Last edit: 07/08/2025
General requirements
When we are using a safety device, the potential ignition source that has to be controlled, needs to be taken into account.
The safety function of the device shall be determined, and the device needs to be designed to provide the safety function reliably under the specified range of operating conditions; during commissioning, the number of accessible parameters shall be minimized and locked after parameterisation by using codes, passwords, a jumper or a switch.
The device needs to be protected against external interference like EMC and needs to have some sort of level of cyber security.
Specification of the safety function
If requested, by certain circumstances, the safety function shall bring the EEUC into a safe state.
The activation threshold of the parameters that need to be controlled, to prevent ignition, shall be specified for the ignition hazard in the instructions, by also taking into account all the relevant safety parameters named after the ICE 60079 series and the ISO 80079 series.
Requirements for achieving the safety integrity – Simple safety devices
Safety devices are divided in two main groups according to the type of requirements and protection they can sustain.
A safety device can be regarded as a simple safety device if the components required to achieve the safety function meet the following requirements:
- The failure modes of all constituent components are well defined
- The behaviour of the element under fault conditions can be completely determined
- There is sufficient dependable failure data to show that the claimed rates of failure for detected and undetected dangerous failure are met.
A simple safety device can be assessed according to its dangerous hardware failure rate in an FMEA, according to Annex A.
A systematic capability assesment should be provided, however, if the systematic capability was not assessed a justification shall be documented.
Requirements for achieving the safety integrity – Complex safety devices
All the safety devices not covered in the description above, as simple devices, needs to be classified as complex safety devices; the devices that are part of the category od complex safety devices hall be designed to comply with an applicable functional safety standard.