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4135 Bluebonnet Dr. Stafford, TX 77477 1-877-864-7710 www.factorydirectsafety.com
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Photoionization Detectors for Industrial Hygiene in the Oil & Gas Industry Werner Haag, Ph.D. Brent Yaschuk Factory Direct Safety & Environmental, Inc.
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PID Standard Features: Measure many organic vapors Measure many organic vapors & some inorganics 10.0 eV, 10.6 eV, & 11.7 eV Lamps 10.0 eV, 10.6 eV, & 11.7 eV Lamps Non-specific: Need to know gas being measured to quantify Non-specific: Need to know gas being measured to quantify Datalogging Datalogging TWA & STEL Recording TWA & STEL Recording Fast response (<3 seconds) Fast response (<3 seconds) Continuous read-out Continuous read-out
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PID Chemical Response Compound ClassRelative Sensitivity Aromatics (e.g., Benzene, Pyridine)++++ Alkyl Iodides, Bromides, Chlorides++++, +++, + Double Bonded Compounds+++ Organic Amines+++ Sulfides & Mercaptans+++ Ketones, Ethers & Silicates+++ Alkanes, Esters, Alcohols, Aldehydes++ H 2 S, NH 3 & PH 3 + to ++ H 2, CO, CO 2, O 2, N 2, HCN, SO 2, Acids-
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PID Applications: Oil Refineries Hydrocarbons
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PID Applications: Oil/Chemical Tankers Diesel Fuel, HCs, Solvents, NH 3, etc. Confined Space Entry
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PID Applications: Heat Exchangers Dowtherm: Diphenyl oxide / Biphenyl OSHA PEL for mix = 0.5 ppm
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PID Applications: Fugitive Emissions Testing - EPA Method 21
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PID Applications: Hazmat Response Various Chemicals
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PID Applications: Soil Remediation Screening & Leaking Underground Storage Tanks Various Chemicals
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PID Applications: Natural Gas Dehydrator Re-boilers & Compressor Condensate (Benzene)
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PID Applications: Fenceline Monitoring
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PID Applications: Indoor Air Quality ppb Level TVOC & Locating Odor Sources
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PID Applications: Space Shuttle Tanks Hydrazine Fuel Decontamination
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Modern PIDs Recent Improvements: Sensitivity to low ppb levels Sensitivity to low ppb levels 450 Chemical Response Factors 450 Chemical Response Factors Improved Linearity: ppb to 10,000 ppm Improved Linearity: ppb to 10,000 ppm Humidity Effects Almost Eliminated Humidity Effects Almost Eliminated Reduced Methane Interference Reduced Methane Interference 30-hour Li-Ion Battery 30-hour Li-Ion Battery
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Improvements Accomplished by: Shorter cell path length to improve linearity & reduce interference, requires precise manufacturing & strong lamps Shorter cell path length to improve linearity & reduce interference, requires precise manufacturing & strong lamps “Fence” Electrode removes Leak Current “Fence” Electrode removes Leak Current Proprietary Anti-contamination Technology Proprietary Anti-contamination Technology
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Water Vapor Effects 1) Reduced response of Organic Vapors due to competitive light absorption & chemical quenching
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Water Vapor Effects 2) “Leak” Current at high humidities when sensor is not ultra-clean “Fence”
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FENCE ELECTRODE PREVENTS LEAK CURRENT IN HIGH HUMIDITY
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Benzene in Gasoline Typically 0.5-2%: Difficult to measure selectively
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Benzene in Fuels Exposure Limits for Various Fuels ChemicalACGIH TWA Benzene0.5 ppm Diesel Fuel12 ppm Jet Fuel30 ppm Gasoline300 ppm
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Benzene in Fuels Mixture TWA Calculation TWA total = ______________1 f benzene f gasoline + TWA benz ____________ TWA gas.
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Benzene in Gasoline Typically 0.5-2%: Difficult to measure selectively
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Benzene in Fuels Exposure Limits for Various Fuels ChemicalACGIH TWA Benzene0.5 ppm Diesel Fuel12 ppm Jet Fuel30 ppm Gasoline300 ppm
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Benzene Specific Measurement Methods with DL near 0.5 ppm MethodTimeDLCostOther Tubes10-20 min0.5 ppm¢ Automated Tubes (Draeger CMS) 10 min0.2 ppm¢¢ PID w/Filter Tube1-3 min0.02 ppm$ Portable GC5-10 min0.1 ppm$$Bulky Portable IR<1 min2 ppm$$$Heavy GAC or Gas Bag + Lab Analysis 1 week0.01 ppm$$$$Off-site
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Tiger Select PID/Tube can measure Continuous ppb Levels Total Aromatic Compounds (TAC) Benzene Specific readings – Single Point and 15- minute STEL
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Total Aromatic Compounds Mode Uses 10.0 eV lamp Applies the Benzene response factor (0.5) Responds predominantly to aromatics Continuous readings with ~5 ppb resolution If a reading over 0.5 ppm is seen, insert a tube and make a Benzene specific measurment ChemicalI. E.R.F. Benzene9.25 eV0.55 Toluene8.82 eV0.54 o-Xylene8.56 eV0.56 n-Hexane10.13 eV- n-Octane9.82 eV13
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Benzene Tube Specificity No Effect of: 400 ppm Toluene 200 ppm o-Xylene 300 ppm Octane 25 ppm H 2 S ● 100% Methane
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Benzene STEL measurements Continuous benzene readings and/or STEL measurements can be made until the color change proceeds up to the 3/4 length mark indicated on the tube Response will lag actual concentrations by a minute or two
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Benzene Standard – Humidity Test (Filter Tube absorbs moisture) Tube #Relative Humidity PID/Tube Response 1Dry5.0 ppm 2Dry4.9 ppm 3100 %5.1 ppm 4100 %4.8 ppm
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Benzene in Refinery Samples Sample Lab GC/FID (mole %) PID/Tube (mole %) 87 Octane Gasoline0.86 %0.63 % Reformer Feed1.2 %1.0 % Reformer Product6.3 %7.2 % Benzene Light Ends22 %24 %
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Benzene Field Comparison ± Standard Deviation As % of Lab Value ± Standard Deviation SamplePID/Tube Portable GC/FID Draeger CMS Standards 1) 101 ± 16%116 ± 23%120 ± 52% Field Samples 2) 97 ± 29%84 ± 21%103 ± 92% 1) Avg of 24 Standards, including BTEX mixtures 2) Avg of 18 different field measurements
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Stafford, Texas 1-877-864-7710 Thank you
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