p.1 

OAR Box 1811 

Prepped by Keeia Richards 

Document Number: 

77) IV-l-1 

Docket Number: 

A-84-22 

Printed 10/30/2008 1:19:25 PM Sheet 77 of 82 
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<*- 14246 Federal Register / Vol- 55. No. 74 / Tuesday. April 17, 1990 / Rules and Regulations IV-l- 1 

ENVIRONMENTAL PROTECTION 

AGENCY 

40CFRPartS1 

IAD-Ff.L-3700) 

Preparation, Adoption, and Submittal 

of State Implementation Plana; 

Methods for Measurement of PM,0 

Emissions from Stationary Sources 

AGENCY: Environmental Protection 

Agency (EPA). 

ACTION: Final rule. 

SUMMARY: The EPA has promulgated a 

revised National Ambient Air. Quality 

Standard (NAAQS) (53 FR 24634), 

which, depending on the control strategy 

adopted by the State, may require State 

implementation plans (SIPs) to contain 

emission limits for particulate matter 

(PM) with an aerodynamic diameter of 

nominally 10 f_m or less (PMio). Because 

of the need for a source test method for 

PMio, the Agency is adding two PMio 

methods. Methods 201 and 201A, for the 

measurement of in stack PMio emissions 

from stationary sources, to appendix M, 

40 CFR part 51. Appendix M is a newly 

designated repository for recommended 

test methods for SIP's. The Agency also 

is revising subpart K, 40 CFR part 51, to 

direct States to appendix M and to 

reiterate the fact that each SIP must 

include enforceable test methods with 

each emission limit in the SIP, including 

PMio. The PMio source test method shall 

be Method 201,201A, or an acceptable 

alternative. If the State intends to 

require the measurement of condensible 

emissions, then an enforceable method 

for the measurement of condensible 

emissions shall also be included in the 

SIP. Today's action promulgates 

Methods 201 and 201 A. The 

promulgation of these methods will give 

States more options in selecting the 

appropriate PMio source test methods in 

order to comply with NAAQS. 

DATES: Effective Date: April 17,1990. 

Judicial Review. Under section 

307(b)(1) of the Clean Air Act, judicial 

review of the actions taken by this 

notice is available only by the Tiling of a 

petition for review in the U.S. Court of 

Appeals for the District of Columbia 

Circuit on or before June 18,1990. Under 

section 307(b)(2) of the Clean Air Act, 

the requirements that are the subject of 

today's notice may not be challenged 

later in civil or criminal proceedings 

brought by EPA to enforce these 

requirements. 

ADDRESSES: Docket. Docket No. A-88-

08, containing materials relevant to this 

rulemaking, is available for public 

inspection and copying between 8:30 

a.m. and 3:30 p.m., Monday through 

Friday, at EPA's Air Docket (LE-131), 

Room M-1500,1st Floor, Waterside 

Mall, 401M Street SW., Washington. DC 

20460. A reasonable fee may be charged 

for copying. 

FOR FURTHER INFORMATION CONTACT: 

Roy Huntley or Roger Shigehara, 

Emission Measurement Branch (MD-19), 

Technical Support Division, telephone 

number (919) 541-1060, or Kenneth R. 

Woodard, Air Quality Management 

Division (MD-15), U.S. Environmental 

Protection Agency, Research Triangle 

Park, North Carolina 27711, telephone 

number (919) 541-5897. 

SUPPLEMENTARY INFORMATION: 

I. The Rulemaking 

Section 110 of the Clean Air Act, as 

amended (42 U.S.C. 7410), specifies that 

States are to submit plans for EPA 

approval that provide for the attainment 

and maintenance of emission standards 

through control programs directed at 

sources of the pollutants involved. 

Those plans shall include enforceable 

test methods for each emission limit, 

including in-stack PMio and condensible 

emissions, if applicable. The test method 

for in-stack PMio shall be Method 201, 

201A, or an acceptable alternative. 

Although EPA recognized this need on 

the part of the States for test methods 

when it proposed and promulgated the 

PMio standard and the associated 

implementation requirements, EPA did 

not have sufficient time and resources to 

develop a PMio source test method. 

