Everyone once in a while we come across purged and pressurized enclosures during our PSM/RMP audits involving processes that contain/process flammable liquids or gases. These purged and pressurized enclosures are used in lieu of using enclosures that are either intrinsically safe or explosion proof. But this method of protecting the process from ignition sources is NOT as simple as some would hope; in fact the method comes with its very own Recognized and Generally Accepted Good Engineering Practice (RAGAGEP), NFPA 496: Standard for Purged and Pressurized Enclosures for Electrical Equipment. Here are some requirements that may be a surprise to some: