"Accuracy" means the extent to which the results of a calculation or the readings of an instrument approach the true values of the calculated or measured quantities, and are free from error.
"Analyzer" is the system that measures gas concentration in the discharge gas stream.
"Availability" means the number of valid hours divided by the number of hours that the EGU burns fuel.
"Backfilling" means a technique to substitute data during an out-of-control period.
"Bias" means systematic error, resulting in measurements that are either consistently low or high relative to the reference value. Bias exists when the difference between the CEM data and the reference method data exceeds random error.
"Calibration gas" means a known concentration of (1) a gas that is traceable to either a standard reference material or the U.S. National Institute of Standards and Technology, (2) an authorized certified reference gas, or (3) a U.S. Environmental Protection Agency protocol gas.
"Conditioning period" means a recommended 168-hour period following the installation of a new CEM system, during which the system samples and analyzes the emissions from the EGU, prior to the operational test period.
"Continuous emission monitoring system (CEM system)" means the complete equipment for sampling, conditioning, and analyzing emissions or process parameters and for recording data.
"Drift" means an undesired change in output, over a period of time, that is unrelated to input or equipment adjustments.
"Flow monitor" is the system that monitors the actual linear velocity or flow rate of the discharge gas stream.
"Full scale" means the upper value of the monitor or analyzer range.
"Interference rejection" means the ability of a CEM system to measure a gaseous species without responding to other gases or substances, within specified limits.
"Load" means the gross electrical and thermal output from an EGU.
"Operational test period" means a mandatory 168-hour period following the installation of a new CEM system, during which most of the performance specification tests are carried out.
"Out-of-control period" means a period when the output from the analyzer, flow monitor, or data acquisition system does not accurately represent the stack emissions.
"Precision" means the measure of the range of values of a set of repeated measurements; indicates reproducibility of the observations.
"Range" means the algebraic difference between the upper and lower limit of the group of values within which a quantity is measured, received, or transmitted.
"Relative accuracy" is the absolute mean difference between a series of concurrent measurements made by a CEM system and an applicable reference method plus the 2.5% error confidence internal coefficient, divided by the mean of the reference method measurements.
"Representative load" is the typical EGU operating level forecasted for the following 6 months.
"Standard conditions" means at 101.325 kPa pressure and 25°C temperature.
"Traceable" means the ability to relate individual measurement results, through a contiguous sequence of measurement accuracy verifications, to nationally or internationally accepted measurement systems (e.g., NIST, ISO).
"U.S. Environmental Protection Agency (EPA) protocol grade gas" means a calibration gas mixture prepared and analyzed according to Section 2 of the EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards, September 1997, EPA-600/R-97/121.
"Valid hour" means an hour during which the EGU burned fuel and the associated CEM system produced a minimum of 30 minutes of valid data. In the case of a time-shared CEM system, the minimum requirement is two data points per valid hour.