Accordingly, EPA elected to provide 

States and local control agencies and 

the public with guidance on how a 

widely accepted source testing train, 

EPA's Method 5 train, could be modified 

to measure PMio. Appendix C of the 

PMio SIP Development Guideline gives 

instructions which would allow a person 

knowledgeable in source testing theory 

and methods to adapt a Method 5 train 

for measuring emissions of PMio. 

Improved PMio source test 

methodology has since been developed 

and, in order to make this methodology 

available to States, the EPA, in this 

notice, is promulgating two PMio source 

test methods in the Federal Register. 

The methods will be published as 

recommended test methods in appendix 

M, which this notice will designate as a 

repository for recommended test 

methods. Recommended test methods 

are methods that are not specifically 

required by Federal regulations, but are 

proposed and promulgated by the EPA 

for use by the States in their SIP's. 

Appendix- M, entitled Reco_nr3S_3_(_R frO 

Test Methods for State ImplemWatiBn Ji__ 

Plans, will contain methods numbered 

201-299. 

This notice also revises subpart K to 

emphasize the requirement that States 

must include enforceable test methods 

in their SIPs for each emission limit. 

Also, subpart K is revised to direct 

States to appendix M. Hie first method, 

Method 201 (also known as the Exhaust 

Gas Recycle (EGR) Procedure), uses a 

recycle loop to maintain a constant flow 

rate through a cyclone while 

maintaining isokinetic flow conditions 

at the nozzle. The second method, 

Method 201A [previously known as 

SIM-5 but now called the Constant 

Sampling Rate (CSR) Procedure in this 

action], maintains a constant sampling 

rate through the particle sizing device 

while keeping the anisokinetic errors 

within well defined limits. The EPA 

considers the methods equivalent in 

PMio measurement and is therefore 

promulgating both methods. 

In this notice, the EPA has dropped 

the requirement for an out-of-stack filter 

for Methods 201 and 201 A. The 

proposed methods with the out-of-stack 

filter were originally intended to 

measure in-stack PMio and condensible 

emissions at a reference temperature. 

As promulgated, the methods measure 

only in-stack PMio. However, the EPA 

recognizes that condensible emissions 

are also PMioi and that emissions that 

contribute to ambient PMio 

concentrations are the sum of in-stack 

PMio, as measured by Method 201 or 

201A, and condensible emissions. 

Therefore, for establishing source 

contributions to ambient concentrations 

of PMio for emission inventory purposes, 

EPA recommends that source PMio 

measurement include both in-stack PMio 

and condensible emissions. Condensible 

emissions may be measured by impinger 

analysis methods in combination,with 

either PMio method. The EPA intends to 

propose an impinger analysis method, 

named Method 202, in August, 1990. 

Draft copies of Method 202 are 

available. 

Secondary PM is formed in the 

atmosphere by chemical reactions 

among chemical pollutants and may also 

exist as ambient PMio but cannot be 

reliably measured. 

Technical Problems in PMl0 Emission 

Measurement 

The collection of PMio is based on the 

aerodynamic/inertial behavior of 

particles. PMio particulate matter is 

defined as all particles which are 

nominally 10 um aerodynamic size and 

o types of 

particle size 

mpactore and 

41 
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cyclones are most appropriate for the 

in-stack collection of PMre. Although 

similar principles are involved, when 

compared to«eca other, «adi hat 

advantages and disadvantages. -

Caecaue*_B_paLtuiB,aie oest suited for 

determining multiple cat fractious of VM. 

