO is 75 percent or more, or 

the average reduction of 

emissions of THC is 30 

percent or more; and either

ii. Collecting the catalyst 

inlet temperature data 

according to §63.6625(b), 

reducing these data to 4-

hour rolling averages; and 

maintaining the 4-hour 

rolling averages within the 

operating limitations for the 

catalyst inlet temperature; or
93

iii. Immediately shutting 

down the engine if the 

catalyst inlet temperature 

exceeds 1250° F.

aAfter you have demonstrated compliance for two consecutive tests, you may reduce the 

frequency of subsequent performance tests to annually. If the results of any subsequent annual 

performance test indicate the stationary RICE is not in compliance with the CO or formaldehyde 

emission limitation, or you deviate from any of your operating limitations, you must resume 

semiannual performance tests.

Table 7 to Subpart ZZZZ of Part 63. Requirements for Reports

As stated in §63.6650, you must comply with the following requirements for reports:

For each . . . You must submit a 

. . .

The report must 

contain . . .

You must submit the 

report . . .

1. Existing nonemergency, nonblack start 

stationary RICE 

100≤HP≤500 

located at a major 

source of HAP; 

existing nonemergency, nonblack start 

stationary CI RICE 

>500 HP located at 

a major source of 

HAP; existing nonCompliance report a. If there are no 

deviations from any 

emission limitations or 

operating limitations that 

apply to you, a statement 

that there were no 

deviations from the 

emission limitations or 

operating limitations 

during the reporting 

period. If there were no 

periods during which the 

CMS, including CEMS 

and CPMS, was out-ofi. Semiannually

according to the 

requirements in 

§63.6650(b)(1)-(5) for 

engines that are not 

limited use stationary

RICE subject to 

numerical emission 

limitations; and

ii. Annually according to 

the requirements in 

§63.6650(b)(6)-(9) for 

engines that are limited 

use stationary RICE 
94

emergency 4SRB 

stationary RICE 

>500 HP located at 

a major source of 

HAP; existing nonemergency, nonblack start 

stationary CI RICE 

>300 HP located at 

an area source of 

HAP; new or 

reconstructed nonemergency

stationary RICE 

>500 HP located at 

a major source of 

HAP; and new or 

reconstructed nonemergency 4SLB 

stationary RICE 

250≤HP≤500 

located at a major 

source of HAP 

control, as specified in 

§63.8(c)(7), a statement 

that there were not 

periods during which the 

CMS was out-of-control 

during the reporting 

period; or

subject to numerical 

emission limitations.

b. If you had a deviation 

from any emission 

limitation or operating 

limitation during the 

reporting period, the 

information in 

§63.6650(d). If there 

were periods during 

which the CMS, 

including CEMS and 

CPMS, was out-ofcontrol, as specified in 

§63.8(c)(7), the 

information in 

§63.6650(e); or

i. Semiannually

according to the 

requirements in 

§63.6650(b).

c. If you had a 

malfunction during the 

reporting period, the 

information in 

§63.6650(c)(4).

i. Semiannually

according to the 

requirements in 

§63.6650(b).

2. New or 

reconstructed nonemergency

Report a. The fuel flow rate of 

each fuel and the heating 

values that were used in 

i. Annually, according to 

the requirements in 

§63.6650.
95

stationary RICE 

that combusts 

landfill gas or 

digester gas 

equivalent to 10 

percent or more of 

the gross heat 

input on an annual 

basis

your calculations, and 

you must demonstrate 

that the percentage of 

heat input provided by

landfill gas or digester 

gas, is equivalent to 10 

percent or more of the 

gross heat input on an 

annual basis; and

b. The operating limits 

provided in your 

federally enforceable 

permit, and any 

deviations from these 

limits; and

i. See item 2.a.i.

c. Any problems or 

errors suspected with the 

meters.

i. See item 2.a.i.

3. Existing nonemergency, nonblack start 4SLB 

and 4SRB 

stationary RICE 

>500 HP located at 

an area source of 

HAP that are not 

remote stationary

RICE and that 

operate more than 

24 hours per 

Compliance report a. The results of the 

annual compliance 

demonstration, if 

conducted during the 

reporting period. 

i. Semiannually

according to the 

requirements in 

§63.6650(b)(1)-(5)
96

calendar year

Table 8 to Subpart ZZZZ of Part 63—Applicability of General Provisions to Subpart 

ZZZZ.

