1. EPA Precursor Gas Training Workshop NCore Calibration Issues Meeting the new QC Requirements Lewis Weinstock and Dennis Mikel EPA Office of Air Quality, Planning and Standards

2. EPA Precursor Gas Training Workshop Overview of NCore technical requirements Mass Flow Controllers (MFC) Calibrators Compressed Gas Cylinders Zero Air Generators Summary Key Topics

3. EPA Precursor Gas Training Workshop NCore Calibration Challenges Operating analyzers on lower ranges where ambient data are more affected by instrument drift and interferences –Old CO range 0 – 50 ppm for NAAQS compliance –Typical NCore CO range 0 – 5 ppm or even lower More frequent QC checks advised so calibration automation is important Integration of data systems and calibrators important for QC validation and timely reporting of problems Calibration standard certification periods are shorter for lower concentration standards Zero air purity is more critical than ever Reviewing your calibrator capabilities and potentially upgrading hardware may be the most important part of designing and implementing a successful NCore gas monitoring system

4. EPA Precursor Gas Training Workshop QC Checks (Precision): –Required (40 CFR 58 Appendix A) –Minimum: Once every two weeks – daily is recommended –Daily Level 1 Zero and Spans recommended Multi-point calibrations: –Quarterly (according to TAD) or if drift is an ongoing issue –Draft MQO Table - 1 in 6 months, upon instrument startup, repair, or exceeded drift tolerance MDL Tests (New requirement): –Annually or after major analyzer repair Consider entire system when troubleshooting QC problems – zero air or calibrator issues may be the cause –Don’t just recalibrate repeatedly when analyzer drift and/or linearity problems are indicated NCore Calibration and QC Check Requirements

5. EPA Precursor Gas Training Workshop ItemCOSO2NOy Full Scale Range0 to 5000 ppb0 to 100 ppb0 to 200 ppb Cylinder concentration 200 – 300 ppm10 - 15 ppm10 – 30 ppm Calibration ranges Zero (action tolerance) + 40 ppb+ 0.100 ppb+ 0.050 ppb Level I Span (action tolerance) 4500 ppb + 10% 90 ppb + 10% 180 ppb + 10% Mid Point Span2500 ppb50 ppb100 ppb Precision Level250 - 500 ppb5 - 10 ppb20 - 40 ppb Measurement Uncertainty Goal 10% upper 90 percent confidence limit for CV 10% upper 90 percent confidence limit for CV 10% upper 90 percent confidence limit for CV Calibration and QC Check Concentrations* * For a typical urban NCore station

6. EPA Precursor Gas Training Workshop Example QC Control Chart

7. EPA Precursor Gas Training Workshop Method Detection Limit Test (How do you run it?) Use a concentration of 2.5 to 5 times the instrument signal/noise Run zero gas through analyzer Dilute the calibration gas to estimated concentration level and collect readings for a predetermined length of time: –Suggested: 20-25 1 minute observations, repeated 7 times over the course of 5 -14 days. Average the concentration from these readings. Calculate the MDL as: Where represents the 99th quantile of a Student’s t distribution with (n-1) degrees of freedom and n represents the number of replicate measurements and s is the standard deviation.

8. EPA Precursor Gas Training Workshop Method Detection Limit Test Confirms that a trace-level analyzer is really performing as a trace level –Perform as part of acceptance testing –Annually as part of regular QA program –After a major repair such as detector replacement Operational challenges –Need to accurately and repeatedly generate a very small concentration –Will need dedicated low-level gas cylinder standards in the 1 ppm range for NO and SO2, and 10 ppm range for CO Agencies can share cylinders Possible development of cylinder “bank” –Dilution challenges capacity of zero air scrubbing system at high flows (~ 20 LPM)

9. EPA Precursor Gas Training Workshop Example Method Detection Limit Test MDL = (2.764) * 5.26 = 14.54 ppb Student's t-distribution From Wikipedia, the free encyclopedia

10. EPA Precursor Gas Training Workshop Typical Mass Flow Controller (MFC) Theory Calibrator Diagram Zero Air MFC

11. EPA Precursor Gas Training Workshop Calibrator Critical Specifications Gas Flow – 0 to 100 cc/min Air Flow – 0 – 20 L/min Multiple Gas ports - optional Built in traceable ozone generator Accuracy +/- 1% Full Scale Precision +/- 1% Full Scale Linearity +/- 1% Full Scale Environics 9100

