United States Office of Air Quality EPA-454/R-00-039

Environmental Protection Planning and Standards September 2000

Agency Research Triangle Park, NC 27711

Air

CURRENT KNOWLEDGE OF PARTICULATE

MATTER (PM) CONTINUOUS EMISSION

MONITORING
Current Knowledge of Particulate Matter (PM) 

Continuous Emission Monitoring

FINAL REPORT

For U.S. Environmental Protection Agency

Office of Air Quality Planning and Standards

Emission, Monitoring and Analysis Division

Emission Measurement Center

Research Triangle Park, North Carolina 27711

Attn: Mr. Dan Bivins

EPA Contract No. 68-W6-0048

Work Assignment No. 3-07 and 4-03

MRI Project Nos. 104702-1-007-07-15

104703-1-003-07

September 8, 2000
ii

PREFACE

This document was prepared by Midwest Research Institute (MRI) for the U. S.

Environmental Protection Agency (EPA) under Contract No. 68-W6-0048, Work

Assignments 3-07 and 4-03. Mr. Dan Bivins was the EPA Work Assignment Manager (WAM). 

This document summarizes the EPA’s current knowledge of particulate matter continuous

emission monitoring. The document consists of one volume with 98 pages and one appendix.

MIDWEST RESEARCH INSTITUTE

Craig Clapsaddle

Task Leader

Andrew Trenholm

Work Assignment Leader

Approved:

Joe Palausky

Program Manager

September 8, 2000
iii

TABLE OF CONTENTS

Page

PREFACE ................................................................. ii

EXECUTIVE SUMMARY ................................................... vi

1.0 INTRODUCTION ..................................................... 1-1

2.0 HISTORICAL PERSPECTIVE OF CONTINUOUS PM MONITORING ........... 2-1

2.1 OVERVIEW OF REGULATORY USE ............................... 2-1

2.2 PAST STUDIES ................................................. 2-2

2.3 CURRENT EUROPEAN EXPERIENCE .............................. 2-8

3.0 ANALYTICAL PRINCIPLES ............................................ 3-1

3.1 LIGHT SCATTERING ............................................ 3-1

3.2 BETA ATTENUATION .......................................... 3-2

3.3 PROBE ELECTRIFICATION (TRIBOELECTRIC EFFECT) .............. 3-3

3.4 LIGHT EXTINCTION (TRANSMISSOMETER) ....................... 3-3

3.5 OPTICAL SCINTILLATION ....................................... 3-5

4.0 SUMMARY OF KNOWN PM CEMS ...................................... 4-1

4.1 DURAG F904K BETA ATTENUATION .............................. 4-2

4.2 ENVIRONMENT S.A. 5M BETA ATTENUATION ..................... 4-3

4.3 MECHANICAL SYSTEMS INC. BETAGUARD PM BETA

ATTENUATION .............................................. 4-4

4.4 SIGRIST KTNR AND CTNR EXTRACTIVE LIGHT SCATTER ........... 4-5

4.5 DURAG DR-300-40 IN-SITU LIGHT SCATTER ....................... 4-6

4.6 ENVIRONMENTAL SYSTEMS CORPORATION P5 IN-SITU

LIGHT SCATTER ............................................. 4-6

4.7 SICK INC. RM210 IN-SITU LIGHT SCATTER ........................ 4-7

4.8 SICK INC. FW 100 IN-SITU AND FWE 200 EXTRACTIVE LIGHT

SCATTER ................................................... 4-8

4.9 GRIMM TECHNOLOGIES 6300 IN-SITU LIGHT SCATTER ............. 4-8

4.10 MONITOR LABS 300L IN-SITU LIGHT SCATTER ................... 4-9

4.11 BHA GROUP CPM 5000 SCINTILLATION .......................... 4-9

4.12 PCME SCINTILLA SC600 SCINTILLATION ........................ 4-10

4.13 INSITEC TESS IN-SITU OR EXTRACTIVE LASER LIGHT

EXTINCTION-SCATTER ...................................... 4-11

4.14 PCME DUSTALERT 90 ELECTROSTATIC INDUCTION ............. 4-11

4.15 AUBURN INTERNATIONAL TRIBOGUARD III OR II IN-SITU

TRIBOELECTRIC ............................................ 4-12

4.16 CODEL STAKGARD TRIBOELECTRIC DUST MONITOR ............ 4-12

4.17 OPACITY/TRANSMISSOMETERS ............................... 4-13
TABLE OF CONTENTS (CONTINUED)

Page

iv

5.0 SUMMARY OF PM CEMS DEMONSTRATION FIELD STUDIES .............. 5-1

5.1 TÜV CERTIFICATION TESTING OF PM CEMS ...................... 5-1

5.1.1 Sigrist CTNR ............................................ 5-1

5.1.2 Durag F-904 ............................................. 5-2

5.1.3 Durag DR-300-40 ......................................... 5-3

5.2 EPA/OSW FIELD DEMONSTRATION – HAZARDOUS WASTE

INCINERATORS ............................................. 5-4

5.2.1 Mixed Solid and Liquid Hazardous Waste Incinerator .............. 5-4

5.2.2 Hazardous Waste Burning Cement Kiln ........................ 5-5

5.2.3 DuPont Hazardous Waste Incinerator .......................... 5-6

5.3 ELECTRIC POWER RESEARCH INSTITUTE – COAL-FIRED BOILER

WITH ESP ................................................... 5-8

5.4 ELI LILLY – HAZARDOUS WASTE INCINERATOR .................. 5-10

5.4.1 Phase One .............................................. 5-11

5.4.2 Phase Two ............................................. 5-11

5.5 EPA/OAQPS FIELD DEMONSTRATION – COAL-FIRED BOILER

WITH BAGHOUSE ........................................... 5-13

6.0 FUTURE FIELD DEMONSTRATIONS .................................... 6-1

6.1 TEST PLAN GUIDELINES ........................................ 6-1

6.2 MONITOR SELECTION GUIDELINES .............................. 6-2

6.3 TEST PLAN APPROVAL AND DATA ANALYSIS ..................... 6-3

7.0 PM CEMS IMPLEMENTATION ......................................... 7-1

7.1 SOURCE APPLICABILITY ........................................ 7-1

7.2 PM CEMS SELECTION .......................................... 7-2

7.3 SITE-SPECIFIC CORRELATION TEST .............................. 7-4

7.4 UNDERSTANDING THE MEANING OF THE CORRELATION .......... 7-7

7.5 QUALITY ASSURANCE/QUALITY CONTROL ....................... 7-8

7.6 PS-11 ISSUES TO BE ADDRESSED CASE BY CASE ................. 7-11

8.0 SUMMARY OF PS-11 AND PROCEDURE 2 ................................ 8-1

8.1 PS-11 ......................................................... 8-1

8.2 PROCEDURE 2 ................................................. 8-3

9.0 PM CEMS COST ...................................................... 9-1

10.0 REFERENCES ...................................................... 10-1

APPENDIX A. BREAKDOWN OF PM CEMS COSTS ........................... A-1
TABLE OF CONTENTS (CONTINUED)

Page

v

LIST OF TABLES

TABLE 2-1. NSPS REQUIRING COMS ....................................... 2-1

TABLE 2-2. PM MONITOR EVALUATION RESULTS AT A SECONDARY LEAD

SMELTER ................................................... 2-6

TABLE 2-3. GERMAN SUITABILITY TEST SPECIFICATIONS FOR APPROVAL .... 2-9

TABLE 2-4. MCERTS PM CEM EVALUATION CHARACTERISTICS ............. 2-13

TABLE 4-1. COMPARISON OF OPACITY MONITORS AS PM CEMSs ............ 4-14

TABLE 5-1. PM CONCENTRATIONS FOR THE THREE WEEKS OF THE EPRI

PM CEMS TEST ............................................... 5-9

TABLE 5-2. PM CEMSs CORRELATION STATISTICS FOR THE EPRI

PM CEMS TEST .............................................. 5-10

TABLE 5-3. PM CEMSs CORRELATION STATISTICS FOR THE LILLY

PHASE TWO PM CEMSs TEST ................................. 5-13

TABLE 5-4. PM CONCENTRATIONS FOR THE EPA/OAQPS PM CEMS TEST ..... 5-15

TABLE 5-5. PM CEMSs CORRELATION STATISTICS FOR THE OAQPS

PM CEMSs FIELD EVALUATION ............................... 5-16

TABLE 9-1. IN-SITU (LIGHT SCATTERING) PM CEMS COSTS .................. 9-1

TABLE 9-2. EXTRACTIVE (BETA GAUGE) PM CEMS COSTS ................... 9-1
vi

EXECUTIVE SUMMARY

Continuous monitoring of particulate matter (PM) concentrations in smoke stacks started

during the 1960s in Germany and became a German Federal requirement in the mid 1970s. In the

United States, PM concentrations were correlated to opacity monitor readings during the 1970s. 

Then, in the mid 1970s, the EPA dictated the use of transmissometers for continuous monitoring

of the opacity of emissions from sources. Opacity is used as a surrogate for PM emissions and

provides qualitative information on the operation and maintenance of particulate control

equipment. Continuous particulate mass monitoring was proposed as an EPA regulatory

requirement on April 19, 1996, as part of the proposed Hazardous Waste Combustion MACT

standard (61 FR 17358). The EPA also proposed performance specification (PS)-11,

Specifications and Test Procedures for Particulate Matter Continuous Emission Monitoring

Systems in Stationary Sources, to evaluate the acceptability of a PM continuous emission

monitoring system (CEMS). The Portland Cement Manufacturing MACT Final Rule

(64 FR 31898, June 14, 1999) in section 63.1250(k) makes mandatory the use of PM CEMSs

although not until the EPA has finalized PS-11.

Five analytical principles (light scattering, beta attenuation, probe electrification, light

extinction, and optical scintillation) used in instruments to measure PM concentrations are

described in this document. The following monitors are described in detail and are commercially

available from manufacturers as “off-the-shelf” PM continuous emission monitors:

Durag F904K Beta Attenuation

Environment S.A. 5M Beta Attenuation

Mechanical Systems Inc. BetaGuard PM Beta Attenuation

Sigrist KTNR and CTNR Extractive Light Scatter

Durag DR-300-40 In-situ Light Scatter

Environmental Systems Corporation P5 In-situ Light Scatter

Sick Inc. RM210 In-situ Light Scatter

Sick Inc. FW 100 and FWE 200 Light Scatter

Grimm Technologies Inc. Model 6300 In-situ Light Scatter

Monitor Labs Model 300L In-situ Light Scatter

BHA Group CPM 5000 Scintillation
vii

PCME Scintilla SC600 Scintillation

Insitec TESS In-situ or Extractive Laser Light Extinction-Scatter

PCME DustAlert 90 Electrostatic Induction

Auburn International Triboguard III or II In-situ Triboelectric

Codel StakGard Triboelectric Dust Monitor

Several opacity monitors are included for completeness.

PS-11 is used for evaluating the acceptability of an installed PM CEMS. This

performance specification requires site-specific correlation of the PM CEMS response against

manual gravimetric EPA Methods. PS-11 outlines the procedures and acceptance criteria for

installation and operation of instrumentation and for calculations and reporting of data generated

during a PM CEMS correlation. PS-11 is unique, relative to the performance specifications for

other CEMS, because it is based on a technique of correlating a PM CEMS’s response to

emissions determined by the manual PM method. In conjunction with PS-11, Procedure 2, which

was also proposed in 1996 with PS-11, stipulates the quality assurance (QA) and quality control

(QC) measures that must be applied to a PM CEMS.

In Germany to meet regulatory monitoring requirements for a particular industry type, a

specific model PM CEMS must pass a suitability test and be approved by the German Federal

Environmental Agency before it can be installed and used as a PM CEMS. The suitability test

consists of both a laboratory evaluation and a field evaluation. The United Kingdom has a similar

approval mechanism for a PM CEMS.

The EPA and industry have done the following recent field evaluations of PM CEMS:

• EPA/Office of Solid Waste (OSW) – 3 PM CEMSs at a mixed solid and liquid hazardous

waste incinerator located in Bridgeport, New Jersey during March 1995.

• EPA/OSW – 2 PM CEMSs at a hazardous waste cement kiln located in Fredonia, Kansas

during May through July 1995.

• EPA/OSW – 5 PM CEMSs at the DuPont Experimental Station’s hazardous waste

incinerator located in Wilmington, Delaware during September 1996 through May 1997.

• Electric Power Research Institute – 4 PM CEMSs at Georgia Power Company’s Plant

Yates coal-fired boiler located in Newnan, Georgia during June through September 1998.
viii

• Eli Lilly, the Chemical Manufacturers Association, and the Coalition for Responsible

Waste Incineration – 2 PM CEMSs at a liquid hazardous waste incinerator at the Eli Lilly

Clinton Lab in Clinton, Indiana during February through June 1998 and November

through December 1998.

• EPA/OAQPS – 3 PM CEMSs at a coal-fired boiler located in Battleboro, North Carolina

during June 1999 through February 2000.

Results of the EPA and industry field evaluations are described in this document.
1-1

1.0 INTRODUCTION

This report provides detailed information on the current knowledge of PM CEMSs. This

information was gained from literature reviews; attendance at many meetings and conferences

where the use of PM CEMSs was discussed; shared knowledge between the EPA, industry, and

consultants experienced with PM CEMSs in both the United States and Europe; discussions with

PM CEMS vendors; and personal experiences from performing a field demonstration of PM

CEMSs. The report will be maintained as a “living document” with periodic updates as needed.

The report is primarily written to provide information useful to State permitting authorities

and EPA Regional personnel. However, the information contained herein will be useful to all

persons involved with a PM CEMS program. It includes (1) technical information on the

monitors and their principal of operation, (2) their use history, (3) a summary of recent PM

CEMS field demonstrations, (4) recommendations for future field demonstrations,

(5) recommendations on how to implement a PM CEMS program, (6) a summary of the

performance specification for PM CEMSs, and (7) cost information.

A draft of this report was sent to 14 individuals with different view points and knowledge

in the field of continuous PM monitoring. The EPA received comments from nine reviewers, and

their comments were incorporated into this final report.
2-1

2.0 HISTORICAL PERSPECTIVE OF CONTINUOUS PM MONITORING

2.1 OVERVIEW OF REGULATORY USE

Continuous monitoring of PM concentrations in smoke stacks started during the 1960s in

Germany. In the United States during the 1970s, PM concentrations were correlated to opacity

monitor readings, but the EPA dictated the use of transmissometers to continuously monitor the

opacity of emissions from sources. For the EPA’s emission monitoring regulations and State

Implementation Plans (SIP), opacity is used as a surrogate for PM emissions and provides

qualitative information on the operation and maintenance of particulate control equipment. The

EPA’s New Source Performance Standards (NSPS) require continuous monitoring of opacity of

emissions from the 11 source categories presented in Table 2-1. 

TABLE 2-1. NSPS REQUIRING COMS

Source category 40 CFR Part 60 Subpart

Electric Power Plants D, Da, Db, Dc

Portland Cement Plants (Kiln and Clinker cooler) F

Petroleum Refineries (FCCU) J

Primary Copper Smelters (Dryer) P

Primary Zinc Smelters (Sintering machine) Q

Primary Lead Smelters (Blast furnace, Dross

reverberatory furnace, and Sintering machine)

R

Ferroalloy Production (Control device) Z

Electric Arc Furnace in steel mills (Control device) AA

Kraft Pulp Mills (Recovery furnace) BB

Lime Kilns (Rotary lime kiln) HH

Phosphate Rock Plants (Dryer, Calciner, Grinder) NN

In Germany, the first laws to require continuous monitoring of PM emissions came on

December 29, 1959 in the German Federal Law for Citizens (Act to Amend the Industrial Code...,

1959). Then in 1964, a more concrete requirement for continuous PM monitoring that included

many types of industrial plants was amended in the Technical Instruction for Air Pollution Control
2-2

(TA Luft, 1964). Plants with emissions exceeding 55 pounds per hour were required to

continuously monitor PM concentration in mg/acm “as soon as a suitable instrument becomes

available.” The requirements in TA Luft of 1964 initiated field studies of continuous PM emission

monitoring instrumentation. Several field-based research projects were completed by the German

federal government in the years following the German Federal Law of Environmental Protection

(BlmSchG, March 15, 1974). These field studies were completed to correct deficiencies found in

the measurement technology and formed the basis for the German’s instrument approval process

(see Section 2.3). Additional legislative rules detailed the monitoring requirements for power

plants (13th BlmSchV, 1983) and waste incinerators (17th BlmSchV, 1990) (Breton, 1989,

Martin, 1994, Jockel, 1998, and Jockel, 1999).

In the United States in 1975, the EPA promulgated Performance Specification - 1 (PS-1),

Specifications and Test Procedures for Opacity Continuous Emission Monitoring Systems in

Stationary Sources, to govern the design, performance, and installation of COMS (40 FR 64250,

October 6, 1975). In 1983, the EPA amended PS-1 (48 FR 13322, March 30, 1983), and in

2000, the EPA amended PS-1 again by incorporating ASTM D6216-98 design and monitor

manufacturer performance specifications (65 FR 48914, August 10, 2000).

Continuous particulate mass monitoring was proposed as an EPA regulatory requirement

April 19, 1996, as part of the proposed Hazardous Waste Combustion MACT emission standard

(61 FR 17358). As part of the Hazardous Waste Combustion MACT, the EPA proposed PS-11,

Specifications and Test Procedures for Particulate Matter Continuous Emission Monitoring

Systems in Stationary Sources, to evaluate the acceptability of a PM CEMS. The Portland

Cement Manufacturing MACT Final Rule in section 63.1250(k) (64 FR 31898, June 14, 1999)

makes mandatory the use of PM CEMSs although not until the EPA has finalized PS-11.

2.2 PAST STUDIES

During the 1970s, the EPA sponsored several studies to examine the applicability of

transmissometers to sources and the potential to correlate opacity to PM mass concentrations. 