Their technology is developed te die 

paint that their penonnauce can 

generally be predicted very well from 

the geometry of die sizing device and 

flow considerations. However, because 

of potential sampling nozzle effects on 

die first stage, calibration is required for 

PMio sampling. Additionally, each stage 

can collect only a few milligrams of PM 

before particle bounce adversely affects 

collection performance. Omission of 

stages in impactors to reduce the 

number of size fractions and increase 

catch sizes hastens the increase of 

errors due to particle bounce. Because of 

these and other problems, die sampling 

times with cascade impactors are 

relatively short 

Cyclones perform well as single stage 

collectors, do not suffer from problems 

due to particle bounce, and have the 

potential of collecting PM mass in die 

order of grams. However, cunent 

theories on cyclone operations are not 

as well developed as diose for cascade 

impactors and cannot predict with as 

high degree of accuracy die performance 

of cyclones from geometrical and flow 

considerations. This limits die use of 

cyclones to those that have been 

demonstrated to produce die necessary 

particle cut size through empirical 

calibration procedures. The cut size, or 

DM, of an inertial sizing device is 

defined here as the aerodynamic 

diameter of a particle that has a 50 

percent probability of capture by the 

device. For both mediods, die 

measurement efficiencies for PMio 

particles rise extremely rapidly as 

particle size decreases below 10 pm 

aerodynamic size, and fall extremely 

rapidly as particle size increases above 

10 pm. These compensating 

measurement efficiencies result in the 

proper measurement of PMio emissions 

from stationary sources when the 

devices are operated at a Dbo, or cut 

size, of nominally 10 nm aerodynamic 

particle size. Consequently, cyclones 

capable of collecting PMio with 

acceptable sharpness of cut have been 

developed and are currently available 

for both the EGR and CSR sampling 

trains. 

Sampling from stacks presents 

challenges when using inertial sizing 

devices. For example, the aerodynamic 

cut size is a function of the flow rate and 

viscosity of the gas flowing through the 

sizing device. Therefore, the flow rate 

through die sizing device must be kept 

at a "constant discrete value remain tain 

the cut size at 10 pm. Since stack 

velocities usually vary from point to 

point maintaining both isokinetic 

sampling rates and constant sizing 

device flow rates in die sizing device is 

a problem not easily overcome. Hie two 

PMi* mediods offer different solutions to 

this problem. 

The EGR Procedure. The EGR train 

samples isokinetically at the nozzle tip 

and recycles a filtered, conditioned 

portion of the exhaust sampie gas 

dirough a single stage cyclone, thereby 

maintaining the constant flow rate 

dirough die cyclone required for a cut 

size of 10 pm. Isokinetic sampling is 

maintained by changing the recycle and 

sample flow rates such that die 

combined flow always equals the 

required constant flow rate. For 

example, if die stack gas velocity 

increases, the tester can increase the 

nozzle velocity to match the stack 

velocity by increasing the sample flow 

rate while simultaneously decreasing 

the recycle flow rate so that die total 

flow rate dirough die cyclone remains 

the same. Thus, the recycle capability of 

the EGR procedure permits the tester to 

sample isokinetically in the presence of 

variable stack gas velocity while 

maintaining a constant cut size of 10 pm 

in the cyclone. 

The EGR sampling train includes a 

meter and flow control console to 

monitor the sample, recycle, and total 

flow rates throughout die sampling train. 

The nozzle is constructed to allow for 

the addition of recycle exhaust gas. The 

sampling protocol is similar to Method 5 

except that the required maximum 

number of points in a stack is 12. 

The EGR procedure produces two 

fractions called catches. One is the PMio 

fraction (PMio catch) and the other is the 

remainder of the particulate matter in 

the sample, or die remaining fraction 

(cyclone catch). Therefore, die total PM 

catch can be calculated by summing the 

PMio catch and die cyclone catch. 

The EGR sampling train is available 

commercially, however, only one 

company is known presently to 

manufacture the train. The cost is 

approximately $19,000. Application 

guides and description of the inside 

dimensions of the cyclones and nozzles 

are available from EPA for use by the 

general public. These descriptions could 

be used as aids in the design of 

sampling trains for use in performance 

of the PMio source test methods. 

