Intrinsically Safe Systems RIO

[GuyMiller]

Hello All,

I need some clarification.. Are Intrinsically Safe Circuit Barriers required when the equipment is enclosed in a NEMA 7 Explosion Proof Enclosure and the proper conduit fitting, tubes, seals, drains,
breathers, etc are implemented? 
 

Guy

937-at001_-en-p.pdf

[DanW]

I have used instrumentation that has had an internal I/S component, like a radar level unit with an I/S connection to the radar antenna, where the unit was rated EX and that was required by the agency(s) doing the approvals.

I suppose you could put an IS barrier in the safe area for connection to the I/O points in the EX enclosure to prevent a fault in the safe area from providing an ignition source in the EX panel, but to my knowledge it is not required and I don't recall panels I've been in doing such.  People use I/S to avoid the EX enclosure, conduit, fittings, seals, etc.

[Tom Light]

they are not one in the same. intrinsically safe-incapable of starting ignition as a source, explosion proof-in the event of failure, the ignition/combustion will be contained within the box. you are probably well aware of that, but others reading may not. if the area of installation is considered intrinsically safe, an explosion proof alone containment does not meet requirements.