Design considerations for pressurized enclosures with containment systems according to the second edition of EN 50016

The second edition of EN 50016 introduces new concepts to cover the safety aspects associated with the explosion protection of electrical equipment which is intended to handle flammable substances in normal operation and which cannot be readily protected by other explosion protection. The definitions to clarify these concepts are briefly discussed. The authors deal with ignition capable apparatus, protected from an external flammable hazard, by being enclosed in a pressurized enclosure into which, for operational reasons, a flammable substance is introduced. The authors discuss the release conditions, the design requirements for the containment system, protective gas and pressurising technique, internal hot surfaces, enclosure testing, and the pressurisation test system