Some of those studies are summarized below. Into the 1980s, philosophies changed within the

EPA, and continuous PM monitoring was not a priority. Work on the PM CEMS in this country

stopped until new initiatives started in the mid 1990s.
2-3

In a 1974 publication from the EPA’s National Environmental Research Center, Conner

(1974) showed that smoke’s opacity is related to (1) the size of the particles and (2) the light

wavelength used by a transmissometer. Particles much smaller than the light wavelength (particle

diameter < 0.05 μm in white light) contribute little to the opacity (extinction coefficient < 0.01). 

For particles much larger than the light wavelength (particle diameter > 2 μm in white light), the

opacity is not a function of the light wavelength, and the mean extinction coefficient is about 2. 

For particles about the same size as the light wavelength (0.05 < d < 2 μm in white light), opacity

has a strong dependence on the particle diameter, that is, the extinction coefficient increases from

0.01 to as high as 3 or 4 as the particle diameter increases from 0.05 μm to 2 μm. Also, Conner

detailed the effect of a transmissometer’s light wavelength on the opacity of fine particles (Conner

et al., 1967). Opacity determined from a blue light source has a positive bias (e.g., in a white

plume, an opacity of 25 percent, as determined by white light, is seen as about 40 percent by blue

light), and opacity determined from a red light source has a negative bias (e.g., in a white plume,

an opacity of 25 percent, as determined by white light, is seen as about 18 percent by red light). 

Opacity determined from an infrared light source has a strong negative bias (e.g., in a white

plume, an opacity of 25 percent, as determined by white light, is seen as about 5 percent by

infrared light). A black plume demonstrates the same biases but to a lesser degree.

As of 1974, the EPA had not resolved a transmissometer’s ability to monitor PM mass

concentrations from sources. Some investigators reported good empirical correlations between

mass concentration and light transmittance while others indicated that the effect of particle

characteristics on the correlation was too strong for a meaningful correlation. At that time, the

researchers clearly understood that for a useful correlation to exist between opacity and PM mass

concentration, the particle characteristics (size, shape, and composition) needed to be sufficiently

consistent and to remain consistent over time (Conner, 1974). Conner (1974) showed mass

concentration versus opacity for a kraft pulp mill recovery furnace, a cement plant kiln, and a

coal-fired boiler. The concentration versus opacity graphs showed that a strong linear

relationship existed between mass concentration and opacity at those three sources. Conner

noted that particulate emission control devices would likely control the particulate characteristics

that most affect the opacity to mass concentration correlation sufficiently enough that a

transmissometer could be used as a mass monitor.
2-4

In a 1975 journal article, John Nader, Chief of the Stationary Source Measurements

Research Section of the EPA’s National Environmental Research Center, published a summary of

the current technologies for continuously monitoring PM emissions. In his paper, he discussed

electromagnetic techniques, beta attenuation techniques, optical techniques (both light attenuation

and light scatter), and electrical techniques. At the time his paper was published, most of the

instruments were prototypes. Nader concluded that a performance specification for particulate

mass concentration monitors would be developed in the near future.

In a 1979 publication from the EPA’s Environmental Sciences Research Lab, Conner,

Knapp, and Nader (1979) presented, in addition to other things, the existence of a functional

relationship between in-stack transmissometer-measured opacity and mass concentration of PM

emissions. This examination was done at Portland cement plants and oil-fired power plants. Their

paper contained the following equation that demonstrates that the opacity-mass concentration

relationship depends on the chemical and physical characteristics of the particles, as well as the

pathlength of the opacity measurement:

O e

AC

= −

−

1

l

where:

O = opacity

A = attenuation per unit path length per unit mass concentration

C = mass concentration

R = pathlength of opacity measurement

Tests to correlate opacity and mass concentration were done at three cement plants; two

used the wet-process rotary kiln with PM emissions controlled with ESPs and one used the dryprocess rotary kiln with a baghouse for PM emissions control (Conner, Knapp, and Nader, 1979). 

Opacity measurements were made with either a Lear Siegler RM4 or RM41P. Mass

concentrations were determined by EPA Reference Method 5. The results of their study indicate

that the light attenuation coefficient of PM emissions at cement plants is linearly related to the PM

mass concentration for both wet and dry processes. However, for the correlation done at actual

stack conditions, the slopes of the curves (attenuation coefficient/mass concentration) were

distinctly different for the wet process (1.55±0.02 m-1/g/m3) and the dry process 
2-5

(0.92±0.08 m-1/g/m3). Note, the correlation for the process controlled by the baghouse was

developed from only three data points within a narrow opacity range of about 6 percent to

8 percent. This suggests caution when interpreting these results.

Other tests to correlate opacity and mass concentrations were done at three oil-fired

power plants (Conner, Knapp, and Nader, 1979). The boilers had no PM emission control

equipment installed. Two plants combusted low-sulfur oil, and the boilers were fired at excess

oxygen levels between 1.5 percent and 3.0 percent. The third plant combusted high-sulfur oil,

and the boiler excess oxygen was at 0.2 percent. Opacity measurements were made with a Lear

Siegler RM41P. Mass concentrations were determined by EPA Method 5. The data from the

two similar plants were combined, and a light attenuation coefficient per mass concentration ratio

(at actual stack conditions) of 0.43 m-1/g/m3 was calculated. This relationship was calculated

over an opacity range from about 2.5 percent to 6.7 percent and forced through the origin. The

data for the high-sulfur, oil-fired boiler produced a light attenuation coefficient per mass

concentration ratio (at actual stack conditions) of 0.20 m-1/g/m3. This relationship was

calculated from data collected during two sampling efforts 6 months apart covering an opacity

range from about 6 percent to 11 percent. This relationship was also forced through the origin. 

The authors stated their reason for the difference in the correlations as follows: the low excess

oxygen combustion produced a greater portion of particles (unburned carbon) in the large size

fraction (mean diameter of about 3 μm compared to less than 0.3 μm) and therefore, as expected,

produced lower opacity readings.

In a 1980 article, Uthe published the results of an evaluation of a relatively inexpensive

infrared transmissometer used as a PM mass concentration monitor. Uthe’s results showed that

the extinction-to-mass concentration for a given aerosol type is dependent on particle size within

the visible light spectrum but nearly independent of particle size at the infrared wavelength. Uthe

tested his IR transmissometer in an aerosol chamber with three distinct particle size ranges:

0-2.5 μm, 2.5-5 μm, and 5-10 μm. His particles were composed of fly ash, iron oxide, and silica. 

For fly ash particles in the size range of 0-10 μm, the IR extinction to mass concentration ratio

varied by a factor of 1.6 while the variability for visible light was a factor of 4.4. For silica

particles, the IR extinction to mass concentration ratio was nearly constant while the variability
2-6

for visible light was about a factor of 3. Personal communication with Uthe revealed that the IR

transmissometer was never evaluated on a real emission source.

During a 1-year period in 1976-1977, a group of researchers from the Industrial Research

Institute, University of Windsor (Gnyp et al., 1978), conducted a field evaluation of five different

PM monitors. The test was done at a secondary lead smelter. The stack exhaust consisted of

particulate from uncontrolled lead alloying kettles and a reverberatory furnace controlled with a

fabric filter. Thirty-two PM test runs were conducted over a 9-month period from June 4, 1976

to March 7, 1977. Twelve tests accounted for the reverberatory furnace mode of operation (i.e.,

controlled emissions). The remaining 20 tests were conducted while refining processes were in

progress (i.e., uncontrolled emissions). The arithmetic mean particle diameter of the baghouse

emissions was 0.43 μm with a standard deviation of 0.13 μm. The arithmetic mean particle

diameter of the emissions from the lead kettles was 18.9 μm with a range from 0.05 μm to 150

μm. The particulate consisted primarily of lead, tin, and zinc. The results of the PM monitor

evaluation are summarized in Table 2-2.

TABLE 2-2. PM MONITOR EVALUATION RESULTS

AT A SECONDARY LEAD SMELTER

PM monitor Results

Lear Siegler RM41

transmissometer

Impossible to correlate all 32 tests to one curve

Three distinct linear correlations were evident

Most reliable of all monitors tested

Not applicable for sources where process variations cause changes in PM

size, color, or refractive indices

Contraves Goertz with

RAC transmissometer

Impossible to correlate all 32 tests to one curve, basically the same

results as the RM41

Not capable of detecting large particles greater than 25 μm in diameter

Environmental Systems

Corporation PILLS V light

scatter monitor

Correlation was relatively independent of changes in particle size, color,

and refractive index

More useful than the best transmissometers

Some of the variability in the data was attributed to changes in absorptive

components of refractive indices
TABLE 2-2. (CONTINUED)

PM monitor Results

2-7

IKOR 2710 charge transfer Limited sensitivity to particles smaller than 1 μm diameter; particles must

contact sensor

At the stack conditions, only particles larger than 4 μm in diameter made

contact with the sensor surface

Orienting the sensing element with its axis perpendicular to the flow did

not improve the contact of small particles

Research Appliance Co.

(RAC) beta gauge monitor

Expected a single correlation curve, but instrument was more sensitive to

smaller particles less than 1 μm in diameter

Substantial amounts of PM were recovered from the sampling system at

the end of the test program

Experienced many operational breakdowns, only functioned for 13 test

runs

The developmental testing of PM CEMSs in Germany started during the 1960s when the

TÜV-Rheinland (the German “technical inspection agency,” a not-for-profit organization similar

to Underwriters Laboratories in the United States) first investigated continuous PM monitors

(Draft Technical Support Document, 1996). The early tests involved transmissometers. Initially,

eight devices were evaluated, but all failed to perform to the satisfaction of TÜV. After

improvements were made, TÜV Rheinland certified two transmissometers in 1968 (Peeler et al.,

1995). The first certification of a PM CEMS (a transmissometer) was issued in 1974 and

prompted the German Federal Law of Immission Protection to require continuous monitoring of

PM emissions at power plants. A further reduction in particulate emissions was required with the

passage of the First Regulation of General Administration Procedures to the Federal Law of

Immission Protection on February 27, 1986. This latter act spurred the use of more sensitive

monitors to measure PM emissions from well-controlled waste incinerators. 

As previously noted, during the early period of continuous PM monitoring in Germany,

transmissometers were used to measure extinction (b = 2.303 * log(1/T) / PL) and were

correlated to PM concentration. A key advantage of using extinction rather than opacity is that

extinction relates linearly to particulate matter. Extinction also results in an output that is more

sensitive to increases in PM concentration at low levels. The transmissometers were typically
2-8

operated at two measuring ranges, 0-9 percent or 0-33 percent opacity. For a 1-meter pathlength,

a transmissometer’s minimum quantifiable PM concentration is about 30 mg/acm (Peeler et al.,

1995). From 1968 through 1985, approximately 1,000 to 2,000 transmissometers, measuring

extinction, were installed on all types of sources in Germany measuring PM emission limits in the

range of 30 mg/m3 to 150 mg/m3. Furthermore, approximately 5,000 transmissometers,

measuring opacity, were installed for monitoring control equipment performance. Then, as PM

concentrations decreased to levels too low to be accurately measured with transmissometers, use

of the light scattering type PM CEMS came into favor. Light scatter monitors are 100 to 1,000

times more sensitive than transmissometers. A light scattering monitor’s output is directly

proportional to PM concentration, and thus inversely proportional to a transmissometer output

(i.e., it cannot be used as a substitute for an opacity monitor). Since 1986, light scatter monitors

represent about 80 percent of new PM monitors installed in Germany (Peeler et al., 1995). 

During the 1990s, many existing transmissometers were replaced with light scattering type PM

CEMS as facilities updated their pollution control equipment to come into compliance with more

stringent regulations. The suitability testing for transmissometers is governed by VDI Guideline

2066, Part 4. The suitability testing of light scattering type PM CEMSs is governed by VDI

Guideline 2066, Part 6. 

2.3 CURRENT EUROPEAN EXPERIENCE

In Germany, a specific model PM CEMS must pass a suitability test and be approved by

the Federal Environmental Agency before it can be installed and used as a PM CEMS to meet

regulatory monitoring requirements. The suitability test follows guidelines in a Standard Practice

regarding the monitoring of emissions (Standard Practice, 1990, revised June 8, 1998). The

source-specific acceptance of a suitability test is based on a hierarchy of difficulty in passing the

test; incinerators are most difficult, followed by coal, oil, and gas-fired plants. Thus, if a monitor

passes suitability for an incinerator, the monitor is also approved for all the less difficult sources. 

However, sources such as cement kilns and metal recovery furnaces are separate and require their

own suitability test (Draft Technical Support Document, 1996). The specifications that a PM

monitor must meet to gain approval are presented in Table 2-3. The suitability test consists of

both a laboratory evaluation and a field evaluation. In most cases, the suitability test is done by
2-9

the TÜV branch in Rheinland; however, TÜV is not the only organization that can do the

suitability test. 

TABLE 2-3. GERMAN SUITABILITY TEST SPECIFICATIONS FOR APPROVAL

Test Specificationa

Normative conditions Suitability testing must be done according to guidelines in VDI 2449

part 1 dated February 1995.

Endurance test Conduct an endurance test for at least 3 months. If possible, conduct

the test at a single test site for a continuous period.

Analytical function In suitability testing, the relationship between the instrument reading

and mass concentration from a reference measuring method must be

determined by regression analysis. Each instrument must be supplied

with a characteristic curve plotted by the manufacturer.

Protection from changing

settings (Security)

The instrument and control units must be secured against

unauthorized or inadvertent change during operation.

Zero and reference point

position

The zero point should be 10 percent to 20 percent of full scale on the

instrument display and recording device. The reference point should

be 70 percent to 90 percent of full scale.

Full scale readout range The readout range should equal:

• 2.5 to 3 times the applicable emission limit for a coal-fired

furnace

• 1.5 times the applicable emission limit for a waste incinerator

Measured value output The instrument must have two readout channels.

Status signals The instrument must have status signals for

1. Operation

2. Service

3. Malfunction

Availability The instrument must achieve 90 percent data availability during

continuous operation and 95 percent availability during the

evaluation test.

Maintenance interval The instrument’s maintenance period must be at least 8 days (i.e., no

operator intervention for at least 8 day intervals). Maintenance

period is determined during the field evaluation.

Reproducibility - for all PM

CEMS since 1998

RD$ 50 for a measuring range $ 20 mg/m3

RD$ 30 for a measuring range < 20 mg/m3

Complete system The suitability test covers the entire CEMS.
TABLE 2-3. (CONTINUED)

Test Specificationa

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Normal operating conditions Evaluate the instrument under the following conditions over the

manufacturer’s recommended range for each:

1. Supply voltage variation

2. RH in ambient air

3. Liquid water in the air

4. Vibration and shock

Automatic readjustment For instruments with self-testing of proper operation and automatic

readjustment, test these features in the evaluation test. If an

adjustment range of ±6 percent of span is exceeded during

autocorrection, an alarm must be given.

Ambient temperature range For instruments installed unprotected from ambient conditions, the

instrument must operate over the range of 

-20oC to 50oC. For temperature-controlled installations, the

instrument must operate over the range of 5oC to 40oC.

Test instrument in a climate chamber.

Effect of sample gas flow For instruments using a bypass for sampling, the effect of changes in

sample gas flow rate on the measured signal must not exceed

±1 percent of span. Neither the total volumetric flow sampled during

the operating cycle nor the dilution air volumetric flow may deviate

from the expected value by more than ±8 percent.

Multicomponent instrument Each component must fulfill the requirements, even when all

measuring channels are operating simultaneously.

Drift between servicing

intervals

The zero point must not drift more than

±2 percent of full scale for range $ 20 mg/m3

±3 percent of full scale for range < 20 mg/m3

The reference point must not drift more than

±2 percent of the reference value for range $ 20 mg/m3

±3 percent of the reference value for range < 20 mg/m3

Linearity The difference between the actual value and the reference value must

not exceed ±2 percent of full scale (for a 5 point check).

Contamination check If the measurement principle depends on optical methods, the

instrument must check for optical surface contamination during

operation. Use clean purge air to keep optical surfaces clean.

Outward migration of

measurement beam

If the measurement principle is based on optical methods, any

impairment due to outward migration of the measurement beam must

be stated and must not exceed 2 percent of full scale in an angular

range of ±0.3E.
TABLE 2-3. (CONTINUED)

Test Specificationa

2-11

Automatic correction of zero

and reference points

The instrument must automatically initiate and record the zero and

reference points at regular intervals. For instruments with automatic

zero point correction, the correction amount must be recorded as a

measure of contamination.

Exhaust gas volume For extractive instruments, the sample volume must be within

±5 percent of the set point.

Dead time, setting time (similar

to cycle time)

Measure the dead time to include: response time, analysis time, and

reporting time.

a

Specifications derived from TÜV Suitability Test Reports for the Sigrist CTNR, Verewa F-904, and Durag D-R

300-40.

After a PM CEMS is installed, its output is correlated to manual gravimetric particulate

data. The stability of the correlation is checked by conducting additional manual gravimetric 

tests at 3- to 5-year intervals, depending on the source type. A linearity check of the instrument’s

response is also done annually (Peeler et al., 1995). The TÜV has guidelines for establishing

correlation curves. Most of the manual particulate emissions measurements are done by an

isokinetic, in-stack filter test method (similar to Method 17 - VDI 2066, Part 7); however, instack sampling is limited to stacks with no entrained water droplets. The following guidelines are

used for a correlation test in Germany (personal communication with Dr. Wolfgang Jockel, TÜV,

Rheinland):

• The test program consists of 12 to 20 test runs.

• A few paired train test runs are completed to demonstrate an ability to maintain precision.

If the testing team has experience at a source, they do not do any test runs with paired

trains.

• Test runs are short, no longer than 30 minutes (this is so that any variability in PM

concentrations is noticeable and not averaged out by a long test run).

• If the facility cannot achieve any variability in PM concentration, the correlation test

program is stopped after 6 test runs. Typically, waste combustion facilities have extensive

air pollution control systems (e.g., a water spray drier for cooling, a fabric filter, an acid

gas (HCl) scrubber, a lime scrubber SO2 control, a dual catalyst SCR and dioxin oxidizer,
2-12

and an activated charcoal “police” filter), and the particulate emissions cannot be

artificially adjusted to obtain a range of PM concentrations.

