PD IEC TS 60079-42:2019

Explosive atmospheres. Electrical Safety Devices for the control of potential ignition sources from Ex-Equipment | Status: Current, Work in hand

1 Scope This part of IEC 60079, which is a Technical Specification, provides guidance for equipment manufacturers where electrical safety devices are used to reduce the likelihood of potential ignition sources becoming effective in Ex Equipment located in Explosive Atmospheres. Electrical safety devices perform a safety function to control potential ignition sources from both, electrical or non-electrical Ex Equipment in explosive atmospheres. This document may also be applied to a combination of elements performing a safety function. For example:

• • Sensor
• • Logic system
• • Final element

This Technical Specification can also be used for assessing the safety device independently, without being designed for a specific Ex Equipment. 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 document. This document 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

NOTE Some potential ignition sources might not be practicably controlled by safety devices.

Electrical safety devices, where the level of safety integrity is identified under other parts of the IEC 60079 series, this document can be used as a reference for the realization of the level of safety integrity. 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.