How many PHEL curves are used at one time?

The number of PHEL curves used at one time is one, which allows for clear focus and interpretation of the specific parameters related to a single curve. Each PHEL (Process Hazard Evaluation and Lifecycle) curve represents distinct information and risk profiles related to different engineering scenarios. Using one curve at a time ensures that the analysis remains detailed and accurate, preventing the confusion that could arise from overlaying multiple sets of data or parameters.

Using more than one curve simultaneously could lead to misinterpretations or oversight of key details, as the intricacies of each curve may not be fully appreciated or properly evaluated. This approach emphasizes the importance of thoroughness and clarity in engineering evaluations, which is crucial in maintaining safety and effectiveness in engineering practices.