Characterization of a High Performance Zero Air Generator

1. Characterization of a High Performance Zero Air Generator Stephen Toner, Ph. D. Senior Chemist / Development Engineer at Teledyne - API March 4, 2009 2009 National Air Quality Conference – Dallas, Texas

2. Outline • Introduction • Need for Zero Air • How a Zero Air Generator works • Need for Characterization • Experimental Setup • Two different methods for characterizing zero air generator performance • Results and Discussion • Results from both experimental methods • What these results mean for the zero air generator performance • Conclusions • Future Directions © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

3. Need for Zero Air • Having a source of Zero Air is important for a variety of reasons • Instrument Calibration • Ever since the first instruments were made to monitor air pollution there had to be a way of calibrating them • Deliver some known concentration of the analyte gas (span gas) • Deliver clean, pollutant-free air to the instrument for zeroing • Instrument QA/QC • Examining noise and any baseline drift for the instrument © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

4. Need for Zero Air • Methods by which Zeroing can be obtained • Have a bottle of clean, zero air on site • This is fine as long as long zeros are not required or if there are not multiple instruments • Can get expensive over long term • Have your own “in-house” clean air system • More typical for research lab or larger operation environments • Use a compressor and system of scrubbers • Great source of clean air at high flow • Not always very transportable, nor do they typically fit in small monitoring shelters • Transportable Rack-mount Zero Air Generators • Same concept as the in-house clean air system, but in a much smaller package and can fit in sampling shelters © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

5. How a Zero Air Generator Works Teledyne – API Model 701H • Dry incoming air • store dry air in compressor tank • Scrubber for oxidizing CO and hydrocarbons to CO2 • Scrubber for oxidizing NO to NO2 • Scrubber to remove SO2, NO2, hydrocarbons, etc… • Filter PM on output © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

6. Need for Characterization • What is Zero? • This is a lingering question with the current gas phase instrumentation available • zero can only be measured down to the LDL of the instrument used • Do all Zero Air Generators work the same? • Unfortunately, the answer is No • Zero Air Generator performance is dependent on material used (line, fitting, housing material; scrubber types and quantity) as well as flow throughput • Age and environment can be a factor if proper upkeep is not followed © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

7. Need for Characterization • Purpose of this study: • To characterize the output of a high performance zero air generator using highly sensitive gas phase monitoring instrumentation • Examine the zero air generators ability to continue delivering clean zero air under highly elevated pollution conditions • Focus on quantifying National Ambient Air Quality Standard (NAAQS) criteria pollutants (SO2, NO2, CO, & O3) as well as nitric oxide (NO) and volatile organic compounds (VOCs). • Studies similar to this must have been conducted before • Some info found in zero air generator brochures • No publications in peer reviewed literature? © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

8. Experimental • Characterization carried out in two parts… • Zero Air Generator versus Synthetically Produced Zero Air • - The zero air output of the M701H was compared to a synthetically produced zero air in order to examine if there is any production, or ambient breakthrough, of SO2, NO2, CO, O3, NO, or VOCs. • Pollution Breakthrough Tests • - Introduce known concentrations of pollutants (SO2, NO2, CO, O3, NO, or VOCs) to the intake of the M701H to assess the M701H’s ability to scrub such levels of pollution. © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

9. Experimental Setup – Zero vs Synthetic Air M100EU = trace SO2 M200EU = trace NO/NO2 M300EU = trace CO M400E = O3 DANI 462 = VOCs M701H output for VOC generation was also collected in SUMMA canisters and analyzed by GC-MS by Test America Laboratories • A) Synthetic air was produced by mixing pure N2 and O2 at 79% and 21% • Each instrument sampled off the synthetic zero air for several days to establish a good statistical baseline for “zero” and to examine zero drift (if any) for each instrument • B) Each instrument was then subjected to sampling M701H zero air for (at least) an equal amount of time as the synthetic zero air • Used multiport sampling manifold to allow for multiple instruments at once • Teledyne – API M700E mass flow calibrator used for M701H flow control © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

10. Experimental Setup – Breakthrough Tests M100EU = trace SO2 M200EU = trace NO/NO2 M300EU = trace CO M400E = O3 M701H output for VOC breakthrough testing was collected in SUMMA canisters and analyzed by GC-MS by Test America Laboratories • Known levels of pollutants (SO2, NO2, NO, CO, O3, and VOCs) were introduced into the intake of the M701H intake to assess the M701H’s ability to scrub such levels of each pollutant. • Gas mixing/dilution setup was created prior to, and in-line with, the intake of the M701H (as diagramed above) • Evaluations were performed one pollutant at a time with just the specific instrument for the target gas species. • In the case where a pollutant has a known interference with another instrument, both the primary measurement instrument for the target gas and the instrument that can detect the gas as an interferent were run together. © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

11. Experimental Setup – Breakthrough Tests • The levels of pollutants to be introduced to the M701H were based on: • National Ambient Air Quality Standard (NAAQS) and Air Quality Index (AQI) levels for the criteria gas pollutants (SO2, NO2, CO, and O3) • Occupational Safety and Health Administration (OSHA) permissible exposure limits (PELs) for each criteria pollutant as well as NO and VOCs. • Extreme levels above NAAQS by doubling OSHA PELs © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