As stated in §63.6665, you must comply with the following applicable general provisions.

General 

provisions 

citation Subject of citation

Applies to 

subpart Explanation

§63.1 General applicability of the 

General Provisions

Yes.

§63.2 Definitions Yes Additional terms defined in 

§63.6675.

§63.3 Units and abbreviations Yes.

§63.4 Prohibited activities and 

circumvention

Yes.

§63.5 Construction and 

reconstruction

Yes.

§63.6(a) Applicability Yes.

§63.6(b)(1)–(4) Compliance dates for new and 

reconstructed sources

Yes.

§63.6(b)(5) Notification Yes.
97

§63.6(b)(6) [Reserved]

§63.6(b)(7) Compliance dates for new and 

reconstructed area sources that 

become major sources

Yes.

§63.6(c)(1)–(2) Compliance dates for existing 

sources

Yes.

§63.6(c)(3)–(4) [Reserved]

§63.6(c)(5) Compliance dates for existing 

area sources that become 

major sources

Yes.

§63.6(d) [Reserved]

§63.6(e) Operation and maintenance No.

§63.6(f)(1) Applicability of standards No.

§63.6(f)(2) Methods for determining 

compliance

Yes.

§63.6(f)(3) Finding of compliance Yes.

§63.6(g)(1)–(3) Use of alternate standard Yes.

§63.6(h) Opacity and visible emission 

standards

No Subpart ZZZZ does not 

contain opacity or visible 

emission standards.
98

§63.6(i) Compliance extension 

procedures and criteria

Yes.

§63.6(j) Presidential compliance 

exemption

Yes.

§63.7(a)(1)–(2) Performance test dates Yes Subpart ZZZZ contains 

performance test dates at 

§§63.6610, 63.6611, and 

63.6612.

§63.7(a)(3) CAA section 114 authority Yes.

§63.7(b)(1) Notification of performance 

test

Yes Except that §63.7(b)(1) only

applies as specified in 

§63.6645.

§63.7(b)(2) Notification of rescheduling Yes Except that §63.7(b)(2) only

applies as specified in 

§63.6645.

§63.7(c) Quality assurance/test plan Yes Except that §63.7(c) only 

applies as specified in 

§63.6645.

§63.7(d) Testing facilities Yes.

§63.7(e)(1) Conditions for conducting 

performance tests

No. Subpart ZZZZ specifies 

conditions for conducting 

performance tests at 

§63.6620.
99

§63.7(e)(2) Conduct of performance tests 

and reduction of data

Yes Subpart ZZZZ specifies test 

methods at §63.6620.

§63.7(e)(3) Test run duration Yes.

§63.7(e)(4) Administrator may require 

other testing under section 114 

of the CAA

Yes.

§63.7(f) Alternative test method 

provisions

Yes.

§63.7(g) Performance test data analysis, 

recordkeeping, and reporting

Yes.

§63.7(h) Waiver of tests Yes.

§63.8(a)(1) Applicability of monitoring 

requirements

Yes Subpart ZZZZ contains 

specific requirements for 

monitoring at §63.6625.

§63.8(a)(2) Performance specifications Yes.

§63.8(a)(3) [Reserved]

§63.8(a)(4) Monitoring for control devices No.

§63.8(b)(1) Monitoring Yes.

§63.8(b)(2)–(3) Multiple effluents and multiple 

monitoring systems

Yes.
100

§63.8(c)(1) Monitoring system operation 

and maintenance

Yes.

§63.8(c)(1)(i) Routine and predictable SSM Yes.

§63.8(c)(1)(ii) SSM not in Startup Shutdown 

Malfunction Plan

Yes.

§63.8(c)(1)(iii) Compliance with operation 

and maintenance requirements

Yes.

§63.8(c)(2)–(3) Monitoring system installation Yes.

§63.8(c)(4) Continuous monitoring system 

(CMS) requirements

Yes Except that subpart ZZZZ 

does not require Continuous 

Opacity Monitoring System 

(COMS).

§63.8(c)(5) COMS minimum procedures No Subpart ZZZZ does not 

require COMS.

