Correction factors basics
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Correction factors basics

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    Correction factors basics Correction factors basics Presentation Transcript

    • Correction Factors LEL & PID Paul Tarter Regional Sales Manager RAE Systems
    • What is a Correction Factor?
      • Correction Factor (CF) is a measure of the sensitivity of the LEL/PID sensor to a specific gas
      • CFs are scaling factors, they do not make a LEL/PID sensor specific to a chemical, they only correct the scale to that chemical.
      • Correction Factors allow PID calibration on cheap, non-toxic “surrogate” gas .
      • Ref: RAE handout TN-106/TN-156
    • Catalytic LEL Sensor Response
      • When a LEL monitor is calibrated to a gas (i.e. methane) it always thinks it is seeing methane.
      • Like a truck that is designed to use a specific size of tire
      • That size tire is calibrated to the speedometer.
    • Catalytic LEL Sensor Response
      • If your monitor calibrated for methane is exposed to gasoline
      • It would be like putting a different size tire on that truck and not adjusting the speedometer.
      • It will still show a speed, but it will not be accurate
    • LEL Correction Factors
      • LEL Correction Factors
        • Acetone 2.2 CF
        • Ethanol 1.7 CF
        • Gasoline 2.1 CF
        • Jet Fuel JP-4,-5,-8 3.4 CF
        • Propane 1.6 CF
        • (RAE Systems TN-156)
    • PID Correction Factors 8 9 10 11 12 13 14 15 8.4 9.24 9.54 9.99 10.1 10.5 10.66 11.32 11.47 12.1 14.01 Benzene MEK IPA Ethylene Acetic Acid Methylene chloride Carbon Tet. Carbon Monoxide Styrene Oxygen Ionization Potential (eV) 11.7 eV Lamp 10.6 eV Lamp Not Ionizable 9.8 eV Lamp
    • CF Example: Toluene
      • Toluene CF with 10.6eV lamp is 0.5 so PID is very sensitive to Toluene
      • If PID reads 100 ppm of isobutylene units in a Toluene atmosphere
      • Then the actual concentration is 50 ppm Toluene units
      • 0.5CF x 100 ppm iso = 50 ppm toluene
    •  
    • Question?