Retrofitting to Non-Incendive an area designed as IS.

[ControlDude2000]

We have a large installed base of IS devices, some but not all may have both a IS and NI approval. We also have a large installed IS infrastucture.

I am looking for information relating to using field devices with only an IS approval in NI circuits.

I have not found much information one way or the other.

Does anyone know of good resources?

Thanks

 

[rbalex]

Since intrinsically safe (IS) installations are recognized in all Class I, II and III locations, regardless of Division, [504.1] they are inherently acceptable where a nonincendive installation is acceptable in Articles 501(Class I), 502(Class II), 503(Class III) and 505 (Class I). They are also universally recognized in Article 506 for Zones 20, 21 and 22 through Sections 506.9(B)(1) and 506.9(C)(2)(2). Therefore an IS system or component does not need specific NI identification.

 

[ControlDude2000]

Since intrinsically safe (IS) installations are recognized in all Class I, II and III locations, regardless of Division, [504.1] they are inherently acceptable where a nonincendive installation is acceptable in Articles 501(Class I), 502(Class II), 503(Class III) and 505 (Class I). They are also universally recognized in Article 506 for Zones 20, 21 and 22 through Sections 506.9(B)(1) and 506.9(C)(2)(2). Therefore an IS system or component does not need specific NI identification.

Thanks.

Let me clarify what I mean by retrofitting.

The current plant is wired IS with either IS rated I/O or IS barriers protecting the usual simple devices or IS approved field devices.

The direction we are going is to upgrade the control system with new I/O which will be non-incendive. Hence IS devices will end up connected to non-incendive I/O.

My basis question is: Can a device FM approved as IS but with no NI approval be used in a NI circuit?

There is also the issue of reidentifying the IS infrastucture when it will no longer be IS.

 

[rbalex]

...
My basis question is: Can a device FM approved as IS but with no NI approval be used in a NI circuit?
...

Possibly not, but I believe the odds are still in your favor. I'd contact FM directly about questionable IS devices.

The "questionable IS devices" certainly wouldn't contribute additional system ignition energy, but I guess they could possibly fail since some IS apparatus depends on being connected to limited power sources in the first place. NI power sources are generally assumed to be limited too, but at a potentially higher level. This is why they are restricted to Division 2 applications. The question is whether failure of IS apparatus would go undetected and permit sufficient ignition energy for a prolonged period of time. I think it's doubtful, but conceivably possible.