LAUSR

Abstract Process hazard analysis (PHA) teams are responsible for determining and categorizing the potential impact of a loss of containment. For streams containing hydrogen sulfide (H₂S), the health and safety consequences of a worker being exposed to H₂S are a function of airborne concentration in the breathing zone and duration of exposure. PHA teams often do not have the technical knowledge to link the known concentration of H₂S in the process stream to an adverse health outcome. This paper describes the methodology and the assumptions made in developing such guidance. H2S concentration in the process stream was correlated to concentration of H2S in the breathing zone. Dispersion modeling was used to assess vapor releases, while additional multi-phase release modeling was required to estimate the amount of H2S liberated from the released liquid. Modeling was completed for different H2S concentrations in process streams under a variety of conditions. Breathing zone concentrations were assessed against published occupational exposure levels associated with probable health outcomes. This study demonstrated that H2S stream concentrations can be associated directly with a consequence categorization that can be used in a PHA. Results were summarized, providing simplified guidance that is valid over a wide range of process conditions and release scenarios.