(65d) Oleum Spill Tests - Field Data for Model Validation

Oleums are mixtures of sulfur trioxide in sulfuric acid and are produced in several strengths. They are used as sulfonating agents in many applications. When accidentally released from vessels or pipes oleum reacts instantaneously with water available from all sources like atmosphere, concrete, soil, etc., to form a fine acid mist that disperses downwind, based on atmospheric conditions. Unlike most other chemicals, the vaporization of sulfur trioxide from oleum spills depends not just on its partial pressure but a variety of conditions. Complex chemical reaction and heat generation that occur in the liquid phase determine the amount of sulfur trioxide released above a pool of liquid. The sulfur trioxide then reacts instantaneously with the moisture in the atmosphere generating sulfuric acid and a lot of heat. Water and/or foam are used effectively in mitigating oleum spills. However, very limited laboratory or field data are currently available that describe the complex behavior of oleums. Several theoretical models have been developed to predict the vaporization and dispersion of the chemical upon loss of containment. These models and methods have not been validated. In this paper, details will be provided on a field test conducted in Nevada in 2003 & 2006 for spills of 65% oleum. Included will be a description of the spill mitigation, field measurement methods, and some preliminary results.