In cases with emissions that are very low relative to the limit, the guidelines allow

extrapolation of the correlation; however, data measured beyond the correlation range trigger

only additional testing, not noncompliance. For a correlation data set with only a cluster of data

points very much below the emission limit, the emission limit becomes related to the mA signal of

the PM CEMS. For example, if a PM CEMS output during the testing ranged from 4 mA to

4.5 mA, no 30-minute average may exceed 4.5 mA during plant operations. If an average

exceeds 4.5 mA, a new correlation test that includes values above 4.5 mA would have to be done. 

For a limited correlation data set with little variability in PM concentration, the German guidelines

require the use of a hypothetical zero point (i.e., 4 mA = 0 mg/m3) in the correlation data set for

an in-situ light scatter type PM CEMS using little or no purge air and for an extractive type PM

CEMS (i.e., either beta gauge or light scatter).

The German approach to using a PM CEMS is to build the statistical uncertainty of the

PM CEMS measurement (due to the factors of particle composition and size distribution) into the

emission limit value. The correlation relation is not required to achieve a specific statistical

accuracy (e.g., a confidence interval #10 percent at the emission limit value) to be approved. This

approach is illustrated in the following example. A municipal waste combustion facility has a base

PM emission limit (EL) of 30 mg/dscm. Assume a specific source’s PM CEMS correlation has a

confidence interval (CI) at the emission limit of 4 mg/dscm (13 percent) and a tolerance interval

(TI) at the emission limit of 11 mg/dscm (37 percent). Then, that specific source would have the

following PM limitations (from personal communication with Dr. Wolfgang Jockel, TÜV,

Rheinland):

• No 30-minute average may exceed: 2*EL + TI = 60 + 11 = 71 mg/dscm.

• 97 percent of the annual 30-minute averages may not exceed: 1.2(EL + CI) = 36 + 5 =

41 mg/dscm.

• No daily average may exceed: EL + CI = 30 + 4 = 34 mg/dscm.

Even with the uncertainty in the PM CEMS measurement, the correlation relationship can still be

used as a basis for compliance. Traditionally, the EPA regulations have taken this uncertainty into

account when a CEMS-based standard is adopted.
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In addition to the suitability testing specifications that exist in Germany, the International

Standards Organization (ISO) has developed standards for PM CEMSs. The ISO committee

TC146/SC1/WG1 finalized ISO 10155 “Stationary Source Emissions - Automated Monitoring of

Mass Concentrations of Particles - Performance Characteristics, Test Methods, and

Specifications” on April 1, 1995. ISO 10155 specifies conditions and criteria for the automated

monitoring of PM mass concentrations in stationary sources. The specifications are general and

not limited to a specific measurement principle or system. The Central European Normalization

(CEN) Committee TC264/WG5 has developed requirements applicable to continuous PM

monitoring. CEN adopted ISO 10155 for hazardous waste incinerators.

The Environment Agency (EA) in the United Kingdom (UK) has established a monitoring

certification scheme (MCERTS) for all CEMSs, including PM CEMSs. The MCERTS program

is similar to the program used in Germany and began on April 22, 1998. The performance

standards have been specified for the following sources:

• Large combustion plants

• Municipal and hazardous waste combustors

• Solvent-using processes

The instrument performance standards are based on relevant sections of several ISO and

CEN standards. These standards are published as EA standards under the MCERTS program. 

Instrument testing is done in two parts; laboratory tests and a 3-month field evaluation. The

standards cover the performance characteristics presented in Table 2-4.

TABLE 2-4. MCERTS PM CEM EVALUATION CHARACTERISTICS

Laboratory test Field evaluation

Use a wind tunnel test with well characterized and

reproducible particle-size distribution with mass

concentration variable from 0 to 500 mg/m3 at a

gas flow velocity of 1.5 to 50 ft/s

Accuracy - as calibrated according to ISO 10155

Response time Reproducibility from two identical PM CEMS

Calibration to PM generated in wind tunnel Zero and upscale drift during the field test period -

average of daily drifts over a month

Linearity of PM CEM response to changes in PM

concentration at 5 levels

Data availability
TABLE 2-4. (CONTINUED)

Laboratory test Field evaluation

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Cross-sensitivity to gases, velocity changes at a

fixed PM concentration, and particle size changes

Maintenance interval - time over which the zero

and upscale drifts remain within specification

Establishment of a lower detection limit

Repeatability of the PM CEM’s output to a

continuous PM concentration in tunnel

Change in zero value to variations in

• Ambient humidity

• Ambient temperature

• Vibration

• Mechanical shock

• Magnetic field

• Aging
3-1

3.0 ANALYTICAL PRINCIPLES

Five analytical principles used in instruments to measure PM concentrations are described

below. These principles are light scattering, beta attenuation, probe electrification, light

extinction, and optical scintillation.

3.1 LIGHT SCATTERING

Light is both absorbed and scattered by particles in the path of the light. Scattering is due

to reflection and refraction of the light by the particle. The amount of light scattered is based on

the concentration of particles and the properties of the particles in the light’s path (e.g., the size,

shape, and color of the particles). If the wavelength of the incident light is much larger than the

radius of the particle, a type of scattering called “Rayleigh” scattering occurs. Rayleigh scattering

causes the blue color of the sky because visible sunlight is scattered by very small particles and

gases in the upper atmosphere. If the wavelength of the incident light is about the same size as

the radius of the particle, a type of scattering called “Mie” scattering will occur. Mie scattering

causes the haze seen on a hot summer day and the reduction of visibility by car headlights in a fog. 

A light scatter type instrument measures the amount of light scattered in a particular

direction (i.e., forward, side, or backward) and outputs a signal proportional to the amount of

scattering material (e.g., particulate matter) in the sample stream. The PM concentration is

derived by correlating the output of the instrument to manual gravimetric measurements. In a

scatter light instrument, a collimated beam of visible or near infrared (IR) light is emitted into a

gas stream. The light is scattered by particles in the light path (i.e., Mie scattering), and the

receiving optics focus an area of that light onto a detector that generates a current proportional to

the intensity of light it receives. The angle of the source to the receiving optics and the

characteristics of the optics determine the volume of space from which the scattered light is

measured. 

Some components included in these instruments to minimize the effect of interference and

degradation of the light source are: (1) the use of a pulsed light and (2) parallel measurement of

the light source intensity. The use of the pulsed light source limits the possibility that light from

some other source (e.g., ambient light) will be measured, because the instrument only measures

the reflected light while the instrument light source is on. The parallel measurement of the light
3-2

source intensity accounts for degradation of the light source because a reference of the source

intensity is measured along with each scattered light measurement.

3.2 BETA ATTENUATION 

When beta rays pass through a material, they can be absorbed, reflected or pass directly

through. The attenuation of intensity in beta rays is proportional to the amount of material

present. The attenuation through most materials is relatively consistent and is based on the

electron density of the material (calculated by dividing the atomic number by the atomic mass). 

The attenuation for most materials is about 0.5, except for hydrogen and heavy metals. Beta

attenuation has been used in production lines as a quality control check of product thickness for

more than 40 years. For example, in the production of cellophane plastic wrap, a beta gauge is

used to ensure that the thickness of the cellophane remains within specification.

The principle behind beta attenuation particulate sampling instruments (beta gauge) is that

energy is absorbed from beta particles as they pass through PM collected on a filter media. Beta

gauge instruments have been designed to take advantage of this scientific principle to

monitor/measure PM concentrations. The attenuation due to only the PM is measurable if a

baseline beta count through just the filter can be established prior to sampling. The difference

between the baseline beta count and the beta count after sampling is directly proportional to the

mass of PM in the sample. 

The two main components of a beta attenuation measuring system are the beta source and

the detector. The beta source must be selected so that: it has an energy level high enough for the

beta particles to pass through the collection media (i.e., the filter tape) and the particulate, it has

enough source material so that a high count rate is present, it is stable over long periods of time,

and it does not present a danger to the health of personnel that come into contact with the

instrument. The source of choice has been Carbon-14 because: it has a safe yet high enough

energy level, it has a half-life of 5,568 years, and it is relatively abundant. Many different types of

detectors can quantify beta particle counts, but the ones most widely used are the Geiger Mueller

counter or a photodiode detector. 

The beta gauge works by measuring beta counts before and after collecting PM on a filter

media. The instrument will measure a clean area of the filter media for a fixed period to determine

the baseline (e.g., 2 minutes), then it will advance that area of the filter to a sampling apparatus
3-3

for another set period of time (e.g., 8 to 9 minutes), and finally return that area of the filter to the

detector for the same period used to establish the baseline reading. The difference in the beta

count can be directly correlated to particulate mass through calibration of the instrument using a

filter media containing a known mass of a particulate-like material.

The beta gauge instrument is designed to provide a mass concentration. The instrument

measures the volume of gas extracted from the stack/duct for each sample interval and calculates

mass concentration in the specified units (e.g., mg/dscm).

3.3 PROBE ELECTRIFICATION (TRIBOELECTRIC EFFECT)

Probe electrification takes advantage of the fact that all particles have a charge. 

Electrostatic charges from the friction of particles contacting a probe will electrify the probe (i.e.,

a small current is produced in the probe). This is called triboelectricity. Another applicable

mechanism is based on a small current being induced in the probe when charged particles pass

near a probe.

A triboelectric particulate monitoring device measures the direct current (DC) produced

by the charge transfer when particles strike the probe. The DC is measured by an electrically

isolated sensor probe that is connected to amplification electronics. Multiple particle strikes

create a small flow of current through the instrument; current is proportional to the momentum

(mass times velocity squared) of the particles. Amplification electronics convert the current to an

instrument output signal. Monitors that rely on inducing a current in the probe, rather than

particle contact with the probe, work similarly except an alternating current (AC) is measured. 

Because the signal produced by these monitors may be affected by several factors, the

instrument output must be correlated to manual gravimetric measurements. Some of the primary

factors that may affect the relationship between particle mas and the monitored signal are particle

velocity for triboelectric devices, particle characteristics (e.g., composition and size), and particle

charge. Probe electrification does not work well in wet gas streams with water droplets or when

the particles are subject to a varying electrical charge. The AC component of the induced current

is being used to minimize the effect of velocity on the measurement.

3.4 LIGHT EXTINCTION (TRANSMISSOMETER)

Light extinction is a common method in use today; the instruments that incorporate this

technology are referred to as transmissometers or opacity monitors. These instruments measure
3-4

the loss of light intensity across a particulate laden gas stream as a function of Beers-Lambert’s

Law. The intensity of the light at the detector, I, is compared with the reference light intensity,

I

o

, to give the transmittance, T = I/Io. Transmittance can be converted to opacity, Op = 1-T, or

optical density, D = log(1/T). The loss of light intensity can be correlated to particulate mass

concentration measured by manual gravimetric sampling. In general, the measurement sensitivity

of transmissometers is not fine enough to detect small changes in PM concentration. For

example, in a 2 meter diameter stack (4 m path length) the smallest emission standard that should

be measured with a transmissometer is 15 mg/m3 (personal communication with Dr. Wolfgang

Jockel, TÜV Rheinland, email dated March 20, 2000).

The basic operational principle of these instruments is that a collimated beam of visible

light is directed through a gas stream toward receiving optics. The receiving optics measure the

decrease in light intensity, and the instrument electronics convert the signal to an instrument

output. An instrument incorporating the components described in the previous sentences would

be considered a single pass system. For better resolution and higher accuracy, a dual-pass

transmissometer and a modulating light source are used. The dual-pass transmissometer (with a

reflector mirror on the opposite side of the stack from the light source) allows all of the

instrument electronics to be incorporated into one unit. A high frequency modulation of the light

source limits the possibility of interference because the instrument only reads the loss of light

while the light source is on. When an LED light source is used, electronic modulation of the light

(instead of chopping) is possible. Incorporating the light source and detector into one instrument

also allows direct measurement of the loss of light by comparison of the source intensity and the

loss of light at the same time. This helps prevent inaccurate readings due to the degradation of

the light source intensity (a common problem in basic transmissometers). 

A transmissometer used as a PM CEMS should use a red or near infrared light source, and

not the white light source used on traditional opacity monitors (see Section 2.2, the discussion of

Uthe’s work, for an explanation). Some manufacturers have started using a green LED to

monitor both opacity and PM concentration simultaneously. Furthermore, the opacity monitor’s

correlation to PM concentration as measured by the Reference Method should be done versus

opacity or optical density.
3-5

3.5 OPTICAL SCINTILLATION

Optical scintillation, like light extinction, utilizes a light source and a remote receiver that

measures the amount of received light. The difference is that the scintillation monitor uses a wide

beam of light, no focusing lenses, and the receiver measures the modulation of the light frequency

due to the movement of particles through the light beam and not the extinction of light. The

principles at work here are that the particles in a gas stream will momentarily interrupt the light

beam and cause a variation in the amplitude of the light received (scintillation). The greater the

particle concentration in the gas stream the greater the variation in the amplitude of the light

signal received. The scintillation monitor must be calibrated to manual gravimentic measurements

at the specific source on which it is installed.
4-1

4.0 SUMMARY OF KNOWN PM CEMS

Based on the analytical measurement principles presented in Section 3.0, instrument

manufacturers have developed monitors to continuously measure PM concentrations in source

emissions. Most of these monitors measure a property of the particulate matter in the stack (e.g.,

scatter of light, transfer of charge, or modulation of transmitted light) and the concentration is

then inferred based on a correlation to manual gravimetric samples. In contrast, the beta

attenuation monitors produce results on a concentration basis from the mass of particulate matter

collected on a filter divided by the volume of gas sampled through the filter.

This section presents a summary of most of the monitors that are commercially available

from manufacturers as “off-the-shelf” PM CEMS, as listed below. Mention of specific

manufacturers equipment is not an endorsement of the product by the EPA. These descriptions

are solely for informational purposes.

4.1 Durag F904K Beta Attenuation

4.2 Environment S.A. 5M Beta Attenuation

4.3 Mechanical Systems Inc BetaGuard PM Beta Attenuation

4.4 Sigrist KTNR and CTNR Extractive Light Scatter

4.5 Durag DR-300-40 In-situ Light Scatter

4.6 Environmental Systems Corporation P5 In-situ Light Scatter

4.7 Sick Inc. RM210 In-situ Light Scatter

4.8 Sick Inc. FW 100 and FWE 200 Light Scatter

4.9 Grimm Technologies 6300 In-situ Light Scatter

4.10 Monitor Labs 300L In-situ Light Scatter

4.11 BHA Group CPM 5000 Scintillation

4.12 PCME Scintilla SC600 Scintillation

4.13 Insitec TESS In-situ or Extractive Laser Light Extinction-Scatter

4.14 PCME DustAlert 90 Electrostatic Induction

4.15 Auburn International Triboguard III or II In-situ Triboelectric

4.16 Codel StakGard Triboelectric Dust Monitor

4.17 Opacity/Transmissometers
4-2

Many of these PM CEMSs have been in use for 10 or more years while others are

relatively new. Source specific applicability of each of these PM CEMSs is presented in

Section 7.0, PM CEMS Implementation.

4.1 DURAG F904K BETA ATTENUATION

The F904K extracts a sample from the stack, transports the sample to the instrument

through a heated line, and deposits PM on a filter tape during user-selected sampling periods

(e.g., 4 to 8 minutes). Before and after each sampling period, the filter tape is moved between a

carbon 14 beta particle source and Geiger-Mueller detector. The amount (in units of mg) of PM

on the filter is determined by the reduction in transmission of beta particles between the readings

for the dirty tape and the clean tape. This instrument measures the sample gas volume on a dry

basis, and therefore outputs PM concentration in units of mg/dscm. The F904K samples

isokinetically at normal stack gas velocity, but isokinetic sampling is not actively maintained (i.e.,

when the stack gas velocity decreases, the F904K’s sampling rate remains constant creating a

superisokinetic sampling condition and a low bias to the measured PM concentration). To

minimize particulate loss in the sampling system, the F904K introduces dilution air after the

sampling nozzle and samples at a high rate of about 3,000 liters per hour (~ 1.75 cfm); however,

this sampling rate can be modified as needed for site-specific conditions. The measuring range is

determined by the length of the sampling period, but the instrument can only accommodate up to

6 mg to 8 mg of particulate deposited on the filter tape during each sampling period. If too much

particulate is collected during a sampling interval, a high vacuum is created, and the sampling is

curtailed. This instrument does automatic zero and upscale drift checks to meet daily QC check

requirements. 

The distance between the probe and instrument is recommended to be less than 20 feet. 

The footprint of the F904K is approximately 30 inches by 48 inches with clearance needed in front

and behind the case to open the doors. The instrument weighs about 400 pounds. A single, 6-

inch port is needed for the probe installation into the stack. This instrument also requires a supply

of high-pressure air and 230V of electrical power.

The F904 version was approved by the German TÜV in 1990 for all sources. The F904

version was evaluated by the EPA/OSW at the long-term field test at the DuPont Experimental

Field Station liquid waste incinerator and by Eli Lilly (only during phase II) at a liquid waste
4-3

incinerator. The F904K was evaluated by the EPA/OAQPS at a coal-fired boiler and by the

Department of Energy at the radionuclide incinerator at Oak Ridge National Lab. The instrument

is relatively insensitive to changes in the PM composition and PM properties and is not affected

by the presence of condensed water droplets in the gas stream. Although the instrument output is

in units of mg/dscm, a correlation to manual gravimetric data is recommended to account for any

particulate stratification at the sampling point.

4.2 ENVIRONMENT S.A. 5M BETA ATTENUATION

The Beta 5M extracts a sample from the stack through a heated probe and deposits PM on

a filter tape during user defined sampling periods (e.g., 4 to 8 minutes). The instrument mounts

onto the end of the probe and thus does not have a sampling line. At the end of each sampling

period, the filter tape is moved between a carbon 14 beta particle source and a detector. The

amount (in units of mg) of PM on the filter is determined by the decrease in beta particles passing

through the dirty tape as compared to the clean tape. This instrument measures the sampled

volume on a wet basis, and therefore, outputs PM concentration in units of mg/acm. Since the

sampled volume is measured on a wet basis, the instrument is susceptible to clogging in the

volume measurement lines when used in high-stack-gas-moisture environments. The Beta 5M

maintains isokinetic sampling with real-time )P and temperature measurements. Before the

analysis is done at the end of each sampling period, the probe nozzle is closed, opened, and closed

again creating a vacuum to re-entrain any PM deposited in the probe. The measuring range is

determined by the length of the sampling period, but the instrument does have a lower detection

limit. Currently, this instrument does not do automatic zero and upscale drift checks, but the

manufacturer is reportedly developing this capability. 

