THE ONDEK VAPOR DISPERSION MODEL

During bulk liquid cargo loading of chemicals and petrochemical products, vapors are released at or above deck level by the displacement of the ullage atmosphere in an empty tank. These vapors mix with the air and begin to spread out from the discharge point, becoming more dilute as they move downward. The relative vapor hazards on deck can be determined by estimating the size of the cargo vapor contour at a given concentration over the deck area of the vessel. ONDEK is a computer program designed to compute estimated vapor concentrations and superimpose a plot of the computed contour over a schematic outline of the vessel.