The CSR Procedure. The CSR sizing 

device can be either a cyclone or a 

cascade impactor. In this procedure, a 

constant sampling rate required for a 10 

pm cut size is maintained throughout tho 

sample traverse. The anisokinetic error 

is kept within acceptable limits by 

specifying a permissible range of 

velocity values for each sampling probe 

nozzle. The nozzle selected is die one 

whose maximum and minimum velocity 

values bracket all of the actual sampling 

point velocities. Often only one nozzle is 

required to complete a sampling run, but 

should the sampling point velocities 

vary beyond the specified range of any 

single nozzle, the use of more than one 

nozzle and sampling train per traverse 

would be necessary. 

To add practicality to the procedure, 

the criteria for accepting die results in 

terms of isokinetic variation are more 

liberal than for the EGR procedure. Ihe 

actual isokinetic variation allowed in 

the CSR method varies with stack gas 

velocity, but ranges from ±20 to ±40 

percent Because larger particles are 

more affected by anisokinetic sampling 

error than PMio, the total PM catch may 

not be as accurate as the EGR 

procedure. To account for the effects of 

sampling anisokineticaily, the sampling 

time at each point is adjusted 

proportionally to the velocity at that 

point to provide a velocity weighted 

sample. 

The CSR procedure uses a standard 

Method 5 sampling train, an in-stack 

glass fiber filter, and an inertial sizing 

device, either a cyclone or a cascade 

impactor. The cascade impactors will 

have to be calibrated for this procedure. 

The approximate cost of a calibrated 

impactor, pre-collector, and 11 nozzles is 

$&000. The approximate cost of a PM,0 

cyclone and 11 nozzles is $3,000. 

IL Public Participation 

The opportunity to hold a public 

hearing on July 21,1989 at 10 a.m. was 

presented in the proposal notice, but no 

one desired to make an oral 

presentation. The public comment 

period was from June 6,1989 to August 

25,1989. Eleven letters were received. 

OL Significant Comments and Changes 

to the Test Methods 

Interested parties were advised by a 

Notice of Proposed Rulemaking (54 FR 

24213) of the Agency's intention to 

promulgate methods to measure PMio 

source emissions. The comment period 

extended from June 6.1989 to August 21. 

1989. Eleven comment letters were 

received. 

Commenters included five trade 

associations, three local air pollution 

control agencies, two chemical 

companies, and one environmental 

consulting firm. The major comments 

and responses are summarized below. 

k 
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14248 Federal Register / Vol. 55. No. 74 / Tuesday. April 17. 1990 / Rules and Regulations 

Four commenters objected to the use 

of the out-of-stack filter because die 

weight of the heavy sampling apparatus 

(cyclone, nozzle, pitot and filter holder) 

would break a conventional Method 5-

type glass liner. Another commenter 

objected to the 248 °F temperature 

requirement of the out-of-stack filter and 

recommended that the out-of-stack filter 

temperature be 320 °F for subpart D, Da, 

Db, and J sources, as presently allowed 

for total mass determination. Another 

commenter suggested that the total 

pressure drop across the system with 

two filters was so large that the pump 

may not be able to maintain an 

isokinetic sampling rate. 

As stated earlier, the EPA has 

dropped the requirement for an out-ofstack filter for Methods 201 and 201A 

because the development of a 

condensible PM method is near 

completion. As promulgated, the 

methods measure only in-stack PMio. 

However, the EPA recognizes that 

condensible emissions are also PMio. 

and that emissions that contribute to 

ambient PMio concentrations are the 

sum of in-stack PMio, as measured by 

Method 201 or 201A, and condensible 

emissions. Therefore, for establishing 

source contributions to ambient 

concentrations of PMio for emission 

inventory purposes, EPA recommends 

that source PM,0 measurement include 

both in-stack PM,_ and condensible 

emissions. Condensible emissions may 

be measured by impinger analysis 

methods in combination with either 

PMio method. 

Two commenters are concerned about 

how well the methods compare to each 

other. Several commenters are 

concerned about operator error and the 

accuracy and precision of the two 

methods and suggest collaborative 

testing. 

Methods 201 and 201A were 

compared directly to each other by 

coincidental source sampling in which 

the two sampling trains were operated 

side by side in the same stack. 

