Last edit: 07/08/2025
Introduction: scope
This part of IEC 60079; which is a Technical Specification, provides guidance for equipment manufacturers where electrical safety devices (“SIL Rated”) are used to reduce the likelihood of potential ignition sources becoming effective in Ex Equipment located in Explosive Atmospheres.
The idea is that a Safety Device performs a safety function to control a potential ignition source present in an Ex Equipment installed in an in explosive atmospheres.
This approach of using SIL rated components to riduce the risk of an explosive athmosphere, can also be applied to a combination of elements:
- Sensor
- Logic system
- Final element
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 what the document is intended to do.
A Safety function, with basic requirements, and considered operating in low demand mode, shall respond to a potential ignition source of the EEUC (Ex-Equipment under control) before it becomes effective: in other words, an Ex Equipment which contains a potential ignition source which is controlled by a safety device.
The detection of a dangerous failure in a safety device (by diagnostic tests, proof tests or by any other means) shall result in a specified action to achieve or maintain a safe state of the EEUC