Quality Assurance
Accuracy of the system is demonstrated in several ways. An internal quality assurance check is achieved by daily introduction of a certified concentration of gas to the sample probe. The EPA also allows for the use of Continuous Emissions Monitoring Calibration Systems which dilute gases to generate calibration standards. The analyzer reading must be accurate to a certain percentage. The percent accuracy can vary, but most fall between 2.5% and 5%. In power stations affected by the Acid Rain Program, annual (or bi-annual) certification of the system must be performed by an independent firm. The firm will have an independent CEM system temporarily in place to collect emissions data in parallel with the plant CEMS. This testing is referred to as a Relative Accuracy Test Audit (RATA).
In the U.S., periodic evaluations of the equipment must be reported and recorded. This includes daily calibration error tests, daily interference tests for flow monitors, and semi-annual (or annual) RATA and bias tests.
Read more about this topic: Continuous Emissions Monitoring System
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