DIN IEC/TS 60079-42:2017-03 - Draft

Safety devices that monitor potential ignition sources and act as part of the protective devices for equipment operating in potentially explosive atmospheres should be reliable for the intended use in order to comply with both the principles of hazardous area classification and other types of explosion protection. This document provides guidance on the level of reliability to be achieved by the safety functions used for equipment as part of the DIN EN 60079 (VDE 0170) series of standards. It provides guidance to equipment manufacturers where an electrical safety device is used to reduce the likelihood of a potential ignition source becoming effective on equipment used in potentially explosive atmospheres. Electrical safety devices can monitor potential ignition sources of both electrical and non-electrical equipment in explosive atmospheres. The electrical safety device performs a safety function with regard to the risk of ignition. The safety device can be a combination of several safety elements, such as: - sensor - logic unit - actuator. Increasing the equipment protection level (EPL) of a device is not within the scope of this document. This Technical Specification does not apply to: - mechanical control equipment such as pressure relief valves, mechanical governors and other mechanical safety devices - the use of gas detection - control equipment to prevent the occurrence of explosive atmospheres, such as inerting systems and ventilation systems - mitigation of an explosion. Some potential ignition sources cannot be monitored by a safety device. Electrical safety devices for which the level of safety integrity is given in other parts of the IEC 60079 series of standards do not fall within the scope of this Technical Specification. A safety device can be a measure to achieve a required EPL of the Ex Equipment with respect to a potential ignition source. Electrical safety devices may be installed either as part of or separate to the Ex Equipment under control (EEUC) and may be located inside or outside the hazardous area. The responsible Committee is DKE/K 241 "Schlagwetter- und explosionsgeschützte elektrische Betriebsmittel" ("Electrical apparatus for potentially explosive atmospheres") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.