§63.8(c)(6)–(8) CMS requirements Yes Except that subpart ZZZZ 

does not require COMS.

§63.8(d) CMS quality control Yes.

§63.8(e) CMS performance evaluation Yes Except for §63.8(e)(5)(ii), 

which applies to COMS.

 Except that 

§63.8(e) only 

applies as 
101

specified in 

§63.6645.

§63.8(f)(1)–(5) Alternative monitoring method Yes Except that §63.8(f)(4) only

applies as specified in 

§63.6645.

§63.8(f)(6) Alternative to relative 

accuracy test

Yes Except that §63.8(f)(6) only

applies as specified in 

§63.6645.

§63.8(g) Data reduction Yes Except that provisions for 

COMS are not applicable. 

Averaging periods for 

demonstrating compliance are 

specified at §§63.6635 and 

63.6640.

§63.9(a) Applicability and State 

delegation of notification 

requirements

Yes.

§63.9(b)(1)–(5) Initial notifications Yes Except that §63.9(b)(3) is 

reserved.

 Except that 

§63.9(b) only

applies as 

specified in 

§63.6645.
102

§63.9(c) Request for compliance 

extension

Yes Except that §63.9(c) only 

applies as specified in 

§63.6645.

§63.9(d) Notification of special 

compliance requirements for 

new sources

Yes Except that §63.9(d) only 

applies as specified in 

§63.6645.

§63.9(e) Notification of performance 

test

Yes Except that §63.9(e) only 

applies as specified in 

§63.6645.

§63.9(f) Notification of visible 

emission (VE)/opacity test

No Subpart ZZZZ does not 

contain opacity or VE 

standards.

§63.9(g)(1) Notification of performance 

evaluation

Yes Except that §63.9(g) only 

applies as specified in 

§63.6645.

§63.9(g)(2) Notification of use of COMS 

data

No Subpart ZZZZ does not 

contain opacity or VE 

standards.

§63.9(g)(3) Notification that criterion for 

alternative to RATA is 

exceeded

Yes If alternative is in use.

 Except that 

§63.9(g) only

applies as 
103

specified in 

§63.6645.

§63.9(h)(1)–(6) Notification of compliance 

status

Yes Except that notifications for 

sources using a CEMS are 

due 30 days after completion 

of performance evaluations. 

§63.9(h)(4) is reserved.

 Except that §63.9(h) only 

applies as specified in 

§63.6645.

§63.9(i) Adjustment of submittal 

deadlines

Yes.

§63.9(j) Change in previous 

information

Yes.

§63.10(a) Administrative provisions for 

recordkeeping/reporting

Yes.

§63.10(b)(1) Record retention Yes.

§63.10(b)(2)(i)–

(v)

Records related to SSM No.

§63.10(b)(2)(vi)–

(xi)

Records Yes.

§63.10(b)(2)(xii) Record when under waiver Yes.
104

§63.10(b)(2)(xiii) Records when using 

alternative to RATA

Yes For CO standard if using 

RATA alternative.

§63.10(b)(2)(xiv) Records of supporting 

documentation

Yes.

§63.10(b)(3) Records of applicability

determination

Yes.

§63.10(c) Additional records for sources 

using CEMS

Yes Except that §63.10(c)(2)–(4) 

and (9) are reserved.

§63.10(d)(1) General reporting 

requirements

Yes.

§63.10(d)(2) Report of performance test 

results

Yes.

§63.10(d)(3) Reporting opacity or VE 

observations

No Subpart ZZZZ does not 

contain opacity or VE 

standards.

§63.10(d)(4) Progress reports Yes.

§63.10(d)(5) Startup, shutdown, and 

malfunction reports

No.

§63.10(e)(1) and 

(2)(i)

Additional CMS Reports Yes.

§63.10(e)(2)(ii) COMS-related report No Subpart ZZZZ does not 
105

require COMS.

§63.10(e)(3) Excess emission and parameter 

exceedances reports

Yes. Except that §63.10(e)(3)(i) 

(C) is reserved.

§63.10(e)(4) Reporting COMS data No Subpart ZZZZ does not 

require COMS.

§63.10(f) Waiver for 

recordkeeping/reporting

Yes.