Comparability is within 16 percent and 

normal distribution was shown as the 

methods alternated in sign compared to 

each other. Precision of Methods 201 

and 201A was established by operating 

at least two EGR trains coincidentally 

and two CSR trains similarly. The 

precision of the methods were equal to 

or better than those reported for 

Methods 5 and 17. 

One commenter thinks that EPA 

should define "example test methods" 

that are to be in part 51, appendix M, 

and two commenters are concerned 

about what the EPA considers an 

acceptable alternative. 

"Example test mediods" in appendix 

M are test methods that have completed 

die normal promulgation procedures for 

EPA test methods and are recommended 

for use by states in their SIPs. Based on 

this comment, the EPA has changed the 

designation of the test methods in 

appendix M from "example" test 

methods to "recommended" test 

methods. 

The acceptability of an alternative 

method to any EPA method is a 

determination made by the 

Administrator. Guidelines for 

determining the acceptability of 

alternative methods are available and 

can be obtained from Roy Huntley, 

Emission Measurement Branch (MD-19), 

Technical Support Division, U.S. 

Environmental Protection Agency, 

Research Triangle Park, North Carolina 

27711, telephone number (919) 541-1060. 

Another commenter said that using 

Method 5 and an assumed PMio ratio 

would be cheaper than a direct 

measurement of PMio and should be 

allowed by the EPA. 

The EPA does not anticipate that the 

cost of a PMio emission test will be 

substantially higher than a Method 5 

emission test 

One commenter notes the 6 inch 

sampling port requirement of both PMio 

methods and recommends that EPA 

limit the use of Method 201 to stacks 

having diameters of 12 inches or greater. 

As an alternative, EPA should allow the 

use of California Air Resources Board 

(CARB) Method 501. which is reportedly 

effective for use on stacks with 

diameters as small as 4 inches. 

According to EPA Method 2, velocity 

measurement error due to blockage 

becomes significant when the crosssectional area of the sampling apparatus 

is 3 percent or greater of the stack crosssectional area. This guidance is the 

same for CARB Method 501 and EPA 

Methods 201 and 201A. Using this 

criteria and the currendy available EGR 

and CSR sampling apparatus, the 

minimum stack diameter that can be 

tested without significant error due to 

blockage is approximately 30 inches. 

Smaller diameter stacks can be sampled 

by using Method 2C to measure point 

velocity. 

Several commenters were concerned 

that the mediods cannot accurately 

measure PMio in stacks with entrained 

moisture droplets. 

The PMio mediods are not 

recommended for stacks with entrained 

moisture droplets because water drops 

larger than PMio. which are captured by 

the PMio cyclone, may contain particles 

which normally would be counted as 

PMio. Thus, PMio measurements in 

stacks with entrained moisture may 

have a low bias with respect to PMio 

emissions. 

One commenter preferred to 

determine PMio emissions by measuring 

the PMio fraction by an impactor and the 

total mass emissions by Method 5, 

obtaining the PM.0 mass emissions by 

multiplying the fraction of PMio by the 

total emissions. 

The EPA does not consider this 

method acceptable. The impactor 

method determines the in-stack PMio 

fraction and Method 5 determines the 

total particulate matter at a reference 

temperature, usually 248 "F. The in-stack 

impactor measures PMio that exists in 

the stack and does not measure the 

extra PMio that condenses and is 

collected in the probe and on the out-ofstack filter. Multiplying an in-stack PMio 

fraction by a total mass determined by 

Method 5 would typically give a low 

bias for PMio emissions, unless the stack 

temperature was 248 °F or less. 

One commenter suggested that the 

sizing device be removed prior to the 

post test leak-check because the release 

of the vacuum will disturb the sample. 

Both mediods have been changed to 

allow the tester the option of removing 

the sizing device prior to the post test 

leak-check. However, if this option is 

chosen, then a leak-check of the entire 

train, including the sizing device, is 

required immediately prior to each run. 

One commenter notes that existing 

cascade impactors do not meet EPA 

specifications and concludes that 

cascade impactors should not be 

allowed as an option in Method 201A 

until extensive recalibration has been 

performed. 

