Consequence Modelling

One of the most critical components to accurately assessing the risk in a PHA is understanding the severity of the consequences. So what do you do when you don’t know? Toxicity and atmospheric dispersion of toxic or flammable gases is a critical consideration when assessing the consequences of a release.

Sometimes during a PHA it can be difficult to determine if a release will result in a minor reportable environmental event or a large vapour cloud which could lead to an explosion. Consequence modelling helps address this issue by providing the confidence you need to make a more informed decision.

Major Benefits

  • Understand the consequences of an inadvertent release with quantitative results

  • Ensure appropriate safeguards are in place to protect personnel, the environment, and facilities against potential releases

  • Optimize design decisions such as vent heights, gas detection placement, or requirements to tie relief valves into a flare system

Scenarios where consequence modelling may be useful

  • Understanding the dispersion of a toxic gas cloud due to a release

  • Evaluating the accumulation of flammable gas due to a release

  • Quantifying the impacts of a fire or explosion

  • Visualizing the extent of a pool fire caused by a release

  • Using quantitative data to make decisions for critical scenarios

Cloud height vs distance for a leak of toxic gas from a height of 5.5 m at various weather conditions

Concentration vs distance from the leak for a release of toxic gas from a pipe at various weather conditions

Dispersion modelling can be used to determine the concentration of a specific chemical of interest at different heights and distances from the release.  This information can then be used to determine if there is potential to reach a critical concentration near an ignition source or if there is potential for personnel exposure to a toxic gas. This can then be used to make decisions regarding considerations such as vent stack height or the requirement to tie a pressure relief valve into a flare or vent system. Expected thermal radiation due to a fire or overpressure due to an explosion can also be assessed.