§63.11 Flares No.

§63.12 State authority and delegations Yes.

§63.13 Addresses Yes.

§63.14 Incorporation by reference Yes.

§63.15 Availability of information Yes.

Appendix A

Protocol for Using an Electrochemical Analyzer to Determine Oxygen and Carbon 

Monoxide Concentrations from Certain Engines 

1.0 Scope and Application. What is this Protocol?

This protocol is a procedure for using portable electrochemical (EC) cells for measuring carbon 

monoxide (CO) and oxygen (O2) concentrations in controlled and uncontrolled emissions from 
106

existing stationary 4-stroke lean burn and 4-stroke rich burn reciprocating internal combustion 

engines as specified in the applicable rule. 

1.1 Analytes. What does this protocol determine? 

This protocol measures the engine exhaust gas concentrations of carbon monoxide (CO) and 

oxygen (O2).

Analyte CAS No. Sensitivity

Carbon monoxide (CO) 630-08-0 Minimum detectable limit 

should be 2 percent of the 

nominal range or 1 ppm, 

whichever is less restrictive.

Oxygen (O2) 7782-44-7

1.2 Applicability. When is this protocol acceptable?

This protocol is applicable to 40 CFR part 63, subpart ZZZZ. Because of inherent cross 

sensitivities of EC cells, you must not apply this protocol to other emissions sources without 

specific instruction to that effect.

1.3 Data Quality Objectives. How good must my collected data be? 

Refer to Section 13 to verify and document acceptable analyzer performance.

1.4 Range. What is the targeted analytical range for this protocol?

The measurement system and EC cell design(s) conforming to this protocol will determine the 

analytical range for each gas component. The nominal ranges are defined by choosing up-scale 

calibration gas concentrations near the maximum anticipated flue gas concentrations for CO and 

O2, or no more than twice the permitted CO level.

1.5 Sensitivity. What minimum detectable limit will this protocol yield for a particular gas 

component?
107

The minimum detectable limit depends on the nominal range and resolution of the specific EC 

cell used, and the signal to noise ratio of the measurement system. The minimum detectable limit 

should be 2 percent of the nominal range or 1 ppm, whichever is less restrictive.

2.0 Summary of Protocol

In this protocol, a gas sample is extracted from an engine exhaust system and then conveyed to a 

portable EC analyzer for measurement of CO and O2 gas concentrations. This method provides 

measurement system performance specifications and sampling protocols to ensure reliable data. 

You may use additions to, or modifications of vendor supplied measurement systems (e.g., 

heated or unheated sample lines, thermocouples, flow meters, selective gas scrubbers, etc.) to 

meet the design specifications of this protocol. Do not make changes to the measurement system 

from the as-verified configuration (Section 3.12).

3.0 Definitions 

3.1 Measurement System. The total equipment required for the measurement of CO and O2

concentrations. The measurement system consists of the following major subsystems:

3.1.1 Data Recorder. A strip chart recorder, computer or digital recorder for logging 

measurement data from the analyzer output. You may record measurement data from the digital 

data display manually or electronically.

3.1.2 Electrochemical (EC) Cell. A device, similar to a fuel cell, used to sense the presence of a 

specific analyte and generate an electrical current output proportional to the analyte 

concentration.

3.1.3 Interference Gas Scrubber. A device used to remove or neutralize chemical compounds 

that may interfere with the selective operation of an EC cell.

3.1.4 Moisture Removal System. Any device used to reduce the concentration of moisture in the 

sample stream so as to protect the EC cells from the damaging effects of condensation and to 

minimize errors in measurements caused by the scrubbing of soluble gases.

3.1.5 Sample Interface. The portion of the system used for one or more of the following: sample 

acquisition; sample transport; sample conditioning or protection of the EC cell from any 
108

degrading effects of the engine exhaust effluent; removal of particulate matter and condensed 

moisture.

3.2 Nominal Range. The range of analyte concentrations over which each EC cell is operated 

(normally 25 percent to 150 percent of up-scale calibration gas value). Several nominal ranges 

can be used for any given cell so long as the calibration and repeatability checks for that range 

remain within specifications.

3.3 Calibration Gas. A vendor certified concentration of a specific analyte in an appropriate 

balance gas.