12. EPA Precursor Gas Training Workshop Calibrator Specification Matrix (EPA Research 2006) CalibratorGas* Flow Air* Flow Gas input Ports Ozone Gen. Flow Accuracy Flow Precision Linearity Ecotech 1100 0-500 sccm 0-20 lpm4 Std.Yes, 0 – 1ppm +/- 1.0% Full Scale +/- 0.15% Full Scale 0.15% Full Scale Environics 9100 0-100 sccm 0-20 lpm2 Std.Yes, 0.5 – 1.25 ppm +/- 1.0% Full Scale +/- 1.0% Full Scale 1.0% Full Scale Sabio 4010L 0-1000 sccm 0-20 lpmYesYes, 0 – 2 ppm +/- 1.0% Full Scale +/- 0.15% Full Scale 0.5% Full Scale Tanabyte 300 0-100 sccm 0-10** lpm YesYes, 0 – 2 ppm +/- 0.5% Full Scale +/- 0.1% Full Scale 0.5% Full Scale Teledyne- API 700E 0-200 sccm 0-20 lpm4 Std.Yes, 0.1 – 10 ppm +/- 1.0% Full Scale +/- 0.2% Full Scale 0.5% Full Scale Thermo 146C 0-200 sccm 0-20 lpmNAYes+/- 1.0% Full Scale +/- 1.0% Full Scale 1.5% Full Scale * Highest optional ranges. ** Tanabyte offers a 0 – 20 lpm option

13. EPA Precursor Gas Training Workshop Calibrator Critical Features Option for multiple gas flow controllers to expand dynamic dilution range –Want to stay away from flows less than 10% or greater than 90% of MFC full scale Internal calculation of MFC flow response Programmable scheduled tasks Remote access and control ready (accept direct digital commands) Digital Inputs – controlled by remote access Digital Outputs – signals to remote device Capability to directly control solenoids without external power supplies

14. EPA Precursor Gas Training Workshop Calibrator Feature Matrix (EPA Research 2006) CalibratorProgrammable Calibrations DisplayDigital InputsDigital Outputs Ecotech 1100Yes, 20 sequences cycled through 5 points 4 line LCDRelay contact closures or TTL logic 8 digital outputs for sequence indication Environics 9100 Yes, 21 sequences (3/day) through 5 points LCDOptional RS-232 serial data interface 8 digital outputs for sequence indication Sabio 4010L 20 timer driven cal routines, user defined sequences on a 7 day calendar Bright active matrix color display 24 bit Digital Input, TTL logic levels, RS-232 24 bit output, 2 serial ports for communication Tanabyte 300 Menu operation allows auto or manual calibrations LCDTTL contact closures allows remote operation Via RS-232 300 -9600 baud Transparent pass serial I/0 after programmable pass-code is received Teledyne- API 700E Readout and control by front panel 2 line LCDVia RS-232 12 opto-isolated inputs Via RS-232 12 opto-isolated outputs Thermo 146C 10 calibration events4 line LCDRS-232 remote access

15. EPA Precursor Gas Training Workshop Certifying your Calibrator Flows Initial calibration should be provided with purchase – always recheck after delivery Certify flow controllers against a NIST traceable flow device (such as a Bios DryCal, Gilibrator or Hastings Bubble Kit or other flow device) NIST Traceable flow device should be certified annually (or if you suspect a problem) Perform quarterly or semi-annual checks of your MFCs (or until establish trend) Calculate observed flow vs set points at STP (25 degrees Celsius and 760 mm Hg)

16. EPA Precursor Gas Training Workshop MFC Calibration - Burdens Creek (1-23-2007) Environics 9100 #A50930

17. EPA Precursor Gas Training Workshop MFC Calibration - Burdens Creek (1-23-2007) Environics 9100 #A50930

18. EPA Precursor Gas Training Workshop Compressed Gas Cylinders - Features Come in variety of sizes (size 50 or 150) Recommend using Aluminum cylinders Get EPA Protocol certification from experienced vendors –http://www.epa.gov/appcdwww/pubs/600r97121/600r97121.htmhttp://www.epa.gov/appcdwww/pubs/600r97121/600r97121.htm –Note: certification periods can be shorter than expected for low concentration cylinders (next slide) Use Stainless Steel regulators and cylinder valves Use Stainless steel or Teflon lines from Regulator to MFC (Teflon recommended) Recommended Cylinder Concentrations for the NCore Sites: –SO2: 10 – 15 ppm –NO: 10 – 30 ppm –CO:200 – 300 ppm –Oxygen free - Balance Nitrogen

19. EPA Precursor Gas Training Workshop

20. Zero Air Systems - Features

21. EPA Precursor Gas Training Workshop Zero Air Source - Issues The air system should be able to provide clean air below the stated Lower Detection Limits (LDL) of the instruments you are operating at maximum required flow rates (up to 20 l/min) –NO: 50 ppt –SO2: 100 ppt –CO: 40 ppb Check the specifications before you purchase Regularly maintain/replace scrubbing materials TEI Model 111 T_API Model 701

22. EPA Precursor Gas Training Workshop Zero Air Generation - Issues Ultra Pure Cylinder Air vs. Zero Air Generators Trade off: Quantity Used vs. Costs for cylinders –High flow rates –Humidity issues –Purity of air generated –Use Ultra Pure Cylinder air to verify Generator purity (recommended)

23. EPA Precursor Gas Training Workshop Summary QC Checks and calibrations are required for NCore Monitoring Stations The MFC systems available today are compatible with the PG instruments and support a high degree of automation Calibration systems should be regularly flow certified with NIST-traceable devices Lower concentrations cylinders are required since PG instruments have lower ranges and levels of detection Gas cylinders should be certified – EPA Protocol Zero air generators should be able to “scrub” below the LDLs of the PG instruments