The EPA agrees with the commenter 

and has included the calibration 

procedure for cascade impactors in 

Method 201A. 

Another possible source of error cited 

by one commenter is that the PMio 

mediods collect and measure only 50 

percent of the particles 10 pm in 

diameter. 

For both methods, the measurement 

efficiencies for PMio particles rise 

extremely rapidly as particle size 

decreases below 10 pm aeordynamic 

size, and fall extremely rapidly as 

particle size increases above 10 pm. 

These compensating measurement 

efficiencies result in die proper 

measurement for PMio emissions from 

stationary sources when the devices are 

operated to produce a cut point (DM) of 

nominally 10 pm aerodynamic particle 

size. 

Concern was expressed about the fact 

that use of dry recycle gas can cause 

wet particles to shrink, thus causing 
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Federal Register / Vol. 55. No. 74 / Tuesday. April 17, 1990 / Rules and Regulations 14249 

them to be erroneously measured as 

PM,». 

Drying and shrinking is not thought to 

be a problem. Should it be considered a 

problem, the tester could choose Method 

201A in which there is no recycle gas. 

Another commenter said that the use 

of recycle gas increases velocity in the 

cyclone which could cause friable 

particles to break up, becoming PMt0. 

Prior to size classification by a PMio 

cyclone, there is no known or suspected 

mechanism by which friable particles, 

should they exist, may break up. When 

particles greater than 10 pm 

aerodynamic size reach the cyclone wall 

due to their inertia, they are collected. 

One commenter said that no 

consideration is made in either method 

of the gas density, gas viscosity, or of 

the density of the particulate matter 

being measured. 

Cas density and viscosity are 

compensated for in the calculations for 

both PMio methods. Because the 

aerodynamic diameter of PMio 

emissions is used in both PMio methods, 

determination of particle densities, 

volumes, or shapes is not necessary and 

would be redundant. 

Another commenter said if the PMio 

measurement is made downstream of an 

electrostatic precipitater (ESP), tiien the 

particles will carry an electric charge 

and the measurement of PMio by these 

methods will be affected. 

The effect of an ESP on particle sizing 

when using Method 201 or 201A is 

considered to be negligible. 

There was concern by the commenters 

that the particulate matter may settle 

out inside the sample train. 

The trains have been calibrated with 

test aerosols and the relative accuracies 

to each other have been established. 

These tests results and die operation 

principles of both methods have shown 

that "settling" is not a problem. The 

particles travel only 1.5 to 3 in. (nozzle 

length] prior to size classification by the 

trains. 

IV. Administrative 

The docket is an organized and 

complete file of all the information 

considered by EPA in the development 

of this rulemaking. The docket is a 

dynamic file since material is added 

throughout the rulemaking development. 

The docketing system is intended to 

allow members of the public and 

industries involved to identify readily 

and locate documents so that they can 

effectively participate in the rulemaking 

process. Along with the statement of 

basis and purpose of the proposed and 

promulgated test method revisions and 

EPA responses to significant comments, 

the contents of the docket, except for 

interagency review materials, will serve 

as the record in case of judicial review 

(section 307(d)(7)(A)). 

Under Executive Order 12291, EPA is 

required to judge whether a regulation is 

a "major rule" and, therefore, subject to 

the requirements of a regulatory impact 

analysis. The Agency has determined 

that this regulation would result in none 

of the adverse economic effects set forth 

in section 1 of the Order as grounds for 

finding a regulation to be a "major rule." 

The Agency has, therefore, concluded 

that this regulation is not a "major rule" 

under Executive Order 12291. 

The Regulatory Flexibility Act (RFA) 

of 1980 requires the identification of 

potentially adverse impacts of Federal 

regulations upon small business entities. 

The Act specifically requires the 

completion of a RFA analysis in those 

instances where small business impacts 

are possible. Because this rulemaking 

imposes no adverse economic impacts, 

an analysis has not been conducted. 