3.4 Zero Calibration Error. The analyte concentration output exhibited by the EC cell in 

response to zero-level calibration gas.

3.5 Up-Scale Calibration Error. The mean of the difference between the analyte concentration 

exhibited by the EC cell and the certified concentration of the up-scale calibration gas.

3.6 Interference Check. A procedure for quantifying analytical interference from components in 

the engine exhaust gas other than the targeted analytes.

3.7 Repeatability Check. A protocol for demonstrating that an EC cell operated over a given 

nominal analyte concentration range provides a stable and consistent response and is not 

significantly affected by repeated exposure to that gas.

3.8 Sample Flow Rate. The flow rate of the gas sample as it passes through the EC cell. In some 

situations, EC cells can experience drift with changes in flow rate. The flow rate must be 

monitored and documented during all phases of a sampling run.

3.9 Sampling Run. A timed three-phase event whereby an EC cell’s response rises and plateaus 

in a sample conditioning phase, remains relatively constant during a measurement data phase, 

then declines during a refresh phase. The sample conditioning phase exposes the EC cell to the 

gas sample for a length of time sufficient to reach a constant response. The measurement data 

phase is the time interval during which gas sample measurements can be made that meet the 

acceptance criteria of this protocol. The refresh phase then purges the EC cells with CO-free air. 

The refresh phase replenishes requisite O2 and moisture in the electrolyte reserve and provides a 
109

mechanism to de-gas or desorb any interference gas scrubbers or filters so as to enable a stable 

CO EC cell response. There are four primary types of sampling runs: pre- sampling calibrations; 

stack gas sampling; post-sampling calibration checks; and measurement system repeatability

checks. Stack gas sampling runs can be chained together for extended evaluations, providing all 

other procedural specifications are met.

3.10 Sampling Day. A time not to exceed twelve hours from the time of the pre-sampling 

calibration to the post-sampling calibration check. During this time, stack gas sampling runs can 

be repeated without repeated recalibrations, providing all other sampling specifications have 

been met.

3.11 Pre-Sampling Calibration/Post-Sampling Calibration Check. The protocols executed at the 

beginning and end of each sampling day to bracket measurement readings with controlled 

performance checks.

3.12 Performance-Established Configuration. The EC cell and sampling system configuration 

that existed at the time that it initially met the performance requirements of this protocol.

4.0 Interferences.

When present in sufficient concentrations, NO and NO2 are two gas species that have been 

reported to interfere with CO concentration measurements. In the likelihood of this occurrence, it 

is the protocol user’s responsibility to employ and properly maintain an appropriate CO EC cell 

filter or scrubber for removal of these gases, as described in Section 6.2.12.

5.0 Safety. [Reserved]

6.0 Equipment and Supplies.

6.1 What equipment do I need for the measurement system?

The system must maintain the gas sample at conditions that will prevent moisture condensation 

in the sample transport lines, both before and as the sample gas contacts the EC cells. The 

essential components of the measurement system are described below.

6.2 Measurement System Components. 
110

6.2.1 Sample Probe. A single extraction-point probe constructed of glass, stainless steel or other 

non-reactive material, and of length sufficient to reach any designated sampling point. The 

sample probe must be designed to prevent plugging due to condensation or particulate matter.

6.2.2 Sample Line. Non-reactive tubing to transport the effluent from the sample probe to the EC 

cell.

6.2.3 Calibration Assembly (optional). A three-way valve assembly or equivalent to introduce 

calibration gases at ambient pressure at the exit end of the sample probe during calibration 

checks. The assembly must be designed such that only stack gas or calibration gas flows in the 

sample line and all gases flow through any gas path filters.

6.2.4 Particulate Filter (optional). Filters before the inlet of the EC cell to prevent accumulation 

of particulate material in the measurement system and extend the useful life of the components. 

All filters must be fabricated of materials that are non-reactive to the gas mixtures being 

sampled.

6.2.5 Sample Pump. A leak-free pump to provide undiluted sample gas to the system at a flow 

rate sufficient to minimize the response time of the measurement system. If located upstream of 

the EC cells, the pump must be constructed of a material that is non-reactive to the gas mixtures 

being sampled.

