EPA 2003 Blind Audit of Protocol Gases John Schakenbach, USEPA, CAMD Scott Shanklin, Cadmus Group Bob Wright, USEPA, ORD EPRI CEM User Group Milwaukee, WI May 4-6, 2004

What is the Problem?  Historically, blind audits of calibration gases have shown poor quality initially  SO2 RATA using plant’s incorrect cal gas (low by 15%). Source could underreport SO2 by 15% and be undetected for at least 6 months.

Other Reasons Why Accurate Cal Gas is Important  Only daily assurance CEM is really working  Reference Method analyzers need accurate calibration gases to produce accurate RATA results

Purpose of Blind Audits  Help vendors improve gas quality  Help sources identify good vendors

History  1970’s EPA audited gases  Posted results –In 1995, one vendor off by -16.3% (CEM would underreport)  Strong utility and vendor support  Auditing strongly correlated with improved gas quality

Current Gas Analysis  First audit in 7 years  Blind audit  14 national gas vendors  Similar procedures as in past  SRMs and NTRMs used  42 Protocol tri-blend cylinders  MACTEC (UV and NDIR) and Spectral Insights (FTIR)

Tri-blend Protocol Gases

Instrumentation  NO - API Model 200AH chemiluminescence  NO - AMETEK Model 922M differential absorption UV  SO2 - Bovar Model 721M differential absorption UV  CO2 - California Analytical Model 3300A NDIR  NO, SO2 and CO2 - Nicolet Nexus Model 760 FTIR  Environics (Graseby-Nutech) Series 3740 gas dilution system

Candidate, Zero, SRM or NTRM Gas Standards FTIR Spectrometer Cell Vacuum Pump Selector Valve Isolation Valves Vent P T Computer Transducers Check Valves Toggle Valves Vent Gas Manifold/Regulator Manifold Vent Valve Vent Spectral Insights Assay Apparatus

Accuracy Criterion  Part 75, Appendix A, sec requires 2.0% of tag value  Protocol procedures achieve +2% of tag value: 1% Standard Reference Material plus 1% EPA Protocol methodology

Problems  CO2 quenching biased the NO concs from chemiluminescent analyzer low –Chemiluminescent NO concs thrown out –Measurements repeated with a UV analyzer  UV analyzer was set up for ppm NO, but should have been for ppm –Threw out high level NO concs –Repeated high level NO measurements using FTIR

Problems  SO2 interfered with UV analyzer NO readings –Injected SO2 in N2 to develop a correction  Ran out of high level CO2 SRM for FTIR –Threw out the high level CO2 FTIR results and relied on NDIR

Results  EPA presents the following information without assigning a rating to the gas vendors.  If EPA’s and vendor’s values differ by 2.0% or less, then because of uncertainties in the measurement system, statistically, there is no difference between the two values, e.g., a difference of 2.0% and 0.5% are considered equal.  All vendors that failed are re-analyzing their gas cylinders. When EPA receives the re-analyzed results, they will be posted.

Results  Overall failure rate: 14 of 126 analyses (11%)  57% of vendors failed  SO2: Worst tag value ~2.5% high  NO: Worst tag value ~8% low  CO2: Worst tag value ~4.9% high  All 42 cylinders met the Protocol Procedure documentation requirements

/140/143/140/ / High 0/141/140/14 2/143/142/14Mid 1/14 6/144/14 6/14Low BothFTIR NDIR BothFTIRUVBothFTIRUV CO 2 AnalysesSO 2 AnalysesNO Analyses EPA Protocol Gases not meeting Acceptance Criterion

Percent Failure Rate by Vendor Technology

Lessons Learned  Detailed standard operating procedures for analyzing single and multicomponent mixtures are needed in EPA’s Protocol Procedures, especially for FTIR  First ensure lab can correctly analyze single component cylinders  Then check for interferences by measuring a multicomponent cylinder simultaneously with analyzers for each component gas  Use an SRM or NTRM to get reference spectrum for FTIR measurements

Audits Can Be Effective

Audit Program Issues  Scope  Stringency  Structure

Options - Scope  Part 75 only  All source-level programs, e.g., Part 75, NSPS, SIP, NSR  All source and ambient-level programs

Options - Stringency  Work with vendors to fix problems  Work with vendors and post audit results on web sites  Formal gas vendor certification program

Options - Structure  Spin-off to 3rd party (A2LA, NVLAP, NSF, etc.) to purchase and analyze cylinders (set up fee-based system) with EPA oversight  Through EPA task order, contractor purchases and analyzes cylinders from major suppliers (EPA used to do this)  Other (NELAC, gas vendor-developed mechanism, NIST, EPA lab, etc.)

Initial Recommendations Scope All source and ambient-level programs Stringency Work with vendors; post audit results Structure Set up fee-based system to purchase and analyze cylinders using 3rd party with EPA oversight; or possibly use gas vendor-developed mechanism

Example 3rd Parties for Spin Off  American Association for Laboratory Accreditation (A2LA)  National Voluntary Laboratory Accreditation Program (NVLAP)  National Sanitation Foundation (NSF)

Next Steps  Get more feedback from gas vendors and other interested parties

For a Copy of Presentation click on “Recent Additions” near top left corner or John Schakenbach Phone: