Needed a functional safety expertise in support of “fine tuning” IEC-60079-42 (TC31 WG42) Explosive atmospheres - Part 42: Electrical safety devices for the control of potential ignition sources for Ex-Equipment in addition to the request going out today within the S84 committee proper.
Below is the introduction verbiage for the Standard.
Generally, the probability of potential ignition sources becoming effective is mitigated by applying the protection measures according to the IEC 60079 and the ISO 80079 series. If the probability of an ignition source becoming effective and none of the aforementioned protection measures can be applied, this probability could be reduced by using a suitable safety device. 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.
Safety devices, which are used as part of the protection of Ex Equipment for control of potential ignition sources, should consider reliability for the intended purpose to recognise the principles for the classification of hazardous areas and explosion protection techniques. This document provides requirements for the application of safety functions to provide a reduction of ignition risk for Ex Equipment as part of the IEC 60079 series and ISO 80079 series. It relies on relevant IEC and ISO standards for safety related control systems. However, some of the Functional Safety concepts can’t be related directly to the Hazardous Area classification.
This document does not specify the standard that will be used for the assessment of the integrity of the safety function (for example, IEC 61508, IEC 61511, IEC 62061 or ISO 13849-1/2) to give the manufacturer of the equipment and the safety device the opportunity to choose the relevant standard. The main requirements are based on risk reduction factors. This addresses the plurality of safety functions and different types of reaction to different situations (energize 144 to trip, de-energize to trip, immediate reaction, delayed reaction, …).
So overly simplistically IEC-60079-42 (TC31 WG42) is providing guidance on how to design “safety functions” (e.g., high high temperature interlock) to reduce the likelihood of ignition associated with say a motor following functional safety principles for Gas, Dust, and Mining applications.
The leadership team for IEC-60079-42 (TC31 WG42) is noted below.
TC31 Chair: martin.thedens@ptb.de
TC31 Secretary: Tom.Stack@bsigroup.com
Convenor: otto.walch@r-stahl.com
They can reach out to me or Rahul Bhojani or contact the leadership team for IEC-60079-42 directly to inquire about support.
Mike Scott