The footprint of the Beta 5M is a box attached to the probe with dimensions of

approximately 15 inches by 30 inches by 30 inches that hangs from a support frame attached to

the stack. The instrument weighs about 180 pounds. A single, 6-inch port is needed for the

probe installation into the stack. This instrument also requires a supply of high-pressure air and

either 115V or 230V of electrical power.

The Beta 5M was evaluated by the EPA/OSW at the long-term field test at the DuPont

Experimental Field Station liquid waste incinerator, by Eli Lilly at a liquid waste incinerator, and

by the Department of Energy at the radionuclide incinerator at Oak Ridge National Lab. The
4-4

instrument is relatively insensitive to changes in the PM composition and properties and is not

affected by the presence of condensed water droplets in the gas stream, except for the potential of

clogging the sample volume lines. Although the instrument output is in units of mg/acm, a

correlation to manual gravimetric data is recommended to account for any particulate

stratification at the sampling point.

4.3 MECHANICAL SYSTEMS INC. BETAGUARD PM BETA ATTENUATION

The BetaGuard PM extracts a sample from the stack, transports the sample to the

instrument through a heated line, and deposits PM on a filter tape during user-selected sampling

periods (e.g., 4 to 8 minutes). Before and after each sampling period, the filter tape is moved

between a carbon 14 beta particle source and Geiger-Mueller detector. This instrument uses a

dual beta source-detector arrangement to minimize lost sample time (i.e., sampling is occurring on

a second “spot” while a measurement is being made on the first “spot”). The amount (in units of

mg) of PM on the filter is determined by the reduction in transmission of beta particles between

the readings for the dirty tape and the clean tape. This instrument measures the sample gas

volume on both a wet and dry basis, and therefore outputs PM concentration in a variety of units. 

The BetaGuard PM actively samples isokinetically by receiving a stack gas flow rate signal from a

flow monitor. Isokinetic sampling is maintained by holding the total sample flow rate constant

and then varying the amount of dilution air that is added to the sample gas. The measuring range

is determined by the length of the sampling period and the selected nozzle size. The instrument

can measure in a range from 1 to 500 mg/dscm. If too much particulate is collected during a

sampling interval, a high vacuum is created, but, instead of aborting the sampling cycle, the

amount of PM is measured and a new sampling cycle is started. This instrument does automatic

zero and upscale drift checks to meet daily QC check requirements. Additionally, this instrument

automatically does daily sample flow rate checks.

The distance between the probe and instrument is recommended to be less than 50 feet. 

The footprint of the BetaGuard PM is approximately 12 inches by 30 inches with clearance

needed in front of the case to open the door. The instrument weighs about 350 pounds. A single,

6-inch port is needed for the probe installation in most stacks. This instrument also requires a

supply of high-pressure air and 120V of electrical power.
4-5

The BetaGuard PM has undergone field trials done by the vendor and is being evaluated

in a second Electric Power Research Institute (EPRI) field evaluation at a coal-fired boiler. The

instrument is relatively insensitive to changes in the PM composition and PM properties and is not

affected by the presence of condensed water droplets in the gas stream. Although the instrument

vendor asserts that a site specific correlation to manual gravimetric data is not needed for a

representative sample location, the EPA requires a PS-11 correlation test to account for any

particulate stratification at the sampling point.

4.4 SIGRIST KTNR AND CTNR EXTRACTIVE LIGHT SCATTER

The KTNR and CTNR (newer version) are both PM CEMSs that use the principle of

forward light scattering at 15E in the visible to near infrared light spectrum. The measuring

ranges are from 0 to 0.1 mg/dscm up to 0 to 1000 mg/dscm. These instruments extract a heated

slipstream (1 m3/min) from a single point in the stack and pass a small portion (35 lpm) through a

photometer. The extracted gas is then returned to the stack. The extraction sample rate is overisokinetic at normal stack gas flow rate. The vendor notes that over-isokinetic sampling

significantly reduces the error caused by velocity fluctuations and is an alternative to continuous

monitoring of the stack gas velocity and adjustment of the sampling rate. The KTNR and CTNR

do not perform automatic zero and upscale drift checks, but manual drift checks can be done on

the CTNR. 

The minimum space requirement for this instrument is a height of 8.5 feet, width of 5 feet,

and a depth of 3.5 feet. For outdoor installations, a shelter must be provided. Two 4-inch ports

are needed for the extraction and return probes. The electrical power requirement is 3-phase

400V and 230V. A transformer is offered to facilities that do not have the required power.

Both instruments were approved by the German TÜV for all source categories. The

KTNR was evaluated by the EPA/OSW at the long-term field test at the DuPont Experimental

Field Station liquid waste incinerator, and the CTNR was evaluated by Eli Lilly at a liquid waste

incinerator and by the Department of Energy at the radionuclide incinerator at Oak Ridge

National Lab. The instrument response can be correlated in mg/acm by comparison to manual

gravimetric data. This instrument is sensitive to changes in particle characteristics (e.g., size,

shape, and color), but because it heats the extracted sample gas to vaporize condensed water, it is

not affected by the presence of condensed water droplets in the gas stream.
4-6

4.5 DURAG DR-300-40 IN-SITU LIGHT SCATTER

The DR-300-40 PM CEMS uses the principle of side light scattering at 120E in the visible

light spectrum. This instrument’s measuring ranges are from 0 to 1 mg/m3 up to 0 to 100 mg/m3,

depending on the size of the aperture installed. It is therefore recommended for measurements of

low PM concentrations. The “sampled volume” (i.e., the volume of stack gas where the scatter of

light due to particles is detected) is located in an area 3 to 11 inches (centered at 6 inches) from

the instrument’s face. The DR-300-40 does automatic zero and upscale drift checks to meet daily

QC check requirements. 

The footprint of the DR-300-40 is a protective covering box attached to the stack with

dimensions of approximately 36 inches high by 24 inches wide by 30 inches deep. A separate

purge air blower and filter are needed near the instrument. The instrument weighs about

60 pounds, and the protective covering weighs about 15 pounds. A single, 5-inch by 12-inch port

with a supplied mating flange is needed for installation of this instrument onto the stack. If this

instrument is installed in a stack or duct less than 5 feet in diameter, an anti-reflective device (light

trap) should be installed in the opposite wall in line with the incident light. The electrical power

requirement is 110V. 

This instrument was approved by the German TÜV in 1992 for all source categories. It

was evaluated by the EPA/OSW at the long-term field test at the DuPont Experimental Field

Station liquid waste incinerator and by the EPA/OAQPS at a coal-fired boiler. The instrument

response can be correlated in mg/acm by comparison to manual gravimetric data. This instrument

is sensitive to changes in particle characteristics (e.g., size, shape, and color) and presence of

condensed water droplets in the gas stream.

4.6 ENVIRONMENTAL SYSTEMS CORPORATION P5 IN-SITU LIGHT SCATTER

The P5 uses the principle of backward light scattering at 175E in the near infrared light

spectrum. This instrument’s measuring range is 0.5 mg/acm up to 20,000 mg/acm. The

measuring volume is located 4.75 inches from the physical end of the probe that contains both the

transmitting and receiving optics. The P5 does automatic zero and upscale drift checks to meet

daily QC check requirements. 
4-7

The footprint of the P5 is a box attached to the port flange with dimensions of

approximately 18 inches high by 12 inches wide by 36 inches deep. Also, additional clearance

beyond the physical depth is needed for the drive rod (the same length as the probe). With a

3-foot probe, the instrument weighs about 160 pounds. A single, 4-inch port with flange is

needed for installation of this instrument onto the stack. If the opposite wall of the stack is less

than 48 inches away from the end of the probe, an anti-reflective device (light trap) should be

installed in the opposite wall. The electrical power requirement is 110V. 

This instrument was approved by the Korean Ministry of the Environment (non-technical

evaluation) for use as a source PM monitor. This instrument was evaluated by the EPA/OSW at

the long-term field test at the DuPont Experimental Field Station liquid waste incinerator and by

the EPA/OAQPS at a coal-fired boiler. It is also part of a second EPRI field evaluation at a coalfired boiler. The prototype to this instrument was evaluated at a secondary lead smelter by the

University of Windsor in 1976-1977. The instrument response can be correlated in mg/acm by

comparison to manual gravimetric data. Since this instrument measures in the near infrared, it is

less sensitive to changes in particle size, and it has a roughly constant response to particles in the

0.1 to 10 μm range. The P5 will measure condensed water droplets in the gas stream as

particulate.

4.7 SICK INC. RM210 IN-SITU LIGHT SCATTER

The RM210 uses the principle of side light scattering at 90E in the visible light spectrum. 

This instrument is ideally suited for measuring extremely low PM concentrations in the range of

0.0001 mg/acm up to 200 mg/acm. This instrument is available in the following three versions

depending on the needed penetration of the sampled volume: 

• Version 1, the sampled volume is 0.5 to 7 inches from the instrument’s face,

• Version 2, the sampled volume is 6.7 to 27.5 inches from the instrument’s face, and

• Version 3, the sampled volume is 13.4 to 63.8 inches from the instrument’s face.

The RM210 does automatic zero and upscale drift checks using light attenuators. This instrument

is essentially the same size and shape as the Durag DR-300-40.

This instrument was approved by the German TÜV for all source categories, and it was

evaluated by the EPA/OSW at an early, short-term field test. The instrument response can be

correlated in mg/acm by comparison to manual gravimetric data. This instrument is sensitive to
4-8

changes in particle characteristics (e.g., size, shape, and color) and the presence of condensed

water droplets in the gas stream.

4.8 SICK INC. FW 100 IN-SITU AND FWE 200 EXTRACTIVE LIGHT SCATTER

The Sick FW 100 and FWE 200 are new, state-of-the-art PM CEMS that use the principle

of forward light scattering at 15E using a red laser light source. The FW 100 measures particulate

concentrations in-situ with a 31.5-inch probe. The FWE 200 extracts stack gas using an eductor

at over-isokinetic conditions, heats the sample gas in a thermal cyclone, then guides the sample

gas to the measurement cell where the PM concentration is measured with the FW 100 probe. 

The sample gas is then deposited back into the stack. These instruments have two measuring

ranges: 0 to 5 mg/acm and 0 to 200 mg/acm with a resolution of 0.1 mg/acm. 

The footprint for the FWE 200 is two boxes (a measurement and control cell and a blower

unit) with dimensions of approximately 33 inches high by 30 inches wide by 16 inches deep and

22 inches high by 22 inches wide by 11 inches deep. For outdoor installations, a cover is needed

for the blower unit. The measurement and control cell weighs about 150 pounds and the blower

weighs about 30 pounds. One 4-inch port is needed for the probe. The electrical power

requirement is 115 or 230V. 

The FWE 200 is being evaluated by TÜV for type certification. The instrument response

can be correlated in mg/acm by comparison to manual gravimetric data. This instrument is

sensitive to changes in particle characteristics (e.g., size, shape, and color), but because it heats

the extracted sample gas to vaporize condensed water, it is not affected by the presence of

condensed water droplets in the gas stream.

4.9 GRIMM TECHNOLOGIES 6300 IN-SITU LIGHT SCATTER

The Model 6300 uses the principle of backward light scattering in the red light spectrum

(660 nm). An electronically modulated laser-diode is the light source. Since this instrument uses

a laser-light, a light trap must be installed on the opposite side of the stack to prevent

backscattering from reflection of the light on the opposite wall. This instrument’s measuring

range is 0 to 1 mg/dscm up to 0 to 10,000 mg/dscm. The instrument contains both the

transmitting and receiving optics within a single box. The Model 6300 does not do automatic

zero and upscale drift checks to meet daily QC check requirements, these must be done manually. 
4-9

The footprint of the Model 6300 is a box with dimensions of approximately 8 inches by

6 inches by 10 inches attached to a 3-inch port flange. The instrument assembly weighs about

30 pounds. The electrical power requirement is 110V. 

This instrument was tested and approved by the German TÜV at a waste incineration

source in accordance with the 17th BImSchV in the 0 to 20 mg/dscm measuring range. The

instrument response must be correlated by comparison to manual gravimetric data. The

manufacturer asserts that water droplets are widely ignored by the instrument, due to the specially

selected laser wavelength. 

4.10 MONITOR LABS 300L IN-SITU LIGHT SCATTER

The 300L uses the principle of backward light scattering in the red light spectrum. An

electronic modulated laser emitting diode provides the light source. The laser light is directed into

the stack at a slight angle, so that, for stacks larger than about 6 feet, a light trap is not needed. 

This instrument’s measuring range is 0 to 20 mg/acm up to 20,000 mg/acm. Manual zero and

upscale drift checks can be done to meet daily QC check requirements. 

The footprint of the 300L is a single optical head assembly attached to a special port

flange (provided by the vendor) with dimensions of approximately 15 inches long by 8 inches high

by 36 inches wide and weighing about 34 pounds. A single, 3.5 to 6-inch port with the special

flange is needed for installation of this instrument onto the stack. A purge air system (about 17 

inches wide by 8 inches deep by 37 inches high and weighing about 71 pounds) is needed to keep

the optical surface clean. The electrical power requirement is 120V. 

The instrument response must be correlated in mg/acm by comparison to manual

gravimetric data. The 300L will measure condensed water droplets in the gas stream as

particulate.

4.11 BHA GROUP CPM 5000 SCINTILLATION

The CPM 5000 uses the principle of scintillation or modulation in the intensity of the

transmitted light beam. The receiver senses the light signal modulation and converts it to PM

concentration (i.e., signal modulation is proportional to PM concentration). The transmitter and

receiver are located on opposite sides of the duct; therefore, this instrument measures across stack

PM concentration. As the PM concentration increases, the amplitude of the signal modulation

increases, and the instrument response can be correlated in mg/acm by comparison to manual
4-10

gravimetric data. Because the CPM 5000 measures signal variations resulting from moving

particles rather than from a diminished intensity of the incident light beam, the instrument is

relatively unaffected by particulate accumulation on the optics windows, optical misalignment, or

aging of the transmitter and receiver. The CPM 5000 has zero and upscale drift check capabilities

for daily QC checks. 

The footprint of the CPM 5000 is a box containing the microprocessor controls with

dimensions of approximately 24 inches square and 6 inches deep. The transmitting and receiving

optical heads are small and are attached to 2.5-inch port flanges on opposite sides of the stack. 

The microprocessor control box weighs about 30 pounds and the optical heads each weigh about

3 pounds. Two 2.5-inch ports are needed for installation of this instrument onto the stack. The

electrical power requirement is 110V. 

This instrument was tested as part of the short-term field test done by EPRI at a coal-fired

boiler, and it is also being evaluated in a second EPRI field test. The CPM 5000 was approved by

the German TÜV to meet the requirements for accuracy and repeatability for power plant

applications. The CPM 5000 will measure condensed water droplets in the gas stream as

particulate.

4.12 PCME SCINTILLA SC600 SCINTILLATION

The Scintilla SC600 uses optical scintillation technology coupled with advanced design

techniques to monitor PM concentration. The SC600 can measure PM concentration as low as

2.5 mg/acm per meter of path length. The scintillation technology and advanced techniques

reduce zero and upscale drift. The instrument uses modulated light to eliminate effects of stray or

ambient light. The transmitter and receiver are located on opposite sides of the duct; therefore,

this instrument also measures across-stack PM concentration. The instrument response increases

with PM concentration and can be correlated in mg/acm by comparison to manual gravimetric

data. The SC600 has zero and upscale drift check capabilities for daily QC checks.

The footprint of the SC600 is a small control module with dimensions of approximately

10 inches wide by 7 inches high by 4 inches deep. The transmitting and receiving optical heads

are small and are attached to 2-inch port flanges on opposite sides of the stack. The control

module weighs about 8 pounds and the optical heads each weigh about 12 pounds. Two 2-inch
4-11

ports are needed for installation of this instrument onto the stack. The electrical power

requirement is 110V. 

This instrument was tested as part of the short-term field test done by the EPRI at a coalfired boiler, and it is also part of a second EPRI field evaluation at another coal-fired boiler. The

SC600 has MCERTS approval meeting the accuracy and repeatability requirements for power

plant applications. The SC600 will measure condensed water droplets in the gas stream as

particulate.

4.13 INSITEC TESS IN-SITU OR EXTRACTIVE LASER LIGHT EXTINCTION-SCATTER

The Insitec TESS provides real-time PM concentration data for particles ranging in size

from 0 to 20 microns. The TESS can measure PM concentrations in-situ with an up to

8-foot-long probe or in a sample extracted from the stack. The in-situ TESS has been evaluated

in both laboratory and field studies by the Department of Energy (DOE), Southern Research

Institute, and the EPA (Giel et al., 1995). The in-situ TESS is capable of measuring PM

concentration as low as 1.3 mg/acm. A prototype of the extractive TESS was demonstrated in a

short-term field test done by EPRI at a coal-fired boiler. The manufacturer indicates the

instrument is insensitive to particle variations (particle size distribution) and to process changes

(particle composition). 

4.14 PCME DUSTALERT 90 ELECTROSTATIC INDUCTION

The DustAlert 90 uses a patented electrostatic induction measurement principle; where

particles in the gas stream interact with a probe inserted in the duct and induce charge movement

in the probe. The AC current generated by charge induction in the probe can be directly related

to the PM concentration. This instrument filters out the DC current generated by the

particulate/probe interaction. The manufacturer asserts that the DustAlert 90 can measure PM

concentration as low as 0.02 mg/acm. Unlike triboelectric technology, the particles do not need

to collide with the probe to be detected. The instrument’s output can be correlated to mg/acm

from manual gravimetric data. However, it is more often used to display and record in a relative

“Emission Factor” scale, which indicates emissions as a multiple of “reference” emissions (i.e., as

a baghouse bag leak detection device). The DustAlert 90’s correlation to PM concentration is

affected by changes in particle size distribution, particle type, and particle charge, thus eliminating

applications on wet exhaust gas stacks and sources controlled by electrostatic precipitators. 
4-12

The footprint of the DustAlert 90 is a small module with dimensions of approximately

10 inches wide by 7 inches high by 4 inches deep. The module extends about 6.5 inches back

from the port. A 7/8-inch diameter sensor probe extends into the stack and is attached by a

1.5-inch NPT port. The electrical power requirement is 110V. 

