SO2 Precursor Gas Monitoring Training Overview

1
SO2 Precursor Gas Monitoring Training Overview

• Solomon Ricks, U.S. EPA, Office of Air Quality
  Planning and Standard, Ambient Air Monitoring
  Group
• Keith Kronmiller, Alion Science and Technology

2
Outline

• Methodology
• Laboratory test results
• Preliminary field results
• NESCAUM Guidance Document
• Operational checks
• Instrument Operations
• Summary

3
Methodology

• Why measure trace levels of SO2?
• Particulate air pollution is a complex mixture of
  small and large particles
• Fine sulfate aerosols form when SO2 condenses in
  the atmosphere

4
Methodology

• What makes a high sensitivity, or trace level,
  SO2 instrument?
• Band pass filter to increase NO rejection
• High detector sensitivity and
• Longer optical bench.

5
Methodology
Diagram of a Precursor Gas SO2 Analyzer
6
Laboratory test results
7
Laboratory Test Results
8
Laboratory Test Results
9
Laboratory Test Results
10
Laboratory Test Results
11
Laboratory Test Results
12
Ambient Data ExampleJenkins Road
13
Ambient Data ExampleJenkins Road
14
Ambient Data ExampleJenkins Road
15
Ambient Data ExampleJenkins Road
16
NESCAUM Trace SO2 Monitoring Guidance for RAIN

• Provides additional operational checks for high
  sensitivity SO2 instruments
• Offers guidance with calibration issues
• Currently in draft form
• Last revision, March 7, 2005

17
Operational checks for high sensitivity SO2
analyzers

• Is the instrument working properly?
• Response to zero air should be stable (lt 0.1 ppb)
  over intervals of 1 2 weeks
• Is the zero air free from contaminants?
• Use multiple sources of zero air use the one
  with the lowest response
• Is data acquisition accurate at low levels?
• Digital data streams are essential for trace
  levels

18
Thermo 43C-TLEDiagnostic Parameters

• DC Voltage N/A
• PMT Voltage N/A
• Internal Temp 8 - 47C
• Chamber Temp 43 - 47C
• Chamber Pressure 400 1000 mm Hg
• Sample Flow 0 1.5 LPM
• UV Lamp Intensity 10,000 50,000 Hz
• Lamp Voltage 500 1200 volts
• Optical Span Test N/A

19
Instrument Operation

• Item Schedule
• Visual inspection and cleaning
  Bi-annually
• Sample particulate filter inspection Weekly
• Verify Test Function Weekly
• Perform Level I calibration Daily
• Capillary inspection and replacement Bi-annually
• Perform flow check Bi-annually
• Fan filter inspection and cleaning Bi-annually
• Lamp voltage check Bi-annually

20
Instrument Operation
21
Interferences

• Hydrocarbon
• Fluoresces in a fashion similar to SO2 when
  exposed to UV light
• Removed through the hydrocarbon kicker
• Nitrogen oxide
• NO fluoresces in a spectral range close to SO2
• Band pass filter enhances NO rejection

22
Summary

• High sensitivity (trace level) instruments are
  commercially available for SO2
• TEI units are in production (43C-TLE)
• T-API are available for ordering with delivery
  date of 6/05 (100EU)
• SO2 high sensitivity instruments require few
  modifications
• Increased detector sensitivity and longer optical
  bench (TEI 43C-TLE)
• Pulsed UV fluorescence (T-API 100EU)

23
Summary, contd

• OAQPS has compared the high sensitivity SO2
  instruments against their stated performance
  specifications
• TEI 43C-TLE/T-API 100AS
• T-API currently developing true trace SO2
  instrument
• Other instrument(s) are available
• Ecotech
• Has not been tested by OAQPS
• Could be tested during the field portion