There is a great deal of confusion surrounding the requirements for electrical equipment which is in direct contact with the process, specifically; is a Secondary Seal required? Does my device require the “Single Seal” or “Dual Seal” markings? Are there other options? etc. I’ll try to answer some of these questions. A Process Seal is a device to prevent the migration of process fluids from the designed containment into the external electrical system. Electrical equipment with an interface in direct contact with process fluids under pressure must incorporate a “process seal” to prevent migration of the flammable fluid into the wiring system. The Canadian Electrical Code (2012), Rule 18-072 and the National Electrical Code (2011), Rules 501.17 and 505.26, both contain requirements, which to paraphrase, state, “Process-connected electrical equipment that incorporates a single process seal such as; a single compression seal, diaphragm, or tube to prevent flammable or combustible fluids from entering a conduit or cable system capable of transmitting fluids, shall be provided with additional means to mitigate a single process seal failure”.