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EPA Precursor Gas Training Workshop SO 2 Precursor Gas Monitoring Training Overview Lewis Weinstock Solomon Ricks, U.S. EPA Office of Air Quality Planning.

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Presentation on theme: "EPA Precursor Gas Training Workshop SO 2 Precursor Gas Monitoring Training Overview Lewis Weinstock Solomon Ricks, U.S. EPA Office of Air Quality Planning."— Presentation transcript:

1 EPA Precursor Gas Training Workshop SO 2 Precursor Gas Monitoring Training Overview Lewis Weinstock Solomon Ricks, U.S. EPA Office of Air Quality Planning and Standards

2 EPA Precursor Gas Training Workshop Outline Methodology Field test results Responses to Calibrations Burden’s Creek SO 2 Frequency Distribution Instrument Operations Summary

3 EPA Precursor Gas Training Workshop Why measure trace levels of SO 2 Objectives: Emission strategy development Effectiveness of reduction strategies Validation of SO 2 and sulfate modeling predictions Long term trends analysis Health effect studies Need highly-sensitive ambient monitors deployed around these areas to determine CAIR’s effect on SO2 and related species.

4 EPA Precursor Gas Training Workshop Trace Level Sampling Challenges (SO 2 ) Performance challenges –Lower noise for reduced LDL/MDL –Reduced zero and span drift –Increased rejection of interferences Trace level modifications –Special band-pass filter to increase NO rejection –Improved light baffling to reduce stray light –More powerful UV source lamp –Higher detector sensitivity –Longer optical bench

5 EPA Precursor Gas Training Workshop Methodology (UV Light Path) SO 2 + hv 214nm SO 2 * SO 2 * SO 2 + hv 330nm

6 EPA Precursor Gas Training Workshop Methodology (General Schematic) General Diagram of a Precursor Gas SO 2 Analyzer

7 EPA Precursor Gas Training Workshop Currently Available Trace-Level SO 2 Options Teledyne-API 100EU EQSA Ecotech EC9850T EQSA Thermo Electron 43C-TLE EQSA (new model: 43i-TLE)

8 EPA Precursor Gas Training Workshop Testing Results – Field April 2006 Make/ModelThermo 43C-TLE (observed) Averaging Time60 seconds Conc. Range0-100 ppb Zero Drift (0.200 ppb/day)12 hr. (0.199 ppb) 24 hr. (0.200 ppb) Span Drift (1% FS per week)20% FS (0.06%) 80% FS (0.27%) Precision (Coefficient of Variance) 0.91% Bias+1.08% LDL (0.100 ppb)0.112 ppb Noise (0.050 ppb)0.029 ppb Linearity (1% FS. M, B, and R 2 reported) x R 2 = MDL Observed0.055 ppb (0.038 – ppb CL)

9 EPA Precursor Gas Training Workshop

10 Recertified Environics calibrator

11 EPA Precursor Gas Training Workshop Recertified Environics calibrator ?

12 EPA Precursor Gas Training Workshop Burdens Creek – Ambient Concentrations Precision Level Span Level

13 EPA Precursor Gas Training Workshop Burdens Creek – Ambient Concentrations

14 EPA Precursor Gas Training Workshop Thermo 43C-TLE Diagnostic Parameters ( )

15 EPA Precursor Gas Training Workshop Instrument Operation ItemSchedule Check diagnostics (if not available remotely)Bi-weekly Visual inspection and cleaning6 months Replace sample particulate filterBi-weekly to monthly based on PM levels Perform QC gas challenge (Level 1 and precision) Bi-weekly (daily recommended) Capillary inspection and replacement6 months Fan filter inspection and cleaning6 months depending on surroundings Lamp voltage checkWhen lamp voltage approaches maximum (1200v)

16 EPA Precursor Gas Training Workshop Interferences Hydrocarbons Fluoresces in a fashion similar to SO 2 when exposed to UV light Removed through the hydrocarbon “kicker” Nitrogen oxide NO fluoresces in a spectral range close to SO 2 Band pass filter enhances NO rejection

17 EPA Precursor Gas Training Workshop SO2 Response due to NO interference


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