Air Quality

Emission Isolation Flux Chamber

The Emission Isolation Flux Chamber is a USEPA referenced method for determining mass emission rates from land or liquid area sources such as an open tank, a storage pile, a lagoon, or a surface contamination.


The Emission Isolation Flux Chamber is typically constructed with a plexiglass dome mounted to a stainless steel base. Ports in the plexiglass cover provide access for sweep air inlet and outlet ports, as well as temperature measurements. Since the chamber is inserted below or subsurface, the sampling area is effectively "isolated" from external influences.


The Emission Isolation Flux Chamber is a versatile tool for measuring the emission rate of volatiles from a wide variety of sources:

  • Waste treatment and disposal facilities
  • Landfills
  • Land farms
  • Wastewater treatment facilities
  • Industrial solvent treatment
  • Surface spills
  • Industrial processes
  • Subsurface groundwater contaminants
  • Theory of Operation

    The flux chamber is a dynamic mixed tank reactor. The volume of the chamber (30 liters) and the sweep air flow rate of 5 liters per minute determines the residence time of the standard chamber to be 6 minutes. After 5 residence times (30 minutes), the contents of the chamber are at equilibrium and grab and/or integrated samples can be collected.

    The flux is calculated by knowing the volume of the chamber (30 liters or 0.030 m3), the sweep air flow rate (5 liters per minute), the surface area of the chamber (0.13 m2), and the concentration of the compound of interest.

    • Flux = (CxF)/A
    • C = Concentration in mg/m3
    • F = Sweep Air Flow in m3/min/(Surface Area, 0.13m2)
    • A = Area of the chamber in m2

    Detection Capabilities

    • Total Volatile Organic Compounds
    • Individual Toxic Organic Compounds
    • Semi-Volatile Organic Compounds
    • Greenhouse Gases (i.e., methane, carbon dioxide, and nitrous oxide)
    • Odor-causing compounds (hydrogen sulfide, mercaptans, thiophenes, or ammonia)
    • Radioactive compounds such as radon


    Problems - Land and Sea

    Suppose you need to determine the emission rate of pollutants from a wastewater lagoon or a land farm located on your facility. How do you do it? At first you might consider measuring the concentration of the air above the surface or perhaps analyzing a sample of the soil or liquid, but neither method provides you with a mass emission rate. You might also consider modeling or some form of transect monitoring. But these are both expensive, time-consuming approaches and may not provide representative data. However, the emission isolation flux chamber is a proven methodology for directly determining mass emission rates from area sources.

    Solutions - Land and Sea


    The flux chamber can be used on any land-based area source emitting air emissions, including landfills, land farms, and stockpiled materials. When testing on land, the chamber is generally sealed by inserting it into the surface to a depth of approximately 1/4-inch.


    Air emissions from liquid surfaces such as open tanks, surface spills, lagoons, storage ponds, waste treatment facilities, dissolved air flotation tanks, treatment units and discharge points, can be measured most efficiently by suspending the chamber from an overhead structure so as to control the placement and depth of the chamber into the liquid (water, wastewater, or petroleum).

    Downhole Flux Chamber

    The downhole flux chamber technique investigates subsurface contamination including spills, contaminated groundwater, underground plume detection and plume migration mapping. The downhole assessment flux chamber is a small (0.6 liter) acrylic chamber that is designed to fit into a hollow stem auger. With it, flux can be determined as a function of depth. Data from the downhole flux chamber can provide diagnostic information useful for a variety of purposes, including subsurface plume identification, source apportionment, support for engineering analysis, and Phase 3 site assessment.

    More About the Isolation Flux Chamber:

Emission Isolation Flux Chamber Key Points:

The only EPA-recommended direct assessment technology for area source emission assessment

Well-established, mature technology

Allows selective sampling with low-detection capability

Testing can be conducted free of upwind interferences

Data results provided in the engineering units favored for modeling inputs and reporting


Fig A. The Emission Isolation Flux Chamber


Fig B. Determining Emissions from Wastewater Treatment Sludge


Fig C. Dairy Farm Emissions


Fig D. Measuring Emissions from a Refinery Aerated Lagoon


Fig E. Compost Testing


Fig F. Multiple Flux Chambers


Fig G. Municipal Wastewater Treatment


Fig H. Downhole Flux Chamber schematic

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