Which statement best describes the factors used to specify a source model?

Which statement best describes the factors used to specify a source model?

• A. Temperature and pressure
• B. Release duration and wind speed
• C. Aperture and material phase
• D. Vessel age and maintenance

Answer: (C)

A source model is defined by how the material leaves the vessel—the release geometry and the state of the material at release. The opening through which the material escapes, the aperture, directly determines the mass flow rate and initial jet characteristics. The material phase tells you whether the released material is a gas, vapor, liquid, or aerosol, which sets the initial conditions for the plume, such as density, vapor pressure, and how evaporation or condensation may occur. Temperature and pressure describe conditions that influence the material's state but don’t specify how the release happens. Release duration and wind speed pertain to what happens after release, i.e., dispersion dynamics, not how the source is defined. Vessel age and maintenance relate to equipment history rather than the immediate release terms. So aperture and material phase are the factors that best specify the source model.

A source model is defined by how the material leaves the vessel—the release geometry and the state of the material at release. The opening through which the material escapes, the aperture, directly determines the mass flow rate and initial jet characteristics. The material phase tells you whether the released material is a gas, vapor, liquid, or aerosol, which sets the initial conditions for the plume, such as density, vapor pressure, and how evaporation or condensation may occur. Temperature and pressure describe conditions that influence the material's state but don’t specify how the release happens. Release duration and wind speed pertain to what happens after release, i.e., dispersion dynamics, not how the source is defined. Vessel age and maintenance relate to equipment history rather than the immediate release terms. So aperture and material phase are the factors that best specify the source model.