This instrument has been type certified by the Environment Agency under the MCERTS

program in the United Kingdom. Also, TÜV notes that this instrument should only be used in

constant velocity and constant gas composition environments; however, the velocity restriction

does not apply to the DustAlert 60 model. 

4.15 AUBURN INTERNATIONAL TRIBOGUARD III OR II IN-SITU TRIBOELECTRIC

The Triboguard II and III use proven triboelectric technology, invented nearly 25 years

ago. These instruments are low maintenance and can detect baseline PM concentrations as low as

0.005 mg/acm (as established by the manufacturer). The Triboguard instruments are primarily

used for baghouse broken bag detection (Fabric Filter Bag Leak Detection Guidance, 1997). 

Since triboelectric type instruments are sensitive to changes in stack gas velocity, particle size,

and particle characteristics (e.g., charge and composition), the Triboguard instruments are not

commercially marketed as potential PM CEMS; however, they are used in some applications in

the United Kingdom. This instrument is roughly the same size as the DustAlert 90.

4.16 CODEL STAKGARD TRIBOELECTRIC DUST MONITOR

The StakGard uses triboelectric technology (i.e., the AC current generated by particles

flowing around the probe) to detect PM concentration. The AC current generated by charge

induction in the probe can be directly related to the PM concentration. This instrument filters out

the DC current generated by the particulate/probe interaction. The manufacturer asserts that the

StakGard can measure PM concentration as low as 0.1 mg/acm. The instrument’s output can be

correlated to mg/acm from manual gravimetric data; however, it is more often used as a baghouse

bag leak detection device. The StakGard’s correlation to PM concentration is affected by

changes in particle size distribution, particle type, and particle charge; however, Codel has

designed a metal mesh housing around the probe to reduce the effect of particle charge after an

ESP. This instrument has been type certified by the Environment Agency under the MCERTS

program in the United Kingdom. This instrument is also roughly the same size as the

DustAlert 90.
4-13

4.17 OPACITY/TRANSMISSOMETERS

For completeness, and because some opacity monitors have been type certified as

particulate CEMSs, opacity monitors have been included in this section on known PM CEMSs. 

Although each opacity monitor is not presented separately as the other PM CEMS presentations

above, Table 4-1 includes a comparison on many opacity monitors that could be applicable as a

PM CEMS in specific applications.
4-14

TABLE 4-1. COMPARISON OF OPACITY MONITORS AS PM CEMSs

Land

Combustion

4500 mkII

Durag

DR-280

Durag

DR-290

KVB-Enertec

MIP

Monitor Labs -

USI

560 LightHawk

Rosemount

OPM 2000R

Sick

OMD 41

Phoenix

Instruments

OPAC 20/20

Dual Pass Yes Yes Yes No Yes Yes Yes Yes

Light Source LED - Green Tungstun Lamp

- White

Wide Band

Diode-White

Helium-Neon

Laser - Green

LED - Green Frosted,

incandescent

lamp - White

LED - Yellow LED - Green

Electrical/

Mechanical

Modulation

Electrical

3k Hz

Mechanical

1.2k Hz

Electrical 

2kHz

Electrical Electrical

2.4k Hz

Liquid crystal

windows

(electrical)

Electrical Electrical

2.5k Hz

PM

Measurement

Concentration

As low as

1.5 mg/acm

(1 μm dust)

From 0-0.1 to

0-1.6 extinction

1 mg/acm

resolution for

1 μm dust and

10-foot path

length

For 1 μm dust

and 20-foot

path length - 

single-digit

mg/acm

From 0 to 3

extinction

From 0-0.1 to

0-2 extinction;

PM

concentration

as low as

1.2 mg/acm

From 0-0.1 to

0-2 extinction

Footprint 30" long x

18" wide x

24" high

including purge

system and

shutters

Transceiver

7" wide x

9" high x

22" deep

Retroreflector

7" x 9" x 13"

Transceiver

7" wide x

13" high x

16" deep

Retroreflector

7" x 10" x

11"

Transmitter

12" wide x

18" high x

6" deep

Receiver 5" x

5" x 8"

without

purge system

22" long x

20" wide x

33" high

including purge

system and

weather cover

34" long x

13" wide x

29" high

including purge

system

Transceiver

15" x 8" x

11"

Reflector 11" x

8" x 11"

without

purge system

and

protective

cover

Both sides

22" wide x

30" high

Transceiver

27" long

Retroreflector

18" long

Includes

weather cover

and air purge

system with

shutters
4-15

TABLE 4-1. (CONTINUED)

Land

Combustion

4500 mkII

Durag

DR-280

Durag

DR-290

KVB-Enertec

MIP

Monitor Labs -

USI

560 LightHawk

Rosemount

OPM 2000R

Sick

OMD 41

Phoenix

Instruments

OPAC 20/20

Weight 60 lb per side Transceiver

35 lb

Retroreflector

13 lb

Purge air

blowers 65 lb

each

Transceiver

22 lb

Retroflector

15 lb

Purge air with

weather hood

65 lb each

side

Transceiver

27 lb

Retroreflector

7 lb

Purge air

blower 22 lb

Weather cover

and mounting

plate 43 lb

Transceiver

80 lb

Retroreflector

40 lb

Transceiver

27 lb

Retroreflector

18 lb

Transceiver

26 lb

Retroreflector

9 lb

Weather

enclosure and

air purge

system

125 lb/side

Electrical

Power

Requirement

110 V 115 V

220 V for

blowers

90-264 V

48-62 Hz

110 V

110 V for

blowers

115 V

220 V for

blowers

110-240 V 90 ... 267 V

120 V/3 or

230 V/3 for

purge air

system

115 V or 220 V

Type Approval German TÜV -

1997

German TÜV -

1978

German TÜV -

2000 expected

German TÜV -

1995
5-1

5.0 SUMMARY OF PM CEMS DEMONSTRATION FIELD STUDIES

Many field studies demonstrating the performance of PM CEMSs have been conducted. 

TÜV conducted most of the early evaluations and type certifications of PM CEMSs. Later, as the

EPA considered their use, the EPA performed several field evaluations of PM CEMSs. Also, at

least two industry groups have done field evaluations of PM CEMSs. This section presents a

summary of those field studies.

5.1 TÜV CERTIFICATION TESTING OF PM CEMS

In Germany, all CEMSs, including PM CEMSs, are type certified and approved for use at

a particular industry type. A PM CEMS cannot be used on a source in Germany unless it has

been certified. TÜV is the principle agency that conducts CEMS certifications in Germany.

5.1.1 Sigrist CTNR

The Sigrist CTNR, a light scattering type PM CEMS, was evaluated by TÜV Rheinland in

the laboratory and in the field (Report on the Suitability Testing . . . CTNR, 1997). The

laboratory test checked the following using two identical instruments:

• All instrument functions,

• Instrument characteristics (linearity and common response),

• Stability of the zero and reference filter values,

• Effect of variations in supply line voltage,

• Effect of relative humidity, rain, vibrations, and operating position, and

• Proper operation of the self-monitoring feature.

The field test was done using the same two instruments from the laboratory test at a refuse

incinerator from April 16, 1997 to June 4, 1997 and at a coal-fired furnace from June 12, 1997 to

August 12, 1997. The field test evaluated the following:

• Dead time and setting time,

• Detection limit,

• Correlation capability,

• Reproducibility,

• Stability of instrument characteristics,

• Maintenance interval,
5-2

• Data availability, and

• Functional test and correlation.

The results of TÜV’s evaluation of the Sigrist CTNR PM CEMS indicate that it met all of

the applicable requirements with the exception that it does not have the capability of doing

automatic zero and upscale calibration checks. However, TÜV recommended the CTNR for

monitoring PM emissions from incinerators and power plants, noting the reservation about the

lack of an automatic calibration feature.

5.1.2 Durag F-904

The Durag F-904, a beta gauge type PM CEMS, was evaluated by TÜV Rheinland in the

laboratory and in the field (Performance Testing of the F-904 Beta Gauge). The laboratory test

checked the following:

• Effect of variations in supply line voltage, and

• Effect of changes in ambient temperature on (1) the zero and span signals, (2) the total

volumetric flow sampled during the measuring cycle, and (3) the dilution air volume.

The field test was done on two identical instruments at a municipal waste combustor from

July 31, 1989 to December 31, 1989. The instruments were installed downstream of an ESP and

wet scrubber and operated in the following stack gas conditions:

• Stack diameter 78.7 inches

• Average stack gas velocity 45.9 feet per second

• Dew point of stack gas 149EF

• Stack gas temperature 154.4EF

• PM concentration < 10 mg/acm

The TÜV report notes that the F-904 was tested under recognizably difficult operating

conditions. The field test evaluated the following monitor features:

• Correlation capability,

• Reproducibility,

• Maintenance interval, and

• Data availability.

The results of TÜV’s evaluation of the Durag F-904 PM CEMS indicate that it met all of

the applicable requirements with the exception of the sample volume audit. On two of 13 tests,
5-3

the sample volume deviated from the expected volume by more than the allowable 8 percent. 

However, this test was done at a dilution ratio of 4 to 1, and TÜV determined that the monitor

could fully meet the sample volume accuracy requirement at a dilution ratio of 2 to 1.

5.1.3 Durag DR-300-40

The Durag DR-300-40, a light scatter type PM CEMS, was evaluated by TÜV Rheinland

in the laboratory and in the field (Report on the Performance Testing of the D-R 300-40 Dust

Concentration Monitor, 1992). The laboratory test checked the following:

• Calibration capability in a test duct, where the effect of changes in particulate size was

evaluated,

• Effect of variations in supply line voltage,

• Effect of changes in ambient temperature,

• Testing of the dirty window correction,

• Linearity check, and

• Effect of ambient light.

The field test was done on two identical instruments at a secondary lead smelter kiln from

February 27, 1992 to June 3, 1992. The instruments were installed downstream of a baghouse

and operated in the following stack gas conditions:

• Stack diameter 41 inches

• Stack gas velocity 30 to 59 feet per second

• Dew point of stack gas 50 to 122EF

• Stack gas temperature 140 to 230EF

The field test evaluated the following monitor features:

• Correlation capability and effect of process changes on the correlation stability,

• Reproducibility,

• Maintenance interval ,

• Data availability, and

• Necessity of a light trap.

The results of TÜV’s evaluation of the Durag DR-300-40 PM CEMS indicate that it met

all of the applicable requirements with the following notes:
5-4

• For installations on thick or double-walled stacks, the scattering volume must be within

the flowing stack gas.

• Since the scattering volume is only 3 to 11 inches from the instrument face, for

installations on stacks greater than 6.5 feet in diameter, the monitor must be shown to

provide a representative sample.

• A light trap may be omitted if the interference from reflected light is demonstrated to be

less than 2 percent of the measuring range.

5.2 EPA/OSW FIELD DEMONSTRATION – HAZARDOUS WASTE INCINERATORS

The OSW wanted to propose PM CEMSs as part of their Hazardous Waste Combustion

MACT rule. Before proposing PM CEMSs, OSW did two preliminary field studies and a

comprehensive field evaluation. 

5.2.1 Mixed Solid and Liquid Hazardous Waste Incinerator

The first preliminary test examined three PM CEMSs at a mixed solid and liquid

hazardous waste incinerator located in Bridgeport, New Jersey. The three PM CEMSs were

chosen to represent three different measurement techniques: light scattering, time-dependent

optical attenuation, and beta attenuation. The CEMSs were installed downstream of a pilot scale

wet electrostatic precipitator (ESP). The focus of this test was to determine the PM CEMS’s

viability at a wet ESP installation. 

The test was conducted in three phases during March of 1995. First, the PM CEMSs

were calibrated according to ISO 10155 using EPA Method 5. Three paired Method 5 tests were

done at each of three operating conditions designed to produce different PM loadings. The PM

concentrations ranged from a low of about 1 mg/m3 to a high of about 30 mg/m3. Second, the

CEMSs were operated for 2 weeks. Finally, another set of Method 5 tests were done to check

the stability of the original calibration. The final Method 5 testing consisted of four paired test

runs at only two operating conditions. PM concentrations were less than 1 mg/m3 during all four

test runs (i.e., the change in operating conditions did not change the PM concentration).

The PM CEMSs evaluated were the following:

• Sick Inc. RM200,

• BHA Group CPM1000TM, and

• Environment S.A. Beta M5.
5-5

The Sick RM200 and BHA CPM1000 were operating for the initial Method 5 tests,

during the 2-week experimental period, and the final Method 5 tests. The Beta M5 was not

operating during the initial Method 5 tests but operated during the experimental period and final

Method 5 tests.

The OSW reported the following conclusions from this brief test:

• The calibration data did not meet ISO 10155 requirements for (1) three or more different

PM concentration levels and (2) nine or more data points.

• With proper care, an optical device used in conjunction with a heated bypass can be

calibrated in a wet exhaust stream.

• For a low-temperature, saturated stack gas stream, extracting and drying a slipstream is

more appropriate than attempting to make in-situ optical measurements. The CPM1000

responded to liquid droplets in the exhaust stream.

• Not enough data were obtained to properly evaluate the performance of the Beta M5.

• The PM CEMSs responded to changes in PM concentration levels.

More information on this test can be found in the document entitled “Draft Technical

Support Document for HWC MACT Standards, Volume IV: Compliance with the Proposed

MACT Standards,” February 1996, Pages 4-2 to 4-9.

5.2.2 Hazardous Waste Burning Cement Kiln

The OSW chose a hazardous waste cement kiln in Fredonia, Kansas for another evaluation

of PM CEMSs and a test of the initial draft PM CEMS performance specification (PS-11) criteria. 

The facility manufactures cement from raw materials in a two-phase wet process kiln. Particulate

emissions are controlled with an ESP. The PM CEMSs selected included two light-scattering

monitors: the ESC P5A and the Sick RM200. The tests involved triplicate testing at three

different ESP power settings ranging from 55 to 140 KW; each Method 5 test run had paired

trains. Initial Method 5 correlation tests were done in May and June 1995. A final test was done

in July 1995 and served as a simulated response correlation audit (RCA). The test contractor had

extreme difficulty obtaining consistent results between the paired Method 5 trains. A concerted

effort was made to achieve an appropriate test matrix and distribution over three PM levels for

each calibration test. During each test period, data from one of the Method 5 trains was

disregarded as suspect. 
5-6

The OSW reported the following conclusions from this brief test:

• The correlation is highly sensitive to errors that can occur in making the manual method

measurements.

• The ESC P5A correlation test produced encouraging but inadequate results in terms of

meeting the draft PS-11 criteria. Also, the P5A’s RCA test results did not meet the

performance criteria.

• The Sick RM200 experienced some operational problems attributed to the heated, purgeair system. The instrument was removed during the initial correlation test program. When

the instrument was reinstalled, the response continued to deteriorate. 

More information on these tests can be found in the document entitled “DRAFT

Particulate Matter CEMS Demonstration, Volume I: DuPont, Inc. Experimental Station On-site

Incinerator,” Wilmington, DE, December 1997, Pages 2-42 to 2-44.

5.2.3 DuPont Hazardous Waste Incinerator

The preliminary tests presented above encouraged OSW to conduct a long term (6 months

to 9 months) demonstration to determine what PM CEMS performance could be achieved at a

reasonable worst-case source. Because the work would be used to support a proposed

requirement that a PM CEMS be used on a hazardous waste combustion device, OSW chose the

DuPont Experimental Station’s hazardous waste incinerator for this demonstration. Among such

sources, a source like DuPont’s would cause the particulate matter in the stack to be more

variable, thus causing a more variable response from the PM CEMS than at other sources under

consideration (e.g., cement kilns and light-weight aggregate kilns). The EPA also obtained

information to characterize PM CEMS installation needs, data availability, maintenance and

personnel requirements, and costs. One particularly important piece of information learned from

this test was that the PM CEMS can be sensitive to emissions variability on a real-time basis. 

Neither periodic short-term manual testing nor operational parametric monitoring would provide

an adequate picture of this variability for standard setting purposes. Only PM CEMS data

collected over a relatively long period of time would provide data sufficient for the statistical

analyses necessary for establishing achievable continuous compliance emissions limits. 
5-7

In addition to the importance of long term data gathering in setting standards, the EPA

also learned from this test the importance of precise manual particulate matter measurements. 

The variability associated with manual method imprecision can mask the true performance of the

PM CEMS. In response to this issue and to improve sample recovery and analysis time, the EPA

chose to redesign the Method 5 equipment when used at low particulate concentration sources. 

These changes became EPA’s Method 5i. To evaluate method precision, the EPA used dual

Method 5i trains (two Method 5i trains conducted simultaneously from different ports) and

established acceptable paired train precision criteria. 

The EPA also learned much about PM CEMS performance characteristics. This

information included the need to address the performance characteristics of different technologies,

the need to use data flags as indicators of potential problems, the importance of instrument set-up

and a “debugging period.” This knowledge led to changes in the draft performance specification

criteria and associated QA/QC requirements.

The DuPont tests extended over a 9-month period, from September 1996 to May 1997. 

Tests conducted from September to November, 1996 were an extension of the learning

experience started in the EPA’s preliminary test program. Data collected from September to

November 1996 were not considered in the final analysis of results. Forty-four Method 5i paired

train tests were conducted from December 1996 through May 1997. The EPA conducted the

initial correlation testing in 1-week periods each month from December 1996 through

March 1997. A second correlation was done in April 1997. Finally, the 9-month demonstration

program ended with a RCA in May 1997.

In summary, these tests led the EPA to believe that PM CEMS are a viable accurate

measure of real-time particulate matter emissions. The EPA believes the approach to correlating

emissions to gravimetric manual methods can result in an adequate correlation. The EPA also

believes that data availability, maintenance and personnel, and overall costs associated with

particulate matter CEMSs are representative of other CEMSs, such as SO2 analyzers for utility

boilers. However, site decisions, such as the technology employed for a given application, the

QA/QC capabilities of the CEMS, and the accuracy of the manual method data collected, can

affect the viability of a given PM CEMS at a particular source. More information on the DuPont
5-8

tests can be found in the Particulate Matter CEMS Demonstration final report at the EPA Office

of Solid Waste’s Web site: http://www.epa.gov/epaoswer/hazwaste/combust/CEMS. 

