Assessing the inherent safety of substances: Precursors of hazardous products in the loss of control of chemical systems

A procedure for the assessment of the hazard due to the possible formation of dangerous substances as a consequence of the loss of control of a chemical process was developed. The procedure was based on the integration of specifically developed tools and on reference experimental protocols to obtain reliable and reproducible reference data on the products that may be formed in the loss of control of an industrial chemical process. The screening procedure developed proved to be an effective methodology to integrate the information reported on MSDS concerning the expected decomposition products. The application to different case-studies evidenced that the hazard profile of a substance may be heavily influenced by the products formed as a consequence of thermal degradation or combustion conditions. The results obtained clearly show that a correct and complete assessment of the inherent safety of a substance also requires to take into account the hazard coming from the decomposition products that may be formed as a consequence of anomalous operating conditions. The analysis of this aspect is a key issue for the correct application of the substitution principle in inherent safety process development.