6.2.8 Sample Flow Rate Monitoring. An adjustable rotameter or equivalent device used to adjust 

and maintain the sample flow rate through the analyzer as prescribed.

6.2.9 Sample Gas Manifold (optional). A manifold to divert a portion of the sample gas stream to 

the analyzer and the remainder to a by-pass discharge vent. The sample gas manifold may also 

include provisions for introducing calibration gases directly to the analyzer. The manifold must 

be constructed of a material that is non-reactive to the gas mixtures being sampled.

6.2.10 EC cell. A device containing one or more EC cells to determine the CO and O2

concentrations in the sample gas stream. The EC cell(s) must meet the applicable performance 

specifications of Section 13 of this protocol. 
111

6.2.11 Data Recorder. A strip chart recorder, computer or digital recorder to make a record of 

analyzer output data. The data recorder resolution (i.e., readability) must be no greater than 1 

ppm for CO; 0.1 percent for O2; and one degree (either oC or oF) for temperature. Alternatively, 

you may use a digital or analog meter having the same resolution to observe and manually record 

the analyzer responses.

6.2.12 Interference Gas Filter or Scrubber. A device to remove interfering compounds upstream 

of the CO EC cell. Specific interference gas filters or scrubbers used in the performanceestablished configuration of the analyzer must continue to be used. Such a filter or scrubber must 

have a means to determine when the removal agent is exhausted. Periodically replace or 

replenish it in accordance with the manufacturer’s recommendations.

7.0 Reagents and Standards. What calibration gases are needed?

7.1 Calibration Gases. CO calibration gases for the EC cell must be CO in nitrogen or CO in a 

mixture of nitrogen and O2. Use CO calibration gases with labeled concentration values certified 

by the manufacturer to be within ± 5 percent of the label value. Dry ambient air (20.9 percent O2) 

is acceptable for calibration of the O2 cell. If needed, any lower percentage O2 calibration gas 

must be a mixture of O2 in nitrogen.

7.1.1 Up-Scale CO Calibration Gas Concentration.

Choose one or more up-scale gas concentrations such that the average of the stack gas 

measurements for each stack gas sampling run are between 25 and 150 percent of those 

concentrations. Alternatively, choose an up-scale gas that does not exceed twice the 

concentration of the applicable outlet standard. If a measured gas value exceeds 150 percent of 

the up-scale CO calibration gas value at any time during the stack gas sampling run, the run must 

be discarded and repeated.

7.1.2 Up-Scale O2 Calibration Gas Concentration.

Select an O2 gas concentration such that the difference between the gas concentration and the 

average stack gas measurement or reading for each sample run is less than 15 percent O2. When 

the average exhaust gas O2 readings are above 6 percent, you may use dry ambient air (20.9 

percent O2) for the up-scale O2 calibration gas.
112

7.1.3 Zero Gas. Use an inert gas that contains less than 0.25 percent of the up-scale CO 

calibration gas concentration. You may use dry air that is free from ambient CO and other 

combustion gas products (e.g., CO2).

8.0 Sample Collection and Analysis

8.1 Selection of Sampling Sites.

8.1.1 Control Device Inlet. Select a sampling site sufficiently downstream of the engine so that 

the combustion gases should be well mixed. Use a single sampling extraction point near the 

center of the duct (e.g., within the 10 percent centroidal area), unless instructed otherwise.

8.1.2 Exhaust Gas Outlet. Select a sampling site located at least two stack diameters downstream 

of any disturbance (e.g., turbocharger exhaust, crossover junction or recirculation take-off) and at 

least one-half stack diameter upstream of the gas discharge to the atmosphere. Use a single 

sampling extraction point near the center of the duct (e.g., within the 10 percent centroidal area), 

unless instructed otherwise.

8.2 Stack Gas Collection and Analysis. Prior to the first stack gas sampling run, conduct that the 

pre-sampling calibration in accordance with Section 10.1. Use Figure 1 to record all data. Zero 

the analyzer with zero gas. Confirm and record that the scrubber media color is correct and not 

exhausted. Then position the probe at the sampling point and begin the sampling run at the same 

flow rate used during the up-scale calibration. Record the start time. Record all EC cell output 

responses and the flow rate during the “sample conditioning phase” once per minute until 

constant readings are obtained. Then begin the “measurement data phase” and record readings 

every 15 seconds for at least two minutes (or eight readings), or as otherwise required to achieve 

two continuous minutes of data that meet the specification given in Section 13.1. Finally, 

perform the “refresh phase” by introducing dry air, free from CO and other combustion gases, 

until several minute-to-minute readings of consistent value have been obtained. For each run use 

the “measurement data phase” readings to calculate the average stack gas CO and O2

concentrations.