5.3 ELECTRIC POWER RESEARCH INSTITUTE – COAL-FIRED BOILER WITH ESP

Another field test program was sponsored by EPRI and conducted at Georgia Power

Company’s Plant Yates. Yates Unit 7 uses a conventional Combustion Engineering tangentially

fired boiler with a rated generating capacity of 360 MWe. The unit burns eastern bituminous coal

and is equipped with low NOx burners and separate overfire air. The particulate emission limit

for Unit 7 is 0.24 lb/mmBtu, and particulate emissions are controlled by an ESP. This program

was designed to provide data for use in a rigorous evaluation of both ESP performance models

and PM CEMS. 

The following five devices were tested:

• BHA CPM 5000,

• PCME SC600,

• Insitec extractive TESS,

• Spectrum Systems (via Sabata), and

• Lear Seigler RM41 opacity monitor.

Of the four instruments classified as a PM CEMS, only the BHA CPM 5000 and PCME SC600

were commercially available at the time of the EPRI test, and only the BHA CPM 5000 had been

used on other field evaluations. The PCME SC600 has since received MCERTS approval. The

Insitec extractive TESS and Spectrum System devices were prototypes.

The test plan was to evaluate three different ESP power conditions, which would result in

three different particulate mass emission levels, during three separate weeks of testing, for a total

of nine independent test conditions. Testing was done in June and September 1998. During each

week, 15 paired Method 17 test runs were conducted. The first 2 weeks of testing were

performed during consecutive weeks and the third week of testing was approximately 3 months

later. The fundamental premise of this field evaluation was to use the initial week of testing to

develop correlation equations for the PM CEMSs. The second week of testing, conducted

immediately following the initial week, provided information regarding the short-term accuracy

and stability of the PM CEMSs. The third week of testing, conducted approximately 3 months

following the initial 2 weeks, provided information regarding the long-term accuracy and stability
5-9

of the correlations. Unfortunately, during the 3-month period between the week 2 and week 3

tests, the four PM CEMSs were not properly maintained.

PM concentrations were varied by (1) deenergizing ESP fields (i.e., simulating the

complete loss of ESP sections, the most common failure mode of an ESP) and (2) turning down

power on all ESP sections in increments (i.e., simulating problems attributable to high-resistivity

ash or close clearance). PM concentrations during the 3 weeks of testing are presented in

Table 5-1.

TABLE 5-1. PM CONCENTRATIONS FOR THE THREE WEEKS OF 

THE EPRI PM CEMS TEST

PM concentrations Week 1 Week 2 Week 3

Low ~ 0.002 lb/106 Btu,

1.8 mg/m3 and

3 percent opacity

~ 0.012 lb/106 Btu,

9.1 mg/m3 and

6.7 percent opacity

~ 0.019 lb/106 Btu,

15.3 mg/m3 and

7.4 percent opacity

Mid ~ 0.06 lb/106 Btu,

49.5 mg/m3 and

15 percent opacity

~ 0.057 lb/106 Btu,

42.3 mg/m3 and

16.0 percent opacity

~ 0.121 lb/106 Btu,

94.5 mg/m3 and

18.3 percent opacity

High ~ 0.23 lb/106 Btu,

174 mg/m3 and

25 percent opacity

~ 0.121 lb/106 Btu,

87.5 mg/m3 and

21.5 percent opacity

~ 0.149 lb/106 Btu,

119 mg/m3 and

19.2 percent opacity

The high-PM-concentration condition during week 1 produced a significant number of “chunky”

carbon particles; therefore, this condition was not repeated in the other test periods. 

The conclusions from this EPRI study were the following (Roberson et al., 1999):

• The paired Method 17 sampling trains showed very good measurement precision and a

tolerance interval of 12 mg/m3 at an emission limit value of 75 mg/m3 (~ 0.10 lb/mmBtu).

• The BHA CPM 5000, PCME SC600, and prototype Insitec extractive TESS passed the

draft PS-11 correlation criteria. The prototype Spectrum and opacity monitor had

confidence intervals and tolerance intervals well outside the draft PS-11 requirements. 

The PM CEMSs correlation statistics from the week 1 test are presented in Table 5-2. 

• The week 3 tests that were used for the RCA, showed that none of the three PM CEMS

that passed the initial correlation met the RCA criteria. 
5-10

• The ESP inlet particle size distribution ranged from 21.5 to 24.4 microns for the first two

weeks of testing and was 30.9 during the third week. EPRI believes the skewed particle

size distribution and geometric standard deviation is due to either the retrofit of low-NOx

burners in a short furnace or the wearing of the coal pulverizes.

TABLE 5-2. PM CEMSs CORRELATION STATISTICS FOR 

THE EPRI PM CEMS TEST

Instrument Correlation Coefficient Confidence Interval Tolerance Interval

BHA CPM 5000 0.986 6.7 % 18.2 %

PCME SC600 0.984 6.9 % 19.2 %

Insitec extractive

TESS

0.991 9.4 % 19.2 %

Spectrum Systems

(via Sabata)

0.939 21.1 % 45.5 %

Lear Seigler RM41

opacity monitor

0.937 13.6 % 41.1 %

More detailed information on the EPRI test at Plant Yates can be found in a paper written

for the EPRI CEM Users Group Meeting at the following RMB Consulting Web site:

http://www.rmb-consulting.com/cinnati/rlrpaper.htm

5.4 ELI LILLY – HAZARDOUS WASTE INCINERATOR

Eli Lilly and Company (Eli Lilly), the Chemical Manufacturers Association (CMA), and

the Coalition for Responsible Waste Incineration (CRWI) jointly sponsored a two-phase test

program of PM CEMSs. The summary presented below was taken from a draft report provided

by Eli Lilly. This test was done at a liquid hazardous waste incinerator at the Eli Lilly Clinton Lab

in Clinton, Indiana. The instruments assessed in this study were an Environment S.A. (ESA)

Model Beta 5M and a Sigrist Photometer AG (Sigrist) Model KTNRM/SIGAR4000.

Phase one of the program demonstrated that the instruments, as initially configured, would

not meet the requirements of draft PS-11. During the same period as Phase One, Eli Lilly

purchased and installed two Sigrist monitors at a facility in Ireland. Eli Lilly contracted TÜV

Rheinland to calibrate the instruments which led to new knowledge on the calibration of PM CEM
5-11

instruments. Eli Lilly conducted Phase Two testing using knowledge gained from the Phase One

testing, the DuPont testing, and the TÜV Rheinland calibration in Ireland.

5.4.1 Phase One

Phase One of the Eli Lilly evaluation was designed to duplicate the testing conducted at

the DuPont Hazardous Waste Incinerator, but on a source that was saturated with water vapor. 

The evaluation was conducted over a 5-month period from February to June 1998. During this

period, a total of 74 paired Reference Method 5i (M5i) sample runs were completed at varying

particulate levels from 17 to 45 mg/dscm at 7 percent O2. Of the 74 test runs, 70 test runs

produced acceptable paired M5i results.

The Reference Method data was compared to the output of the two instruments and the

requirements of draft PS-11 with the following conclusions:

• None of the data sets met the draft PS-11 criteria for correlation coefficient but most

passed the CI and TI criteria.

• The Sigrist had a significantly higher correlation coefficient than the ESA monitor did.

• The “best fit” correlation relation for the ESA was polynomial, versus little difference

between the linear and polynomial correlations relations for the Sigrist.

• Use of the polynomial correlation relation for the ESA would significantly limit the range

of the instrument.

• Evaluation of quarterly sets of the Sigrist data showed different slopes and correlation

coefficients.

The data availability of the instruments was 78 percent for the ESA and 96 percent for the

Sigrist. The ESA instrument, as designed and operated, had trouble dealing with the high

moisture level. Finally, both instrument’s measuring range was set too wide for the range of PM

concentrations.

In general, Lilly believes that the Phase One test was a learning experience, and the Phase

One results should not be used to judge the performance of these PM CEMSs.

5.4.2 Phase Two

Phase Two of the Eli Lilly program was designed using lessons learned from previous

testing. Phase Two incorporated new instrument operating procedures as well as design changes

to the ESA instrument. Eli Lilly noted the following changes were included:
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• The Sigrist instrument was limited to operate on a single range that spanned the known

particulate concentration (i.e., multi-ranging capability was eliminated because of nonlinearity between ranges).

• The ESA instrument had some design changes incorporated to make it operate better at

the high moisture levels.

• The sample period for the ESA instrument was changed from 6 to 15 minutes, changing

the sample collection time from 2.5 to 8.5 minutes.

During Phase Two (November to December 1998), 40 sets of paired train data were

collected using M5i with particulate concentrations ranging from 1 to 64 mg/dscm at 7 percent

O2. Of the 39 paired test runs (after one run, train 2 failed its leak check), four failed the

precision criteria. The paired train bias comparison had a correlation coefficient of 0.99 and a

slope of 0.97, indicating no bias.

The Method 5i test data was compared to the output of the two instruments and the

requirements of draft PS-11 with the following conclusions:

• Both instruments met the draft PS-11 correlation criteria. The correlation statistics are

presented in Table 5-3.

• Successful correlation required operating the incinerator at abnormal conditions to obtain

the needed range of PM concentration (i.e., the waste feed was stopped and only natural

gas was combusted to produce the low PM concentrations).

• During the Phase Two test, the incinerator was operated in excess of the proposed PM

standard for a hazardous waste combustor.

• Successful correlation required a substantial site-specific operational learning process with

the instruments (i.e., supporting the need for the shakedown period and correlation test

planning period in PS-11, see Sections 7.3 and 8.3 of this report).

Evaluation of the data collected shows that the best correlation relationship of the Sigrist

monitor was logarithmic with a correlation coefficient of 0.97. The ESA monitor was found to

have a linear relationship with a correlation coefficient of 0.99.
5-13

TABLE 5-3. PM CEMSs CORRELATION STATISTICS FOR 

THE LILLY PHASE TWO PM CEMSs TEST

Instrument Correlation coefficient Confidence interval Tolerance interval

ESA Beta 5M 0.99 2.6 % 9.1 %

Sigrist KTNR 0.97 6.7 % 24.3 %

Although both instruments met the correlation criteria, Eli Lilly had concerns because the

Sigrist was at the maximum tolerance level, 25 percent, of draft PS-11. Also, the ESA did not

track with the Sigrist 12.3 percent of the time. The trend analysis was based on an analysis of the

data using mA output of the monitor and the regression equation calculated using the data from

this test. During the periods in which the two instruments did not trend together, data from the

ESA were higher than the Sigrist. The difference was assumed to be in the ESA data because in

several instances the ESA had a sample volume error, but this error was not recorded. 

The data availability of the instruments for Phase Two were 98.1 percent for the Sigrist

and 85.8 percent for the ESA. The data for the periods that the ESA did not trend with the

Sigrist were treated as an instrument malfunction for the ESA.

5.5 EPA/OAQPS FIELD DEMONSTRATION – COAL-FIRED BOILER WITH BAGHOUSE

The EPA’s Office of Air Quality Planning and Standards (OAQPS) may require the use of

PM CEMSs in future standards. Also, States may require them for State Implementation Plan

(SIP) monitoring and Economic Incentive Program (EIP) monitoring. Additionally, industry

sources may use PM CEMSs for Title V monitoring. The EPA, therefore, desired additional

evaluations of PM CEMS technology on a long-term continuous basis. Also, the EPA wanted

additional data to support revisions to draft PS-11 and Procedure 2. The EPA initiated a

demonstration program to setup and operate PM CEMSs over an extended time to gather data for

assessing their performance against draft PS-11 and Procedure 2. The EPA chose a coal-fired

power plant that used a baghouse for particulate control for the test site.

The test site was Cogentrix of Rocky Mount Inc., located in Battleboro, North Carolina. 

This facility is an electric utility plant consisting of four identical boilers powering two electric

generating units. Each generating unit is rated at approximately 55-60 MWe for a total plant

electrical capacity of 115 MWe. Each of the generating units is powered by a pair of Combustion

Engineering stoker-grate power boilers. Each of the four boilers fires bituminous coal and is
5-14

rated for 375 mmBtu/hr heat input and steam output of 250,000 lb/hr. Each is equipped with a

Joy Technologies, Inc. dry type SO2 absorber (lime slurry scrubber) and a Joy Technologies

pulse-jet fabric filter (baghouse) for particulate control. The particulate emission limit for each

boiler is 0.02 lb/mmBtu.

The following three commercially available PM CEMSs (two light scattering types and

one beta gauge type) were included in the demonstration:

• ESC P5B,

• DURAG DR-300-40, and

• DURAG F904K.

The demonstration project proceeded as follows:

• The PM CEMSs were installed in early June 1999.

• A shakedown period lasted from June 12 through June 30, 1999.

• A 7-day drift test was done on each PM CEMS, an ACA was done on the two light

scatter type PM CEMSs, and a sample volume audit (SVA) was done on the beta gauge

type PM CEMS.

• A correlation test planning period consisting of nine preliminary Method 17 runs, which

were used for assessing the range of emissions (i.e., how to obtain three levels of PM

concentration) and setting the measurement range on the PM CEMS, was carried out over

the period of July 9-14, 1999.

• The initial correlation test consisting of 15 paired Method 17 runs was carried out during

the period of July 15-19, 1999.

• An RCA and ACA/SVA were done in late August 1999, about 1 month after the initial

correlation test.

• A second RCA and ACA/SVA were done in November 1999 to evaluate discrepancies

between the initial correlation and the first RCA.

• A final ACA/SVA was done on February 7, 2000 with project completion on February 16,

2000.

The duration of the demonstration project was approximately 8 months, with continuous

operation of the PM CEMSs and emissions data collection over the 6-month period following the
5-15

initial correlation test. All PM CEMSs were maintained in proper operating order during the

demonstration with daily zero and upscale drift evaluations.

PM concentrations were varied by adjusting a multi-position butterfly valve to bypass PM

from the inlet duct (dirty side) to the outlet duct (clean side) of the baghouse. The PM

concentrations during the initial correlation test and the RCAs are presented in Table 5-4.

TABLE 5-4. PM CONCENTRATIONS FOR THE EPA/OAQPS PM CEMS TESTa

PM concentrations Initial correlation First RCA Second RCA

Low ~ 4.5 mg/dscm and 3.7

 percent opacity

~ 3.6 mg/dscm and

5.1 percent opacity

No tests done at low

PM conc.

Mid ~ 16.4 mg/dscm and

4.1 percent opacity

~ 18.6 mg/dscm and

4.7 percent opacity

~ 22.5 mg/dscm and

9.3 percent opacity

High ~ 24.4 mg/dscm and

4.7 percent opacity

~ 38.6 mg/dscm and

5.5 percent opacity

~ 38.2 mg/dscm and

9.6 percent opacity

a Opacity readings were taken in the stack which discharges emissions from both boilers 2A and 2B.

Conclusions from this EPA/OAQPS demonstration were the following (Evaluation of

Particulate Matter Continuous Emission Monitoring Systems, 2000):

• The 37 paired Method 17 sampling trains during the initial correlation and the first RCA

showed very good measurement precision with an RSD of no greater than 4.3 percent. 

The bias between Trains A and B was only 2 percent for the initial correlation test and

2.3 percent for the first RCA. Except for one test run to demonstrate precision, paired

trains were not used during the second RCA.

• Three levels of PM concentrations could be obtained for a baghouse controlled unit by

using a baghouse bypass system that simulated a typical baghouse failure. When using a

particulate bypass system to increase the PM concentration, the point where the dirty gas

mixes with the clean gas must be well upstream of the manual reference method and the

PM CEMS measurement locations to avoid possible stratification of the PM. 

• All three PM CEMSs passed the draft PS-11 initial correlation criteria at an emission limit

of 17 mg/acm (used for the light scattering instruments) or 25.5 mg/dscm (used for the

beta gauge instrument) using a linear regression relation. The correlation statistics are
5-16

presented in Table 5-5. Note, the DR-300-40 had a confidence interval of 10.4 percent

compared to a criteria limit of 10 percent.

• All three PM CEMSs passed the initial QC checks for the 7-day drift, ACA, and SVA.

• All three PM CEMSs failed to meet the RCA criteria after 1 month of operation. Based

on results from the second RCA, a likely cause in the discrepance between the initial

correlation data and the first RCA data was a shift in the PM stratification at the PM

CEMS measurement location (which did not meet PS-11 siting criteria).

• Correlations generated using the combined initial correlation data and the RCA data failed

to meet the draft PS-11 criteria, and the correlations generated using only the RCA data

were just outside the draft PS-11 criteria bounds. During the second RCA, data collected

during 5 of the 6 test runs done at full boiler operating load fell within the tolerance

interval of the first RCA correlations.

• At reduced and variable boiler load conditions, the three PM CEMSs did not respond to

the higher PM concentrations as expected. 

• The two light scatter type PM CEMSs met the ACA criteria after 1 month, 4 months, and

6 months of operation.

• The beta gauge PM CEMS met the SVA criteria after 1 month, 4 months, and 6 months

of operation.

• Assuming that plant personnel could have responded to the observed maintenance issues

in a reasonable time, the light scatter PM CEMSs achieved 99 percent data availability and

the beta gauge PM CEMS achieved over 96 percent data availability.

TABLE 5-5. PM CEMSs CORRELATION STATISTICS FOR 

THE OAQPS PM CEMSs FIELD EVALUATION

Instrument Correlation coefficient Confidence interval Tolerance interval

ESC P5B 0.964 9.20 % 17.9 %

DURAG DR-300-40 0.955 10.4 % 20.2 %

DURAG F904K 0.988 5.37 % 10.7 %
6-1

6.0 FUTURE FIELD DEMONSTRATIONS

The EPA anticipates that additional field demonstrations of PM CEMSs will be done by

both the EPA and industry. To facilitate a successful field demonstration, this section presents

some guidelines that should be considered.

