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Air Quality in Indiana

Air Quality in Indiana > Compliance > CEMS/COMS Forms, Information and Guidance CEMS/COMS Forms, Information and Guidance

What is a CEMS?

A continuous emission monitoring system (CEMS) is the total equipment necessary for the determination of a gas or particulate matter concentration or emission rate using pollutant analyzer measurements and a conversion equation, graph, or computer program to produce results in units of the applicable emission limitation or standard. CEMS are required under some of the U.S. EPA and IDEM regulations for determinations of continuous compliance with standards, annual total emissions relative to the Federal Acid Rain program, and air pollutant reductions required by State programs.

Performance Specifications listed in 40 CFR 60 Appendix B and 40 CFR 75 are used for evaluating the acceptability of the CEMS at the time of or soon after installation and whenever specified in the regulations. Quality assurance procedures in 40 CFR 60, Appendix F and 326 IAC 3-5 are used to evaluate the effectiveness of quality control (QC) and quality assurance (QA) procedures and the quality of data produced by any CEMS that is used for determining continuous compliance with the emission standards.

What is a COMS?

A continuous opacity monitoring system (COMS) is the total equipment necessary for determining light transmittance passing through a flue gas or for measuring the optical density of the flue gas. The analyzer electronically converts the optical density, based on certain parameters, into an opacity reading expressed as % opacity. Performance Specifications listed in 40 CFR 60 Appendix B are used for evaluating the acceptability of the COMS at the time of or soon after installation and whenever specified in the regulations. Quality assurance procedures in 40 CFR 60, Appendix F and 326 IAC 3-5 are used to evaluate the effectiveness of quality control (QC) and quality assurance (QA) procedures and the quality of data produced by any COMS that is used for determining continuous compliance with the opacity standards.

Forms and Guidance