8.3 EC Cell Rate. Maintain the EC cell sample flow rate so that it does not vary by more than ± 

10 percent throughout the pre-sampling calibration, stack gas sampling and post-sampling 
113

calibration check. Alternatively, the EC cell sample flow rate can be maintained within a 

tolerance range that does not affect the gas concentration readings by more than ± 3 percent, as 

instructed by the EC cell manufacturer. 

9.0 Quality Control (Reserved)

10.0 Calibration and Standardization 

10.1 Pre-Sampling Calibration. Conduct the following protocol once for each nominal range to 

be used on each EC cell before performing a stack gas sampling run on each field sampling day. 

Repeat the calibration if you replace an EC cell before completing all of the sampling runs. 

There is no prescribed order for calibration of the EC cells; however, each cell must complete the 

measurement data phase during calibration. Assemble the measurement system by following the 

manufacturer's recommended protocols including for preparing and preconditioning the EC cell. 

Assure the measurement system has no leaks and verify the gas scrubbing agent is not depleted. 

Use Figure 1 to record all data.

10.1.1 Zero Calibration. For both the O2 and CO cells, introduce zero gas to the measurement 

system (e.g., at the calibration assembly) and record the concentration reading every minute until 

readings are constant for at least two consecutive minutes. Include the time and sample flow rate. 

Repeat the steps in this section at least once to verify the zero calibration for each component 

gas.

10.1.2 Zero Calibration Tolerance. For each zero gas introduction, the zero level output must be 

less than or equal to ± 3 percent of the up-scale gas value or ± 1 ppm, whichever is less 

restrictive, for the CO channel and less than or equal to ± 0.3 percent O2 for the O2 channel.

10.1.3 Up-Scale Calibration. Individually introduce each calibration gas to the measurement 

system (e.g., at the calibration assembly) and record the start time. Record all EC cell output 

responses and the flow rate during this “sample conditioning phase” once per minute until 

readings are constant for at least two minutes. Then begin the “measurement data phase” and 

record readings every 15 seconds for a total of two minutes, or as otherwise required. Finally, 

perform the “refresh phase” by introducing dry air, free from CO and other combustion gases, 

until readings are constant for at least two consecutive minutes. Then repeat the steps in this 
114

section at least once to verify the calibration for each component gas. Introduce all gases to flow 

through the entire sample handling system (i.e., at the exit end of the sampling probe or the 

calibration assembly).

10.1.4 Up-Scale Calibration Error. The mean of the difference of the “measurement data phase” 

readings from the reported standard gas value must be less than or equal to ± 5 percent or ± 1 

ppm for CO or ± 0.5 percent O2, whichever is less restrictive, respectively. The maximum 

allowable deviation from the mean measured value of any single "measurement data phase" 

reading must be less than or equal to ± 2 percent or ± 1 ppm for CO or 

± 0.5 percent O2, whichever is less restrictive, respectively. 

10.2 Post-Sampling Calibration Check. Conduct a stack gas post-sampling calibration check 

after the stack gas sampling run or set of runs and within 12 hours of the initial calibration. 

Conduct up-scale and zero calibration checks using the protocol in Section 10.1. Make no 

changes to the sampling system or EC cell calibration until all post-sampling calibration checks 

have been recorded. If either the zero or up-scale calibration error exceeds the respective 

specification in Sections 10.1.2 and 10.1.4 then all measurement data collected since the 

previous successful calibrations are invalid and re-calibration and re-sampling are required. If the 

sampling system is disassembled or the EC cell calibration is adjusted, repeat the calibration 

check before conducting the next analyzer sampling run.

11.0 Analytical Procedure 

The analytical procedure is fully discussed in Section 8.

