Impact of external influences on the ex equipment choice and technical answers from standards

Ex electrical equipment intended to be used in explosive atmospheres shall be selected and/or installed so that it is protected against external influences which could adversely affect the explosion protection (e.g. pressure conditions, chemical, mechanical, vibratory, thermal, electrical, humidity, corrosion). External influences shall be identified as part of the installation design and selection of equipment for the installation and measures applied for control shall be documented and included in the explosion protection document. Petrochemical plants are often submitted to several heavy conditions due to external influences. We would like to highlight that Ex standards including installation and maintenance codes give complete or partial answers in order to guarantee the suitability of Ex equipment with these specific conditions.