The calculation of plume rise and air dispersion model predictions of ground-level concentrations from a flare are based on the user inputs of source pseudo-stack height, pseudo-diameter, pseudo-temperature and pseudo-velocity. Regulatory jurisdictions across Canada, the United States and around the world have adopted approaches for flare pseudo-parameters that include some but not all of the inseparable interrelationships between the buoyancy flux, momentum flux and stack tip downwash. We expose the consequences of arbitrary deviation for the sake of apparent simplicity. The approaches for flare modelling used by the regulators in Alberta, British Columbia, Ontario and the United States are compared. The simplifying assumptions used by others and the breaking of the fundamental interrelations can be described as pseudo-science. The consequences are demonstrated using screening modelling predictions for an example flare. Over-prediction and under-prediction for each approach are discussed. What are the consequences of continuing to model flare source parameters using overly simplified approaches? First, the regulators perpetuate the myths that the flare source height, temperature, diameter and velocity are constant for all wind speeds and ambient temperatures. Second, that it is acceptable to make simplifying assumptions that violate the conservation of momentum and energy principles for the sake of convenience. Finally, regulatory decisions based on simplified source modelling results in predictions that are neither conservative nor realistic and cannot be relied upon for human health, safety or environmental assessments. EPA should modify the dispersion models to include a flare source input option using the science presented in this paper.
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