1. BAM-1022 Continuous Beta Gauge
David Gobeli, Ph.D., Thomas Pottberg
Met One Instruments, Inc.
Grants Pass Oregon USA

2. Agenda
Challenges facing continuous aerosol monitors under real-world conditions
Moisture effect on measurement
EPA field test of BAM-1022 continuous beta gauge
Additional field testing along Gulf Coast under very high dew point conditions

3. Design Challenges in Criteria PM Monitor Design
Must provide accurate reliable results under a wide variety of climactic conditions and aerosol types
Testing at additional sites besides those required by EPA are useful validate known operating range to include very hot, humid regions such as US Gulf Coast
Complexity, reliability, sensitivity, and accuracy considerations/tradeoffs

4. Class 3 PM2.5 Field Test 5 Test Campaigns, 4 Test Sites
Site A (Mira Loma CA) – winter, summer
Site B (Salt Lake City UT) – winter
Site C (Dearborn MI) – winter
Site D (Elizabeth NJ) – summer
Site “E” (Baton Rouge LA) – year round

5. Salt Lake City UT – Winter 2012

6. Baton Rouge LA

7. Moisture Effect Approach Cost Complexity Issues Control Lower
Requires elevated temperature
Compensation
Higher
Incomplete/unreliable
Removal
Very High
High
Reliability
In-Situ
Low
Very Low
None

8. Moisture Control Temperature – based (usually elevated)
Humidity – temperature adjusted to maintain set point
Combination of temperature and humidity

9. Moisture Compensation
Background will vary based upon moisture content (instrument artifact)
Artifacts can be subtracted out.
Water could bind to PM and skew results if humidity too high.
Cannot be subtracted out.

10. Moisture Removal
Moisture removed using physical means (PermaPure Drier)

11. BAM-1022 Approach Extremely simple
Measurement is made under near-ambient “in-situ” conditions.
Only slight warming to prevent condensation
Nearly eliminates moisture interference
Eliminates under-measurement due to excessive heating

12. Mira Loma, CA (Winter, Summer 2012)

13. Salt Lake City UT (Winter, 2012)

14. Dearborn MI (Winter, 2012) Regression statistics
Slope1
Intercept2
Correlation (r)
Statistics for this test site:
0.947
-0.395
Limits for
Upper:
1.100
2.000
PM2.5 Class III
Lower:
0.900
-1.346
Test Results (Pass/Fail):
PASS

15. Elizabeth NJ (Summer, 2012)

16. Ambient Moisture Measured as
Partial pressure of H2O in the atmosphere
Temperature and relative humidity
Dew Point

17. Test Site Dew Point Conditions

18. Baton Rouge Test Site
Indicative of Gulf Coast/Southeast US Weather Conditions
Extremely high dew point during summer months
Wildly varying dew point and temperature during winter months
EPA “Class 3” style field test performed for almost 1 year
Triplicate BAM-1022 monitors & FRM samplers
Strict collocation, all Class 3 protocols followed

19. Baton Rouge – Dew Point

20. All Data

21. Summer Only

22. Winter Only

23. Summary
Additional test sites demonstrates “in-situ” approach under expanded ambient/climactic conditions
Baton Rouge site conditions unlikely to be duplicated in EPA sites A-D for Class 3 test.
Additional testing currently underway for ultra-high sensitivity version with PTFE filter media.

24. Questions ?