6.1 TEST PLAN GUIDELINES

A field demonstration or evaluation of PM CEMSs should be done in accordance with a

written test plan. In general, a written test plan should follow the outline provided in the

Emission Measurement Center’s 1991 Guidebook: “Preparation and Review of Site Specific Test

Plans.” The site specific test plan (SSTP) should contain the following information:

1. Introduction

• Summarize the test program and what criteria will be used to evaluate the PM

CEMS(s)

• Show a test program organization

2. Source Description

• Describe the process that is generating PM emissions

• Describe the control equipment

3. Test Program

• Describe the test objectives (e.g., demonstrate that a PM CEMS provides reliable and

accurate data for this source over an extended period, evaluate maintenance

requirements, determine if a PM CEMS satisfies PS-11 and Procedure 2 criteria)

• Show the test matrix, including personnel responsibilities (e.g., site modifications,

shakedown and planning periods, initial correlation test period, Procedure 2 audits,

instrument maintenance)

• Describe how the source and control equipment will be operated and how PM

concentrations at different levels will be obtained

4. Sampling Locations

• Include a diagram or photograph of the Reference Method sampling location

• Include a diagram or photograph of the PM CEMS measurement location,

5. Sampling and Analytical Procedures
6-2

• Describe the PM CEMS(s), including what instrument data will be logged (e.g., daily

calibration drift, operational flags, data averaging periods)

• Describe the Reference Method used, including dual/paired train arrangement, and

how on-site results will be obtained (as applicable)

• Present what process operating data will be collected to evaluate operation of the

source and control equipment

6. QA/QC Activities

• Present QC procedures that will be applied to the Reference Method sampling

• Present QC procedures that will be applied to the PM CEMS (e.g., daily calibration

drift checks, ACA, SVA) and who will do them

• Describe how the PM CEMS(s) measurement range will be properly set

• Conduct an independent check of the regression analysis

7. Safety Issues

6.2 MONITOR SELECTION GUIDELINES

When selecting a PM CEMS for a field demonstration project, the following should be

considered:

• What technology is to be demonstrated?

• Is that technology known to be affected by site specific conditions (see Section 8.2)? If

no, then the technology can be considered; if yes, then only consider the technology if

precautions are taken to offset the effect.

• Considering the measurement location, can the potential PM CEMS be installed (i.e.,

consider platform size and location versus the size of the instrument, stack/duct diameter,

weight limitations, installation efforts, exposure effects, the need for a light trap, etc.)?

• Select a PM CEMS that is commercially available. If a prototype PM CEMS is to be

evaluated, a second PM CEMS that uses the same technology and has been proven should

also be used.

• Only use a PM CEMS that does zero and upscale drift checks and one that has operational

fault indicators.

• Ensure the vendor can provide adequate support and assistance.
6-3

6.3 TEST PLAN APPROVAL AND DATA ANALYSIS

The final test plan should be completed at least 45 days before the initial correlation

testing is planned. For a field demonstration sponsored by the EPA, the industry group affected

should be given the opportunity to review the test plan. The industry group can provide

comments to the EPA. The industry group will also be invited to witness the initial correlation

testing and any other part of the program they desire. For a field demonstration sponsored by an

industry, the industry should submit the final test plan to the EPA and State agency for review at

least 45 days before the initial correlation testing. In reciprocation, the EPA and the State agency

should be invited to witness the initial correlation testing and any other part of the program they

desire.

Results of the field demonstration should be shared between the industry group and the

EPA. The industry group and the EPA are encouraged to separately analyze the data. Finally, a

consensus should be reached regarding the conclusions of the demonstration.
7-1

7.0 PM CEMS IMPLEMENTATION

Once PS-11 is finalized and published in the Federal Register, the EPA, State regulatory

agencies, and industry will be tasked with implementing PM CEMS programs. This section

provides guidance on the following topics: source applicability, how to select the appropriate PM

CEMS, how to conduct the initial correlation, what does the correlation mean and how accurate

are the data generated by the PM CEMS, what QA/QC measures to apply to PM CEMS, and

finally, issues to be addressed case by case. 

7.1 SOURCE APPLICABILITY

PM CEMSs have three main applications: (1) process monitoring, (2) compliance

assurance, and (3) compliance monitoring. As a process monitor, a PM CEMS can be used to

improve process performance by providing an indication that a setpoint has changed and an

adjustment is needed or to improve air pollution control device performance by indicating when

maintenance is needed. As a compliance assurance monitor, a PM CEMS can be used as an

indicator for reasonable assurance that an emission limit is not exceeded. A small amount of

testing would be needed to establish the not-to-exceed level, but a full correlation test can be

avoided. As a compliance monitor, the PM CEMS would provide a continuous record of actual

PM concentration. To be used as a compliance monitor, a full correlation test is needed. Specific

source applications of the PM CEMS in each of these areas are presented below.

The ESC P5B light scatter PM CEMS has been used as an ESP performance monitor at

many large electric utility plants in the U.S. (personal communication with Robert Nuspliger,

ESC). Furthermore, a PM CEMS has been used to monitor for product losses through an

exhaust stack during process changes (e.g., in the exhaust duct of a potato chip manufacturing

process to monitor for oil losses during process changes).

In Canada, many PM CEMSs are in use at pulp and paper mills with some being used as

environmental compliance assurance monitors in lieu of more frequent Reference Method testing

for compliance. In the United Kingdom, PM CEMSs are used at municipal waste combustors,

power plants, and cement kilns in a compliance assurance manner (personal site visits at two

facilities and personal communication with the U.K. Environment Agency, September 1999). 

Also, in Korea, PM CEMSs are used in a compliance assurance manner.
7-2

PM CEMS have been applied in Germany to industrial furnaces (i.e., coal- and oil-fired

units larger than 50 MW and gas-fired units greater than100 MW) following the requirements of

the 13th BlmSchV and to waste incinerators following the requirements of the 17th BlmSchV. In

Denmark, PM CEMSs are used at coal-fired power plants. In the United States, PM CEMSs

have been installed and evaluated on liquid hazardous waste burning sources, cement kilns,

copper smelters, a glass furnace, and oil- and coal-fired boilers.

When a PM CEMS is used for compliance monitoring, the PM emission limit that is used

as a compliance set point should be based on PM CEMS data collected from many representative

sources over an extended period (e.g., at least 6 months). The accuracy limitations of a PM

CEMS must also be considered when setting an emission limit. For example, in Germany the PM

CEMS’s confidence interval (e.g., 4 mg/dscm) is added to the baseline PM emission standard

(e.g., 30 mg/dscm) to determine the facility’s daily emission limit (e.g., 34 mg/dscm). Also, the

averaging period and whether the average is a block or rolling average are critical choices to be

made. These choices will have an effect on sources ability to remain in compliance (Joklik, 1999). 

Furthermore, the definition of particulate itself can be problematic at some sources, especially

when comparing in-situ PM CEMS measurements to extractive Reference Method measurements

(i.e., because of condensible particulate).

7.2 PM CEMS SELECTION

Since a PM CEMS determines PM concentration by measuring secondary properties of

the particulate, selecting the appropriate PM CEMS technology for the source is a critical first

step. Site-specific conditions must be considered (see Section 6.2 of this report). Also, different

types of PM CEMSs can report different PM concentrations for the same sample stream just

because of the concentration units (i.e., mg/dscm versus mg/acm) used in the correlation test. 

Some of the factors that affect PM concentration measurements made by the PM CEMSs

presented in Section 4 of this report are offered below (Joklik, 1999) along with some practical

suggestions.

• Opacity and light scattering monitors have responses that are functions of the particulate’s

index of refraction and size distribution. However, in addition to being more sensitive

than opacity monitors, light scatter monitors also provide more degrees of design freedom. 

Parameters such as light wavelength, scattering angle, and solid angle of detection affect
7-3

the response of the instrument, which makes it possible to minimize the influence of index

of refraction and size distribution over certain specified size ranges. However, since

optical techniques effectively measure particle volume, using them to infer PM

concentrations introduces an additional dependence on particle density. Since these

instruments respond to liquid droplets in the sample gas stream, in-situ devices of this type

are inappropriate for saturated or nearly saturated exhaust streams. Extractive devices of

this type that heat the sample gas may be used on saturated or nearly saturated exhaust

streams. Additionally, using these types of instruments on sample gas streams that are

likely to have varying particle size distributions is less desirable, unless precautions are

taken to avoid the effects of changing particle sizes (e.g., multiple correlation curves). 

These instruments are most appropriate for sources controlled by fabric filters (i.e.,

baghouse) or multi-stage air pollution control systems in which the particle size

distribution at the outlet of the device does not vary much.

• Beta gauge monitors have a weak dependence on particle composition. This effect arises

because of the composition dependence of the electron mass-attenuation coefficient (the

atomic number versus atomic mass ratio). The main issues associated with the use of a

beta gauge PM CEMS are practical ones: maintaining isokinetic sampling may be

necessary and sample loss may occur in the probe. The importance of these issues will be

site dependent. Since beta gauge type instruments are much less sensitive to changes in

particle size than optical based instruments, these instruments are more appropriate for

sample gas streams that are likely to have varying particle size distributions (e.g.,

following an ESP or sources that use many different fuels). Also, since beta gauge type

instruments extract and heat the sample gas, these instruments are appropriate for sample

gas streams that are saturated or nearly saturated. If a beta gauge instrument is used at a

source that varies its exhaust gas stream velocity a great deal (e.g., load following electric

power plant), the instrument must have the capability to adjust its sampling rate to

maintain isokinetic sampling.

• The response of probe electrification devices is a function of resistivity of the particles,

which depends on particle composition and humidity. The response is also affected by

flow velocity, particle size, and particle charge. Also, since a physical probe is inserted
7-4

into the sample gas stream, effects due to erosion and deposition must be considered. A

PM CEMS of this type should only be used in exhaust streams that do not have varying

particle sizes, do not have varying velocity, do not have saturated or near saturated

conditions, and do not have varying particle charge (e.g., cement kiln controlled by a

fabric filter). Probe electrification devices based on the AC portion of the current are not

as sensitive to gas velocity changes as DC measuring devices.

• The PM CEMS measurement location is critical, especially if the PM concentration will be

artificially increased for purposes of developing the correlation relation. The point where

high-PM-concentration gas is mixed with low-PM-concentration gas must be well

upstream of both the PM CEMS and the manual Reference Method measurement location. 

This is to ensure the particulate is evenly distributed and well mixed across the stack area

at the measurement location. Also, devices that can introduce dilution air or otherwise

disturb the air flow pattern must be well upstream of the PM CEMS measurement

location.

7.3 SITE-SPECIFIC CORRELATION TEST

Since a PM CEMS measures secondary properties of particulate (with the possible

exception of the beta gauge type monitors) and outputs a signal that is proportional to the PM

concentration, a PM CEMS must be correlated to the site specific conditions at the measurement

location. Also, a site-specific correlation will account for any PM stratification that may exist at

the PM CEMS measurement location. The procedure for carrying out a correlation test is

described in PS-11. Some specific issues related to the correlation test are presented in this

section. A correlation test consists of the following steps:

1. Install an appropriate PM CEMS at a representative location and start it according to

the manufacturer’s instructions.

2. Operate the PM CEMS and record the output for a Shakedown Period and then a

Correlation Test Planning Period (up to a 6-month period may be needed). Establish a proper

measurement range at the end of the Correlation Test Planning Period. The Shakedown Period

and Correlation Test Planning Period must not extend beyond the date when the PM CEMS must

be used to report emissions.
7-5

3. Carefully, conduct 15 paired train Reference Method tests for particulate while

simultaneously collecting PM CEMS output values over the range of PM CEMS responses

recorded during the Correlation Test Planning Period. Higher PM CEMS responses may be

tested to increase the effective range of the correlation equation by perturbing the air pollution

control system or other means.

4. Evaluate the Reference Method data for precision and bias, and calculate the

statistically appropriate correlation equation (linear or polynomial) from the valid, concurrent PM

CEMS responses and Reference Method PM concentrations.

5. For the selected correlation equation, compare the statistical parameters to the PS-11

criteria.

The main issues to resolve during the Shakedown Period and Correlation Test Planning

Period are the following:

• Plant people must learn how to properly operate the PM CEMS.

• The process should operate over its full operating envelope, especially in the areas that are

suspected to affect PM composition and concentration (e.g., all expected waste feeds, all

fuels, start-up and shutdown, sootblowing).

• The proper measuring range or sensitivity level must be set such that normal operations

are approximately 6 to 10 mA output but that concentrations at and just above the

emission limit do not exceed the upper measurement point (i.e., 20 mA). Also, the

measuring range must never be exceeded for a 15-minute average period. Completing this

task will likely require some Reference Method testing before the initial correlation test.

• The operating conditions that produce low and high PM concentrations must be

documented so that those conditions can be reproduced for the correlation test. If

changes in operation cannot produce a range of PM concentrations, some technique of

perturbing or bypassing the pollution control system can be used.

During the initial correlation test, the most critical task is to carefully and properly

perform the manual Reference Method tests and laboratory analysis. This task is critical because

the accuracy of the PM CEMS correlation can be no better than the accuracy of the Reference

Method measurements. The sole reason for requiring dual sampling trains is to help ensure the

accuracy of the Reference Method values by checking that the precision between the paired
7-6

Reference Method results is sufficiently high and that the bias between the two sampling systems

is sufficiently low. Although having a high level of precision between paired numbers does not

guarantee that either number is accurate, the chance that the number is accurate is greater than

with a single value. Another important point is to coordinate starting and stopping of the test

runs with the sampling interval of the PM CEMS. This point is most important for a batch type,

extractive PM CEMS (i.e., a beta gauge). Also, if port changes during the Reference Method

tests take a long time (e.g., 5 minutes or more), the PM CEMS data during port changes can be

discarded from the PM CEMS’s average output.

Since the paired Reference Method results must be evaluated for their precision before the

run can be considered valid, getting PM concentration results in the field is highly recommended. 

This requires sample recovery and laboratory analysis in the field. Furthermore, checking the

progress of the test program by plotting the Reference Method values against the PM CEMS’s

output during the correlation test is highly recommended.

Another requirement for a valid correlation test per draft PS-11 is to collect PM

concentrations over the full range of PM CEMS responses recorded during the Correlation Test

Planning Period. At most sources, some effort (e.g., operational changes or adjustments to the

pollution control system) will be needed to obtain the full range of PM concentration levels. 

Testing at PM concentrations above the emission limit is not required. Some examples of how a

source might obtain lower and higher PM concentrations are the following:

• For low PM concentrations:

• Burn only natural gas

• Stop product feed

• Shut off process and only run the fans

• Use filtered sample air

• For high PM concentrations:

• Change fuels combusted

• Change product or waste feed

• Perturb or bypass the pollution control system to simulate normal, unpreventable

upsets
7-7

The EPA is aware that some sources will not be able to create a wide range of PM

concentration levels for the correlation test. Therefore, draft PS-11 allows a source to perform

the correlation test over the range of PM concentrations normally experienced. The PM CEMS is

then limited to how far its response can be used for reporting PM emissions (i.e., 125 percent of

the highest PM CEMS response during the correlation test) before additional data must be

collected to extend the correlation. For example, if the PM CEMS responses ranged from 4.5 mA

to 5 mA during the correlation testing, the corresponding correlation equation from this data

could be used up to a PM CEMS response of 6.25 mA. When three hourly averages exceed

6.25 mA, additional test data at PM CEMS responses around 6.25 mA would have to be added to

the correlation data. This approach is particularly appealing when the limited range of PM

concentrations is much lower than the standard. This approach is used in Germany.

7.4 UNDERSTANDING THE MEANING OF THE CORRELATION

After a successful correlation test and development of the correlation relation equation,

one must understand the meaning and appropriate use of the regression equation (Joklik, 1999). 

The estimated regression equation that correlates the manual gravimetric PM concentration

measurements (e.g., mg/dscm) and PM CEMS measurements (e.g., mA) has associated with it a

degree of uncertainty expressed by two hyperbolae around the fitted line of the regression

equation (i.e., the mean of the estimated PM concentration values.) The first is a confidence

interval, defined in PS-11 as a 95 percent confidence level. The second is a tolerance interval,

defined in PS-11 as a 95 percent tolerance interval that contains at least 75 percent of the entire

population of PM concentration values. In other words, a tolerance interval will bracket at least a

certain proportion (e.g., 75 percent) of the population with a specified degree of confidence (e.g.,

95 percent). The width of the band determined by these bounds is narrowest at the point defined

by the mean of PM CEMS measurements and mean of PM concentration measurements. The

farther one moves away from the mean, the wider the bounds become. Thus, extrapolating the

estimated regression line and its confidence and/or tolerance bounds will necessarily result in

decreased precision in PM concentration measurements estimates. Therefore, the EPA’s policy

decision to limit the amount of extrapolation of a regression equation developed from data over a

narrow range of PM CEMS responses to 125 percent of the largest PM CEMS response is

supported by the statistical meaning of the correlation.
7-8

For a given PM concentration (i.e., mg/acm), several different PM CEMS responses (i.e.,

mA signal) can occur within the bounds of the tolerance interval (following along a horizontal line

from the upper tolerance interval to the lower tolerance interval, this is based on inverse

regression). Conversely, for a given PM CEMS output, several different PM concentrations can

occur (following along a vertical line from the lower tolerance interval to the upper tolerance

interval). Thus, the uncertainty in the PM concentration reported by a PM CEMS’s correlation

relation equation that meets PS-11 acceptance criteria is limited to ± 25 percent of the emission

limit value.

7.5 QUALITY ASSURANCE/QUALITY CONTROL

Quality assurance (QA) has two functions in the PM CEMS program:

1. Assessment of the continued quality of the PM CEMS’s data, and

2. Maintaining data quality by implementing quality control (QC) policies and corrective

action.

When the assessment function indicates a reduction in data quality, the QC procedures

must be revised until the PM CEMS produces data of acceptable quality. The specific QA/QC

activities found in Procedure 2 for a PM CEMS program are the following:

• Quality check of Reference Method data,

• Daily zero and upscale drift checks,

• Daily sample volume check (where applicable),

• Relative response audit (RRA),

• Response correlation audit (RCA),

• Absolute correlation audit (ACA), and

• Sample volume audit (SVA), where applicable.

