IEC TS 60079-42:2019

A safety device can be a measure to achieve a required EPL of the Ex Equipment with respect to a potential ignition source. The combination of the safety device and the Ex Equipment could then comply with the relevant standards of the IEC 60079 series and the ISO 80079 series with respect to the Equipment Protection Level. However, increasing the EPL of Ex Equipment by the simple addition of a safety device is not within the scope of this Technical Specification.
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, e.g. inerting systems and ventilation systems
• mitigation of an explosion