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      What is Isokinetic Sampling?

      The Isokinetic Sampling Theory

      What is isokinetic sampling?
        • Iso = Uniform, same, equal, or similar
        • Kinetic = Pertaining to motion
      • Uniform sampling of particles and gases in motion within a stack
      • Why is isokinetic sampling carried out?
        • To provide an unbiased, representative assessment of the quantity of particulate matter emitted from a source, stack, or vent.
      Simplified Isokinetic Rate Equation
      • ΔH = K x Δp
      • The relationship between vs and vn is the core understanding of isokinetic sampling
      • Reading Δp from the pitot tube and setting the proper ΔH (based on stack conditions and K-factor) on the meter box allows the operator to sample isokinetically

      Basic Terminology

      • Pmrs = Cs x Qs
      • Concentration (Cs)
        • Quantity of pollutant per volume of effluent gas (grams/cubic meter)
      • Stack gas flow rate (Qs)
        • Volume of effluent gas per length of time (cubic meters/hour)
      • Pollutant mass rate equation (Pmrs)
        • Volume of pollutant gas per length of time (grams/hour)

      Isokinetic Sampling and Bias

      • To obtain average pollutant concentration, these parameters are needed:
        • Quantity of mass emitted from stack
        • Total quantity of volume from stack
      • Isokinetic sampling provides best approach for accurate data
      • Pollutant mass rate (pmr)
        • pmra (Ratio-of-areas: An ratio As)
        • pmrc (Ratio-of-concentration: mn ratio An)

      Monitoring Stack Emissions

      • Government and industry-oriented purposes:
        • Assessment of current performance (compliance)
        • Optimization of plant performance
        • Choice of abatement techniques (scrubbers, baghouses, etc.)
        • Validation of abatement equipment performance
        • Assessing regulatory requirements (setting emission limits)
        • Providing data for health risk assessments

      Isokinetic Sampling:
      Application of 5
      US EPA Sampling Methods

      • Method 1 – Sample and Velocity Traverses from Stationary Sources
      • Method 2 – Determination of Stack Gas Velocity and Volumetric Flow Rate
      • Method 3 – Gas Analysis for Carbon Dioxide, Oxygen, Excess Air, and Dry Molecular Weight
      • Method 4 – Determination of Moisture Content in Stack Gases
      • Method 5 – Determination of Particulate Emissions from Stationary Sources

      For more information, please refer to our Isokinetic Presentation or the EPA's website. Additionally, we have an Intro to Isokinetic Sampling video on our YouTube channel.