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PERFORMANCE SPECIFICATION 4A - SPECIFICATIONS AND TEST

PROCEDURES FOR CARBON MONOXIDE CONTINUOUS EMISSION

MONITORING SYSTEMS IN STATIONARY SOURCES

1.0 Scope and Application.

1.1 Analytes.

Analyte CAS No.

Carbon Monoxide

(CO)

630-80-0

1.2 Applicability.

1.2.1 This specification is for evaluating the

acceptability of carbon monoxide (CO) continuous emission

monitoring systems (CEMS) at the time of installation or

soon after and whenever specified in an applicable subpart

of the regulations. This specification was developed

primarily for CEMS that comply with low emission standards

(less than 200 ppmv).

1.2.2 This specification is not designed to evaluate

the installed CEMS performance over an extended period of

time nor does it identify specific calibration techniques

and other auxiliary procedures to assess CEMS performance. 

The source owner or operator is responsible to calibrate,

maintain, and operate the CEMS. The Administrator may

require, under Section 114 of the Act, the source owner or

operator to conduct CEMS performance evaluations at other

times besides the initial test to evaluate CEMS performance. 

See 40 CFR Part 60, Section 60.13(c).
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1.2.3 The definitions, performance specification,

test procedures, calculations and data analysis procedures

for determining calibration drifts (CD) and relative

accuracy (RA), of Performance Specification 2 (PS 2),

Sections 3, 8.0, and 12, respectively, apply to this

specification.

2.0 Summary of Performance Specification. 

The CD and RA tests are conducted to determine

conformance of the CEMS to the specification.

3.0 Definitions. 

Same as in Section 3.0 of PS 2.

4.0 Interferences. [Reserved]

5.0 Safety. 

This performance specification may involve hazardous

materials, operations, and equipment. This performance

specification may not address all of the safety problems

associated with its use. It is the responsibility of the

user to establish appropriate safety and health practices

and determine the applicable regulatory limitations prior to

performing this performance specification. The CEMS users

manual should be consulted for specific precautions to be

taken with regard to the analytical procedures.

6.0 Equipment and Supplies. 
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Same as Section 6.0 of PS 2 with the following

additions.

6.1 Data Recorder Scale. 

6.1.1 This specification is the same as Section 6.1

of PS 2. The CEMS shall be capable of measuring emission

levels under normal conditions and under periods of shortduration peaks of high concentrations. This dual-range

capability may be met using two separate analyzers (one for

each range) or by using dual-range units which have the

capability of measuring both levels with a single unit. In

the latter case, when the reading goes above the full-scale

measurement value of the lower range, the higher-range

operation shall be started automatically. The CEMS recorder

range must include zero and a high-level value. Under

applications of consistent low emissions, a single-range

analyzer is allowed provided normal and spike emissions can

be quantified. In this case, set an appropriate high-level

value to include all emissions.

6.1.2 For the low-range scale of dual-range units,

the high-level value shall be between 1.5 times the

pollutant concentration corresponding to the emission

standard level and the span value. For the high-range

scale, the high-level value shall be set at 2000 ppm, as a

minimum, and the range shall include the level of the span
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value. There shall be no concentration gap between the lowand high- range scales.

7.0 Reagents and Standards. 

Same as Section 7.0 of PS 2.

8.0 Sample Collection, Preservation, Storage, and

Transport.

8.1 Relative Accuracy Test Procedure. Sampling

Strategy for reference method (RM) Tests, Number of RM

Tests, and Correlation of RM and CEMS Data are the same as

PS 2, Sections 8.4.3, 8.4.4, and 8.4.5, respectively.

8.2 Reference Methods. Unless otherwise specified in

an applicable subpart of the regulation, Methods 10, 10A,

10B, or other approved alternative is the RM for this PS. 

When evaluating nondispersive infrared CEMS using Method 10

as the RM, the alternative interference trap specified in

Section 16.0 of Method 10 shall be used. 

8.3 Response Time Test Procedure. The response time

test applies to all types of CEMS, but will generally have

significance only for extractive systems.

8.3.1 Introduce zero gas into the analyzer. When the

system output has stabilized (no change greater than 1

percent of full scale for 30 sec), introduce an upscale

calibration gas and wait for a stable value. Record the

time (upscale response time) required to reach 95 percent of
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the final stable value. Next, reintroduce the zero gas and

wait for a stable reading before recording the response time

(downscale response time). Repeat the entire procedure

three times and determine the mean upscale and downscale

response times. The slower or longer of the two means is

the system response time.

8.4 Interference Check. The CEMS must be shown to be

free from the effects of any interferences.

9.0 Quality Control. [Reserved] 

10.0 Calibration and Standardization. [Reserved]

11.0 Analytical Procedure. 

Sample collection and analysis are concurrent for this

performance specification (see Section 8.0). Refer to the

RM for specific analytical procedures.

12.0 Calculations and Data Analysis. Same as Section 12.0

of PS 2.

13.0 Method Performance. 

13.1 Calibration Drift. The CEMS calibration must

not drift or deviate from the reference value of the

calibration gas, gas cell, or optical filter by more than 5

percent of the established span value for 6 out of 7 test

days. 

13.2 Relative Accuracy. The RA of the CEMS must be

no greater than 10 percent when the average RM value is used
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to calculate RA, 5 percent when the applicable emission

standard is used to calculate RA, or within 5 ppmv when the

RA is calculated as the absolute average difference between

the RM and CEMS plus the 2.5 percent confidence coefficient.

13.3 Response Time. The CEMS response time shall not

exceed 1.5 min to achieve 95 percent of the final stable

value. 

14.0 Pollution Prevention. [Reserved]

15.0 Waste Management. [Reserved]

16.0 Alternative Procedures. 

16.1 Under conditions where the average CO emissions

are less than 10 percent of the standard and this is

verified by Method 10, a cylinder gas audit may be performed

in place of the RA test to determine compliance with these

limits. In this case, the cylinder gas shall contain CO in

12 percent carbon dioxide as an interference check. If this

option is exercised, Method 10 must be used to verify that

emission levels are less than 10 percent of the standard.

17.0 References. 

Same as Section 17 of PS 4.

18.0 Tables, Diagrams, Flowcharts, and Validation Data. 

Same as Section 18.0 of PS 2.