List of Subjects in 40 CFR Part 51 

Administrative practice and 

procedure, Air pollution control, Carbon 

monoxide. Intergovernmental relations, 

Lead. Nitrogen dioxide, Ozone, 

Particulate matter, Reporting and 

recordkeeping requirements, Sulfur 

oxides, Volatile organic compounds. 

Dated: March 22.1990. 

William K. Reilly, 

Administrator. 

The EPA amends title 40, chapter I, 

part 51 of the Code of Federal 

Regulations as follows: 

PART 51—[AMENDED] 

1. The authority citation for part 51 is 

revised to read as follows: 

Authority: 42 U.S.C. 7401(b)(1), 7410, 7470-

7479. 7501-7508. and 7601(a). unless 

otherwise noted. 

2. Subpart K. $ 51.212 is amended by 

adding paragraph (c) to read as follows: 

$ 51-212 Testing, Inspection, enforcement 

and complaints. 

* • * * * 

(c) Enforceable test methods for each 

emission limit specified in the plan. As 

an enforceable method. States may use: 

(1) Any of the appropriate methods in 

appendix M to this part, Recommended 

Test Methods for State Implementation 

Plans; or 

(2) An alternative method following 

review and approval of that method by 

the Administrator or 

(3) Any appropriate method in 

appendix A to 40 CFR part 60. 

3. Appendix M is added to part 51 to 

read as follows: 

Appendix M—Recommended Test 

Mediods for State Implementation Plans 

Method 20*1—Determination of PMio 

Emissions (Exhaust Gas Recycle Procedure). 

Method 201A—Determination of PMio 

Emissions (Constant Sampling Rate 

Procedure). 

Presented herein are recommended test 

methods for measuring air pollutants 

emanating from an emission source. They are 

provided for States to use in their plans to 

meet the requirements of Subpart K—Source 

Surveillance. 

The State may also choose to adopt other 

methods to meet the requirements of Subpart 

K of this part, subject to the normal plan 

review process. 

The State may also meet the requirements 

of Subpart K of this part by adopting, again 

subject to the normal plan review process, 

any of the relevant methods in appendix A to 

40 CFR part 60. 

Method 201—Determination of PMio 

Emissions 

(Exhaust Cas Recycle Procedure) 

1. Applicability and Principle 

1.1 Applicability. This method applies to 

the in-stack measurement of particulate 

matter (PM) emissions equal to or less than 

an aerodynamic diameter of nominally 10 jim 

(PMio) from stationary sources. The EPA 

recognizes that condensible emissions not 

collected by an in-stack method are also 

PMio. and that emissions that contribute to 

ambient PMio levels are the sum of 

condensible emissions and emissions 

measured by an in-stack PMio method, such 

as this method or Method 201A. Therefore, 

for establishing source contributions to 

ambient levels of PMio. such as for emission 

inventory purposes, EPA suggests that source 

PMio measurement include both in-stack PMio 

and condensible emissions. Condensible 

missions may be measured by an impinger 

analysis in combination with this method. 

1.2 Principle. A gas sample is 

isokinetically extracted from the source. An 

in-stack cyclone is used to separate PM 

greater than PMio. and an in-stack glass fiber 

filter is used to collect the PMio. To maintain 

isokinetic flow rate conditions at the tip of 

the probe and a constant flow rate through 

the cyclone, a clean, dried portion of the 

sample gas at stack temperature is recycled 

into the nozzle. The particulate mass is 

determined gravimetrically after removal of 

uncombined water. 

2. Apparatus 

Note: Method S as cited in this method 

refers to the method in 40 CFR part 60. 

appendix A. 

2.1 Sampling Train. A schematic of the 

exhaust of the exhaust gas recycle (EGR) 

train is shown in Figure 1 of this method. 

2.1.1 Nozzle with Recycle Attachment. 

Stainless steel (316 or equivalent) with a 

sharp tapered leading edge, and recycle 

attachment welded directly on the side of the 

nozzle (see schematic in Figure 2 of this 

method). The angle of the taper shall be on 

the outside. Use only straight sampling 

nozzles. "Gooseneck" or other nozzle