Layer Of Protection Analysis (LOPA) applied to Ammonia Refrigeration Systems

Ammonia is a common refrigerant in the industry. It has excellent thermodynamics and thermo physics properties but it is flammable and toxic. Even though the refrigeration system is simple, when released refrigerant ammonia has caused injuries and fatalities.
Layer of Protection Analysis (LOPA) is a semi-quantitative risk assessment technique. This methodology defines a cause-consequence scenario and estimates the likelihood of the undesired consequence from occurring. LOPA helps to determine if the risk has been successfully mitigated with an adequate number of Independent Protection Layers (IPLs).

This research applies LOPA using the framework for an expert system developed by Markowski, and Mannan. In addition, fuzzy logic is used to evaluate the initiating event frequency, the probability of failure in demand for the IPLs and the risk for the scenarios.
The main tasks to accomplish are development of incident Scenarios, evaluation of severity of consequences, identification of the layers of protection for ammonia refrigeration systems, and risk estimation for the scenarios.

The final goal is to obtain a framework that simplifies the application of the LOPA technique to Ammonia Refrigeration Systems.