As noted earlier, collecting quality manual Reference Method data is key to a successful

PM CEMS program. The quality of the Reference Method data applies to the initial correlation

test described earlier and to the RCA test. The quality of the Reference Method data is first

evaluated by the population relative standard deviation (RSD) between the paired Reference

Method data points from each individual test run. The RSD must meet the following criteria:
7-9

IF THEN

the average PM concentration > 10 mg/dscm RSD < 10 percent

the average PM concentration < 1 mg/dscm RSD < 25 percent

the average PM concentration is between 1 and

10 mg/dscm

RSD < the percentage determined from the

following equation: 

-(15/9) * mg/dscm + 26.667 

(i.e., the linear interpolation between

25 percent at 1 mg/dscm and 10 percent at

10 mg/dscm)

If the pair of Reference Method PM concentration values meets the RSD criteria, the data are

deemed acceptable. At the conclusion of the test program (either initial correlation or RCA), all

valid pairs are evaluated for systematic bias. The bias is evaluated by calculating the linear

regression of all valid pairs (Train B versus Train A), and comparing the slope from the linear

regression to the range of 0.93 to 1.07. If the slope is between 0.93 and 1.07, the bias is

acceptable, and the averages of each paired train are used in the initial correlation relation or

RCA.

On a daily basis, the PM CEMS is subjected to zero and upscale drift checks. This routine

check is done to assess system electronics and optics, light and radiation sources and detectors,

electric or electro-mechanical systems, and general stability of the system calibration. Basically,

the zero and upscale drift check is a daily health check of the instrument (i.e., is it still responding

to a reference value today as it did yesterday and the day before that, etc?). In general, the

instrument must be adjusted when the daily drift exceeds 4 percent, but it may be adjusted at

lower drift values. The instrument is considered out-of-control (i.e., the data are not valid for

compliance determination) when either the zero or upscale drift exceeds 4 percent for 5

consecutive days or exceeds 8 percent on any one day. 

For extractive type PM CEMS that measures the sample volume and uses the measured

sample volume as part of calculating the output value, a check of the sample volume measuring

equipment must be done on a daily basis. This sample volume check is done at the normal

sampling rate of the PM CEMS. The PM CEMS sample volume measurement must be adjusted

whenever the daily sample volume check exceeds 10 percent. The instrument is considered out-
7-10

of-control (i.e., the data are not valid for compliance determination) when the sample volume

check exceeds 10 percent for 5 consecutive days or exceeds 20 percent on any one day. 

At least once each calendar quarter (but no closer than 2 months), the PM CEMS must

have an ACA and a SVA (as applicable) done. The ACA applies to all types of PM CEMSs, and

the SVA applies to extractive type PM CEMSs that use the measured sample volume to calculate

PM concentration. An ACA and a SVA are higher level performance checks than the daily

checks. The ACA is designed to evaluate the performance of the PM CEMS across its full

measuring range by checking the instrument’s response at three audit points. If any of the ACA

audit points have an error in excess of ± 10 percent of the audit value, the instrument must be

repaired and a new audit done to confirm the proper operation of the instrument. The PM CEMS

manufacturer should provide the source with materials for the audit. A SVA is done by

measuring the instrument’s sample volume with a calibrated device (e.g., dry gas meter) and

comparing the audit value to the volume reported by the instrument. If the SVA shows an error

in excess of ± 5 percent of the audit value, the instrument must be repaired and a new SVA done

to confirm the proper operation of the instrument. Procedure 2 provides the method for

performing the SVA.

At the frequency specified in the regulation that requires the PM CEMS, at least 12 paired

manual Reference Method tests for the RCA must be conducted following the same procedures

described for the initial correlation test. Each paired train result must meet the same RSD criteria

as for the initial correlation. The RCA must include PM concentrations within the range obtained

during the initial correlation test. For the RCA, at least 9 of the 12 sets of PM CEMS/Reference

Method measurements must fall within the initial correlation’s tolerance interval bounds. If the

PM CEMS fails to meet this RCA criteria, the PM CEMS is out-of-control, and the following two

actions must be taken:

1. Combine the RCA data with the initial correlation data and perform the regression

analysis in PS-11 to develop a new correlation relationship. If this new correlation meets the

PS-11 criteria, the new correlation must be used, or

2. Do the PS-11 regression analysis on the new RCA data. If this new correlation

relation meets PS-11 criteria, it must be used.
7-11

Once every four calendar quarters, a RRA must be conducted. The RRA consists of

collecting three simultaneous Reference Method PM concentration measurements and PM CEMS

measurements at the as-found source operating conditions and PM concentration. Paired trains

for the Reference Method sampling are not required but are recommended to avoid failing the test

due to imprecise and inaccurate Reference Method results. For the RRA, at least 2 out of the 3

test runs must fall within the tolerance interval to ensure the PM CEMS correlation is still

applicable and accurate. EPA believes the RRA is a cost effective means to ensure that the PM

CEMS correlation remains applicable without the need to complete a costly RCA on an annual

basis. If the PM CEMS fails to meet this RRA criteria, the PM CEMS is out-of-control, and a full

RCA must be completed.

7.6 PS-11 ISSUES TO BE ADDRESSED CASE BY CASE

As discussed previously, the EPA produced a draft performance specification (PS-11) to

govern the installation and calibration of a PM CEMS. The EPA has been revising PS-11 based

on the results of its and industry’s field evaluations of PM CEMSs and comments received to the

proposed PS-11. Many issues have been resolved, but several issues need to be resolved on a

case by case basis. The PS-11 case by case issues are the following:

1. How to vary the source’s PM emission concentrations during the correlation test.

• How to simulate a normal, unpreventable, expected failure of the APCD?

• If adjusting the APCD changes the characteristics of the PM in the stack, some types

of PM CEMSs will not be applicable. 

• What effect does fuel changes have on the PM concentration?

• Can sootblowing be used to increase the PM concentration?

• Can and should the product feed be stopped to get near zero emissions?

• Is testing during start-up and shut-down viable?

• Can clean sample gas be used for a zero point?

• Is the zero point hypothesis (i.e., 0 mg/m3 = 4mA) valid? The zero point hypothesis is

used by the German agency, and the tests done by Eli Lilly while only combusting

natural gas support the zero point hypothesis concept.

2. Can and should multiple correlations be used in some instances when clearly the PM

characteristics change?
7-12

3. For sources having condensible materials in the exhaust stream, the PM CEMS must be

able to measure PM at the Reference Method filter temperature. If condensible PM is

included in the total particulate, in-situ PM CEMS (e.g., light scattering, probe

electrification, light extinction, and optical scintillation) may not be applicable.

In addition to PS-11, the EPA also produced QA and QC measures designed to ensure

that the ongoing PM data collected by the PM CEMS is valid. These QA/QC measures are found

in Procedure 2. The following QA/QC and data handling issues must be specified in the

applicable regulation:

1. What is the appropriate frequency for confirming the correlation (e.g., annually, every

18 months, every 5 years)? In Germany, many correlations are not checked for 5 years. 

The EPA added a 3-run Reference Method check of the correlation equation, called a

relative response audit, to be done annually.

2. What is continuous data (e.g., are four 15-minute block averages needed for an hourly

average), and how does continuous apply to batch type monitors (i.e., beta attenuation)? 

If a batch type PM CEMS samples stack gas for 9 minutes out of each 15-minute period,

is this CEMS collecting continuous data?
8-1

8.0 SUMMARY OF PS-11 AND PROCEDURE 2

The initial proposed versions of PS-11 and Procedure 2 were published in the Draft

Technical Support Document for HWC MACT Standards, Volume IV: Compliance with the

Proposed MACT Standards dated February 1996. Public comment was received, and additional

revisions were made. PS-11 and Procedure 2 were published again in December 1997. 

Additional comments were received, and EPA has continued to learn about the capabilities and

performance of PM CEMS. The following sections present EPA’s latest approach to PS-11 and

Procedure 2. EPA intends to publish a supplemental proposal for PS-11 and Procedure 2 by the

end of 2000.

8.1 PS-11

PS-11 is used for evaluating the acceptability of a PM CEMS at the time of or soon after

installation, and whenever specified in the source’s applicable regulation. This performance

specification requires site-specific correlation of the PM CEMS response against manual

gravimetric Reference Method measurements (including those made using EPA Reference

Methods 5 or 17). PS-11 outlines the procedures and acceptance criteria for installation,

operation, calculations, and reporting of data generated during a PM CEMS correlation. PS-11 is

unique, relative to the performance specifications for other CEMS because it is based on a

technique of correlating PM CEMS response to emissions determined by the Reference Method. 

This differs from a CEMS measuring gaseous pollutants which has available calibration gases of

known concentration.

As presented in Section 4 “Summary of Known PM CEMS,” several different types of PM

CEMSs, which use different operating principles, are available. The selection of an appropriate

PM CEMS is dependent on site-specific configurations, flue gas conditions, and PM

characteristics (see Section 7 “PM CEMS Implementation” for source applicability). After an

appropriate PM CEMS is selected, it must be installed at an accessible location downstream of all

pollution control equipment. The PM CEMS concentration measurements must be performed

from a location considered most representative or from one that can provide data that can be

corrected to be representative of the total PM emissions as determined by the manual Reference

Method. The site-specific correlation developed during the Performance Specification testing

must relate specific PM CEMS responses to integrated particulate loadings. 
8-2

After completing the initial field installation, the PM CEMS is operated for a Shakedown

Period. The objective of the Shakedown Period is for the facility operators to become familiar

with the PM CEMS and its routine operation for providing reliable data. The Shakedown Period

continues until the instrument technicians are comfortable with the operating characteristics of the

PM CEMS and that the PM CEMS is operating within the manufacturer’s specifications. After

completing the Shakedown Period, the PM CEMS is operated for a Correlation Test Planning

Period. The objective of this period is to identify the full range of operating conditions and PM

emissions to be used in the PM CEMS correlation test. During the Correlation Test Planning

Period the process and air pollution control equipment are operated in their normal set of

operating conditions, except when attempts are purposely made to produce higher emissions. The

Correlation Test Planning Period continues until the source owner is satisfied that the complete

range of PM emissions have occurred. During the Correlation Test Planning Period, the

operators must establish whether the monitor is operating in a suitable range(s) relative to the

source’s emission profile. The objective here is to assure that the monitor’s measurement range

is broad enough to measure peak emissions yet sensitive enough to address low-emission

conditions. Ideally the monitor should be reading near mid-scale during normal conditions but

never reading off-scale during peak emissions.

The performance of the PM CEMS is judged from the results of two tests: (1) 7-day drift

test and (2) initial correlation test. The 7-day drift test is to validate the internal performance of

the PM CEMS relative to its own zero and upscale drift checks for seven consecutive days. The

purpose of the 7-day drift measurement is to verify that the PM CEMS response is the same as

that established during the development of the initial correlation and to determine whether the PM

CEMS is in control during day-to-day operation. The initial correlation test is done to develop

the relationship between the PM CEMS responses and the manual Reference Method results over

a range of PM concentrations. Collection of Reference Method PM data using paired trains is

required. Each set of paired train results must achieve a specific level of precision to be used in

the correlation data set.

For the correlation relation tests, a minimum of 15 valid runs must be conducted, each

consisting of simultaneous PM CEMS and Reference Method measurements sets and covering the

full range of PM concentrations identified during the Correlation Test Planning Period. The
8-3

Reference Method measurements consist of paired trains operated simultaneously. For acceptable

Reference Method measurements, the paired trains must meet precision and bias criteria. Ideally,

the manual Reference Method data would be distributed over the complete operating range

experienced by the facility, with at least 20 percent of the minimum 15 measured data points in

each of the following three levels:

C Level 1: From zero PM concentration to 50 percent of the maximum PM concentration.

C Level 2: 25 to 75 percent of the maximum PM concentration.

C Level 3: 50 to 100 percent of the maximum PM concentration.

Although the above levels overlap, individual run data may only be applied in one level. 

Lower and higher than normal PM concentrations may be intentionally created by operating the

facility outside of its normal operation, but, at a minimum, the correlation data must include the

range of PM CEMS responses observed during the Correlation Test Planning Period. The

correlation relation can only be extrapolated to 125 percent of the highest PM CEMS reading

observed during the correlation test. If the PM CEMS records readings higher than 125 percent

of the highest PM CEMS reading observed during the correlation test for three consecutive hours,

three additional Reference Method test runs must be made at the higher PM CEMS response. 

The correlation relation must be revised within 30 days of the occurrence.

Developing a PM CEMS correlation will affect plant operations for about a week while

the correlation tests are being performed. PS-11 does not require the source to emit PM that

exceeds the PM emission limit during the correlation test.

From the complete set of correlation data, the correlation coefficient, confidence interval,

and tolerance interval are calculated for a polynomial and a linear regression. A test to determine

if the polynomial regression offers a statistically significant improvement to the preferred linear

regression is done. The correlation coefficient, confidence interval, and tolerance interval for the

selected regression must meet the performance criteria in PS-11.

8.2 PROCEDURE 2

40 CFR Part 60, Appendix F, Procedure 2 describes the procedures used to evaluate the

effectiveness of QA and QC procedures and the quality of the data produced by any PM CEMS

that is used for compliance monitoring. The QA/QC practices of Procedure 2 consist of
8-4

C daily drift and sample volume checks

C quarterly audit of the PM CEMS’s accuracy in response to reference standards

C quarterly audit of the measured sample volume

C longer-term assessment of the stability and applicability of the initial correlation relation.

Also included in Procedure 2 are assessments of the accuracy and precision of the

Reference Method data used in the correlation relation assessment.

Procedure 2 requires a written QA Plan that includes complete detailed QA/QC

procedures. If the PM CEMS fails to meet the acceptable criteria for any Procedure 2 audit, the

PM CEMS is called out-of-control. When the PM CEMS is out-of-control for two consecutive

periods, procedures in the QA Plan must be enhanced to prevent a repeat of the out-of-control

condition.
9-1

9.0 PM CEMS COST

The data on Tables 9-1 and 9-2 are based on actual expenditures experienced by the EPA

in field studies, information gained from interviews with users, and the expected costs of

appropriate QA/QC requirements in the draft performance specifications and associated

procedures. The tables point out that costs can vary widely, mainly according to the frequency of

the RCA. Since the costs in Tables 8 and 9 were developed, the EPA has received new

information about PM CEMS costs. The EPA believes the First Costs may be a little low because

of the potential need for more Reference Method particulate testing than originally anticipated. 

Additional test runs may be needed during the Correlation Test Planning Period in order to assess

the proper measurement range for the PM CEMS.

TABLE 9-1. IN-SITU (LIGHT SCATTERING) PM CEMS COSTSa

Task Total cost $

Total First Costs (Equipment, installation, initial

testing, correlation)

102,600 - 132,600

Total Annual Costs – RCA done every year 51,800 - 82,800

RCA done every 18 months 40,700 - 71,700

RCA done every 3 years 29,600 - 60,600

TABLE 9-2. EXTRACTIVE (BETA GAUGE) PM CEMS COSTSa

Task Total cost $

Total First Costs (Equipment, installation, initial

testing, correlation)

140,000 - 170,000

Total Annual Costs – RCA done every year 58,200 - 88,800

RCA done every 18 months 47,100 - 77,700

RCA done every 3 years 36,000 - 66,600

a Assumptions for these tables are given in Appendix A
10-1

10.0 REFERENCES

1. Act to Amend the Industrial Code and Expand the Civil Code, Federal Law Gazette

(BGB1), Part I, No. 54, December 1959

2. Breton, H., Overview of German Emission Monitoring Regulations, in Proceedings,

Continuous Emission Monitoring: Present and Future Applications, AWMA International

Specialty Conference - Chicago, pp. 44-54, 1989.

3. Conner, W.D. and Hodkins, J.R., Optical Properties and Visual Effects of Smoke-Stack

Plumes, U.S. Public Health Service Publication No. 999-AP-30, NTIS Publication

Number PB 174-705, Springfield, VA, 1967.

4. Conner, W. D., Measurement of Opacity and Mass Concentration of Particulate

Emissions by Transmissometry, EPA 650/2-74-128.

5. Conner, W.D., Knapp, K.T., and Nader, J.S., Applicability of Transmissometers to

Opacity Measurement of Emissions - Oil-fired Power Plants and Portland Cement

Plants, EPA 600/2-79-188.

6. Draft Technical Support Document for HWC MACT Standards, Vol. IV: Compliance

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APPENDIX A

BREAKDOWN OF PM CEMS COSTS
A-1

LIGHT SCATTERING PM CEMS COSTS

Task Total Cost $

Planning 3,500

Select Equipment 10,300

Provide Support Facilities 1,000 - 8,100

Purchase CEMS 36,000 - 47,100

Install & Check CEMS 9,900

Performance Spec. Tests 25,000 - 36,800

Prepare QA Plan 16,900

Total First Costs 102,600 - 132,600

Operation & Maintenance 12,900

Annual RATA (O2 monitor) 0 - 5,800

PM Monitor RCA 15,000 - 26,300

Quarterly ACA 1,000 - 7,000

Record Keeping 7,500

Annual Review & Update 1,000 - 4,400

Capital Recovery 14,364 - 18,880

Total Annual Costs 51,800 - 82,800

If RCA done every 18 months 40,700 - 71,700

If RCA done every 3 years 29,600 - 60,600
A-2

BETA GAUGE PM CEMS COSTS

Task Total Cost $

Planning 3,500

Select Equipment 10,300

Provide Support Facilities 1,000 - 8,100

Purchase CEMS 71,000 - 82,100

Install & Check CEMS 12,300

Performance Spec. Tests 25,000 - 36,800

Prepare QA Plan 16,900

Total First Costs 140,000 - 170,000

Operation & Maintenance 13,700

Annual RATA (O2 monitor) 0 - 5,800

PM Monitor RCA 15,000 - 26,000

Quarterly ACA 1,000 - 7,000

Record Keeping 7,500

Annual Review & Update 1,000 - 4,600

Capital Recovery 20,000 - 24,200

Total Annual Costs 58,200 - 88,800

If RCA done every 18 months 47,100 - 77,700

If RCA done every 3 years 36,000 - 66,600