While working on a project for a tolling manufacturer that uses a single piece of process equipment for numerous chemicals, we realized the need to determine the worst-case chemical for each relief scenario. Since each relief device can see dozens of chemicals, we needed a method to determine which chemical will require the largest Pressure Relief Device (PRD). For Pressure Relief Valves (PRVs), we needed to determine which chemical will require the largest orifice and have the largest pressure drop.
This article details a few ways to quickly determine which chemical will require the largest orifice area and/or pressure drop when large number of chemicals are used in a process, so that the engineer can narrow down which chemicals require more detailed orifice area calculations.