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Sensor Evaluations (Background and Update on Select Efforts)

Sensor Evaluations (Background and Update on Select Efforts). Ron Williams Office of Research and Development National Exposure Research Laboratory Annual Region 4 Meeting October 30, 2013. Emerging Technology Researchers (Cross ORD Effort-ACE EM2 and #EM3). Ron Williams Gayle Hagler

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Sensor Evaluations (Background and Update on Select Efforts)

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  1. Sensor Evaluations(Background and Update on Select Efforts) Ron Williams Office of Research and Development National Exposure Research Laboratory Annual Region 4 Meeting October 30, 2013

  2. Emerging Technology Researchers(Cross ORD Effort-ACE EM2 and #EM3) Ron Williams Gayle Hagler Emily Snyder Tim Watkins Paul Solomon Eben Thoma Dena Vallano Brian Gullett Bill Mitchell Russell Long Melinda Beaver Vasu Kilaru ORD Innovation Office (Preuss et al)

  3. Background • Real time or continuous monitoring technologies of gases and particulates were of interest (no laboratory analysis) • Generally only lower-cost (<10 K, most under $2500) systems are being investigated • Lower-cost gas sensors employ electrochemical, metal oxide, spectroscopic sensing principles • Lower-cost PM sensors employ light scattering or light absorption sensing principles • Extensive discussions with manufacturers about their product’s capabilities

  4. New technologies for portable monitoring and/or sensor networks CO, NO2, O3, VOCs CO, NO2 Mike Hannigan – Univ. of Colorado Michael Heimbinder, Habitat Map, Brooklyn NY Sensor networks for source emissions, EPA/ORD CO VOCs

  5. Purpose of FY 13 Sensor and Applications Evaluation Collaboration Foster the development of emerging low cost measurement technologies Continue the dialogue with invention teams established at the 2012 Applications and Sensors for Air Pollutants (ASAP) workshop Provide for the technology transfer relative to evaluation protocols useful for invention teams to perform on their own Evaluate select ozone and nitrogen dioxide sensors and applications versus known FRM/FEM instrumentation Provide for individual (confidential) technical feedback on distinct evaluation parameters Allow for a potential general summarization of sensor types and their potential usefulness for various monitoring applications 1 2 3 4 5 6

  6. Opportunities • Under EPA’s Air Sensors Evaluation Project the following are being determined for lower-cost O3 and NO2 sensors: • Linearity (range) • Precision of measurements • Lower detectable limit • Resolution (noise) • Response time (lag and rise time) • RH and temperature influence • Interference equivalent CairClip electrochemical sensor evaluated under the Air Sensors Project

  7. Technical Aspects – Chamber • Ace Glass Chamber • 6” i.d. • 18” mixing chamber • 24” exposure chamber • 4 external ports for reference/interference analyzers, temperature, RH • Apps/sensors placed on mesh platform for exposure • Two chambers can be separated for apps/sensors deployment • Chamber operated in a continuous flow through mode • Test Atmosphere Introduction • NO2, SO2 obtained from EPA protocol compressed gas cylinders • O3 obtained form NIST traceable ozone generator w/photometer • Dynamic dilution calibrator and zero air generator used to dilute gases to desired concentration • All test gases (dry and humidified) introduced into 18” mixing chamber

  8. Typical Sensor Evaluation Set-Up

  9. Unique Qualities • Battery life. It is apparent that a wide range of battery options are being used. Operating periods from 3 hrs to 24 hrs have been observed • Recharge issues. Very specific recharge requirements (USB to use of transformed outlet voltage) and recharge times • Orientation. Some devices had to have a very specific orientation in the exposure chamber

  10. Unique Qualities • Sensor Interface. Some of the sensors required a discreet movement of air flow over the surface of the sensor. (Goldilocks requirement= not too much, not too little). Interface stagnation versus physical influence (cooling of sensor influences resistance and therefore output had to be considered individually for each sensor. • Test range. There appears to be a wide range in sensor sensitivities

  11. Communication Protocols • WiFi, Bluetooth, hard line (direct interface with laptop, tablet or other device), flash drive download, on-screen • Communication protocols were often less than foolproof and work around solutions had to be developed. Internal wireless security issues, cell-based signal strength and other factors had to be resolved (all were resolved)

  12. Data Recovery/Processing • Raw data processing (even reporting in some cases) often required interface with proprietary software data management programs. Such links prevented direct access to raw data and represented another communications linkage that had to be resolved • Difficultly in some situations to get to raw data as the raw signal was processed via developer’s software prior to being “reported” back to user

  13. Example Basic Performance Characteristics 2BO3 Response (ppb) Seconds

  14. Some Results An example of sensor versus FRM comparison Results from the evaluation of CairClip an electrochemical sensor for O3

  15. Example of Performance Characteristics

  16. New Sensor Research • A host of low cost (<$2500) PM2.5 and VOC sensors purchased or acquired for laboratory and/or field evaluation • PM Sensors include: RTI µPEM, Dylos, Met One 831, Carnegie-Mellon Speck, Carpol PM; AirBase; EcoPM • VOC Sensors include: AirBase; SensarisEcoSense; Cairpol VOC, Unitec, APPCD, Sensotran, ToxRAE • Research involves collaborations with NRMRL (Triple Oaks site) and OAQPS (AIRS) to leverage reference monitor collocation. Field work may be completed in CY 2013 • Findings will be fully available for publication

  17. Scope of Work • PM: Direct comparison with FEM in field setting (AIRS) • VOC: Laboratory evaluation versus benzene and multi-component gas mixture in chamber. Determine basic ability of the device to systematically respond to a VOC challenge • VOC: Devices capable of some repetitive response to VOC challenge then collocated with VOC reference monitor for BTEX comparison at near road site (Three Oaks)

  18. Source-Related Sensor Research • Ongoing sensor testing (CO, CO2) and sensor network tests to support prescribed fire emission studies (POC: Bill Mitchell) Burn Block 2 ~$10K reference analyzer $20 CO sensor (Johnson et al., 2013)

  19. European Findings

  20. Village Green Project

  21. EPA R&D: Village Green Project Solar-powered, air and meteorology monitoring bench: - Sustainable materials: manufactured from recycled milk jugs - Tamper-proof: Instruments secured in bench or base of play structure - Designed to add value to public environments (bench)

  22. Alternative designs Contract: ARCADIS / SafeplaySystemsTM

  23. Provide Direct Environmental Awareness(MOU with Durham County)with siting at a public library

  24. Website – minute-by-minute updates villagegreen.epa.gov Educational and community outreach opportunity

  25. Website – how has the air been lately? Transitioned from mostly sunny and dry to stormy weather for July 1-7, hot and sunny on July 8 Diurnal up/down trends for ozone are driven by sun-driven chemistry; both ozone and PM also affected by vertical mixing

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