12. Results – Zero Air vs. Synthetic Air © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

13. Results – Zero Air vs. Synthetic Air • No difference between M701H zero air and synthetic zero air baselines • The average baseline trend for each temporal series never deviates from zero (beyond the standard noise of the instrument) • These results also show that there is no generation of SO2, NO, NO2, CO, or O3 from the M701H • Also shows that there is no “drift” for any of the analyzers © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

14. Sulfur Dioxide Breakthrough Tests Pollutant ConcNAAQS, AQI, or OSHA CriteriaFlowSample Time 30 ppb SO2 NAAQS annual mean primary standard 5-lpm 2.5 hours 140 ppb SO2 NAAQS 24-hr primary standard 5-lpm 2 hours 500 ppb SO2 NAAQS 3-hr secondary standard 5-lpm 1 hour 5 ppm SO2 OSHA PEL 5-lpm 2.5 hours 10 ppm SO2 2x OSHA PEL 5-lpm 1.7 hours 10 ppm SO2 2x OSHA PEL 10-lpm 1 hour © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

15. Nitrogen Dioxide Breakthrough Tests Pollutant ConcNAAQS, AQI, or OSHA CriteriaFlowSample Time 53 ppb NO2 NAAQS annual mean primary standard 5-lpm 2.2 hours 2 ppm NO2 Upper hazardous category of AQI 5-lpm 18.5 hours 2 ppm NO2 Upper hazardous category of AQI 10-lpm 2 hours 10 ppm NO2 2x OSHA PEL 5-lpm 2 hours 10 ppm NO2 2x OSHA PEL 10-lpm 19.6 hours 50 ppm NO 2x OSHA PEL 5-lpm 2 hours 50 ppm NO 2x OSHA PEL 10-lpm 1 hour © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

16. Carbon Monoxide Breakthrough Tests Pollutant ConcNAAQS, AQI, or OSHA CriteriaFlowSample Time 35 ppm CO NAAQS 1-hour primary standard 5-lpm 2 hours 50 ppm CO OSHA PEL 5-lpm 1.1 hours 50 ppm CO OSHA PEL 10-lpm 2.75 hours 100 ppm CO 2x OSHA PEL 5-lpm 2.1 hours © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

17. Ozone Breakthrough Tests Pollutant ConcNAAQS, AQI, or OSHA CriteriaFlowSample Time 140 ppb O3 20 ppb above NAAQS 1-hour primary std 5-lpm 1.5 hours 200 ppb O3 2x OSHA PEL 5-lpm 1.5 hours © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

18. VOC Breakthrough Test ConcOSHA Criteria 20 ppm 2x OSHA 8-hour PEL for Benzene 22 ppm 2x OSHA 8-hour PEL for Benzene 155 ppm 3x OSHA acceptable 10-min duration max for Benzene VOC mixture = benzene, toluene, 2-butanone, chloromethane, dichloromethane, dichlorofluoromethane, trichlorofluoromethane • All M701H samples yield “ND” • Only detectable species in room air “control” sample • 20-lpm samples to test the scrubbing capabilities of the HC scrubber at high flow © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

19. VOC Breakthrough Test ConcOSHA Criteria 20 ppm 2x OSHA 8-hour PEL for Benzene 22 ppm 2x OSHA 8-hour PEL for Benzene 155 ppm 3x OSHA acceptable 10-min duration max for Benzene VOC mixture = benzene, toluene, 2-butanone, chloromethane, dichloromethane, dichlorofluoromethane, trichlorofluoromethane • All M701H samples yield “ND” • Only detectable species in room air “control” sample • 20-lpm samples to test the scrubbing capabilities of the HC scrubber at high flow © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

20. Pollutant Breakthrough Tests - Summary • There is no deviation from the average baseline when SO2, NO, NO2, CO, or O3 are introduced to the inlet of the M701H • This is a clear indication that there is no breakthrough of any of the introduced pollutants even at levels as high as 2x the OSHA PEL • NO2 tested for such a long length of time as it is scrubbed by activated carbon • Activated carbon is not regenerative and is used to scrub several other gas phase species • The high level of NO2 at this length of time was a longevity test and is equivalent to over a year of ambient intake of NO2 at or below NAAQS levels (note: the scrubbers in the M701H were the same for all of these tests and were never changed out) © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

21. Conclusions • The results obtained from this study show that the M701H zero air generator does not produce any of the target pollutant species within the detectable limits of the instrumentation used • Additionally, under conditions where the M701H intake is subjected to air containing elevated levels of the target pollutants, there is no breakthrough of such species that can be detected by the instrumentation used • Since the analytical instrumentation used for these experiments are among the most sensitive techniques available for the target pollutants specified, this is further verification that the M701H produces very “pure” zero air, even under extreme pollution conditions. © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

22. Future Directions • More tests at higher flows and longer durations • Run at high flow and concentrations until there is detectable breakthrough • Allows for more accurate determination of lifetime • Resource time becomes an issue • Test along with zero air generators from other manufacturers • How do they all compare? • Additional VOC tests including lighter molecular weight species (i.e. CH4) • Characterize output for aerosols • The M701H should deliver particle free air • at least for particles above 100nm © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

23. Acknowledgements • Teledyne – API Engineering & Sales • - Jeff Franks - Pat King - Bill Taylor • - David Neuschuler - Mark Cogan • - Bob Wooten - Martin Abbott • Robin Becker - Larry Foster • Test America Laboratories • - Beth Riley - Stephanie Stimson © 2009 Teledyne - Advanced Pollution Instrumentation, Inc.

24. Thank You