12.0 Calculations and Data Analysis

Determine the CO and O2 concentrations for each stack gas sampling run by calculating the 

mean gas concentrations of the data recorded during the “measurement data phase”. 

13.0 Protocol Performance

Use the following protocols to verify consistent analyzer performance during each field sampling 

day.
115

13.1 Measurement Data Phase Performance Check. Calculate the mean of the readings from the 

“measurement data phase”. The maximum allowable deviation from the mean for each of the 

individual readings is ± 2 percent, or ± 1 ppm, whichever is less restrictive. Record the mean 

value and maximum deviation for each gas monitored. Data must conform to Section 10.1.4. The 

EC cell flow rate must conform to the specification in Section 8.3. 

Example: A measurement data phase is invalid if the maximum deviation of any single reading 

comprising that mean is greater than ± 2 percent or ± 1 ppm (the default criteria). For example, 

if the mean = 30 ppm, single readings of below 29 ppm and above 31 ppm are disallowed).

13.2 Interference Check. Before the initial use of the EC cell and interference gas scrubber in the 

field, and semi-annually thereafter, challenge the interference gas scrubber with NO and NO2 gas 

standards that are generally recognized as representative of diesel-fueled engine NO and NO2

emission values. Record the responses displayed by the CO EC cell and other pertinent data on 

Figure 1 or a similar form. 

13.2.1 Interference Response. The combined NO and NO2 interference response should be less 

than or equal to ± 5 percent of the up-scale CO calibration gas concentration. 

13.3 Repeatability Check. Conduct the following check once for each nominal range that is to be 

used on the CO EC cell within five days prior to each field sampling program. If a field sampling 

program lasts longer than five days, repeat this check every five days. Immediately repeat the 

check if the EC cell is replaced or if the EC cell is exposed to gas concentrations greater than 150 

percent of the highest up-scale gas concentration.

13.3.1 Repeatability Check Procedure. Perform a complete EC cell sampling run (all three 

phases) by introducing the CO calibration gas to the measurement system and record the 

response. Follow Section 10.1.3. Use Figure 1 to record all data. Repeat the run three times for a 

total of four complete runs. During the four repeatability check runs, do not adjust the system 

except where necessary to achieve the correct calibration gas flow rate at the analyzer.

13.3.2 Repeatability Check Calculations. Determine the highest and lowest average 

“measurement data phase” CO concentrations from the four repeatability check runs and record 

the results on Figure 1 or a similar form. The absolute value of the difference between the 
116

maximum and minimum average values recorded must not vary more than ± 3 percent or ± 1 

ppm of the up-scale gas value, whichever is less restrictive.

14.0 Pollution Prevention (Reserved)

15.0 Waste Management (Reserved)

16.0 Alternative Procedures (Reserved)

17.0 References

(1) “Development of an Electrochemical Cell Emission Analyzer Test Protocol”, Topical Report, 

Phil Juneau, Emission Monitoring, Inc., July 1997.

(2) “Determination of Nitrogen Oxides, Carbon Monoxide, and Oxygen Emissions from Natural 

Gas-Fired Engines, Boilers, and Process Heaters Using Portable Analyzers”, EMC Conditional 

Test Protocol 30 (CTM-30), Gas Research Institute Protocol GRI-96/0008, Revision 7, October 

13, 1997.

(3) "ICAC Test Protocol for Periodic Monitoring”, EMC Conditional Test Protocol 34 (CTM034), The Institute of Clean Air Companies, September 8, 1999.

(4) “Code of Federal Regulations”, Protection of Environment, 

40 CFR, Part 60, Appendix A, Methods 1-4; 10.

Table 1: Appendix A - Sampling Run Data.

Facility________________ Engine I.D.______________ Date_________

Run Type: (__) (__) (__) (__)

 (X) Pre-Sample Stack Gas Post-Sample Repeatability
117

 Calibration Sample Cal. Check Check

 

Run # 1 1 2 2 3 3 4 4 Time Scrub.

OK 

FlowRate

Gas O

2 

C

O

O

2

C

O

O

2

CO O2 CO

Sample 

Cond.

Phase

“

“

“

“

 

Measurement

Data Phase

“

“

“

“

“

“

“

“

“ 

“
118

 Mean

Refresh

Phase

“

“

“

“