Class 2 Div 2 Area with Enclosed Room

[bearman]

Our facility is classified as Class 2 Div 2, however we have a small (12x8) room inside the facility that is used for milling of pastilles into a powder. The pastilles enter through piping, and leave via piping - thus under normal conditions, no material is visible in the room.

I'm planning on adding some instrumentation to this room, and am unsure whether I am limited by the Class 2 Div 2 regulations.

Is it possible to have an overall Class 2 Div 2 rating in a building with a room inside this area not being confined to this rating?

 

[petersonra]

Our facility is classified as Class 2 Div 2, however we have a small (12x8) room inside the facility that is used for milling of pastilles into a powder. The pastilles enter through piping, and leave via piping - thus under normal conditions, no material is visible in the room.

I'm planning on adding some instrumentation to this room, and am unsure whether I am limited by the Class 2 Div 2 regulations.

Is it possible to have an overall Class 2 Div 2 rating in a building with a room inside this area not being confined to this rating?

The answer is yes. Positive ventilation could indeed reduce the classification in such a room from C2D2 to non-classified. I do not believe that a non-ventilated room entirely surrounded by a classified area could be non-classifed. Mr. Alexander might be willing to give you his thoughts and he knows a lot more about this than I.

There should be some documentation that shows what the classification is for that room.

 

[bearman]

Thank you.

I had assumed that it would end up being Class 2, Div 2 - but I wanted to be sure before selecting instrumentation components.

I have one other question: If something is rated as a Class 1, Div 2, I would assume that it is automatically suitable for a Class 2, Div 2 as well, correct? Since Class 1, Div 2 is somewhat "more hazardous" than Class 2, Div 2 I would think this is correct - but since I'm here with the experts, I feel I should take the extra few minutes to get confirmation.

Thanks!

 

[petersonra]

I have one other question: If something is rated as a Class 1, Div 2, I would assume that it is automatically suitable for a Class 2, Div 2 as well, correct? Since Class 1, Div 2 is somewhat "more hazardous" than Class 2, Div 2 I would think this is correct - but since I'm here with the experts, I feel I should take the extra few minutes to get confirmation.

Thanks!

I would not assume that at all.

Now that I think about it, I can't recall ever having done anything in an area classified C2D2, and I don't recall ever seeing anything that says it is listed for use in a C1D2 area state anything at all about a C2D2 area.

 

[don_resqcapt19]

Often equipment suitable for Class I locations is not suitable for Class II locations. The issue is the maximum permitted surface temperature. It is lower for Class II than for Class I. That has to do with the problem of dust build up on the equipment in a Class II location. The equipment temperature has to remain lower than the ignition point of the product.
Don

 

[petersonra]

Often equipment suitable for Class I locations is not suitable for Class II locations. The issue is the maximum permitted surface temperature. It is lower for Class II than for Class I. That has to do with the problem of dust build up on the equipment in a Class II location. The equipment temperature has to remain lower than the ignition point of the product.
Don

I am not real up on Class II areas, but IIRC, in a C2D2 area, I seem to recall you can use general purpose equipment as long as it is in a dust tight box. Am I losing it or is that close to the truth?

 

[rbalex]

Bob and Don have both given good answers. I would just add a small comment.

Most Class II locations are grossly over Classified, I would carefully review NFPA 499.

The OP description would lead me to believe the closed piping alone would be sufficient to avoid classifying the room.