An Alternative Approach To Ambient Ozone Monitoring

1. An Alternative Approach To Ambient Ozone Monitoring Presenter: Patrick King Teledyne Advanced Pollution Instrumentation

2. O3 Measurement Methods • Dasibi came out with the first EPA approved equivalent photometric ozone analyzer in 1977. • Before that, the EPA Reference Method was, and still is, a chemiluminescence analyzer using Ethylene as the reagent. • Obvious issue with Reference Method – Ethylene is highly flammable, potential for serious injury.

3. What Is A 265 Ozone Analyzer? • Through close communication with our customers a need for an alternate measurement approach was identified. • Why not replace Ethylene with Nitric Oxide? Basically, the premise is based on a reverse NOx analyzer. Low cost, high precision bottles of Nitric Oxide are readily available. • Used continuously, standard cylinders of Nitric Oxide should last approximately one year, due to the low flow rate of 5 cm3/min.

4. 265 Pneumatic Design

5. 265 Sample Flow Path

6. 265 Azero Flow Path

7. 265 Nitric Oxide Flow Path

8. Why A Chemi-Ozone Analyzer? • Known Photometric Interferants: Many compounds absorb photons as well or better than ozone at 254 nm. • ClO2 • Mercury • Tetrahydrofuran • Turpines • Other VOC’s • UV photometric analyzers experience large wet dry episodes, especially when switching between wet sample and dry calibration gases.

9. Prospective Customers • Example1: Customers who are marginal in their ozone attainment. • Example 2:In pine forests. • Pine trees emit turpines at night • Example 3:In natural gas fields. • Gas wells have large amounts of mercury • Example 4:In welding operations. • Arc welding makes both O3 as well as fine particulates. • Example 5: In areas with high VOC backgrounds. • Example 6:Near polyvinyl chloride (PVC) plants. • The solvent for PVC is tetrahydrofuran

10. Interference Study • Houston TCEQ Study: A hydrocarbon spike experiment was carried out to examine how organic compounds might interfere with ozone monitors. A mixture of 21 C2 - C8 hydrocarbons was used to challenge the instruments being compared by our study, as well as two TCEQ UV ozone monitors. The total hydrocarbon concentration was 1.4 ppmV, and the individual species concentrations were 66 ppbV each. All instruments were first zeroed and then spanned at 100 ppb. The input ozone concentration was then set to 30 ppb, and the hydrocarbon mixture was used to challenge the ozone monitors. • Species Contained In Mixture:

11. Interference Study Results

12. Product Specifications • Ranges: 0-100 ppb to 0-2000 ppb • Zero Noise: <0.3 ppb (RMS) • Span Noise: <0.5% of reading above 100 ppb • Linearity: <1% of Full Scale • Precision: <0.5% of reading • Rise/Fall time: < 20 Seconds to 95% • Sample Flow: 500 cm3/min • Reagent Flow: 5 cm3/min

13. Linearity Data

14. Comparison Data

15. Noise And Drift Data

16. Field Comparison Data

17. What’s Next? • Supart C submission in place, awaiting USEPA equivalency approval. • Discussing possible submission as an alternate reference method. • Currently CE certification compliant. • Questions?