CEA Air Emission Monitoring & Control 2 — Questions and Answers
Question 1: Under 40 CFR Part 75, which facilities are required to use Continuous Emission Monitoring Systems (CEMS)?
- All industrial boilers over 10 MMBtu/hr
- Electric utility steam generating units subject to the Acid Rain Program (Correct answer)
- Any facility emitting more than 100 tons/year of any criteria pollutant
- Facilities within 50 miles of a Class I area
Correct answer: Electric utility steam generating units subject to the Acid Rain Program
40 CFR Part 75 specifically requires CEMS for electric utility steam generating units regulated under the Acid Rain Program (Title IV of the CAA).
Question 2: What is the primary purpose of a Relative Accuracy Test Audit (RATA) for a CEMS?
- To calibrate the zero and span values of the analyzer
- To compare CEMS data against reference method measurements to verify accuracy (Correct answer)
- To test the data acquisition system for electronic errors
- To verify that the monitoring system meets EPA Method 19 flow requirements
Correct answer: To compare CEMS data against reference method measurements to verify accuracy
A RATA compares CEMS measurements with simultaneous reference method (stack test) measurements to verify that the CEMS accurately reflects actual emissions.
Question 3: Which EPA method is the reference method for measuring particulate matter emissions from stationary sources?
- EPA Method 6
- EPA Method 9
- EPA Method 5 (Correct answer)
- EPA Method 22
Correct answer: EPA Method 5
EPA Method 5 is the reference method for determining particulate matter emissions from stationary sources using an isokinetic sampling train.
Question 4: A stack test result shows SO2 emissions of 1.8 lb/MMBtu against a permit limit of 1.5 lb/MMBtu. What is the compliance status?
- In compliance, because results are within 20% of the limit
- Out of compliance, because measured emissions exceed the permit limit (Correct answer)
- Requires retest before a determination can be made
- In compliance if the facility has an upset provision in the permit
Correct answer: Out of compliance, because measured emissions exceed the permit limit
Measured SO2 emissions of 1.8 lb/MMBtu exceed the permit limit of 1.5 lb/MMBtu, placing the facility in noncompliance regardless of the margin.
Question 5: What does the term 'isokinetic sampling' mean in the context of stack emissions testing?
- Sampling at a rate equal to the stack gas velocity to avoid biasing particle collection (Correct answer)
- Sampling at a constant flow rate regardless of stack conditions
- Collecting samples at multiple traverse points simultaneously
- Using a heated probe to prevent condensation during sampling
Correct answer: Sampling at a rate equal to the stack gas velocity to avoid biasing particle collection
Isokinetic sampling means the sampling rate matches the stack gas velocity so that particles enter the probe in proportion to their actual concentration, avoiding size-biased errors.
Question 6: Which air pollutant is regulated as a 'hazardous air pollutant' (HAP) under Section 112 of the Clean Air Act rather than as a criteria pollutant?
- Sulfur dioxide (SO2)
- Nitrogen dioxide (NO2)
- Benzene (Correct answer)
- Ozone (O3)
Correct answer: Benzene
Benzene is listed as a hazardous air pollutant under CAA Section 112 and regulated under National Emission Standards for Hazardous Air Pollutants (NESHAP), not as a criteria pollutant.
Question 7: What is the purpose of a Cylinder Gas Audit (CGA) in CEMS quality assurance?
- To verify that stack gas flow meters are calibrated correctly
- To challenge the CEMS analyzer with a certified reference gas to check linearity (Correct answer)
- To test the data logger for clock synchronization errors
- To audit the integrity of sample lines for leaks
Correct answer: To challenge the CEMS analyzer with a certified reference gas to check linearity
A CGA introduces a certified reference gas cylinder into the CEMS to verify that the analyzer responds accurately at a concentration different from the zero/span calibration points.
CEA Air Emission Monitoring & Control 2
Under 40 CFR Part 75, which facilities are required to use Continuous Emission Monitoring Systems (CEMS)?