Hydrazine and Aqueous Hydrazine Solutions: Evaluating Safety in Chemical Processes

This contribution provides a summary of the hazards of hydrazine and its aqueous solutions and an understanding of the important role dilution plays in increasing the inherent safety of aqueous hydrazine solutions. Rather than provide an extensive description of the hazardous properties of hydrazine, the intent is to provide enough information to allow the reader to decide if hydrazine may be acceptable for a given application, and if so, what concentration range may provide an acceptable safety and environmental risk. Calculations are used to explore the favorable effect of dilution on the risk of fire, explosions, runaway reactions, and toxic exposure. Examples are provided to illustrate the strong effect catalysts can have on decomposition reactions. An analysis indicates the previously published lower flammability limit (LFL) is nonconservative.